Convert watch page to flask framework

136 files changed, 52024 insertions, 431 deletions

diff --git a/python/click/__init__.py b/python/click/__init__.py
new file mode 100644
index 0000000..d3c3366
--- /dev/null
+++ b/python/click/__init__.py
@@ -0,0 +1,97 @@
+# -*- coding: utf-8 -*-
+"""
+click
+~~~~~
+
+Click is a simple Python module inspired by the stdlib optparse to make
+writing command line scripts fun. Unlike other modules, it's based
+around a simple API that does not come with too much magic and is
+composable.
+
+:copyright: © 2014 by the Pallets team.
+:license: BSD, see LICENSE.rst for more details.
+"""
+
+# Core classes
+from .core import Context, BaseCommand, Command, MultiCommand, Group, \
+     CommandCollection, Parameter, Option, Argument
+
+# Globals
+from .globals import get_current_context
+
+# Decorators
+from .decorators import pass_context, pass_obj, make_pass_decorator, \
+     command, group, argument, option, confirmation_option, \
+     password_option, version_option, help_option
+
+# Types
+from .types import ParamType, File, Path, Choice, IntRange, Tuple, \
+     DateTime, STRING, INT, FLOAT, BOOL, UUID, UNPROCESSED, FloatRange
+
+# Utilities
+from .utils import echo, get_binary_stream, get_text_stream, open_file, \
+     format_filename, get_app_dir, get_os_args
+
+# Terminal functions
+from .termui import prompt, confirm, get_terminal_size, echo_via_pager, \
+     progressbar, clear, style, unstyle, secho, edit, launch, getchar, \
+     pause
+
+# Exceptions
+from .exceptions import ClickException, UsageError, BadParameter, \
+     FileError, Abort, NoSuchOption, BadOptionUsage, BadArgumentUsage, \
+     MissingParameter
+
+# Formatting
+from .formatting import HelpFormatter, wrap_text
+
+# Parsing
+from .parser import OptionParser
+
+
+__all__ = [
+    # Core classes
+    'Context', 'BaseCommand', 'Command', 'MultiCommand', 'Group',
+    'CommandCollection', 'Parameter', 'Option', 'Argument',
+
+    # Globals
+    'get_current_context',
+
+    # Decorators
+    'pass_context', 'pass_obj', 'make_pass_decorator', 'command', 'group',
+    'argument', 'option', 'confirmation_option', 'password_option',
+    'version_option', 'help_option',
+
+    # Types
+    'ParamType', 'File', 'Path', 'Choice', 'IntRange', 'Tuple',
+    'DateTime', 'STRING', 'INT', 'FLOAT', 'BOOL', 'UUID', 'UNPROCESSED',
+    'FloatRange',
+
+    # Utilities
+    'echo', 'get_binary_stream', 'get_text_stream', 'open_file',
+    'format_filename', 'get_app_dir', 'get_os_args',
+
+    # Terminal functions
+    'prompt', 'confirm', 'get_terminal_size', 'echo_via_pager',
+    'progressbar', 'clear', 'style', 'unstyle', 'secho', 'edit', 'launch',
+    'getchar', 'pause',
+
+    # Exceptions
+    'ClickException', 'UsageError', 'BadParameter', 'FileError',
+    'Abort', 'NoSuchOption', 'BadOptionUsage', 'BadArgumentUsage',
+    'MissingParameter',
+
+    # Formatting
+    'HelpFormatter', 'wrap_text',
+
+    # Parsing
+    'OptionParser',
+]
+
+
+# Controls if click should emit the warning about the use of unicode
+# literals.
+disable_unicode_literals_warning = False
+
+
+__version__ = '7.0'
diff --git a/python/click/_bashcomplete.py b/python/click/_bashcomplete.py
new file mode 100644
index 0000000..a5f1084
--- /dev/null
+++ b/python/click/_bashcomplete.py
@@ -0,0 +1,293 @@
+import copy
+import os
+import re
+
+from .utils import echo
+from .parser import split_arg_string
+from .core import MultiCommand, Option, Argument
+from .types import Choice
+
+try:
+    from collections import abc
+except ImportError:
+    import collections as abc
+
+WORDBREAK = '='
+
+# Note, only BASH version 4.4 and later have the nosort option.
+COMPLETION_SCRIPT_BASH = '''
+%(complete_func)s() {
+    local IFS=$'\n'
+    COMPREPLY=( $( env COMP_WORDS="${COMP_WORDS[*]}" \\
+                   COMP_CWORD=$COMP_CWORD \\
+                   %(autocomplete_var)s=complete $1 ) )
+    return 0
+}
+
+%(complete_func)setup() {
+    local COMPLETION_OPTIONS=""
+    local BASH_VERSION_ARR=(${BASH_VERSION//./ })
+    # Only BASH version 4.4 and later have the nosort option.
+    if [ ${BASH_VERSION_ARR[0]} -gt 4 ] || ([ ${BASH_VERSION_ARR[0]} -eq 4 ] && [ ${BASH_VERSION_ARR[1]} -ge 4 ]); then
+        COMPLETION_OPTIONS="-o nosort"
+    fi
+
+    complete $COMPLETION_OPTIONS -F %(complete_func)s %(script_names)s
+}
+
+%(complete_func)setup
+'''
+
+COMPLETION_SCRIPT_ZSH = '''
+%(complete_func)s() {
+    local -a completions
+    local -a completions_with_descriptions
+    local -a response
+    response=("${(@f)$( env COMP_WORDS=\"${words[*]}\" \\
+                        COMP_CWORD=$((CURRENT-1)) \\
+                        %(autocomplete_var)s=\"complete_zsh\" \\
+                        %(script_names)s )}")
+
+    for key descr in ${(kv)response}; do
+      if [[ "$descr" == "_" ]]; then
+          completions+=("$key")
+      else
+          completions_with_descriptions+=("$key":"$descr")
+      fi
+    done
+
+    if [ -n "$completions_with_descriptions" ]; then
+        _describe -V unsorted completions_with_descriptions -U -Q
+    fi
+
+    if [ -n "$completions" ]; then
+        compadd -U -V unsorted -Q -a completions
+    fi
+    compstate[insert]="automenu"
+}
+
+compdef %(complete_func)s %(script_names)s
+'''
+
+_invalid_ident_char_re = re.compile(r'[^a-zA-Z0-9_]')
+
+
+def get_completion_script(prog_name, complete_var, shell):
+    cf_name = _invalid_ident_char_re.sub('', prog_name.replace('-', '_'))
+    script = COMPLETION_SCRIPT_ZSH if shell == 'zsh' else COMPLETION_SCRIPT_BASH
+    return (script % {
+        'complete_func': '_%s_completion' % cf_name,
+        'script_names': prog_name,
+        'autocomplete_var': complete_var,
+    }).strip() + ';'
+
+
+def resolve_ctx(cli, prog_name, args):
+    """
+    Parse into a hierarchy of contexts. Contexts are connected through the parent variable.
+    :param cli: command definition
+    :param prog_name: the program that is running
+    :param args: full list of args
+    :return: the final context/command parsed
+    """
+    ctx = cli.make_context(prog_name, args, resilient_parsing=True)
+    args = ctx.protected_args + ctx.args
+    while args:
+        if isinstance(ctx.command, MultiCommand):
+            if not ctx.command.chain:
+                cmd_name, cmd, args = ctx.command.resolve_command(ctx, args)
+                if cmd is None:
+                    return ctx
+                ctx = cmd.make_context(cmd_name, args, parent=ctx,
+                                       resilient_parsing=True)
+                args = ctx.protected_args + ctx.args
+            else:
+                # Walk chained subcommand contexts saving the last one.
+                while args:
+                    cmd_name, cmd, args = ctx.command.resolve_command(ctx, args)
+                    if cmd is None:
+                        return ctx
+                    sub_ctx = cmd.make_context(cmd_name, args, parent=ctx,
+                                               allow_extra_args=True,
+                                               allow_interspersed_args=False,
+                                               resilient_parsing=True)
+                    args = sub_ctx.args
+                ctx = sub_ctx
+                args = sub_ctx.protected_args + sub_ctx.args
+        else:
+            break
+    return ctx
+
+
+def start_of_option(param_str):
+    """
+    :param param_str: param_str to check
+    :return: whether or not this is the start of an option declaration (i.e. starts "-" or "--")
+    """
+    return param_str and param_str[:1] == '-'
+
+
+def is_incomplete_option(all_args, cmd_param):
+    """
+    :param all_args: the full original list of args supplied
+    :param cmd_param: the current command paramter
+    :return: whether or not the last option declaration (i.e. starts "-" or "--") is incomplete and
+    corresponds to this cmd_param. In other words whether this cmd_param option can still accept
+    values
+    """
+    if not isinstance(cmd_param, Option):
+        return False
+    if cmd_param.is_flag:
+        return False
+    last_option = None
+    for index, arg_str in enumerate(reversed([arg for arg in all_args if arg != WORDBREAK])):
+        if index + 1 > cmd_param.nargs:
+            break
+        if start_of_option(arg_str):
+            last_option = arg_str
+
+    return True if last_option and last_option in cmd_param.opts else False
+
+
+def is_incomplete_argument(current_params, cmd_param):
+    """
+    :param current_params: the current params and values for this argument as already entered
+    :param cmd_param: the current command parameter
+    :return: whether or not the last argument is incomplete and corresponds to this cmd_param. In
+    other words whether or not the this cmd_param argument can still accept values
+    """
+    if not isinstance(cmd_param, Argument):
+        return False
+    current_param_values = current_params[cmd_param.name]
+    if current_param_values is None:
+        return True
+    if cmd_param.nargs == -1:
+        return True
+    if isinstance(current_param_values, abc.Iterable) \
+            and cmd_param.nargs > 1 and len(current_param_values) < cmd_param.nargs:
+        return True
+    return False
+
+
+def get_user_autocompletions(ctx, args, incomplete, cmd_param):
+    """
+    :param ctx: context associated with the parsed command
+    :param args: full list of args
+    :param incomplete: the incomplete text to autocomplete
+    :param cmd_param: command definition
+    :return: all the possible user-specified completions for the param
+    """
+    results = []
+    if isinstance(cmd_param.type, Choice):
+        # Choices don't support descriptions.
+        results = [(c, None)
+                   for c in cmd_param.type.choices if str(c).startswith(incomplete)]
+    elif cmd_param.autocompletion is not None:
+        dynamic_completions = cmd_param.autocompletion(ctx=ctx,
+                                                       args=args,
+                                                       incomplete=incomplete)
+        results = [c if isinstance(c, tuple) else (c, None)
+                   for c in dynamic_completions]
+    return results
+
+
+def get_visible_commands_starting_with(ctx, starts_with):
+    """
+    :param ctx: context associated with the parsed command
+    :starts_with: string that visible commands must start with.
+    :return: all visible (not hidden) commands that start with starts_with.
+    """
+    for c in ctx.command.list_commands(ctx):
+        if c.startswith(starts_with):
+            command = ctx.command.get_command(ctx, c)
+            if not command.hidden:
+                yield command
+
+
+def add_subcommand_completions(ctx, incomplete, completions_out):
+    # Add subcommand completions.
+    if isinstance(ctx.command, MultiCommand):
+        completions_out.extend(
+            [(c.name, c.get_short_help_str()) for c in get_visible_commands_starting_with(ctx, incomplete)])
+
+    # Walk up the context list and add any other completion possibilities from chained commands
+    while ctx.parent is not None:
+        ctx = ctx.parent
+        if isinstance(ctx.command, MultiCommand) and ctx.command.chain:
+            remaining_commands = [c for c in get_visible_commands_starting_with(ctx, incomplete)
+                                  if c.name not in ctx.protected_args]
+            completions_out.extend([(c.name, c.get_short_help_str()) for c in remaining_commands])
+
+
+def get_choices(cli, prog_name, args, incomplete):
+    """
+    :param cli: command definition
+    :param prog_name: the program that is running
+    :param args: full list of args
+    :param incomplete: the incomplete text to autocomplete
+    :return: all the possible completions for the incomplete
+    """
+    all_args = copy.deepcopy(args)
+
+    ctx = resolve_ctx(cli, prog_name, args)
+    if ctx is None:
+        return []
+
+    # In newer versions of bash long opts with '='s are partitioned, but it's easier to parse
+    # without the '='
+    if start_of_option(incomplete) and WORDBREAK in incomplete:
+        partition_incomplete = incomplete.partition(WORDBREAK)
+        all_args.append(partition_incomplete[0])
+        incomplete = partition_incomplete[2]
+    elif incomplete == WORDBREAK:
+        incomplete = ''
+
+    completions = []
+    if start_of_option(incomplete):
+        # completions for partial options
+        for param in ctx.command.params:
+            if isinstance(param, Option) and not param.hidden:
+                param_opts = [param_opt for param_opt in param.opts +
+                              param.secondary_opts if param_opt not in all_args or param.multiple]
+                completions.extend([(o, param.help) for o in param_opts if o.startswith(incomplete)])
+        return completions
+    # completion for option values from user supplied values
+    for param in ctx.command.params:
+        if is_incomplete_option(all_args, param):
+            return get_user_autocompletions(ctx, all_args, incomplete, param)
+    # completion for argument values from user supplied values
+    for param in ctx.command.params:
+        if is_incomplete_argument(ctx.params, param):
+            return get_user_autocompletions(ctx, all_args, incomplete, param)
+
+    add_subcommand_completions(ctx, incomplete, completions)
+    # Sort before returning so that proper ordering can be enforced in custom types.
+    return sorted(completions)
+
+
+def do_complete(cli, prog_name, include_descriptions):
+    cwords = split_arg_string(os.environ['COMP_WORDS'])
+    cword = int(os.environ['COMP_CWORD'])
+    args = cwords[1:cword]
+    try:
+        incomplete = cwords[cword]
+    except IndexError:
+        incomplete = ''
+
+    for item in get_choices(cli, prog_name, args, incomplete):
+        echo(item[0])
+        if include_descriptions:
+            # ZSH has trouble dealing with empty array parameters when returned from commands, so use a well defined character '_' to indicate no description is present.
+            echo(item[1] if item[1] else '_')
+
+    return True
+
+
+def bashcomplete(cli, prog_name, complete_var, complete_instr):
+    if complete_instr.startswith('source'):
+        shell = 'zsh' if complete_instr == 'source_zsh' else 'bash'
+        echo(get_completion_script(prog_name, complete_var, shell))
+        return True
+    elif complete_instr == 'complete' or complete_instr == 'complete_zsh':
+        return do_complete(cli, prog_name, complete_instr == 'complete_zsh')
+    return False
diff --git a/python/click/_compat.py b/python/click/_compat.py
new file mode 100644
index 0000000..937e230
--- /dev/null
+++ b/python/click/_compat.py
@@ -0,0 +1,703 @@
+import re
+import io
+import os
+import sys
+import codecs
+from weakref import WeakKeyDictionary
+
+
+PY2 = sys.version_info[0] == 2
+CYGWIN = sys.platform.startswith('cygwin')
+# Determine local App Engine environment, per Google's own suggestion
+APP_ENGINE = ('APPENGINE_RUNTIME' in os.environ and
+              'Development/' in os.environ['SERVER_SOFTWARE'])
+WIN = sys.platform.startswith('win') and not APP_ENGINE
+DEFAULT_COLUMNS = 80
+
+
+_ansi_re = re.compile(r'\033\[((?:\d|;)*)([a-zA-Z])')
+
+
+def get_filesystem_encoding():
+    return sys.getfilesystemencoding() or sys.getdefaultencoding()
+
+
+def _make_text_stream(stream, encoding, errors,
+                      force_readable=False, force_writable=False):
+    if encoding is None:
+        encoding = get_best_encoding(stream)
+    if errors is None:
+        errors = 'replace'
+    return _NonClosingTextIOWrapper(stream, encoding, errors,
+                                    line_buffering=True,
+                                    force_readable=force_readable,
+                                    force_writable=force_writable)
+
+
+def is_ascii_encoding(encoding):
+    """Checks if a given encoding is ascii."""
+    try:
+        return codecs.lookup(encoding).name == 'ascii'
+    except LookupError:
+        return False
+
+
+def get_best_encoding(stream):
+    """Returns the default stream encoding if not found."""
+    rv = getattr(stream, 'encoding', None) or sys.getdefaultencoding()
+    if is_ascii_encoding(rv):
+        return 'utf-8'
+    return rv
+
+
+class _NonClosingTextIOWrapper(io.TextIOWrapper):
+
+    def __init__(self, stream, encoding, errors,
+                 force_readable=False, force_writable=False, **extra):
+        self._stream = stream = _FixupStream(stream, force_readable,
+                                             force_writable)
+        io.TextIOWrapper.__init__(self, stream, encoding, errors, **extra)
+
+    # The io module is a place where the Python 3 text behavior
+    # was forced upon Python 2, so we need to unbreak
+    # it to look like Python 2.
+    if PY2:
+        def write(self, x):
+            if isinstance(x, str) or is_bytes(x):
+                try:
+                    self.flush()
+                except Exception:
+                    pass
+                return self.buffer.write(str(x))
+            return io.TextIOWrapper.write(self, x)
+
+        def writelines(self, lines):
+            for line in lines:
+                self.write(line)
+
+    def __del__(self):
+        try:
+            self.detach()
+        except Exception:
+            pass
+
+    def isatty(self):
+        # https://bitbucket.org/pypy/pypy/issue/1803
+        return self._stream.isatty()
+
+
+class _FixupStream(object):
+    """The new io interface needs more from streams than streams
+    traditionally implement.  As such, this fix-up code is necessary in
+    some circumstances.
+
+    The forcing of readable and writable flags are there because some tools
+    put badly patched objects on sys (one such offender are certain version
+    of jupyter notebook).
+    """
+
+    def __init__(self, stream, force_readable=False, force_writable=False):
+        self._stream = stream
+        self._force_readable = force_readable
+        self._force_writable = force_writable
+
+    def __getattr__(self, name):
+        return getattr(self._stream, name)
+
+    def read1(self, size):
+        f = getattr(self._stream, 'read1', None)
+        if f is not None:
+            return f(size)
+        # We only dispatch to readline instead of read in Python 2 as we
+        # do not want cause problems with the different implementation
+        # of line buffering.
+        if PY2:
+            return self._stream.readline(size)
+        return self._stream.read(size)
+
+    def readable(self):
+        if self._force_readable:
+            return True
+        x = getattr(self._stream, 'readable', None)
+        if x is not None:
+            return x()
+        try:
+            self._stream.read(0)
+        except Exception:
+            return False
+        return True
+
+    def writable(self):
+        if self._force_writable:
+            return True
+        x = getattr(self._stream, 'writable', None)
+        if x is not None:
+            return x()
+        try:
+            self._stream.write('')
+        except Exception:
+            try:
+                self._stream.write(b'')
+            except Exception:
+                return False
+        return True
+
+    def seekable(self):
+        x = getattr(self._stream, 'seekable', None)
+        if x is not None:
+            return x()
+        try:
+            self._stream.seek(self._stream.tell())
+        except Exception:
+            return False
+        return True
+
+
+if PY2:
+    text_type = unicode
+    bytes = str
+    raw_input = raw_input
+    string_types = (str, unicode)
+    int_types = (int, long)
+    iteritems = lambda x: x.iteritems()
+    range_type = xrange
+
+    def is_bytes(x):
+        return isinstance(x, (buffer, bytearray))
+
+    _identifier_re = re.compile(r'^[a-zA-Z_][a-zA-Z0-9_]*$')
+
+    # For Windows, we need to force stdout/stdin/stderr to binary if it's
+    # fetched for that.  This obviously is not the most correct way to do
+    # it as it changes global state.  Unfortunately, there does not seem to
+    # be a clear better way to do it as just reopening the file in binary
+    # mode does not change anything.
+    #
+    # An option would be to do what Python 3 does and to open the file as
+    # binary only, patch it back to the system, and then use a wrapper
+    # stream that converts newlines.  It's not quite clear what's the
+    # correct option here.
+    #
+    # This code also lives in _winconsole for the fallback to the console
+    # emulation stream.
+    #
+    # There are also Windows environments where the `msvcrt` module is not
+    # available (which is why we use try-catch instead of the WIN variable
+    # here), such as the Google App Engine development server on Windows. In
+    # those cases there is just nothing we can do.
+    def set_binary_mode(f):
+        return f
+
+    try:
+        import msvcrt
+    except ImportError:
+        pass
+    else:
+        def set_binary_mode(f):
+            try:
+                fileno = f.fileno()
+            except Exception:
+                pass
+            else:
+                msvcrt.setmode(fileno, os.O_BINARY)
+            return f
+
+    try:
+        import fcntl
+    except ImportError:
+        pass
+    else:
+        def set_binary_mode(f):
+            try:
+                fileno = f.fileno()
+            except Exception:
+                pass
+            else:
+                flags = fcntl.fcntl(fileno, fcntl.F_GETFL)
+                fcntl.fcntl(fileno, fcntl.F_SETFL, flags & ~os.O_NONBLOCK)
+            return f
+
+    def isidentifier(x):
+        return _identifier_re.search(x) is not None
+
+    def get_binary_stdin():
+        return set_binary_mode(sys.stdin)
+
+    def get_binary_stdout():
+        _wrap_std_stream('stdout')
+        return set_binary_mode(sys.stdout)
+
+    def get_binary_stderr():
+        _wrap_std_stream('stderr')
+        return set_binary_mode(sys.stderr)
+
+    def get_text_stdin(encoding=None, errors=None):
+        rv = _get_windows_console_stream(sys.stdin, encoding, errors)
+        if rv is not None:
+            return rv
+        return _make_text_stream(sys.stdin, encoding, errors,
+                                 force_readable=True)
+
+    def get_text_stdout(encoding=None, errors=None):
+        _wrap_std_stream('stdout')
+        rv = _get_windows_console_stream(sys.stdout, encoding, errors)
+        if rv is not None:
+            return rv
+        return _make_text_stream(sys.stdout, encoding, errors,
+                                 force_writable=True)
+
+    def get_text_stderr(encoding=None, errors=None):
+        _wrap_std_stream('stderr')
+        rv = _get_windows_console_stream(sys.stderr, encoding, errors)
+        if rv is not None:
+            return rv
+        return _make_text_stream(sys.stderr, encoding, errors,
+                                 force_writable=True)
+
+    def filename_to_ui(value):
+        if isinstance(value, bytes):
+            value = value.decode(get_filesystem_encoding(), 'replace')
+        return value
+else:
+    import io
+    text_type = str
+    raw_input = input
+    string_types = (str,)
+    int_types = (int,)
+    range_type = range
+    isidentifier = lambda x: x.isidentifier()
+    iteritems = lambda x: iter(x.items())
+
+    def is_bytes(x):
+        return isinstance(x, (bytes, memoryview, bytearray))
+
+    def _is_binary_reader(stream, default=False):
+        try:
+            return isinstance(stream.read(0), bytes)
+        except Exception:
+            return default
+            # This happens in some cases where the stream was already
+            # closed.  In this case, we assume the default.
+
+    def _is_binary_writer(stream, default=False):
+        try:
+            stream.write(b'')
+        except Exception:
+            try:
+                stream.write('')
+                return False
+            except Exception:
+                pass
+            return default
+        return True
+
+    def _find_binary_reader(stream):
+        # We need to figure out if the given stream is already binary.
+        # This can happen because the official docs recommend detaching
+        # the streams to get binary streams.  Some code might do this, so
+        # we need to deal with this case explicitly.
+        if _is_binary_reader(stream, False):
+            return stream
+
+        buf = getattr(stream, 'buffer', None)
+
+        # Same situation here; this time we assume that the buffer is
+        # actually binary in case it's closed.
+        if buf is not None and _is_binary_reader(buf, True):
+            return buf
+
+    def _find_binary_writer(stream):
+        # We need to figure out if the given stream is already binary.
+        # This can happen because the official docs recommend detatching
+        # the streams to get binary streams.  Some code might do this, so
+        # we need to deal with this case explicitly.
+        if _is_binary_writer(stream, False):
+            return stream
+
+        buf = getattr(stream, 'buffer', None)
+
+        # Same situation here; this time we assume that the buffer is
+        # actually binary in case it's closed.
+        if buf is not None and _is_binary_writer(buf, True):
+            return buf
+
+    def _stream_is_misconfigured(stream):
+        """A stream is misconfigured if its encoding is ASCII."""
+        # If the stream does not have an encoding set, we assume it's set
+        # to ASCII.  This appears to happen in certain unittest
+        # environments.  It's not quite clear what the correct behavior is
+        # but this at least will force Click to recover somehow.
+        return is_ascii_encoding(getattr(stream, 'encoding', None) or 'ascii')
+
+    def _is_compatible_text_stream(stream, encoding, errors):
+        stream_encoding = getattr(stream, 'encoding', None)
+        stream_errors = getattr(stream, 'errors', None)
+
+        # Perfect match.
+        if stream_encoding == encoding and stream_errors == errors:
+            return True
+
+        # Otherwise, it's only a compatible stream if we did not ask for
+        # an encoding.
+        if encoding is None:
+            return stream_encoding is not None
+
+        return False
+
+    def _force_correct_text_reader(text_reader, encoding, errors,
+                                   force_readable=False):
+        if _is_binary_reader(text_reader, False):
+            binary_reader = text_reader
+        else:
+            # If there is no target encoding set, we need to verify that the
+            # reader is not actually misconfigured.
+            if encoding is None and not _stream_is_misconfigured(text_reader):
+                return text_reader
+
+            if _is_compatible_text_stream(text_reader, encoding, errors):
+                return text_reader
+
+            # If the reader has no encoding, we try to find the underlying
+            # binary reader for it.  If that fails because the environment is
+            # misconfigured, we silently go with the same reader because this
+            # is too common to happen.  In that case, mojibake is better than
+            # exceptions.
+            binary_reader = _find_binary_reader(text_reader)
+            if binary_reader is None:
+                return text_reader
+
+        # At this point, we default the errors to replace instead of strict
+        # because nobody handles those errors anyways and at this point
+        # we're so fundamentally fucked that nothing can repair it.
+        if errors is None:
+            errors = 'replace'
+        return _make_text_stream(binary_reader, encoding, errors,
+                                 force_readable=force_readable)
+
+    def _force_correct_text_writer(text_writer, encoding, errors,
+                                   force_writable=False):
+        if _is_binary_writer(text_writer, False):
+            binary_writer = text_writer
+        else:
+            # If there is no target encoding set, we need to verify that the
+            # writer is not actually misconfigured.
+            if encoding is None and not _stream_is_misconfigured(text_writer):
+                return text_writer
+
+            if _is_compatible_text_stream(text_writer, encoding, errors):
+                return text_writer
+
+            # If the writer has no encoding, we try to find the underlying
+            # binary writer for it.  If that fails because the environment is
+            # misconfigured, we silently go with the same writer because this
+            # is too common to happen.  In that case, mojibake is better than
+            # exceptions.
+            binary_writer = _find_binary_writer(text_writer)
+            if binary_writer is None:
+                return text_writer
+
+        # At this point, we default the errors to replace instead of strict
+        # because nobody handles those errors anyways and at this point
+        # we're so fundamentally fucked that nothing can repair it.
+        if errors is None:
+            errors = 'replace'
+        return _make_text_stream(binary_writer, encoding, errors,
+                                 force_writable=force_writable)
+
+    def get_binary_stdin():
+        reader = _find_binary_reader(sys.stdin)
+        if reader is None:
+            raise RuntimeError('Was not able to determine binary '
+                               'stream for sys.stdin.')
+        return reader
+
+    def get_binary_stdout():
+        writer = _find_binary_writer(sys.stdout)
+        if writer is None:
+            raise RuntimeError('Was not able to determine binary '
+                               'stream for sys.stdout.')
+        return writer
+
+    def get_binary_stderr():
+        writer = _find_binary_writer(sys.stderr)
+        if writer is None:
+            raise RuntimeError('Was not able to determine binary '
+                               'stream for sys.stderr.')
+        return writer
+
+    def get_text_stdin(encoding=None, errors=None):
+        rv = _get_windows_console_stream(sys.stdin, encoding, errors)
+        if rv is not None:
+            return rv
+        return _force_correct_text_reader(sys.stdin, encoding, errors,
+                                          force_readable=True)
+
+    def get_text_stdout(encoding=None, errors=None):
+        rv = _get_windows_console_stream(sys.stdout, encoding, errors)
+        if rv is not None:
+            return rv
+        return _force_correct_text_writer(sys.stdout, encoding, errors,
+                                          force_writable=True)
+
+    def get_text_stderr(encoding=None, errors=None):
+        rv = _get_windows_console_stream(sys.stderr, encoding, errors)
+        if rv is not None:
+            return rv
+        return _force_correct_text_writer(sys.stderr, encoding, errors,
+                                          force_writable=True)
+
+    def filename_to_ui(value):
+        if isinstance(value, bytes):
+            value = value.decode(get_filesystem_encoding(), 'replace')
+        else:
+            value = value.encode('utf-8', 'surrogateescape') \
+                .decode('utf-8', 'replace')
+        return value
+
+
+def get_streerror(e, default=None):
+    if hasattr(e, 'strerror'):
+        msg = e.strerror
+    else:
+        if default is not None:
+            msg = default
+        else:
+            msg = str(e)
+    if isinstance(msg, bytes):
+        msg = msg.decode('utf-8', 'replace')
+    return msg
+
+
+def open_stream(filename, mode='r', encoding=None, errors='strict',
+                atomic=False):
+    # Standard streams first.  These are simple because they don't need
+    # special handling for the atomic flag.  It's entirely ignored.
+    if filename == '-':
+        if any(m in mode for m in ['w', 'a', 'x']):
+            if 'b' in mode:
+                return get_binary_stdout(), False
+            return get_text_stdout(encoding=encoding, errors=errors), False
+        if 'b' in mode:
+            return get_binary_stdin(), False
+        return get_text_stdin(encoding=encoding, errors=errors), False
+
+    # Non-atomic writes directly go out through the regular open functions.
+    if not atomic:
+        if encoding is None:
+            return open(filename, mode), True
+        return io.open(filename, mode, encoding=encoding, errors=errors), True
+
+    # Some usability stuff for atomic writes
+    if 'a' in mode:
+        raise ValueError(
+            'Appending to an existing file is not supported, because that '
+            'would involve an expensive `copy`-operation to a temporary '
+            'file. Open the file in normal `w`-mode and copy explicitly '
+            'if that\'s what you\'re after.'
+        )
+    if 'x' in mode:
+        raise ValueError('Use the `overwrite`-parameter instead.')
+    if 'w' not in mode:
+        raise ValueError('Atomic writes only make sense with `w`-mode.')
+
+    # Atomic writes are more complicated.  They work by opening a file
+    # as a proxy in the same folder and then using the fdopen
+    # functionality to wrap it in a Python file.  Then we wrap it in an
+    # atomic file that moves the file over on close.
+    import tempfile
+    fd, tmp_filename = tempfile.mkstemp(dir=os.path.dirname(filename),
+                                        prefix='.__atomic-write')
+
+    if encoding is not None:
+        f = io.open(fd, mode, encoding=encoding, errors=errors)
+    else:
+        f = os.fdopen(fd, mode)
+
+    return _AtomicFile(f, tmp_filename, os.path.realpath(filename)), True
+
+
+# Used in a destructor call, needs extra protection from interpreter cleanup.
+if hasattr(os, 'replace'):
+    _replace = os.replace
+    _can_replace = True
+else:
+    _replace = os.rename
+    _can_replace = not WIN
+
+
+class _AtomicFile(object):
+
+    def __init__(self, f, tmp_filename, real_filename):
+        self._f = f
+        self._tmp_filename = tmp_filename
+        self._real_filename = real_filename
+        self.closed = False
+
+    @property
+    def name(self):
+        return self._real_filename
+
+    def close(self, delete=False):
+        if self.closed:
+            return
+        self._f.close()
+        if not _can_replace:
+            try:
+                os.remove(self._real_filename)
+            except OSError:
+                pass
+        _replace(self._tmp_filename, self._real_filename)
+        self.closed = True
+
+    def __getattr__(self, name):
+        return getattr(self._f, name)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.close(delete=exc_type is not None)
+
+    def __repr__(self):
+        return repr(self._f)
+
+
+auto_wrap_for_ansi = None
+colorama = None
+get_winterm_size = None
+
+
+def strip_ansi(value):
+    return _ansi_re.sub('', value)
+
+
+def should_strip_ansi(stream=None, color=None):
+    if color is None:
+        if stream is None:
+            stream = sys.stdin
+        return not isatty(stream)
+    return not color
+
+
+# If we're on Windows, we provide transparent integration through
+# colorama.  This will make ANSI colors through the echo function
+# work automatically.
+if WIN:
+    # Windows has a smaller terminal
+    DEFAULT_COLUMNS = 79
+
+    from ._winconsole import _get_windows_console_stream, _wrap_std_stream
+
+    def _get_argv_encoding():
+        import locale
+        return locale.getpreferredencoding()
+
+    if PY2:
+        def raw_input(prompt=''):
+            sys.stderr.flush()
+            if prompt:
+                stdout = _default_text_stdout()
+                stdout.write(prompt)
+            stdin = _default_text_stdin()
+            return stdin.readline().rstrip('\r\n')
+
+    try:
+        import colorama
+    except ImportError:
+        pass
+    else:
+        _ansi_stream_wrappers = WeakKeyDictionary()
+
+        def auto_wrap_for_ansi(stream, color=None):
+            """This function wraps a stream so that calls through colorama
+            are issued to the win32 console API to recolor on demand.  It
+            also ensures to reset the colors if a write call is interrupted
+            to not destroy the console afterwards.
+            """
+            try:
+                cached = _ansi_stream_wrappers.get(stream)
+            except Exception:
+                cached = None
+            if cached is not None:
+                return cached
+            strip = should_strip_ansi(stream, color)
+            ansi_wrapper = colorama.AnsiToWin32(stream, strip=strip)
+            rv = ansi_wrapper.stream
+            _write = rv.write
+
+            def _safe_write(s):
+                try:
+                    return _write(s)
+                except:
+                    ansi_wrapper.reset_all()
+                    raise
+
+            rv.write = _safe_write
+            try:
+                _ansi_stream_wrappers[stream] = rv
+            except Exception:
+                pass
+            return rv
+
+        def get_winterm_size():
+            win = colorama.win32.GetConsoleScreenBufferInfo(
+                colorama.win32.STDOUT).srWindow
+            return win.Right - win.Left, win.Bottom - win.Top
+else:
+    def _get_argv_encoding():
+        return getattr(sys.stdin, 'encoding', None) or get_filesystem_encoding()
+
+    _get_windows_console_stream = lambda *x: None
+    _wrap_std_stream = lambda *x: None
+
+
+def term_len(x):
+    return len(strip_ansi(x))
+
+
+def isatty(stream):
+    try:
+        return stream.isatty()
+    except Exception:
+        return False
+
+
+def _make_cached_stream_func(src_func, wrapper_func):
+    cache = WeakKeyDictionary()
+    def func():
+        stream = src_func()
+        try:
+            rv = cache.get(stream)
+        except Exception:
+            rv = None
+        if rv is not None:
+            return rv
+        rv = wrapper_func()
+        try:
+            stream = src_func()  # In case wrapper_func() modified the stream
+            cache[stream] = rv
+        except Exception:
+            pass
+        return rv
+    return func
+
+
+_default_text_stdin = _make_cached_stream_func(
+    lambda: sys.stdin, get_text_stdin)
+_default_text_stdout = _make_cached_stream_func(
+    lambda: sys.stdout, get_text_stdout)
+_default_text_stderr = _make_cached_stream_func(
+    lambda: sys.stderr, get_text_stderr)
+
+
+binary_streams = {
+    'stdin': get_binary_stdin,
+    'stdout': get_binary_stdout,
+    'stderr': get_binary_stderr,
+}
+
+text_streams = {
+    'stdin': get_text_stdin,
+    'stdout': get_text_stdout,
+    'stderr': get_text_stderr,
+}
diff --git a/python/click/_termui_impl.py b/python/click/_termui_impl.py
new file mode 100644
index 0000000..00a8e5e
--- /dev/null
+++ b/python/click/_termui_impl.py
@@ -0,0 +1,621 @@
+# -*- coding: utf-8 -*-
+"""
+click._termui_impl
+~~~~~~~~~~~~~~~~~~
+
+This module contains implementations for the termui module. To keep the
+import time of Click down, some infrequently used functionality is
+placed in this module and only imported as needed.
+
+:copyright: © 2014 by the Pallets team.
+:license: BSD, see LICENSE.rst for more details.
+"""
+
+import os
+import sys
+import time
+import math
+import contextlib
+from ._compat import _default_text_stdout, range_type, PY2, isatty, \
+     open_stream, strip_ansi, term_len, get_best_encoding, WIN, int_types, \
+     CYGWIN
+from .utils import echo
+from .exceptions import ClickException
+
+
+if os.name == 'nt':
+    BEFORE_BAR = '\r'
+    AFTER_BAR = '\n'
+else:
+    BEFORE_BAR = '\r\033[?25l'
+    AFTER_BAR = '\033[?25h\n'
+
+
+def _length_hint(obj):
+    """Returns the length hint of an object."""
+    try:
+        return len(obj)
+    except (AttributeError, TypeError):
+        try:
+            get_hint = type(obj).__length_hint__
+        except AttributeError:
+            return None
+        try:
+            hint = get_hint(obj)
+        except TypeError:
+            return None
+        if hint is NotImplemented or \
+           not isinstance(hint, int_types) or \
+           hint < 0:
+            return None
+        return hint
+
+
+class ProgressBar(object):
+
+    def __init__(self, iterable, length=None, fill_char='#', empty_char=' ',
+                 bar_template='%(bar)s', info_sep='  ', show_eta=True,
+                 show_percent=None, show_pos=False, item_show_func=None,
+                 label=None, file=None, color=None, width=30):
+        self.fill_char = fill_char
+        self.empty_char = empty_char
+        self.bar_template = bar_template
+        self.info_sep = info_sep
+        self.show_eta = show_eta
+        self.show_percent = show_percent
+        self.show_pos = show_pos
+        self.item_show_func = item_show_func
+        self.label = label or ''
+        if file is None:
+            file = _default_text_stdout()
+        self.file = file
+        self.color = color
+        self.width = width
+        self.autowidth = width == 0
+
+        if length is None:
+            length = _length_hint(iterable)
+        if iterable is None:
+            if length is None:
+                raise TypeError('iterable or length is required')
+            iterable = range_type(length)
+        self.iter = iter(iterable)
+        self.length = length
+        self.length_known = length is not None
+        self.pos = 0
+        self.avg = []
+        self.start = self.last_eta = time.time()
+        self.eta_known = False
+        self.finished = False
+        self.max_width = None
+        self.entered = False
+        self.current_item = None
+        self.is_hidden = not isatty(self.file)
+        self._last_line = None
+        self.short_limit = 0.5
+
+    def __enter__(self):
+        self.entered = True
+        self.render_progress()
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.render_finish()
+
+    def __iter__(self):
+        if not self.entered:
+            raise RuntimeError('You need to use progress bars in a with block.')
+        self.render_progress()
+        return self.generator()
+
+    def is_fast(self):
+        return time.time() - self.start <= self.short_limit
+
+    def render_finish(self):
+        if self.is_hidden or self.is_fast():
+            return
+        self.file.write(AFTER_BAR)
+        self.file.flush()
+
+    @property
+    def pct(self):
+        if self.finished:
+            return 1.0
+        return min(self.pos / (float(self.length) or 1), 1.0)
+
+    @property
+    def time_per_iteration(self):
+        if not self.avg:
+            return 0.0
+        return sum(self.avg) / float(len(self.avg))
+
+    @property
+    def eta(self):
+        if self.length_known and not self.finished:
+            return self.time_per_iteration * (self.length - self.pos)
+        return 0.0
+
+    def format_eta(self):
+        if self.eta_known:
+            t = int(self.eta)
+            seconds = t % 60
+            t //= 60
+            minutes = t % 60
+            t //= 60
+            hours = t % 24
+            t //= 24
+            if t > 0:
+                days = t
+                return '%dd %02d:%02d:%02d' % (days, hours, minutes, seconds)
+            else:
+                return '%02d:%02d:%02d' % (hours, minutes, seconds)
+        return ''
+
+    def format_pos(self):
+        pos = str(self.pos)
+        if self.length_known:
+            pos += '/%s' % self.length
+        return pos
+
+    def format_pct(self):
+        return ('% 4d%%' % int(self.pct * 100))[1:]
+
+    def format_bar(self):
+        if self.length_known:
+            bar_length = int(self.pct * self.width)
+            bar = self.fill_char * bar_length
+            bar += self.empty_char * (self.width - bar_length)
+        elif self.finished:
+            bar = self.fill_char * self.width
+        else:
+            bar = list(self.empty_char * (self.width or 1))
+            if self.time_per_iteration != 0:
+                bar[int((math.cos(self.pos * self.time_per_iteration)
+                    / 2.0 + 0.5) * self.width)] = self.fill_char
+            bar = ''.join(bar)
+        return bar
+
+    def format_progress_line(self):
+        show_percent = self.show_percent
+
+        info_bits = []
+        if self.length_known and show_percent is None:
+            show_percent = not self.show_pos
+
+        if self.show_pos:
+            info_bits.append(self.format_pos())
+        if show_percent:
+            info_bits.append(self.format_pct())
+        if self.show_eta and self.eta_known and not self.finished:
+            info_bits.append(self.format_eta())
+        if self.item_show_func is not None:
+            item_info = self.item_show_func(self.current_item)
+            if item_info is not None:
+                info_bits.append(item_info)
+
+        return (self.bar_template % {
+            'label': self.label,
+            'bar': self.format_bar(),
+            'info': self.info_sep.join(info_bits)
+        }).rstrip()
+
+    def render_progress(self):
+        from .termui import get_terminal_size
+
+        if self.is_hidden:
+            return
+
+        buf = []
+        # Update width in case the terminal has been resized
+        if self.autowidth:
+            old_width = self.width
+            self.width = 0
+            clutter_length = term_len(self.format_progress_line())
+            new_width = max(0, get_terminal_size()[0] - clutter_length)
+            if new_width < old_width:
+                buf.append(BEFORE_BAR)
+                buf.append(' ' * self.max_width)
+                self.max_width = new_width
+            self.width = new_width
+
+        clear_width = self.width
+        if self.max_width is not None:
+            clear_width = self.max_width
+
+        buf.append(BEFORE_BAR)
+        line = self.format_progress_line()
+        line_len = term_len(line)
+        if self.max_width is None or self.max_width < line_len:
+            self.max_width = line_len
+
+        buf.append(line)
+        buf.append(' ' * (clear_width - line_len))
+        line = ''.join(buf)
+        # Render the line only if it changed.
+
+        if line != self._last_line and not self.is_fast():
+            self._last_line = line
+            echo(line, file=self.file, color=self.color, nl=False)
+            self.file.flush()
+
+    def make_step(self, n_steps):
+        self.pos += n_steps
+        if self.length_known and self.pos >= self.length:
+            self.finished = True
+
+        if (time.time() - self.last_eta) < 1.0:
+            return
+
+        self.last_eta = time.time()
+
+        # self.avg is a rolling list of length <= 7 of steps where steps are
+        # defined as time elapsed divided by the total progress through
+        # self.length.
+        if self.pos:
+            step = (time.time() - self.start) / self.pos
+        else:
+            step = time.time() - self.start
+
+        self.avg = self.avg[-6:] + [step]
+
+        self.eta_known = self.length_known
+
+    def update(self, n_steps):
+        self.make_step(n_steps)
+        self.render_progress()
+
+    def finish(self):
+        self.eta_known = 0
+        self.current_item = None
+        self.finished = True
+
+    def generator(self):
+        """
+        Returns a generator which yields the items added to the bar during
+        construction, and updates the progress bar *after* the yielded block
+        returns.
+        """
+        if not self.entered:
+            raise RuntimeError('You need to use progress bars in a with block.')
+
+        if self.is_hidden:
+            for rv in self.iter:
+                yield rv
+        else:
+            for rv in self.iter:
+                self.current_item = rv
+                yield rv
+                self.update(1)
+            self.finish()
+            self.render_progress()
+
+
+def pager(generator, color=None):
+    """Decide what method to use for paging through text."""
+    stdout = _default_text_stdout()
+    if not isatty(sys.stdin) or not isatty(stdout):
+        return _nullpager(stdout, generator, color)
+    pager_cmd = (os.environ.get('PAGER', None) or '').strip()
+    if pager_cmd:
+        if WIN:
+            return _tempfilepager(generator, pager_cmd, color)
+        return _pipepager(generator, pager_cmd, color)
+    if os.environ.get('TERM') in ('dumb', 'emacs'):
+        return _nullpager(stdout, generator, color)
+    if WIN or sys.platform.startswith('os2'):
+        return _tempfilepager(generator, 'more <', color)
+    if hasattr(os, 'system') and os.system('(less) 2>/dev/null') == 0:
+        return _pipepager(generator, 'less', color)
+
+    import tempfile
+    fd, filename = tempfile.mkstemp()
+    os.close(fd)
+    try:
+        if hasattr(os, 'system') and os.system('more "%s"' % filename) == 0:
+            return _pipepager(generator, 'more', color)
+        return _nullpager(stdout, generator, color)
+    finally:
+        os.unlink(filename)
+
+
+def _pipepager(generator, cmd, color):
+    """Page through text by feeding it to another program.  Invoking a
+    pager through this might support colors.
+    """
+    import subprocess
+    env = dict(os.environ)
+
+    # If we're piping to less we might support colors under the
+    # condition that
+    cmd_detail = cmd.rsplit('/', 1)[-1].split()
+    if color is None and cmd_detail[0] == 'less':
+        less_flags = os.environ.get('LESS', '') + ' '.join(cmd_detail[1:])
+        if not less_flags:
+            env['LESS'] = '-R'
+            color = True
+        elif 'r' in less_flags or 'R' in less_flags:
+            color = True
+
+    c = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE,
+                         env=env)
+    encoding = get_best_encoding(c.stdin)
+    try:
+        for text in generator:
+            if not color:
+                text = strip_ansi(text)
+
+            c.stdin.write(text.encode(encoding, 'replace'))
+    except (IOError, KeyboardInterrupt):
+        pass
+    else:
+        c.stdin.close()
+
+    # Less doesn't respect ^C, but catches it for its own UI purposes (aborting
+    # search or other commands inside less).
+    #
+    # That means when the user hits ^C, the parent process (click) terminates,
+    # but less is still alive, paging the output and messing up the terminal.
+    #
+    # If the user wants to make the pager exit on ^C, they should set
+    # `LESS='-K'`. It's not our decision to make.
+    while True:
+        try:
+            c.wait()
+        except KeyboardInterrupt:
+            pass
+        else:
+            break
+
+
+def _tempfilepager(generator, cmd, color):
+    """Page through text by invoking a program on a temporary file."""
+    import tempfile
+    filename = tempfile.mktemp()
+    # TODO: This never terminates if the passed generator never terminates.
+    text = "".join(generator)
+    if not color:
+        text = strip_ansi(text)
+    encoding = get_best_encoding(sys.stdout)
+    with open_stream(filename, 'wb')[0] as f:
+        f.write(text.encode(encoding))
+    try:
+        os.system(cmd + ' "' + filename + '"')
+    finally:
+        os.unlink(filename)
+
+
+def _nullpager(stream, generator, color):
+    """Simply print unformatted text.  This is the ultimate fallback."""
+    for text in generator:
+        if not color:
+            text = strip_ansi(text)
+        stream.write(text)
+
+
+class Editor(object):
+
+    def __init__(self, editor=None, env=None, require_save=True,
+                 extension='.txt'):
+        self.editor = editor
+        self.env = env
+        self.require_save = require_save
+        self.extension = extension
+
+    def get_editor(self):
+        if self.editor is not None:
+            return self.editor
+        for key in 'VISUAL', 'EDITOR':
+            rv = os.environ.get(key)
+            if rv:
+                return rv
+        if WIN:
+            return 'notepad'
+        for editor in 'vim', 'nano':
+            if os.system('which %s >/dev/null 2>&1' % editor) == 0:
+                return editor
+        return 'vi'
+
+    def edit_file(self, filename):
+        import subprocess
+        editor = self.get_editor()
+        if self.env:
+            environ = os.environ.copy()
+            environ.update(self.env)
+        else:
+            environ = None
+        try:
+            c = subprocess.Popen('%s "%s"' % (editor, filename),
+                                 env=environ, shell=True)
+            exit_code = c.wait()
+            if exit_code != 0:
+                raise ClickException('%s: Editing failed!' % editor)
+        except OSError as e:
+            raise ClickException('%s: Editing failed: %s' % (editor, e))
+
+    def edit(self, text):
+        import tempfile
+
+        text = text or ''
+        if text and not text.endswith('\n'):
+            text += '\n'
+
+        fd, name = tempfile.mkstemp(prefix='editor-', suffix=self.extension)
+        try:
+            if WIN:
+                encoding = 'utf-8-sig'
+                text = text.replace('\n', '\r\n')
+            else:
+                encoding = 'utf-8'
+            text = text.encode(encoding)
+
+            f = os.fdopen(fd, 'wb')
+            f.write(text)
+            f.close()
+            timestamp = os.path.getmtime(name)
+
+            self.edit_file(name)
+
+            if self.require_save \
+               and os.path.getmtime(name) == timestamp:
+                return None
+
+            f = open(name, 'rb')
+            try:
+                rv = f.read()
+            finally:
+                f.close()
+            return rv.decode('utf-8-sig').replace('\r\n', '\n')
+        finally:
+            os.unlink(name)
+
+
+def open_url(url, wait=False, locate=False):
+    import subprocess
+
+    def _unquote_file(url):
+        try:
+            import urllib
+        except ImportError:
+            import urllib
+        if url.startswith('file://'):
+            url = urllib.unquote(url[7:])
+        return url
+
+    if sys.platform == 'darwin':
+        args = ['open']
+        if wait:
+            args.append('-W')
+        if locate:
+            args.append('-R')
+        args.append(_unquote_file(url))
+        null = open('/dev/null', 'w')
+        try:
+            return subprocess.Popen(args, stderr=null).wait()
+        finally:
+            null.close()
+    elif WIN:
+        if locate:
+            url = _unquote_file(url)
+            args = 'explorer /select,"%s"' % _unquote_file(
+                url.replace('"', ''))
+        else:
+            args = 'start %s "" "%s"' % (
+                wait and '/WAIT' or '', url.replace('"', ''))
+        return os.system(args)
+    elif CYGWIN:
+        if locate:
+            url = _unquote_file(url)
+            args = 'cygstart "%s"' % (os.path.dirname(url).replace('"', ''))
+        else:
+            args = 'cygstart %s "%s"' % (
+                wait and '-w' or '', url.replace('"', ''))
+        return os.system(args)
+
+    try:
+        if locate:
+            url = os.path.dirname(_unquote_file(url)) or '.'
+        else:
+            url = _unquote_file(url)
+        c = subprocess.Popen(['xdg-open', url])
+        if wait:
+            return c.wait()
+        return 0
+    except OSError:
+        if url.startswith(('http://', 'https://')) and not locate and not wait:
+            import webbrowser
+            webbrowser.open(url)
+            return 0
+        return 1
+
+
+def _translate_ch_to_exc(ch):
+    if ch == u'\x03':
+        raise KeyboardInterrupt()
+    if ch == u'\x04' and not WIN:  # Unix-like, Ctrl+D
+        raise EOFError()
+    if ch == u'\x1a' and WIN:      # Windows, Ctrl+Z
+        raise EOFError()
+
+
+if WIN:
+    import msvcrt
+
+    @contextlib.contextmanager
+    def raw_terminal():
+        yield
+
+    def getchar(echo):
+        # The function `getch` will return a bytes object corresponding to
+        # the pressed character. Since Windows 10 build 1803, it will also
+        # return \x00 when called a second time after pressing a regular key.
+        #
+        # `getwch` does not share this probably-bugged behavior. Moreover, it
+        # returns a Unicode object by default, which is what we want.
+        #
+        # Either of these functions will return \x00 or \xe0 to indicate
+        # a special key, and you need to call the same function again to get
+        # the "rest" of the code. The fun part is that \u00e0 is
+        # "latin small letter a with grave", so if you type that on a French
+        # keyboard, you _also_ get a \xe0.
+        # E.g., consider the Up arrow. This returns \xe0 and then \x48. The
+        # resulting Unicode string reads as "a with grave" + "capital H".
+        # This is indistinguishable from when the user actually types
+        # "a with grave" and then "capital H".
+        #
+        # When \xe0 is returned, we assume it's part of a special-key sequence
+        # and call `getwch` again, but that means that when the user types
+        # the \u00e0 character, `getchar` doesn't return until a second
+        # character is typed.
+        # The alternative is returning immediately, but that would mess up
+        # cross-platform handling of arrow keys and others that start with
+        # \xe0. Another option is using `getch`, but then we can't reliably
+        # read non-ASCII characters, because return values of `getch` are
+        # limited to the current 8-bit codepage.
+        #
+        # Anyway, Click doesn't claim to do this Right(tm), and using `getwch`
+        # is doing the right thing in more situations than with `getch`.
+        if echo:
+            func = msvcrt.getwche
+        else:
+            func = msvcrt.getwch
+
+        rv = func()
+        if rv in (u'\x00', u'\xe0'):
+            # \x00 and \xe0 are control characters that indicate special key,
+            # see above.
+            rv += func()
+        _translate_ch_to_exc(rv)
+        return rv
+else:
+    import tty
+    import termios
+
+    @contextlib.contextmanager
+    def raw_terminal():
+        if not isatty(sys.stdin):
+            f = open('/dev/tty')
+            fd = f.fileno()
+        else:
+            fd = sys.stdin.fileno()
+            f = None
+        try:
+            old_settings = termios.tcgetattr(fd)
+            try:
+                tty.setraw(fd)
+                yield fd
+            finally:
+                termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
+                sys.stdout.flush()
+                if f is not None:
+                    f.close()
+        except termios.error:
+            pass
+
+    def getchar(echo):
+        with raw_terminal() as fd:
+            ch = os.read(fd, 32)
+            ch = ch.decode(get_best_encoding(sys.stdin), 'replace')
+            if echo and isatty(sys.stdout):
+                sys.stdout.write(ch)
+            _translate_ch_to_exc(ch)
+            return ch
diff --git a/python/click/_textwrap.py b/python/click/_textwrap.py
new file mode 100644
index 0000000..7e77603
--- /dev/null
+++ b/python/click/_textwrap.py
@@ -0,0 +1,38 @@
+import textwrap
+from contextlib import contextmanager
+
+
+class TextWrapper(textwrap.TextWrapper):
+
+    def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
+        space_left = max(width - cur_len, 1)
+
+        if self.break_long_words:
+            last = reversed_chunks[-1]
+            cut = last[:space_left]
+            res = last[space_left:]
+            cur_line.append(cut)
+            reversed_chunks[-1] = res
+        elif not cur_line:
+            cur_line.append(reversed_chunks.pop())
+
+    @contextmanager
+    def extra_indent(self, indent):
+        old_initial_indent = self.initial_indent
+        old_subsequent_indent = self.subsequent_indent
+        self.initial_indent += indent
+        self.subsequent_indent += indent
+        try:
+            yield
+        finally:
+            self.initial_indent = old_initial_indent
+            self.subsequent_indent = old_subsequent_indent
+
+    def indent_only(self, text):
+        rv = []
+        for idx, line in enumerate(text.splitlines()):
+            indent = self.initial_indent
+            if idx > 0:
+                indent = self.subsequent_indent
+            rv.append(indent + line)
+        return '\n'.join(rv)
diff --git a/python/click/_unicodefun.py b/python/click/_unicodefun.py
new file mode 100644
index 0000000..620edff
--- /dev/null
+++ b/python/click/_unicodefun.py
@@ -0,0 +1,125 @@
+import os
+import sys
+import codecs
+
+from ._compat import PY2
+
+
+# If someone wants to vendor click, we want to ensure the
+# correct package is discovered.  Ideally we could use a
+# relative import here but unfortunately Python does not
+# support that.
+click = sys.modules[__name__.rsplit('.', 1)[0]]
+
+
+def _find_unicode_literals_frame():
+    import __future__
+    if not hasattr(sys, '_getframe'):  # not all Python implementations have it
+        return 0
+    frm = sys._getframe(1)
+    idx = 1
+    while frm is not None:
+        if frm.f_globals.get('__name__', '').startswith('click.'):
+            frm = frm.f_back
+            idx += 1
+        elif frm.f_code.co_flags & __future__.unicode_literals.compiler_flag:
+            return idx
+        else:
+            break
+    return 0
+
+
+def _check_for_unicode_literals():
+    if not __debug__:
+        return
+    if not PY2 or click.disable_unicode_literals_warning:
+        return
+    bad_frame = _find_unicode_literals_frame()
+    if bad_frame <= 0:
+        return
+    from warnings import warn
+    warn(Warning('Click detected the use of the unicode_literals '
+                 '__future__ import.  This is heavily discouraged '
+                 'because it can introduce subtle bugs in your '
+                 'code.  You should instead use explicit u"" literals '
+                 'for your unicode strings.  For more information see '
+                 'https://click.palletsprojects.com/python3/'),
+         stacklevel=bad_frame)
+
+
+def _verify_python3_env():
+    """Ensures that the environment is good for unicode on Python 3."""
+    if PY2:
+        return
+    try:
+        import locale
+        fs_enc = codecs.lookup(locale.getpreferredencoding()).name
+    except Exception:
+        fs_enc = 'ascii'
+    if fs_enc != 'ascii':
+        return
+
+    extra = ''
+    if os.name == 'posix':
+        import subprocess
+        try:
+            rv = subprocess.Popen(['locale', '-a'], stdout=subprocess.PIPE,
+                                  stderr=subprocess.PIPE).communicate()[0]
+        except OSError:
+            rv = b''
+        good_locales = set()
+        has_c_utf8 = False
+
+        # Make sure we're operating on text here.
+        if isinstance(rv, bytes):
+            rv = rv.decode('ascii', 'replace')
+
+        for line in rv.splitlines():
+            locale = line.strip()
+            if locale.lower().endswith(('.utf-8', '.utf8')):
+                good_locales.add(locale)
+                if locale.lower() in ('c.utf8', 'c.utf-8'):
+                    has_c_utf8 = True
+
+        extra += '\n\n'
+        if not good_locales:
+            extra += (
+                'Additional information: on this system no suitable UTF-8\n'
+                'locales were discovered.  This most likely requires resolving\n'
+                'by reconfiguring the locale system.'
+            )
+        elif has_c_utf8:
+            extra += (
+                'This system supports the C.UTF-8 locale which is recommended.\n'
+                'You might be able to resolve your issue by exporting the\n'
+                'following environment variables:\n\n'
+                '    export LC_ALL=C.UTF-8\n'
+                '    export LANG=C.UTF-8'
+            )
+        else:
+            extra += (
+                'This system lists a couple of UTF-8 supporting locales that\n'
+                'you can pick from.  The following suitable locales were\n'
+                'discovered: %s'
+            ) % ', '.join(sorted(good_locales))
+
+        bad_locale = None
+        for locale in os.environ.get('LC_ALL'), os.environ.get('LANG'):
+            if locale and locale.lower().endswith(('.utf-8', '.utf8')):
+                bad_locale = locale
+            if locale is not None:
+                break
+        if bad_locale is not None:
+            extra += (
+                '\n\nClick discovered that you exported a UTF-8 locale\n'
+                'but the locale system could not pick up from it because\n'
+                'it does not exist.  The exported locale is "%s" but it\n'
+                'is not supported'
+            ) % bad_locale
+
+    raise RuntimeError(
+        'Click will abort further execution because Python 3 was'
+        ' configured to use ASCII as encoding for the environment.'
+        ' Consult https://click.palletsprojects.com/en/7.x/python3/ for'
+        ' mitigation steps.' + extra
+    )
diff --git a/python/click/_winconsole.py b/python/click/_winconsole.py
new file mode 100644
index 0000000..bbb080d
--- /dev/null
+++ b/python/click/_winconsole.py
@@ -0,0 +1,307 @@
+# -*- coding: utf-8 -*-
+# This module is based on the excellent work by Adam Bartoš who
+# provided a lot of what went into the implementation here in
+# the discussion to issue1602 in the Python bug tracker.
+#
+# There are some general differences in regards to how this works
+# compared to the original patches as we do not need to patch
+# the entire interpreter but just work in our little world of
+# echo and prmopt.
+
+import io
+import os
+import sys
+import zlib
+import time
+import ctypes
+import msvcrt
+from ._compat import _NonClosingTextIOWrapper, text_type, PY2
+from ctypes import byref, POINTER, c_int, c_char, c_char_p, \
+     c_void_p, py_object, c_ssize_t, c_ulong, windll, WINFUNCTYPE
+try:
+    from ctypes import pythonapi
+    PyObject_GetBuffer = pythonapi.PyObject_GetBuffer
+    PyBuffer_Release = pythonapi.PyBuffer_Release
+except ImportError:
+    pythonapi = None
+from ctypes.wintypes import LPWSTR, LPCWSTR
+
+
+c_ssize_p = POINTER(c_ssize_t)
+
+kernel32 = windll.kernel32
+GetStdHandle = kernel32.GetStdHandle
+ReadConsoleW = kernel32.ReadConsoleW
+WriteConsoleW = kernel32.WriteConsoleW
+GetLastError = kernel32.GetLastError
+GetCommandLineW = WINFUNCTYPE(LPWSTR)(
+    ('GetCommandLineW', windll.kernel32))
+CommandLineToArgvW = WINFUNCTYPE(
+    POINTER(LPWSTR), LPCWSTR, POINTER(c_int))(
+        ('CommandLineToArgvW', windll.shell32))
+
+
+STDIN_HANDLE = GetStdHandle(-10)
+STDOUT_HANDLE = GetStdHandle(-11)
+STDERR_HANDLE = GetStdHandle(-12)
+
+
+PyBUF_SIMPLE = 0
+PyBUF_WRITABLE = 1
+
+ERROR_SUCCESS = 0
+ERROR_NOT_ENOUGH_MEMORY = 8
+ERROR_OPERATION_ABORTED = 995
+
+STDIN_FILENO = 0
+STDOUT_FILENO = 1
+STDERR_FILENO = 2
+
+EOF = b'\x1a'
+MAX_BYTES_WRITTEN = 32767
+
+
+class Py_buffer(ctypes.Structure):
+    _fields_ = [
+        ('buf', c_void_p),
+        ('obj', py_object),
+        ('len', c_ssize_t),
+        ('itemsize', c_ssize_t),
+        ('readonly', c_int),
+        ('ndim', c_int),
+        ('format', c_char_p),
+        ('shape', c_ssize_p),
+        ('strides', c_ssize_p),
+        ('suboffsets', c_ssize_p),
+        ('internal', c_void_p)
+    ]
+
+    if PY2:
+        _fields_.insert(-1, ('smalltable', c_ssize_t * 2))
+
+
+# On PyPy we cannot get buffers so our ability to operate here is
+# serverly limited.
+if pythonapi is None:
+    get_buffer = None
+else:
+    def get_buffer(obj, writable=False):
+        buf = Py_buffer()
+        flags = PyBUF_WRITABLE if writable else PyBUF_SIMPLE
+        PyObject_GetBuffer(py_object(obj), byref(buf), flags)
+        try:
+            buffer_type = c_char * buf.len
+            return buffer_type.from_address(buf.buf)
+        finally:
+            PyBuffer_Release(byref(buf))
+
+
+class _WindowsConsoleRawIOBase(io.RawIOBase):
+
+    def __init__(self, handle):
+        self.handle = handle
+
+    def isatty(self):
+        io.RawIOBase.isatty(self)
+        return True
+
+
+class _WindowsConsoleReader(_WindowsConsoleRawIOBase):
+
+    def readable(self):
+        return True
+
+    def readinto(self, b):
+        bytes_to_be_read = len(b)
+        if not bytes_to_be_read:
+            return 0
+        elif bytes_to_be_read % 2:
+            raise ValueError('cannot read odd number of bytes from '
+                             'UTF-16-LE encoded console')
+
+        buffer = get_buffer(b, writable=True)
+        code_units_to_be_read = bytes_to_be_read // 2
+        code_units_read = c_ulong()
+
+        rv = ReadConsoleW(self.handle, buffer, code_units_to_be_read,
+                          byref(code_units_read), None)
+        if GetLastError() == ERROR_OPERATION_ABORTED:
+            # wait for KeyboardInterrupt
+            time.sleep(0.1)
+        if not rv:
+            raise OSError('Windows error: %s' % GetLastError())
+
+        if buffer[0] == EOF:
+            return 0
+        return 2 * code_units_read.value
+
+
+class _WindowsConsoleWriter(_WindowsConsoleRawIOBase):
+
+    def writable(self):
+        return True
+
+    @staticmethod
+    def _get_error_message(errno):
+        if errno == ERROR_SUCCESS:
+            return 'ERROR_SUCCESS'
+        elif errno == ERROR_NOT_ENOUGH_MEMORY:
+            return 'ERROR_NOT_ENOUGH_MEMORY'
+        return 'Windows error %s' % errno
+
+    def write(self, b):
+        bytes_to_be_written = len(b)
+        buf = get_buffer(b)
+        code_units_to_be_written = min(bytes_to_be_written,
+                                       MAX_BYTES_WRITTEN) // 2
+        code_units_written = c_ulong()
+
+        WriteConsoleW(self.handle, buf, code_units_to_be_written,
+                      byref(code_units_written), None)
+        bytes_written = 2 * code_units_written.value
+
+        if bytes_written == 0 and bytes_to_be_written > 0:
+            raise OSError(self._get_error_message(GetLastError()))
+        return bytes_written
+
+
+class ConsoleStream(object):
+
+    def __init__(self, text_stream, byte_stream):
+        self._text_stream = text_stream
+        self.buffer = byte_stream
+
+    @property
+    def name(self):
+        return self.buffer.name
+
+    def write(self, x):
+        if isinstance(x, text_type):
+            return self._text_stream.write(x)
+        try:
+            self.flush()
+        except Exception:
+            pass
+        return self.buffer.write(x)
+
+    def writelines(self, lines):
+        for line in lines:
+            self.write(line)
+
+    def __getattr__(self, name):
+        return getattr(self._text_stream, name)
+
+    def isatty(self):
+        return self.buffer.isatty()
+
+    def __repr__(self):
+        return '<ConsoleStream name=%r encoding=%r>' % (
+            self.name,
+            self.encoding,
+        )
+
+
+class WindowsChunkedWriter(object):
+    """
+    Wraps a stream (such as stdout), acting as a transparent proxy for all
+    attribute access apart from method 'write()' which we wrap to write in
+    limited chunks due to a Windows limitation on binary console streams.
+    """
+    def __init__(self, wrapped):
+        # double-underscore everything to prevent clashes with names of
+        # attributes on the wrapped stream object.
+        self.__wrapped = wrapped
+
+    def __getattr__(self, name):
+        return getattr(self.__wrapped, name)
+
+    def write(self, text):
+        total_to_write = len(text)
+        written = 0
+
+        while written < total_to_write:
+            to_write = min(total_to_write - written, MAX_BYTES_WRITTEN)
+            self.__wrapped.write(text[written:written+to_write])
+            written += to_write
+
+
+_wrapped_std_streams = set()
+
+
+def _wrap_std_stream(name):
+    # Python 2 & Windows 7 and below
+    if PY2 and sys.getwindowsversion()[:2] <= (6, 1) and name not in _wrapped_std_streams:
+        setattr(sys, name, WindowsChunkedWriter(getattr(sys, name)))
+        _wrapped_std_streams.add(name)
+
+
+def _get_text_stdin(buffer_stream):
+    text_stream = _NonClosingTextIOWrapper(
+        io.BufferedReader(_WindowsConsoleReader(STDIN_HANDLE)),
+        'utf-16-le', 'strict', line_buffering=True)
+    return ConsoleStream(text_stream, buffer_stream)
+
+
+def _get_text_stdout(buffer_stream):
+    text_stream = _NonClosingTextIOWrapper(
+        io.BufferedWriter(_WindowsConsoleWriter(STDOUT_HANDLE)),
+        'utf-16-le', 'strict', line_buffering=True)
+    return ConsoleStream(text_stream, buffer_stream)
+
+
+def _get_text_stderr(buffer_stream):
+    text_stream = _NonClosingTextIOWrapper(
+        io.BufferedWriter(_WindowsConsoleWriter(STDERR_HANDLE)),
+        'utf-16-le', 'strict', line_buffering=True)
+    return ConsoleStream(text_stream, buffer_stream)
+
+
+if PY2:
+    def _hash_py_argv():
+        return zlib.crc32('\x00'.join(sys.argv[1:]))
+
+    _initial_argv_hash = _hash_py_argv()
+
+    def _get_windows_argv():
+        argc = c_int(0)
+        argv_unicode = CommandLineToArgvW(GetCommandLineW(), byref(argc))
+        argv = [argv_unicode[i] for i in range(0, argc.value)]
+
+        if not hasattr(sys, 'frozen'):
+            argv = argv[1:]
+            while len(argv) > 0:
+                arg = argv[0]
+                if not arg.startswith('-') or arg == '-':
+                    break
+                argv = argv[1:]
+                if arg.startswith(('-c', '-m')):
+                    break
+
+        return argv[1:]
+
+
+_stream_factories = {
+    0: _get_text_stdin,
+    1: _get_text_stdout,
+    2: _get_text_stderr,
+}
+
+
+def _get_windows_console_stream(f, encoding, errors):
+    if get_buffer is not None and \
+       encoding in ('utf-16-le', None) \
+       and errors in ('strict', None) and \
+       hasattr(f, 'isatty') and f.isatty():
+        func = _stream_factories.get(f.fileno())
+        if func is not None:
+            if not PY2:
+                f = getattr(f, 'buffer', None)
+                if f is None:
+                    return None
+            else:
+                # If we are on Python 2 we need to set the stream that we
+                # deal with to binary mode as otherwise the exercise if a
+                # bit moot.  The same problems apply as for
+                # get_binary_stdin and friends from _compat.
+                msvcrt.setmode(f.fileno(), os.O_BINARY)
+            return func(f)
diff --git a/python/click/core.py b/python/click/core.py
new file mode 100644
index 0000000..7a1e342
--- /dev/null
+++ b/python/click/core.py
@@ -0,0 +1,1856 @@
+import errno
+import inspect
+import os
+import sys
+from contextlib import contextmanager
+from itertools import repeat
+from functools import update_wrapper
+
+from .types import convert_type, IntRange, BOOL
+from .utils import PacifyFlushWrapper, make_str, make_default_short_help, \
+     echo, get_os_args
+from .exceptions import ClickException, UsageError, BadParameter, Abort, \
+     MissingParameter, Exit
+from .termui import prompt, confirm, style
+from .formatting import HelpFormatter, join_options
+from .parser import OptionParser, split_opt
+from .globals import push_context, pop_context
+
+from ._compat import PY2, isidentifier, iteritems, string_types
+from ._unicodefun import _check_for_unicode_literals, _verify_python3_env
+
+
+_missing = object()
+
+
+SUBCOMMAND_METAVAR = 'COMMAND [ARGS]...'
+SUBCOMMANDS_METAVAR = 'COMMAND1 [ARGS]... [COMMAND2 [ARGS]...]...'
+
+DEPRECATED_HELP_NOTICE = ' (DEPRECATED)'
+DEPRECATED_INVOKE_NOTICE = 'DeprecationWarning: ' + \
+                           'The command %(name)s is deprecated.'
+
+
+def _maybe_show_deprecated_notice(cmd):
+    if cmd.deprecated:
+        echo(style(DEPRECATED_INVOKE_NOTICE % {'name': cmd.name}, fg='red'), err=True)
+
+
+def fast_exit(code):
+    """Exit without garbage collection, this speeds up exit by about 10ms for
+    things like bash completion.
+    """
+    sys.stdout.flush()
+    sys.stderr.flush()
+    os._exit(code)
+
+
+def _bashcomplete(cmd, prog_name, complete_var=None):
+    """Internal handler for the bash completion support."""
+    if complete_var is None:
+        complete_var = '_%s_COMPLETE' % (prog_name.replace('-', '_')).upper()
+    complete_instr = os.environ.get(complete_var)
+    if not complete_instr:
+        return
+
+    from ._bashcomplete import bashcomplete
+    if bashcomplete(cmd, prog_name, complete_var, complete_instr):
+        fast_exit(1)
+
+
+def _check_multicommand(base_command, cmd_name, cmd, register=False):
+    if not base_command.chain or not isinstance(cmd, MultiCommand):
+        return
+    if register:
+        hint = 'It is not possible to add multi commands as children to ' \
+               'another multi command that is in chain mode'
+    else:
+        hint = 'Found a multi command as subcommand to a multi command ' \
+               'that is in chain mode.  This is not supported'
+    raise RuntimeError('%s.  Command "%s" is set to chain and "%s" was '
+                       'added as subcommand but it in itself is a '
+                       'multi command.  ("%s" is a %s within a chained '
+                       '%s named "%s").' % (
+                           hint, base_command.name, cmd_name,
+                           cmd_name, cmd.__class__.__name__,
+                           base_command.__class__.__name__,
+                           base_command.name))
+
+
+def batch(iterable, batch_size):
+    return list(zip(*repeat(iter(iterable), batch_size)))
+
+
+def invoke_param_callback(callback, ctx, param, value):
+    code = getattr(callback, '__code__', None)
+    args = getattr(code, 'co_argcount', 3)
+
+    if args < 3:
+        # This will become a warning in Click 3.0:
+        from warnings import warn
+        warn(Warning('Invoked legacy parameter callback "%s".  The new '
+                     'signature for such callbacks starting with '
+                     'click 2.0 is (ctx, param, value).'
+                     % callback), stacklevel=3)
+        return callback(ctx, value)
+    return callback(ctx, param, value)
+
+
+@contextmanager
+def augment_usage_errors(ctx, param=None):
+    """Context manager that attaches extra information to exceptions that
+    fly.
+    """
+    try:
+        yield
+    except BadParameter as e:
+        if e.ctx is None:
+            e.ctx = ctx
+        if param is not None and e.param is None:
+            e.param = param
+        raise
+    except UsageError as e:
+        if e.ctx is None:
+            e.ctx = ctx
+        raise
+
+
+def iter_params_for_processing(invocation_order, declaration_order):
+    """Given a sequence of parameters in the order as should be considered
+    for processing and an iterable of parameters that exist, this returns
+    a list in the correct order as they should be processed.
+    """
+    def sort_key(item):
+        try:
+            idx = invocation_order.index(item)
+        except ValueError:
+            idx = float('inf')
+        return (not item.is_eager, idx)
+
+    return sorted(declaration_order, key=sort_key)
+
+
+class Context(object):
+    """The context is a special internal object that holds state relevant
+    for the script execution at every single level.  It's normally invisible
+    to commands unless they opt-in to getting access to it.
+
+    The context is useful as it can pass internal objects around and can
+    control special execution features such as reading data from
+    environment variables.
+
+    A context can be used as context manager in which case it will call
+    :meth:`close` on teardown.
+
+    .. versionadded:: 2.0
+       Added the `resilient_parsing`, `help_option_names`,
+       `token_normalize_func` parameters.
+
+    .. versionadded:: 3.0
+       Added the `allow_extra_args` and `allow_interspersed_args`
+       parameters.
+
+    .. versionadded:: 4.0
+       Added the `color`, `ignore_unknown_options`, and
+       `max_content_width` parameters.
+
+    :param command: the command class for this context.
+    :param parent: the parent context.
+    :param info_name: the info name for this invocation.  Generally this
+                      is the most descriptive name for the script or
+                      command.  For the toplevel script it is usually
+                      the name of the script, for commands below it it's
+                      the name of the script.
+    :param obj: an arbitrary object of user data.
+    :param auto_envvar_prefix: the prefix to use for automatic environment
+                               variables.  If this is `None` then reading
+                               from environment variables is disabled.  This
+                               does not affect manually set environment
+                               variables which are always read.
+    :param default_map: a dictionary (like object) with default values
+                        for parameters.
+    :param terminal_width: the width of the terminal.  The default is
+                           inherit from parent context.  If no context
+                           defines the terminal width then auto
+                           detection will be applied.
+    :param max_content_width: the maximum width for content rendered by
+                              Click (this currently only affects help
+                              pages).  This defaults to 80 characters if
+                              not overridden.  In other words: even if the
+                              terminal is larger than that, Click will not
+                              format things wider than 80 characters by
+                              default.  In addition to that, formatters might
+                              add some safety mapping on the right.
+    :param resilient_parsing: if this flag is enabled then Click will
+                              parse without any interactivity or callback
+                              invocation.  Default values will also be
+                              ignored.  This is useful for implementing
+                              things such as completion support.
+    :param allow_extra_args: if this is set to `True` then extra arguments
+                             at the end will not raise an error and will be
+                             kept on the context.  The default is to inherit
+                             from the command.
+    :param allow_interspersed_args: if this is set to `False` then options
+                                    and arguments cannot be mixed.  The
+                                    default is to inherit from the command.
+    :param ignore_unknown_options: instructs click to ignore options it does
+                                   not know and keeps them for later
+                                   processing.
+    :param help_option_names: optionally a list of strings that define how
+                              the default help parameter is named.  The
+                              default is ``['--help']``.
+    :param token_normalize_func: an optional function that is used to
+                                 normalize tokens (options, choices,
+                                 etc.).  This for instance can be used to
+                                 implement case insensitive behavior.
+    :param color: controls if the terminal supports ANSI colors or not.  The
+                  default is autodetection.  This is only needed if ANSI
+                  codes are used in texts that Click prints which is by
+                  default not the case.  This for instance would affect
+                  help output.
+    """
+
+    def __init__(self, command, parent=None, info_name=None, obj=None,
+                 auto_envvar_prefix=None, default_map=None,
+                 terminal_width=None, max_content_width=None,
+                 resilient_parsing=False, allow_extra_args=None,
+                 allow_interspersed_args=None,
+                 ignore_unknown_options=None, help_option_names=None,
+                 token_normalize_func=None, color=None):
+        #: the parent context or `None` if none exists.
+        self.parent = parent
+        #: the :class:`Command` for this context.
+        self.command = command
+        #: the descriptive information name
+        self.info_name = info_name
+        #: the parsed parameters except if the value is hidden in which
+        #: case it's not remembered.
+        self.params = {}
+        #: the leftover arguments.
+        self.args = []
+        #: protected arguments.  These are arguments that are prepended
+        #: to `args` when certain parsing scenarios are encountered but
+        #: must be never propagated to another arguments.  This is used
+        #: to implement nested parsing.
+        self.protected_args = []
+        if obj is None and parent is not None:
+            obj = parent.obj
+        #: the user object stored.
+        self.obj = obj
+        self._meta = getattr(parent, 'meta', {})
+
+        #: A dictionary (-like object) with defaults for parameters.
+        if default_map is None \
+           and parent is not None \
+           and parent.default_map is not None:
+            default_map = parent.default_map.get(info_name)
+        self.default_map = default_map
+
+        #: This flag indicates if a subcommand is going to be executed. A
+        #: group callback can use this information to figure out if it's
+        #: being executed directly or because the execution flow passes
+        #: onwards to a subcommand. By default it's None, but it can be
+        #: the name of the subcommand to execute.
+        #:
+        #: If chaining is enabled this will be set to ``'*'`` in case
+        #: any commands are executed.  It is however not possible to
+        #: figure out which ones.  If you require this knowledge you
+        #: should use a :func:`resultcallback`.
+        self.invoked_subcommand = None
+
+        if terminal_width is None and parent is not None:
+            terminal_width = parent.terminal_width
+        #: The width of the terminal (None is autodetection).
+        self.terminal_width = terminal_width
+
+        if max_content_width is None and parent is not None:
+            max_content_width = parent.max_content_width
+        #: The maximum width of formatted content (None implies a sensible
+        #: default which is 80 for most things).
+        self.max_content_width = max_content_width
+
+        if allow_extra_args is None:
+            allow_extra_args = command.allow_extra_args
+        #: Indicates if the context allows extra args or if it should
+        #: fail on parsing.
+        #:
+        #: .. versionadded:: 3.0
+        self.allow_extra_args = allow_extra_args
+
+        if allow_interspersed_args is None:
+            allow_interspersed_args = command.allow_interspersed_args
+        #: Indicates if the context allows mixing of arguments and
+        #: options or not.
+        #:
+        #: .. versionadded:: 3.0
+        self.allow_interspersed_args = allow_interspersed_args
+
+        if ignore_unknown_options is None:
+            ignore_unknown_options = command.ignore_unknown_options
+        #: Instructs click to ignore options that a command does not
+        #: understand and will store it on the context for later
+        #: processing.  This is primarily useful for situations where you
+        #: want to call into external programs.  Generally this pattern is
+        #: strongly discouraged because it's not possibly to losslessly
+        #: forward all arguments.
+        #:
+        #: .. versionadded:: 4.0
+        self.ignore_unknown_options = ignore_unknown_options
+
+        if help_option_names is None:
+            if parent is not None:
+                help_option_names = parent.help_option_names
+            else:
+                help_option_names = ['--help']
+
+        #: The names for the help options.
+        self.help_option_names = help_option_names
+
+        if token_normalize_func is None and parent is not None:
+            token_normalize_func = parent.token_normalize_func
+
+        #: An optional normalization function for tokens.  This is
+        #: options, choices, commands etc.
+        self.token_normalize_func = token_normalize_func
+
+        #: Indicates if resilient parsing is enabled.  In that case Click
+        #: will do its best to not cause any failures and default values
+        #: will be ignored. Useful for completion.
+        self.resilient_parsing = resilient_parsing
+
+        # If there is no envvar prefix yet, but the parent has one and
+        # the command on this level has a name, we can expand the envvar
+        # prefix automatically.
+        if auto_envvar_prefix is None:
+            if parent is not None \
+               and parent.auto_envvar_prefix is not None and \
+               self.info_name is not None:
+                auto_envvar_prefix = '%s_%s' % (parent.auto_envvar_prefix,
+                                           self.info_name.upper())
+        else:
+            auto_envvar_prefix = auto_envvar_prefix.upper()
+        self.auto_envvar_prefix = auto_envvar_prefix
+
+        if color is None and parent is not None:
+            color = parent.color
+
+        #: Controls if styling output is wanted or not.
+        self.color = color
+
+        self._close_callbacks = []
+        self._depth = 0
+
+    def __enter__(self):
+        self._depth += 1
+        push_context(self)
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self._depth -= 1
+        if self._depth == 0:
+            self.close()
+        pop_context()
+
+    @contextmanager
+    def scope(self, cleanup=True):
+        """This helper method can be used with the context object to promote
+        it to the current thread local (see :func:`get_current_context`).
+        The default behavior of this is to invoke the cleanup functions which
+        can be disabled by setting `cleanup` to `False`.  The cleanup
+        functions are typically used for things such as closing file handles.
+
+        If the cleanup is intended the context object can also be directly
+        used as a context manager.
+
+        Example usage::
+
+            with ctx.scope():
+                assert get_current_context() is ctx
+
+        This is equivalent::
+
+            with ctx:
+                assert get_current_context() is ctx
+
+        .. versionadded:: 5.0
+
+        :param cleanup: controls if the cleanup functions should be run or
+                        not.  The default is to run these functions.  In
+                        some situations the context only wants to be
+                        temporarily pushed in which case this can be disabled.
+                        Nested pushes automatically defer the cleanup.
+        """
+        if not cleanup:
+            self._depth += 1
+        try:
+            with self as rv:
+                yield rv
+        finally:
+            if not cleanup:
+                self._depth -= 1
+
+    @property
+    def meta(self):
+        """This is a dictionary which is shared with all the contexts
+        that are nested.  It exists so that click utilities can store some
+        state here if they need to.  It is however the responsibility of
+        that code to manage this dictionary well.
+
+        The keys are supposed to be unique dotted strings.  For instance
+        module paths are a good choice for it.  What is stored in there is
+        irrelevant for the operation of click.  However what is important is
+        that code that places data here adheres to the general semantics of
+        the system.
+
+        Example usage::
+
+            LANG_KEY = __name__ + '.lang'
+
+            def set_language(value):
+                ctx = get_current_context()
+                ctx.meta[LANG_KEY] = value
+
+            def get_language():
+                return get_current_context().meta.get(LANG_KEY, 'en_US')
+
+        .. versionadded:: 5.0
+        """
+        return self._meta
+
+    def make_formatter(self):
+        """Creates the formatter for the help and usage output."""
+        return HelpFormatter(width=self.terminal_width,
+                             max_width=self.max_content_width)
+
+    def call_on_close(self, f):
+        """This decorator remembers a function as callback that should be
+        executed when the context tears down.  This is most useful to bind
+        resource handling to the script execution.  For instance, file objects
+        opened by the :class:`File` type will register their close callbacks
+        here.
+
+        :param f: the function to execute on teardown.
+        """
+        self._close_callbacks.append(f)
+        return f
+
+    def close(self):
+        """Invokes all close callbacks."""
+        for cb in self._close_callbacks:
+            cb()
+        self._close_callbacks = []
+
+    @property
+    def command_path(self):
+        """The computed command path.  This is used for the ``usage``
+        information on the help page.  It's automatically created by
+        combining the info names of the chain of contexts to the root.
+        """
+        rv = ''
+        if self.info_name is not None:
+            rv = self.info_name
+        if self.parent is not None:
+            rv = self.parent.command_path + ' ' + rv
+        return rv.lstrip()
+
+    def find_root(self):
+        """Finds the outermost context."""
+        node = self
+        while node.parent is not None:
+            node = node.parent
+        return node
+
+    def find_object(self, object_type):
+        """Finds the closest object of a given type."""
+        node = self
+        while node is not None:
+            if isinstance(node.obj, object_type):
+                return node.obj
+            node = node.parent
+
+    def ensure_object(self, object_type):
+        """Like :meth:`find_object` but sets the innermost object to a
+        new instance of `object_type` if it does not exist.
+        """
+        rv = self.find_object(object_type)
+        if rv is None:
+            self.obj = rv = object_type()
+        return rv
+
+    def lookup_default(self, name):
+        """Looks up the default for a parameter name.  This by default
+        looks into the :attr:`default_map` if available.
+        """
+        if self.default_map is not None:
+            rv = self.default_map.get(name)
+            if callable(rv):
+                rv = rv()
+            return rv
+
+    def fail(self, message):
+        """Aborts the execution of the program with a specific error
+        message.
+
+        :param message: the error message to fail with.
+        """
+        raise UsageError(message, self)
+
+    def abort(self):
+        """Aborts the script."""
+        raise Abort()
+
+    def exit(self, code=0):
+        """Exits the application with a given exit code."""
+        raise Exit(code)
+
+    def get_usage(self):
+        """Helper method to get formatted usage string for the current
+        context and command.
+        """
+        return self.command.get_usage(self)
+
+    def get_help(self):
+        """Helper method to get formatted help page for the current
+        context and command.
+        """
+        return self.command.get_help(self)
+
+    def invoke(*args, **kwargs):
+        """Invokes a command callback in exactly the way it expects.  There
+        are two ways to invoke this method:
+
+        1.  the first argument can be a callback and all other arguments and
+            keyword arguments are forwarded directly to the function.
+        2.  the first argument is a click command object.  In that case all
+            arguments are forwarded as well but proper click parameters
+            (options and click arguments) must be keyword arguments and Click
+            will fill in defaults.
+
+        Note that before Click 3.2 keyword arguments were not properly filled
+        in against the intention of this code and no context was created.  For
+        more information about this change and why it was done in a bugfix
+        release see :ref:`upgrade-to-3.2`.
+        """
+        self, callback = args[:2]
+        ctx = self
+
+        # It's also possible to invoke another command which might or
+        # might not have a callback.  In that case we also fill
+        # in defaults and make a new context for this command.
+        if isinstance(callback, Command):
+            other_cmd = callback
+            callback = other_cmd.callback
+            ctx = Context(other_cmd, info_name=other_cmd.name, parent=self)
+            if callback is None:
+                raise TypeError('The given command does not have a '
+                                'callback that can be invoked.')
+
+            for param in other_cmd.params:
+                if param.name not in kwargs and param.expose_value:
+                    kwargs[param.name] = param.get_default(ctx)
+
+        args = args[2:]
+        with augment_usage_errors(self):
+            with ctx:
+                return callback(*args, **kwargs)
+
+    def forward(*args, **kwargs):
+        """Similar to :meth:`invoke` but fills in default keyword
+        arguments from the current context if the other command expects
+        it.  This cannot invoke callbacks directly, only other commands.
+        """
+        self, cmd = args[:2]
+
+        # It's also possible to invoke another command which might or
+        # might not have a callback.
+        if not isinstance(cmd, Command):
+            raise TypeError('Callback is not a command.')
+
+        for param in self.params:
+            if param not in kwargs:
+                kwargs[param] = self.params[param]
+
+        return self.invoke(cmd, **kwargs)
+
+
+class BaseCommand(object):
+    """The base command implements the minimal API contract of commands.
+    Most code will never use this as it does not implement a lot of useful
+    functionality but it can act as the direct subclass of alternative
+    parsing methods that do not depend on the Click parser.
+
+    For instance, this can be used to bridge Click and other systems like
+    argparse or docopt.
+
+    Because base commands do not implement a lot of the API that other
+    parts of Click take for granted, they are not supported for all
+    operations.  For instance, they cannot be used with the decorators
+    usually and they have no built-in callback system.
+
+    .. versionchanged:: 2.0
+       Added the `context_settings` parameter.
+
+    :param name: the name of the command to use unless a group overrides it.
+    :param context_settings: an optional dictionary with defaults that are
+                             passed to the context object.
+    """
+    #: the default for the :attr:`Context.allow_extra_args` flag.
+    allow_extra_args = False
+    #: the default for the :attr:`Context.allow_interspersed_args` flag.
+    allow_interspersed_args = True
+    #: the default for the :attr:`Context.ignore_unknown_options` flag.
+    ignore_unknown_options = False
+
+    def __init__(self, name, context_settings=None):
+        #: the name the command thinks it has.  Upon registering a command
+        #: on a :class:`Group` the group will default the command name
+        #: with this information.  You should instead use the
+        #: :class:`Context`\'s :attr:`~Context.info_name` attribute.
+        self.name = name
+        if context_settings is None:
+            context_settings = {}
+        #: an optional dictionary with defaults passed to the context.
+        self.context_settings = context_settings
+
+    def get_usage(self, ctx):
+        raise NotImplementedError('Base commands cannot get usage')
+
+    def get_help(self, ctx):
+        raise NotImplementedError('Base commands cannot get help')
+
+    def make_context(self, info_name, args, parent=None, **extra):
+        """This function when given an info name and arguments will kick
+        off the parsing and create a new :class:`Context`.  It does not
+        invoke the actual command callback though.
+
+        :param info_name: the info name for this invokation.  Generally this
+                          is the most descriptive name for the script or
+                          command.  For the toplevel script it's usually
+                          the name of the script, for commands below it it's
+                          the name of the script.
+        :param args: the arguments to parse as list of strings.
+        :param parent: the parent context if available.
+        :param extra: extra keyword arguments forwarded to the context
+                      constructor.
+        """
+        for key, value in iteritems(self.context_settings):
+            if key not in extra:
+                extra[key] = value
+        ctx = Context(self, info_name=info_name, parent=parent, **extra)
+        with ctx.scope(cleanup=False):
+            self.parse_args(ctx, args)
+        return ctx
+
+    def parse_args(self, ctx, args):
+        """Given a context and a list of arguments this creates the parser
+        and parses the arguments, then modifies the context as necessary.
+        This is automatically invoked by :meth:`make_context`.
+        """
+        raise NotImplementedError('Base commands do not know how to parse '
+                                  'arguments.')
+
+    def invoke(self, ctx):
+        """Given a context, this invokes the command.  The default
+        implementation is raising a not implemented error.
+        """
+        raise NotImplementedError('Base commands are not invokable by default')
+
+    def main(self, args=None, prog_name=None, complete_var=None,
+             standalone_mode=True, **extra):
+        """This is the way to invoke a script with all the bells and
+        whistles as a command line application.  This will always terminate
+        the application after a call.  If this is not wanted, ``SystemExit``
+        needs to be caught.
+
+        This method is also available by directly calling the instance of
+        a :class:`Command`.
+
+        .. versionadded:: 3.0
+           Added the `standalone_mode` flag to control the standalone mode.
+
+        :param args: the arguments that should be used for parsing.  If not
+                     provided, ``sys.argv[1:]`` is used.
+        :param prog_name: the program name that should be used.  By default
+                          the program name is constructed by taking the file
+                          name from ``sys.argv[0]``.
+        :param complete_var: the environment variable that controls the
+                             bash completion support.  The default is
+                             ``"_<prog_name>_COMPLETE"`` with prog_name in
+                             uppercase.
+        :param standalone_mode: the default behavior is to invoke the script
+                                in standalone mode.  Click will then
+                                handle exceptions and convert them into
+                                error messages and the function will never
+                                return but shut down the interpreter.  If
+                                this is set to `False` they will be
+                                propagated to the caller and the return
+                                value of this function is the return value
+                                of :meth:`invoke`.
+        :param extra: extra keyword arguments are forwarded to the context
+                      constructor.  See :class:`Context` for more information.
+        """
+        # If we are in Python 3, we will verify that the environment is
+        # sane at this point or reject further execution to avoid a
+        # broken script.
+        if not PY2:
+            _verify_python3_env()
+        else:
+            _check_for_unicode_literals()
+
+        if args is None:
+            args = get_os_args()
+        else:
+            args = list(args)
+
+        if prog_name is None:
+            prog_name = make_str(os.path.basename(
+                sys.argv and sys.argv[0] or __file__))
+
+        # Hook for the Bash completion.  This only activates if the Bash
+        # completion is actually enabled, otherwise this is quite a fast
+        # noop.
+        _bashcomplete(self, prog_name, complete_var)
+
+        try:
+            try:
+                with self.make_context(prog_name, args, **extra) as ctx:
+                    rv = self.invoke(ctx)
+                    if not standalone_mode:
+                        return rv
+                    # it's not safe to `ctx.exit(rv)` here!
+                    # note that `rv` may actually contain data like "1" which
+                    # has obvious effects
+                    # more subtle case: `rv=[None, None]` can come out of
+                    # chained commands which all returned `None` -- so it's not
+                    # even always obvious that `rv` indicates success/failure
+                    # by its truthiness/falsiness
+                    ctx.exit()
+            except (EOFError, KeyboardInterrupt):
+                echo(file=sys.stderr)
+                raise Abort()
+            except ClickException as e:
+                if not standalone_mode:
+                    raise
+                e.show()
+                sys.exit(e.exit_code)
+            except IOError as e:
+                if e.errno == errno.EPIPE:
+                    sys.stdout = PacifyFlushWrapper(sys.stdout)
+                    sys.stderr = PacifyFlushWrapper(sys.stderr)
+                    sys.exit(1)
+                else:
+                    raise
+        except Exit as e:
+            if standalone_mode:
+                sys.exit(e.exit_code)
+            else:
+                # in non-standalone mode, return the exit code
+                # note that this is only reached if `self.invoke` above raises
+                # an Exit explicitly -- thus bypassing the check there which
+                # would return its result
+                # the results of non-standalone execution may therefore be
+                # somewhat ambiguous: if there are codepaths which lead to
+                # `ctx.exit(1)` and to `return 1`, the caller won't be able to
+                # tell the difference between the two
+                return e.exit_code
+        except Abort:
+            if not standalone_mode:
+                raise
+            echo('Aborted!', file=sys.stderr)
+            sys.exit(1)
+
+    def __call__(self, *args, **kwargs):
+        """Alias for :meth:`main`."""
+        return self.main(*args, **kwargs)
+
+
+class Command(BaseCommand):
+    """Commands are the basic building block of command line interfaces in
+    Click.  A basic command handles command line parsing and might dispatch
+    more parsing to commands nested below it.
+
+    .. versionchanged:: 2.0
+       Added the `context_settings` parameter.
+
+    :param name: the name of the command to use unless a group overrides it.
+    :param context_settings: an optional dictionary with defaults that are
+                             passed to the context object.
+    :param callback: the callback to invoke.  This is optional.
+    :param params: the parameters to register with this command.  This can
+                   be either :class:`Option` or :class:`Argument` objects.
+    :param help: the help string to use for this command.
+    :param epilog: like the help string but it's printed at the end of the
+                   help page after everything else.
+    :param short_help: the short help to use for this command.  This is
+                       shown on the command listing of the parent command.
+    :param add_help_option: by default each command registers a ``--help``
+                            option.  This can be disabled by this parameter.
+    :param hidden: hide this command from help outputs.
+
+    :param deprecated: issues a message indicating that
+                             the command is deprecated.
+    """
+
+    def __init__(self, name, context_settings=None, callback=None,
+                 params=None, help=None, epilog=None, short_help=None,
+                 options_metavar='[OPTIONS]', add_help_option=True,
+                 hidden=False, deprecated=False):
+        BaseCommand.__init__(self, name, context_settings)
+        #: the callback to execute when the command fires.  This might be
+        #: `None` in which case nothing happens.
+        self.callback = callback
+        #: the list of parameters for this command in the order they
+        #: should show up in the help page and execute.  Eager parameters
+        #: will automatically be handled before non eager ones.
+        self.params = params or []
+        # if a form feed (page break) is found in the help text, truncate help
+        # text to the content preceding the first form feed
+        if help and '\f' in help:
+            help = help.split('\f', 1)[0]
+        self.help = help
+        self.epilog = epilog
+        self.options_metavar = options_metavar
+        self.short_help = short_help
+        self.add_help_option = add_help_option
+        self.hidden = hidden
+        self.deprecated = deprecated
+
+    def get_usage(self, ctx):
+        formatter = ctx.make_formatter()
+        self.format_usage(ctx, formatter)
+        return formatter.getvalue().rstrip('\n')
+
+    def get_params(self, ctx):
+        rv = self.params
+        help_option = self.get_help_option(ctx)
+        if help_option is not None:
+            rv = rv + [help_option]
+        return rv
+
+    def format_usage(self, ctx, formatter):
+        """Writes the usage line into the formatter."""
+        pieces = self.collect_usage_pieces(ctx)
+        formatter.write_usage(ctx.command_path, ' '.join(pieces))
+
+    def collect_usage_pieces(self, ctx):
+        """Returns all the pieces that go into the usage line and returns
+        it as a list of strings.
+        """
+        rv = [self.options_metavar]
+        for param in self.get_params(ctx):
+            rv.extend(param.get_usage_pieces(ctx))
+        return rv
+
+    def get_help_option_names(self, ctx):
+        """Returns the names for the help option."""
+        all_names = set(ctx.help_option_names)
+        for param in self.params:
+            all_names.difference_update(param.opts)
+            all_names.difference_update(param.secondary_opts)
+        return all_names
+
+    def get_help_option(self, ctx):
+        """Returns the help option object."""
+        help_options = self.get_help_option_names(ctx)
+        if not help_options or not self.add_help_option:
+            return
+
+        def show_help(ctx, param, value):
+            if value and not ctx.resilient_parsing:
+                echo(ctx.get_help(), color=ctx.color)
+                ctx.exit()
+        return Option(help_options, is_flag=True,
+                      is_eager=True, expose_value=False,
+                      callback=show_help,
+                      help='Show this message and exit.')
+
+    def make_parser(self, ctx):
+        """Creates the underlying option parser for this command."""
+        parser = OptionParser(ctx)
+        for param in self.get_params(ctx):
+            param.add_to_parser(parser, ctx)
+        return parser
+
+    def get_help(self, ctx):
+        """Formats the help into a string and returns it.  This creates a
+        formatter and will call into the following formatting methods:
+        """
+        formatter = ctx.make_formatter()
+        self.format_help(ctx, formatter)
+        return formatter.getvalue().rstrip('\n')
+
+    def get_short_help_str(self, limit=45):
+        """Gets short help for the command or makes it by shortening the long help string."""
+        return self.short_help or self.help and make_default_short_help(self.help, limit) or ''
+
+    def format_help(self, ctx, formatter):
+        """Writes the help into the formatter if it exists.
+
+        This calls into the following methods:
+
+        -   :meth:`format_usage`
+        -   :meth:`format_help_text`
+        -   :meth:`format_options`
+        -   :meth:`format_epilog`
+        """
+        self.format_usage(ctx, formatter)
+        self.format_help_text(ctx, formatter)
+        self.format_options(ctx, formatter)
+        self.format_epilog(ctx, formatter)
+
+    def format_help_text(self, ctx, formatter):
+        """Writes the help text to the formatter if it exists."""
+        if self.help:
+            formatter.write_paragraph()
+            with formatter.indentation():
+                help_text = self.help
+                if self.deprecated:
+                    help_text += DEPRECATED_HELP_NOTICE
+                formatter.write_text(help_text)
+        elif self.deprecated:
+            formatter.write_paragraph()
+            with formatter.indentation():
+                formatter.write_text(DEPRECATED_HELP_NOTICE)
+
+    def format_options(self, ctx, formatter):
+        """Writes all the options into the formatter if they exist."""
+        opts = []
+        for param in self.get_params(ctx):
+            rv = param.get_help_record(ctx)
+            if rv is not None:
+                opts.append(rv)
+
+        if opts:
+            with formatter.section('Options'):
+                formatter.write_dl(opts)
+
+    def format_epilog(self, ctx, formatter):
+        """Writes the epilog into the formatter if it exists."""
+        if self.epilog:
+            formatter.write_paragraph()
+            with formatter.indentation():
+                formatter.write_text(self.epilog)
+
+    def parse_args(self, ctx, args):
+        parser = self.make_parser(ctx)
+        opts, args, param_order = parser.parse_args(args=args)
+
+        for param in iter_params_for_processing(
+                param_order, self.get_params(ctx)):
+            value, args = param.handle_parse_result(ctx, opts, args)
+
+        if args and not ctx.allow_extra_args and not ctx.resilient_parsing:
+            ctx.fail('Got unexpected extra argument%s (%s)'
+                     % (len(args) != 1 and 's' or '',
+                        ' '.join(map(make_str, args))))
+
+        ctx.args = args
+        return args
+
+    def invoke(self, ctx):
+        """Given a context, this invokes the attached callback (if it exists)
+        in the right way.
+        """
+        _maybe_show_deprecated_notice(self)
+        if self.callback is not None:
+            return ctx.invoke(self.callback, **ctx.params)
+
+
+class MultiCommand(Command):
+    """A multi command is the basic implementation of a command that
+    dispatches to subcommands.  The most common version is the
+    :class:`Group`.
+
+    :param invoke_without_command: this controls how the multi command itself
+                                   is invoked.  By default it's only invoked
+                                   if a subcommand is provided.
+    :param no_args_is_help: this controls what happens if no arguments are
+                            provided.  This option is enabled by default if
+                            `invoke_without_command` is disabled or disabled
+                            if it's enabled.  If enabled this will add
+                            ``--help`` as argument if no arguments are
+                            passed.
+    :param subcommand_metavar: the string that is used in the documentation
+                               to indicate the subcommand place.
+    :param chain: if this is set to `True` chaining of multiple subcommands
+                  is enabled.  This restricts the form of commands in that
+                  they cannot have optional arguments but it allows
+                  multiple commands to be chained together.
+    :param result_callback: the result callback to attach to this multi
+                            command.
+    """
+    allow_extra_args = True
+    allow_interspersed_args = False
+
+    def __init__(self, name=None, invoke_without_command=False,
+                 no_args_is_help=None, subcommand_metavar=None,
+                 chain=False, result_callback=None, **attrs):
+        Command.__init__(self, name, **attrs)
+        if no_args_is_help is None:
+            no_args_is_help = not invoke_without_command
+        self.no_args_is_help = no_args_is_help
+        self.invoke_without_command = invoke_without_command
+        if subcommand_metavar is None:
+            if chain:
+                subcommand_metavar = SUBCOMMANDS_METAVAR
+            else:
+                subcommand_metavar = SUBCOMMAND_METAVAR
+        self.subcommand_metavar = subcommand_metavar
+        self.chain = chain
+        #: The result callback that is stored.  This can be set or
+        #: overridden with the :func:`resultcallback` decorator.
+        self.result_callback = result_callback
+
+        if self.chain:
+            for param in self.params:
+                if isinstance(param, Argument) and not param.required:
+                    raise RuntimeError('Multi commands in chain mode cannot '
+                                       'have optional arguments.')
+
+    def collect_usage_pieces(self, ctx):
+        rv = Command.collect_usage_pieces(self, ctx)
+        rv.append(self.subcommand_metavar)
+        return rv
+
+    def format_options(self, ctx, formatter):
+        Command.format_options(self, ctx, formatter)
+        self.format_commands(ctx, formatter)
+
+    def resultcallback(self, replace=False):
+        """Adds a result callback to the chain command.  By default if a
+        result callback is already registered this will chain them but
+        this can be disabled with the `replace` parameter.  The result
+        callback is invoked with the return value of the subcommand
+        (or the list of return values from all subcommands if chaining
+        is enabled) as well as the parameters as they would be passed
+        to the main callback.
+
+        Example::
+
+            @click.group()
+            @click.option('-i', '--input', default=23)
+            def cli(input):
+                return 42
+
+            @cli.resultcallback()
+            def process_result(result, input):
+                return result + input
+
+        .. versionadded:: 3.0
+
+        :param replace: if set to `True` an already existing result
+                        callback will be removed.
+        """
+        def decorator(f):
+            old_callback = self.result_callback
+            if old_callback is None or replace:
+                self.result_callback = f
+                return f
+            def function(__value, *args, **kwargs):
+                return f(old_callback(__value, *args, **kwargs),
+                         *args, **kwargs)
+            self.result_callback = rv = update_wrapper(function, f)
+            return rv
+        return decorator
+
+    def format_commands(self, ctx, formatter):
+        """Extra format methods for multi methods that adds all the commands
+        after the options.
+        """
+        commands = []
+        for subcommand in self.list_commands(ctx):
+            cmd = self.get_command(ctx, subcommand)
+            # What is this, the tool lied about a command.  Ignore it
+            if cmd is None:
+                continue
+            if cmd.hidden:
+                continue
+
+            commands.append((subcommand, cmd))
+
+        # allow for 3 times the default spacing
+        if len(commands):
+            limit = formatter.width - 6 - max(len(cmd[0]) for cmd in commands)
+
+            rows = []
+            for subcommand, cmd in commands:
+                help = cmd.get_short_help_str(limit)
+                rows.append((subcommand, help))
+
+            if rows:
+                with formatter.section('Commands'):
+                    formatter.write_dl(rows)
+
+    def parse_args(self, ctx, args):
+        if not args and self.no_args_is_help and not ctx.resilient_parsing:
+            echo(ctx.get_help(), color=ctx.color)
+            ctx.exit()
+
+        rest = Command.parse_args(self, ctx, args)
+        if self.chain:
+            ctx.protected_args = rest
+            ctx.args = []
+        elif rest:
+            ctx.protected_args, ctx.args = rest[:1], rest[1:]
+
+        return ctx.args
+
+    def invoke(self, ctx):
+        def _process_result(value):
+            if self.result_callback is not None:
+                value = ctx.invoke(self.result_callback, value,
+                                   **ctx.params)
+            return value
+
+        if not ctx.protected_args:
+            # If we are invoked without command the chain flag controls
+            # how this happens.  If we are not in chain mode, the return
+            # value here is the return value of the command.
+            # If however we are in chain mode, the return value is the
+            # return value of the result processor invoked with an empty
+            # list (which means that no subcommand actually was executed).
+            if self.invoke_without_command:
+                if not self.chain:
+                    return Command.invoke(self, ctx)
+                with ctx:
+                    Command.invoke(self, ctx)
+                    return _process_result([])
+            ctx.fail('Missing command.')
+
+        # Fetch args back out
+        args = ctx.protected_args + ctx.args
+        ctx.args = []
+        ctx.protected_args = []
+
+        # If we're not in chain mode, we only allow the invocation of a
+        # single command but we also inform the current context about the
+        # name of the command to invoke.
+        if not self.chain:
+            # Make sure the context is entered so we do not clean up
+            # resources until the result processor has worked.
+            with ctx:
+                cmd_name, cmd, args = self.resolve_command(ctx, args)
+                ctx.invoked_subcommand = cmd_name
+                Command.invoke(self, ctx)
+                sub_ctx = cmd.make_context(cmd_name, args, parent=ctx)
+                with sub_ctx:
+                    return _process_result(sub_ctx.command.invoke(sub_ctx))
+
+        # In chain mode we create the contexts step by step, but after the
+        # base command has been invoked.  Because at that point we do not
+        # know the subcommands yet, the invoked subcommand attribute is
+        # set to ``*`` to inform the command that subcommands are executed
+        # but nothing else.
+        with ctx:
+            ctx.invoked_subcommand = args and '*' or None
+            Command.invoke(self, ctx)
+
+            # Otherwise we make every single context and invoke them in a
+            # chain.  In that case the return value to the result processor
+            # is the list of all invoked subcommand's results.
+            contexts = []
+            while args:
+                cmd_name, cmd, args = self.resolve_command(ctx, args)
+                sub_ctx = cmd.make_context(cmd_name, args, parent=ctx,
+                                           allow_extra_args=True,
+                                           allow_interspersed_args=False)
+                contexts.append(sub_ctx)
+                args, sub_ctx.args = sub_ctx.args, []
+
+            rv = []
+            for sub_ctx in contexts:
+                with sub_ctx:
+                    rv.append(sub_ctx.command.invoke(sub_ctx))
+            return _process_result(rv)
+
+    def resolve_command(self, ctx, args):
+        cmd_name = make_str(args[0])
+        original_cmd_name = cmd_name
+
+        # Get the command
+        cmd = self.get_command(ctx, cmd_name)
+
+        # If we can't find the command but there is a normalization
+        # function available, we try with that one.
+        if cmd is None and ctx.token_normalize_func is not None:
+            cmd_name = ctx.token_normalize_func(cmd_name)
+            cmd = self.get_command(ctx, cmd_name)
+
+        # If we don't find the command we want to show an error message
+        # to the user that it was not provided.  However, there is
+        # something else we should do: if the first argument looks like
+        # an option we want to kick off parsing again for arguments to
+        # resolve things like --help which now should go to the main
+        # place.
+        if cmd is None and not ctx.resilient_parsing:
+            if split_opt(cmd_name)[0]:
+                self.parse_args(ctx, ctx.args)
+            ctx.fail('No such command "%s".' % original_cmd_name)
+
+        return cmd_name, cmd, args[1:]
+
+    def get_command(self, ctx, cmd_name):
+        """Given a context and a command name, this returns a
+        :class:`Command` object if it exists or returns `None`.
+        """
+        raise NotImplementedError()
+
+    def list_commands(self, ctx):
+        """Returns a list of subcommand names in the order they should
+        appear.
+        """
+        return []
+
+
+class Group(MultiCommand):
+    """A group allows a command to have subcommands attached.  This is the
+    most common way to implement nesting in Click.
+
+    :param commands: a dictionary of commands.
+    """
+
+    def __init__(self, name=None, commands=None, **attrs):
+        MultiCommand.__init__(self, name, **attrs)
+        #: the registered subcommands by their exported names.
+        self.commands = commands or {}
+
+    def add_command(self, cmd, name=None):
+        """Registers another :class:`Command` with this group.  If the name
+        is not provided, the name of the command is used.
+        """
+        name = name or cmd.name
+        if name is None:
+            raise TypeError('Command has no name.')
+        _check_multicommand(self, name, cmd, register=True)
+        self.commands[name] = cmd
+
+    def command(self, *args, **kwargs):
+        """A shortcut decorator for declaring and attaching a command to
+        the group.  This takes the same arguments as :func:`command` but
+        immediately registers the created command with this instance by
+        calling into :meth:`add_command`.
+        """
+        def decorator(f):
+            cmd = command(*args, **kwargs)(f)
+            self.add_command(cmd)
+            return cmd
+        return decorator
+
+    def group(self, *args, **kwargs):
+        """A shortcut decorator for declaring and attaching a group to
+        the group.  This takes the same arguments as :func:`group` but
+        immediately registers the created command with this instance by
+        calling into :meth:`add_command`.
+        """
+        def decorator(f):
+            cmd = group(*args, **kwargs)(f)
+            self.add_command(cmd)
+            return cmd
+        return decorator
+
+    def get_command(self, ctx, cmd_name):
+        return self.commands.get(cmd_name)
+
+    def list_commands(self, ctx):
+        return sorted(self.commands)
+
+
+class CommandCollection(MultiCommand):
+    """A command collection is a multi command that merges multiple multi
+    commands together into one.  This is a straightforward implementation
+    that accepts a list of different multi commands as sources and
+    provides all the commands for each of them.
+    """
+
+    def __init__(self, name=None, sources=None, **attrs):
+        MultiCommand.__init__(self, name, **attrs)
+        #: The list of registered multi commands.
+        self.sources = sources or []
+
+    def add_source(self, multi_cmd):
+        """Adds a new multi command to the chain dispatcher."""
+        self.sources.append(multi_cmd)
+
+    def get_command(self, ctx, cmd_name):
+        for source in self.sources:
+            rv = source.get_command(ctx, cmd_name)
+            if rv is not None:
+                if self.chain:
+                    _check_multicommand(self, cmd_name, rv)
+                return rv
+
+    def list_commands(self, ctx):
+        rv = set()
+        for source in self.sources:
+            rv.update(source.list_commands(ctx))
+        return sorted(rv)
+
+
+class Parameter(object):
+    r"""A parameter to a command comes in two versions: they are either
+    :class:`Option`\s or :class:`Argument`\s.  Other subclasses are currently
+    not supported by design as some of the internals for parsing are
+    intentionally not finalized.
+
+    Some settings are supported by both options and arguments.
+
+    .. versionchanged:: 2.0
+       Changed signature for parameter callback to also be passed the
+       parameter.  In Click 2.0, the old callback format will still work,
+       but it will raise a warning to give you change to migrate the
+       code easier.
+
+    :param param_decls: the parameter declarations for this option or
+                        argument.  This is a list of flags or argument
+                        names.
+    :param type: the type that should be used.  Either a :class:`ParamType`
+                 or a Python type.  The later is converted into the former
+                 automatically if supported.
+    :param required: controls if this is optional or not.
+    :param default: the default value if omitted.  This can also be a callable,
+                    in which case it's invoked when the default is needed
+                    without any arguments.
+    :param callback: a callback that should be executed after the parameter
+                     was matched.  This is called as ``fn(ctx, param,
+                     value)`` and needs to return the value.  Before Click
+                     2.0, the signature was ``(ctx, value)``.
+    :param nargs: the number of arguments to match.  If not ``1`` the return
+                  value is a tuple instead of single value.  The default for
+                  nargs is ``1`` (except if the type is a tuple, then it's
+                  the arity of the tuple).
+    :param metavar: how the value is represented in the help page.
+    :param expose_value: if this is `True` then the value is passed onwards
+                         to the command callback and stored on the context,
+                         otherwise it's skipped.
+    :param is_eager: eager values are processed before non eager ones.  This
+                     should not be set for arguments or it will inverse the
+                     order of processing.
+    :param envvar: a string or list of strings that are environment variables
+                   that should be checked.
+    """
+    param_type_name = 'parameter'
+
+    def __init__(self, param_decls=None, type=None, required=False,
+                 default=None, callback=None, nargs=None, metavar=None,
+                 expose_value=True, is_eager=False, envvar=None,
+                 autocompletion=None):
+        self.name, self.opts, self.secondary_opts = \
+            self._parse_decls(param_decls or (), expose_value)
+
+        self.type = convert_type(type, default)
+
+        # Default nargs to what the type tells us if we have that
+        # information available.
+        if nargs is None:
+            if self.type.is_composite:
+                nargs = self.type.arity
+            else:
+                nargs = 1
+
+        self.required = required
+        self.callback = callback
+        self.nargs = nargs
+        self.multiple = False
+        self.expose_value = expose_value
+        self.default = default
+        self.is_eager = is_eager
+        self.metavar = metavar
+        self.envvar = envvar
+        self.autocompletion = autocompletion
+
+    @property
+    def human_readable_name(self):
+        """Returns the human readable name of this parameter.  This is the
+        same as the name for options, but the metavar for arguments.
+        """
+        return self.name
+
+    def make_metavar(self):
+        if self.metavar is not None:
+            return self.metavar
+        metavar = self.type.get_metavar(self)
+        if metavar is None:
+            metavar = self.type.name.upper()
+        if self.nargs != 1:
+            metavar += '...'
+        return metavar
+
+    def get_default(self, ctx):
+        """Given a context variable this calculates the default value."""
+        # Otherwise go with the regular default.
+        if callable(self.default):
+            rv = self.default()
+        else:
+            rv = self.default
+        return self.type_cast_value(ctx, rv)
+
+    def add_to_parser(self, parser, ctx):
+        pass
+
+    def consume_value(self, ctx, opts):
+        value = opts.get(self.name)
+        if value is None:
+            value = self.value_from_envvar(ctx)
+        if value is None:
+            value = ctx.lookup_default(self.name)
+        return value
+
+    def type_cast_value(self, ctx, value):
+        """Given a value this runs it properly through the type system.
+        This automatically handles things like `nargs` and `multiple` as
+        well as composite types.
+        """
+        if self.type.is_composite:
+            if self.nargs <= 1:
+                raise TypeError('Attempted to invoke composite type '
+                                'but nargs has been set to %s.  This is '
+                                'not supported; nargs needs to be set to '
+                                'a fixed value > 1.' % self.nargs)
+            if self.multiple:
+                return tuple(self.type(x or (), self, ctx) for x in value or ())
+            return self.type(value or (), self, ctx)
+
+        def _convert(value, level):
+            if level == 0:
+                return self.type(value, self, ctx)
+            return tuple(_convert(x, level - 1) for x in value or ())
+        return _convert(value, (self.nargs != 1) + bool(self.multiple))
+
+    def process_value(self, ctx, value):
+        """Given a value and context this runs the logic to convert the
+        value as necessary.
+        """
+        # If the value we were given is None we do nothing.  This way
+        # code that calls this can easily figure out if something was
+        # not provided.  Otherwise it would be converted into an empty
+        # tuple for multiple invocations which is inconvenient.
+        if value is not None:
+            return self.type_cast_value(ctx, value)
+
+    def value_is_missing(self, value):
+        if value is None:
+            return True
+        if (self.nargs != 1 or self.multiple) and value == ():
+            return True
+        return False
+
+    def full_process_value(self, ctx, value):
+        value = self.process_value(ctx, value)
+
+        if value is None and not ctx.resilient_parsing:
+            value = self.get_default(ctx)
+
+        if self.required and self.value_is_missing(value):
+            raise MissingParameter(ctx=ctx, param=self)
+
+        return value
+
+    def resolve_envvar_value(self, ctx):
+        if self.envvar is None:
+            return
+        if isinstance(self.envvar, (tuple, list)):
+            for envvar in self.envvar:
+                rv = os.environ.get(envvar)
+                if rv is not None:
+                    return rv
+        else:
+            return os.environ.get(self.envvar)
+
+    def value_from_envvar(self, ctx):
+        rv = self.resolve_envvar_value(ctx)
+        if rv is not None and self.nargs != 1:
+            rv = self.type.split_envvar_value(rv)
+        return rv
+
+    def handle_parse_result(self, ctx, opts, args):
+        with augment_usage_errors(ctx, param=self):
+            value = self.consume_value(ctx, opts)
+            try:
+                value = self.full_process_value(ctx, value)
+            except Exception:
+                if not ctx.resilient_parsing:
+                    raise
+                value = None
+            if self.callback is not None:
+                try:
+                    value = invoke_param_callback(
+                        self.callback, ctx, self, value)
+                except Exception:
+                    if not ctx.resilient_parsing:
+                        raise
+
+        if self.expose_value:
+            ctx.params[self.name] = value
+        return value, args
+
+    def get_help_record(self, ctx):
+        pass
+
+    def get_usage_pieces(self, ctx):
+        return []
+
+    def get_error_hint(self, ctx):
+        """Get a stringified version of the param for use in error messages to
+        indicate which param caused the error.
+        """
+        hint_list = self.opts or [self.human_readable_name]
+        return ' / '.join('"%s"' % x for x in hint_list)
+
+
+class Option(Parameter):
+    """Options are usually optional values on the command line and
+    have some extra features that arguments don't have.
+
+    All other parameters are passed onwards to the parameter constructor.
+
+    :param show_default: controls if the default value should be shown on the
+                         help page. Normally, defaults are not shown. If this
+                         value is a string, it shows the string instead of the
+                         value. This is particularly useful for dynamic options.
+    :param show_envvar: controls if an environment variable should be shown on
+                        the help page.  Normally, environment variables
+                        are not shown.
+    :param prompt: if set to `True` or a non empty string then the user will be
+                   prompted for input.  If set to `True` the prompt will be the
+                   option name capitalized.
+    :param confirmation_prompt: if set then the value will need to be confirmed
+                                if it was prompted for.
+    :param hide_input: if this is `True` then the input on the prompt will be
+                       hidden from the user.  This is useful for password
+                       input.
+    :param is_flag: forces this option to act as a flag.  The default is
+                    auto detection.
+    :param flag_value: which value should be used for this flag if it's
+                       enabled.  This is set to a boolean automatically if
+                       the option string contains a slash to mark two options.
+    :param multiple: if this is set to `True` then the argument is accepted
+                     multiple times and recorded.  This is similar to ``nargs``
+                     in how it works but supports arbitrary number of
+                     arguments.
+    :param count: this flag makes an option increment an integer.
+    :param allow_from_autoenv: if this is enabled then the value of this
+                               parameter will be pulled from an environment
+                               variable in case a prefix is defined on the
+                               context.
+    :param help: the help string.
+    :param hidden: hide this option from help outputs.
+    """
+    param_type_name = 'option'
+
+    def __init__(self, param_decls=None, show_default=False,
+                 prompt=False, confirmation_prompt=False,
+                 hide_input=False, is_flag=None, flag_value=None,
+                 multiple=False, count=False, allow_from_autoenv=True,
+                 type=None, help=None, hidden=False, show_choices=True,
+                 show_envvar=False, **attrs):
+        default_is_missing = attrs.get('default', _missing) is _missing
+        Parameter.__init__(self, param_decls, type=type, **attrs)
+
+        if prompt is True:
+            prompt_text = self.name.replace('_', ' ').capitalize()
+        elif prompt is False:
+            prompt_text = None
+        else:
+            prompt_text = prompt
+        self.prompt = prompt_text
+        self.confirmation_prompt = confirmation_prompt
+        self.hide_input = hide_input
+        self.hidden = hidden
+
+        # Flags
+        if is_flag is None:
+            if flag_value is not None:
+                is_flag = True
+            else:
+                is_flag = bool(self.secondary_opts)
+        if is_flag and default_is_missing:
+            self.default = False
+        if flag_value is None:
+            flag_value = not self.default
+        self.is_flag = is_flag
+        self.flag_value = flag_value
+        if self.is_flag and isinstance(self.flag_value, bool) \
+           and type is None:
+            self.type = BOOL
+            self.is_bool_flag = True
+        else:
+            self.is_bool_flag = False
+
+        # Counting
+        self.count = count
+        if count:
+            if type is None:
+                self.type = IntRange(min=0)
+            if default_is_missing:
+                self.default = 0
+
+        self.multiple = multiple
+        self.allow_from_autoenv = allow_from_autoenv
+        self.help = help
+        self.show_default = show_default
+        self.show_choices = show_choices
+        self.show_envvar = show_envvar
+
+        # Sanity check for stuff we don't support
+        if __debug__:
+            if self.nargs < 0:
+                raise TypeError('Options cannot have nargs < 0')
+            if self.prompt and self.is_flag and not self.is_bool_flag:
+                raise TypeError('Cannot prompt for flags that are not bools.')
+            if not self.is_bool_flag and self.secondary_opts:
+                raise TypeError('Got secondary option for non boolean flag.')
+            if self.is_bool_flag and self.hide_input \
+               and self.prompt is not None:
+                raise TypeError('Hidden input does not work with boolean '
+                                'flag prompts.')
+            if self.count:
+                if self.multiple:
+                    raise TypeError('Options cannot be multiple and count '
+                                    'at the same time.')
+                elif self.is_flag:
+                    raise TypeError('Options cannot be count and flags at '
+                                    'the same time.')
+
+    def _parse_decls(self, decls, expose_value):
+        opts = []
+        secondary_opts = []
+        name = None
+        possible_names = []
+
+        for decl in decls:
+            if isidentifier(decl):
+                if name is not None:
+                    raise TypeError('Name defined twice')
+                name = decl
+            else:
+                split_char = decl[:1] == '/' and ';' or '/'
+                if split_char in decl:
+                    first, second = decl.split(split_char, 1)
+                    first = first.rstrip()
+                    if first:
+                        possible_names.append(split_opt(first))
+                        opts.append(first)
+                    second = second.lstrip()
+                    if second:
+                        secondary_opts.append(second.lstrip())
+                else:
+                    possible_names.append(split_opt(decl))
+                    opts.append(decl)
+
+        if name is None and possible_names:
+            possible_names.sort(key=lambda x: -len(x[0]))  # group long options first
+            name = possible_names[0][1].replace('-', '_').lower()
+            if not isidentifier(name):
+                name = None
+
+        if name is None:
+            if not expose_value:
+                return None, opts, secondary_opts
+            raise TypeError('Could not determine name for option')
+
+        if not opts and not secondary_opts:
+            raise TypeError('No options defined but a name was passed (%s). '
+                            'Did you mean to declare an argument instead '
+                            'of an option?' % name)
+
+        return name, opts, secondary_opts
+
+    def add_to_parser(self, parser, ctx):
+        kwargs = {
+            'dest': self.name,
+            'nargs': self.nargs,
+            'obj': self,
+        }
+
+        if self.multiple:
+            action = 'append'
+        elif self.count:
+            action = 'count'
+        else:
+            action = 'store'
+
+        if self.is_flag:
+            kwargs.pop('nargs', None)
+            if self.is_bool_flag and self.secondary_opts:
+                parser.add_option(self.opts, action=action + '_const',
+                                  const=True, **kwargs)
+                parser.add_option(self.secondary_opts, action=action +
+                                  '_const', const=False, **kwargs)
+            else:
+                parser.add_option(self.opts, action=action + '_const',
+                                  const=self.flag_value,
+                                  **kwargs)
+        else:
+            kwargs['action'] = action
+            parser.add_option(self.opts, **kwargs)
+
+    def get_help_record(self, ctx):
+        if self.hidden:
+            return
+        any_prefix_is_slash = []
+
+        def _write_opts(opts):
+            rv, any_slashes = join_options(opts)
+            if any_slashes:
+                any_prefix_is_slash[:] = [True]
+            if not self.is_flag and not self.count:
+                rv += ' ' + self.make_metavar()
+            return rv
+
+        rv = [_write_opts(self.opts)]
+        if self.secondary_opts:
+            rv.append(_write_opts(self.secondary_opts))
+
+        help = self.help or ''
+        extra = []
+        if self.show_envvar:
+            envvar = self.envvar
+            if envvar is None:
+                if self.allow_from_autoenv and \
+                    ctx.auto_envvar_prefix is not None:
+                    envvar = '%s_%s' % (ctx.auto_envvar_prefix, self.name.upper())
+            if envvar is not None:
+              extra.append('env var: %s' % (
+                           ', '.join('%s' % d for d in envvar)
+                           if isinstance(envvar, (list, tuple))
+                           else envvar, ))
+        if self.default is not None and self.show_default:
+            if isinstance(self.show_default, string_types):
+                default_string = '({})'.format(self.show_default)
+            elif isinstance(self.default, (list, tuple)):
+                default_string = ', '.join('%s' % d for d in self.default)
+            elif inspect.isfunction(self.default):
+                default_string = "(dynamic)"
+            else:
+                default_string = self.default
+            extra.append('default: {}'.format(default_string))
+
+        if self.required:
+            extra.append('required')
+        if extra:
+            help = '%s[%s]' % (help and help + '  ' or '', '; '.join(extra))
+
+        return ((any_prefix_is_slash and '; ' or ' / ').join(rv), help)
+
+    def get_default(self, ctx):
+        # If we're a non boolean flag out default is more complex because
+        # we need to look at all flags in the same group to figure out
+        # if we're the the default one in which case we return the flag
+        # value as default.
+        if self.is_flag and not self.is_bool_flag:
+            for param in ctx.command.params:
+                if param.name == self.name and param.default:
+                    return param.flag_value
+            return None
+        return Parameter.get_default(self, ctx)
+
+    def prompt_for_value(self, ctx):
+        """This is an alternative flow that can be activated in the full
+        value processing if a value does not exist.  It will prompt the
+        user until a valid value exists and then returns the processed
+        value as result.
+        """
+        # Calculate the default before prompting anything to be stable.
+        default = self.get_default(ctx)
+
+        # If this is a prompt for a flag we need to handle this
+        # differently.
+        if self.is_bool_flag:
+            return confirm(self.prompt, default)
+
+        return prompt(self.prompt, default=default, type=self.type,
+                      hide_input=self.hide_input, show_choices=self.show_choices,
+                      confirmation_prompt=self.confirmation_prompt,
+                      value_proc=lambda x: self.process_value(ctx, x))
+
+    def resolve_envvar_value(self, ctx):
+        rv = Parameter.resolve_envvar_value(self, ctx)
+        if rv is not None:
+            return rv
+        if self.allow_from_autoenv and \
+           ctx.auto_envvar_prefix is not None:
+            envvar = '%s_%s' % (ctx.auto_envvar_prefix, self.name.upper())
+            return os.environ.get(envvar)
+
+    def value_from_envvar(self, ctx):
+        rv = self.resolve_envvar_value(ctx)
+        if rv is None:
+            return None
+        value_depth = (self.nargs != 1) + bool(self.multiple)
+        if value_depth > 0 and rv is not None:
+            rv = self.type.split_envvar_value(rv)
+            if self.multiple and self.nargs != 1:
+                rv = batch(rv, self.nargs)
+        return rv
+
+    def full_process_value(self, ctx, value):
+        if value is None and self.prompt is not None \
+           and not ctx.resilient_parsing:
+            return self.prompt_for_value(ctx)
+        return Parameter.full_process_value(self, ctx, value)
+
+
+class Argument(Parameter):
+    """Arguments are positional parameters to a command.  They generally
+    provide fewer features than options but can have infinite ``nargs``
+    and are required by default.
+
+    All parameters are passed onwards to the parameter constructor.
+    """
+    param_type_name = 'argument'
+
+    def __init__(self, param_decls, required=None, **attrs):
+        if required is None:
+            if attrs.get('default') is not None:
+                required = False
+            else:
+                required = attrs.get('nargs', 1) > 0
+        Parameter.__init__(self, param_decls, required=required, **attrs)
+        if self.default is not None and self.nargs < 0:
+            raise TypeError('nargs=-1 in combination with a default value '
+                            'is not supported.')
+
+    @property
+    def human_readable_name(self):
+        if self.metavar is not None:
+            return self.metavar
+        return self.name.upper()
+
+    def make_metavar(self):
+        if self.metavar is not None:
+            return self.metavar
+        var = self.type.get_metavar(self)
+        if not var:
+            var = self.name.upper()
+        if not self.required:
+            var = '[%s]' % var
+        if self.nargs != 1:
+            var += '...'
+        return var
+
+    def _parse_decls(self, decls, expose_value):
+        if not decls:
+            if not expose_value:
+                return None, [], []
+            raise TypeError('Could not determine name for argument')
+        if len(decls) == 1:
+            name = arg = decls[0]
+            name = name.replace('-', '_').lower()
+        else:
+            raise TypeError('Arguments take exactly one '
+                            'parameter declaration, got %d' % len(decls))
+        return name, [arg], []
+
+    def get_usage_pieces(self, ctx):
+        return [self.make_metavar()]
+
+    def get_error_hint(self, ctx):
+        return '"%s"' % self.make_metavar()
+
+    def add_to_parser(self, parser, ctx):
+        parser.add_argument(dest=self.name, nargs=self.nargs,
+                            obj=self)
+
+
+# Circular dependency between decorators and core
+from .decorators import command, group
diff --git a/python/click/decorators.py b/python/click/decorators.py
new file mode 100644
index 0000000..c57c530
--- /dev/null
+++ b/python/click/decorators.py
@@ -0,0 +1,311 @@
+import sys
+import inspect
+
+from functools import update_wrapper
+
+from ._compat import iteritems
+from ._unicodefun import _check_for_unicode_literals
+from .utils import echo
+from .globals import get_current_context
+
+
+def pass_context(f):
+    """Marks a callback as wanting to receive the current context
+    object as first argument.
+    """
+    def new_func(*args, **kwargs):
+        return f(get_current_context(), *args, **kwargs)
+    return update_wrapper(new_func, f)
+
+
+def pass_obj(f):
+    """Similar to :func:`pass_context`, but only pass the object on the
+    context onwards (:attr:`Context.obj`).  This is useful if that object
+    represents the state of a nested system.
+    """
+    def new_func(*args, **kwargs):
+        return f(get_current_context().obj, *args, **kwargs)
+    return update_wrapper(new_func, f)
+
+
+def make_pass_decorator(object_type, ensure=False):
+    """Given an object type this creates a decorator that will work
+    similar to :func:`pass_obj` but instead of passing the object of the
+    current context, it will find the innermost context of type
+    :func:`object_type`.
+
+    This generates a decorator that works roughly like this::
+
+        from functools import update_wrapper
+
+        def decorator(f):
+            @pass_context
+            def new_func(ctx, *args, **kwargs):
+                obj = ctx.find_object(object_type)
+                return ctx.invoke(f, obj, *args, **kwargs)
+            return update_wrapper(new_func, f)
+        return decorator
+
+    :param object_type: the type of the object to pass.
+    :param ensure: if set to `True`, a new object will be created and
+                   remembered on the context if it's not there yet.
+    """
+    def decorator(f):
+        def new_func(*args, **kwargs):
+            ctx = get_current_context()
+            if ensure:
+                obj = ctx.ensure_object(object_type)
+            else:
+                obj = ctx.find_object(object_type)
+            if obj is None:
+                raise RuntimeError('Managed to invoke callback without a '
+                                   'context object of type %r existing'
+                                   % object_type.__name__)
+            return ctx.invoke(f, obj, *args, **kwargs)
+        return update_wrapper(new_func, f)
+    return decorator
+
+
+def _make_command(f, name, attrs, cls):
+    if isinstance(f, Command):
+        raise TypeError('Attempted to convert a callback into a '
+                        'command twice.')
+    try:
+        params = f.__click_params__
+        params.reverse()
+        del f.__click_params__
+    except AttributeError:
+        params = []
+    help = attrs.get('help')
+    if help is None:
+        help = inspect.getdoc(f)
+        if isinstance(help, bytes):
+            help = help.decode('utf-8')
+    else:
+        help = inspect.cleandoc(help)
+    attrs['help'] = help
+    _check_for_unicode_literals()
+    return cls(name=name or f.__name__.lower().replace('_', '-'),
+               callback=f, params=params, **attrs)
+
+
+def command(name=None, cls=None, **attrs):
+    r"""Creates a new :class:`Command` and uses the decorated function as
+    callback.  This will also automatically attach all decorated
+    :func:`option`\s and :func:`argument`\s as parameters to the command.
+
+    The name of the command defaults to the name of the function.  If you
+    want to change that, you can pass the intended name as the first
+    argument.
+
+    All keyword arguments are forwarded to the underlying command class.
+
+    Once decorated the function turns into a :class:`Command` instance
+    that can be invoked as a command line utility or be attached to a
+    command :class:`Group`.
+
+    :param name: the name of the command.  This defaults to the function
+                 name with underscores replaced by dashes.
+    :param cls: the command class to instantiate.  This defaults to
+                :class:`Command`.
+    """
+    if cls is None:
+        cls = Command
+    def decorator(f):
+        cmd = _make_command(f, name, attrs, cls)
+        cmd.__doc__ = f.__doc__
+        return cmd
+    return decorator
+
+
+def group(name=None, **attrs):
+    """Creates a new :class:`Group` with a function as callback.  This
+    works otherwise the same as :func:`command` just that the `cls`
+    parameter is set to :class:`Group`.
+    """
+    attrs.setdefault('cls', Group)
+    return command(name, **attrs)
+
+
+def _param_memo(f, param):
+    if isinstance(f, Command):
+        f.params.append(param)
+    else:
+        if not hasattr(f, '__click_params__'):
+            f.__click_params__ = []
+        f.__click_params__.append(param)
+
+
+def argument(*param_decls, **attrs):
+    """Attaches an argument to the command.  All positional arguments are
+    passed as parameter declarations to :class:`Argument`; all keyword
+    arguments are forwarded unchanged (except ``cls``).
+    This is equivalent to creating an :class:`Argument` instance manually
+    and attaching it to the :attr:`Command.params` list.
+
+    :param cls: the argument class to instantiate.  This defaults to
+                :class:`Argument`.
+    """
+    def decorator(f):
+        ArgumentClass = attrs.pop('cls', Argument)
+        _param_memo(f, ArgumentClass(param_decls, **attrs))
+        return f
+    return decorator
+
+
+def option(*param_decls, **attrs):
+    """Attaches an option to the command.  All positional arguments are
+    passed as parameter declarations to :class:`Option`; all keyword
+    arguments are forwarded unchanged (except ``cls``).
+    This is equivalent to creating an :class:`Option` instance manually
+    and attaching it to the :attr:`Command.params` list.
+
+    :param cls: the option class to instantiate.  This defaults to
+                :class:`Option`.
+    """
+    def decorator(f):
+        # Issue 926, copy attrs, so pre-defined options can re-use the same cls=
+        option_attrs = attrs.copy()
+
+        if 'help' in option_attrs:
+            option_attrs['help'] = inspect.cleandoc(option_attrs['help'])
+        OptionClass = option_attrs.pop('cls', Option)
+        _param_memo(f, OptionClass(param_decls, **option_attrs))
+        return f
+    return decorator
+
+
+def confirmation_option(*param_decls, **attrs):
+    """Shortcut for confirmation prompts that can be ignored by passing
+    ``--yes`` as parameter.
+
+    This is equivalent to decorating a function with :func:`option` with
+    the following parameters::
+
+        def callback(ctx, param, value):
+            if not value:
+                ctx.abort()
+
+        @click.command()
+        @click.option('--yes', is_flag=True, callback=callback,
+                      expose_value=False, prompt='Do you want to continue?')
+        def dropdb():
+            pass
+    """
+    def decorator(f):
+        def callback(ctx, param, value):
+            if not value:
+                ctx.abort()
+        attrs.setdefault('is_flag', True)
+        attrs.setdefault('callback', callback)
+        attrs.setdefault('expose_value', False)
+        attrs.setdefault('prompt', 'Do you want to continue?')
+        attrs.setdefault('help', 'Confirm the action without prompting.')
+        return option(*(param_decls or ('--yes',)), **attrs)(f)
+    return decorator
+
+
+def password_option(*param_decls, **attrs):
+    """Shortcut for password prompts.
+
+    This is equivalent to decorating a function with :func:`option` with
+    the following parameters::
+
+        @click.command()
+        @click.option('--password', prompt=True, confirmation_prompt=True,
+                      hide_input=True)
+        def changeadmin(password):
+            pass
+    """
+    def decorator(f):
+        attrs.setdefault('prompt', True)
+        attrs.setdefault('confirmation_prompt', True)
+        attrs.setdefault('hide_input', True)
+        return option(*(param_decls or ('--password',)), **attrs)(f)
+    return decorator
+
+
+def version_option(version=None, *param_decls, **attrs):
+    """Adds a ``--version`` option which immediately ends the program
+    printing out the version number.  This is implemented as an eager
+    option that prints the version and exits the program in the callback.
+
+    :param version: the version number to show.  If not provided Click
+                    attempts an auto discovery via setuptools.
+    :param prog_name: the name of the program (defaults to autodetection)
+    :param message: custom message to show instead of the default
+                    (``'%(prog)s, version %(version)s'``)
+    :param others: everything else is forwarded to :func:`option`.
+    """
+    if version is None:
+        if hasattr(sys, '_getframe'):
+            module = sys._getframe(1).f_globals.get('__name__')
+        else:
+            module = ''
+
+    def decorator(f):
+        prog_name = attrs.pop('prog_name', None)
+        message = attrs.pop('message', '%(prog)s, version %(version)s')
+
+        def callback(ctx, param, value):
+            if not value or ctx.resilient_parsing:
+                return
+            prog = prog_name
+            if prog is None:
+                prog = ctx.find_root().info_name
+            ver = version
+            if ver is None:
+                try:
+                    import pkg_resources
+                except ImportError:
+                    pass
+                else:
+                    for dist in pkg_resources.working_set:
+                        scripts = dist.get_entry_map().get('console_scripts') or {}
+                        for script_name, entry_point in iteritems(scripts):
+                            if entry_point.module_name == module:
+                                ver = dist.version
+                                break
+                if ver is None:
+                    raise RuntimeError('Could not determine version')
+            echo(message % {
+                'prog': prog,
+                'version': ver,
+            }, color=ctx.color)
+            ctx.exit()
+
+        attrs.setdefault('is_flag', True)
+        attrs.setdefault('expose_value', False)
+        attrs.setdefault('is_eager', True)
+        attrs.setdefault('help', 'Show the version and exit.')
+        attrs['callback'] = callback
+        return option(*(param_decls or ('--version',)), **attrs)(f)
+    return decorator
+
+
+def help_option(*param_decls, **attrs):
+    """Adds a ``--help`` option which immediately ends the program
+    printing out the help page.  This is usually unnecessary to add as
+    this is added by default to all commands unless suppressed.
+
+    Like :func:`version_option`, this is implemented as eager option that
+    prints in the callback and exits.
+
+    All arguments are forwarded to :func:`option`.
+    """
+    def decorator(f):
+        def callback(ctx, param, value):
+            if value and not ctx.resilient_parsing:
+                echo(ctx.get_help(), color=ctx.color)
+                ctx.exit()
+        attrs.setdefault('is_flag', True)
+        attrs.setdefault('expose_value', False)
+        attrs.setdefault('help', 'Show this message and exit.')
+        attrs.setdefault('is_eager', True)
+        attrs['callback'] = callback
+        return option(*(param_decls or ('--help',)), **attrs)(f)
+    return decorator
+
+
+# Circular dependencies between core and decorators
+from .core import Command, Group, Argument, Option
diff --git a/python/click/exceptions.py b/python/click/exceptions.py
new file mode 100644
index 0000000..6fa1765
--- /dev/null
+++ b/python/click/exceptions.py
@@ -0,0 +1,235 @@
+from ._compat import PY2, filename_to_ui, get_text_stderr
+from .utils import echo
+
+
+def _join_param_hints(param_hint):
+    if isinstance(param_hint, (tuple, list)):
+        return ' / '.join('"%s"' % x for x in param_hint)
+    return param_hint
+
+
+class ClickException(Exception):
+    """An exception that Click can handle and show to the user."""
+
+    #: The exit code for this exception
+    exit_code = 1
+
+    def __init__(self, message):
+        ctor_msg = message
+        if PY2:
+            if ctor_msg is not None:
+                ctor_msg = ctor_msg.encode('utf-8')
+        Exception.__init__(self, ctor_msg)
+        self.message = message
+
+    def format_message(self):
+        return self.message
+
+    def __str__(self):
+        return self.message
+
+    if PY2:
+        __unicode__ = __str__
+
+        def __str__(self):
+            return self.message.encode('utf-8')
+
+    def show(self, file=None):
+        if file is None:
+            file = get_text_stderr()
+        echo('Error: %s' % self.format_message(), file=file)
+
+
+class UsageError(ClickException):
+    """An internal exception that signals a usage error.  This typically
+    aborts any further handling.
+
+    :param message: the error message to display.
+    :param ctx: optionally the context that caused this error.  Click will
+                fill in the context automatically in some situations.
+    """
+    exit_code = 2
+
+    def __init__(self, message, ctx=None):
+        ClickException.__init__(self, message)
+        self.ctx = ctx
+        self.cmd = self.ctx and self.ctx.command or None
+
+    def show(self, file=None):
+        if file is None:
+            file = get_text_stderr()
+        color = None
+        hint = ''
+        if (self.cmd is not None and
+                self.cmd.get_help_option(self.ctx) is not None):
+            hint = ('Try "%s %s" for help.\n'
+                    % (self.ctx.command_path, self.ctx.help_option_names[0]))
+        if self.ctx is not None:
+            color = self.ctx.color
+            echo(self.ctx.get_usage() + '\n%s' % hint, file=file, color=color)
+        echo('Error: %s' % self.format_message(), file=file, color=color)
+
+
+class BadParameter(UsageError):
+    """An exception that formats out a standardized error message for a
+    bad parameter.  This is useful when thrown from a callback or type as
+    Click will attach contextual information to it (for instance, which
+    parameter it is).
+
+    .. versionadded:: 2.0
+
+    :param param: the parameter object that caused this error.  This can
+                  be left out, and Click will attach this info itself
+                  if possible.
+    :param param_hint: a string that shows up as parameter name.  This
+                       can be used as alternative to `param` in cases
+                       where custom validation should happen.  If it is
+                       a string it's used as such, if it's a list then
+                       each item is quoted and separated.
+    """
+
+    def __init__(self, message, ctx=None, param=None,
+                 param_hint=None):
+        UsageError.__init__(self, message, ctx)
+        self.param = param
+        self.param_hint = param_hint
+
+    def format_message(self):
+        if self.param_hint is not None:
+            param_hint = self.param_hint
+        elif self.param is not None:
+            param_hint = self.param.get_error_hint(self.ctx)
+        else:
+            return 'Invalid value: %s' % self.message
+        param_hint = _join_param_hints(param_hint)
+
+        return 'Invalid value for %s: %s' % (param_hint, self.message)
+
+
+class MissingParameter(BadParameter):
+    """Raised if click required an option or argument but it was not
+    provided when invoking the script.
+
+    .. versionadded:: 4.0
+
+    :param param_type: a string that indicates the type of the parameter.
+                       The default is to inherit the parameter type from
+                       the given `param`.  Valid values are ``'parameter'``,
+                       ``'option'`` or ``'argument'``.
+    """
+
+    def __init__(self, message=None, ctx=None, param=None,
+                 param_hint=None, param_type=None):
+        BadParameter.__init__(self, message, ctx, param, param_hint)
+        self.param_type = param_type
+
+    def format_message(self):
+        if self.param_hint is not None:
+            param_hint = self.param_hint
+        elif self.param is not None:
+            param_hint = self.param.get_error_hint(self.ctx)
+        else:
+            param_hint = None
+        param_hint = _join_param_hints(param_hint)
+
+        param_type = self.param_type
+        if param_type is None and self.param is not None:
+            param_type = self.param.param_type_name
+
+        msg = self.message
+        if self.param is not None:
+            msg_extra = self.param.type.get_missing_message(self.param)
+            if msg_extra:
+                if msg:
+                    msg += '.  ' + msg_extra
+                else:
+                    msg = msg_extra
+
+        return 'Missing %s%s%s%s' % (
+            param_type,
+            param_hint and ' %s' % param_hint or '',
+            msg and '.  ' or '.',
+            msg or '',
+        )
+
+
+class NoSuchOption(UsageError):
+    """Raised if click attempted to handle an option that does not
+    exist.
+
+    .. versionadded:: 4.0
+    """
+
+    def __init__(self, option_name, message=None, possibilities=None,
+                 ctx=None):
+        if message is None:
+            message = 'no such option: %s' % option_name
+        UsageError.__init__(self, message, ctx)
+        self.option_name = option_name
+        self.possibilities = possibilities
+
+    def format_message(self):
+        bits = [self.message]
+        if self.possibilities:
+            if len(self.possibilities) == 1:
+                bits.append('Did you mean %s?' % self.possibilities[0])
+            else:
+                possibilities = sorted(self.possibilities)
+                bits.append('(Possible options: %s)' % ', '.join(possibilities))
+        return '  '.join(bits)
+
+
+class BadOptionUsage(UsageError):
+    """Raised if an option is generally supplied but the use of the option
+    was incorrect.  This is for instance raised if the number of arguments
+    for an option is not correct.
+
+    .. versionadded:: 4.0
+
+    :param option_name: the name of the option being used incorrectly.
+    """
+
+    def __init__(self, option_name, message, ctx=None):
+        UsageError.__init__(self, message, ctx)
+        self.option_name = option_name
+
+
+class BadArgumentUsage(UsageError):
+    """Raised if an argument is generally supplied but the use of the argument
+    was incorrect.  This is for instance raised if the number of values
+    for an argument is not correct.
+
+    .. versionadded:: 6.0
+    """
+
+    def __init__(self, message, ctx=None):
+        UsageError.__init__(self, message, ctx)
+
+
+class FileError(ClickException):
+    """Raised if a file cannot be opened."""
+
+    def __init__(self, filename, hint=None):
+        ui_filename = filename_to_ui(filename)
+        if hint is None:
+            hint = 'unknown error'
+        ClickException.__init__(self, hint)
+        self.ui_filename = ui_filename
+        self.filename = filename
+
+    def format_message(self):
+        return 'Could not open file %s: %s' % (self.ui_filename, self.message)
+
+
+class Abort(RuntimeError):
+    """An internal signalling exception that signals Click to abort."""
+
+
+class Exit(RuntimeError):
+    """An exception that indicates that the application should exit with some
+    status code.
+
+    :param code: the status code to exit with.
+    """
+    def __init__(self, code=0):
+        self.exit_code = code
diff --git a/python/click/formatting.py b/python/click/formatting.py
new file mode 100644
index 0000000..a3d6a4d
--- /dev/null
+++ b/python/click/formatting.py
@@ -0,0 +1,256 @@
+from contextlib import contextmanager
+from .termui import get_terminal_size
+from .parser import split_opt
+from ._compat import term_len
+
+
+# Can force a width.  This is used by the test system
+FORCED_WIDTH = None
+
+
+def measure_table(rows):
+    widths = {}
+    for row in rows:
+        for idx, col in enumerate(row):
+            widths[idx] = max(widths.get(idx, 0), term_len(col))
+    return tuple(y for x, y in sorted(widths.items()))
+
+
+def iter_rows(rows, col_count):
+    for row in rows:
+        row = tuple(row)
+        yield row + ('',) * (col_count - len(row))
+
+
+def wrap_text(text, width=78, initial_indent='', subsequent_indent='',
+              preserve_paragraphs=False):
+    """A helper function that intelligently wraps text.  By default, it
+    assumes that it operates on a single paragraph of text but if the
+    `preserve_paragraphs` parameter is provided it will intelligently
+    handle paragraphs (defined by two empty lines).
+
+    If paragraphs are handled, a paragraph can be prefixed with an empty
+    line containing the ``\\b`` character (``\\x08``) to indicate that
+    no rewrapping should happen in that block.
+
+    :param text: the text that should be rewrapped.
+    :param width: the maximum width for the text.
+    :param initial_indent: the initial indent that should be placed on the
+                           first line as a string.
+    :param subsequent_indent: the indent string that should be placed on
+                              each consecutive line.
+    :param preserve_paragraphs: if this flag is set then the wrapping will
+                                intelligently handle paragraphs.
+    """
+    from ._textwrap import TextWrapper
+    text = text.expandtabs()
+    wrapper = TextWrapper(width, initial_indent=initial_indent,
+                          subsequent_indent=subsequent_indent,
+                          replace_whitespace=False)
+    if not preserve_paragraphs:
+        return wrapper.fill(text)
+
+    p = []
+    buf = []
+    indent = None
+
+    def _flush_par():
+        if not buf:
+            return
+        if buf[0].strip() == '\b':
+            p.append((indent or 0, True, '\n'.join(buf[1:])))
+        else:
+            p.append((indent or 0, False, ' '.join(buf)))
+        del buf[:]
+
+    for line in text.splitlines():
+        if not line:
+            _flush_par()
+            indent = None
+        else:
+            if indent is None:
+                orig_len = term_len(line)
+                line = line.lstrip()
+                indent = orig_len - term_len(line)
+            buf.append(line)
+    _flush_par()
+
+    rv = []
+    for indent, raw, text in p:
+        with wrapper.extra_indent(' ' * indent):
+            if raw:
+                rv.append(wrapper.indent_only(text))
+            else:
+                rv.append(wrapper.fill(text))
+
+    return '\n\n'.join(rv)
+
+
+class HelpFormatter(object):
+    """This class helps with formatting text-based help pages.  It's
+    usually just needed for very special internal cases, but it's also
+    exposed so that developers can write their own fancy outputs.
+
+    At present, it always writes into memory.
+
+    :param indent_increment: the additional increment for each level.
+    :param width: the width for the text.  This defaults to the terminal
+                  width clamped to a maximum of 78.
+    """
+
+    def __init__(self, indent_increment=2, width=None, max_width=None):
+        self.indent_increment = indent_increment
+        if max_width is None:
+            max_width = 80
+        if width is None:
+            width = FORCED_WIDTH
+            if width is None:
+                width = max(min(get_terminal_size()[0], max_width) - 2, 50)
+        self.width = width
+        self.current_indent = 0
+        self.buffer = []
+
+    def write(self, string):
+        """Writes a unicode string into the internal buffer."""
+        self.buffer.append(string)
+
+    def indent(self):
+        """Increases the indentation."""
+        self.current_indent += self.indent_increment
+
+    def dedent(self):
+        """Decreases the indentation."""
+        self.current_indent -= self.indent_increment
+
+    def write_usage(self, prog, args='', prefix='Usage: '):
+        """Writes a usage line into the buffer.
+
+        :param prog: the program name.
+        :param args: whitespace separated list of arguments.
+        :param prefix: the prefix for the first line.
+        """
+        usage_prefix = '%*s%s ' % (self.current_indent, prefix, prog)
+        text_width = self.width - self.current_indent
+
+        if text_width >= (term_len(usage_prefix) + 20):
+            # The arguments will fit to the right of the prefix.
+            indent = ' ' * term_len(usage_prefix)
+            self.write(wrap_text(args, text_width,
+                                 initial_indent=usage_prefix,
+                                 subsequent_indent=indent))
+        else:
+            # The prefix is too long, put the arguments on the next line.
+            self.write(usage_prefix)
+            self.write('\n')
+            indent = ' ' * (max(self.current_indent, term_len(prefix)) + 4)
+            self.write(wrap_text(args, text_width,
+                                 initial_indent=indent,
+                                 subsequent_indent=indent))
+
+        self.write('\n')
+
+    def write_heading(self, heading):
+        """Writes a heading into the buffer."""
+        self.write('%*s%s:\n' % (self.current_indent, '', heading))
+
+    def write_paragraph(self):
+        """Writes a paragraph into the buffer."""
+        if self.buffer:
+            self.write('\n')
+
+    def write_text(self, text):
+        """Writes re-indented text into the buffer.  This rewraps and
+        preserves paragraphs.
+        """
+        text_width = max(self.width - self.current_indent, 11)
+        indent = ' ' * self.current_indent
+        self.write(wrap_text(text, text_width,
+                             initial_indent=indent,
+                             subsequent_indent=indent,
+                             preserve_paragraphs=True))
+        self.write('\n')
+
+    def write_dl(self, rows, col_max=30, col_spacing=2):
+        """Writes a definition list into the buffer.  This is how options
+        and commands are usually formatted.
+
+        :param rows: a list of two item tuples for the terms and values.
+        :param col_max: the maximum width of the first column.
+        :param col_spacing: the number of spaces between the first and
+                            second column.
+        """
+        rows = list(rows)
+        widths = measure_table(rows)
+        if len(widths) != 2:
+            raise TypeError('Expected two columns for definition list')
+
+        first_col = min(widths[0], col_max) + col_spacing
+
+        for first, second in iter_rows(rows, len(widths)):
+            self.write('%*s%s' % (self.current_indent, '', first))
+            if not second:
+                self.write('\n')
+                continue
+            if term_len(first) <= first_col - col_spacing:
+                self.write(' ' * (first_col - term_len(first)))
+            else:
+                self.write('\n')
+                self.write(' ' * (first_col + self.current_indent))
+
+            text_width = max(self.width - first_col - 2, 10)
+            lines = iter(wrap_text(second, text_width).splitlines())
+            if lines:
+                self.write(next(lines) + '\n')
+                for line in lines:
+                    self.write('%*s%s\n' % (
+                        first_col + self.current_indent, '', line))
+            else:
+                self.write('\n')
+
+    @contextmanager
+    def section(self, name):
+        """Helpful context manager that writes a paragraph, a heading,
+        and the indents.
+
+        :param name: the section name that is written as heading.
+        """
+        self.write_paragraph()
+        self.write_heading(name)
+        self.indent()
+        try:
+            yield
+        finally:
+            self.dedent()
+
+    @contextmanager
+    def indentation(self):
+        """A context manager that increases the indentation."""
+        self.indent()
+        try:
+            yield
+        finally:
+            self.dedent()
+
+    def getvalue(self):
+        """Returns the buffer contents."""
+        return ''.join(self.buffer)
+
+
+def join_options(options):
+    """Given a list of option strings this joins them in the most appropriate
+    way and returns them in the form ``(formatted_string,
+    any_prefix_is_slash)`` where the second item in the tuple is a flag that
+    indicates if any of the option prefixes was a slash.
+    """
+    rv = []
+    any_prefix_is_slash = False
+    for opt in options:
+        prefix = split_opt(opt)[0]
+        if prefix == '/':
+            any_prefix_is_slash = True
+        rv.append((len(prefix), opt))
+
+    rv.sort(key=lambda x: x[0])
+
+    rv = ', '.join(x[1] for x in rv)
+    return rv, any_prefix_is_slash
diff --git a/python/click/globals.py b/python/click/globals.py
new file mode 100644
index 0000000..843b594
--- /dev/null
+++ b/python/click/globals.py
@@ -0,0 +1,48 @@
+from threading import local
+
+
+_local = local()
+
+
+def get_current_context(silent=False):
+    """Returns the current click context.  This can be used as a way to
+    access the current context object from anywhere.  This is a more implicit
+    alternative to the :func:`pass_context` decorator.  This function is
+    primarily useful for helpers such as :func:`echo` which might be
+    interested in changing its behavior based on the current context.
+
+    To push the current context, :meth:`Context.scope` can be used.
+
+    .. versionadded:: 5.0
+
+    :param silent: is set to `True` the return value is `None` if no context
+                   is available.  The default behavior is to raise a
+                   :exc:`RuntimeError`.
+    """
+    try:
+        return getattr(_local, 'stack')[-1]
+    except (AttributeError, IndexError):
+        if not silent:
+            raise RuntimeError('There is no active click context.')
+
+
+def push_context(ctx):
+    """Pushes a new context to the current stack."""
+    _local.__dict__.setdefault('stack', []).append(ctx)
+
+
+def pop_context():
+    """Removes the top level from the stack."""
+    _local.stack.pop()
+
+
+def resolve_color_default(color=None):
+    """"Internal helper to get the default value of the color flag.  If a
+    value is passed it's returned unchanged, otherwise it's looked up from
+    the current context.
+    """
+    if color is not None:
+        return color
+    ctx = get_current_context(silent=True)
+    if ctx is not None:
+        return ctx.color
diff --git a/python/click/parser.py b/python/click/parser.py
new file mode 100644
index 0000000..1c3ae9c
--- /dev/null
+++ b/python/click/parser.py
@@ -0,0 +1,427 @@
+# -*- coding: utf-8 -*-
+"""
+click.parser
+~~~~~~~~~~~~
+
+This module started out as largely a copy paste from the stdlib's
+optparse module with the features removed that we do not need from
+optparse because we implement them in Click on a higher level (for
+instance type handling, help formatting and a lot more).
+
+The plan is to remove more and more from here over time.
+
+The reason this is a different module and not optparse from the stdlib
+is that there are differences in 2.x and 3.x about the error messages
+generated and optparse in the stdlib uses gettext for no good reason
+and might cause us issues.
+"""
+
+import re
+from collections import deque
+from .exceptions import UsageError, NoSuchOption, BadOptionUsage, \
+     BadArgumentUsage
+
+
+def _unpack_args(args, nargs_spec):
+    """Given an iterable of arguments and an iterable of nargs specifications,
+    it returns a tuple with all the unpacked arguments at the first index
+    and all remaining arguments as the second.
+
+    The nargs specification is the number of arguments that should be consumed
+    or `-1` to indicate that this position should eat up all the remainders.
+
+    Missing items are filled with `None`.
+    """
+    args = deque(args)
+    nargs_spec = deque(nargs_spec)
+    rv = []
+    spos = None
+
+    def _fetch(c):
+        try:
+            if spos is None:
+                return c.popleft()
+            else:
+                return c.pop()
+        except IndexError:
+            return None
+
+    while nargs_spec:
+        nargs = _fetch(nargs_spec)
+        if nargs == 1:
+            rv.append(_fetch(args))
+        elif nargs > 1:
+            x = [_fetch(args) for _ in range(nargs)]
+            # If we're reversed, we're pulling in the arguments in reverse,
+            # so we need to turn them around.
+            if spos is not None:
+                x.reverse()
+            rv.append(tuple(x))
+        elif nargs < 0:
+            if spos is not None:
+                raise TypeError('Cannot have two nargs < 0')
+            spos = len(rv)
+            rv.append(None)
+
+    # spos is the position of the wildcard (star).  If it's not `None`,
+    # we fill it with the remainder.
+    if spos is not None:
+        rv[spos] = tuple(args)
+        args = []
+        rv[spos + 1:] = reversed(rv[spos + 1:])
+
+    return tuple(rv), list(args)
+
+
+def _error_opt_args(nargs, opt):
+    if nargs == 1:
+        raise BadOptionUsage(opt, '%s option requires an argument' % opt)
+    raise BadOptionUsage(opt, '%s option requires %d arguments' % (opt, nargs))
+
+
+def split_opt(opt):
+    first = opt[:1]
+    if first.isalnum():
+        return '', opt
+    if opt[1:2] == first:
+        return opt[:2], opt[2:]
+    return first, opt[1:]
+
+
+def normalize_opt(opt, ctx):
+    if ctx is None or ctx.token_normalize_func is None:
+        return opt
+    prefix, opt = split_opt(opt)
+    return prefix + ctx.token_normalize_func(opt)
+
+
+def split_arg_string(string):
+    """Given an argument string this attempts to split it into small parts."""
+    rv = []
+    for match in re.finditer(r"('([^'\\]*(?:\\.[^'\\]*)*)'"
+                             r'|"([^"\\]*(?:\\.[^"\\]*)*)"'
+                             r'|\S+)\s*', string, re.S):
+        arg = match.group().strip()
+        if arg[:1] == arg[-1:] and arg[:1] in '"\'':
+            arg = arg[1:-1].encode('ascii', 'backslashreplace') \
+                .decode('unicode-escape')
+        try:
+            arg = type(string)(arg)
+        except UnicodeError:
+            pass
+        rv.append(arg)
+    return rv
+
+
+class Option(object):
+
+    def __init__(self, opts, dest, action=None, nargs=1, const=None, obj=None):
+        self._short_opts = []
+        self._long_opts = []
+        self.prefixes = set()
+
+        for opt in opts:
+            prefix, value = split_opt(opt)
+            if not prefix:
+                raise ValueError('Invalid start character for option (%s)'
+                                 % opt)
+            self.prefixes.add(prefix[0])
+            if len(prefix) == 1 and len(value) == 1:
+                self._short_opts.append(opt)
+            else:
+                self._long_opts.append(opt)
+                self.prefixes.add(prefix)
+
+        if action is None:
+            action = 'store'
+
+        self.dest = dest
+        self.action = action
+        self.nargs = nargs
+        self.const = const
+        self.obj = obj
+
+    @property
+    def takes_value(self):
+        return self.action in ('store', 'append')
+
+    def process(self, value, state):
+        if self.action == 'store':
+            state.opts[self.dest] = value
+        elif self.action == 'store_const':
+            state.opts[self.dest] = self.const
+        elif self.action == 'append':
+            state.opts.setdefault(self.dest, []).append(value)
+        elif self.action == 'append_const':
+            state.opts.setdefault(self.dest, []).append(self.const)
+        elif self.action == 'count':
+            state.opts[self.dest] = state.opts.get(self.dest, 0) + 1
+        else:
+            raise ValueError('unknown action %r' % self.action)
+        state.order.append(self.obj)
+
+
+class Argument(object):
+
+    def __init__(self, dest, nargs=1, obj=None):
+        self.dest = dest
+        self.nargs = nargs
+        self.obj = obj
+
+    def process(self, value, state):
+        if self.nargs > 1:
+            holes = sum(1 for x in value if x is None)
+            if holes == len(value):
+                value = None
+            elif holes != 0:
+                raise BadArgumentUsage('argument %s takes %d values'
+                                       % (self.dest, self.nargs))
+        state.opts[self.dest] = value
+        state.order.append(self.obj)
+
+
+class ParsingState(object):
+
+    def __init__(self, rargs):
+        self.opts = {}
+        self.largs = []
+        self.rargs = rargs
+        self.order = []
+
+
+class OptionParser(object):
+    """The option parser is an internal class that is ultimately used to
+    parse options and arguments.  It's modelled after optparse and brings
+    a similar but vastly simplified API.  It should generally not be used
+    directly as the high level Click classes wrap it for you.
+
+    It's not nearly as extensible as optparse or argparse as it does not
+    implement features that are implemented on a higher level (such as
+    types or defaults).
+
+    :param ctx: optionally the :class:`~click.Context` where this parser
+                should go with.
+    """
+
+    def __init__(self, ctx=None):
+        #: The :class:`~click.Context` for this parser.  This might be
+        #: `None` for some advanced use cases.
+        self.ctx = ctx
+        #: This controls how the parser deals with interspersed arguments.
+        #: If this is set to `False`, the parser will stop on the first
+        #: non-option.  Click uses this to implement nested subcommands
+        #: safely.
+        self.allow_interspersed_args = True
+        #: This tells the parser how to deal with unknown options.  By
+        #: default it will error out (which is sensible), but there is a
+        #: second mode where it will ignore it and continue processing
+        #: after shifting all the unknown options into the resulting args.
+        self.ignore_unknown_options = False
+        if ctx is not None:
+            self.allow_interspersed_args = ctx.allow_interspersed_args
+            self.ignore_unknown_options = ctx.ignore_unknown_options
+        self._short_opt = {}
+        self._long_opt = {}
+        self._opt_prefixes = set(['-', '--'])
+        self._args = []
+
+    def add_option(self, opts, dest, action=None, nargs=1, const=None,
+                   obj=None):
+        """Adds a new option named `dest` to the parser.  The destination
+        is not inferred (unlike with optparse) and needs to be explicitly
+        provided.  Action can be any of ``store``, ``store_const``,
+        ``append``, ``appnd_const`` or ``count``.
+
+        The `obj` can be used to identify the option in the order list
+        that is returned from the parser.
+        """
+        if obj is None:
+            obj = dest
+        opts = [normalize_opt(opt, self.ctx) for opt in opts]
+        option = Option(opts, dest, action=action, nargs=nargs,
+                        const=const, obj=obj)
+        self._opt_prefixes.update(option.prefixes)
+        for opt in option._short_opts:
+            self._short_opt[opt] = option
+        for opt in option._long_opts:
+            self._long_opt[opt] = option
+
+    def add_argument(self, dest, nargs=1, obj=None):
+        """Adds a positional argument named `dest` to the parser.
+
+        The `obj` can be used to identify the option in the order list
+        that is returned from the parser.
+        """
+        if obj is None:
+            obj = dest
+        self._args.append(Argument(dest=dest, nargs=nargs, obj=obj))
+
+    def parse_args(self, args):
+        """Parses positional arguments and returns ``(values, args, order)``
+        for the parsed options and arguments as well as the leftover
+        arguments if there are any.  The order is a list of objects as they
+        appear on the command line.  If arguments appear multiple times they
+        will be memorized multiple times as well.
+        """
+        state = ParsingState(args)
+        try:
+            self._process_args_for_options(state)
+            self._process_args_for_args(state)
+        except UsageError:
+            if self.ctx is None or not self.ctx.resilient_parsing:
+                raise
+        return state.opts, state.largs, state.order
+
+    def _process_args_for_args(self, state):
+        pargs, args = _unpack_args(state.largs + state.rargs,
+                                   [x.nargs for x in self._args])
+
+        for idx, arg in enumerate(self._args):
+            arg.process(pargs[idx], state)
+
+        state.largs = args
+        state.rargs = []
+
+    def _process_args_for_options(self, state):
+        while state.rargs:
+            arg = state.rargs.pop(0)
+            arglen = len(arg)
+            # Double dashes always handled explicitly regardless of what
+            # prefixes are valid.
+            if arg == '--':
+                return
+            elif arg[:1] in self._opt_prefixes and arglen > 1:
+                self._process_opts(arg, state)
+            elif self.allow_interspersed_args:
+                state.largs.append(arg)
+            else:
+                state.rargs.insert(0, arg)
+                return
+
+        # Say this is the original argument list:
+        # [arg0, arg1, ..., arg(i-1), arg(i), arg(i+1), ..., arg(N-1)]
+        #                            ^
+        # (we are about to process arg(i)).
+        #
+        # Then rargs is [arg(i), ..., arg(N-1)] and largs is a *subset* of
+        # [arg0, ..., arg(i-1)] (any options and their arguments will have
+        # been removed from largs).
+        #
+        # The while loop will usually consume 1 or more arguments per pass.
+        # If it consumes 1 (eg. arg is an option that takes no arguments),
+        # then after _process_arg() is done the situation is:
+        #
+        #   largs = subset of [arg0, ..., arg(i)]
+        #   rargs = [arg(i+1), ..., arg(N-1)]
+        #
+        # If allow_interspersed_args is false, largs will always be
+        # *empty* -- still a subset of [arg0, ..., arg(i-1)], but
+        # not a very interesting subset!
+
+    def _match_long_opt(self, opt, explicit_value, state):
+        if opt not in self._long_opt:
+            possibilities = [word for word in self._long_opt
+                             if word.startswith(opt)]
+            raise NoSuchOption(opt, possibilities=possibilities, ctx=self.ctx)
+
+        option = self._long_opt[opt]
+        if option.takes_value:
+            # At this point it's safe to modify rargs by injecting the
+            # explicit value, because no exception is raised in this
+            # branch.  This means that the inserted value will be fully
+            # consumed.
+            if explicit_value is not None:
+                state.rargs.insert(0, explicit_value)
+
+            nargs = option.nargs
+            if len(state.rargs) < nargs:
+                _error_opt_args(nargs, opt)
+            elif nargs == 1:
+                value = state.rargs.pop(0)
+            else:
+                value = tuple(state.rargs[:nargs])
+                del state.rargs[:nargs]
+
+        elif explicit_value is not None:
+            raise BadOptionUsage(opt, '%s option does not take a value' % opt)
+
+        else:
+            value = None
+
+        option.process(value, state)
+
+    def _match_short_opt(self, arg, state):
+        stop = False
+        i = 1
+        prefix = arg[0]
+        unknown_options = []
+
+        for ch in arg[1:]:
+            opt = normalize_opt(prefix + ch, self.ctx)
+            option = self._short_opt.get(opt)
+            i += 1
+
+            if not option:
+                if self.ignore_unknown_options:
+                    unknown_options.append(ch)
+                    continue
+                raise NoSuchOption(opt, ctx=self.ctx)
+            if option.takes_value:
+                # Any characters left in arg?  Pretend they're the
+                # next arg, and stop consuming characters of arg.
+                if i < len(arg):
+                    state.rargs.insert(0, arg[i:])
+                    stop = True
+
+                nargs = option.nargs
+                if len(state.rargs) < nargs:
+                    _error_opt_args(nargs, opt)
+                elif nargs == 1:
+                    value = state.rargs.pop(0)
+                else:
+                    value = tuple(state.rargs[:nargs])
+                    del state.rargs[:nargs]
+
+            else:
+                value = None
+
+            option.process(value, state)
+
+            if stop:
+                break
+
+        # If we got any unknown options we re-combinate the string of the
+        # remaining options and re-attach the prefix, then report that
+        # to the state as new larg.  This way there is basic combinatorics
+        # that can be achieved while still ignoring unknown arguments.
+        if self.ignore_unknown_options and unknown_options:
+            state.largs.append(prefix + ''.join(unknown_options))
+
+    def _process_opts(self, arg, state):
+        explicit_value = None
+        # Long option handling happens in two parts.  The first part is
+        # supporting explicitly attached values.  In any case, we will try
+        # to long match the option first.
+        if '=' in arg:
+            long_opt, explicit_value = arg.split('=', 1)
+        else:
+            long_opt = arg
+        norm_long_opt = normalize_opt(long_opt, self.ctx)
+
+        # At this point we will match the (assumed) long option through
+        # the long option matching code.  Note that this allows options
+        # like "-foo" to be matched as long options.
+        try:
+            self._match_long_opt(norm_long_opt, explicit_value, state)
+        except NoSuchOption:
+            # At this point the long option matching failed, and we need
+            # to try with short options.  However there is a special rule
+            # which says, that if we have a two character options prefix
+            # (applies to "--foo" for instance), we do not dispatch to the
+            # short option code and will instead raise the no option
+            # error.
+            if arg[:2] not in self._opt_prefixes:
+                return self._match_short_opt(arg, state)
+            if not self.ignore_unknown_options:
+                raise
+            state.largs.append(arg)
diff --git a/python/click/termui.py b/python/click/termui.py
new file mode 100644
index 0000000..bf9a3aa
--- /dev/null
+++ b/python/click/termui.py
@@ -0,0 +1,606 @@
+import os
+import sys
+import struct
+import inspect
+import itertools
+
+from ._compat import raw_input, text_type, string_types, \
+     isatty, strip_ansi, get_winterm_size, DEFAULT_COLUMNS, WIN
+from .utils import echo
+from .exceptions import Abort, UsageError
+from .types import convert_type, Choice, Path
+from .globals import resolve_color_default
+
+
+# The prompt functions to use.  The doc tools currently override these
+# functions to customize how they work.
+visible_prompt_func = raw_input
+
+_ansi_colors = {
+    'black': 30,
+    'red': 31,
+    'green': 32,
+    'yellow': 33,
+    'blue': 34,
+    'magenta': 35,
+    'cyan': 36,
+    'white': 37,
+    'reset': 39,
+    'bright_black': 90,
+    'bright_red': 91,
+    'bright_green': 92,
+    'bright_yellow': 93,
+    'bright_blue': 94,
+    'bright_magenta': 95,
+    'bright_cyan': 96,
+    'bright_white': 97,
+}
+_ansi_reset_all = '\033[0m'
+
+
+def hidden_prompt_func(prompt):
+    import getpass
+    return getpass.getpass(prompt)
+
+
+def _build_prompt(text, suffix, show_default=False, default=None, show_choices=True, type=None):
+    prompt = text
+    if type is not None and show_choices and isinstance(type, Choice):
+        prompt += ' (' + ", ".join(map(str, type.choices)) + ')'
+    if default is not None and show_default:
+        prompt = '%s [%s]' % (prompt, default)
+    return prompt + suffix
+
+
+def prompt(text, default=None, hide_input=False, confirmation_prompt=False,
+           type=None, value_proc=None, prompt_suffix=': ', show_default=True,
+           err=False, show_choices=True):
+    """Prompts a user for input.  This is a convenience function that can
+    be used to prompt a user for input later.
+
+    If the user aborts the input by sending a interrupt signal, this
+    function will catch it and raise a :exc:`Abort` exception.
+
+    .. versionadded:: 7.0
+       Added the show_choices parameter.
+
+    .. versionadded:: 6.0
+       Added unicode support for cmd.exe on Windows.
+
+    .. versionadded:: 4.0
+       Added the `err` parameter.
+
+    :param text: the text to show for the prompt.
+    :param default: the default value to use if no input happens.  If this
+                    is not given it will prompt until it's aborted.
+    :param hide_input: if this is set to true then the input value will
+                       be hidden.
+    :param confirmation_prompt: asks for confirmation for the value.
+    :param type: the type to use to check the value against.
+    :param value_proc: if this parameter is provided it's a function that
+                       is invoked instead of the type conversion to
+                       convert a value.
+    :param prompt_suffix: a suffix that should be added to the prompt.
+    :param show_default: shows or hides the default value in the prompt.
+    :param err: if set to true the file defaults to ``stderr`` instead of
+                ``stdout``, the same as with echo.
+    :param show_choices: Show or hide choices if the passed type is a Choice.
+                         For example if type is a Choice of either day or week,
+                         show_choices is true and text is "Group by" then the
+                         prompt will be "Group by (day, week): ".
+    """
+    result = None
+
+    def prompt_func(text):
+        f = hide_input and hidden_prompt_func or visible_prompt_func
+        try:
+            # Write the prompt separately so that we get nice
+            # coloring through colorama on Windows
+            echo(text, nl=False, err=err)
+            return f('')
+        except (KeyboardInterrupt, EOFError):
+            # getpass doesn't print a newline if the user aborts input with ^C.
+            # Allegedly this behavior is inherited from getpass(3).
+            # A doc bug has been filed at https://bugs.python.org/issue24711
+            if hide_input:
+                echo(None, err=err)
+            raise Abort()
+
+    if value_proc is None:
+        value_proc = convert_type(type, default)
+
+    prompt = _build_prompt(text, prompt_suffix, show_default, default, show_choices, type)
+
+    while 1:
+        while 1:
+            value = prompt_func(prompt)
+            if value:
+                break
+            elif default is not None:
+                if isinstance(value_proc, Path):
+                    # validate Path default value(exists, dir_okay etc.)
+                    value = default
+                    break
+                return default
+        try:
+            result = value_proc(value)
+        except UsageError as e:
+            echo('Error: %s' % e.message, err=err)
+            continue
+        if not confirmation_prompt:
+            return result
+        while 1:
+            value2 = prompt_func('Repeat for confirmation: ')
+            if value2:
+                break
+        if value == value2:
+            return result
+        echo('Error: the two entered values do not match', err=err)
+
+
+def confirm(text, default=False, abort=False, prompt_suffix=': ',
+            show_default=True, err=False):
+    """Prompts for confirmation (yes/no question).
+
+    If the user aborts the input by sending a interrupt signal this
+    function will catch it and raise a :exc:`Abort` exception.
+
+    .. versionadded:: 4.0
+       Added the `err` parameter.
+
+    :param text: the question to ask.
+    :param default: the default for the prompt.
+    :param abort: if this is set to `True` a negative answer aborts the
+                  exception by raising :exc:`Abort`.
+    :param prompt_suffix: a suffix that should be added to the prompt.
+    :param show_default: shows or hides the default value in the prompt.
+    :param err: if set to true the file defaults to ``stderr`` instead of
+                ``stdout``, the same as with echo.
+    """
+    prompt = _build_prompt(text, prompt_suffix, show_default,
+                           default and 'Y/n' or 'y/N')
+    while 1:
+        try:
+            # Write the prompt separately so that we get nice
+            # coloring through colorama on Windows
+            echo(prompt, nl=False, err=err)
+            value = visible_prompt_func('').lower().strip()
+        except (KeyboardInterrupt, EOFError):
+            raise Abort()
+        if value in ('y', 'yes'):
+            rv = True
+        elif value in ('n', 'no'):
+            rv = False
+        elif value == '':
+            rv = default
+        else:
+            echo('Error: invalid input', err=err)
+            continue
+        break
+    if abort and not rv:
+        raise Abort()
+    return rv
+
+
+def get_terminal_size():
+    """Returns the current size of the terminal as tuple in the form
+    ``(width, height)`` in columns and rows.
+    """
+    # If shutil has get_terminal_size() (Python 3.3 and later) use that
+    if sys.version_info >= (3, 3):
+        import shutil
+        shutil_get_terminal_size = getattr(shutil, 'get_terminal_size', None)
+        if shutil_get_terminal_size:
+            sz = shutil_get_terminal_size()
+            return sz.columns, sz.lines
+
+    # We provide a sensible default for get_winterm_size() when being invoked
+    # inside a subprocess. Without this, it would not provide a useful input.
+    if get_winterm_size is not None:
+        size = get_winterm_size()
+        if size == (0, 0):
+            return (79, 24)
+        else:
+            return size
+
+    def ioctl_gwinsz(fd):
+        try:
+            import fcntl
+            import termios
+            cr = struct.unpack(
+                'hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, '1234'))
+        except Exception:
+            return
+        return cr
+
+    cr = ioctl_gwinsz(0) or ioctl_gwinsz(1) or ioctl_gwinsz(2)
+    if not cr:
+        try:
+            fd = os.open(os.ctermid(), os.O_RDONLY)
+            try:
+                cr = ioctl_gwinsz(fd)
+            finally:
+                os.close(fd)
+        except Exception:
+            pass
+    if not cr or not cr[0] or not cr[1]:
+        cr = (os.environ.get('LINES', 25),
+              os.environ.get('COLUMNS', DEFAULT_COLUMNS))
+    return int(cr[1]), int(cr[0])
+
+
+def echo_via_pager(text_or_generator, color=None):
+    """This function takes a text and shows it via an environment specific
+    pager on stdout.
+
+    .. versionchanged:: 3.0
+       Added the `color` flag.
+
+    :param text_or_generator: the text to page, or alternatively, a
+                              generator emitting the text to page.
+    :param color: controls if the pager supports ANSI colors or not.  The
+                  default is autodetection.
+    """
+    color = resolve_color_default(color)
+
+    if inspect.isgeneratorfunction(text_or_generator):
+        i = text_or_generator()
+    elif isinstance(text_or_generator, string_types):
+        i = [text_or_generator]
+    else:
+        i = iter(text_or_generator)
+
+    # convert every element of i to a text type if necessary
+    text_generator = (el if isinstance(el, string_types) else text_type(el)
+                      for el in i)
+
+    from ._termui_impl import pager
+    return pager(itertools.chain(text_generator, "\n"), color)
+
+
+def progressbar(iterable=None, length=None, label=None, show_eta=True,
+                show_percent=None, show_pos=False,
+                item_show_func=None, fill_char='#', empty_char='-',
+                bar_template='%(label)s  [%(bar)s]  %(info)s',
+                info_sep='  ', width=36, file=None, color=None):
+    """This function creates an iterable context manager that can be used
+    to iterate over something while showing a progress bar.  It will
+    either iterate over the `iterable` or `length` items (that are counted
+    up).  While iteration happens, this function will print a rendered
+    progress bar to the given `file` (defaults to stdout) and will attempt
+    to calculate remaining time and more.  By default, this progress bar
+    will not be rendered if the file is not a terminal.
+
+    The context manager creates the progress bar.  When the context
+    manager is entered the progress bar is already displayed.  With every
+    iteration over the progress bar, the iterable passed to the bar is
+    advanced and the bar is updated.  When the context manager exits,
+    a newline is printed and the progress bar is finalized on screen.
+
+    No printing must happen or the progress bar will be unintentionally
+    destroyed.
+
+    Example usage::
+
+        with progressbar(items) as bar:
+            for item in bar:
+                do_something_with(item)
+
+    Alternatively, if no iterable is specified, one can manually update the
+    progress bar through the `update()` method instead of directly
+    iterating over the progress bar.  The update method accepts the number
+    of steps to increment the bar with::
+
+        with progressbar(length=chunks.total_bytes) as bar:
+            for chunk in chunks:
+                process_chunk(chunk)
+                bar.update(chunks.bytes)
+
+    .. versionadded:: 2.0
+
+    .. versionadded:: 4.0
+       Added the `color` parameter.  Added a `update` method to the
+       progressbar object.
+
+    :param iterable: an iterable to iterate over.  If not provided the length
+                     is required.
+    :param length: the number of items to iterate over.  By default the
+                   progressbar will attempt to ask the iterator about its
+                   length, which might or might not work.  If an iterable is
+                   also provided this parameter can be used to override the
+                   length.  If an iterable is not provided the progress bar
+                   will iterate over a range of that length.
+    :param label: the label to show next to the progress bar.
+    :param show_eta: enables or disables the estimated time display.  This is
+                     automatically disabled if the length cannot be
+                     determined.
+    :param show_percent: enables or disables the percentage display.  The
+                         default is `True` if the iterable has a length or
+                         `False` if not.
+    :param show_pos: enables or disables the absolute position display.  The
+                     default is `False`.
+    :param item_show_func: a function called with the current item which
+                           can return a string to show the current item
+                           next to the progress bar.  Note that the current
+                           item can be `None`!
+    :param fill_char: the character to use to show the filled part of the
+                      progress bar.
+    :param empty_char: the character to use to show the non-filled part of
+                       the progress bar.
+    :param bar_template: the format string to use as template for the bar.
+                         The parameters in it are ``label`` for the label,
+                         ``bar`` for the progress bar and ``info`` for the
+                         info section.
+    :param info_sep: the separator between multiple info items (eta etc.)
+    :param width: the width of the progress bar in characters, 0 means full
+                  terminal width
+    :param file: the file to write to.  If this is not a terminal then
+                 only the label is printed.
+    :param color: controls if the terminal supports ANSI colors or not.  The
+                  default is autodetection.  This is only needed if ANSI
+                  codes are included anywhere in the progress bar output
+                  which is not the case by default.
+    """
+    from ._termui_impl import ProgressBar
+    color = resolve_color_default(color)
+    return ProgressBar(iterable=iterable, length=length, show_eta=show_eta,
+                       show_percent=show_percent, show_pos=show_pos,
+                       item_show_func=item_show_func, fill_char=fill_char,
+                       empty_char=empty_char, bar_template=bar_template,
+                       info_sep=info_sep, file=file, label=label,
+                       width=width, color=color)
+
+
+def clear():
+    """Clears the terminal screen.  This will have the effect of clearing
+    the whole visible space of the terminal and moving the cursor to the
+    top left.  This does not do anything if not connected to a terminal.
+
+    .. versionadded:: 2.0
+    """
+    if not isatty(sys.stdout):
+        return
+    # If we're on Windows and we don't have colorama available, then we
+    # clear the screen by shelling out.  Otherwise we can use an escape
+    # sequence.
+    if WIN:
+        os.system('cls')
+    else:
+        sys.stdout.write('\033[2J\033[1;1H')
+
+
+def style(text, fg=None, bg=None, bold=None, dim=None, underline=None,
+          blink=None, reverse=None, reset=True):
+    """Styles a text with ANSI styles and returns the new string.  By
+    default the styling is self contained which means that at the end
+    of the string a reset code is issued.  This can be prevented by
+    passing ``reset=False``.
+
+    Examples::
+
+        click.echo(click.style('Hello World!', fg='green'))
+        click.echo(click.style('ATTENTION!', blink=True))
+        click.echo(click.style('Some things', reverse=True, fg='cyan'))
+
+    Supported color names:
+
+    * ``black`` (might be a gray)
+    * ``red``
+    * ``green``
+    * ``yellow`` (might be an orange)
+    * ``blue``
+    * ``magenta``
+    * ``cyan``
+    * ``white`` (might be light gray)
+    * ``bright_black``
+    * ``bright_red``
+    * ``bright_green``
+    * ``bright_yellow``
+    * ``bright_blue``
+    * ``bright_magenta``
+    * ``bright_cyan``
+    * ``bright_white``
+    * ``reset`` (reset the color code only)
+
+    .. versionadded:: 2.0
+
+    .. versionadded:: 7.0
+       Added support for bright colors.
+
+    :param text: the string to style with ansi codes.
+    :param fg: if provided this will become the foreground color.
+    :param bg: if provided this will become the background color.
+    :param bold: if provided this will enable or disable bold mode.
+    :param dim: if provided this will enable or disable dim mode.  This is
+                badly supported.
+    :param underline: if provided this will enable or disable underline.
+    :param blink: if provided this will enable or disable blinking.
+    :param reverse: if provided this will enable or disable inverse
+                    rendering (foreground becomes background and the
+                    other way round).
+    :param reset: by default a reset-all code is added at the end of the
+                  string which means that styles do not carry over.  This
+                  can be disabled to compose styles.
+    """
+    bits = []
+    if fg:
+        try:
+            bits.append('\033[%dm' % (_ansi_colors[fg]))
+        except KeyError:
+            raise TypeError('Unknown color %r' % fg)
+    if bg:
+        try:
+            bits.append('\033[%dm' % (_ansi_colors[bg] + 10))
+        except KeyError:
+            raise TypeError('Unknown color %r' % bg)
+    if bold is not None:
+        bits.append('\033[%dm' % (1 if bold else 22))
+    if dim is not None:
+        bits.append('\033[%dm' % (2 if dim else 22))
+    if underline is not None:
+        bits.append('\033[%dm' % (4 if underline else 24))
+    if blink is not None:
+        bits.append('\033[%dm' % (5 if blink else 25))
+    if reverse is not None:
+        bits.append('\033[%dm' % (7 if reverse else 27))
+    bits.append(text)
+    if reset:
+        bits.append(_ansi_reset_all)
+    return ''.join(bits)
+
+
+def unstyle(text):
+    """Removes ANSI styling information from a string.  Usually it's not
+    necessary to use this function as Click's echo function will
+    automatically remove styling if necessary.
+
+    .. versionadded:: 2.0
+
+    :param text: the text to remove style information from.
+    """
+    return strip_ansi(text)
+
+
+def secho(message=None, file=None, nl=True, err=False, color=None, **styles):
+    """This function combines :func:`echo` and :func:`style` into one
+    call.  As such the following two calls are the same::
+
+        click.secho('Hello World!', fg='green')
+        click.echo(click.style('Hello World!', fg='green'))
+
+    All keyword arguments are forwarded to the underlying functions
+    depending on which one they go with.
+
+    .. versionadded:: 2.0
+    """
+    if message is not None:
+        message = style(message, **styles)
+    return echo(message, file=file, nl=nl, err=err, color=color)
+
+
+def edit(text=None, editor=None, env=None, require_save=True,
+         extension='.txt', filename=None):
+    r"""Edits the given text in the defined editor.  If an editor is given
+    (should be the full path to the executable but the regular operating
+    system search path is used for finding the executable) it overrides
+    the detected editor.  Optionally, some environment variables can be
+    used.  If the editor is closed without changes, `None` is returned.  In
+    case a file is edited directly the return value is always `None` and
+    `require_save` and `extension` are ignored.
+
+    If the editor cannot be opened a :exc:`UsageError` is raised.
+
+    Note for Windows: to simplify cross-platform usage, the newlines are
+    automatically converted from POSIX to Windows and vice versa.  As such,
+    the message here will have ``\n`` as newline markers.
+
+    :param text: the text to edit.
+    :param editor: optionally the editor to use.  Defaults to automatic
+                   detection.
+    :param env: environment variables to forward to the editor.
+    :param require_save: if this is true, then not saving in the editor
+                         will make the return value become `None`.
+    :param extension: the extension to tell the editor about.  This defaults
+                      to `.txt` but changing this might change syntax
+                      highlighting.
+    :param filename: if provided it will edit this file instead of the
+                     provided text contents.  It will not use a temporary
+                     file as an indirection in that case.
+    """
+    from ._termui_impl import Editor
+    editor = Editor(editor=editor, env=env, require_save=require_save,
+                    extension=extension)
+    if filename is None:
+        return editor.edit(text)
+    editor.edit_file(filename)
+
+
+def launch(url, wait=False, locate=False):
+    """This function launches the given URL (or filename) in the default
+    viewer application for this file type.  If this is an executable, it
+    might launch the executable in a new session.  The return value is
+    the exit code of the launched application.  Usually, ``0`` indicates
+    success.
+
+    Examples::
+
+        click.launch('https://click.palletsprojects.com/')
+        click.launch('/my/downloaded/file', locate=True)
+
+    .. versionadded:: 2.0
+
+    :param url: URL or filename of the thing to launch.
+    :param wait: waits for the program to stop.
+    :param locate: if this is set to `True` then instead of launching the
+                   application associated with the URL it will attempt to
+                   launch a file manager with the file located.  This
+                   might have weird effects if the URL does not point to
+                   the filesystem.
+    """
+    from ._termui_impl import open_url
+    return open_url(url, wait=wait, locate=locate)
+
+
+# If this is provided, getchar() calls into this instead.  This is used
+# for unittesting purposes.
+_getchar = None
+
+
+def getchar(echo=False):
+    """Fetches a single character from the terminal and returns it.  This
+    will always return a unicode character and under certain rare
+    circumstances this might return more than one character.  The
+    situations which more than one character is returned is when for
+    whatever reason multiple characters end up in the terminal buffer or
+    standard input was not actually a terminal.
+
+    Note that this will always read from the terminal, even if something
+    is piped into the standard input.
+
+    Note for Windows: in rare cases when typing non-ASCII characters, this
+    function might wait for a second character and then return both at once.
+    This is because certain Unicode characters look like special-key markers.
+
+    .. versionadded:: 2.0
+
+    :param echo: if set to `True`, the character read will also show up on
+                 the terminal.  The default is to not show it.
+    """
+    f = _getchar
+    if f is None:
+        from ._termui_impl import getchar as f
+    return f(echo)
+
+
+def raw_terminal():
+    from ._termui_impl import raw_terminal as f
+    return f()
+
+
+def pause(info='Press any key to continue ...', err=False):
+    """This command stops execution and waits for the user to press any
+    key to continue.  This is similar to the Windows batch "pause"
+    command.  If the program is not run through a terminal, this command
+    will instead do nothing.
+
+    .. versionadded:: 2.0
+
+    .. versionadded:: 4.0
+       Added the `err` parameter.
+
+    :param info: the info string to print before pausing.
+    :param err: if set to message goes to ``stderr`` instead of
+                ``stdout``, the same as with echo.
+    """
+    if not isatty(sys.stdin) or not isatty(sys.stdout):
+        return
+    try:
+        if info:
+            echo(info, nl=False, err=err)
+        try:
+            getchar()
+        except (KeyboardInterrupt, EOFError):
+            pass
+    finally:
+        if info:
+            echo(err=err)
diff --git a/python/click/testing.py b/python/click/testing.py
new file mode 100644
index 0000000..1b2924e
--- /dev/null
+++ b/python/click/testing.py
@@ -0,0 +1,374 @@
+import os
+import sys
+import shutil
+import tempfile
+import contextlib
+import shlex
+
+from ._compat import iteritems, PY2, string_types
+
+
+# If someone wants to vendor click, we want to ensure the
+# correct package is discovered.  Ideally we could use a
+# relative import here but unfortunately Python does not
+# support that.
+clickpkg = sys.modules[__name__.rsplit('.', 1)[0]]
+
+
+if PY2:
+    from cStringIO import StringIO
+else:
+    import io
+    from ._compat import _find_binary_reader
+
+
+class EchoingStdin(object):
+
+    def __init__(self, input, output):
+        self._input = input
+        self._output = output
+
+    def __getattr__(self, x):
+        return getattr(self._input, x)
+
+    def _echo(self, rv):
+        self._output.write(rv)
+        return rv
+
+    def read(self, n=-1):
+        return self._echo(self._input.read(n))
+
+    def readline(self, n=-1):
+        return self._echo(self._input.readline(n))
+
+    def readlines(self):
+        return [self._echo(x) for x in self._input.readlines()]
+
+    def __iter__(self):
+        return iter(self._echo(x) for x in self._input)
+
+    def __repr__(self):
+        return repr(self._input)
+
+
+def make_input_stream(input, charset):
+    # Is already an input stream.
+    if hasattr(input, 'read'):
+        if PY2:
+            return input
+        rv = _find_binary_reader(input)
+        if rv is not None:
+            return rv
+        raise TypeError('Could not find binary reader for input stream.')
+
+    if input is None:
+        input = b''
+    elif not isinstance(input, bytes):
+        input = input.encode(charset)
+    if PY2:
+        return StringIO(input)
+    return io.BytesIO(input)
+
+
+class Result(object):
+    """Holds the captured result of an invoked CLI script."""
+
+    def __init__(self, runner, stdout_bytes, stderr_bytes, exit_code,
+                 exception, exc_info=None):
+        #: The runner that created the result
+        self.runner = runner
+        #: The standard output as bytes.
+        self.stdout_bytes = stdout_bytes
+        #: The standard error as bytes, or False(y) if not available
+        self.stderr_bytes = stderr_bytes
+        #: The exit code as integer.
+        self.exit_code = exit_code
+        #: The exception that happened if one did.
+        self.exception = exception
+        #: The traceback
+        self.exc_info = exc_info
+
+    @property
+    def output(self):
+        """The (standard) output as unicode string."""
+        return self.stdout
+
+    @property
+    def stdout(self):
+        """The standard output as unicode string."""
+        return self.stdout_bytes.decode(self.runner.charset, 'replace') \
+            .replace('\r\n', '\n')
+
+    @property
+    def stderr(self):
+        """The standard error as unicode string."""
+        if not self.stderr_bytes:
+            raise ValueError("stderr not separately captured")
+        return self.stderr_bytes.decode(self.runner.charset, 'replace') \
+            .replace('\r\n', '\n')
+
+
+    def __repr__(self):
+        return '<%s %s>' % (
+            type(self).__name__,
+            self.exception and repr(self.exception) or 'okay',
+        )
+
+
+class CliRunner(object):
+    """The CLI runner provides functionality to invoke a Click command line
+    script for unittesting purposes in a isolated environment.  This only
+    works in single-threaded systems without any concurrency as it changes the
+    global interpreter state.
+
+    :param charset: the character set for the input and output data.  This is
+                    UTF-8 by default and should not be changed currently as
+                    the reporting to Click only works in Python 2 properly.
+    :param env: a dictionary with environment variables for overriding.
+    :param echo_stdin: if this is set to `True`, then reading from stdin writes
+                       to stdout.  This is useful for showing examples in
+                       some circumstances.  Note that regular prompts
+                       will automatically echo the input.
+    :param mix_stderr: if this is set to `False`, then stdout and stderr are
+                       preserved as independent streams.  This is useful for
+                       Unix-philosophy apps that have predictable stdout and
+                       noisy stderr, such that each may be measured
+                       independently
+    """
+
+    def __init__(self, charset=None, env=None, echo_stdin=False,
+                 mix_stderr=True):
+        if charset is None:
+            charset = 'utf-8'
+        self.charset = charset
+        self.env = env or {}
+        self.echo_stdin = echo_stdin
+        self.mix_stderr = mix_stderr
+
+    def get_default_prog_name(self, cli):
+        """Given a command object it will return the default program name
+        for it.  The default is the `name` attribute or ``"root"`` if not
+        set.
+        """
+        return cli.name or 'root'
+
+    def make_env(self, overrides=None):
+        """Returns the environment overrides for invoking a script."""
+        rv = dict(self.env)
+        if overrides:
+            rv.update(overrides)
+        return rv
+
+    @contextlib.contextmanager
+    def isolation(self, input=None, env=None, color=False):
+        """A context manager that sets up the isolation for invoking of a
+        command line tool.  This sets up stdin with the given input data
+        and `os.environ` with the overrides from the given dictionary.
+        This also rebinds some internals in Click to be mocked (like the
+        prompt functionality).
+
+        This is automatically done in the :meth:`invoke` method.
+
+        .. versionadded:: 4.0
+           The ``color`` parameter was added.
+
+        :param input: the input stream to put into sys.stdin.
+        :param env: the environment overrides as dictionary.
+        :param color: whether the output should contain color codes. The
+                      application can still override this explicitly.
+        """
+        input = make_input_stream(input, self.charset)
+
+        old_stdin = sys.stdin
+        old_stdout = sys.stdout
+        old_stderr = sys.stderr
+        old_forced_width = clickpkg.formatting.FORCED_WIDTH
+        clickpkg.formatting.FORCED_WIDTH = 80
+
+        env = self.make_env(env)
+
+        if PY2:
+            bytes_output = StringIO()
+            if self.echo_stdin:
+                input = EchoingStdin(input, bytes_output)
+            sys.stdout = bytes_output
+            if not self.mix_stderr:
+                bytes_error = StringIO()
+                sys.stderr = bytes_error
+        else:
+            bytes_output = io.BytesIO()
+            if self.echo_stdin:
+                input = EchoingStdin(input, bytes_output)
+            input = io.TextIOWrapper(input, encoding=self.charset)
+            sys.stdout = io.TextIOWrapper(
+                bytes_output, encoding=self.charset)
+            if not self.mix_stderr:
+                bytes_error = io.BytesIO()
+                sys.stderr = io.TextIOWrapper(
+                    bytes_error, encoding=self.charset)
+
+        if self.mix_stderr:
+            sys.stderr = sys.stdout
+
+        sys.stdin = input
+
+        def visible_input(prompt=None):
+            sys.stdout.write(prompt or '')
+            val = input.readline().rstrip('\r\n')
+            sys.stdout.write(val + '\n')
+            sys.stdout.flush()
+            return val
+
+        def hidden_input(prompt=None):
+            sys.stdout.write((prompt or '') + '\n')
+            sys.stdout.flush()
+            return input.readline().rstrip('\r\n')
+
+        def _getchar(echo):
+            char = sys.stdin.read(1)
+            if echo:
+                sys.stdout.write(char)
+                sys.stdout.flush()
+            return char
+
+        default_color = color
+
+        def should_strip_ansi(stream=None, color=None):
+            if color is None:
+                return not default_color
+            return not color
+
+        old_visible_prompt_func = clickpkg.termui.visible_prompt_func
+        old_hidden_prompt_func = clickpkg.termui.hidden_prompt_func
+        old__getchar_func = clickpkg.termui._getchar
+        old_should_strip_ansi = clickpkg.utils.should_strip_ansi
+        clickpkg.termui.visible_prompt_func = visible_input
+        clickpkg.termui.hidden_prompt_func = hidden_input
+        clickpkg.termui._getchar = _getchar
+        clickpkg.utils.should_strip_ansi = should_strip_ansi
+
+        old_env = {}
+        try:
+            for key, value in iteritems(env):
+                old_env[key] = os.environ.get(key)
+                if value is None:
+                    try:
+                        del os.environ[key]
+                    except Exception:
+                        pass
+                else:
+                    os.environ[key] = value
+            yield (bytes_output, not self.mix_stderr and bytes_error)
+        finally:
+            for key, value in iteritems(old_env):
+                if value is None:
+                    try:
+                        del os.environ[key]
+                    except Exception:
+                        pass
+                else:
+                    os.environ[key] = value
+            sys.stdout = old_stdout
+            sys.stderr = old_stderr
+            sys.stdin = old_stdin
+            clickpkg.termui.visible_prompt_func = old_visible_prompt_func
+            clickpkg.termui.hidden_prompt_func = old_hidden_prompt_func
+            clickpkg.termui._getchar = old__getchar_func
+            clickpkg.utils.should_strip_ansi = old_should_strip_ansi
+            clickpkg.formatting.FORCED_WIDTH = old_forced_width
+
+    def invoke(self, cli, args=None, input=None, env=None,
+               catch_exceptions=True, color=False, mix_stderr=False, **extra):
+        """Invokes a command in an isolated environment.  The arguments are
+        forwarded directly to the command line script, the `extra` keyword
+        arguments are passed to the :meth:`~clickpkg.Command.main` function of
+        the command.
+
+        This returns a :class:`Result` object.
+
+        .. versionadded:: 3.0
+           The ``catch_exceptions`` parameter was added.
+
+        .. versionchanged:: 3.0
+           The result object now has an `exc_info` attribute with the
+           traceback if available.
+
+        .. versionadded:: 4.0
+           The ``color`` parameter was added.
+
+        :param cli: the command to invoke
+        :param args: the arguments to invoke. It may be given as an iterable
+                     or a string. When given as string it will be interpreted
+                     as a Unix shell command. More details at
+                     :func:`shlex.split`.
+        :param input: the input data for `sys.stdin`.
+        :param env: the environment overrides.
+        :param catch_exceptions: Whether to catch any other exceptions than
+                                 ``SystemExit``.
+        :param extra: the keyword arguments to pass to :meth:`main`.
+        :param color: whether the output should contain color codes. The
+                      application can still override this explicitly.
+        """
+        exc_info = None
+        with self.isolation(input=input, env=env, color=color) as outstreams:
+            exception = None
+            exit_code = 0
+
+            if isinstance(args, string_types):
+                args = shlex.split(args)
+
+            try:
+                prog_name = extra.pop("prog_name")
+            except KeyError:
+                prog_name = self.get_default_prog_name(cli)
+
+            try:
+                cli.main(args=args or (), prog_name=prog_name, **extra)
+            except SystemExit as e:
+                exc_info = sys.exc_info()
+                exit_code = e.code
+                if exit_code is None:
+                    exit_code = 0
+
+                if exit_code != 0:
+                    exception = e
+
+                if not isinstance(exit_code, int):
+                    sys.stdout.write(str(exit_code))
+                    sys.stdout.write('\n')
+                    exit_code = 1
+
+            except Exception as e:
+                if not catch_exceptions:
+                    raise
+                exception = e
+                exit_code = 1
+                exc_info = sys.exc_info()
+            finally:
+                sys.stdout.flush()
+                stdout = outstreams[0].getvalue()
+                stderr = outstreams[1] and outstreams[1].getvalue()
+
+        return Result(runner=self,
+                      stdout_bytes=stdout,
+                      stderr_bytes=stderr,
+                      exit_code=exit_code,
+                      exception=exception,
+                      exc_info=exc_info)
+
+    @contextlib.contextmanager
+    def isolated_filesystem(self):
+        """A context manager that creates a temporary folder and changes
+        the current working directory to it for isolated filesystem tests.
+        """
+        cwd = os.getcwd()
+        t = tempfile.mkdtemp()
+        os.chdir(t)
+        try:
+            yield t
+        finally:
+            os.chdir(cwd)
+            try:
+                shutil.rmtree(t)
+            except (OSError, IOError):
+                pass
diff --git a/python/click/types.py b/python/click/types.py
new file mode 100644
index 0000000..1f88032
--- /dev/null
+++ b/python/click/types.py
@@ -0,0 +1,668 @@
+import os
+import stat
+from datetime import datetime
+
+from ._compat import open_stream, text_type, filename_to_ui, \
+    get_filesystem_encoding, get_streerror, _get_argv_encoding, PY2
+from .exceptions import BadParameter
+from .utils import safecall, LazyFile
+
+
+class ParamType(object):
+    """Helper for converting values through types.  The following is
+    necessary for a valid type:
+
+    *   it needs a name
+    *   it needs to pass through None unchanged
+    *   it needs to convert from a string
+    *   it needs to convert its result type through unchanged
+        (eg: needs to be idempotent)
+    *   it needs to be able to deal with param and context being `None`.
+        This can be the case when the object is used with prompt
+        inputs.
+    """
+    is_composite = False
+
+    #: the descriptive name of this type
+    name = None
+
+    #: if a list of this type is expected and the value is pulled from a
+    #: string environment variable, this is what splits it up.  `None`
+    #: means any whitespace.  For all parameters the general rule is that
+    #: whitespace splits them up.  The exception are paths and files which
+    #: are split by ``os.path.pathsep`` by default (":" on Unix and ";" on
+    #: Windows).
+    envvar_list_splitter = None
+
+    def __call__(self, value, param=None, ctx=None):
+        if value is not None:
+            return self.convert(value, param, ctx)
+
+    def get_metavar(self, param):
+        """Returns the metavar default for this param if it provides one."""
+
+    def get_missing_message(self, param):
+        """Optionally might return extra information about a missing
+        parameter.
+
+        .. versionadded:: 2.0
+        """
+
+    def convert(self, value, param, ctx):
+        """Converts the value.  This is not invoked for values that are
+        `None` (the missing value).
+        """
+        return value
+
+    def split_envvar_value(self, rv):
+        """Given a value from an environment variable this splits it up
+        into small chunks depending on the defined envvar list splitter.
+
+        If the splitter is set to `None`, which means that whitespace splits,
+        then leading and trailing whitespace is ignored.  Otherwise, leading
+        and trailing splitters usually lead to empty items being included.
+        """
+        return (rv or '').split(self.envvar_list_splitter)
+
+    def fail(self, message, param=None, ctx=None):
+        """Helper method to fail with an invalid value message."""
+        raise BadParameter(message, ctx=ctx, param=param)
+
+
+class CompositeParamType(ParamType):
+    is_composite = True
+
+    @property
+    def arity(self):
+        raise NotImplementedError()
+
+
+class FuncParamType(ParamType):
+
+    def __init__(self, func):
+        self.name = func.__name__
+        self.func = func
+
+    def convert(self, value, param, ctx):
+        try:
+            return self.func(value)
+        except ValueError:
+            try:
+                value = text_type(value)
+            except UnicodeError:
+                value = str(value).decode('utf-8', 'replace')
+            self.fail(value, param, ctx)
+
+
+class UnprocessedParamType(ParamType):
+    name = 'text'
+
+    def convert(self, value, param, ctx):
+        return value
+
+    def __repr__(self):
+        return 'UNPROCESSED'
+
+
+class StringParamType(ParamType):
+    name = 'text'
+
+    def convert(self, value, param, ctx):
+        if isinstance(value, bytes):
+            enc = _get_argv_encoding()
+            try:
+                value = value.decode(enc)
+            except UnicodeError:
+                fs_enc = get_filesystem_encoding()
+                if fs_enc != enc:
+                    try:
+                        value = value.decode(fs_enc)
+                    except UnicodeError:
+                        value = value.decode('utf-8', 'replace')
+            return value
+        return value
+
+    def __repr__(self):
+        return 'STRING'
+
+
+class Choice(ParamType):
+    """The choice type allows a value to be checked against a fixed set
+    of supported values. All of these values have to be strings.
+
+    You should only pass a list or tuple of choices. Other iterables
+    (like generators) may lead to surprising results.
+
+    See :ref:`choice-opts` for an example.
+
+    :param case_sensitive: Set to false to make choices case
+        insensitive. Defaults to true.
+    """
+
+    name = 'choice'
+
+    def __init__(self, choices, case_sensitive=True):
+        self.choices = choices
+        self.case_sensitive = case_sensitive
+
+    def get_metavar(self, param):
+        return '[%s]' % '|'.join(self.choices)
+
+    def get_missing_message(self, param):
+        return 'Choose from:\n\t%s.' % ',\n\t'.join(self.choices)
+
+    def convert(self, value, param, ctx):
+        # Exact match
+        if value in self.choices:
+            return value
+
+        # Match through normalization and case sensitivity
+        # first do token_normalize_func, then lowercase
+        # preserve original `value` to produce an accurate message in
+        # `self.fail`
+        normed_value = value
+        normed_choices = self.choices
+
+        if ctx is not None and \
+           ctx.token_normalize_func is not None:
+            normed_value = ctx.token_normalize_func(value)
+            normed_choices = [ctx.token_normalize_func(choice) for choice in
+                              self.choices]
+
+        if not self.case_sensitive:
+            normed_value = normed_value.lower()
+            normed_choices = [choice.lower() for choice in normed_choices]
+
+        if normed_value in normed_choices:
+            return normed_value
+
+        self.fail('invalid choice: %s. (choose from %s)' %
+                  (value, ', '.join(self.choices)), param, ctx)
+
+    def __repr__(self):
+        return 'Choice(%r)' % list(self.choices)
+
+
+class DateTime(ParamType):
+    """The DateTime type converts date strings into `datetime` objects.
+
+    The format strings which are checked are configurable, but default to some
+    common (non-timezone aware) ISO 8601 formats.
+
+    When specifying *DateTime* formats, you should only pass a list or a tuple.
+    Other iterables, like generators, may lead to surprising results.
+
+    The format strings are processed using ``datetime.strptime``, and this
+    consequently defines the format strings which are allowed.
+
+    Parsing is tried using each format, in order, and the first format which
+    parses successfully is used.
+
+    :param formats: A list or tuple of date format strings, in the order in
+                    which they should be tried. Defaults to
+                    ``'%Y-%m-%d'``, ``'%Y-%m-%dT%H:%M:%S'``,
+                    ``'%Y-%m-%d %H:%M:%S'``.
+    """
+    name = 'datetime'
+
+    def __init__(self, formats=None):
+        self.formats = formats or [
+            '%Y-%m-%d',
+            '%Y-%m-%dT%H:%M:%S',
+            '%Y-%m-%d %H:%M:%S'
+        ]
+
+    def get_metavar(self, param):
+        return '[{}]'.format('|'.join(self.formats))
+
+    def _try_to_convert_date(self, value, format):
+        try:
+            return datetime.strptime(value, format)
+        except ValueError:
+            return None
+
+    def convert(self, value, param, ctx):
+        # Exact match
+        for format in self.formats:
+            dtime = self._try_to_convert_date(value, format)
+            if dtime:
+                return dtime
+
+        self.fail(
+            'invalid datetime format: {}. (choose from {})'.format(
+                value, ', '.join(self.formats)))
+
+    def __repr__(self):
+        return 'DateTime'
+
+
+class IntParamType(ParamType):
+    name = 'integer'
+
+    def convert(self, value, param, ctx):
+        try:
+            return int(value)
+        except (ValueError, UnicodeError):
+            self.fail('%s is not a valid integer' % value, param, ctx)
+
+    def __repr__(self):
+        return 'INT'
+
+
+class IntRange(IntParamType):
+    """A parameter that works similar to :data:`click.INT` but restricts
+    the value to fit into a range.  The default behavior is to fail if the
+    value falls outside the range, but it can also be silently clamped
+    between the two edges.
+
+    See :ref:`ranges` for an example.
+    """
+    name = 'integer range'
+
+    def __init__(self, min=None, max=None, clamp=False):
+        self.min = min
+        self.max = max
+        self.clamp = clamp
+
+    def convert(self, value, param, ctx):
+        rv = IntParamType.convert(self, value, param, ctx)
+        if self.clamp:
+            if self.min is not None and rv < self.min:
+                return self.min
+            if self.max is not None and rv > self.max:
+                return self.max
+        if self.min is not None and rv < self.min or \
+           self.max is not None and rv > self.max:
+            if self.min is None:
+                self.fail('%s is bigger than the maximum valid value '
+                          '%s.' % (rv, self.max), param, ctx)
+            elif self.max is None:
+                self.fail('%s is smaller than the minimum valid value '
+                          '%s.' % (rv, self.min), param, ctx)
+            else:
+                self.fail('%s is not in the valid range of %s to %s.'
+                          % (rv, self.min, self.max), param, ctx)
+        return rv
+
+    def __repr__(self):
+        return 'IntRange(%r, %r)' % (self.min, self.max)
+
+
+class FloatParamType(ParamType):
+    name = 'float'
+
+    def convert(self, value, param, ctx):
+        try:
+            return float(value)
+        except (UnicodeError, ValueError):
+            self.fail('%s is not a valid floating point value' %
+                      value, param, ctx)
+
+    def __repr__(self):
+        return 'FLOAT'
+
+
+class FloatRange(FloatParamType):
+    """A parameter that works similar to :data:`click.FLOAT` but restricts
+    the value to fit into a range.  The default behavior is to fail if the
+    value falls outside the range, but it can also be silently clamped
+    between the two edges.
+
+    See :ref:`ranges` for an example.
+    """
+    name = 'float range'
+
+    def __init__(self, min=None, max=None, clamp=False):
+        self.min = min
+        self.max = max
+        self.clamp = clamp
+
+    def convert(self, value, param, ctx):
+        rv = FloatParamType.convert(self, value, param, ctx)
+        if self.clamp:
+            if self.min is not None and rv < self.min:
+                return self.min
+            if self.max is not None and rv > self.max:
+                return self.max
+        if self.min is not None and rv < self.min or \
+           self.max is not None and rv > self.max:
+            if self.min is None:
+                self.fail('%s is bigger than the maximum valid value '
+                          '%s.' % (rv, self.max), param, ctx)
+            elif self.max is None:
+                self.fail('%s is smaller than the minimum valid value '
+                          '%s.' % (rv, self.min), param, ctx)
+            else:
+                self.fail('%s is not in the valid range of %s to %s.'
+                          % (rv, self.min, self.max), param, ctx)
+        return rv
+
+    def __repr__(self):
+        return 'FloatRange(%r, %r)' % (self.min, self.max)
+
+
+class BoolParamType(ParamType):
+    name = 'boolean'
+
+    def convert(self, value, param, ctx):
+        if isinstance(value, bool):
+            return bool(value)
+        value = value.lower()
+        if value in ('true', 't', '1', 'yes', 'y'):
+            return True
+        elif value in ('false', 'f', '0', 'no', 'n'):
+            return False
+        self.fail('%s is not a valid boolean' % value, param, ctx)
+
+    def __repr__(self):
+        return 'BOOL'
+
+
+class UUIDParameterType(ParamType):
+    name = 'uuid'
+
+    def convert(self, value, param, ctx):
+        import uuid
+        try:
+            if PY2 and isinstance(value, text_type):
+                value = value.encode('ascii')
+            return uuid.UUID(value)
+        except (UnicodeError, ValueError):
+            self.fail('%s is not a valid UUID value' % value, param, ctx)
+
+    def __repr__(self):
+        return 'UUID'
+
+
+class File(ParamType):
+    """Declares a parameter to be a file for reading or writing.  The file
+    is automatically closed once the context tears down (after the command
+    finished working).
+
+    Files can be opened for reading or writing.  The special value ``-``
+    indicates stdin or stdout depending on the mode.
+
+    By default, the file is opened for reading text data, but it can also be
+    opened in binary mode or for writing.  The encoding parameter can be used
+    to force a specific encoding.
+
+    The `lazy` flag controls if the file should be opened immediately or upon
+    first IO. The default is to be non-lazy for standard input and output
+    streams as well as files opened for reading, `lazy` otherwise. When opening a
+    file lazily for reading, it is still opened temporarily for validation, but
+    will not be held open until first IO. lazy is mainly useful when opening
+    for writing to avoid creating the file until it is needed.
+
+    Starting with Click 2.0, files can also be opened atomically in which
+    case all writes go into a separate file in the same folder and upon
+    completion the file will be moved over to the original location.  This
+    is useful if a file regularly read by other users is modified.
+
+    See :ref:`file-args` for more information.
+    """
+    name = 'filename'
+    envvar_list_splitter = os.path.pathsep
+
+    def __init__(self, mode='r', encoding=None, errors='strict', lazy=None,
+                 atomic=False):
+        self.mode = mode
+        self.encoding = encoding
+        self.errors = errors
+        self.lazy = lazy
+        self.atomic = atomic
+
+    def resolve_lazy_flag(self, value):
+        if self.lazy is not None:
+            return self.lazy
+        if value == '-':
+            return False
+        elif 'w' in self.mode:
+            return True
+        return False
+
+    def convert(self, value, param, ctx):
+        try:
+            if hasattr(value, 'read') or hasattr(value, 'write'):
+                return value
+
+            lazy = self.resolve_lazy_flag(value)
+
+            if lazy:
+                f = LazyFile(value, self.mode, self.encoding, self.errors,
+                             atomic=self.atomic)
+                if ctx is not None:
+                    ctx.call_on_close(f.close_intelligently)
+                return f
+
+            f, should_close = open_stream(value, self.mode,
+                                          self.encoding, self.errors,
+                                          atomic=self.atomic)
+            # If a context is provided, we automatically close the file
+            # at the end of the context execution (or flush out).  If a
+            # context does not exist, it's the caller's responsibility to
+            # properly close the file.  This for instance happens when the
+            # type is used with prompts.
+            if ctx is not None:
+                if should_close:
+                    ctx.call_on_close(safecall(f.close))
+                else:
+                    ctx.call_on_close(safecall(f.flush))
+            return f
+        except (IOError, OSError) as e:
+            self.fail('Could not open file: %s: %s' % (
+                filename_to_ui(value),
+                get_streerror(e),
+            ), param, ctx)
+
+
+class Path(ParamType):
+    """The path type is similar to the :class:`File` type but it performs
+    different checks.  First of all, instead of returning an open file
+    handle it returns just the filename.  Secondly, it can perform various
+    basic checks about what the file or directory should be.
+
+    .. versionchanged:: 6.0
+       `allow_dash` was added.
+
+    :param exists: if set to true, the file or directory needs to exist for
+                   this value to be valid.  If this is not required and a
+                   file does indeed not exist, then all further checks are
+                   silently skipped.
+    :param file_okay: controls if a file is a possible value.
+    :param dir_okay: controls if a directory is a possible value.
+    :param writable: if true, a writable check is performed.
+    :param readable: if true, a readable check is performed.
+    :param resolve_path: if this is true, then the path is fully resolved
+                         before the value is passed onwards.  This means
+                         that it's absolute and symlinks are resolved.  It
+                         will not expand a tilde-prefix, as this is
+                         supposed to be done by the shell only.
+    :param allow_dash: If this is set to `True`, a single dash to indicate
+                       standard streams is permitted.
+    :param path_type: optionally a string type that should be used to
+                      represent the path.  The default is `None` which
+                      means the return value will be either bytes or
+                      unicode depending on what makes most sense given the
+                      input data Click deals with.
+    """
+    envvar_list_splitter = os.path.pathsep
+
+    def __init__(self, exists=False, file_okay=True, dir_okay=True,
+                 writable=False, readable=True, resolve_path=False,
+                 allow_dash=False, path_type=None):
+        self.exists = exists
+        self.file_okay = file_okay
+        self.dir_okay = dir_okay
+        self.writable = writable
+        self.readable = readable
+        self.resolve_path = resolve_path
+        self.allow_dash = allow_dash
+        self.type = path_type
+
+        if self.file_okay and not self.dir_okay:
+            self.name = 'file'
+            self.path_type = 'File'
+        elif self.dir_okay and not self.file_okay:
+            self.name = 'directory'
+            self.path_type = 'Directory'
+        else:
+            self.name = 'path'
+            self.path_type = 'Path'
+
+    def coerce_path_result(self, rv):
+        if self.type is not None and not isinstance(rv, self.type):
+            if self.type is text_type:
+                rv = rv.decode(get_filesystem_encoding())
+            else:
+                rv = rv.encode(get_filesystem_encoding())
+        return rv
+
+    def convert(self, value, param, ctx):
+        rv = value
+
+        is_dash = self.file_okay and self.allow_dash and rv in (b'-', '-')
+
+        if not is_dash:
+            if self.resolve_path:
+                rv = os.path.realpath(rv)
+
+            try:
+                st = os.stat(rv)
+            except OSError:
+                if not self.exists:
+                    return self.coerce_path_result(rv)
+                self.fail('%s "%s" does not exist.' % (
+                    self.path_type,
+                    filename_to_ui(value)
+                ), param, ctx)
+
+            if not self.file_okay and stat.S_ISREG(st.st_mode):
+                self.fail('%s "%s" is a file.' % (
+                    self.path_type,
+                    filename_to_ui(value)
+                ), param, ctx)
+            if not self.dir_okay and stat.S_ISDIR(st.st_mode):
+                self.fail('%s "%s" is a directory.' % (
+                    self.path_type,
+                    filename_to_ui(value)
+                ), param, ctx)
+            if self.writable and not os.access(value, os.W_OK):
+                self.fail('%s "%s" is not writable.' % (
+                    self.path_type,
+                    filename_to_ui(value)
+                ), param, ctx)
+            if self.readable and not os.access(value, os.R_OK):
+                self.fail('%s "%s" is not readable.' % (
+                    self.path_type,
+                    filename_to_ui(value)
+                ), param, ctx)
+
+        return self.coerce_path_result(rv)
+
+
+class Tuple(CompositeParamType):
+    """The default behavior of Click is to apply a type on a value directly.
+    This works well in most cases, except for when `nargs` is set to a fixed
+    count and different types should be used for different items.  In this
+    case the :class:`Tuple` type can be used.  This type can only be used
+    if `nargs` is set to a fixed number.
+
+    For more information see :ref:`tuple-type`.
+
+    This can be selected by using a Python tuple literal as a type.
+
+    :param types: a list of types that should be used for the tuple items.
+    """
+
+    def __init__(self, types):
+        self.types = [convert_type(ty) for ty in types]
+
+    @property
+    def name(self):
+        return "<" + " ".join(ty.name for ty in self.types) + ">"
+
+    @property
+    def arity(self):
+        return len(self.types)
+
+    def convert(self, value, param, ctx):
+        if len(value) != len(self.types):
+            raise TypeError('It would appear that nargs is set to conflict '
+                            'with the composite type arity.')
+        return tuple(ty(x, param, ctx) for ty, x in zip(self.types, value))
+
+
+def convert_type(ty, default=None):
+    """Converts a callable or python ty into the most appropriate param
+    ty.
+    """
+    guessed_type = False
+    if ty is None and default is not None:
+        if isinstance(default, tuple):
+            ty = tuple(map(type, default))
+        else:
+            ty = type(default)
+        guessed_type = True
+
+    if isinstance(ty, tuple):
+        return Tuple(ty)
+    if isinstance(ty, ParamType):
+        return ty
+    if ty is text_type or ty is str or ty is None:
+        return STRING
+    if ty is int:
+        return INT
+    # Booleans are only okay if not guessed.  This is done because for
+    # flags the default value is actually a bit of a lie in that it
+    # indicates which of the flags is the one we want.  See get_default()
+    # for more information.
+    if ty is bool and not guessed_type:
+        return BOOL
+    if ty is float:
+        return FLOAT
+    if guessed_type:
+        return STRING
+
+    # Catch a common mistake
+    if __debug__:
+        try:
+            if issubclass(ty, ParamType):
+                raise AssertionError('Attempted to use an uninstantiated '
+                                     'parameter type (%s).' % ty)
+        except TypeError:
+            pass
+    return FuncParamType(ty)
+
+
+#: A dummy parameter type that just does nothing.  From a user's
+#: perspective this appears to just be the same as `STRING` but internally
+#: no string conversion takes place.  This is necessary to achieve the
+#: same bytes/unicode behavior on Python 2/3 in situations where you want
+#: to not convert argument types.  This is usually useful when working
+#: with file paths as they can appear in bytes and unicode.
+#:
+#: For path related uses the :class:`Path` type is a better choice but
+#: there are situations where an unprocessed type is useful which is why
+#: it is is provided.
+#:
+#: .. versionadded:: 4.0
+UNPROCESSED = UnprocessedParamType()
+
+#: A unicode string parameter type which is the implicit default.  This
+#: can also be selected by using ``str`` as type.
+STRING = StringParamType()
+
+#: An integer parameter.  This can also be selected by using ``int`` as
+#: type.
+INT = IntParamType()
+
+#: A floating point value parameter.  This can also be selected by using
+#: ``float`` as type.
+FLOAT = FloatParamType()
+
+#: A boolean parameter.  This is the default for boolean flags.  This can
+#: also be selected by using ``bool`` as a type.
+BOOL = BoolParamType()
+
+#: A UUID parameter.
+UUID = UUIDParameterType()
diff --git a/python/click/utils.py b/python/click/utils.py
new file mode 100644
index 0000000..fc84369
--- /dev/null
+++ b/python/click/utils.py
@@ -0,0 +1,440 @@
+import os
+import sys
+
+from .globals import resolve_color_default
+
+from ._compat import text_type, open_stream, get_filesystem_encoding, \
+    get_streerror, string_types, PY2, binary_streams, text_streams, \
+    filename_to_ui, auto_wrap_for_ansi, strip_ansi, should_strip_ansi, \
+    _default_text_stdout, _default_text_stderr, is_bytes, WIN
+
+if not PY2:
+    from ._compat import _find_binary_writer
+elif WIN:
+    from ._winconsole import _get_windows_argv, \
+         _hash_py_argv, _initial_argv_hash
+
+
+echo_native_types = string_types + (bytes, bytearray)
+
+
+def _posixify(name):
+    return '-'.join(name.split()).lower()
+
+
+def safecall(func):
+    """Wraps a function so that it swallows exceptions."""
+    def wrapper(*args, **kwargs):
+        try:
+            return func(*args, **kwargs)
+        except Exception:
+            pass
+    return wrapper
+
+
+def make_str(value):
+    """Converts a value into a valid string."""
+    if isinstance(value, bytes):
+        try:
+            return value.decode(get_filesystem_encoding())
+        except UnicodeError:
+            return value.decode('utf-8', 'replace')
+    return text_type(value)
+
+
+def make_default_short_help(help, max_length=45):
+    """Return a condensed version of help string."""
+    words = help.split()
+    total_length = 0
+    result = []
+    done = False
+
+    for word in words:
+        if word[-1:] == '.':
+            done = True
+        new_length = result and 1 + len(word) or len(word)
+        if total_length + new_length > max_length:
+            result.append('...')
+            done = True
+        else:
+            if result:
+                result.append(' ')
+            result.append(word)
+        if done:
+            break
+        total_length += new_length
+
+    return ''.join(result)
+
+
+class LazyFile(object):
+    """A lazy file works like a regular file but it does not fully open
+    the file but it does perform some basic checks early to see if the
+    filename parameter does make sense.  This is useful for safely opening
+    files for writing.
+    """
+
+    def __init__(self, filename, mode='r', encoding=None, errors='strict',
+                 atomic=False):
+        self.name = filename
+        self.mode = mode
+        self.encoding = encoding
+        self.errors = errors
+        self.atomic = atomic
+
+        if filename == '-':
+            self._f, self.should_close = open_stream(filename, mode,
+                                                     encoding, errors)
+        else:
+            if 'r' in mode:
+                # Open and close the file in case we're opening it for
+                # reading so that we can catch at least some errors in
+                # some cases early.
+                open(filename, mode).close()
+            self._f = None
+            self.should_close = True
+
+    def __getattr__(self, name):
+        return getattr(self.open(), name)
+
+    def __repr__(self):
+        if self._f is not None:
+            return repr(self._f)
+        return '<unopened file %r %s>' % (self.name, self.mode)
+
+    def open(self):
+        """Opens the file if it's not yet open.  This call might fail with
+        a :exc:`FileError`.  Not handling this error will produce an error
+        that Click shows.
+        """
+        if self._f is not None:
+            return self._f
+        try:
+            rv, self.should_close = open_stream(self.name, self.mode,
+                                                self.encoding,
+                                                self.errors,
+                                                atomic=self.atomic)
+        except (IOError, OSError) as e:
+            from .exceptions import FileError
+            raise FileError(self.name, hint=get_streerror(e))
+        self._f = rv
+        return rv
+
+    def close(self):
+        """Closes the underlying file, no matter what."""
+        if self._f is not None:
+            self._f.close()
+
+    def close_intelligently(self):
+        """This function only closes the file if it was opened by the lazy
+        file wrapper.  For instance this will never close stdin.
+        """
+        if self.should_close:
+            self.close()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.close_intelligently()
+
+    def __iter__(self):
+        self.open()
+        return iter(self._f)
+
+
+class KeepOpenFile(object):
+
+    def __init__(self, file):
+        self._file = file
+
+    def __getattr__(self, name):
+        return getattr(self._file, name)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        pass
+
+    def __repr__(self):
+        return repr(self._file)
+
+    def __iter__(self):
+        return iter(self._file)
+
+
+def echo(message=None, file=None, nl=True, err=False, color=None):
+    """Prints a message plus a newline to the given file or stdout.  On
+    first sight, this looks like the print function, but it has improved
+    support for handling Unicode and binary data that does not fail no
+    matter how badly configured the system is.
+
+    Primarily it means that you can print binary data as well as Unicode
+    data on both 2.x and 3.x to the given file in the most appropriate way
+    possible.  This is a very carefree function in that it will try its
+    best to not fail.  As of Click 6.0 this includes support for unicode
+    output on the Windows console.
+
+    In addition to that, if `colorama`_ is installed, the echo function will
+    also support clever handling of ANSI codes.  Essentially it will then
+    do the following:
+
+    -   add transparent handling of ANSI color codes on Windows.
+    -   hide ANSI codes automatically if the destination file is not a
+        terminal.
+
+    .. _colorama: https://pypi.org/project/colorama/
+
+    .. versionchanged:: 6.0
+       As of Click 6.0 the echo function will properly support unicode
+       output on the windows console.  Not that click does not modify
+       the interpreter in any way which means that `sys.stdout` or the
+       print statement or function will still not provide unicode support.
+
+    .. versionchanged:: 2.0
+       Starting with version 2.0 of Click, the echo function will work
+       with colorama if it's installed.
+
+    .. versionadded:: 3.0
+       The `err` parameter was added.
+
+    .. versionchanged:: 4.0
+       Added the `color` flag.
+
+    :param message: the message to print
+    :param file: the file to write to (defaults to ``stdout``)
+    :param err: if set to true the file defaults to ``stderr`` instead of
+                ``stdout``.  This is faster and easier than calling
+                :func:`get_text_stderr` yourself.
+    :param nl: if set to `True` (the default) a newline is printed afterwards.
+    :param color: controls if the terminal supports ANSI colors or not.  The
+                  default is autodetection.
+    """
+    if file is None:
+        if err:
+            file = _default_text_stderr()
+        else:
+            file = _default_text_stdout()
+
+    # Convert non bytes/text into the native string type.
+    if message is not None and not isinstance(message, echo_native_types):
+        message = text_type(message)
+
+    if nl:
+        message = message or u''
+        if isinstance(message, text_type):
+            message += u'\n'
+        else:
+            message += b'\n'
+
+    # If there is a message, and we're in Python 3, and the value looks
+    # like bytes, we manually need to find the binary stream and write the
+    # message in there.  This is done separately so that most stream
+    # types will work as you would expect.  Eg: you can write to StringIO
+    # for other cases.
+    if message and not PY2 and is_bytes(message):
+        binary_file = _find_binary_writer(file)
+        if binary_file is not None:
+            file.flush()
+            binary_file.write(message)
+            binary_file.flush()
+            return
+
+    # ANSI-style support.  If there is no message or we are dealing with
+    # bytes nothing is happening.  If we are connected to a file we want
+    # to strip colors.  If we are on windows we either wrap the stream
+    # to strip the color or we use the colorama support to translate the
+    # ansi codes to API calls.
+    if message and not is_bytes(message):
+        color = resolve_color_default(color)
+        if should_strip_ansi(file, color):
+            message = strip_ansi(message)
+        elif WIN:
+            if auto_wrap_for_ansi is not None:
+                file = auto_wrap_for_ansi(file)
+            elif not color:
+                message = strip_ansi(message)
+
+    if message:
+        file.write(message)
+    file.flush()
+
+
+def get_binary_stream(name):
+    """Returns a system stream for byte processing.  This essentially
+    returns the stream from the sys module with the given name but it
+    solves some compatibility issues between different Python versions.
+    Primarily this function is necessary for getting binary streams on
+    Python 3.
+
+    :param name: the name of the stream to open.  Valid names are ``'stdin'``,
+                 ``'stdout'`` and ``'stderr'``
+    """
+    opener = binary_streams.get(name)
+    if opener is None:
+        raise TypeError('Unknown standard stream %r' % name)
+    return opener()
+
+
+def get_text_stream(name, encoding=None, errors='strict'):
+    """Returns a system stream for text processing.  This usually returns
+    a wrapped stream around a binary stream returned from
+    :func:`get_binary_stream` but it also can take shortcuts on Python 3
+    for already correctly configured streams.
+
+    :param name: the name of the stream to open.  Valid names are ``'stdin'``,
+                 ``'stdout'`` and ``'stderr'``
+    :param encoding: overrides the detected default encoding.
+    :param errors: overrides the default error mode.
+    """
+    opener = text_streams.get(name)
+    if opener is None:
+        raise TypeError('Unknown standard stream %r' % name)
+    return opener(encoding, errors)
+
+
+def open_file(filename, mode='r', encoding=None, errors='strict',
+              lazy=False, atomic=False):
+    """This is similar to how the :class:`File` works but for manual
+    usage.  Files are opened non lazy by default.  This can open regular
+    files as well as stdin/stdout if ``'-'`` is passed.
+
+    If stdin/stdout is returned the stream is wrapped so that the context
+    manager will not close the stream accidentally.  This makes it possible
+    to always use the function like this without having to worry to
+    accidentally close a standard stream::
+
+        with open_file(filename) as f:
+            ...
+
+    .. versionadded:: 3.0
+
+    :param filename: the name of the file to open (or ``'-'`` for stdin/stdout).
+    :param mode: the mode in which to open the file.
+    :param encoding: the encoding to use.
+    :param errors: the error handling for this file.
+    :param lazy: can be flipped to true to open the file lazily.
+    :param atomic: in atomic mode writes go into a temporary file and it's
+                   moved on close.
+    """
+    if lazy:
+        return LazyFile(filename, mode, encoding, errors, atomic=atomic)
+    f, should_close = open_stream(filename, mode, encoding, errors,
+                                  atomic=atomic)
+    if not should_close:
+        f = KeepOpenFile(f)
+    return f
+
+
+def get_os_args():
+    """This returns the argument part of sys.argv in the most appropriate
+    form for processing.  What this means is that this return value is in
+    a format that works for Click to process but does not necessarily
+    correspond well to what's actually standard for the interpreter.
+
+    On most environments the return value is ``sys.argv[:1]`` unchanged.
+    However if you are on Windows and running Python 2 the return value
+    will actually be a list of unicode strings instead because the
+    default behavior on that platform otherwise will not be able to
+    carry all possible values that sys.argv can have.
+
+    .. versionadded:: 6.0
+    """
+    # We can only extract the unicode argv if sys.argv has not been
+    # changed since the startup of the application.
+    if PY2 and WIN and _initial_argv_hash == _hash_py_argv():
+        return _get_windows_argv()
+    return sys.argv[1:]
+
+
+def format_filename(filename, shorten=False):
+    """Formats a filename for user display.  The main purpose of this
+    function is to ensure that the filename can be displayed at all.  This
+    will decode the filename to unicode if necessary in a way that it will
+    not fail.  Optionally, it can shorten the filename to not include the
+    full path to the filename.
+
+    :param filename: formats a filename for UI display.  This will also convert
+                     the filename into unicode without failing.
+    :param shorten: this optionally shortens the filename to strip of the
+                    path that leads up to it.
+    """
+    if shorten:
+        filename = os.path.basename(filename)
+    return filename_to_ui(filename)
+
+
+def get_app_dir(app_name, roaming=True, force_posix=False):
+    r"""Returns the config folder for the application.  The default behavior
+    is to return whatever is most appropriate for the operating system.
+
+    To give you an idea, for an app called ``"Foo Bar"``, something like
+    the following folders could be returned:
+
+    Mac OS X:
+      ``~/Library/Application Support/Foo Bar``
+    Mac OS X (POSIX):
+      ``~/.foo-bar``
+    Unix:
+      ``~/.config/foo-bar``
+    Unix (POSIX):
+      ``~/.foo-bar``
+    Win XP (roaming):
+      ``C:\Documents and Settings\<user>\Local Settings\Application Data\Foo Bar``
+    Win XP (not roaming):
+      ``C:\Documents and Settings\<user>\Application Data\Foo Bar``
+    Win 7 (roaming):
+      ``C:\Users\<user>\AppData\Roaming\Foo Bar``
+    Win 7 (not roaming):
+      ``C:\Users\<user>\AppData\Local\Foo Bar``
+
+    .. versionadded:: 2.0
+
+    :param app_name: the application name.  This should be properly capitalized
+                     and can contain whitespace.
+    :param roaming: controls if the folder should be roaming or not on Windows.
+                    Has no affect otherwise.
+    :param force_posix: if this is set to `True` then on any POSIX system the
+                        folder will be stored in the home folder with a leading
+                        dot instead of the XDG config home or darwin's
+                        application support folder.
+    """
+    if WIN:
+        key = roaming and 'APPDATA' or 'LOCALAPPDATA'
+        folder = os.environ.get(key)
+        if folder is None:
+            folder = os.path.expanduser('~')
+        return os.path.join(folder, app_name)
+    if force_posix:
+        return os.path.join(os.path.expanduser('~/.' + _posixify(app_name)))
+    if sys.platform == 'darwin':
+        return os.path.join(os.path.expanduser(
+            '~/Library/Application Support'), app_name)
+    return os.path.join(
+        os.environ.get('XDG_CONFIG_HOME', os.path.expanduser('~/.config')),
+        _posixify(app_name))
+
+
+class PacifyFlushWrapper(object):
+    """This wrapper is used to catch and suppress BrokenPipeErrors resulting
+    from ``.flush()`` being called on broken pipe during the shutdown/final-GC
+    of the Python interpreter. Notably ``.flush()`` is always called on
+    ``sys.stdout`` and ``sys.stderr``. So as to have minimal impact on any
+    other cleanup code, and the case where the underlying file is not a broken
+    pipe, all calls and attributes are proxied.
+    """
+
+    def __init__(self, wrapped):
+        self.wrapped = wrapped
+
+    def flush(self):
+        try:
+            self.wrapped.flush()
+        except IOError as e:
+            import errno
+            if e.errno != errno.EPIPE:
+                raise
+
+    def __getattr__(self, attr):
+        return getattr(self.wrapped, attr)
diff --git a/python/flask/__init__.py b/python/flask/__init__.py
new file mode 100644
index 0000000..59f0fff
--- /dev/null
+++ b/python/flask/__init__.py
@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+"""
+    flask
+    ~~~~~
+
+    A microframework based on Werkzeug.  It's extensively documented
+    and follows best practice patterns.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+__version__ = '1.0.3'
+
+# utilities we import from Werkzeug and Jinja2 that are unused
+# in the module but are exported as public interface.
+from werkzeug.exceptions import abort
+from werkzeug.utils import redirect
+from jinja2 import Markup, escape
+
+from .app import Flask, Request, Response
+from .config import Config
+from .helpers import url_for, flash, send_file, send_from_directory, \
+     get_flashed_messages, get_template_attribute, make_response, safe_join, \
+     stream_with_context
+from .globals import current_app, g, request, session, _request_ctx_stack, \
+     _app_ctx_stack
+from .ctx import has_request_context, has_app_context, \
+     after_this_request, copy_current_request_context
+from .blueprints import Blueprint
+from .templating import render_template, render_template_string
+
+# the signals
+from .signals import signals_available, template_rendered, request_started, \
+     request_finished, got_request_exception, request_tearing_down, \
+     appcontext_tearing_down, appcontext_pushed, \
+     appcontext_popped, message_flashed, before_render_template
+
+# We're not exposing the actual json module but a convenient wrapper around
+# it.
+from . import json
+
+# This was the only thing that Flask used to export at one point and it had
+# a more generic name.
+jsonify = json.jsonify
+
+# backwards compat, goes away in 1.0
+from .sessions import SecureCookieSession as Session
+json_available = True
diff --git a/python/flask/__main__.py b/python/flask/__main__.py
new file mode 100644
index 0000000..4aee654
--- /dev/null
+++ b/python/flask/__main__.py
@@ -0,0 +1,14 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.__main__
+    ~~~~~~~~~~~~~~
+
+    Alias for flask.run for the command line.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+if __name__ == '__main__':
+    from .cli import main
+    main(as_module=True)
diff --git a/python/flask/_compat.py b/python/flask/_compat.py
new file mode 100644
index 0000000..dfbaae9
--- /dev/null
+++ b/python/flask/_compat.py
@@ -0,0 +1,101 @@
+# -*- coding: utf-8 -*-
+"""
+    flask._compat
+    ~~~~~~~~~~~~~
+
+    Some py2/py3 compatibility support based on a stripped down
+    version of six so we don't have to depend on a specific version
+    of it.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import sys
+
+PY2 = sys.version_info[0] == 2
+_identity = lambda x: x
+
+
+if not PY2:
+    text_type = str
+    string_types = (str,)
+    integer_types = (int,)
+
+    iterkeys = lambda d: iter(d.keys())
+    itervalues = lambda d: iter(d.values())
+    iteritems = lambda d: iter(d.items())
+
+    from inspect import getfullargspec as getargspec
+    from io import StringIO
+    import collections.abc as collections_abc
+
+    def reraise(tp, value, tb=None):
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+
+    implements_to_string = _identity
+
+else:
+    text_type = unicode
+    string_types = (str, unicode)
+    integer_types = (int, long)
+
+    iterkeys = lambda d: d.iterkeys()
+    itervalues = lambda d: d.itervalues()
+    iteritems = lambda d: d.iteritems()
+
+    from inspect import getargspec
+    from cStringIO import StringIO
+    import collections as collections_abc
+
+    exec('def reraise(tp, value, tb=None):\n raise tp, value, tb')
+
+    def implements_to_string(cls):
+        cls.__unicode__ = cls.__str__
+        cls.__str__ = lambda x: x.__unicode__().encode('utf-8')
+        return cls
+
+
+def with_metaclass(meta, *bases):
+    """Create a base class with a metaclass."""
+    # This requires a bit of explanation: the basic idea is to make a
+    # dummy metaclass for one level of class instantiation that replaces
+    # itself with the actual metaclass.
+    class metaclass(type):
+        def __new__(cls, name, this_bases, d):
+            return meta(name, bases, d)
+    return type.__new__(metaclass, 'temporary_class', (), {})
+
+
+# Certain versions of pypy have a bug where clearing the exception stack
+# breaks the __exit__ function in a very peculiar way.  The second level of
+# exception blocks is necessary because pypy seems to forget to check if an
+# exception happened until the next bytecode instruction?
+#
+# Relevant PyPy bugfix commit:
+# https://bitbucket.org/pypy/pypy/commits/77ecf91c635a287e88e60d8ddb0f4e9df4003301
+# According to ronan on #pypy IRC, it is released in PyPy2 2.3 and later
+# versions.
+#
+# Ubuntu 14.04 has PyPy 2.2.1, which does exhibit this bug.
+BROKEN_PYPY_CTXMGR_EXIT = False
+if hasattr(sys, 'pypy_version_info'):
+    class _Mgr(object):
+        def __enter__(self):
+            return self
+        def __exit__(self, *args):
+            if hasattr(sys, 'exc_clear'):
+                # Python 3 (PyPy3) doesn't have exc_clear
+                sys.exc_clear()
+    try:
+        try:
+            with _Mgr():
+                raise AssertionError()
+        except:
+            raise
+    except TypeError:
+        BROKEN_PYPY_CTXMGR_EXIT = True
+    except AssertionError:
+        pass
diff --git a/python/flask/app.py b/python/flask/app.py
new file mode 100644
index 0000000..c570a95
--- /dev/null
+++ b/python/flask/app.py
@@ -0,0 +1,2334 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.app
+    ~~~~~~~~~
+
+    This module implements the central WSGI application object.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import os
+import sys
+import warnings
+from datetime import timedelta
+from functools import update_wrapper
+from itertools import chain
+from threading import Lock
+
+from werkzeug.datastructures import Headers, ImmutableDict
+from werkzeug.exceptions import BadRequest, BadRequestKeyError, HTTPException, \
+    InternalServerError, MethodNotAllowed, default_exceptions
+from werkzeug.routing import BuildError, Map, RequestRedirect, \
+    RoutingException, Rule
+
+from . import cli, json
+from ._compat import integer_types, reraise, string_types, text_type
+from .config import Config, ConfigAttribute
+from .ctx import AppContext, RequestContext, _AppCtxGlobals
+from .globals import _request_ctx_stack, g, request, session
+from .helpers import (
+    _PackageBoundObject,
+    _endpoint_from_view_func, find_package, get_env, get_debug_flag,
+    get_flashed_messages, locked_cached_property, url_for, get_load_dotenv
+)
+from .logging import create_logger
+from .sessions import SecureCookieSessionInterface
+from .signals import appcontext_tearing_down, got_request_exception, \
+    request_finished, request_started, request_tearing_down
+from .templating import DispatchingJinjaLoader, Environment, \
+    _default_template_ctx_processor
+from .wrappers import Request, Response
+
+# a singleton sentinel value for parameter defaults
+_sentinel = object()
+
+
+def _make_timedelta(value):
+    if not isinstance(value, timedelta):
+        return timedelta(seconds=value)
+    return value
+
+
+def setupmethod(f):
+    """Wraps a method so that it performs a check in debug mode if the
+    first request was already handled.
+    """
+    def wrapper_func(self, *args, **kwargs):
+        if self.debug and self._got_first_request:
+            raise AssertionError('A setup function was called after the '
+                'first request was handled.  This usually indicates a bug '
+                'in the application where a module was not imported '
+                'and decorators or other functionality was called too late.\n'
+                'To fix this make sure to import all your view modules, '
+                'database models and everything related at a central place '
+                'before the application starts serving requests.')
+        return f(self, *args, **kwargs)
+    return update_wrapper(wrapper_func, f)
+
+
+class Flask(_PackageBoundObject):
+    """The flask object implements a WSGI application and acts as the central
+    object.  It is passed the name of the module or package of the
+    application.  Once it is created it will act as a central registry for
+    the view functions, the URL rules, template configuration and much more.
+
+    The name of the package is used to resolve resources from inside the
+    package or the folder the module is contained in depending on if the
+    package parameter resolves to an actual python package (a folder with
+    an :file:`__init__.py` file inside) or a standard module (just a ``.py`` file).
+
+    For more information about resource loading, see :func:`open_resource`.
+
+    Usually you create a :class:`Flask` instance in your main module or
+    in the :file:`__init__.py` file of your package like this::
+
+        from flask import Flask
+        app = Flask(__name__)
+
+    .. admonition:: About the First Parameter
+
+        The idea of the first parameter is to give Flask an idea of what
+        belongs to your application.  This name is used to find resources
+        on the filesystem, can be used by extensions to improve debugging
+        information and a lot more.
+
+        So it's important what you provide there.  If you are using a single
+        module, `__name__` is always the correct value.  If you however are
+        using a package, it's usually recommended to hardcode the name of
+        your package there.
+
+        For example if your application is defined in :file:`yourapplication/app.py`
+        you should create it with one of the two versions below::
+
+            app = Flask('yourapplication')
+            app = Flask(__name__.split('.')[0])
+
+        Why is that?  The application will work even with `__name__`, thanks
+        to how resources are looked up.  However it will make debugging more
+        painful.  Certain extensions can make assumptions based on the
+        import name of your application.  For example the Flask-SQLAlchemy
+        extension will look for the code in your application that triggered
+        an SQL query in debug mode.  If the import name is not properly set
+        up, that debugging information is lost.  (For example it would only
+        pick up SQL queries in `yourapplication.app` and not
+        `yourapplication.views.frontend`)
+
+    .. versionadded:: 0.7
+       The `static_url_path`, `static_folder`, and `template_folder`
+       parameters were added.
+
+    .. versionadded:: 0.8
+       The `instance_path` and `instance_relative_config` parameters were
+       added.
+
+    .. versionadded:: 0.11
+       The `root_path` parameter was added.
+
+    .. versionadded:: 1.0
+       The ``host_matching`` and ``static_host`` parameters were added.
+
+    .. versionadded:: 1.0
+       The ``subdomain_matching`` parameter was added. Subdomain
+       matching needs to be enabled manually now. Setting
+       :data:`SERVER_NAME` does not implicitly enable it.
+
+    :param import_name: the name of the application package
+    :param static_url_path: can be used to specify a different path for the
+                            static files on the web.  Defaults to the name
+                            of the `static_folder` folder.
+    :param static_folder: the folder with static files that should be served
+                          at `static_url_path`.  Defaults to the ``'static'``
+                          folder in the root path of the application.
+    :param static_host: the host to use when adding the static route.
+        Defaults to None. Required when using ``host_matching=True``
+        with a ``static_folder`` configured.
+    :param host_matching: set ``url_map.host_matching`` attribute.
+        Defaults to False.
+    :param subdomain_matching: consider the subdomain relative to
+        :data:`SERVER_NAME` when matching routes. Defaults to False.
+    :param template_folder: the folder that contains the templates that should
+                            be used by the application.  Defaults to
+                            ``'templates'`` folder in the root path of the
+                            application.
+    :param instance_path: An alternative instance path for the application.
+                          By default the folder ``'instance'`` next to the
+                          package or module is assumed to be the instance
+                          path.
+    :param instance_relative_config: if set to ``True`` relative filenames
+                                     for loading the config are assumed to
+                                     be relative to the instance path instead
+                                     of the application root.
+    :param root_path: Flask by default will automatically calculate the path
+                      to the root of the application.  In certain situations
+                      this cannot be achieved (for instance if the package
+                      is a Python 3 namespace package) and needs to be
+                      manually defined.
+    """
+
+    #: The class that is used for request objects.  See :class:`~flask.Request`
+    #: for more information.
+    request_class = Request
+
+    #: The class that is used for response objects.  See
+    #: :class:`~flask.Response` for more information.
+    response_class = Response
+
+    #: The class that is used for the Jinja environment.
+    #:
+    #: .. versionadded:: 0.11
+    jinja_environment = Environment
+
+    #: The class that is used for the :data:`~flask.g` instance.
+    #:
+    #: Example use cases for a custom class:
+    #:
+    #: 1. Store arbitrary attributes on flask.g.
+    #: 2. Add a property for lazy per-request database connectors.
+    #: 3. Return None instead of AttributeError on unexpected attributes.
+    #: 4. Raise exception if an unexpected attr is set, a "controlled" flask.g.
+    #:
+    #: In Flask 0.9 this property was called `request_globals_class` but it
+    #: was changed in 0.10 to :attr:`app_ctx_globals_class` because the
+    #: flask.g object is now application context scoped.
+    #:
+    #: .. versionadded:: 0.10
+    app_ctx_globals_class = _AppCtxGlobals
+
+    #: The class that is used for the ``config`` attribute of this app.
+    #: Defaults to :class:`~flask.Config`.
+    #:
+    #: Example use cases for a custom class:
+    #:
+    #: 1. Default values for certain config options.
+    #: 2. Access to config values through attributes in addition to keys.
+    #:
+    #: .. versionadded:: 0.11
+    config_class = Config
+
+    #: The testing flag.  Set this to ``True`` to enable the test mode of
+    #: Flask extensions (and in the future probably also Flask itself).
+    #: For example this might activate test helpers that have an
+    #: additional runtime cost which should not be enabled by default.
+    #:
+    #: If this is enabled and PROPAGATE_EXCEPTIONS is not changed from the
+    #: default it's implicitly enabled.
+    #:
+    #: This attribute can also be configured from the config with the
+    #: ``TESTING`` configuration key.  Defaults to ``False``.
+    testing = ConfigAttribute('TESTING')
+
+    #: If a secret key is set, cryptographic components can use this to
+    #: sign cookies and other things. Set this to a complex random value
+    #: when you want to use the secure cookie for instance.
+    #:
+    #: This attribute can also be configured from the config with the
+    #: :data:`SECRET_KEY` configuration key. Defaults to ``None``.
+    secret_key = ConfigAttribute('SECRET_KEY')
+
+    #: The secure cookie uses this for the name of the session cookie.
+    #:
+    #: This attribute can also be configured from the config with the
+    #: ``SESSION_COOKIE_NAME`` configuration key.  Defaults to ``'session'``
+    session_cookie_name = ConfigAttribute('SESSION_COOKIE_NAME')
+
+    #: A :class:`~datetime.timedelta` which is used to set the expiration
+    #: date of a permanent session.  The default is 31 days which makes a
+    #: permanent session survive for roughly one month.
+    #:
+    #: This attribute can also be configured from the config with the
+    #: ``PERMANENT_SESSION_LIFETIME`` configuration key.  Defaults to
+    #: ``timedelta(days=31)``
+    permanent_session_lifetime = ConfigAttribute('PERMANENT_SESSION_LIFETIME',
+        get_converter=_make_timedelta)
+
+    #: A :class:`~datetime.timedelta` which is used as default cache_timeout
+    #: for the :func:`send_file` functions. The default is 12 hours.
+    #:
+    #: This attribute can also be configured from the config with the
+    #: ``SEND_FILE_MAX_AGE_DEFAULT`` configuration key. This configuration
+    #: variable can also be set with an integer value used as seconds.
+    #: Defaults to ``timedelta(hours=12)``
+    send_file_max_age_default = ConfigAttribute('SEND_FILE_MAX_AGE_DEFAULT',
+        get_converter=_make_timedelta)
+
+    #: Enable this if you want to use the X-Sendfile feature.  Keep in
+    #: mind that the server has to support this.  This only affects files
+    #: sent with the :func:`send_file` method.
+    #:
+    #: .. versionadded:: 0.2
+    #:
+    #: This attribute can also be configured from the config with the
+    #: ``USE_X_SENDFILE`` configuration key.  Defaults to ``False``.
+    use_x_sendfile = ConfigAttribute('USE_X_SENDFILE')
+
+    #: The JSON encoder class to use.  Defaults to :class:`~flask.json.JSONEncoder`.
+    #:
+    #: .. versionadded:: 0.10
+    json_encoder = json.JSONEncoder
+
+    #: The JSON decoder class to use.  Defaults to :class:`~flask.json.JSONDecoder`.
+    #:
+    #: .. versionadded:: 0.10
+    json_decoder = json.JSONDecoder
+
+    #: Options that are passed directly to the Jinja2 environment.
+    jinja_options = ImmutableDict(
+        extensions=['jinja2.ext.autoescape', 'jinja2.ext.with_']
+    )
+
+    #: Default configuration parameters.
+    default_config = ImmutableDict({
+        'ENV':                                  None,
+        'DEBUG':                                None,
+        'TESTING':                              False,
+        'PROPAGATE_EXCEPTIONS':                 None,
+        'PRESERVE_CONTEXT_ON_EXCEPTION':        None,
+        'SECRET_KEY':                           None,
+        'PERMANENT_SESSION_LIFETIME':           timedelta(days=31),
+        'USE_X_SENDFILE':                       False,
+        'SERVER_NAME':                          None,
+        'APPLICATION_ROOT':                     '/',
+        'SESSION_COOKIE_NAME':                  'session',
+        'SESSION_COOKIE_DOMAIN':                None,
+        'SESSION_COOKIE_PATH':                  None,
+        'SESSION_COOKIE_HTTPONLY':              True,
+        'SESSION_COOKIE_SECURE':                False,
+        'SESSION_COOKIE_SAMESITE':              None,
+        'SESSION_REFRESH_EACH_REQUEST':         True,
+        'MAX_CONTENT_LENGTH':                   None,
+        'SEND_FILE_MAX_AGE_DEFAULT':            timedelta(hours=12),
+        'TRAP_BAD_REQUEST_ERRORS':              None,
+        'TRAP_HTTP_EXCEPTIONS':                 False,
+        'EXPLAIN_TEMPLATE_LOADING':             False,
+        'PREFERRED_URL_SCHEME':                 'http',
+        'JSON_AS_ASCII':                        True,
+        'JSON_SORT_KEYS':                       True,
+        'JSONIFY_PRETTYPRINT_REGULAR':          False,
+        'JSONIFY_MIMETYPE':                     'application/json',
+        'TEMPLATES_AUTO_RELOAD':                None,
+        'MAX_COOKIE_SIZE': 4093,
+    })
+
+    #: The rule object to use for URL rules created.  This is used by
+    #: :meth:`add_url_rule`.  Defaults to :class:`werkzeug.routing.Rule`.
+    #:
+    #: .. versionadded:: 0.7
+    url_rule_class = Rule
+
+    #: the test client that is used with when `test_client` is used.
+    #:
+    #: .. versionadded:: 0.7
+    test_client_class = None
+
+    #: The :class:`~click.testing.CliRunner` subclass, by default
+    #: :class:`~flask.testing.FlaskCliRunner` that is used by
+    #: :meth:`test_cli_runner`. Its ``__init__`` method should take a
+    #: Flask app object as the first argument.
+    #:
+    #: .. versionadded:: 1.0
+    test_cli_runner_class = None
+
+    #: the session interface to use.  By default an instance of
+    #: :class:`~flask.sessions.SecureCookieSessionInterface` is used here.
+    #:
+    #: .. versionadded:: 0.8
+    session_interface = SecureCookieSessionInterface()
+
+    # TODO remove the next three attrs when Sphinx :inherited-members: works
+    # https://github.com/sphinx-doc/sphinx/issues/741
+
+    #: The name of the package or module that this app belongs to. Do not
+    #: change this once it is set by the constructor.
+    import_name = None
+
+    #: Location of the template files to be added to the template lookup.
+    #: ``None`` if templates should not be added.
+    template_folder = None
+
+    #: Absolute path to the package on the filesystem. Used to look up
+    #: resources contained in the package.
+    root_path = None
+
+    def __init__(
+        self,
+        import_name,
+        static_url_path=None,
+        static_folder='static',
+        static_host=None,
+        host_matching=False,
+        subdomain_matching=False,
+        template_folder='templates',
+        instance_path=None,
+        instance_relative_config=False,
+        root_path=None
+    ):
+        _PackageBoundObject.__init__(
+            self,
+            import_name,
+            template_folder=template_folder,
+            root_path=root_path
+        )
+
+        if static_url_path is not None:
+            self.static_url_path = static_url_path
+
+        if static_folder is not None:
+            self.static_folder = static_folder
+
+        if instance_path is None:
+            instance_path = self.auto_find_instance_path()
+        elif not os.path.isabs(instance_path):
+            raise ValueError(
+                'If an instance path is provided it must be absolute.'
+                ' A relative path was given instead.'
+            )
+
+        #: Holds the path to the instance folder.
+        #:
+        #: .. versionadded:: 0.8
+        self.instance_path = instance_path
+
+        #: The configuration dictionary as :class:`Config`.  This behaves
+        #: exactly like a regular dictionary but supports additional methods
+        #: to load a config from files.
+        self.config = self.make_config(instance_relative_config)
+
+        #: A dictionary of all view functions registered.  The keys will
+        #: be function names which are also used to generate URLs and
+        #: the values are the function objects themselves.
+        #: To register a view function, use the :meth:`route` decorator.
+        self.view_functions = {}
+
+        #: A dictionary of all registered error handlers.  The key is ``None``
+        #: for error handlers active on the application, otherwise the key is
+        #: the name of the blueprint.  Each key points to another dictionary
+        #: where the key is the status code of the http exception.  The
+        #: special key ``None`` points to a list of tuples where the first item
+        #: is the class for the instance check and the second the error handler
+        #: function.
+        #:
+        #: To register an error handler, use the :meth:`errorhandler`
+        #: decorator.
+        self.error_handler_spec = {}
+
+        #: A list of functions that are called when :meth:`url_for` raises a
+        #: :exc:`~werkzeug.routing.BuildError`.  Each function registered here
+        #: is called with `error`, `endpoint` and `values`.  If a function
+        #: returns ``None`` or raises a :exc:`BuildError` the next function is
+        #: tried.
+        #:
+        #: .. versionadded:: 0.9
+        self.url_build_error_handlers = []
+
+        #: A dictionary with lists of functions that will be called at the
+        #: beginning of each request. The key of the dictionary is the name of
+        #: the blueprint this function is active for, or ``None`` for all
+        #: requests. To register a function, use the :meth:`before_request`
+        #: decorator.
+        self.before_request_funcs = {}
+
+        #: A list of functions that will be called at the beginning of the
+        #: first request to this instance. To register a function, use the
+        #: :meth:`before_first_request` decorator.
+        #:
+        #: .. versionadded:: 0.8
+        self.before_first_request_funcs = []
+
+        #: A dictionary with lists of functions that should be called after
+        #: each request.  The key of the dictionary is the name of the blueprint
+        #: this function is active for, ``None`` for all requests.  This can for
+        #: example be used to close database connections. To register a function
+        #: here, use the :meth:`after_request` decorator.
+        self.after_request_funcs = {}
+
+        #: A dictionary with lists of functions that are called after
+        #: each request, even if an exception has occurred. The key of the
+        #: dictionary is the name of the blueprint this function is active for,
+        #: ``None`` for all requests. These functions are not allowed to modify
+        #: the request, and their return values are ignored. If an exception
+        #: occurred while processing the request, it gets passed to each
+        #: teardown_request function. To register a function here, use the
+        #: :meth:`teardown_request` decorator.
+        #:
+        #: .. versionadded:: 0.7
+        self.teardown_request_funcs = {}
+
+        #: A list of functions that are called when the application context
+        #: is destroyed.  Since the application context is also torn down
+        #: if the request ends this is the place to store code that disconnects
+        #: from databases.
+        #:
+        #: .. versionadded:: 0.9
+        self.teardown_appcontext_funcs = []
+
+        #: A dictionary with lists of functions that are called before the
+        #: :attr:`before_request_funcs` functions. The key of the dictionary is
+        #: the name of the blueprint this function is active for, or ``None``
+        #: for all requests. To register a function, use
+        #: :meth:`url_value_preprocessor`.
+        #:
+        #: .. versionadded:: 0.7
+        self.url_value_preprocessors = {}
+
+        #: A dictionary with lists of functions that can be used as URL value
+        #: preprocessors.  The key ``None`` here is used for application wide
+        #: callbacks, otherwise the key is the name of the blueprint.
+        #: Each of these functions has the chance to modify the dictionary
+        #: of URL values before they are used as the keyword arguments of the
+        #: view function.  For each function registered this one should also
+        #: provide a :meth:`url_defaults` function that adds the parameters
+        #: automatically again that were removed that way.
+        #:
+        #: .. versionadded:: 0.7
+        self.url_default_functions = {}
+
+        #: A dictionary with list of functions that are called without argument
+        #: to populate the template context.  The key of the dictionary is the
+        #: name of the blueprint this function is active for, ``None`` for all
+        #: requests.  Each returns a dictionary that the template context is
+        #: updated with.  To register a function here, use the
+        #: :meth:`context_processor` decorator.
+        self.template_context_processors = {
+            None: [_default_template_ctx_processor]
+        }
+
+        #: A list of shell context processor functions that should be run
+        #: when a shell context is created.
+        #:
+        #: .. versionadded:: 0.11
+        self.shell_context_processors = []
+
+        #: all the attached blueprints in a dictionary by name.  Blueprints
+        #: can be attached multiple times so this dictionary does not tell
+        #: you how often they got attached.
+        #:
+        #: .. versionadded:: 0.7
+        self.blueprints = {}
+        self._blueprint_order = []
+
+        #: a place where extensions can store application specific state.  For
+        #: example this is where an extension could store database engines and
+        #: similar things.  For backwards compatibility extensions should register
+        #: themselves like this::
+        #:
+        #:      if not hasattr(app, 'extensions'):
+        #:          app.extensions = {}
+        #:      app.extensions['extensionname'] = SomeObject()
+        #:
+        #: The key must match the name of the extension module. For example in
+        #: case of a "Flask-Foo" extension in `flask_foo`, the key would be
+        #: ``'foo'``.
+        #:
+        #: .. versionadded:: 0.7
+        self.extensions = {}
+
+        #: The :class:`~werkzeug.routing.Map` for this instance.  You can use
+        #: this to change the routing converters after the class was created
+        #: but before any routes are connected.  Example::
+        #:
+        #:    from werkzeug.routing import BaseConverter
+        #:
+        #:    class ListConverter(BaseConverter):
+        #:        def to_python(self, value):
+        #:            return value.split(',')
+        #:        def to_url(self, values):
+        #:            return ','.join(super(ListConverter, self).to_url(value)
+        #:                            for value in values)
+        #:
+        #:    app = Flask(__name__)
+        #:    app.url_map.converters['list'] = ListConverter
+        self.url_map = Map()
+
+        self.url_map.host_matching = host_matching
+        self.subdomain_matching = subdomain_matching
+
+        # tracks internally if the application already handled at least one
+        # request.
+        self._got_first_request = False
+        self._before_request_lock = Lock()
+
+        # Add a static route using the provided static_url_path, static_host,
+        # and static_folder if there is a configured static_folder.
+        # Note we do this without checking if static_folder exists.
+        # For one, it might be created while the server is running (e.g. during
+        # development). Also, Google App Engine stores static files somewhere
+        if self.has_static_folder:
+            assert bool(static_host) == host_matching, 'Invalid static_host/host_matching combination'
+            self.add_url_rule(
+                self.static_url_path + '/<path:filename>',
+                endpoint='static',
+                host=static_host,
+                view_func=self.send_static_file
+            )
+
+        #: The click command line context for this application.  Commands
+        #: registered here show up in the :command:`flask` command once the
+        #: application has been discovered.  The default commands are
+        #: provided by Flask itself and can be overridden.
+        #:
+        #: This is an instance of a :class:`click.Group` object.
+        self.cli = cli.AppGroup(self.name)
+
+    @locked_cached_property
+    def name(self):
+        """The name of the application.  This is usually the import name
+        with the difference that it's guessed from the run file if the
+        import name is main.  This name is used as a display name when
+        Flask needs the name of the application.  It can be set and overridden
+        to change the value.
+
+        .. versionadded:: 0.8
+        """
+        if self.import_name == '__main__':
+            fn = getattr(sys.modules['__main__'], '__file__', None)
+            if fn is None:
+                return '__main__'
+            return os.path.splitext(os.path.basename(fn))[0]
+        return self.import_name
+
+    @property
+    def propagate_exceptions(self):
+        """Returns the value of the ``PROPAGATE_EXCEPTIONS`` configuration
+        value in case it's set, otherwise a sensible default is returned.
+
+        .. versionadded:: 0.7
+        """
+        rv = self.config['PROPAGATE_EXCEPTIONS']
+        if rv is not None:
+            return rv
+        return self.testing or self.debug
+
+    @property
+    def preserve_context_on_exception(self):
+        """Returns the value of the ``PRESERVE_CONTEXT_ON_EXCEPTION``
+        configuration value in case it's set, otherwise a sensible default
+        is returned.
+
+        .. versionadded:: 0.7
+        """
+        rv = self.config['PRESERVE_CONTEXT_ON_EXCEPTION']
+        if rv is not None:
+            return rv
+        return self.debug
+
+    @locked_cached_property
+    def logger(self):
+        """The ``'flask.app'`` logger, a standard Python
+        :class:`~logging.Logger`.
+
+        In debug mode, the logger's :attr:`~logging.Logger.level` will be set
+        to :data:`~logging.DEBUG`.
+
+        If there are no handlers configured, a default handler will be added.
+        See :ref:`logging` for more information.
+
+        .. versionchanged:: 1.0
+            Behavior was simplified. The logger is always named
+            ``flask.app``. The level is only set during configuration, it
+            doesn't check ``app.debug`` each time. Only one format is used,
+            not different ones depending on ``app.debug``. No handlers are
+            removed, and a handler is only added if no handlers are already
+            configured.
+
+        .. versionadded:: 0.3
+        """
+        return create_logger(self)
+
+    @locked_cached_property
+    def jinja_env(self):
+        """The Jinja2 environment used to load templates."""
+        return self.create_jinja_environment()
+
+    @property
+    def got_first_request(self):
+        """This attribute is set to ``True`` if the application started
+        handling the first request.
+
+        .. versionadded:: 0.8
+        """
+        return self._got_first_request
+
+    def make_config(self, instance_relative=False):
+        """Used to create the config attribute by the Flask constructor.
+        The `instance_relative` parameter is passed in from the constructor
+        of Flask (there named `instance_relative_config`) and indicates if
+        the config should be relative to the instance path or the root path
+        of the application.
+
+        .. versionadded:: 0.8
+        """
+        root_path = self.root_path
+        if instance_relative:
+            root_path = self.instance_path
+        defaults = dict(self.default_config)
+        defaults['ENV'] = get_env()
+        defaults['DEBUG'] = get_debug_flag()
+        return self.config_class(root_path, defaults)
+
+    def auto_find_instance_path(self):
+        """Tries to locate the instance path if it was not provided to the
+        constructor of the application class.  It will basically calculate
+        the path to a folder named ``instance`` next to your main file or
+        the package.
+
+        .. versionadded:: 0.8
+        """
+        prefix, package_path = find_package(self.import_name)
+        if prefix is None:
+            return os.path.join(package_path, 'instance')
+        return os.path.join(prefix, 'var', self.name + '-instance')
+
+    def open_instance_resource(self, resource, mode='rb'):
+        """Opens a resource from the application's instance folder
+        (:attr:`instance_path`).  Otherwise works like
+        :meth:`open_resource`.  Instance resources can also be opened for
+        writing.
+
+        :param resource: the name of the resource.  To access resources within
+                         subfolders use forward slashes as separator.
+        :param mode: resource file opening mode, default is 'rb'.
+        """
+        return open(os.path.join(self.instance_path, resource), mode)
+
+    def _get_templates_auto_reload(self):
+        """Reload templates when they are changed. Used by
+        :meth:`create_jinja_environment`.
+
+        This attribute can be configured with :data:`TEMPLATES_AUTO_RELOAD`. If
+        not set, it will be enabled in debug mode.
+
+        .. versionadded:: 1.0
+            This property was added but the underlying config and behavior
+            already existed.
+        """
+        rv = self.config['TEMPLATES_AUTO_RELOAD']
+        return rv if rv is not None else self.debug
+
+    def _set_templates_auto_reload(self, value):
+        self.config['TEMPLATES_AUTO_RELOAD'] = value
+
+    templates_auto_reload = property(
+        _get_templates_auto_reload, _set_templates_auto_reload
+    )
+    del _get_templates_auto_reload, _set_templates_auto_reload
+
+    def create_jinja_environment(self):
+        """Creates the Jinja2 environment based on :attr:`jinja_options`
+        and :meth:`select_jinja_autoescape`.  Since 0.7 this also adds
+        the Jinja2 globals and filters after initialization.  Override
+        this function to customize the behavior.
+
+        .. versionadded:: 0.5
+        .. versionchanged:: 0.11
+           ``Environment.auto_reload`` set in accordance with
+           ``TEMPLATES_AUTO_RELOAD`` configuration option.
+        """
+        options = dict(self.jinja_options)
+
+        if 'autoescape' not in options:
+            options['autoescape'] = self.select_jinja_autoescape
+
+        if 'auto_reload' not in options:
+            options['auto_reload'] = self.templates_auto_reload
+
+        rv = self.jinja_environment(self, **options)
+        rv.globals.update(
+            url_for=url_for,
+            get_flashed_messages=get_flashed_messages,
+            config=self.config,
+            # request, session and g are normally added with the
+            # context processor for efficiency reasons but for imported
+            # templates we also want the proxies in there.
+            request=request,
+            session=session,
+            g=g
+        )
+        rv.filters['tojson'] = json.tojson_filter
+        return rv
+
+    def create_global_jinja_loader(self):
+        """Creates the loader for the Jinja2 environment.  Can be used to
+        override just the loader and keeping the rest unchanged.  It's
+        discouraged to override this function.  Instead one should override
+        the :meth:`jinja_loader` function instead.
+
+        The global loader dispatches between the loaders of the application
+        and the individual blueprints.
+
+        .. versionadded:: 0.7
+        """
+        return DispatchingJinjaLoader(self)
+
+    def select_jinja_autoescape(self, filename):
+        """Returns ``True`` if autoescaping should be active for the given
+        template name. If no template name is given, returns `True`.
+
+        .. versionadded:: 0.5
+        """
+        if filename is None:
+            return True
+        return filename.endswith(('.html', '.htm', '.xml', '.xhtml'))
+
+    def update_template_context(self, context):
+        """Update the template context with some commonly used variables.
+        This injects request, session, config and g into the template
+        context as well as everything template context processors want
+        to inject.  Note that the as of Flask 0.6, the original values
+        in the context will not be overridden if a context processor
+        decides to return a value with the same key.
+
+        :param context: the context as a dictionary that is updated in place
+                        to add extra variables.
+        """
+        funcs = self.template_context_processors[None]
+        reqctx = _request_ctx_stack.top
+        if reqctx is not None:
+            bp = reqctx.request.blueprint
+            if bp is not None and bp in self.template_context_processors:
+                funcs = chain(funcs, self.template_context_processors[bp])
+        orig_ctx = context.copy()
+        for func in funcs:
+            context.update(func())
+        # make sure the original values win.  This makes it possible to
+        # easier add new variables in context processors without breaking
+        # existing views.
+        context.update(orig_ctx)
+
+    def make_shell_context(self):
+        """Returns the shell context for an interactive shell for this
+        application.  This runs all the registered shell context
+        processors.
+
+        .. versionadded:: 0.11
+        """
+        rv = {'app': self, 'g': g}
+        for processor in self.shell_context_processors:
+            rv.update(processor())
+        return rv
+
+    #: What environment the app is running in. Flask and extensions may
+    #: enable behaviors based on the environment, such as enabling debug
+    #: mode. This maps to the :data:`ENV` config key. This is set by the
+    #: :envvar:`FLASK_ENV` environment variable and may not behave as
+    #: expected if set in code.
+    #:
+    #: **Do not enable development when deploying in production.**
+    #:
+    #: Default: ``'production'``
+    env = ConfigAttribute('ENV')
+
+    def _get_debug(self):
+        return self.config['DEBUG']
+
+    def _set_debug(self, value):
+        self.config['DEBUG'] = value
+        self.jinja_env.auto_reload = self.templates_auto_reload
+
+    #: Whether debug mode is enabled. When using ``flask run`` to start
+    #: the development server, an interactive debugger will be shown for
+    #: unhandled exceptions, and the server will be reloaded when code
+    #: changes. This maps to the :data:`DEBUG` config key. This is
+    #: enabled when :attr:`env` is ``'development'`` and is overridden
+    #: by the ``FLASK_DEBUG`` environment variable. It may not behave as
+    #: expected if set in code.
+    #:
+    #: **Do not enable debug mode when deploying in production.**
+    #:
+    #: Default: ``True`` if :attr:`env` is ``'development'``, or
+    #: ``False`` otherwise.
+    debug = property(_get_debug, _set_debug)
+    del _get_debug, _set_debug
+
+    def run(self, host=None, port=None, debug=None,
+            load_dotenv=True, **options):
+        """Runs the application on a local development server.
+
+        Do not use ``run()`` in a production setting. It is not intended to
+        meet security and performance requirements for a production server.
+        Instead, see :ref:`deployment` for WSGI server recommendations.
+
+        If the :attr:`debug` flag is set the server will automatically reload
+        for code changes and show a debugger in case an exception happened.
+
+        If you want to run the application in debug mode, but disable the
+        code execution on the interactive debugger, you can pass
+        ``use_evalex=False`` as parameter.  This will keep the debugger's
+        traceback screen active, but disable code execution.
+
+        It is not recommended to use this function for development with
+        automatic reloading as this is badly supported.  Instead you should
+        be using the :command:`flask` command line script's ``run`` support.
+
+        .. admonition:: Keep in Mind
+
+           Flask will suppress any server error with a generic error page
+           unless it is in debug mode.  As such to enable just the
+           interactive debugger without the code reloading, you have to
+           invoke :meth:`run` with ``debug=True`` and ``use_reloader=False``.
+           Setting ``use_debugger`` to ``True`` without being in debug mode
+           won't catch any exceptions because there won't be any to
+           catch.
+
+        :param host: the hostname to listen on. Set this to ``'0.0.0.0'`` to
+            have the server available externally as well. Defaults to
+            ``'127.0.0.1'`` or the host in the ``SERVER_NAME`` config variable
+            if present.
+        :param port: the port of the webserver. Defaults to ``5000`` or the
+            port defined in the ``SERVER_NAME`` config variable if present.
+        :param debug: if given, enable or disable debug mode. See
+            :attr:`debug`.
+        :param load_dotenv: Load the nearest :file:`.env` and :file:`.flaskenv`
+            files to set environment variables. Will also change the working
+            directory to the directory containing the first file found.
+        :param options: the options to be forwarded to the underlying Werkzeug
+            server. See :func:`werkzeug.serving.run_simple` for more
+            information.
+
+        .. versionchanged:: 1.0
+            If installed, python-dotenv will be used to load environment
+            variables from :file:`.env` and :file:`.flaskenv` files.
+
+            If set, the :envvar:`FLASK_ENV` and :envvar:`FLASK_DEBUG`
+            environment variables will override :attr:`env` and
+            :attr:`debug`.
+
+            Threaded mode is enabled by default.
+
+        .. versionchanged:: 0.10
+            The default port is now picked from the ``SERVER_NAME``
+            variable.
+        """
+        # Change this into a no-op if the server is invoked from the
+        # command line. Have a look at cli.py for more information.
+        if os.environ.get('FLASK_RUN_FROM_CLI') == 'true':
+            from .debughelpers import explain_ignored_app_run
+            explain_ignored_app_run()
+            return
+
+        if get_load_dotenv(load_dotenv):
+            cli.load_dotenv()
+
+            # if set, let env vars override previous values
+            if 'FLASK_ENV' in os.environ:
+                self.env = get_env()
+                self.debug = get_debug_flag()
+            elif 'FLASK_DEBUG' in os.environ:
+                self.debug = get_debug_flag()
+
+        # debug passed to method overrides all other sources
+        if debug is not None:
+            self.debug = bool(debug)
+
+        _host = '127.0.0.1'
+        _port = 5000
+        server_name = self.config.get('SERVER_NAME')
+        sn_host, sn_port = None, None
+
+        if server_name:
+            sn_host, _, sn_port = server_name.partition(':')
+
+        host = host or sn_host or _host
+        port = int(port or sn_port or _port)
+
+        options.setdefault('use_reloader', self.debug)
+        options.setdefault('use_debugger', self.debug)
+        options.setdefault('threaded', True)
+
+        cli.show_server_banner(self.env, self.debug, self.name, False)
+
+        from werkzeug.serving import run_simple
+
+        try:
+            run_simple(host, port, self, **options)
+        finally:
+            # reset the first request information if the development server
+            # reset normally.  This makes it possible to restart the server
+            # without reloader and that stuff from an interactive shell.
+            self._got_first_request = False
+
+    def test_client(self, use_cookies=True, **kwargs):
+        """Creates a test client for this application.  For information
+        about unit testing head over to :ref:`testing`.
+
+        Note that if you are testing for assertions or exceptions in your
+        application code, you must set ``app.testing = True`` in order for the
+        exceptions to propagate to the test client.  Otherwise, the exception
+        will be handled by the application (not visible to the test client) and
+        the only indication of an AssertionError or other exception will be a
+        500 status code response to the test client.  See the :attr:`testing`
+        attribute.  For example::
+
+            app.testing = True
+            client = app.test_client()
+
+        The test client can be used in a ``with`` block to defer the closing down
+        of the context until the end of the ``with`` block.  This is useful if
+        you want to access the context locals for testing::
+
+            with app.test_client() as c:
+                rv = c.get('/?vodka=42')
+                assert request.args['vodka'] == '42'
+
+        Additionally, you may pass optional keyword arguments that will then
+        be passed to the application's :attr:`test_client_class` constructor.
+        For example::
+
+            from flask.testing import FlaskClient
+
+            class CustomClient(FlaskClient):
+                def __init__(self, *args, **kwargs):
+                    self._authentication = kwargs.pop("authentication")
+                    super(CustomClient,self).__init__( *args, **kwargs)
+
+            app.test_client_class = CustomClient
+            client = app.test_client(authentication='Basic ....')
+
+        See :class:`~flask.testing.FlaskClient` for more information.
+
+        .. versionchanged:: 0.4
+           added support for ``with`` block usage for the client.
+
+        .. versionadded:: 0.7
+           The `use_cookies` parameter was added as well as the ability
+           to override the client to be used by setting the
+           :attr:`test_client_class` attribute.
+
+        .. versionchanged:: 0.11
+           Added `**kwargs` to support passing additional keyword arguments to
+           the constructor of :attr:`test_client_class`.
+        """
+        cls = self.test_client_class
+        if cls is None:
+            from flask.testing import FlaskClient as cls
+        return cls(self, self.response_class, use_cookies=use_cookies, **kwargs)
+
+    def test_cli_runner(self, **kwargs):
+        """Create a CLI runner for testing CLI commands.
+        See :ref:`testing-cli`.
+
+        Returns an instance of :attr:`test_cli_runner_class`, by default
+        :class:`~flask.testing.FlaskCliRunner`. The Flask app object is
+        passed as the first argument.
+
+        .. versionadded:: 1.0
+        """
+        cls = self.test_cli_runner_class
+
+        if cls is None:
+            from flask.testing import FlaskCliRunner as cls
+
+        return cls(self, **kwargs)
+
+    def open_session(self, request):
+        """Creates or opens a new session.  Default implementation stores all
+        session data in a signed cookie.  This requires that the
+        :attr:`secret_key` is set.  Instead of overriding this method
+        we recommend replacing the :class:`session_interface`.
+
+        .. deprecated: 1.0
+            Will be removed in 1.1. Use ``session_interface.open_session``
+            instead.
+
+        :param request: an instance of :attr:`request_class`.
+        """
+
+        warnings.warn(DeprecationWarning(
+            '"open_session" is deprecated and will be removed in 1.1. Use'
+            ' "session_interface.open_session" instead.'
+        ))
+        return self.session_interface.open_session(self, request)
+
+    def save_session(self, session, response):
+        """Saves the session if it needs updates.  For the default
+        implementation, check :meth:`open_session`.  Instead of overriding this
+        method we recommend replacing the :class:`session_interface`.
+
+        .. deprecated: 1.0
+            Will be removed in 1.1. Use ``session_interface.save_session``
+            instead.
+
+        :param session: the session to be saved (a
+                        :class:`~werkzeug.contrib.securecookie.SecureCookie`
+                        object)
+        :param response: an instance of :attr:`response_class`
+        """
+
+        warnings.warn(DeprecationWarning(
+            '"save_session" is deprecated and will be removed in 1.1. Use'
+            ' "session_interface.save_session" instead.'
+        ))
+        return self.session_interface.save_session(self, session, response)
+
+    def make_null_session(self):
+        """Creates a new instance of a missing session.  Instead of overriding
+        this method we recommend replacing the :class:`session_interface`.
+
+        .. deprecated: 1.0
+            Will be removed in 1.1. Use ``session_interface.make_null_session``
+            instead.
+
+        .. versionadded:: 0.7
+        """
+
+        warnings.warn(DeprecationWarning(
+            '"make_null_session" is deprecated and will be removed in 1.1. Use'
+            ' "session_interface.make_null_session" instead.'
+        ))
+        return self.session_interface.make_null_session(self)
+
+    @setupmethod
+    def register_blueprint(self, blueprint, **options):
+        """Register a :class:`~flask.Blueprint` on the application. Keyword
+        arguments passed to this method will override the defaults set on the
+        blueprint.
+
+        Calls the blueprint's :meth:`~flask.Blueprint.register` method after
+        recording the blueprint in the application's :attr:`blueprints`.
+
+        :param blueprint: The blueprint to register.
+        :param url_prefix: Blueprint routes will be prefixed with this.
+        :param subdomain: Blueprint routes will match on this subdomain.
+        :param url_defaults: Blueprint routes will use these default values for
+            view arguments.
+        :param options: Additional keyword arguments are passed to
+            :class:`~flask.blueprints.BlueprintSetupState`. They can be
+            accessed in :meth:`~flask.Blueprint.record` callbacks.
+
+        .. versionadded:: 0.7
+        """
+        first_registration = False
+
+        if blueprint.name in self.blueprints:
+            assert self.blueprints[blueprint.name] is blueprint, (
+                'A name collision occurred between blueprints %r and %r. Both'
+                ' share the same name "%s". Blueprints that are created on the'
+                ' fly need unique names.' % (
+                    blueprint, self.blueprints[blueprint.name], blueprint.name
+                )
+            )
+        else:
+            self.blueprints[blueprint.name] = blueprint
+            self._blueprint_order.append(blueprint)
+            first_registration = True
+
+        blueprint.register(self, options, first_registration)
+
+    def iter_blueprints(self):
+        """Iterates over all blueprints by the order they were registered.
+
+        .. versionadded:: 0.11
+        """
+        return iter(self._blueprint_order)
+
+    @setupmethod
+    def add_url_rule(self, rule, endpoint=None, view_func=None,
+                     provide_automatic_options=None, **options):
+        """Connects a URL rule.  Works exactly like the :meth:`route`
+        decorator.  If a view_func is provided it will be registered with the
+        endpoint.
+
+        Basically this example::
+
+            @app.route('/')
+            def index():
+                pass
+
+        Is equivalent to the following::
+
+            def index():
+                pass
+            app.add_url_rule('/', 'index', index)
+
+        If the view_func is not provided you will need to connect the endpoint
+        to a view function like so::
+
+            app.view_functions['index'] = index
+
+        Internally :meth:`route` invokes :meth:`add_url_rule` so if you want
+        to customize the behavior via subclassing you only need to change
+        this method.
+
+        For more information refer to :ref:`url-route-registrations`.
+
+        .. versionchanged:: 0.2
+           `view_func` parameter added.
+
+        .. versionchanged:: 0.6
+           ``OPTIONS`` is added automatically as method.
+
+        :param rule: the URL rule as string
+        :param endpoint: the endpoint for the registered URL rule.  Flask
+                         itself assumes the name of the view function as
+                         endpoint
+        :param view_func: the function to call when serving a request to the
+                          provided endpoint
+        :param provide_automatic_options: controls whether the ``OPTIONS``
+            method should be added automatically. This can also be controlled
+            by setting the ``view_func.provide_automatic_options = False``
+            before adding the rule.
+        :param options: the options to be forwarded to the underlying
+                        :class:`~werkzeug.routing.Rule` object.  A change
+                        to Werkzeug is handling of method options.  methods
+                        is a list of methods this rule should be limited
+                        to (``GET``, ``POST`` etc.).  By default a rule
+                        just listens for ``GET`` (and implicitly ``HEAD``).
+                        Starting with Flask 0.6, ``OPTIONS`` is implicitly
+                        added and handled by the standard request handling.
+        """
+        if endpoint is None:
+            endpoint = _endpoint_from_view_func(view_func)
+        options['endpoint'] = endpoint
+        methods = options.pop('methods', None)
+
+        # if the methods are not given and the view_func object knows its
+        # methods we can use that instead.  If neither exists, we go with
+        # a tuple of only ``GET`` as default.
+        if methods is None:
+            methods = getattr(view_func, 'methods', None) or ('GET',)
+        if isinstance(methods, string_types):
+            raise TypeError('Allowed methods have to be iterables of strings, '
+                            'for example: @app.route(..., methods=["POST"])')
+        methods = set(item.upper() for item in methods)
+
+        # Methods that should always be added
+        required_methods = set(getattr(view_func, 'required_methods', ()))
+
+        # starting with Flask 0.8 the view_func object can disable and
+        # force-enable the automatic options handling.
+        if provide_automatic_options is None:
+            provide_automatic_options = getattr(view_func,
+                'provide_automatic_options', None)
+
+        if provide_automatic_options is None:
+            if 'OPTIONS' not in methods:
+                provide_automatic_options = True
+                required_methods.add('OPTIONS')
+            else:
+                provide_automatic_options = False
+
+        # Add the required methods now.
+        methods |= required_methods
+
+        rule = self.url_rule_class(rule, methods=methods, **options)
+        rule.provide_automatic_options = provide_automatic_options
+
+        self.url_map.add(rule)
+        if view_func is not None:
+            old_func = self.view_functions.get(endpoint)
+            if old_func is not None and old_func != view_func:
+                raise AssertionError('View function mapping is overwriting an '
+                                     'existing endpoint function: %s' % endpoint)
+            self.view_functions[endpoint] = view_func
+
+    def route(self, rule, **options):
+        """A decorator that is used to register a view function for a
+        given URL rule.  This does the same thing as :meth:`add_url_rule`
+        but is intended for decorator usage::
+
+            @app.route('/')
+            def index():
+                return 'Hello World'
+
+        For more information refer to :ref:`url-route-registrations`.
+
+        :param rule: the URL rule as string
+        :param endpoint: the endpoint for the registered URL rule.  Flask
+                         itself assumes the name of the view function as
+                         endpoint
+        :param options: the options to be forwarded to the underlying
+                        :class:`~werkzeug.routing.Rule` object.  A change
+                        to Werkzeug is handling of method options.  methods
+                        is a list of methods this rule should be limited
+                        to (``GET``, ``POST`` etc.).  By default a rule
+                        just listens for ``GET`` (and implicitly ``HEAD``).
+                        Starting with Flask 0.6, ``OPTIONS`` is implicitly
+                        added and handled by the standard request handling.
+        """
+        def decorator(f):
+            endpoint = options.pop('endpoint', None)
+            self.add_url_rule(rule, endpoint, f, **options)
+            return f
+        return decorator
+
+    @setupmethod
+    def endpoint(self, endpoint):
+        """A decorator to register a function as an endpoint.
+        Example::
+
+            @app.endpoint('example.endpoint')
+            def example():
+                return "example"
+
+        :param endpoint: the name of the endpoint
+        """
+        def decorator(f):
+            self.view_functions[endpoint] = f
+            return f
+        return decorator
+
+    @staticmethod
+    def _get_exc_class_and_code(exc_class_or_code):
+        """Ensure that we register only exceptions as handler keys"""
+        if isinstance(exc_class_or_code, integer_types):
+            exc_class = default_exceptions[exc_class_or_code]
+        else:
+            exc_class = exc_class_or_code
+
+        assert issubclass(exc_class, Exception)
+
+        if issubclass(exc_class, HTTPException):
+            return exc_class, exc_class.code
+        else:
+            return exc_class, None
+
+    @setupmethod
+    def errorhandler(self, code_or_exception):
+        """Register a function to handle errors by code or exception class.
+
+        A decorator that is used to register a function given an
+        error code.  Example::
+
+            @app.errorhandler(404)
+            def page_not_found(error):
+                return 'This page does not exist', 404
+
+        You can also register handlers for arbitrary exceptions::
+
+            @app.errorhandler(DatabaseError)
+            def special_exception_handler(error):
+                return 'Database connection failed', 500
+
+        .. versionadded:: 0.7
+            Use :meth:`register_error_handler` instead of modifying
+            :attr:`error_handler_spec` directly, for application wide error
+            handlers.
+
+        .. versionadded:: 0.7
+           One can now additionally also register custom exception types
+           that do not necessarily have to be a subclass of the
+           :class:`~werkzeug.exceptions.HTTPException` class.
+
+        :param code_or_exception: the code as integer for the handler, or
+                                  an arbitrary exception
+        """
+        def decorator(f):
+            self._register_error_handler(None, code_or_exception, f)
+            return f
+        return decorator
+
+    @setupmethod
+    def register_error_handler(self, code_or_exception, f):
+        """Alternative error attach function to the :meth:`errorhandler`
+        decorator that is more straightforward to use for non decorator
+        usage.
+
+        .. versionadded:: 0.7
+        """
+        self._register_error_handler(None, code_or_exception, f)
+
+    @setupmethod
+    def _register_error_handler(self, key, code_or_exception, f):
+        """
+        :type key: None|str
+        :type code_or_exception: int|T<=Exception
+        :type f: callable
+        """
+        if isinstance(code_or_exception, HTTPException):  # old broken behavior
+            raise ValueError(
+                'Tried to register a handler for an exception instance {0!r}.'
+                ' Handlers can only be registered for exception classes or'
+                ' HTTP error codes.'.format(code_or_exception)
+            )
+
+        try:
+            exc_class, code = self._get_exc_class_and_code(code_or_exception)
+        except KeyError:
+            raise KeyError(
+                "'{0}' is not a recognized HTTP error code. Use a subclass of"
+                " HTTPException with that code instead.".format(code_or_exception)
+            )
+
+        handlers = self.error_handler_spec.setdefault(key, {}).setdefault(code, {})
+        handlers[exc_class] = f
+
+    @setupmethod
+    def template_filter(self, name=None):
+        """A decorator that is used to register custom template filter.
+        You can specify a name for the filter, otherwise the function
+        name will be used. Example::
+
+          @app.template_filter()
+          def reverse(s):
+              return s[::-1]
+
+        :param name: the optional name of the filter, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_template_filter(f, name=name)
+            return f
+        return decorator
+
+    @setupmethod
+    def add_template_filter(self, f, name=None):
+        """Register a custom template filter.  Works exactly like the
+        :meth:`template_filter` decorator.
+
+        :param name: the optional name of the filter, otherwise the
+                     function name will be used.
+        """
+        self.jinja_env.filters[name or f.__name__] = f
+
+    @setupmethod
+    def template_test(self, name=None):
+        """A decorator that is used to register custom template test.
+        You can specify a name for the test, otherwise the function
+        name will be used. Example::
+
+          @app.template_test()
+          def is_prime(n):
+              if n == 2:
+                  return True
+              for i in range(2, int(math.ceil(math.sqrt(n))) + 1):
+                  if n % i == 0:
+                      return False
+              return True
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the test, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_template_test(f, name=name)
+            return f
+        return decorator
+
+    @setupmethod
+    def add_template_test(self, f, name=None):
+        """Register a custom template test.  Works exactly like the
+        :meth:`template_test` decorator.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the test, otherwise the
+                     function name will be used.
+        """
+        self.jinja_env.tests[name or f.__name__] = f
+
+    @setupmethod
+    def template_global(self, name=None):
+        """A decorator that is used to register a custom template global function.
+        You can specify a name for the global function, otherwise the function
+        name will be used. Example::
+
+            @app.template_global()
+            def double(n):
+                return 2 * n
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the global function, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_template_global(f, name=name)
+            return f
+        return decorator
+
+    @setupmethod
+    def add_template_global(self, f, name=None):
+        """Register a custom template global function. Works exactly like the
+        :meth:`template_global` decorator.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the global function, otherwise the
+                     function name will be used.
+        """
+        self.jinja_env.globals[name or f.__name__] = f
+
+    @setupmethod
+    def before_request(self, f):
+        """Registers a function to run before each request.
+
+        For example, this can be used to open a database connection, or to load
+        the logged in user from the session.
+
+        The function will be called without any arguments. If it returns a
+        non-None value, the value is handled as if it was the return value from
+        the view, and further request handling is stopped.
+        """
+        self.before_request_funcs.setdefault(None, []).append(f)
+        return f
+
+    @setupmethod
+    def before_first_request(self, f):
+        """Registers a function to be run before the first request to this
+        instance of the application.
+
+        The function will be called without any arguments and its return
+        value is ignored.
+
+        .. versionadded:: 0.8
+        """
+        self.before_first_request_funcs.append(f)
+        return f
+
+    @setupmethod
+    def after_request(self, f):
+        """Register a function to be run after each request.
+
+        Your function must take one parameter, an instance of
+        :attr:`response_class` and return a new response object or the
+        same (see :meth:`process_response`).
+
+        As of Flask 0.7 this function might not be executed at the end of the
+        request in case an unhandled exception occurred.
+        """
+        self.after_request_funcs.setdefault(None, []).append(f)
+        return f
+
+    @setupmethod
+    def teardown_request(self, f):
+        """Register a function to be run at the end of each request,
+        regardless of whether there was an exception or not.  These functions
+        are executed when the request context is popped, even if not an
+        actual request was performed.
+
+        Example::
+
+            ctx = app.test_request_context()
+            ctx.push()
+            ...
+            ctx.pop()
+
+        When ``ctx.pop()`` is executed in the above example, the teardown
+        functions are called just before the request context moves from the
+        stack of active contexts.  This becomes relevant if you are using
+        such constructs in tests.
+
+        Generally teardown functions must take every necessary step to avoid
+        that they will fail.  If they do execute code that might fail they
+        will have to surround the execution of these code by try/except
+        statements and log occurring errors.
+
+        When a teardown function was called because of an exception it will
+        be passed an error object.
+
+        The return values of teardown functions are ignored.
+
+        .. admonition:: Debug Note
+
+           In debug mode Flask will not tear down a request on an exception
+           immediately.  Instead it will keep it alive so that the interactive
+           debugger can still access it.  This behavior can be controlled
+           by the ``PRESERVE_CONTEXT_ON_EXCEPTION`` configuration variable.
+        """
+        self.teardown_request_funcs.setdefault(None, []).append(f)
+        return f
+
+    @setupmethod
+    def teardown_appcontext(self, f):
+        """Registers a function to be called when the application context
+        ends.  These functions are typically also called when the request
+        context is popped.
+
+        Example::
+
+            ctx = app.app_context()
+            ctx.push()
+            ...
+            ctx.pop()
+
+        When ``ctx.pop()`` is executed in the above example, the teardown
+        functions are called just before the app context moves from the
+        stack of active contexts.  This becomes relevant if you are using
+        such constructs in tests.
+
+        Since a request context typically also manages an application
+        context it would also be called when you pop a request context.
+
+        When a teardown function was called because of an unhandled exception
+        it will be passed an error object. If an :meth:`errorhandler` is
+        registered, it will handle the exception and the teardown will not
+        receive it.
+
+        The return values of teardown functions are ignored.
+
+        .. versionadded:: 0.9
+        """
+        self.teardown_appcontext_funcs.append(f)
+        return f
+
+    @setupmethod
+    def context_processor(self, f):
+        """Registers a template context processor function."""
+        self.template_context_processors[None].append(f)
+        return f
+
+    @setupmethod
+    def shell_context_processor(self, f):
+        """Registers a shell context processor function.
+
+        .. versionadded:: 0.11
+        """
+        self.shell_context_processors.append(f)
+        return f
+
+    @setupmethod
+    def url_value_preprocessor(self, f):
+        """Register a URL value preprocessor function for all view
+        functions in the application. These functions will be called before the
+        :meth:`before_request` functions.
+
+        The function can modify the values captured from the matched url before
+        they are passed to the view. For example, this can be used to pop a
+        common language code value and place it in ``g`` rather than pass it to
+        every view.
+
+        The function is passed the endpoint name and values dict. The return
+        value is ignored.
+        """
+        self.url_value_preprocessors.setdefault(None, []).append(f)
+        return f
+
+    @setupmethod
+    def url_defaults(self, f):
+        """Callback function for URL defaults for all view functions of the
+        application.  It's called with the endpoint and values and should
+        update the values passed in place.
+        """
+        self.url_default_functions.setdefault(None, []).append(f)
+        return f
+
+    def _find_error_handler(self, e):
+        """Return a registered error handler for an exception in this order:
+        blueprint handler for a specific code, app handler for a specific code,
+        blueprint handler for an exception class, app handler for an exception
+        class, or ``None`` if a suitable handler is not found.
+        """
+        exc_class, code = self._get_exc_class_and_code(type(e))
+
+        for name, c in (
+            (request.blueprint, code), (None, code),
+            (request.blueprint, None), (None, None)
+        ):
+            handler_map = self.error_handler_spec.setdefault(name, {}).get(c)
+
+            if not handler_map:
+                continue
+
+            for cls in exc_class.__mro__:
+                handler = handler_map.get(cls)
+
+                if handler is not None:
+                    return handler
+
+    def handle_http_exception(self, e):
+        """Handles an HTTP exception.  By default this will invoke the
+        registered error handlers and fall back to returning the
+        exception as response.
+
+        .. versionchanged:: 1.0.3
+            ``RoutingException``, used internally for actions such as
+             slash redirects during routing, is not passed to error
+             handlers.
+
+        .. versionchanged:: 1.0
+            Exceptions are looked up by code *and* by MRO, so
+            ``HTTPExcpetion`` subclasses can be handled with a catch-all
+            handler for the base ``HTTPException``.
+
+        .. versionadded:: 0.3
+        """
+        # Proxy exceptions don't have error codes.  We want to always return
+        # those unchanged as errors
+        if e.code is None:
+            return e
+
+        # RoutingExceptions are used internally to trigger routing
+        # actions, such as slash redirects raising RequestRedirect. They
+        # are not raised or handled in user code.
+        if isinstance(e, RoutingException):
+            return e
+
+        handler = self._find_error_handler(e)
+        if handler is None:
+            return e
+        return handler(e)
+
+    def trap_http_exception(self, e):
+        """Checks if an HTTP exception should be trapped or not.  By default
+        this will return ``False`` for all exceptions except for a bad request
+        key error if ``TRAP_BAD_REQUEST_ERRORS`` is set to ``True``.  It
+        also returns ``True`` if ``TRAP_HTTP_EXCEPTIONS`` is set to ``True``.
+
+        This is called for all HTTP exceptions raised by a view function.
+        If it returns ``True`` for any exception the error handler for this
+        exception is not called and it shows up as regular exception in the
+        traceback.  This is helpful for debugging implicitly raised HTTP
+        exceptions.
+
+        .. versionchanged:: 1.0
+            Bad request errors are not trapped by default in debug mode.
+
+        .. versionadded:: 0.8
+        """
+        if self.config['TRAP_HTTP_EXCEPTIONS']:
+            return True
+
+        trap_bad_request = self.config['TRAP_BAD_REQUEST_ERRORS']
+
+        # if unset, trap key errors in debug mode
+        if (
+            trap_bad_request is None and self.debug
+            and isinstance(e, BadRequestKeyError)
+        ):
+            return True
+
+        if trap_bad_request:
+            return isinstance(e, BadRequest)
+
+        return False
+
+    def handle_user_exception(self, e):
+        """This method is called whenever an exception occurs that
+        should be handled. A special case is :class:`~werkzeug
+        .exceptions.HTTPException` which is forwarded to the
+        :meth:`handle_http_exception` method. This function will either
+        return a response value or reraise the exception with the same
+        traceback.
+
+        .. versionchanged:: 1.0
+            Key errors raised from request data like ``form`` show the
+            bad key in debug mode rather than a generic bad request
+            message.
+
+        .. versionadded:: 0.7
+        """
+        exc_type, exc_value, tb = sys.exc_info()
+        assert exc_value is e
+        # ensure not to trash sys.exc_info() at that point in case someone
+        # wants the traceback preserved in handle_http_exception.  Of course
+        # we cannot prevent users from trashing it themselves in a custom
+        # trap_http_exception method so that's their fault then.
+
+        if isinstance(e, BadRequestKeyError):
+            if self.debug or self.config["TRAP_BAD_REQUEST_ERRORS"]:
+                # Werkzeug < 0.15 doesn't add the KeyError to the 400
+                # message, add it in manually.
+                description = e.get_description()
+
+                if e.args[0] not in description:
+                    e.description = "KeyError: '{}'".format(*e.args)
+            else:
+                # Werkzeug >= 0.15 does add it, remove it in production
+                e.args = ()
+
+        if isinstance(e, HTTPException) and not self.trap_http_exception(e):
+            return self.handle_http_exception(e)
+
+        handler = self._find_error_handler(e)
+
+        if handler is None:
+            reraise(exc_type, exc_value, tb)
+        return handler(e)
+
+    def handle_exception(self, e):
+        """Default exception handling that kicks in when an exception
+        occurs that is not caught.  In debug mode the exception will
+        be re-raised immediately, otherwise it is logged and the handler
+        for a 500 internal server error is used.  If no such handler
+        exists, a default 500 internal server error message is displayed.
+
+        .. versionadded:: 0.3
+        """
+        exc_type, exc_value, tb = sys.exc_info()
+
+        got_request_exception.send(self, exception=e)
+        handler = self._find_error_handler(InternalServerError())
+
+        if self.propagate_exceptions:
+            # if we want to repropagate the exception, we can attempt to
+            # raise it with the whole traceback in case we can do that
+            # (the function was actually called from the except part)
+            # otherwise, we just raise the error again
+            if exc_value is e:
+                reraise(exc_type, exc_value, tb)
+            else:
+                raise e
+
+        self.log_exception((exc_type, exc_value, tb))
+        if handler is None:
+            return InternalServerError()
+        return self.finalize_request(handler(e), from_error_handler=True)
+
+    def log_exception(self, exc_info):
+        """Logs an exception.  This is called by :meth:`handle_exception`
+        if debugging is disabled and right before the handler is called.
+        The default implementation logs the exception as error on the
+        :attr:`logger`.
+
+        .. versionadded:: 0.8
+        """
+        self.logger.error('Exception on %s [%s]' % (
+            request.path,
+            request.method
+        ), exc_info=exc_info)
+
+    def raise_routing_exception(self, request):
+        """Exceptions that are recording during routing are reraised with
+        this method.  During debug we are not reraising redirect requests
+        for non ``GET``, ``HEAD``, or ``OPTIONS`` requests and we're raising
+        a different error instead to help debug situations.
+
+        :internal:
+        """
+        if not self.debug \
+           or not isinstance(request.routing_exception, RequestRedirect) \
+           or request.method in ('GET', 'HEAD', 'OPTIONS'):
+            raise request.routing_exception
+
+        from .debughelpers import FormDataRoutingRedirect
+        raise FormDataRoutingRedirect(request)
+
+    def dispatch_request(self):
+        """Does the request dispatching.  Matches the URL and returns the
+        return value of the view or error handler.  This does not have to
+        be a response object.  In order to convert the return value to a
+        proper response object, call :func:`make_response`.
+
+        .. versionchanged:: 0.7
+           This no longer does the exception handling, this code was
+           moved to the new :meth:`full_dispatch_request`.
+        """
+        req = _request_ctx_stack.top.request
+        if req.routing_exception is not None:
+            self.raise_routing_exception(req)
+        rule = req.url_rule
+        # if we provide automatic options for this URL and the
+        # request came with the OPTIONS method, reply automatically
+        if getattr(rule, 'provide_automatic_options', False) \
+           and req.method == 'OPTIONS':
+            return self.make_default_options_response()
+        # otherwise dispatch to the handler for that endpoint
+        return self.view_functions[rule.endpoint](**req.view_args)
+
+    def full_dispatch_request(self):
+        """Dispatches the request and on top of that performs request
+        pre and postprocessing as well as HTTP exception catching and
+        error handling.
+
+        .. versionadded:: 0.7
+        """
+        self.try_trigger_before_first_request_functions()
+        try:
+            request_started.send(self)
+            rv = self.preprocess_request()
+            if rv is None:
+                rv = self.dispatch_request()
+        except Exception as e:
+            rv = self.handle_user_exception(e)
+        return self.finalize_request(rv)
+
+    def finalize_request(self, rv, from_error_handler=False):
+        """Given the return value from a view function this finalizes
+        the request by converting it into a response and invoking the
+        postprocessing functions.  This is invoked for both normal
+        request dispatching as well as error handlers.
+
+        Because this means that it might be called as a result of a
+        failure a special safe mode is available which can be enabled
+        with the `from_error_handler` flag.  If enabled, failures in
+        response processing will be logged and otherwise ignored.
+
+        :internal:
+        """
+        response = self.make_response(rv)
+        try:
+            response = self.process_response(response)
+            request_finished.send(self, response=response)
+        except Exception:
+            if not from_error_handler:
+                raise
+            self.logger.exception('Request finalizing failed with an '
+                                  'error while handling an error')
+        return response
+
+    def try_trigger_before_first_request_functions(self):
+        """Called before each request and will ensure that it triggers
+        the :attr:`before_first_request_funcs` and only exactly once per
+        application instance (which means process usually).
+
+        :internal:
+        """
+        if self._got_first_request:
+            return
+        with self._before_request_lock:
+            if self._got_first_request:
+                return
+            for func in self.before_first_request_funcs:
+                func()
+            self._got_first_request = True
+
+    def make_default_options_response(self):
+        """This method is called to create the default ``OPTIONS`` response.
+        This can be changed through subclassing to change the default
+        behavior of ``OPTIONS`` responses.
+
+        .. versionadded:: 0.7
+        """
+        adapter = _request_ctx_stack.top.url_adapter
+        if hasattr(adapter, 'allowed_methods'):
+            methods = adapter.allowed_methods()
+        else:
+            # fallback for Werkzeug < 0.7
+            methods = []
+            try:
+                adapter.match(method='--')
+            except MethodNotAllowed as e:
+                methods = e.valid_methods
+            except HTTPException as e:
+                pass
+        rv = self.response_class()
+        rv.allow.update(methods)
+        return rv
+
+    def should_ignore_error(self, error):
+        """This is called to figure out if an error should be ignored
+        or not as far as the teardown system is concerned.  If this
+        function returns ``True`` then the teardown handlers will not be
+        passed the error.
+
+        .. versionadded:: 0.10
+        """
+        return False
+
+    def make_response(self, rv):
+        """Convert the return value from a view function to an instance of
+        :attr:`response_class`.
+
+        :param rv: the return value from the view function. The view function
+            must return a response. Returning ``None``, or the view ending
+            without returning, is not allowed. The following types are allowed
+            for ``view_rv``:
+
+            ``str`` (``unicode`` in Python 2)
+                A response object is created with the string encoded to UTF-8
+                as the body.
+
+            ``bytes`` (``str`` in Python 2)
+                A response object is created with the bytes as the body.
+
+            ``tuple``
+                Either ``(body, status, headers)``, ``(body, status)``, or
+                ``(body, headers)``, where ``body`` is any of the other types
+                allowed here, ``status`` is a string or an integer, and
+                ``headers`` is a dictionary or a list of ``(key, value)``
+                tuples. If ``body`` is a :attr:`response_class` instance,
+                ``status`` overwrites the exiting value and ``headers`` are
+                extended.
+
+            :attr:`response_class`
+                The object is returned unchanged.
+
+            other :class:`~werkzeug.wrappers.Response` class
+                The object is coerced to :attr:`response_class`.
+
+            :func:`callable`
+                The function is called as a WSGI application. The result is
+                used to create a response object.
+
+        .. versionchanged:: 0.9
+           Previously a tuple was interpreted as the arguments for the
+           response object.
+        """
+
+        status = headers = None
+
+        # unpack tuple returns
+        if isinstance(rv, tuple):
+            len_rv = len(rv)
+
+            # a 3-tuple is unpacked directly
+            if len_rv == 3:
+                rv, status, headers = rv
+            # decide if a 2-tuple has status or headers
+            elif len_rv == 2:
+                if isinstance(rv[1], (Headers, dict, tuple, list)):
+                    rv, headers = rv
+                else:
+                    rv, status = rv
+            # other sized tuples are not allowed
+            else:
+                raise TypeError(
+                    'The view function did not return a valid response tuple.'
+                    ' The tuple must have the form (body, status, headers),'
+                    ' (body, status), or (body, headers).'
+                )
+
+        # the body must not be None
+        if rv is None:
+            raise TypeError(
+                'The view function did not return a valid response. The'
+                ' function either returned None or ended without a return'
+                ' statement.'
+            )
+
+        # make sure the body is an instance of the response class
+        if not isinstance(rv, self.response_class):
+            if isinstance(rv, (text_type, bytes, bytearray)):
+                # let the response class set the status and headers instead of
+                # waiting to do it manually, so that the class can handle any
+                # special logic
+                rv = self.response_class(rv, status=status, headers=headers)
+                status = headers = None
+            else:
+                # evaluate a WSGI callable, or coerce a different response
+                # class to the correct type
+                try:
+                    rv = self.response_class.force_type(rv, request.environ)
+                except TypeError as e:
+                    new_error = TypeError(
+                        '{e}\nThe view function did not return a valid'
+                        ' response. The return type must be a string, tuple,'
+                        ' Response instance, or WSGI callable, but it was a'
+                        ' {rv.__class__.__name__}.'.format(e=e, rv=rv)
+                    )
+                    reraise(TypeError, new_error, sys.exc_info()[2])
+
+        # prefer the status if it was provided
+        if status is not None:
+            if isinstance(status, (text_type, bytes, bytearray)):
+                rv.status = status
+            else:
+                rv.status_code = status
+
+        # extend existing headers with provided headers
+        if headers:
+            rv.headers.extend(headers)
+
+        return rv
+
+    def create_url_adapter(self, request):
+        """Creates a URL adapter for the given request. The URL adapter
+        is created at a point where the request context is not yet set
+        up so the request is passed explicitly.
+
+        .. versionadded:: 0.6
+
+        .. versionchanged:: 0.9
+           This can now also be called without a request object when the
+           URL adapter is created for the application context.
+
+        .. versionchanged:: 1.0
+            :data:`SERVER_NAME` no longer implicitly enables subdomain
+            matching. Use :attr:`subdomain_matching` instead.
+        """
+        if request is not None:
+            # If subdomain matching is disabled (the default), use the
+            # default subdomain in all cases. This should be the default
+            # in Werkzeug but it currently does not have that feature.
+            subdomain = ((self.url_map.default_subdomain or None)
+                         if not self.subdomain_matching else None)
+            return self.url_map.bind_to_environ(
+                request.environ,
+                server_name=self.config['SERVER_NAME'],
+                subdomain=subdomain)
+        # We need at the very least the server name to be set for this
+        # to work.
+        if self.config['SERVER_NAME'] is not None:
+            return self.url_map.bind(
+                self.config['SERVER_NAME'],
+                script_name=self.config['APPLICATION_ROOT'],
+                url_scheme=self.config['PREFERRED_URL_SCHEME'])
+
+    def inject_url_defaults(self, endpoint, values):
+        """Injects the URL defaults for the given endpoint directly into
+        the values dictionary passed.  This is used internally and
+        automatically called on URL building.
+
+        .. versionadded:: 0.7
+        """
+        funcs = self.url_default_functions.get(None, ())
+        if '.' in endpoint:
+            bp = endpoint.rsplit('.', 1)[0]
+            funcs = chain(funcs, self.url_default_functions.get(bp, ()))
+        for func in funcs:
+            func(endpoint, values)
+
+    def handle_url_build_error(self, error, endpoint, values):
+        """Handle :class:`~werkzeug.routing.BuildError` on :meth:`url_for`.
+        """
+        exc_type, exc_value, tb = sys.exc_info()
+        for handler in self.url_build_error_handlers:
+            try:
+                rv = handler(error, endpoint, values)
+                if rv is not None:
+                    return rv
+            except BuildError as e:
+                # make error available outside except block (py3)
+                error = e
+
+        # At this point we want to reraise the exception.  If the error is
+        # still the same one we can reraise it with the original traceback,
+        # otherwise we raise it from here.
+        if error is exc_value:
+            reraise(exc_type, exc_value, tb)
+        raise error
+
+    def preprocess_request(self):
+        """Called before the request is dispatched. Calls
+        :attr:`url_value_preprocessors` registered with the app and the
+        current blueprint (if any). Then calls :attr:`before_request_funcs`
+        registered with the app and the blueprint.
+
+        If any :meth:`before_request` handler returns a non-None value, the
+        value is handled as if it was the return value from the view, and
+        further request handling is stopped.
+        """
+
+        bp = _request_ctx_stack.top.request.blueprint
+
+        funcs = self.url_value_preprocessors.get(None, ())
+        if bp is not None and bp in self.url_value_preprocessors:
+            funcs = chain(funcs, self.url_value_preprocessors[bp])
+        for func in funcs:
+            func(request.endpoint, request.view_args)
+
+        funcs = self.before_request_funcs.get(None, ())
+        if bp is not None and bp in self.before_request_funcs:
+            funcs = chain(funcs, self.before_request_funcs[bp])
+        for func in funcs:
+            rv = func()
+            if rv is not None:
+                return rv
+
+    def process_response(self, response):
+        """Can be overridden in order to modify the response object
+        before it's sent to the WSGI server.  By default this will
+        call all the :meth:`after_request` decorated functions.
+
+        .. versionchanged:: 0.5
+           As of Flask 0.5 the functions registered for after request
+           execution are called in reverse order of registration.
+
+        :param response: a :attr:`response_class` object.
+        :return: a new response object or the same, has to be an
+                 instance of :attr:`response_class`.
+        """
+        ctx = _request_ctx_stack.top
+        bp = ctx.request.blueprint
+        funcs = ctx._after_request_functions
+        if bp is not None and bp in self.after_request_funcs:
+            funcs = chain(funcs, reversed(self.after_request_funcs[bp]))
+        if None in self.after_request_funcs:
+            funcs = chain(funcs, reversed(self.after_request_funcs[None]))
+        for handler in funcs:
+            response = handler(response)
+        if not self.session_interface.is_null_session(ctx.session):
+            self.session_interface.save_session(self, ctx.session, response)
+        return response
+
+    def do_teardown_request(self, exc=_sentinel):
+        """Called after the request is dispatched and the response is
+        returned, right before the request context is popped.
+
+        This calls all functions decorated with
+        :meth:`teardown_request`, and :meth:`Blueprint.teardown_request`
+        if a blueprint handled the request. Finally, the
+        :data:`request_tearing_down` signal is sent.
+
+        This is called by
+        :meth:`RequestContext.pop() <flask.ctx.RequestContext.pop>`,
+        which may be delayed during testing to maintain access to
+        resources.
+
+        :param exc: An unhandled exception raised while dispatching the
+            request. Detected from the current exception information if
+            not passed. Passed to each teardown function.
+
+        .. versionchanged:: 0.9
+            Added the ``exc`` argument.
+        """
+        if exc is _sentinel:
+            exc = sys.exc_info()[1]
+        funcs = reversed(self.teardown_request_funcs.get(None, ()))
+        bp = _request_ctx_stack.top.request.blueprint
+        if bp is not None and bp in self.teardown_request_funcs:
+            funcs = chain(funcs, reversed(self.teardown_request_funcs[bp]))
+        for func in funcs:
+            func(exc)
+        request_tearing_down.send(self, exc=exc)
+
+    def do_teardown_appcontext(self, exc=_sentinel):
+        """Called right before the application context is popped.
+
+        When handling a request, the application context is popped
+        after the request context. See :meth:`do_teardown_request`.
+
+        This calls all functions decorated with
+        :meth:`teardown_appcontext`. Then the
+        :data:`appcontext_tearing_down` signal is sent.
+
+        This is called by
+        :meth:`AppContext.pop() <flask.ctx.AppContext.pop>`.
+
+        .. versionadded:: 0.9
+        """
+        if exc is _sentinel:
+            exc = sys.exc_info()[1]
+        for func in reversed(self.teardown_appcontext_funcs):
+            func(exc)
+        appcontext_tearing_down.send(self, exc=exc)
+
+    def app_context(self):
+        """Create an :class:`~flask.ctx.AppContext`. Use as a ``with``
+        block to push the context, which will make :data:`current_app`
+        point at this application.
+
+        An application context is automatically pushed by
+        :meth:`RequestContext.push() <flask.ctx.RequestContext.push>`
+        when handling a request, and when running a CLI command. Use
+        this to manually create a context outside of these situations.
+
+        ::
+
+            with app.app_context():
+                init_db()
+
+        See :doc:`/appcontext`.
+
+        .. versionadded:: 0.9
+        """
+        return AppContext(self)
+
+    def request_context(self, environ):
+        """Create a :class:`~flask.ctx.RequestContext` representing a
+        WSGI environment. Use a ``with`` block to push the context,
+        which will make :data:`request` point at this request.
+
+        See :doc:`/reqcontext`.
+
+        Typically you should not call this from your own code. A request
+        context is automatically pushed by the :meth:`wsgi_app` when
+        handling a request. Use :meth:`test_request_context` to create
+        an environment and context instead of this method.
+
+        :param environ: a WSGI environment
+        """
+        return RequestContext(self, environ)
+
+    def test_request_context(self, *args, **kwargs):
+        """Create a :class:`~flask.ctx.RequestContext` for a WSGI
+        environment created from the given values. This is mostly useful
+        during testing, where you may want to run a function that uses
+        request data without dispatching a full request.
+
+        See :doc:`/reqcontext`.
+
+        Use a ``with`` block to push the context, which will make
+        :data:`request` point at the request for the created
+        environment. ::
+
+            with test_request_context(...):
+                generate_report()
+
+        When using the shell, it may be easier to push and pop the
+        context manually to avoid indentation. ::
+
+            ctx = app.test_request_context(...)
+            ctx.push()
+            ...
+            ctx.pop()
+
+        Takes the same arguments as Werkzeug's
+        :class:`~werkzeug.test.EnvironBuilder`, with some defaults from
+        the application. See the linked Werkzeug docs for most of the
+        available arguments. Flask-specific behavior is listed here.
+
+        :param path: URL path being requested.
+        :param base_url: Base URL where the app is being served, which
+            ``path`` is relative to. If not given, built from
+            :data:`PREFERRED_URL_SCHEME`, ``subdomain``,
+            :data:`SERVER_NAME`, and :data:`APPLICATION_ROOT`.
+        :param subdomain: Subdomain name to append to
+            :data:`SERVER_NAME`.
+        :param url_scheme: Scheme to use instead of
+            :data:`PREFERRED_URL_SCHEME`.
+        :param data: The request body, either as a string or a dict of
+            form keys and values.
+        :param json: If given, this is serialized as JSON and passed as
+            ``data``. Also defaults ``content_type`` to
+            ``application/json``.
+        :param args: other positional arguments passed to
+            :class:`~werkzeug.test.EnvironBuilder`.
+        :param kwargs: other keyword arguments passed to
+            :class:`~werkzeug.test.EnvironBuilder`.
+        """
+        from flask.testing import make_test_environ_builder
+
+        builder = make_test_environ_builder(self, *args, **kwargs)
+
+        try:
+            return self.request_context(builder.get_environ())
+        finally:
+            builder.close()
+
+    def wsgi_app(self, environ, start_response):
+        """The actual WSGI application. This is not implemented in
+        :meth:`__call__` so that middlewares can be applied without
+        losing a reference to the app object. Instead of doing this::
+
+            app = MyMiddleware(app)
+
+        It's a better idea to do this instead::
+
+            app.wsgi_app = MyMiddleware(app.wsgi_app)
+
+        Then you still have the original application object around and
+        can continue to call methods on it.
+
+        .. versionchanged:: 0.7
+            Teardown events for the request and app contexts are called
+            even if an unhandled error occurs. Other events may not be
+            called depending on when an error occurs during dispatch.
+            See :ref:`callbacks-and-errors`.
+
+        :param environ: A WSGI environment.
+        :param start_response: A callable accepting a status code,
+            a list of headers, and an optional exception context to
+            start the response.
+        """
+        ctx = self.request_context(environ)
+        error = None
+        try:
+            try:
+                ctx.push()
+                response = self.full_dispatch_request()
+            except Exception as e:
+                error = e
+                response = self.handle_exception(e)
+            except:
+                error = sys.exc_info()[1]
+                raise
+            return response(environ, start_response)
+        finally:
+            if self.should_ignore_error(error):
+                error = None
+            ctx.auto_pop(error)
+
+    def __call__(self, environ, start_response):
+        """The WSGI server calls the Flask application object as the
+        WSGI application. This calls :meth:`wsgi_app` which can be
+        wrapped to applying middleware."""
+        return self.wsgi_app(environ, start_response)
+
+    def __repr__(self):
+        return '<%s %r>' % (
+            self.__class__.__name__,
+            self.name,
+        )
diff --git a/python/flask/blueprints.py b/python/flask/blueprints.py
new file mode 100644
index 0000000..c2158fe
--- /dev/null
+++ b/python/flask/blueprints.py
@@ -0,0 +1,447 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.blueprints
+    ~~~~~~~~~~~~~~~~
+
+    Blueprints are the recommended way to implement larger or more
+    pluggable applications in Flask 0.7 and later.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+from functools import update_wrapper
+
+from .helpers import _PackageBoundObject, _endpoint_from_view_func
+
+
+class BlueprintSetupState(object):
+    """Temporary holder object for registering a blueprint with the
+    application.  An instance of this class is created by the
+    :meth:`~flask.Blueprint.make_setup_state` method and later passed
+    to all register callback functions.
+    """
+
+    def __init__(self, blueprint, app, options, first_registration):
+        #: a reference to the current application
+        self.app = app
+
+        #: a reference to the blueprint that created this setup state.
+        self.blueprint = blueprint
+
+        #: a dictionary with all options that were passed to the
+        #: :meth:`~flask.Flask.register_blueprint` method.
+        self.options = options
+
+        #: as blueprints can be registered multiple times with the
+        #: application and not everything wants to be registered
+        #: multiple times on it, this attribute can be used to figure
+        #: out if the blueprint was registered in the past already.
+        self.first_registration = first_registration
+
+        subdomain = self.options.get('subdomain')
+        if subdomain is None:
+            subdomain = self.blueprint.subdomain
+
+        #: The subdomain that the blueprint should be active for, ``None``
+        #: otherwise.
+        self.subdomain = subdomain
+
+        url_prefix = self.options.get('url_prefix')
+        if url_prefix is None:
+            url_prefix = self.blueprint.url_prefix
+        #: The prefix that should be used for all URLs defined on the
+        #: blueprint.
+        self.url_prefix = url_prefix
+
+        #: A dictionary with URL defaults that is added to each and every
+        #: URL that was defined with the blueprint.
+        self.url_defaults = dict(self.blueprint.url_values_defaults)
+        self.url_defaults.update(self.options.get('url_defaults', ()))
+
+    def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
+        """A helper method to register a rule (and optionally a view function)
+        to the application.  The endpoint is automatically prefixed with the
+        blueprint's name.
+        """
+        if self.url_prefix is not None:
+            if rule:
+                rule = '/'.join((
+                    self.url_prefix.rstrip('/'), rule.lstrip('/')))
+            else:
+                rule = self.url_prefix
+        options.setdefault('subdomain', self.subdomain)
+        if endpoint is None:
+            endpoint = _endpoint_from_view_func(view_func)
+        defaults = self.url_defaults
+        if 'defaults' in options:
+            defaults = dict(defaults, **options.pop('defaults'))
+        self.app.add_url_rule(rule, '%s.%s' % (self.blueprint.name, endpoint),
+                              view_func, defaults=defaults, **options)
+
+
+class Blueprint(_PackageBoundObject):
+    """Represents a blueprint.  A blueprint is an object that records
+    functions that will be called with the
+    :class:`~flask.blueprints.BlueprintSetupState` later to register functions
+    or other things on the main application.  See :ref:`blueprints` for more
+    information.
+
+    .. versionadded:: 0.7
+    """
+
+    warn_on_modifications = False
+    _got_registered_once = False
+
+    #: Blueprint local JSON decoder class to use.
+    #: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_encoder`.
+    json_encoder = None
+    #: Blueprint local JSON decoder class to use.
+    #: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_decoder`.
+    json_decoder = None
+
+    # TODO remove the next three attrs when Sphinx :inherited-members: works
+    # https://github.com/sphinx-doc/sphinx/issues/741
+
+    #: The name of the package or module that this app belongs to. Do not
+    #: change this once it is set by the constructor.
+    import_name = None
+
+    #: Location of the template files to be added to the template lookup.
+    #: ``None`` if templates should not be added.
+    template_folder = None
+
+    #: Absolute path to the package on the filesystem. Used to look up
+    #: resources contained in the package.
+    root_path = None
+
+    def __init__(self, name, import_name, static_folder=None,
+                 static_url_path=None, template_folder=None,
+                 url_prefix=None, subdomain=None, url_defaults=None,
+                 root_path=None):
+        _PackageBoundObject.__init__(self, import_name, template_folder,
+                                     root_path=root_path)
+        self.name = name
+        self.url_prefix = url_prefix
+        self.subdomain = subdomain
+        self.static_folder = static_folder
+        self.static_url_path = static_url_path
+        self.deferred_functions = []
+        if url_defaults is None:
+            url_defaults = {}
+        self.url_values_defaults = url_defaults
+
+    def record(self, func):
+        """Registers a function that is called when the blueprint is
+        registered on the application.  This function is called with the
+        state as argument as returned by the :meth:`make_setup_state`
+        method.
+        """
+        if self._got_registered_once and self.warn_on_modifications:
+            from warnings import warn
+            warn(Warning('The blueprint was already registered once '
+                         'but is getting modified now.  These changes '
+                         'will not show up.'))
+        self.deferred_functions.append(func)
+
+    def record_once(self, func):
+        """Works like :meth:`record` but wraps the function in another
+        function that will ensure the function is only called once.  If the
+        blueprint is registered a second time on the application, the
+        function passed is not called.
+        """
+        def wrapper(state):
+            if state.first_registration:
+                func(state)
+        return self.record(update_wrapper(wrapper, func))
+
+    def make_setup_state(self, app, options, first_registration=False):
+        """Creates an instance of :meth:`~flask.blueprints.BlueprintSetupState`
+        object that is later passed to the register callback functions.
+        Subclasses can override this to return a subclass of the setup state.
+        """
+        return BlueprintSetupState(self, app, options, first_registration)
+
+    def register(self, app, options, first_registration=False):
+        """Called by :meth:`Flask.register_blueprint` to register all views
+        and callbacks registered on the blueprint with the application. Creates
+        a :class:`.BlueprintSetupState` and calls each :meth:`record` callback
+        with it.
+
+        :param app: The application this blueprint is being registered with.
+        :param options: Keyword arguments forwarded from
+            :meth:`~Flask.register_blueprint`.
+        :param first_registration: Whether this is the first time this
+            blueprint has been registered on the application.
+        """
+        self._got_registered_once = True
+        state = self.make_setup_state(app, options, first_registration)
+
+        if self.has_static_folder:
+            state.add_url_rule(
+                self.static_url_path + '/<path:filename>',
+                view_func=self.send_static_file, endpoint='static'
+            )
+
+        for deferred in self.deferred_functions:
+            deferred(state)
+
+    def route(self, rule, **options):
+        """Like :meth:`Flask.route` but for a blueprint.  The endpoint for the
+        :func:`url_for` function is prefixed with the name of the blueprint.
+        """
+        def decorator(f):
+            endpoint = options.pop("endpoint", f.__name__)
+            self.add_url_rule(rule, endpoint, f, **options)
+            return f
+        return decorator
+
+    def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
+        """Like :meth:`Flask.add_url_rule` but for a blueprint.  The endpoint for
+        the :func:`url_for` function is prefixed with the name of the blueprint.
+        """
+        if endpoint:
+            assert '.' not in endpoint, "Blueprint endpoints should not contain dots"
+        if view_func and hasattr(view_func, '__name__'):
+            assert '.' not in view_func.__name__, "Blueprint view function name should not contain dots"
+        self.record(lambda s:
+            s.add_url_rule(rule, endpoint, view_func, **options))
+
+    def endpoint(self, endpoint):
+        """Like :meth:`Flask.endpoint` but for a blueprint.  This does not
+        prefix the endpoint with the blueprint name, this has to be done
+        explicitly by the user of this method.  If the endpoint is prefixed
+        with a `.` it will be registered to the current blueprint, otherwise
+        it's an application independent endpoint.
+        """
+        def decorator(f):
+            def register_endpoint(state):
+                state.app.view_functions[endpoint] = f
+            self.record_once(register_endpoint)
+            return f
+        return decorator
+
+    def app_template_filter(self, name=None):
+        """Register a custom template filter, available application wide.  Like
+        :meth:`Flask.template_filter` but for a blueprint.
+
+        :param name: the optional name of the filter, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_app_template_filter(f, name=name)
+            return f
+        return decorator
+
+    def add_app_template_filter(self, f, name=None):
+        """Register a custom template filter, available application wide.  Like
+        :meth:`Flask.add_template_filter` but for a blueprint.  Works exactly
+        like the :meth:`app_template_filter` decorator.
+
+        :param name: the optional name of the filter, otherwise the
+                     function name will be used.
+        """
+        def register_template(state):
+            state.app.jinja_env.filters[name or f.__name__] = f
+        self.record_once(register_template)
+
+    def app_template_test(self, name=None):
+        """Register a custom template test, available application wide.  Like
+        :meth:`Flask.template_test` but for a blueprint.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the test, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_app_template_test(f, name=name)
+            return f
+        return decorator
+
+    def add_app_template_test(self, f, name=None):
+        """Register a custom template test, available application wide.  Like
+        :meth:`Flask.add_template_test` but for a blueprint.  Works exactly
+        like the :meth:`app_template_test` decorator.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the test, otherwise the
+                     function name will be used.
+        """
+        def register_template(state):
+            state.app.jinja_env.tests[name or f.__name__] = f
+        self.record_once(register_template)
+
+    def app_template_global(self, name=None):
+        """Register a custom template global, available application wide.  Like
+        :meth:`Flask.template_global` but for a blueprint.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the global, otherwise the
+                     function name will be used.
+        """
+        def decorator(f):
+            self.add_app_template_global(f, name=name)
+            return f
+        return decorator
+
+    def add_app_template_global(self, f, name=None):
+        """Register a custom template global, available application wide.  Like
+        :meth:`Flask.add_template_global` but for a blueprint.  Works exactly
+        like the :meth:`app_template_global` decorator.
+
+        .. versionadded:: 0.10
+
+        :param name: the optional name of the global, otherwise the
+                     function name will be used.
+        """
+        def register_template(state):
+            state.app.jinja_env.globals[name or f.__name__] = f
+        self.record_once(register_template)
+
+    def before_request(self, f):
+        """Like :meth:`Flask.before_request` but for a blueprint.  This function
+        is only executed before each request that is handled by a function of
+        that blueprint.
+        """
+        self.record_once(lambda s: s.app.before_request_funcs
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def before_app_request(self, f):
+        """Like :meth:`Flask.before_request`.  Such a function is executed
+        before each request, even if outside of a blueprint.
+        """
+        self.record_once(lambda s: s.app.before_request_funcs
+            .setdefault(None, []).append(f))
+        return f
+
+    def before_app_first_request(self, f):
+        """Like :meth:`Flask.before_first_request`.  Such a function is
+        executed before the first request to the application.
+        """
+        self.record_once(lambda s: s.app.before_first_request_funcs.append(f))
+        return f
+
+    def after_request(self, f):
+        """Like :meth:`Flask.after_request` but for a blueprint.  This function
+        is only executed after each request that is handled by a function of
+        that blueprint.
+        """
+        self.record_once(lambda s: s.app.after_request_funcs
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def after_app_request(self, f):
+        """Like :meth:`Flask.after_request` but for a blueprint.  Such a function
+        is executed after each request, even if outside of the blueprint.
+        """
+        self.record_once(lambda s: s.app.after_request_funcs
+            .setdefault(None, []).append(f))
+        return f
+
+    def teardown_request(self, f):
+        """Like :meth:`Flask.teardown_request` but for a blueprint.  This
+        function is only executed when tearing down requests handled by a
+        function of that blueprint.  Teardown request functions are executed
+        when the request context is popped, even when no actual request was
+        performed.
+        """
+        self.record_once(lambda s: s.app.teardown_request_funcs
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def teardown_app_request(self, f):
+        """Like :meth:`Flask.teardown_request` but for a blueprint.  Such a
+        function is executed when tearing down each request, even if outside of
+        the blueprint.
+        """
+        self.record_once(lambda s: s.app.teardown_request_funcs
+            .setdefault(None, []).append(f))
+        return f
+
+    def context_processor(self, f):
+        """Like :meth:`Flask.context_processor` but for a blueprint.  This
+        function is only executed for requests handled by a blueprint.
+        """
+        self.record_once(lambda s: s.app.template_context_processors
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def app_context_processor(self, f):
+        """Like :meth:`Flask.context_processor` but for a blueprint.  Such a
+        function is executed each request, even if outside of the blueprint.
+        """
+        self.record_once(lambda s: s.app.template_context_processors
+            .setdefault(None, []).append(f))
+        return f
+
+    def app_errorhandler(self, code):
+        """Like :meth:`Flask.errorhandler` but for a blueprint.  This
+        handler is used for all requests, even if outside of the blueprint.
+        """
+        def decorator(f):
+            self.record_once(lambda s: s.app.errorhandler(code)(f))
+            return f
+        return decorator
+
+    def url_value_preprocessor(self, f):
+        """Registers a function as URL value preprocessor for this
+        blueprint.  It's called before the view functions are called and
+        can modify the url values provided.
+        """
+        self.record_once(lambda s: s.app.url_value_preprocessors
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def url_defaults(self, f):
+        """Callback function for URL defaults for this blueprint.  It's called
+        with the endpoint and values and should update the values passed
+        in place.
+        """
+        self.record_once(lambda s: s.app.url_default_functions
+            .setdefault(self.name, []).append(f))
+        return f
+
+    def app_url_value_preprocessor(self, f):
+        """Same as :meth:`url_value_preprocessor` but application wide.
+        """
+        self.record_once(lambda s: s.app.url_value_preprocessors
+            .setdefault(None, []).append(f))
+        return f
+
+    def app_url_defaults(self, f):
+        """Same as :meth:`url_defaults` but application wide.
+        """
+        self.record_once(lambda s: s.app.url_default_functions
+            .setdefault(None, []).append(f))
+        return f
+
+    def errorhandler(self, code_or_exception):
+        """Registers an error handler that becomes active for this blueprint
+        only.  Please be aware that routing does not happen local to a
+        blueprint so an error handler for 404 usually is not handled by
+        a blueprint unless it is caused inside a view function.  Another
+        special case is the 500 internal server error which is always looked
+        up from the application.
+
+        Otherwise works as the :meth:`~flask.Flask.errorhandler` decorator
+        of the :class:`~flask.Flask` object.
+        """
+        def decorator(f):
+            self.record_once(lambda s: s.app._register_error_handler(
+                self.name, code_or_exception, f))
+            return f
+        return decorator
+
+    def register_error_handler(self, code_or_exception, f):
+        """Non-decorator version of the :meth:`errorhandler` error attach
+        function, akin to the :meth:`~flask.Flask.register_error_handler`
+        application-wide function of the :class:`~flask.Flask` object but
+        for error handlers limited to this blueprint.
+
+        .. versionadded:: 0.11
+        """
+        self.record_once(lambda s: s.app._register_error_handler(
+            self.name, code_or_exception, f))
diff --git a/python/flask/cli.py b/python/flask/cli.py
new file mode 100644
index 0000000..3eb93b3
--- /dev/null
+++ b/python/flask/cli.py
@@ -0,0 +1,910 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.cli
+    ~~~~~~~~~
+
+    A simple command line application to run flask apps.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from __future__ import print_function
+
+import ast
+import inspect
+import os
+import platform
+import re
+import ssl
+import sys
+import traceback
+from functools import update_wrapper
+from operator import attrgetter
+from threading import Lock, Thread
+
+import click
+from werkzeug.utils import import_string
+
+from . import __version__
+from ._compat import getargspec, iteritems, reraise, text_type
+from .globals import current_app
+from .helpers import get_debug_flag, get_env, get_load_dotenv
+
+try:
+    import dotenv
+except ImportError:
+    dotenv = None
+
+
+class NoAppException(click.UsageError):
+    """Raised if an application cannot be found or loaded."""
+
+
+def find_best_app(script_info, module):
+    """Given a module instance this tries to find the best possible
+    application in the module or raises an exception.
+    """
+    from . import Flask
+
+    # Search for the most common names first.
+    for attr_name in ('app', 'application'):
+        app = getattr(module, attr_name, None)
+
+        if isinstance(app, Flask):
+            return app
+
+    # Otherwise find the only object that is a Flask instance.
+    matches = [
+        v for k, v in iteritems(module.__dict__) if isinstance(v, Flask)
+    ]
+
+    if len(matches) == 1:
+        return matches[0]
+    elif len(matches) > 1:
+        raise NoAppException(
+            'Detected multiple Flask applications in module "{module}". Use '
+            '"FLASK_APP={module}:name" to specify the correct '
+            'one.'.format(module=module.__name__)
+        )
+
+    # Search for app factory functions.
+    for attr_name in ('create_app', 'make_app'):
+        app_factory = getattr(module, attr_name, None)
+
+        if inspect.isfunction(app_factory):
+            try:
+                app = call_factory(script_info, app_factory)
+
+                if isinstance(app, Flask):
+                    return app
+            except TypeError:
+                if not _called_with_wrong_args(app_factory):
+                    raise
+                raise NoAppException(
+                    'Detected factory "{factory}" in module "{module}", but '
+                    'could not call it without arguments. Use '
+                    '"FLASK_APP=\'{module}:{factory}(args)\'" to specify '
+                    'arguments.'.format(
+                        factory=attr_name, module=module.__name__
+                    )
+                )
+
+    raise NoAppException(
+        'Failed to find Flask application or factory in module "{module}". '
+        'Use "FLASK_APP={module}:name to specify one.'.format(
+            module=module.__name__
+        )
+    )
+
+
+def call_factory(script_info, app_factory, arguments=()):
+    """Takes an app factory, a ``script_info` object and  optionally a tuple
+    of arguments. Checks for the existence of a script_info argument and calls
+    the app_factory depending on that and the arguments provided.
+    """
+    args_spec = getargspec(app_factory)
+    arg_names = args_spec.args
+    arg_defaults = args_spec.defaults
+
+    if 'script_info' in arg_names:
+        return app_factory(*arguments, script_info=script_info)
+    elif arguments:
+        return app_factory(*arguments)
+    elif not arguments and len(arg_names) == 1 and arg_defaults is None:
+        return app_factory(script_info)
+
+    return app_factory()
+
+
+def _called_with_wrong_args(factory):
+    """Check whether calling a function raised a ``TypeError`` because
+    the call failed or because something in the factory raised the
+    error.
+
+    :param factory: the factory function that was called
+    :return: true if the call failed
+    """
+    tb = sys.exc_info()[2]
+
+    try:
+        while tb is not None:
+            if tb.tb_frame.f_code is factory.__code__:
+                # in the factory, it was called successfully
+                return False
+
+            tb = tb.tb_next
+
+        # didn't reach the factory
+        return True
+    finally:
+        del tb
+
+
+def find_app_by_string(script_info, module, app_name):
+    """Checks if the given string is a variable name or a function. If it is a
+    function, it checks for specified arguments and whether it takes a
+    ``script_info`` argument and calls the function with the appropriate
+    arguments.
+    """
+    from flask import Flask
+    match = re.match(r'^ *([^ ()]+) *(?:\((.*?) *,? *\))? *$', app_name)
+
+    if not match:
+        raise NoAppException(
+            '"{name}" is not a valid variable name or function '
+            'expression.'.format(name=app_name)
+        )
+
+    name, args = match.groups()
+
+    try:
+        attr = getattr(module, name)
+    except AttributeError as e:
+        raise NoAppException(e.args[0])
+
+    if inspect.isfunction(attr):
+        if args:
+            try:
+                args = ast.literal_eval('({args},)'.format(args=args))
+            except (ValueError, SyntaxError)as e:
+                raise NoAppException(
+                    'Could not parse the arguments in '
+                    '"{app_name}".'.format(e=e, app_name=app_name)
+                )
+        else:
+            args = ()
+
+        try:
+            app = call_factory(script_info, attr, args)
+        except TypeError as e:
+            if not _called_with_wrong_args(attr):
+                raise
+
+            raise NoAppException(
+                '{e}\nThe factory "{app_name}" in module "{module}" could not '
+                'be called with the specified arguments.'.format(
+                    e=e, app_name=app_name, module=module.__name__
+                )
+            )
+    else:
+        app = attr
+
+    if isinstance(app, Flask):
+        return app
+
+    raise NoAppException(
+        'A valid Flask application was not obtained from '
+        '"{module}:{app_name}".'.format(
+            module=module.__name__, app_name=app_name
+        )
+    )
+
+
+def prepare_import(path):
+    """Given a filename this will try to calculate the python path, add it
+    to the search path and return the actual module name that is expected.
+    """
+    path = os.path.realpath(path)
+
+    if os.path.splitext(path)[1] == '.py':
+        path = os.path.splitext(path)[0]
+
+    if os.path.basename(path) == '__init__':
+        path = os.path.dirname(path)
+
+    module_name = []
+
+    # move up until outside package structure (no __init__.py)
+    while True:
+        path, name = os.path.split(path)
+        module_name.append(name)
+
+        if not os.path.exists(os.path.join(path, '__init__.py')):
+            break
+
+    if sys.path[0] != path:
+        sys.path.insert(0, path)
+
+    return '.'.join(module_name[::-1])
+
+
+def locate_app(script_info, module_name, app_name, raise_if_not_found=True):
+    __traceback_hide__ = True
+
+    try:
+        __import__(module_name)
+    except ImportError:
+        # Reraise the ImportError if it occurred within the imported module.
+        # Determine this by checking whether the trace has a depth > 1.
+        if sys.exc_info()[-1].tb_next:
+            raise NoAppException(
+                'While importing "{name}", an ImportError was raised:'
+                '\n\n{tb}'.format(name=module_name, tb=traceback.format_exc())
+            )
+        elif raise_if_not_found:
+            raise NoAppException(
+                'Could not import "{name}".'.format(name=module_name)
+            )
+        else:
+            return
+
+    module = sys.modules[module_name]
+
+    if app_name is None:
+        return find_best_app(script_info, module)
+    else:
+        return find_app_by_string(script_info, module, app_name)
+
+
+def get_version(ctx, param, value):
+    if not value or ctx.resilient_parsing:
+        return
+    import werkzeug
+    message = (
+        'Python %(python)s\n'
+        'Flask %(flask)s\n'
+        'Werkzeug %(werkzeug)s'
+    )
+    click.echo(message % {
+        'python': platform.python_version(),
+        'flask': __version__,
+        'werkzeug': werkzeug.__version__,
+    }, color=ctx.color)
+    ctx.exit()
+
+
+version_option = click.Option(
+    ['--version'],
+    help='Show the flask version',
+    expose_value=False,
+    callback=get_version,
+    is_flag=True,
+    is_eager=True
+)
+
+
+class DispatchingApp(object):
+    """Special application that dispatches to a Flask application which
+    is imported by name in a background thread.  If an error happens
+    it is recorded and shown as part of the WSGI handling which in case
+    of the Werkzeug debugger means that it shows up in the browser.
+    """
+
+    def __init__(self, loader, use_eager_loading=False):
+        self.loader = loader
+        self._app = None
+        self._lock = Lock()
+        self._bg_loading_exc_info = None
+        if use_eager_loading:
+            self._load_unlocked()
+        else:
+            self._load_in_background()
+
+    def _load_in_background(self):
+        def _load_app():
+            __traceback_hide__ = True
+            with self._lock:
+                try:
+                    self._load_unlocked()
+                except Exception:
+                    self._bg_loading_exc_info = sys.exc_info()
+        t = Thread(target=_load_app, args=())
+        t.start()
+
+    def _flush_bg_loading_exception(self):
+        __traceback_hide__ = True
+        exc_info = self._bg_loading_exc_info
+        if exc_info is not None:
+            self._bg_loading_exc_info = None
+            reraise(*exc_info)
+
+    def _load_unlocked(self):
+        __traceback_hide__ = True
+        self._app = rv = self.loader()
+        self._bg_loading_exc_info = None
+        return rv
+
+    def __call__(self, environ, start_response):
+        __traceback_hide__ = True
+        if self._app is not None:
+            return self._app(environ, start_response)
+        self._flush_bg_loading_exception()
+        with self._lock:
+            if self._app is not None:
+                rv = self._app
+            else:
+                rv = self._load_unlocked()
+            return rv(environ, start_response)
+
+
+class ScriptInfo(object):
+    """Helper object to deal with Flask applications.  This is usually not
+    necessary to interface with as it's used internally in the dispatching
+    to click.  In future versions of Flask this object will most likely play
+    a bigger role.  Typically it's created automatically by the
+    :class:`FlaskGroup` but you can also manually create it and pass it
+    onwards as click object.
+    """
+
+    def __init__(self, app_import_path=None, create_app=None,
+                 set_debug_flag=True):
+        #: Optionally the import path for the Flask application.
+        self.app_import_path = app_import_path or os.environ.get('FLASK_APP')
+        #: Optionally a function that is passed the script info to create
+        #: the instance of the application.
+        self.create_app = create_app
+        #: A dictionary with arbitrary data that can be associated with
+        #: this script info.
+        self.data = {}
+        self.set_debug_flag = set_debug_flag
+        self._loaded_app = None
+
+    def load_app(self):
+        """Loads the Flask app (if not yet loaded) and returns it.  Calling
+        this multiple times will just result in the already loaded app to
+        be returned.
+        """
+        __traceback_hide__ = True
+
+        if self._loaded_app is not None:
+            return self._loaded_app
+
+        app = None
+
+        if self.create_app is not None:
+            app = call_factory(self, self.create_app)
+        else:
+            if self.app_import_path:
+                path, name = (re.split(r':(?![\\/])', self.app_import_path, 1) + [None])[:2]
+                import_name = prepare_import(path)
+                app = locate_app(self, import_name, name)
+            else:
+                for path in ('wsgi.py', 'app.py'):
+                    import_name = prepare_import(path)
+                    app = locate_app(self, import_name, None,
+                                     raise_if_not_found=False)
+
+                    if app:
+                        break
+
+        if not app:
+            raise NoAppException(
+                'Could not locate a Flask application. You did not provide '
+                'the "FLASK_APP" environment variable, and a "wsgi.py" or '
+                '"app.py" module was not found in the current directory.'
+            )
+
+        if self.set_debug_flag:
+            # Update the app's debug flag through the descriptor so that
+            # other values repopulate as well.
+            app.debug = get_debug_flag()
+
+        self._loaded_app = app
+        return app
+
+
+pass_script_info = click.make_pass_decorator(ScriptInfo, ensure=True)
+
+
+def with_appcontext(f):
+    """Wraps a callback so that it's guaranteed to be executed with the
+    script's application context.  If callbacks are registered directly
+    to the ``app.cli`` object then they are wrapped with this function
+    by default unless it's disabled.
+    """
+    @click.pass_context
+    def decorator(__ctx, *args, **kwargs):
+        with __ctx.ensure_object(ScriptInfo).load_app().app_context():
+            return __ctx.invoke(f, *args, **kwargs)
+    return update_wrapper(decorator, f)
+
+
+class AppGroup(click.Group):
+    """This works similar to a regular click :class:`~click.Group` but it
+    changes the behavior of the :meth:`command` decorator so that it
+    automatically wraps the functions in :func:`with_appcontext`.
+
+    Not to be confused with :class:`FlaskGroup`.
+    """
+
+    def command(self, *args, **kwargs):
+        """This works exactly like the method of the same name on a regular
+        :class:`click.Group` but it wraps callbacks in :func:`with_appcontext`
+        unless it's disabled by passing ``with_appcontext=False``.
+        """
+        wrap_for_ctx = kwargs.pop('with_appcontext', True)
+        def decorator(f):
+            if wrap_for_ctx:
+                f = with_appcontext(f)
+            return click.Group.command(self, *args, **kwargs)(f)
+        return decorator
+
+    def group(self, *args, **kwargs):
+        """This works exactly like the method of the same name on a regular
+        :class:`click.Group` but it defaults the group class to
+        :class:`AppGroup`.
+        """
+        kwargs.setdefault('cls', AppGroup)
+        return click.Group.group(self, *args, **kwargs)
+
+
+class FlaskGroup(AppGroup):
+    """Special subclass of the :class:`AppGroup` group that supports
+    loading more commands from the configured Flask app.  Normally a
+    developer does not have to interface with this class but there are
+    some very advanced use cases for which it makes sense to create an
+    instance of this.
+
+    For information as of why this is useful see :ref:`custom-scripts`.
+
+    :param add_default_commands: if this is True then the default run and
+        shell commands wil be added.
+    :param add_version_option: adds the ``--version`` option.
+    :param create_app: an optional callback that is passed the script info and
+        returns the loaded app.
+    :param load_dotenv: Load the nearest :file:`.env` and :file:`.flaskenv`
+        files to set environment variables. Will also change the working
+        directory to the directory containing the first file found.
+    :param set_debug_flag: Set the app's debug flag based on the active
+        environment
+
+    .. versionchanged:: 1.0
+        If installed, python-dotenv will be used to load environment variables
+        from :file:`.env` and :file:`.flaskenv` files.
+    """
+
+    def __init__(self, add_default_commands=True, create_app=None,
+                 add_version_option=True, load_dotenv=True,
+                 set_debug_flag=True, **extra):
+        params = list(extra.pop('params', None) or ())
+
+        if add_version_option:
+            params.append(version_option)
+
+        AppGroup.__init__(self, params=params, **extra)
+        self.create_app = create_app
+        self.load_dotenv = load_dotenv
+        self.set_debug_flag = set_debug_flag
+
+        if add_default_commands:
+            self.add_command(run_command)
+            self.add_command(shell_command)
+            self.add_command(routes_command)
+
+        self._loaded_plugin_commands = False
+
+    def _load_plugin_commands(self):
+        if self._loaded_plugin_commands:
+            return
+        try:
+            import pkg_resources
+        except ImportError:
+            self._loaded_plugin_commands = True
+            return
+
+        for ep in pkg_resources.iter_entry_points('flask.commands'):
+            self.add_command(ep.load(), ep.name)
+        self._loaded_plugin_commands = True
+
+    def get_command(self, ctx, name):
+        self._load_plugin_commands()
+
+        # We load built-in commands first as these should always be the
+        # same no matter what the app does.  If the app does want to
+        # override this it needs to make a custom instance of this group
+        # and not attach the default commands.
+        #
+        # This also means that the script stays functional in case the
+        # application completely fails.
+        rv = AppGroup.get_command(self, ctx, name)
+        if rv is not None:
+            return rv
+
+        info = ctx.ensure_object(ScriptInfo)
+        try:
+            rv = info.load_app().cli.get_command(ctx, name)
+            if rv is not None:
+                return rv
+        except NoAppException:
+            pass
+
+    def list_commands(self, ctx):
+        self._load_plugin_commands()
+
+        # The commands available is the list of both the application (if
+        # available) plus the builtin commands.
+        rv = set(click.Group.list_commands(self, ctx))
+        info = ctx.ensure_object(ScriptInfo)
+        try:
+            rv.update(info.load_app().cli.list_commands(ctx))
+        except Exception:
+            # Here we intentionally swallow all exceptions as we don't
+            # want the help page to break if the app does not exist.
+            # If someone attempts to use the command we try to create
+            # the app again and this will give us the error.
+            # However, we will not do so silently because that would confuse
+            # users.
+            traceback.print_exc()
+        return sorted(rv)
+
+    def main(self, *args, **kwargs):
+        # Set a global flag that indicates that we were invoked from the
+        # command line interface. This is detected by Flask.run to make the
+        # call into a no-op. This is necessary to avoid ugly errors when the
+        # script that is loaded here also attempts to start a server.
+        os.environ['FLASK_RUN_FROM_CLI'] = 'true'
+
+        if get_load_dotenv(self.load_dotenv):
+            load_dotenv()
+
+        obj = kwargs.get('obj')
+
+        if obj is None:
+            obj = ScriptInfo(create_app=self.create_app,
+                             set_debug_flag=self.set_debug_flag)
+
+        kwargs['obj'] = obj
+        kwargs.setdefault('auto_envvar_prefix', 'FLASK')
+        return super(FlaskGroup, self).main(*args, **kwargs)
+
+
+def _path_is_ancestor(path, other):
+    """Take ``other`` and remove the length of ``path`` from it. Then join it
+    to ``path``. If it is the original value, ``path`` is an ancestor of
+    ``other``."""
+    return os.path.join(path, other[len(path):].lstrip(os.sep)) == other
+
+
+def load_dotenv(path=None):
+    """Load "dotenv" files in order of precedence to set environment variables.
+
+    If an env var is already set it is not overwritten, so earlier files in the
+    list are preferred over later files.
+
+    Changes the current working directory to the location of the first file
+    found, with the assumption that it is in the top level project directory
+    and will be where the Python path should import local packages from.
+
+    This is a no-op if `python-dotenv`_ is not installed.
+
+    .. _python-dotenv: https://github.com/theskumar/python-dotenv#readme
+
+    :param path: Load the file at this location instead of searching.
+    :return: ``True`` if a file was loaded.
+
+    .. versionadded:: 1.0
+    """
+    if dotenv is None:
+        if path or os.path.exists('.env') or os.path.exists('.flaskenv'):
+            click.secho(
+                ' * Tip: There are .env files present.'
+                ' Do "pip install python-dotenv" to use them.',
+                fg='yellow')
+        return
+
+    if path is not None:
+        return dotenv.load_dotenv(path)
+
+    new_dir = None
+
+    for name in ('.env', '.flaskenv'):
+        path = dotenv.find_dotenv(name, usecwd=True)
+
+        if not path:
+            continue
+
+        if new_dir is None:
+            new_dir = os.path.dirname(path)
+
+        dotenv.load_dotenv(path)
+
+    if new_dir and os.getcwd() != new_dir:
+        os.chdir(new_dir)
+
+    return new_dir is not None  # at least one file was located and loaded
+
+
+def show_server_banner(env, debug, app_import_path, eager_loading):
+    """Show extra startup messages the first time the server is run,
+    ignoring the reloader.
+    """
+    if os.environ.get('WERKZEUG_RUN_MAIN') == 'true':
+        return
+
+    if app_import_path is not None:
+        message = ' * Serving Flask app "{0}"'.format(app_import_path)
+
+        if not eager_loading:
+            message += ' (lazy loading)'
+
+        click.echo(message)
+
+    click.echo(' * Environment: {0}'.format(env))
+
+    if env == 'production':
+        click.secho(
+            '   WARNING: This is a development server. '
+            'Do not use it in a production deployment.', fg='red')
+        click.secho('   Use a production WSGI server instead.', dim=True)
+
+    if debug is not None:
+        click.echo(' * Debug mode: {0}'.format('on' if debug else 'off'))
+
+
+class CertParamType(click.ParamType):
+    """Click option type for the ``--cert`` option. Allows either an
+    existing file, the string ``'adhoc'``, or an import for a
+    :class:`~ssl.SSLContext` object.
+    """
+
+    name = 'path'
+
+    def __init__(self):
+        self.path_type = click.Path(
+            exists=True, dir_okay=False, resolve_path=True)
+
+    def convert(self, value, param, ctx):
+        try:
+            return self.path_type(value, param, ctx)
+        except click.BadParameter:
+            value = click.STRING(value, param, ctx).lower()
+
+            if value == 'adhoc':
+                try:
+                    import OpenSSL
+                except ImportError:
+                    raise click.BadParameter(
+                        'Using ad-hoc certificates requires pyOpenSSL.',
+                        ctx, param)
+
+                return value
+
+            obj = import_string(value, silent=True)
+
+            if sys.version_info < (2, 7, 9):
+                if obj:
+                    return obj
+            else:
+                if isinstance(obj, ssl.SSLContext):
+                    return obj
+
+            raise
+
+
+def _validate_key(ctx, param, value):
+    """The ``--key`` option must be specified when ``--cert`` is a file.
+    Modifies the ``cert`` param to be a ``(cert, key)`` pair if needed.
+    """
+    cert = ctx.params.get('cert')
+    is_adhoc = cert == 'adhoc'
+
+    if sys.version_info < (2, 7, 9):
+        is_context = cert and not isinstance(cert, (text_type, bytes))
+    else:
+        is_context = isinstance(cert, ssl.SSLContext)
+
+    if value is not None:
+        if is_adhoc:
+            raise click.BadParameter(
+                'When "--cert" is "adhoc", "--key" is not used.',
+                ctx, param)
+
+        if is_context:
+            raise click.BadParameter(
+                'When "--cert" is an SSLContext object, "--key is not used.',
+                ctx, param)
+
+        if not cert:
+            raise click.BadParameter(
+                '"--cert" must also be specified.',
+                ctx, param)
+
+        ctx.params['cert'] = cert, value
+
+    else:
+        if cert and not (is_adhoc or is_context):
+            raise click.BadParameter(
+                'Required when using "--cert".',
+                ctx, param)
+
+    return value
+
+
+@click.command('run', short_help='Run a development server.')
+@click.option('--host', '-h', default='127.0.0.1',
+              help='The interface to bind to.')
+@click.option('--port', '-p', default=5000,
+              help='The port to bind to.')
+@click.option('--cert', type=CertParamType(),
+              help='Specify a certificate file to use HTTPS.')
+@click.option('--key',
+              type=click.Path(exists=True, dir_okay=False, resolve_path=True),
+              callback=_validate_key, expose_value=False,
+              help='The key file to use when specifying a certificate.')
+@click.option('--reload/--no-reload', default=None,
+              help='Enable or disable the reloader. By default the reloader '
+              'is active if debug is enabled.')
+@click.option('--debugger/--no-debugger', default=None,
+              help='Enable or disable the debugger. By default the debugger '
+              'is active if debug is enabled.')
+@click.option('--eager-loading/--lazy-loader', default=None,
+              help='Enable or disable eager loading. By default eager '
+              'loading is enabled if the reloader is disabled.')
+@click.option('--with-threads/--without-threads', default=True,
+              help='Enable or disable multithreading.')
+@pass_script_info
+def run_command(info, host, port, reload, debugger, eager_loading,
+                with_threads, cert):
+    """Run a local development server.
+
+    This server is for development purposes only. It does not provide
+    the stability, security, or performance of production WSGI servers.
+
+    The reloader and debugger are enabled by default if
+    FLASK_ENV=development or FLASK_DEBUG=1.
+    """
+    debug = get_debug_flag()
+
+    if reload is None:
+        reload = debug
+
+    if debugger is None:
+        debugger = debug
+
+    if eager_loading is None:
+        eager_loading = not reload
+
+    show_server_banner(get_env(), debug, info.app_import_path, eager_loading)
+    app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)
+
+    from werkzeug.serving import run_simple
+    run_simple(host, port, app, use_reloader=reload, use_debugger=debugger,
+               threaded=with_threads, ssl_context=cert)
+
+
+@click.command('shell', short_help='Run a shell in the app context.')
+@with_appcontext
+def shell_command():
+    """Run an interactive Python shell in the context of a given
+    Flask application.  The application will populate the default
+    namespace of this shell according to it's configuration.
+
+    This is useful for executing small snippets of management code
+    without having to manually configure the application.
+    """
+    import code
+    from flask.globals import _app_ctx_stack
+    app = _app_ctx_stack.top.app
+    banner = 'Python %s on %s\nApp: %s [%s]\nInstance: %s' % (
+        sys.version,
+        sys.platform,
+        app.import_name,
+        app.env,
+        app.instance_path,
+    )
+    ctx = {}
+
+    # Support the regular Python interpreter startup script if someone
+    # is using it.
+    startup = os.environ.get('PYTHONSTARTUP')
+    if startup and os.path.isfile(startup):
+        with open(startup, 'r') as f:
+            eval(compile(f.read(), startup, 'exec'), ctx)
+
+    ctx.update(app.make_shell_context())
+
+    code.interact(banner=banner, local=ctx)
+
+
+@click.command('routes', short_help='Show the routes for the app.')
+@click.option(
+    '--sort', '-s',
+    type=click.Choice(('endpoint', 'methods', 'rule', 'match')),
+    default='endpoint',
+    help=(
+        'Method to sort routes by. "match" is the order that Flask will match '
+        'routes when dispatching a request.'
+    )
+)
+@click.option(
+    '--all-methods',
+    is_flag=True,
+    help="Show HEAD and OPTIONS methods."
+)
+@with_appcontext
+def routes_command(sort, all_methods):
+    """Show all registered routes with endpoints and methods."""
+
+    rules = list(current_app.url_map.iter_rules())
+    if not rules:
+        click.echo('No routes were registered.')
+        return
+
+    ignored_methods = set(() if all_methods else ('HEAD', 'OPTIONS'))
+
+    if sort in ('endpoint', 'rule'):
+        rules = sorted(rules, key=attrgetter(sort))
+    elif sort == 'methods':
+        rules = sorted(rules, key=lambda rule: sorted(rule.methods))
+
+    rule_methods = [
+        ', '.join(sorted(rule.methods - ignored_methods)) for rule in rules
+    ]
+
+    headers = ('Endpoint', 'Methods', 'Rule')
+    widths = (
+        max(len(rule.endpoint) for rule in rules),
+        max(len(methods) for methods in rule_methods),
+        max(len(rule.rule) for rule in rules),
+    )
+    widths = [max(len(h), w) for h, w in zip(headers, widths)]
+    row = '{{0:<{0}}}  {{1:<{1}}}  {{2:<{2}}}'.format(*widths)
+
+    click.echo(row.format(*headers).strip())
+    click.echo(row.format(*('-' * width for width in widths)))
+
+    for rule, methods in zip(rules, rule_methods):
+        click.echo(row.format(rule.endpoint, methods, rule.rule).rstrip())
+
+
+cli = FlaskGroup(help="""\
+A general utility script for Flask applications.
+
+Provides commands from Flask, extensions, and the application. Loads the
+application defined in the FLASK_APP environment variable, or from a wsgi.py
+file. Setting the FLASK_ENV environment variable to 'development' will enable
+debug mode.
+
+\b
+  {prefix}{cmd} FLASK_APP=hello.py
+  {prefix}{cmd} FLASK_ENV=development
+  {prefix}flask run
+""".format(
+    cmd='export' if os.name == 'posix' else 'set',
+    prefix='$ ' if os.name == 'posix' else '> '
+))
+
+
+def main(as_module=False):
+    args = sys.argv[1:]
+
+    if as_module:
+        this_module = 'flask'
+
+        if sys.version_info < (2, 7):
+            this_module += '.cli'
+
+        name = 'python -m ' + this_module
+
+        # Python rewrites "python -m flask" to the path to the file in argv.
+        # Restore the original command so that the reloader works.
+        sys.argv = ['-m', this_module] + args
+    else:
+        name = None
+
+    cli.main(args=args, prog_name=name)
+
+
+if __name__ == '__main__':
+    main(as_module=True)
diff --git a/python/flask/config.py b/python/flask/config.py
new file mode 100644
index 0000000..a5475ed
--- /dev/null
+++ b/python/flask/config.py
@@ -0,0 +1,269 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.config
+    ~~~~~~~~~~~~
+
+    Implements the configuration related objects.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import os
+import types
+import errno
+
+from werkzeug.utils import import_string
+from ._compat import string_types, iteritems
+from . import json
+
+
+class ConfigAttribute(object):
+    """Makes an attribute forward to the config"""
+
+    def __init__(self, name, get_converter=None):
+        self.__name__ = name
+        self.get_converter = get_converter
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+        rv = obj.config[self.__name__]
+        if self.get_converter is not None:
+            rv = self.get_converter(rv)
+        return rv
+
+    def __set__(self, obj, value):
+        obj.config[self.__name__] = value
+
+
+class Config(dict):
+    """Works exactly like a dict but provides ways to fill it from files
+    or special dictionaries.  There are two common patterns to populate the
+    config.
+
+    Either you can fill the config from a config file::
+
+        app.config.from_pyfile('yourconfig.cfg')
+
+    Or alternatively you can define the configuration options in the
+    module that calls :meth:`from_object` or provide an import path to
+    a module that should be loaded.  It is also possible to tell it to
+    use the same module and with that provide the configuration values
+    just before the call::
+
+        DEBUG = True
+        SECRET_KEY = 'development key'
+        app.config.from_object(__name__)
+
+    In both cases (loading from any Python file or loading from modules),
+    only uppercase keys are added to the config.  This makes it possible to use
+    lowercase values in the config file for temporary values that are not added
+    to the config or to define the config keys in the same file that implements
+    the application.
+
+    Probably the most interesting way to load configurations is from an
+    environment variable pointing to a file::
+
+        app.config.from_envvar('YOURAPPLICATION_SETTINGS')
+
+    In this case before launching the application you have to set this
+    environment variable to the file you want to use.  On Linux and OS X
+    use the export statement::
+
+        export YOURAPPLICATION_SETTINGS='/path/to/config/file'
+
+    On windows use `set` instead.
+
+    :param root_path: path to which files are read relative from.  When the
+                      config object is created by the application, this is
+                      the application's :attr:`~flask.Flask.root_path`.
+    :param defaults: an optional dictionary of default values
+    """
+
+    def __init__(self, root_path, defaults=None):
+        dict.__init__(self, defaults or {})
+        self.root_path = root_path
+
+    def from_envvar(self, variable_name, silent=False):
+        """Loads a configuration from an environment variable pointing to
+        a configuration file.  This is basically just a shortcut with nicer
+        error messages for this line of code::
+
+            app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])
+
+        :param variable_name: name of the environment variable
+        :param silent: set to ``True`` if you want silent failure for missing
+                       files.
+        :return: bool. ``True`` if able to load config, ``False`` otherwise.
+        """
+        rv = os.environ.get(variable_name)
+        if not rv:
+            if silent:
+                return False
+            raise RuntimeError('The environment variable %r is not set '
+                               'and as such configuration could not be '
+                               'loaded.  Set this variable and make it '
+                               'point to a configuration file' %
+                               variable_name)
+        return self.from_pyfile(rv, silent=silent)
+
+    def from_pyfile(self, filename, silent=False):
+        """Updates the values in the config from a Python file.  This function
+        behaves as if the file was imported as module with the
+        :meth:`from_object` function.
+
+        :param filename: the filename of the config.  This can either be an
+                         absolute filename or a filename relative to the
+                         root path.
+        :param silent: set to ``True`` if you want silent failure for missing
+                       files.
+
+        .. versionadded:: 0.7
+           `silent` parameter.
+        """
+        filename = os.path.join(self.root_path, filename)
+        d = types.ModuleType('config')
+        d.__file__ = filename
+        try:
+            with open(filename, mode='rb') as config_file:
+                exec(compile(config_file.read(), filename, 'exec'), d.__dict__)
+        except IOError as e:
+            if silent and e.errno in (
+                errno.ENOENT, errno.EISDIR, errno.ENOTDIR
+            ):
+                return False
+            e.strerror = 'Unable to load configuration file (%s)' % e.strerror
+            raise
+        self.from_object(d)
+        return True
+
+    def from_object(self, obj):
+        """Updates the values from the given object.  An object can be of one
+        of the following two types:
+
+        -   a string: in this case the object with that name will be imported
+        -   an actual object reference: that object is used directly
+
+        Objects are usually either modules or classes. :meth:`from_object`
+        loads only the uppercase attributes of the module/class. A ``dict``
+        object will not work with :meth:`from_object` because the keys of a
+        ``dict`` are not attributes of the ``dict`` class.
+
+        Example of module-based configuration::
+
+            app.config.from_object('yourapplication.default_config')
+            from yourapplication import default_config
+            app.config.from_object(default_config)
+
+        Nothing is done to the object before loading. If the object is a
+        class and has ``@property`` attributes, it needs to be
+        instantiated before being passed to this method.
+
+        You should not use this function to load the actual configuration but
+        rather configuration defaults.  The actual config should be loaded
+        with :meth:`from_pyfile` and ideally from a location not within the
+        package because the package might be installed system wide.
+
+        See :ref:`config-dev-prod` for an example of class-based configuration
+        using :meth:`from_object`.
+
+        :param obj: an import name or object
+        """
+        if isinstance(obj, string_types):
+            obj = import_string(obj)
+        for key in dir(obj):
+            if key.isupper():
+                self[key] = getattr(obj, key)
+
+    def from_json(self, filename, silent=False):
+        """Updates the values in the config from a JSON file. This function
+        behaves as if the JSON object was a dictionary and passed to the
+        :meth:`from_mapping` function.
+
+        :param filename: the filename of the JSON file.  This can either be an
+                         absolute filename or a filename relative to the
+                         root path.
+        :param silent: set to ``True`` if you want silent failure for missing
+                       files.
+
+        .. versionadded:: 0.11
+        """
+        filename = os.path.join(self.root_path, filename)
+
+        try:
+            with open(filename) as json_file:
+                obj = json.loads(json_file.read())
+        except IOError as e:
+            if silent and e.errno in (errno.ENOENT, errno.EISDIR):
+                return False
+            e.strerror = 'Unable to load configuration file (%s)' % e.strerror
+            raise
+        return self.from_mapping(obj)
+
+    def from_mapping(self, *mapping, **kwargs):
+        """Updates the config like :meth:`update` ignoring items with non-upper
+        keys.
+
+        .. versionadded:: 0.11
+        """
+        mappings = []
+        if len(mapping) == 1:
+            if hasattr(mapping[0], 'items'):
+                mappings.append(mapping[0].items())
+            else:
+                mappings.append(mapping[0])
+        elif len(mapping) > 1:
+            raise TypeError(
+                'expected at most 1 positional argument, got %d' % len(mapping)
+            )
+        mappings.append(kwargs.items())
+        for mapping in mappings:
+            for (key, value) in mapping:
+                if key.isupper():
+                    self[key] = value
+        return True
+
+    def get_namespace(self, namespace, lowercase=True, trim_namespace=True):
+        """Returns a dictionary containing a subset of configuration options
+        that match the specified namespace/prefix. Example usage::
+
+            app.config['IMAGE_STORE_TYPE'] = 'fs'
+            app.config['IMAGE_STORE_PATH'] = '/var/app/images'
+            app.config['IMAGE_STORE_BASE_URL'] = 'http://img.website.com'
+            image_store_config = app.config.get_namespace('IMAGE_STORE_')
+
+        The resulting dictionary `image_store_config` would look like::
+
+            {
+                'type': 'fs',
+                'path': '/var/app/images',
+                'base_url': 'http://img.website.com'
+            }
+
+        This is often useful when configuration options map directly to
+        keyword arguments in functions or class constructors.
+
+        :param namespace: a configuration namespace
+        :param lowercase: a flag indicating if the keys of the resulting
+                          dictionary should be lowercase
+        :param trim_namespace: a flag indicating if the keys of the resulting
+                          dictionary should not include the namespace
+
+        .. versionadded:: 0.11
+        """
+        rv = {}
+        for k, v in iteritems(self):
+            if not k.startswith(namespace):
+                continue
+            if trim_namespace:
+                key = k[len(namespace):]
+            else:
+                key = k
+            if lowercase:
+                key = key.lower()
+            rv[key] = v
+        return rv
+
+    def __repr__(self):
+        return '<%s %s>' % (self.__class__.__name__, dict.__repr__(self))
diff --git a/python/flask/ctx.py b/python/flask/ctx.py
new file mode 100644
index 0000000..ec8e787
--- /dev/null
+++ b/python/flask/ctx.py
@@ -0,0 +1,457 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.ctx
+    ~~~~~~~~~
+
+    Implements the objects required to keep the context.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import sys
+from functools import update_wrapper
+
+from werkzeug.exceptions import HTTPException
+
+from .globals import _request_ctx_stack, _app_ctx_stack
+from .signals import appcontext_pushed, appcontext_popped
+from ._compat import BROKEN_PYPY_CTXMGR_EXIT, reraise
+
+
+# a singleton sentinel value for parameter defaults
+_sentinel = object()
+
+
+class _AppCtxGlobals(object):
+    """A plain object. Used as a namespace for storing data during an
+    application context.
+
+    Creating an app context automatically creates this object, which is
+    made available as the :data:`g` proxy.
+
+    .. describe:: 'key' in g
+
+        Check whether an attribute is present.
+
+        .. versionadded:: 0.10
+
+    .. describe:: iter(g)
+
+        Return an iterator over the attribute names.
+
+        .. versionadded:: 0.10
+    """
+
+    def get(self, name, default=None):
+        """Get an attribute by name, or a default value. Like
+        :meth:`dict.get`.
+
+        :param name: Name of attribute to get.
+        :param default: Value to return if the attribute is not present.
+
+        .. versionadded:: 0.10
+        """
+        return self.__dict__.get(name, default)
+
+    def pop(self, name, default=_sentinel):
+        """Get and remove an attribute by name. Like :meth:`dict.pop`.
+
+        :param name: Name of attribute to pop.
+        :param default: Value to return if the attribute is not present,
+            instead of raise a ``KeyError``.
+
+        .. versionadded:: 0.11
+        """
+        if default is _sentinel:
+            return self.__dict__.pop(name)
+        else:
+            return self.__dict__.pop(name, default)
+
+    def setdefault(self, name, default=None):
+        """Get the value of an attribute if it is present, otherwise
+        set and return a default value. Like :meth:`dict.setdefault`.
+
+        :param name: Name of attribute to get.
+        :param: default: Value to set and return if the attribute is not
+            present.
+
+        .. versionadded:: 0.11
+        """
+        return self.__dict__.setdefault(name, default)
+
+    def __contains__(self, item):
+        return item in self.__dict__
+
+    def __iter__(self):
+        return iter(self.__dict__)
+
+    def __repr__(self):
+        top = _app_ctx_stack.top
+        if top is not None:
+            return '<flask.g of %r>' % top.app.name
+        return object.__repr__(self)
+
+
+def after_this_request(f):
+    """Executes a function after this request.  This is useful to modify
+    response objects.  The function is passed the response object and has
+    to return the same or a new one.
+
+    Example::
+
+        @app.route('/')
+        def index():
+            @after_this_request
+            def add_header(response):
+                response.headers['X-Foo'] = 'Parachute'
+                return response
+            return 'Hello World!'
+
+    This is more useful if a function other than the view function wants to
+    modify a response.  For instance think of a decorator that wants to add
+    some headers without converting the return value into a response object.
+
+    .. versionadded:: 0.9
+    """
+    _request_ctx_stack.top._after_request_functions.append(f)
+    return f
+
+
+def copy_current_request_context(f):
+    """A helper function that decorates a function to retain the current
+    request context.  This is useful when working with greenlets.  The moment
+    the function is decorated a copy of the request context is created and
+    then pushed when the function is called.
+
+    Example::
+
+        import gevent
+        from flask import copy_current_request_context
+
+        @app.route('/')
+        def index():
+            @copy_current_request_context
+            def do_some_work():
+                # do some work here, it can access flask.request like you
+                # would otherwise in the view function.
+                ...
+            gevent.spawn(do_some_work)
+            return 'Regular response'
+
+    .. versionadded:: 0.10
+    """
+    top = _request_ctx_stack.top
+    if top is None:
+        raise RuntimeError('This decorator can only be used at local scopes '
+            'when a request context is on the stack.  For instance within '
+            'view functions.')
+    reqctx = top.copy()
+    def wrapper(*args, **kwargs):
+        with reqctx:
+            return f(*args, **kwargs)
+    return update_wrapper(wrapper, f)
+
+
+def has_request_context():
+    """If you have code that wants to test if a request context is there or
+    not this function can be used.  For instance, you may want to take advantage
+    of request information if the request object is available, but fail
+    silently if it is unavailable.
+
+    ::
+
+        class User(db.Model):
+
+            def __init__(self, username, remote_addr=None):
+                self.username = username
+                if remote_addr is None and has_request_context():
+                    remote_addr = request.remote_addr
+                self.remote_addr = remote_addr
+
+    Alternatively you can also just test any of the context bound objects
+    (such as :class:`request` or :class:`g`) for truthness::
+
+        class User(db.Model):
+
+            def __init__(self, username, remote_addr=None):
+                self.username = username
+                if remote_addr is None and request:
+                    remote_addr = request.remote_addr
+                self.remote_addr = remote_addr
+
+    .. versionadded:: 0.7
+    """
+    return _request_ctx_stack.top is not None
+
+
+def has_app_context():
+    """Works like :func:`has_request_context` but for the application
+    context.  You can also just do a boolean check on the
+    :data:`current_app` object instead.
+
+    .. versionadded:: 0.9
+    """
+    return _app_ctx_stack.top is not None
+
+
+class AppContext(object):
+    """The application context binds an application object implicitly
+    to the current thread or greenlet, similar to how the
+    :class:`RequestContext` binds request information.  The application
+    context is also implicitly created if a request context is created
+    but the application is not on top of the individual application
+    context.
+    """
+
+    def __init__(self, app):
+        self.app = app
+        self.url_adapter = app.create_url_adapter(None)
+        self.g = app.app_ctx_globals_class()
+
+        # Like request context, app contexts can be pushed multiple times
+        # but there a basic "refcount" is enough to track them.
+        self._refcnt = 0
+
+    def push(self):
+        """Binds the app context to the current context."""
+        self._refcnt += 1
+        if hasattr(sys, 'exc_clear'):
+            sys.exc_clear()
+        _app_ctx_stack.push(self)
+        appcontext_pushed.send(self.app)
+
+    def pop(self, exc=_sentinel):
+        """Pops the app context."""
+        try:
+            self._refcnt -= 1
+            if self._refcnt <= 0:
+                if exc is _sentinel:
+                    exc = sys.exc_info()[1]
+                self.app.do_teardown_appcontext(exc)
+        finally:
+            rv = _app_ctx_stack.pop()
+        assert rv is self, 'Popped wrong app context.  (%r instead of %r)' \
+            % (rv, self)
+        appcontext_popped.send(self.app)
+
+    def __enter__(self):
+        self.push()
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.pop(exc_value)
+
+        if BROKEN_PYPY_CTXMGR_EXIT and exc_type is not None:
+            reraise(exc_type, exc_value, tb)
+
+
+class RequestContext(object):
+    """The request context contains all request relevant information.  It is
+    created at the beginning of the request and pushed to the
+    `_request_ctx_stack` and removed at the end of it.  It will create the
+    URL adapter and request object for the WSGI environment provided.
+
+    Do not attempt to use this class directly, instead use
+    :meth:`~flask.Flask.test_request_context` and
+    :meth:`~flask.Flask.request_context` to create this object.
+
+    When the request context is popped, it will evaluate all the
+    functions registered on the application for teardown execution
+    (:meth:`~flask.Flask.teardown_request`).
+
+    The request context is automatically popped at the end of the request
+    for you.  In debug mode the request context is kept around if
+    exceptions happen so that interactive debuggers have a chance to
+    introspect the data.  With 0.4 this can also be forced for requests
+    that did not fail and outside of ``DEBUG`` mode.  By setting
+    ``'flask._preserve_context'`` to ``True`` on the WSGI environment the
+    context will not pop itself at the end of the request.  This is used by
+    the :meth:`~flask.Flask.test_client` for example to implement the
+    deferred cleanup functionality.
+
+    You might find this helpful for unittests where you need the
+    information from the context local around for a little longer.  Make
+    sure to properly :meth:`~werkzeug.LocalStack.pop` the stack yourself in
+    that situation, otherwise your unittests will leak memory.
+    """
+
+    def __init__(self, app, environ, request=None):
+        self.app = app
+        if request is None:
+            request = app.request_class(environ)
+        self.request = request
+        self.url_adapter = app.create_url_adapter(self.request)
+        self.flashes = None
+        self.session = None
+
+        # Request contexts can be pushed multiple times and interleaved with
+        # other request contexts.  Now only if the last level is popped we
+        # get rid of them.  Additionally if an application context is missing
+        # one is created implicitly so for each level we add this information
+        self._implicit_app_ctx_stack = []
+
+        # indicator if the context was preserved.  Next time another context
+        # is pushed the preserved context is popped.
+        self.preserved = False
+
+        # remembers the exception for pop if there is one in case the context
+        # preservation kicks in.
+        self._preserved_exc = None
+
+        # Functions that should be executed after the request on the response
+        # object.  These will be called before the regular "after_request"
+        # functions.
+        self._after_request_functions = []
+
+        self.match_request()
+
+    def _get_g(self):
+        return _app_ctx_stack.top.g
+    def _set_g(self, value):
+        _app_ctx_stack.top.g = value
+    g = property(_get_g, _set_g)
+    del _get_g, _set_g
+
+    def copy(self):
+        """Creates a copy of this request context with the same request object.
+        This can be used to move a request context to a different greenlet.
+        Because the actual request object is the same this cannot be used to
+        move a request context to a different thread unless access to the
+        request object is locked.
+
+        .. versionadded:: 0.10
+        """
+        return self.__class__(self.app,
+            environ=self.request.environ,
+            request=self.request
+        )
+
+    def match_request(self):
+        """Can be overridden by a subclass to hook into the matching
+        of the request.
+        """
+        try:
+            url_rule, self.request.view_args = \
+                self.url_adapter.match(return_rule=True)
+            self.request.url_rule = url_rule
+        except HTTPException as e:
+            self.request.routing_exception = e
+
+    def push(self):
+        """Binds the request context to the current context."""
+        # If an exception occurs in debug mode or if context preservation is
+        # activated under exception situations exactly one context stays
+        # on the stack.  The rationale is that you want to access that
+        # information under debug situations.  However if someone forgets to
+        # pop that context again we want to make sure that on the next push
+        # it's invalidated, otherwise we run at risk that something leaks
+        # memory.  This is usually only a problem in test suite since this
+        # functionality is not active in production environments.
+        top = _request_ctx_stack.top
+        if top is not None and top.preserved:
+            top.pop(top._preserved_exc)
+
+        # Before we push the request context we have to ensure that there
+        # is an application context.
+        app_ctx = _app_ctx_stack.top
+        if app_ctx is None or app_ctx.app != self.app:
+            app_ctx = self.app.app_context()
+            app_ctx.push()
+            self._implicit_app_ctx_stack.append(app_ctx)
+        else:
+            self._implicit_app_ctx_stack.append(None)
+
+        if hasattr(sys, 'exc_clear'):
+            sys.exc_clear()
+
+        _request_ctx_stack.push(self)
+
+        # Open the session at the moment that the request context is available.
+        # This allows a custom open_session method to use the request context.
+        # Only open a new session if this is the first time the request was
+        # pushed, otherwise stream_with_context loses the session.
+        if self.session is None:
+            session_interface = self.app.session_interface
+            self.session = session_interface.open_session(
+                self.app, self.request
+            )
+
+            if self.session is None:
+                self.session = session_interface.make_null_session(self.app)
+
+    def pop(self, exc=_sentinel):
+        """Pops the request context and unbinds it by doing that.  This will
+        also trigger the execution of functions registered by the
+        :meth:`~flask.Flask.teardown_request` decorator.
+
+        .. versionchanged:: 0.9
+           Added the `exc` argument.
+        """
+        app_ctx = self._implicit_app_ctx_stack.pop()
+
+        try:
+            clear_request = False
+            if not self._implicit_app_ctx_stack:
+                self.preserved = False
+                self._preserved_exc = None
+                if exc is _sentinel:
+                    exc = sys.exc_info()[1]
+                self.app.do_teardown_request(exc)
+
+                # If this interpreter supports clearing the exception information
+                # we do that now.  This will only go into effect on Python 2.x,
+                # on 3.x it disappears automatically at the end of the exception
+                # stack.
+                if hasattr(sys, 'exc_clear'):
+                    sys.exc_clear()
+
+                request_close = getattr(self.request, 'close', None)
+                if request_close is not None:
+                    request_close()
+                clear_request = True
+        finally:
+            rv = _request_ctx_stack.pop()
+
+            # get rid of circular dependencies at the end of the request
+            # so that we don't require the GC to be active.
+            if clear_request:
+                rv.request.environ['werkzeug.request'] = None
+
+            # Get rid of the app as well if necessary.
+            if app_ctx is not None:
+                app_ctx.pop(exc)
+
+            assert rv is self, 'Popped wrong request context.  ' \
+                '(%r instead of %r)' % (rv, self)
+
+    def auto_pop(self, exc):
+        if self.request.environ.get('flask._preserve_context') or \
+           (exc is not None and self.app.preserve_context_on_exception):
+            self.preserved = True
+            self._preserved_exc = exc
+        else:
+            self.pop(exc)
+
+    def __enter__(self):
+        self.push()
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        # do not pop the request stack if we are in debug mode and an
+        # exception happened.  This will allow the debugger to still
+        # access the request object in the interactive shell.  Furthermore
+        # the context can be force kept alive for the test client.
+        # See flask.testing for how this works.
+        self.auto_pop(exc_value)
+
+        if BROKEN_PYPY_CTXMGR_EXIT and exc_type is not None:
+            reraise(exc_type, exc_value, tb)
+
+    def __repr__(self):
+        return '<%s \'%s\' [%s] of %s>' % (
+            self.__class__.__name__,
+            self.request.url,
+            self.request.method,
+            self.app.name,
+        )
diff --git a/python/flask/debughelpers.py b/python/flask/debughelpers.py
new file mode 100644
index 0000000..e9765f2
--- /dev/null
+++ b/python/flask/debughelpers.py
@@ -0,0 +1,168 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.debughelpers
+    ~~~~~~~~~~~~~~~~~~
+
+    Various helpers to make the development experience better.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import os
+from warnings import warn
+
+from ._compat import implements_to_string, text_type
+from .app import Flask
+from .blueprints import Blueprint
+from .globals import _request_ctx_stack
+
+
+class UnexpectedUnicodeError(AssertionError, UnicodeError):
+    """Raised in places where we want some better error reporting for
+    unexpected unicode or binary data.
+    """
+
+
+@implements_to_string
+class DebugFilesKeyError(KeyError, AssertionError):
+    """Raised from request.files during debugging.  The idea is that it can
+    provide a better error message than just a generic KeyError/BadRequest.
+    """
+
+    def __init__(self, request, key):
+        form_matches = request.form.getlist(key)
+        buf = ['You tried to access the file "%s" in the request.files '
+               'dictionary but it does not exist.  The mimetype for the request '
+               'is "%s" instead of "multipart/form-data" which means that no '
+               'file contents were transmitted.  To fix this error you should '
+               'provide enctype="multipart/form-data" in your form.' %
+               (key, request.mimetype)]
+        if form_matches:
+            buf.append('\n\nThe browser instead transmitted some file names. '
+                       'This was submitted: %s' % ', '.join('"%s"' % x
+                            for x in form_matches))
+        self.msg = ''.join(buf)
+
+    def __str__(self):
+        return self.msg
+
+
+class FormDataRoutingRedirect(AssertionError):
+    """This exception is raised by Flask in debug mode if it detects a
+    redirect caused by the routing system when the request method is not
+    GET, HEAD or OPTIONS.  Reasoning: form data will be dropped.
+    """
+
+    def __init__(self, request):
+        exc = request.routing_exception
+        buf = ['A request was sent to this URL (%s) but a redirect was '
+               'issued automatically by the routing system to "%s".'
+               % (request.url, exc.new_url)]
+
+        # In case just a slash was appended we can be extra helpful
+        if request.base_url + '/' == exc.new_url.split('?')[0]:
+            buf.append('  The URL was defined with a trailing slash so '
+                       'Flask will automatically redirect to the URL '
+                       'with the trailing slash if it was accessed '
+                       'without one.')
+
+        buf.append('  Make sure to directly send your %s-request to this URL '
+                   'since we can\'t make browsers or HTTP clients redirect '
+                   'with form data reliably or without user interaction.' %
+                   request.method)
+        buf.append('\n\nNote: this exception is only raised in debug mode')
+        AssertionError.__init__(self, ''.join(buf).encode('utf-8'))
+
+
+def attach_enctype_error_multidict(request):
+    """Since Flask 0.8 we're monkeypatching the files object in case a
+    request is detected that does not use multipart form data but the files
+    object is accessed.
+    """
+    oldcls = request.files.__class__
+    class newcls(oldcls):
+        def __getitem__(self, key):
+            try:
+                return oldcls.__getitem__(self, key)
+            except KeyError:
+                if key not in request.form:
+                    raise
+                raise DebugFilesKeyError(request, key)
+    newcls.__name__ = oldcls.__name__
+    newcls.__module__ = oldcls.__module__
+    request.files.__class__ = newcls
+
+
+def _dump_loader_info(loader):
+    yield 'class: %s.%s' % (type(loader).__module__, type(loader).__name__)
+    for key, value in sorted(loader.__dict__.items()):
+        if key.startswith('_'):
+            continue
+        if isinstance(value, (tuple, list)):
+            if not all(isinstance(x, (str, text_type)) for x in value):
+                continue
+            yield '%s:' % key
+            for item in value:
+                yield '  - %s' % item
+            continue
+        elif not isinstance(value, (str, text_type, int, float, bool)):
+            continue
+        yield '%s: %r' % (key, value)
+
+
+def explain_template_loading_attempts(app, template, attempts):
+    """This should help developers understand what failed"""
+    info = ['Locating template "%s":' % template]
+    total_found = 0
+    blueprint = None
+    reqctx = _request_ctx_stack.top
+    if reqctx is not None and reqctx.request.blueprint is not None:
+        blueprint = reqctx.request.blueprint
+
+    for idx, (loader, srcobj, triple) in enumerate(attempts):
+        if isinstance(srcobj, Flask):
+            src_info = 'application "%s"' % srcobj.import_name
+        elif isinstance(srcobj, Blueprint):
+            src_info = 'blueprint "%s" (%s)' % (srcobj.name,
+                                                srcobj.import_name)
+        else:
+            src_info = repr(srcobj)
+
+        info.append('% 5d: trying loader of %s' % (
+            idx + 1, src_info))
+
+        for line in _dump_loader_info(loader):
+            info.append('       %s' % line)
+
+        if triple is None:
+            detail = 'no match'
+        else:
+            detail = 'found (%r)' % (triple[1] or '<string>')
+            total_found += 1
+        info.append('       -> %s' % detail)
+
+    seems_fishy = False
+    if total_found == 0:
+        info.append('Error: the template could not be found.')
+        seems_fishy = True
+    elif total_found > 1:
+        info.append('Warning: multiple loaders returned a match for the template.')
+        seems_fishy = True
+
+    if blueprint is not None and seems_fishy:
+        info.append('  The template was looked up from an endpoint that '
+                    'belongs to the blueprint "%s".' % blueprint)
+        info.append('  Maybe you did not place a template in the right folder?')
+        info.append('  See http://flask.pocoo.org/docs/blueprints/#templates')
+
+    app.logger.info('\n'.join(info))
+
+
+def explain_ignored_app_run():
+    if os.environ.get('WERKZEUG_RUN_MAIN') != 'true':
+        warn(Warning('Silently ignoring app.run() because the '
+                     'application is run from the flask command line '
+                     'executable.  Consider putting app.run() behind an '
+                     'if __name__ == "__main__" guard to silence this '
+                     'warning.'), stacklevel=3)
diff --git a/python/flask/globals.py b/python/flask/globals.py
new file mode 100644
index 0000000..7d50a6f
--- /dev/null
+++ b/python/flask/globals.py
@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.globals
+    ~~~~~~~~~~~~~
+
+    Defines all the global objects that are proxies to the current
+    active context.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from functools import partial
+from werkzeug.local import LocalStack, LocalProxy
+
+
+_request_ctx_err_msg = '''\
+Working outside of request context.
+
+This typically means that you attempted to use functionality that needed
+an active HTTP request.  Consult the documentation on testing for
+information about how to avoid this problem.\
+'''
+_app_ctx_err_msg = '''\
+Working outside of application context.
+
+This typically means that you attempted to use functionality that needed
+to interface with the current application object in some way. To solve
+this, set up an application context with app.app_context().  See the
+documentation for more information.\
+'''
+
+
+def _lookup_req_object(name):
+    top = _request_ctx_stack.top
+    if top is None:
+        raise RuntimeError(_request_ctx_err_msg)
+    return getattr(top, name)
+
+
+def _lookup_app_object(name):
+    top = _app_ctx_stack.top
+    if top is None:
+        raise RuntimeError(_app_ctx_err_msg)
+    return getattr(top, name)
+
+
+def _find_app():
+    top = _app_ctx_stack.top
+    if top is None:
+        raise RuntimeError(_app_ctx_err_msg)
+    return top.app
+
+
+# context locals
+_request_ctx_stack = LocalStack()
+_app_ctx_stack = LocalStack()
+current_app = LocalProxy(_find_app)
+request = LocalProxy(partial(_lookup_req_object, 'request'))
+session = LocalProxy(partial(_lookup_req_object, 'session'))
+g = LocalProxy(partial(_lookup_app_object, 'g'))
diff --git a/python/flask/helpers.py b/python/flask/helpers.py
new file mode 100644
index 0000000..158edc5
--- /dev/null
+++ b/python/flask/helpers.py
@@ -0,0 +1,1051 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.helpers
+    ~~~~~~~~~~~~~
+
+    Implements various helpers.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import os
+import socket
+import sys
+import pkgutil
+import posixpath
+import mimetypes
+from time import time
+from zlib import adler32
+from threading import RLock
+import unicodedata
+from werkzeug.routing import BuildError
+from functools import update_wrapper
+
+from werkzeug.urls import url_quote
+from werkzeug.datastructures import Headers, Range
+from werkzeug.exceptions import BadRequest, NotFound, \
+    RequestedRangeNotSatisfiable
+
+from werkzeug.wsgi import wrap_file
+from jinja2 import FileSystemLoader
+
+from .signals import message_flashed
+from .globals import session, _request_ctx_stack, _app_ctx_stack, \
+     current_app, request
+from ._compat import string_types, text_type, PY2
+
+# sentinel
+_missing = object()
+
+
+# what separators does this operating system provide that are not a slash?
+# this is used by the send_from_directory function to ensure that nobody is
+# able to access files from outside the filesystem.
+_os_alt_seps = list(sep for sep in [os.path.sep, os.path.altsep]
+                    if sep not in (None, '/'))
+
+
+def get_env():
+    """Get the environment the app is running in, indicated by the
+    :envvar:`FLASK_ENV` environment variable. The default is
+    ``'production'``.
+    """
+    return os.environ.get('FLASK_ENV') or 'production'
+
+
+def get_debug_flag():
+    """Get whether debug mode should be enabled for the app, indicated
+    by the :envvar:`FLASK_DEBUG` environment variable. The default is
+    ``True`` if :func:`.get_env` returns ``'development'``, or ``False``
+    otherwise.
+    """
+    val = os.environ.get('FLASK_DEBUG')
+
+    if not val:
+        return get_env() == 'development'
+
+    return val.lower() not in ('0', 'false', 'no')
+
+
+def get_load_dotenv(default=True):
+    """Get whether the user has disabled loading dotenv files by setting
+    :envvar:`FLASK_SKIP_DOTENV`. The default is ``True``, load the
+    files.
+
+    :param default: What to return if the env var isn't set.
+    """
+    val = os.environ.get('FLASK_SKIP_DOTENV')
+
+    if not val:
+        return default
+
+    return val.lower() in ('0', 'false', 'no')
+
+
+def _endpoint_from_view_func(view_func):
+    """Internal helper that returns the default endpoint for a given
+    function.  This always is the function name.
+    """
+    assert view_func is not None, 'expected view func if endpoint ' \
+                                  'is not provided.'
+    return view_func.__name__
+
+
+def stream_with_context(generator_or_function):
+    """Request contexts disappear when the response is started on the server.
+    This is done for efficiency reasons and to make it less likely to encounter
+    memory leaks with badly written WSGI middlewares.  The downside is that if
+    you are using streamed responses, the generator cannot access request bound
+    information any more.
+
+    This function however can help you keep the context around for longer::
+
+        from flask import stream_with_context, request, Response
+
+        @app.route('/stream')
+        def streamed_response():
+            @stream_with_context
+            def generate():
+                yield 'Hello '
+                yield request.args['name']
+                yield '!'
+            return Response(generate())
+
+    Alternatively it can also be used around a specific generator::
+
+        from flask import stream_with_context, request, Response
+
+        @app.route('/stream')
+        def streamed_response():
+            def generate():
+                yield 'Hello '
+                yield request.args['name']
+                yield '!'
+            return Response(stream_with_context(generate()))
+
+    .. versionadded:: 0.9
+    """
+    try:
+        gen = iter(generator_or_function)
+    except TypeError:
+        def decorator(*args, **kwargs):
+            gen = generator_or_function(*args, **kwargs)
+            return stream_with_context(gen)
+        return update_wrapper(decorator, generator_or_function)
+
+    def generator():
+        ctx = _request_ctx_stack.top
+        if ctx is None:
+            raise RuntimeError('Attempted to stream with context but '
+                'there was no context in the first place to keep around.')
+        with ctx:
+            # Dummy sentinel.  Has to be inside the context block or we're
+            # not actually keeping the context around.
+            yield None
+
+            # The try/finally is here so that if someone passes a WSGI level
+            # iterator in we're still running the cleanup logic.  Generators
+            # don't need that because they are closed on their destruction
+            # automatically.
+            try:
+                for item in gen:
+                    yield item
+            finally:
+                if hasattr(gen, 'close'):
+                    gen.close()
+
+    # The trick is to start the generator.  Then the code execution runs until
+    # the first dummy None is yielded at which point the context was already
+    # pushed.  This item is discarded.  Then when the iteration continues the
+    # real generator is executed.
+    wrapped_g = generator()
+    next(wrapped_g)
+    return wrapped_g
+
+
+def make_response(*args):
+    """Sometimes it is necessary to set additional headers in a view.  Because
+    views do not have to return response objects but can return a value that
+    is converted into a response object by Flask itself, it becomes tricky to
+    add headers to it.  This function can be called instead of using a return
+    and you will get a response object which you can use to attach headers.
+
+    If view looked like this and you want to add a new header::
+
+        def index():
+            return render_template('index.html', foo=42)
+
+    You can now do something like this::
+
+        def index():
+            response = make_response(render_template('index.html', foo=42))
+            response.headers['X-Parachutes'] = 'parachutes are cool'
+            return response
+
+    This function accepts the very same arguments you can return from a
+    view function.  This for example creates a response with a 404 error
+    code::
+
+        response = make_response(render_template('not_found.html'), 404)
+
+    The other use case of this function is to force the return value of a
+    view function into a response which is helpful with view
+    decorators::
+
+        response = make_response(view_function())
+        response.headers['X-Parachutes'] = 'parachutes are cool'
+
+    Internally this function does the following things:
+
+    -   if no arguments are passed, it creates a new response argument
+    -   if one argument is passed, :meth:`flask.Flask.make_response`
+        is invoked with it.
+    -   if more than one argument is passed, the arguments are passed
+        to the :meth:`flask.Flask.make_response` function as tuple.
+
+    .. versionadded:: 0.6
+    """
+    if not args:
+        return current_app.response_class()
+    if len(args) == 1:
+        args = args[0]
+    return current_app.make_response(args)
+
+
+def url_for(endpoint, **values):
+    """Generates a URL to the given endpoint with the method provided.
+
+    Variable arguments that are unknown to the target endpoint are appended
+    to the generated URL as query arguments.  If the value of a query argument
+    is ``None``, the whole pair is skipped.  In case blueprints are active
+    you can shortcut references to the same blueprint by prefixing the
+    local endpoint with a dot (``.``).
+
+    This will reference the index function local to the current blueprint::
+
+        url_for('.index')
+
+    For more information, head over to the :ref:`Quickstart <url-building>`.
+
+    To integrate applications, :class:`Flask` has a hook to intercept URL build
+    errors through :attr:`Flask.url_build_error_handlers`.  The `url_for`
+    function results in a :exc:`~werkzeug.routing.BuildError` when the current
+    app does not have a URL for the given endpoint and values.  When it does, the
+    :data:`~flask.current_app` calls its :attr:`~Flask.url_build_error_handlers` if
+    it is not ``None``, which can return a string to use as the result of
+    `url_for` (instead of `url_for`'s default to raise the
+    :exc:`~werkzeug.routing.BuildError` exception) or re-raise the exception.
+    An example::
+
+        def external_url_handler(error, endpoint, values):
+            "Looks up an external URL when `url_for` cannot build a URL."
+            # This is an example of hooking the build_error_handler.
+            # Here, lookup_url is some utility function you've built
+            # which looks up the endpoint in some external URL registry.
+            url = lookup_url(endpoint, **values)
+            if url is None:
+                # External lookup did not have a URL.
+                # Re-raise the BuildError, in context of original traceback.
+                exc_type, exc_value, tb = sys.exc_info()
+                if exc_value is error:
+                    raise exc_type, exc_value, tb
+                else:
+                    raise error
+            # url_for will use this result, instead of raising BuildError.
+            return url
+
+        app.url_build_error_handlers.append(external_url_handler)
+
+    Here, `error` is the instance of :exc:`~werkzeug.routing.BuildError`, and
+    `endpoint` and `values` are the arguments passed into `url_for`.  Note
+    that this is for building URLs outside the current application, and not for
+    handling 404 NotFound errors.
+
+    .. versionadded:: 0.10
+       The `_scheme` parameter was added.
+
+    .. versionadded:: 0.9
+       The `_anchor` and `_method` parameters were added.
+
+    .. versionadded:: 0.9
+       Calls :meth:`Flask.handle_build_error` on
+       :exc:`~werkzeug.routing.BuildError`.
+
+    :param endpoint: the endpoint of the URL (name of the function)
+    :param values: the variable arguments of the URL rule
+    :param _external: if set to ``True``, an absolute URL is generated. Server
+      address can be changed via ``SERVER_NAME`` configuration variable which
+      falls back to the `Host` header, then to the IP and port of the request.
+    :param _scheme: a string specifying the desired URL scheme. The `_external`
+      parameter must be set to ``True`` or a :exc:`ValueError` is raised. The default
+      behavior uses the same scheme as the current request, or
+      ``PREFERRED_URL_SCHEME`` from the :ref:`app configuration <config>` if no
+      request context is available. As of Werkzeug 0.10, this also can be set
+      to an empty string to build protocol-relative URLs.
+    :param _anchor: if provided this is added as anchor to the URL.
+    :param _method: if provided this explicitly specifies an HTTP method.
+    """
+    appctx = _app_ctx_stack.top
+    reqctx = _request_ctx_stack.top
+
+    if appctx is None:
+        raise RuntimeError(
+            'Attempted to generate a URL without the application context being'
+            ' pushed. This has to be executed when application context is'
+            ' available.'
+        )
+
+    # If request specific information is available we have some extra
+    # features that support "relative" URLs.
+    if reqctx is not None:
+        url_adapter = reqctx.url_adapter
+        blueprint_name = request.blueprint
+
+        if endpoint[:1] == '.':
+            if blueprint_name is not None:
+                endpoint = blueprint_name + endpoint
+            else:
+                endpoint = endpoint[1:]
+
+        external = values.pop('_external', False)
+
+    # Otherwise go with the url adapter from the appctx and make
+    # the URLs external by default.
+    else:
+        url_adapter = appctx.url_adapter
+
+        if url_adapter is None:
+            raise RuntimeError(
+                'Application was not able to create a URL adapter for request'
+                ' independent URL generation. You might be able to fix this by'
+                ' setting the SERVER_NAME config variable.'
+            )
+
+        external = values.pop('_external', True)
+
+    anchor = values.pop('_anchor', None)
+    method = values.pop('_method', None)
+    scheme = values.pop('_scheme', None)
+    appctx.app.inject_url_defaults(endpoint, values)
+
+    # This is not the best way to deal with this but currently the
+    # underlying Werkzeug router does not support overriding the scheme on
+    # a per build call basis.
+    old_scheme = None
+    if scheme is not None:
+        if not external:
+            raise ValueError('When specifying _scheme, _external must be True')
+        old_scheme = url_adapter.url_scheme
+        url_adapter.url_scheme = scheme
+
+    try:
+        try:
+            rv = url_adapter.build(endpoint, values, method=method,
+                                   force_external=external)
+        finally:
+            if old_scheme is not None:
+                url_adapter.url_scheme = old_scheme
+    except BuildError as error:
+        # We need to inject the values again so that the app callback can
+        # deal with that sort of stuff.
+        values['_external'] = external
+        values['_anchor'] = anchor
+        values['_method'] = method
+        values['_scheme'] = scheme
+        return appctx.app.handle_url_build_error(error, endpoint, values)
+
+    if anchor is not None:
+        rv += '#' + url_quote(anchor)
+    return rv
+
+
+def get_template_attribute(template_name, attribute):
+    """Loads a macro (or variable) a template exports.  This can be used to
+    invoke a macro from within Python code.  If you for example have a
+    template named :file:`_cider.html` with the following contents:
+
+    .. sourcecode:: html+jinja
+
+       {% macro hello(name) %}Hello {{ name }}!{% endmacro %}
+
+    You can access this from Python code like this::
+
+        hello = get_template_attribute('_cider.html', 'hello')
+        return hello('World')
+
+    .. versionadded:: 0.2
+
+    :param template_name: the name of the template
+    :param attribute: the name of the variable of macro to access
+    """
+    return getattr(current_app.jinja_env.get_template(template_name).module,
+                   attribute)
+
+
+def flash(message, category='message'):
+    """Flashes a message to the next request.  In order to remove the
+    flashed message from the session and to display it to the user,
+    the template has to call :func:`get_flashed_messages`.
+
+    .. versionchanged:: 0.3
+       `category` parameter added.
+
+    :param message: the message to be flashed.
+    :param category: the category for the message.  The following values
+                     are recommended: ``'message'`` for any kind of message,
+                     ``'error'`` for errors, ``'info'`` for information
+                     messages and ``'warning'`` for warnings.  However any
+                     kind of string can be used as category.
+    """
+    # Original implementation:
+    #
+    #     session.setdefault('_flashes', []).append((category, message))
+    #
+    # This assumed that changes made to mutable structures in the session are
+    # always in sync with the session object, which is not true for session
+    # implementations that use external storage for keeping their keys/values.
+    flashes = session.get('_flashes', [])
+    flashes.append((category, message))
+    session['_flashes'] = flashes
+    message_flashed.send(current_app._get_current_object(),
+                         message=message, category=category)
+
+
+def get_flashed_messages(with_categories=False, category_filter=[]):
+    """Pulls all flashed messages from the session and returns them.
+    Further calls in the same request to the function will return
+    the same messages.  By default just the messages are returned,
+    but when `with_categories` is set to ``True``, the return value will
+    be a list of tuples in the form ``(category, message)`` instead.
+
+    Filter the flashed messages to one or more categories by providing those
+    categories in `category_filter`.  This allows rendering categories in
+    separate html blocks.  The `with_categories` and `category_filter`
+    arguments are distinct:
+
+    * `with_categories` controls whether categories are returned with message
+      text (``True`` gives a tuple, where ``False`` gives just the message text).
+    * `category_filter` filters the messages down to only those matching the
+      provided categories.
+
+    See :ref:`message-flashing-pattern` for examples.
+
+    .. versionchanged:: 0.3
+       `with_categories` parameter added.
+
+    .. versionchanged:: 0.9
+        `category_filter` parameter added.
+
+    :param with_categories: set to ``True`` to also receive categories.
+    :param category_filter: whitelist of categories to limit return values
+    """
+    flashes = _request_ctx_stack.top.flashes
+    if flashes is None:
+        _request_ctx_stack.top.flashes = flashes = session.pop('_flashes') \
+            if '_flashes' in session else []
+    if category_filter:
+        flashes = list(filter(lambda f: f[0] in category_filter, flashes))
+    if not with_categories:
+        return [x[1] for x in flashes]
+    return flashes
+
+
+def send_file(filename_or_fp, mimetype=None, as_attachment=False,
+              attachment_filename=None, add_etags=True,
+              cache_timeout=None, conditional=False, last_modified=None):
+    """Sends the contents of a file to the client.  This will use the
+    most efficient method available and configured.  By default it will
+    try to use the WSGI server's file_wrapper support.  Alternatively
+    you can set the application's :attr:`~Flask.use_x_sendfile` attribute
+    to ``True`` to directly emit an ``X-Sendfile`` header.  This however
+    requires support of the underlying webserver for ``X-Sendfile``.
+
+    By default it will try to guess the mimetype for you, but you can
+    also explicitly provide one.  For extra security you probably want
+    to send certain files as attachment (HTML for instance).  The mimetype
+    guessing requires a `filename` or an `attachment_filename` to be
+    provided.
+
+    ETags will also be attached automatically if a `filename` is provided. You
+    can turn this off by setting `add_etags=False`.
+
+    If `conditional=True` and `filename` is provided, this method will try to
+    upgrade the response stream to support range requests.  This will allow
+    the request to be answered with partial content response.
+
+    Please never pass filenames to this function from user sources;
+    you should use :func:`send_from_directory` instead.
+
+    .. versionadded:: 0.2
+
+    .. versionadded:: 0.5
+       The `add_etags`, `cache_timeout` and `conditional` parameters were
+       added.  The default behavior is now to attach etags.
+
+    .. versionchanged:: 0.7
+       mimetype guessing and etag support for file objects was
+       deprecated because it was unreliable.  Pass a filename if you are
+       able to, otherwise attach an etag yourself.  This functionality
+       will be removed in Flask 1.0
+
+    .. versionchanged:: 0.9
+       cache_timeout pulls its default from application config, when None.
+
+    .. versionchanged:: 0.12
+       The filename is no longer automatically inferred from file objects. If
+       you want to use automatic mimetype and etag support, pass a filepath via
+       `filename_or_fp` or `attachment_filename`.
+
+    .. versionchanged:: 0.12
+       The `attachment_filename` is preferred over `filename` for MIME-type
+       detection.
+
+    .. versionchanged:: 1.0
+        UTF-8 filenames, as specified in `RFC 2231`_, are supported.
+
+    .. _RFC 2231: https://tools.ietf.org/html/rfc2231#section-4
+
+    .. versionchanged:: 1.0.3
+        Filenames are encoded with ASCII instead of Latin-1 for broader
+        compatibility with WSGI servers.
+
+    :param filename_or_fp: the filename of the file to send.
+                           This is relative to the :attr:`~Flask.root_path`
+                           if a relative path is specified.
+                           Alternatively a file object might be provided in
+                           which case ``X-Sendfile`` might not work and fall
+                           back to the traditional method.  Make sure that the
+                           file pointer is positioned at the start of data to
+                           send before calling :func:`send_file`.
+    :param mimetype: the mimetype of the file if provided. If a file path is
+                     given, auto detection happens as fallback, otherwise an
+                     error will be raised.
+    :param as_attachment: set to ``True`` if you want to send this file with
+                          a ``Content-Disposition: attachment`` header.
+    :param attachment_filename: the filename for the attachment if it
+                                differs from the file's filename.
+    :param add_etags: set to ``False`` to disable attaching of etags.
+    :param conditional: set to ``True`` to enable conditional responses.
+
+    :param cache_timeout: the timeout in seconds for the headers. When ``None``
+                          (default), this value is set by
+                          :meth:`~Flask.get_send_file_max_age` of
+                          :data:`~flask.current_app`.
+    :param last_modified: set the ``Last-Modified`` header to this value,
+        a :class:`~datetime.datetime` or timestamp.
+        If a file was passed, this overrides its mtime.
+    """
+    mtime = None
+    fsize = None
+    if isinstance(filename_or_fp, string_types):
+        filename = filename_or_fp
+        if not os.path.isabs(filename):
+            filename = os.path.join(current_app.root_path, filename)
+        file = None
+        if attachment_filename is None:
+            attachment_filename = os.path.basename(filename)
+    else:
+        file = filename_or_fp
+        filename = None
+
+    if mimetype is None:
+        if attachment_filename is not None:
+            mimetype = mimetypes.guess_type(attachment_filename)[0] \
+                or 'application/octet-stream'
+
+        if mimetype is None:
+            raise ValueError(
+                'Unable to infer MIME-type because no filename is available. '
+                'Please set either `attachment_filename`, pass a filepath to '
+                '`filename_or_fp` or set your own MIME-type via `mimetype`.'
+            )
+
+    headers = Headers()
+    if as_attachment:
+        if attachment_filename is None:
+            raise TypeError('filename unavailable, required for '
+                            'sending as attachment')
+
+        if not isinstance(attachment_filename, text_type):
+            attachment_filename = attachment_filename.decode('utf-8')
+
+        try:
+            attachment_filename = attachment_filename.encode('ascii')
+        except UnicodeEncodeError:
+            filenames = {
+                'filename': unicodedata.normalize(
+                    'NFKD', attachment_filename).encode('ascii', 'ignore'),
+                'filename*': "UTF-8''%s" % url_quote(attachment_filename),
+            }
+        else:
+            filenames = {'filename': attachment_filename}
+
+        headers.add('Content-Disposition', 'attachment', **filenames)
+
+    if current_app.use_x_sendfile and filename:
+        if file is not None:
+            file.close()
+        headers['X-Sendfile'] = filename
+        fsize = os.path.getsize(filename)
+        headers['Content-Length'] = fsize
+        data = None
+    else:
+        if file is None:
+            file = open(filename, 'rb')
+            mtime = os.path.getmtime(filename)
+            fsize = os.path.getsize(filename)
+            headers['Content-Length'] = fsize
+        data = wrap_file(request.environ, file)
+
+    rv = current_app.response_class(data, mimetype=mimetype, headers=headers,
+                                    direct_passthrough=True)
+
+    if last_modified is not None:
+        rv.last_modified = last_modified
+    elif mtime is not None:
+        rv.last_modified = mtime
+
+    rv.cache_control.public = True
+    if cache_timeout is None:
+        cache_timeout = current_app.get_send_file_max_age(filename)
+    if cache_timeout is not None:
+        rv.cache_control.max_age = cache_timeout
+        rv.expires = int(time() + cache_timeout)
+
+    if add_etags and filename is not None:
+        from warnings import warn
+
+        try:
+            rv.set_etag('%s-%s-%s' % (
+                os.path.getmtime(filename),
+                os.path.getsize(filename),
+                adler32(
+                    filename.encode('utf-8') if isinstance(filename, text_type)
+                    else filename
+                ) & 0xffffffff
+            ))
+        except OSError:
+            warn('Access %s failed, maybe it does not exist, so ignore etags in '
+                 'headers' % filename, stacklevel=2)
+
+    if conditional:
+        try:
+            rv = rv.make_conditional(request, accept_ranges=True,
+                                     complete_length=fsize)
+        except RequestedRangeNotSatisfiable:
+            if file is not None:
+                file.close()
+            raise
+        # make sure we don't send x-sendfile for servers that
+        # ignore the 304 status code for x-sendfile.
+        if rv.status_code == 304:
+            rv.headers.pop('x-sendfile', None)
+    return rv
+
+
+def safe_join(directory, *pathnames):
+    """Safely join `directory` and zero or more untrusted `pathnames`
+    components.
+
+    Example usage::
+
+        @app.route('/wiki/<path:filename>')
+        def wiki_page(filename):
+            filename = safe_join(app.config['WIKI_FOLDER'], filename)
+            with open(filename, 'rb') as fd:
+                content = fd.read()  # Read and process the file content...
+
+    :param directory: the trusted base directory.
+    :param pathnames: the untrusted pathnames relative to that directory.
+    :raises: :class:`~werkzeug.exceptions.NotFound` if one or more passed
+            paths fall out of its boundaries.
+    """
+
+    parts = [directory]
+
+    for filename in pathnames:
+        if filename != '':
+            filename = posixpath.normpath(filename)
+
+        if (
+            any(sep in filename for sep in _os_alt_seps)
+            or os.path.isabs(filename)
+            or filename == '..'
+            or filename.startswith('../')
+        ):
+            raise NotFound()
+
+        parts.append(filename)
+
+    return posixpath.join(*parts)
+
+
+def send_from_directory(directory, filename, **options):
+    """Send a file from a given directory with :func:`send_file`.  This
+    is a secure way to quickly expose static files from an upload folder
+    or something similar.
+
+    Example usage::
+
+        @app.route('/uploads/<path:filename>')
+        def download_file(filename):
+            return send_from_directory(app.config['UPLOAD_FOLDER'],
+                                       filename, as_attachment=True)
+
+    .. admonition:: Sending files and Performance
+
+       It is strongly recommended to activate either ``X-Sendfile`` support in
+       your webserver or (if no authentication happens) to tell the webserver
+       to serve files for the given path on its own without calling into the
+       web application for improved performance.
+
+    .. versionadded:: 0.5
+
+    :param directory: the directory where all the files are stored.
+    :param filename: the filename relative to that directory to
+                     download.
+    :param options: optional keyword arguments that are directly
+                    forwarded to :func:`send_file`.
+    """
+    filename = safe_join(directory, filename)
+    if not os.path.isabs(filename):
+        filename = os.path.join(current_app.root_path, filename)
+    try:
+        if not os.path.isfile(filename):
+            raise NotFound()
+    except (TypeError, ValueError):
+        raise BadRequest()
+    options.setdefault('conditional', True)
+    return send_file(filename, **options)
+
+
+def get_root_path(import_name):
+    """Returns the path to a package or cwd if that cannot be found.  This
+    returns the path of a package or the folder that contains a module.
+
+    Not to be confused with the package path returned by :func:`find_package`.
+    """
+    # Module already imported and has a file attribute.  Use that first.
+    mod = sys.modules.get(import_name)
+    if mod is not None and hasattr(mod, '__file__'):
+        return os.path.dirname(os.path.abspath(mod.__file__))
+
+    # Next attempt: check the loader.
+    loader = pkgutil.get_loader(import_name)
+
+    # Loader does not exist or we're referring to an unloaded main module
+    # or a main module without path (interactive sessions), go with the
+    # current working directory.
+    if loader is None or import_name == '__main__':
+        return os.getcwd()
+
+    # For .egg, zipimporter does not have get_filename until Python 2.7.
+    # Some other loaders might exhibit the same behavior.
+    if hasattr(loader, 'get_filename'):
+        filepath = loader.get_filename(import_name)
+    else:
+        # Fall back to imports.
+        __import__(import_name)
+        mod = sys.modules[import_name]
+        filepath = getattr(mod, '__file__', None)
+
+        # If we don't have a filepath it might be because we are a
+        # namespace package.  In this case we pick the root path from the
+        # first module that is contained in our package.
+        if filepath is None:
+            raise RuntimeError('No root path can be found for the provided '
+                               'module "%s".  This can happen because the '
+                               'module came from an import hook that does '
+                               'not provide file name information or because '
+                               'it\'s a namespace package.  In this case '
+                               'the root path needs to be explicitly '
+                               'provided.' % import_name)
+
+    # filepath is import_name.py for a module, or __init__.py for a package.
+    return os.path.dirname(os.path.abspath(filepath))
+
+
+def _matching_loader_thinks_module_is_package(loader, mod_name):
+    """Given the loader that loaded a module and the module this function
+    attempts to figure out if the given module is actually a package.
+    """
+    # If the loader can tell us if something is a package, we can
+    # directly ask the loader.
+    if hasattr(loader, 'is_package'):
+        return loader.is_package(mod_name)
+    # importlib's namespace loaders do not have this functionality but
+    # all the modules it loads are packages, so we can take advantage of
+    # this information.
+    elif (loader.__class__.__module__ == '_frozen_importlib' and
+          loader.__class__.__name__ == 'NamespaceLoader'):
+        return True
+    # Otherwise we need to fail with an error that explains what went
+    # wrong.
+    raise AttributeError(
+        ('%s.is_package() method is missing but is required by Flask of '
+         'PEP 302 import hooks.  If you do not use import hooks and '
+         'you encounter this error please file a bug against Flask.') %
+        loader.__class__.__name__)
+
+
+def find_package(import_name):
+    """Finds a package and returns the prefix (or None if the package is
+    not installed) as well as the folder that contains the package or
+    module as a tuple.  The package path returned is the module that would
+    have to be added to the pythonpath in order to make it possible to
+    import the module.  The prefix is the path below which a UNIX like
+    folder structure exists (lib, share etc.).
+    """
+    root_mod_name = import_name.split('.')[0]
+    loader = pkgutil.get_loader(root_mod_name)
+    if loader is None or import_name == '__main__':
+        # import name is not found, or interactive/main module
+        package_path = os.getcwd()
+    else:
+        # For .egg, zipimporter does not have get_filename until Python 2.7.
+        if hasattr(loader, 'get_filename'):
+            filename = loader.get_filename(root_mod_name)
+        elif hasattr(loader, 'archive'):
+            # zipimporter's loader.archive points to the .egg or .zip
+            # archive filename is dropped in call to dirname below.
+            filename = loader.archive
+        else:
+            # At least one loader is missing both get_filename and archive:
+            # Google App Engine's HardenedModulesHook
+            #
+            # Fall back to imports.
+            __import__(import_name)
+            filename = sys.modules[import_name].__file__
+        package_path = os.path.abspath(os.path.dirname(filename))
+
+        # In case the root module is a package we need to chop of the
+        # rightmost part.  This needs to go through a helper function
+        # because of python 3.3 namespace packages.
+        if _matching_loader_thinks_module_is_package(
+                loader, root_mod_name):
+            package_path = os.path.dirname(package_path)
+
+    site_parent, site_folder = os.path.split(package_path)
+    py_prefix = os.path.abspath(sys.prefix)
+    if package_path.startswith(py_prefix):
+        return py_prefix, package_path
+    elif site_folder.lower() == 'site-packages':
+        parent, folder = os.path.split(site_parent)
+        # Windows like installations
+        if folder.lower() == 'lib':
+            base_dir = parent
+        # UNIX like installations
+        elif os.path.basename(parent).lower() == 'lib':
+            base_dir = os.path.dirname(parent)
+        else:
+            base_dir = site_parent
+        return base_dir, package_path
+    return None, package_path
+
+
+class locked_cached_property(object):
+    """A decorator that converts a function into a lazy property.  The
+    function wrapped is called the first time to retrieve the result
+    and then that calculated result is used the next time you access
+    the value.  Works like the one in Werkzeug but has a lock for
+    thread safety.
+    """
+
+    def __init__(self, func, name=None, doc=None):
+        self.__name__ = name or func.__name__
+        self.__module__ = func.__module__
+        self.__doc__ = doc or func.__doc__
+        self.func = func
+        self.lock = RLock()
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+        with self.lock:
+            value = obj.__dict__.get(self.__name__, _missing)
+            if value is _missing:
+                value = self.func(obj)
+                obj.__dict__[self.__name__] = value
+            return value
+
+
+class _PackageBoundObject(object):
+    #: The name of the package or module that this app belongs to. Do not
+    #: change this once it is set by the constructor.
+    import_name = None
+
+    #: Location of the template files to be added to the template lookup.
+    #: ``None`` if templates should not be added.
+    template_folder = None
+
+    #: Absolute path to the package on the filesystem. Used to look up
+    #: resources contained in the package.
+    root_path = None
+
+    def __init__(self, import_name, template_folder=None, root_path=None):
+        self.import_name = import_name
+        self.template_folder = template_folder
+
+        if root_path is None:
+            root_path = get_root_path(self.import_name)
+
+        self.root_path = root_path
+        self._static_folder = None
+        self._static_url_path = None
+
+    def _get_static_folder(self):
+        if self._static_folder is not None:
+            return os.path.join(self.root_path, self._static_folder)
+
+    def _set_static_folder(self, value):
+        self._static_folder = value
+
+    static_folder = property(
+        _get_static_folder, _set_static_folder,
+        doc='The absolute path to the configured static folder.'
+    )
+    del _get_static_folder, _set_static_folder
+
+    def _get_static_url_path(self):
+        if self._static_url_path is not None:
+            return self._static_url_path
+
+        if self.static_folder is not None:
+            return '/' + os.path.basename(self.static_folder)
+
+    def _set_static_url_path(self, value):
+        self._static_url_path = value
+
+    static_url_path = property(
+        _get_static_url_path, _set_static_url_path,
+        doc='The URL prefix that the static route will be registered for.'
+    )
+    del _get_static_url_path, _set_static_url_path
+
+    @property
+    def has_static_folder(self):
+        """This is ``True`` if the package bound object's container has a
+        folder for static files.
+
+        .. versionadded:: 0.5
+        """
+        return self.static_folder is not None
+
+    @locked_cached_property
+    def jinja_loader(self):
+        """The Jinja loader for this package bound object.
+
+        .. versionadded:: 0.5
+        """
+        if self.template_folder is not None:
+            return FileSystemLoader(os.path.join(self.root_path,
+                                                 self.template_folder))
+
+    def get_send_file_max_age(self, filename):
+        """Provides default cache_timeout for the :func:`send_file` functions.
+
+        By default, this function returns ``SEND_FILE_MAX_AGE_DEFAULT`` from
+        the configuration of :data:`~flask.current_app`.
+
+        Static file functions such as :func:`send_from_directory` use this
+        function, and :func:`send_file` calls this function on
+        :data:`~flask.current_app` when the given cache_timeout is ``None``. If a
+        cache_timeout is given in :func:`send_file`, that timeout is used;
+        otherwise, this method is called.
+
+        This allows subclasses to change the behavior when sending files based
+        on the filename.  For example, to set the cache timeout for .js files
+        to 60 seconds::
+
+            class MyFlask(flask.Flask):
+                def get_send_file_max_age(self, name):
+                    if name.lower().endswith('.js'):
+                        return 60
+                    return flask.Flask.get_send_file_max_age(self, name)
+
+        .. versionadded:: 0.9
+        """
+        return total_seconds(current_app.send_file_max_age_default)
+
+    def send_static_file(self, filename):
+        """Function used internally to send static files from the static
+        folder to the browser.
+
+        .. versionadded:: 0.5
+        """
+        if not self.has_static_folder:
+            raise RuntimeError('No static folder for this object')
+        # Ensure get_send_file_max_age is called in all cases.
+        # Here, we ensure get_send_file_max_age is called for Blueprints.
+        cache_timeout = self.get_send_file_max_age(filename)
+        return send_from_directory(self.static_folder, filename,
+                                   cache_timeout=cache_timeout)
+
+    def open_resource(self, resource, mode='rb'):
+        """Opens a resource from the application's resource folder.  To see
+        how this works, consider the following folder structure::
+
+            /myapplication.py
+            /schema.sql
+            /static
+                /style.css
+            /templates
+                /layout.html
+                /index.html
+
+        If you want to open the :file:`schema.sql` file you would do the
+        following::
+
+            with app.open_resource('schema.sql') as f:
+                contents = f.read()
+                do_something_with(contents)
+
+        :param resource: the name of the resource.  To access resources within
+                         subfolders use forward slashes as separator.
+        :param mode: resource file opening mode, default is 'rb'.
+        """
+        if mode not in ('r', 'rb'):
+            raise ValueError('Resources can only be opened for reading')
+        return open(os.path.join(self.root_path, resource), mode)
+
+
+def total_seconds(td):
+    """Returns the total seconds from a timedelta object.
+
+    :param timedelta td: the timedelta to be converted in seconds
+
+    :returns: number of seconds
+    :rtype: int
+    """
+    return td.days * 60 * 60 * 24 + td.seconds
+
+
+def is_ip(value):
+    """Determine if the given string is an IP address.
+
+    Python 2 on Windows doesn't provide ``inet_pton``, so this only
+    checks IPv4 addresses in that environment.
+
+    :param value: value to check
+    :type value: str
+
+    :return: True if string is an IP address
+    :rtype: bool
+    """
+    if PY2 and os.name == 'nt':
+        try:
+            socket.inet_aton(value)
+            return True
+        except socket.error:
+            return False
+
+    for family in (socket.AF_INET, socket.AF_INET6):
+        try:
+            socket.inet_pton(family, value)
+        except socket.error:
+            pass
+        else:
+            return True
+
+    return False
diff --git a/python/flask/json/__init__.py b/python/flask/json/__init__.py
new file mode 100644
index 0000000..c24286c
--- /dev/null
+++ b/python/flask/json/__init__.py
@@ -0,0 +1,357 @@
+# -*- coding: utf-8 -*-
+"""
+flask.json
+~~~~~~~~~~
+
+:copyright: © 2010 by the Pallets team.
+:license: BSD, see LICENSE for more details.
+"""
+import codecs
+import io
+import uuid
+from datetime import date, datetime
+from flask.globals import current_app, request
+from flask._compat import text_type, PY2
+
+from werkzeug.http import http_date
+from jinja2 import Markup
+
+# Use the same json implementation as itsdangerous on which we
+# depend anyways.
+from itsdangerous import json as _json
+
+
+# Figure out if simplejson escapes slashes.  This behavior was changed
+# from one version to another without reason.
+_slash_escape = '\\/' not in _json.dumps('/')
+
+
+__all__ = ['dump', 'dumps', 'load', 'loads', 'htmlsafe_dump',
+           'htmlsafe_dumps', 'JSONDecoder', 'JSONEncoder',
+           'jsonify']
+
+
+def _wrap_reader_for_text(fp, encoding):
+    if isinstance(fp.read(0), bytes):
+        fp = io.TextIOWrapper(io.BufferedReader(fp), encoding)
+    return fp
+
+
+def _wrap_writer_for_text(fp, encoding):
+    try:
+        fp.write('')
+    except TypeError:
+        fp = io.TextIOWrapper(fp, encoding)
+    return fp
+
+
+class JSONEncoder(_json.JSONEncoder):
+    """The default Flask JSON encoder.  This one extends the default simplejson
+    encoder by also supporting ``datetime`` objects, ``UUID`` as well as
+    ``Markup`` objects which are serialized as RFC 822 datetime strings (same
+    as the HTTP date format).  In order to support more data types override the
+    :meth:`default` method.
+    """
+
+    def default(self, o):
+        """Implement this method in a subclass such that it returns a
+        serializable object for ``o``, or calls the base implementation (to
+        raise a :exc:`TypeError`).
+
+        For example, to support arbitrary iterators, you could implement
+        default like this::
+
+            def default(self, o):
+                try:
+                    iterable = iter(o)
+                except TypeError:
+                    pass
+                else:
+                    return list(iterable)
+                return JSONEncoder.default(self, o)
+        """
+        if isinstance(o, datetime):
+            return http_date(o.utctimetuple())
+        if isinstance(o, date):
+            return http_date(o.timetuple())
+        if isinstance(o, uuid.UUID):
+            return str(o)
+        if hasattr(o, '__html__'):
+            return text_type(o.__html__())
+        return _json.JSONEncoder.default(self, o)
+
+
+class JSONDecoder(_json.JSONDecoder):
+    """The default JSON decoder.  This one does not change the behavior from
+    the default simplejson decoder.  Consult the :mod:`json` documentation
+    for more information.  This decoder is not only used for the load
+    functions of this module but also :attr:`~flask.Request`.
+    """
+
+
+def _dump_arg_defaults(kwargs, app=None):
+    """Inject default arguments for dump functions."""
+    if app is None:
+        app = current_app
+
+    if app:
+        bp = app.blueprints.get(request.blueprint) if request else None
+        kwargs.setdefault(
+            'cls', bp.json_encoder if bp and bp.json_encoder else app.json_encoder
+        )
+
+        if not app.config['JSON_AS_ASCII']:
+            kwargs.setdefault('ensure_ascii', False)
+
+        kwargs.setdefault('sort_keys', app.config['JSON_SORT_KEYS'])
+    else:
+        kwargs.setdefault('sort_keys', True)
+        kwargs.setdefault('cls', JSONEncoder)
+
+
+def _load_arg_defaults(kwargs, app=None):
+    """Inject default arguments for load functions."""
+    if app is None:
+        app = current_app
+
+    if app:
+        bp = app.blueprints.get(request.blueprint) if request else None
+        kwargs.setdefault(
+            'cls',
+            bp.json_decoder if bp and bp.json_decoder
+                else app.json_decoder
+        )
+    else:
+        kwargs.setdefault('cls', JSONDecoder)
+
+
+def detect_encoding(data):
+    """Detect which UTF codec was used to encode the given bytes.
+
+    The latest JSON standard (:rfc:`8259`) suggests that only UTF-8 is
+    accepted. Older documents allowed 8, 16, or 32. 16 and 32 can be big
+    or little endian. Some editors or libraries may prepend a BOM.
+
+    :param data: Bytes in unknown UTF encoding.
+    :return: UTF encoding name
+    """
+    head = data[:4]
+
+    if head[:3] == codecs.BOM_UTF8:
+        return 'utf-8-sig'
+
+    if b'\x00' not in head:
+        return 'utf-8'
+
+    if head in (codecs.BOM_UTF32_BE, codecs.BOM_UTF32_LE):
+        return 'utf-32'
+
+    if head[:2] in (codecs.BOM_UTF16_BE, codecs.BOM_UTF16_LE):
+        return 'utf-16'
+
+    if len(head) == 4:
+        if head[:3] == b'\x00\x00\x00':
+            return 'utf-32-be'
+
+        if head[::2] == b'\x00\x00':
+            return 'utf-16-be'
+
+        if head[1:] == b'\x00\x00\x00':
+            return 'utf-32-le'
+
+        if head[1::2] == b'\x00\x00':
+            return 'utf-16-le'
+
+    if len(head) == 2:
+        return 'utf-16-be' if head.startswith(b'\x00') else 'utf-16-le'
+
+    return 'utf-8'
+
+
+def dumps(obj, app=None, **kwargs):
+    """Serialize ``obj`` to a JSON-formatted string. If there is an
+    app context pushed, use the current app's configured encoder
+    (:attr:`~flask.Flask.json_encoder`), or fall back to the default
+    :class:`JSONEncoder`.
+
+    Takes the same arguments as the built-in :func:`json.dumps`, and
+    does some extra configuration based on the application. If the
+    simplejson package is installed, it is preferred.
+
+    :param obj: Object to serialize to JSON.
+    :param app: App instance to use to configure the JSON encoder.
+        Uses ``current_app`` if not given, and falls back to the default
+        encoder when not in an app context.
+    :param kwargs: Extra arguments passed to :func:`json.dumps`.
+
+    .. versionchanged:: 1.0.3
+
+        ``app`` can be passed directly, rather than requiring an app
+        context for configuration.
+    """
+    _dump_arg_defaults(kwargs, app=app)
+    encoding = kwargs.pop('encoding', None)
+    rv = _json.dumps(obj, **kwargs)
+    if encoding is not None and isinstance(rv, text_type):
+        rv = rv.encode(encoding)
+    return rv
+
+
+def dump(obj, fp, app=None, **kwargs):
+    """Like :func:`dumps` but writes into a file object."""
+    _dump_arg_defaults(kwargs, app=app)
+    encoding = kwargs.pop('encoding', None)
+    if encoding is not None:
+        fp = _wrap_writer_for_text(fp, encoding)
+    _json.dump(obj, fp, **kwargs)
+
+
+def loads(s, app=None, **kwargs):
+    """Deserialize an object from a JSON-formatted string ``s``. If
+    there is an app context pushed, use the current app's configured
+    decoder (:attr:`~flask.Flask.json_decoder`), or fall back to the
+    default :class:`JSONDecoder`.
+
+    Takes the same arguments as the built-in :func:`json.loads`, and
+    does some extra configuration based on the application. If the
+    simplejson package is installed, it is preferred.
+
+    :param s: JSON string to deserialize.
+    :param app: App instance to use to configure the JSON decoder.
+        Uses ``current_app`` if not given, and falls back to the default
+        encoder when not in an app context.
+    :param kwargs: Extra arguments passed to :func:`json.dumps`.
+
+    .. versionchanged:: 1.0.3
+
+        ``app`` can be passed directly, rather than requiring an app
+        context for configuration.
+    """
+    _load_arg_defaults(kwargs, app=app)
+    if isinstance(s, bytes):
+        encoding = kwargs.pop('encoding', None)
+        if encoding is None:
+            encoding = detect_encoding(s)
+        s = s.decode(encoding)
+    return _json.loads(s, **kwargs)
+
+
+def load(fp, app=None, **kwargs):
+    """Like :func:`loads` but reads from a file object."""
+    _load_arg_defaults(kwargs, app=app)
+    if not PY2:
+        fp = _wrap_reader_for_text(fp, kwargs.pop('encoding', None) or 'utf-8')
+    return _json.load(fp, **kwargs)
+
+
+def htmlsafe_dumps(obj, **kwargs):
+    """Works exactly like :func:`dumps` but is safe for use in ``<script>``
+    tags.  It accepts the same arguments and returns a JSON string.  Note that
+    this is available in templates through the ``|tojson`` filter which will
+    also mark the result as safe.  Due to how this function escapes certain
+    characters this is safe even if used outside of ``<script>`` tags.
+
+    The following characters are escaped in strings:
+
+    -   ``<``
+    -   ``>``
+    -   ``&``
+    -   ``'``
+
+    This makes it safe to embed such strings in any place in HTML with the
+    notable exception of double quoted attributes.  In that case single
+    quote your attributes or HTML escape it in addition.
+
+    .. versionchanged:: 0.10
+       This function's return value is now always safe for HTML usage, even
+       if outside of script tags or if used in XHTML.  This rule does not
+       hold true when using this function in HTML attributes that are double
+       quoted.  Always single quote attributes if you use the ``|tojson``
+       filter.  Alternatively use ``|tojson|forceescape``.
+    """
+    rv = dumps(obj, **kwargs) \
+        .replace(u'<', u'\\u003c') \
+        .replace(u'>', u'\\u003e') \
+        .replace(u'&', u'\\u0026') \
+        .replace(u"'", u'\\u0027')
+    if not _slash_escape:
+        rv = rv.replace('\\/', '/')
+    return rv
+
+
+def htmlsafe_dump(obj, fp, **kwargs):
+    """Like :func:`htmlsafe_dumps` but writes into a file object."""
+    fp.write(text_type(htmlsafe_dumps(obj, **kwargs)))
+
+
+def jsonify(*args, **kwargs):
+    """This function wraps :func:`dumps` to add a few enhancements that make
+    life easier.  It turns the JSON output into a :class:`~flask.Response`
+    object with the :mimetype:`application/json` mimetype.  For convenience, it
+    also converts multiple arguments into an array or multiple keyword arguments
+    into a dict.  This means that both ``jsonify(1,2,3)`` and
+    ``jsonify([1,2,3])`` serialize to ``[1,2,3]``.
+
+    For clarity, the JSON serialization behavior has the following differences
+    from :func:`dumps`:
+
+    1. Single argument: Passed straight through to :func:`dumps`.
+    2. Multiple arguments: Converted to an array before being passed to
+       :func:`dumps`.
+    3. Multiple keyword arguments: Converted to a dict before being passed to
+       :func:`dumps`.
+    4. Both args and kwargs: Behavior undefined and will throw an exception.
+
+    Example usage::
+
+        from flask import jsonify
+
+        @app.route('/_get_current_user')
+        def get_current_user():
+            return jsonify(username=g.user.username,
+                           email=g.user.email,
+                           id=g.user.id)
+
+    This will send a JSON response like this to the browser::
+
+        {
+            "username": "admin",
+            "email": "admin@localhost",
+            "id": 42
+        }
+
+
+    .. versionchanged:: 0.11
+       Added support for serializing top-level arrays. This introduces a
+       security risk in ancient browsers. See :ref:`json-security` for details.
+
+    This function's response will be pretty printed if the
+    ``JSONIFY_PRETTYPRINT_REGULAR`` config parameter is set to True or the
+    Flask app is running in debug mode. Compressed (not pretty) formatting
+    currently means no indents and no spaces after separators.
+
+    .. versionadded:: 0.2
+    """
+
+    indent = None
+    separators = (',', ':')
+
+    if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] or current_app.debug:
+        indent = 2
+        separators = (', ', ': ')
+
+    if args and kwargs:
+        raise TypeError('jsonify() behavior undefined when passed both args and kwargs')
+    elif len(args) == 1:  # single args are passed directly to dumps()
+        data = args[0]
+    else:
+        data = args or kwargs
+
+    return current_app.response_class(
+        dumps(data, indent=indent, separators=separators) + '\n',
+        mimetype=current_app.config['JSONIFY_MIMETYPE']
+    )
+
+
+def tojson_filter(obj, **kwargs):
+    return Markup(htmlsafe_dumps(obj, **kwargs))
diff --git a/python/flask/json/tag.py b/python/flask/json/tag.py
new file mode 100644
index 0000000..11c966c
--- /dev/null
+++ b/python/flask/json/tag.py
@@ -0,0 +1,300 @@
+# -*- coding: utf-8 -*-
+"""
+Tagged JSON
+~~~~~~~~~~~
+
+A compact representation for lossless serialization of non-standard JSON types.
+:class:`~flask.sessions.SecureCookieSessionInterface` uses this to serialize
+the session data, but it may be useful in other places. It can be extended to
+support other types.
+
+.. autoclass:: TaggedJSONSerializer
+    :members:
+
+.. autoclass:: JSONTag
+    :members:
+
+Let's seen an example that adds support for :class:`~collections.OrderedDict`.
+Dicts don't have an order in Python or JSON, so to handle this we will dump
+the items as a list of ``[key, value]`` pairs. Subclass :class:`JSONTag` and
+give it the new key ``' od'`` to identify the type. The session serializer
+processes dicts first, so insert the new tag at the front of the order since
+``OrderedDict`` must be processed before ``dict``. ::
+
+    from flask.json.tag import JSONTag
+
+    class TagOrderedDict(JSONTag):
+        __slots__ = ('serializer',)
+        key = ' od'
+
+        def check(self, value):
+            return isinstance(value, OrderedDict)
+
+        def to_json(self, value):
+            return [[k, self.serializer.tag(v)] for k, v in iteritems(value)]
+
+        def to_python(self, value):
+            return OrderedDict(value)
+
+    app.session_interface.serializer.register(TagOrderedDict, index=0)
+
+:copyright: © 2010 by the Pallets team.
+:license: BSD, see LICENSE for more details.
+"""
+
+from base64 import b64decode, b64encode
+from datetime import datetime
+from uuid import UUID
+
+from jinja2 import Markup
+from werkzeug.http import http_date, parse_date
+
+from flask._compat import iteritems, text_type
+from flask.json import dumps, loads
+
+
+class JSONTag(object):
+    """Base class for defining type tags for :class:`TaggedJSONSerializer`."""
+
+    __slots__ = ('serializer',)
+
+    #: The tag to mark the serialized object with. If ``None``, this tag is
+    #: only used as an intermediate step during tagging.
+    key = None
+
+    def __init__(self, serializer):
+        """Create a tagger for the given serializer."""
+        self.serializer = serializer
+
+    def check(self, value):
+        """Check if the given value should be tagged by this tag."""
+        raise NotImplementedError
+
+    def to_json(self, value):
+        """Convert the Python object to an object that is a valid JSON type.
+        The tag will be added later."""
+        raise NotImplementedError
+
+    def to_python(self, value):
+        """Convert the JSON representation back to the correct type. The tag
+        will already be removed."""
+        raise NotImplementedError
+
+    def tag(self, value):
+        """Convert the value to a valid JSON type and add the tag structure
+        around it."""
+        return {self.key: self.to_json(value)}
+
+
+class TagDict(JSONTag):
+    """Tag for 1-item dicts whose only key matches a registered tag.
+
+    Internally, the dict key is suffixed with `__`, and the suffix is removed
+    when deserializing.
+    """
+
+    __slots__ = ()
+    key = ' di'
+
+    def check(self, value):
+        return (
+            isinstance(value, dict)
+            and len(value) == 1
+            and next(iter(value)) in self.serializer.tags
+        )
+
+    def to_json(self, value):
+        key = next(iter(value))
+        return {key + '__': self.serializer.tag(value[key])}
+
+    def to_python(self, value):
+        key = next(iter(value))
+        return {key[:-2]: value[key]}
+
+
+class PassDict(JSONTag):
+    __slots__ = ()
+
+    def check(self, value):
+        return isinstance(value, dict)
+
+    def to_json(self, value):
+        # JSON objects may only have string keys, so don't bother tagging the
+        # key here.
+        return dict((k, self.serializer.tag(v)) for k, v in iteritems(value))
+
+    tag = to_json
+
+
+class TagTuple(JSONTag):
+    __slots__ = ()
+    key = ' t'
+
+    def check(self, value):
+        return isinstance(value, tuple)
+
+    def to_json(self, value):
+        return [self.serializer.tag(item) for item in value]
+
+    def to_python(self, value):
+        return tuple(value)
+
+
+class PassList(JSONTag):
+    __slots__ = ()
+
+    def check(self, value):
+        return isinstance(value, list)
+
+    def to_json(self, value):
+        return [self.serializer.tag(item) for item in value]
+
+    tag = to_json
+
+
+class TagBytes(JSONTag):
+    __slots__ = ()
+    key = ' b'
+
+    def check(self, value):
+        return isinstance(value, bytes)
+
+    def to_json(self, value):
+        return b64encode(value).decode('ascii')
+
+    def to_python(self, value):
+        return b64decode(value)
+
+
+class TagMarkup(JSONTag):
+    """Serialize anything matching the :class:`~flask.Markup` API by
+    having a ``__html__`` method to the result of that method. Always
+    deserializes to an instance of :class:`~flask.Markup`."""
+
+    __slots__ = ()
+    key = ' m'
+
+    def check(self, value):
+        return callable(getattr(value, '__html__', None))
+
+    def to_json(self, value):
+        return text_type(value.__html__())
+
+    def to_python(self, value):
+        return Markup(value)
+
+
+class TagUUID(JSONTag):
+    __slots__ = ()
+    key = ' u'
+
+    def check(self, value):
+        return isinstance(value, UUID)
+
+    def to_json(self, value):
+        return value.hex
+
+    def to_python(self, value):
+        return UUID(value)
+
+
+class TagDateTime(JSONTag):
+    __slots__ = ()
+    key = ' d'
+
+    def check(self, value):
+        return isinstance(value, datetime)
+
+    def to_json(self, value):
+        return http_date(value)
+
+    def to_python(self, value):
+        return parse_date(value)
+
+
+class TaggedJSONSerializer(object):
+    """Serializer that uses a tag system to compactly represent objects that
+    are not JSON types. Passed as the intermediate serializer to
+    :class:`itsdangerous.Serializer`.
+
+    The following extra types are supported:
+
+    * :class:`dict`
+    * :class:`tuple`
+    * :class:`bytes`
+    * :class:`~flask.Markup`
+    * :class:`~uuid.UUID`
+    * :class:`~datetime.datetime`
+    """
+
+    __slots__ = ('tags', 'order')
+
+    #: Tag classes to bind when creating the serializer. Other tags can be
+    #: added later using :meth:`~register`.
+    default_tags = [
+        TagDict, PassDict, TagTuple, PassList, TagBytes, TagMarkup, TagUUID,
+        TagDateTime,
+    ]
+
+    def __init__(self):
+        self.tags = {}
+        self.order = []
+
+        for cls in self.default_tags:
+            self.register(cls)
+
+    def register(self, tag_class, force=False, index=None):
+        """Register a new tag with this serializer.
+
+        :param tag_class: tag class to register. Will be instantiated with this
+            serializer instance.
+        :param force: overwrite an existing tag. If false (default), a
+            :exc:`KeyError` is raised.
+        :param index: index to insert the new tag in the tag order. Useful when
+            the new tag is a special case of an existing tag. If ``None``
+            (default), the tag is appended to the end of the order.
+
+        :raise KeyError: if the tag key is already registered and ``force`` is
+            not true.
+        """
+        tag = tag_class(self)
+        key = tag.key
+
+        if key is not None:
+            if not force and key in self.tags:
+                raise KeyError("Tag '{0}' is already registered.".format(key))
+
+            self.tags[key] = tag
+
+        if index is None:
+            self.order.append(tag)
+        else:
+            self.order.insert(index, tag)
+
+    def tag(self, value):
+        """Convert a value to a tagged representation if necessary."""
+        for tag in self.order:
+            if tag.check(value):
+                return tag.tag(value)
+
+        return value
+
+    def untag(self, value):
+        """Convert a tagged representation back to the original type."""
+        if len(value) != 1:
+            return value
+
+        key = next(iter(value))
+
+        if key not in self.tags:
+            return value
+
+        return self.tags[key].to_python(value[key])
+
+    def dumps(self, value):
+        """Tag the value and dump it to a compact JSON string."""
+        return dumps(self.tag(value), separators=(',', ':'))
+
+    def loads(self, value):
+        """Load data from a JSON string and deserialized any tagged objects."""
+        return loads(value, object_hook=self.untag)
diff --git a/python/flask/logging.py b/python/flask/logging.py
new file mode 100644
index 0000000..389c2c2
--- /dev/null
+++ b/python/flask/logging.py
@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+"""
+flask.logging
+~~~~~~~~~~~~~
+
+:copyright: © 2010 by the Pallets team.
+:license: BSD, see LICENSE for more details.
+"""
+
+from __future__ import absolute_import
+
+import logging
+import sys
+
+from werkzeug.local import LocalProxy
+
+from .globals import request
+
+
+@LocalProxy
+def wsgi_errors_stream():
+    """Find the most appropriate error stream for the application. If a request
+    is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``.
+
+    If you configure your own :class:`logging.StreamHandler`, you may want to
+    use this for the stream. If you are using file or dict configuration and
+    can't import this directly, you can refer to it as
+    ``ext://flask.logging.wsgi_errors_stream``.
+    """
+    return request.environ['wsgi.errors'] if request else sys.stderr
+
+
+def has_level_handler(logger):
+    """Check if there is a handler in the logging chain that will handle the
+    given logger's :meth:`effective level <~logging.Logger.getEffectiveLevel>`.
+    """
+    level = logger.getEffectiveLevel()
+    current = logger
+
+    while current:
+        if any(handler.level <= level for handler in current.handlers):
+            return True
+
+        if not current.propagate:
+            break
+
+        current = current.parent
+
+    return False
+
+
+#: Log messages to :func:`~flask.logging.wsgi_errors_stream` with the format
+#: ``[%(asctime)s] %(levelname)s in %(module)s: %(message)s``.
+default_handler = logging.StreamHandler(wsgi_errors_stream)
+default_handler.setFormatter(logging.Formatter(
+    '[%(asctime)s] %(levelname)s in %(module)s: %(message)s'
+))
+
+
+def create_logger(app):
+    """Get the ``'flask.app'`` logger and configure it if needed.
+
+    When :attr:`~flask.Flask.debug` is enabled, set the logger level to
+    :data:`logging.DEBUG` if it is not set.
+
+    If there is no handler for the logger's effective level, add a
+    :class:`~logging.StreamHandler` for
+    :func:`~flask.logging.wsgi_errors_stream` with a basic format.
+    """
+    logger = logging.getLogger('flask.app')
+
+    if app.debug and logger.level == logging.NOTSET:
+        logger.setLevel(logging.DEBUG)
+
+    if not has_level_handler(logger):
+        logger.addHandler(default_handler)
+
+    return logger
diff --git a/python/flask/sessions.py b/python/flask/sessions.py
new file mode 100644
index 0000000..c8b7d4e
--- /dev/null
+++ b/python/flask/sessions.py
@@ -0,0 +1,385 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.sessions
+    ~~~~~~~~~~~~~~
+
+    Implements cookie based sessions based on itsdangerous.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import hashlib
+import warnings
+from datetime import datetime
+
+from itsdangerous import BadSignature, URLSafeTimedSerializer
+from werkzeug.datastructures import CallbackDict
+
+from flask._compat import collections_abc
+from flask.helpers import is_ip, total_seconds
+from flask.json.tag import TaggedJSONSerializer
+
+
+class SessionMixin(collections_abc.MutableMapping):
+    """Expands a basic dictionary with session attributes."""
+
+    @property
+    def permanent(self):
+        """This reflects the ``'_permanent'`` key in the dict."""
+        return self.get('_permanent', False)
+
+    @permanent.setter
+    def permanent(self, value):
+        self['_permanent'] = bool(value)
+
+    #: Some implementations can detect whether a session is newly
+    #: created, but that is not guaranteed. Use with caution. The mixin
+    # default is hard-coded ``False``.
+    new = False
+
+    #: Some implementations can detect changes to the session and set
+    #: this when that happens. The mixin default is hard coded to
+    #: ``True``.
+    modified = True
+
+    #: Some implementations can detect when session data is read or
+    #: written and set this when that happens. The mixin default is hard
+    #: coded to ``True``.
+    accessed = True
+
+
+class SecureCookieSession(CallbackDict, SessionMixin):
+    """Base class for sessions based on signed cookies.
+
+    This session backend will set the :attr:`modified` and
+    :attr:`accessed` attributes. It cannot reliably track whether a
+    session is new (vs. empty), so :attr:`new` remains hard coded to
+    ``False``.
+    """
+
+    #: When data is changed, this is set to ``True``. Only the session
+    #: dictionary itself is tracked; if the session contains mutable
+    #: data (for example a nested dict) then this must be set to
+    #: ``True`` manually when modifying that data. The session cookie
+    #: will only be written to the response if this is ``True``.
+    modified = False
+
+    #: When data is read or written, this is set to ``True``. Used by
+    # :class:`.SecureCookieSessionInterface` to add a ``Vary: Cookie``
+    #: header, which allows caching proxies to cache different pages for
+    #: different users.
+    accessed = False
+
+    def __init__(self, initial=None):
+        def on_update(self):
+            self.modified = True
+            self.accessed = True
+
+        super(SecureCookieSession, self).__init__(initial, on_update)
+
+    def __getitem__(self, key):
+        self.accessed = True
+        return super(SecureCookieSession, self).__getitem__(key)
+
+    def get(self, key, default=None):
+        self.accessed = True
+        return super(SecureCookieSession, self).get(key, default)
+
+    def setdefault(self, key, default=None):
+        self.accessed = True
+        return super(SecureCookieSession, self).setdefault(key, default)
+
+
+class NullSession(SecureCookieSession):
+    """Class used to generate nicer error messages if sessions are not
+    available.  Will still allow read-only access to the empty session
+    but fail on setting.
+    """
+
+    def _fail(self, *args, **kwargs):
+        raise RuntimeError('The session is unavailable because no secret '
+                           'key was set.  Set the secret_key on the '
+                           'application to something unique and secret.')
+    __setitem__ = __delitem__ = clear = pop = popitem = \
+        update = setdefault = _fail
+    del _fail
+
+
+class SessionInterface(object):
+    """The basic interface you have to implement in order to replace the
+    default session interface which uses werkzeug's securecookie
+    implementation.  The only methods you have to implement are
+    :meth:`open_session` and :meth:`save_session`, the others have
+    useful defaults which you don't need to change.
+
+    The session object returned by the :meth:`open_session` method has to
+    provide a dictionary like interface plus the properties and methods
+    from the :class:`SessionMixin`.  We recommend just subclassing a dict
+    and adding that mixin::
+
+        class Session(dict, SessionMixin):
+            pass
+
+    If :meth:`open_session` returns ``None`` Flask will call into
+    :meth:`make_null_session` to create a session that acts as replacement
+    if the session support cannot work because some requirement is not
+    fulfilled.  The default :class:`NullSession` class that is created
+    will complain that the secret key was not set.
+
+    To replace the session interface on an application all you have to do
+    is to assign :attr:`flask.Flask.session_interface`::
+
+        app = Flask(__name__)
+        app.session_interface = MySessionInterface()
+
+    .. versionadded:: 0.8
+    """
+
+    #: :meth:`make_null_session` will look here for the class that should
+    #: be created when a null session is requested.  Likewise the
+    #: :meth:`is_null_session` method will perform a typecheck against
+    #: this type.
+    null_session_class = NullSession
+
+    #: A flag that indicates if the session interface is pickle based.
+    #: This can be used by Flask extensions to make a decision in regards
+    #: to how to deal with the session object.
+    #:
+    #: .. versionadded:: 0.10
+    pickle_based = False
+
+    def make_null_session(self, app):
+        """Creates a null session which acts as a replacement object if the
+        real session support could not be loaded due to a configuration
+        error.  This mainly aids the user experience because the job of the
+        null session is to still support lookup without complaining but
+        modifications are answered with a helpful error message of what
+        failed.
+
+        This creates an instance of :attr:`null_session_class` by default.
+        """
+        return self.null_session_class()
+
+    def is_null_session(self, obj):
+        """Checks if a given object is a null session.  Null sessions are
+        not asked to be saved.
+
+        This checks if the object is an instance of :attr:`null_session_class`
+        by default.
+        """
+        return isinstance(obj, self.null_session_class)
+
+    def get_cookie_domain(self, app):
+        """Returns the domain that should be set for the session cookie.
+
+        Uses ``SESSION_COOKIE_DOMAIN`` if it is configured, otherwise
+        falls back to detecting the domain based on ``SERVER_NAME``.
+
+        Once detected (or if not set at all), ``SESSION_COOKIE_DOMAIN`` is
+        updated to avoid re-running the logic.
+        """
+
+        rv = app.config['SESSION_COOKIE_DOMAIN']
+
+        # set explicitly, or cached from SERVER_NAME detection
+        # if False, return None
+        if rv is not None:
+            return rv if rv else None
+
+        rv = app.config['SERVER_NAME']
+
+        # server name not set, cache False to return none next time
+        if not rv:
+            app.config['SESSION_COOKIE_DOMAIN'] = False
+            return None
+
+        # chop off the port which is usually not supported by browsers
+        # remove any leading '.' since we'll add that later
+        rv = rv.rsplit(':', 1)[0].lstrip('.')
+
+        if '.' not in rv:
+            # Chrome doesn't allow names without a '.'
+            # this should only come up with localhost
+            # hack around this by not setting the name, and show a warning
+            warnings.warn(
+                '"{rv}" is not a valid cookie domain, it must contain a ".".'
+                ' Add an entry to your hosts file, for example'
+                ' "{rv}.localdomain", and use that instead.'.format(rv=rv)
+            )
+            app.config['SESSION_COOKIE_DOMAIN'] = False
+            return None
+
+        ip = is_ip(rv)
+
+        if ip:
+            warnings.warn(
+                'The session cookie domain is an IP address. This may not work'
+                ' as intended in some browsers. Add an entry to your hosts'
+                ' file, for example "localhost.localdomain", and use that'
+                ' instead.'
+            )
+
+        # if this is not an ip and app is mounted at the root, allow subdomain
+        # matching by adding a '.' prefix
+        if self.get_cookie_path(app) == '/' and not ip:
+            rv = '.' + rv
+
+        app.config['SESSION_COOKIE_DOMAIN'] = rv
+        return rv
+
+    def get_cookie_path(self, app):
+        """Returns the path for which the cookie should be valid.  The
+        default implementation uses the value from the ``SESSION_COOKIE_PATH``
+        config var if it's set, and falls back to ``APPLICATION_ROOT`` or
+        uses ``/`` if it's ``None``.
+        """
+        return app.config['SESSION_COOKIE_PATH'] \
+               or app.config['APPLICATION_ROOT']
+
+    def get_cookie_httponly(self, app):
+        """Returns True if the session cookie should be httponly.  This
+        currently just returns the value of the ``SESSION_COOKIE_HTTPONLY``
+        config var.
+        """
+        return app.config['SESSION_COOKIE_HTTPONLY']
+
+    def get_cookie_secure(self, app):
+        """Returns True if the cookie should be secure.  This currently
+        just returns the value of the ``SESSION_COOKIE_SECURE`` setting.
+        """
+        return app.config['SESSION_COOKIE_SECURE']
+
+    def get_cookie_samesite(self, app):
+        """Return ``'Strict'`` or ``'Lax'`` if the cookie should use the
+        ``SameSite`` attribute. This currently just returns the value of
+        the :data:`SESSION_COOKIE_SAMESITE` setting.
+        """
+        return app.config['SESSION_COOKIE_SAMESITE']
+
+    def get_expiration_time(self, app, session):
+        """A helper method that returns an expiration date for the session
+        or ``None`` if the session is linked to the browser session.  The
+        default implementation returns now + the permanent session
+        lifetime configured on the application.
+        """
+        if session.permanent:
+            return datetime.utcnow() + app.permanent_session_lifetime
+
+    def should_set_cookie(self, app, session):
+        """Used by session backends to determine if a ``Set-Cookie`` header
+        should be set for this session cookie for this response. If the session
+        has been modified, the cookie is set. If the session is permanent and
+        the ``SESSION_REFRESH_EACH_REQUEST`` config is true, the cookie is
+        always set.
+
+        This check is usually skipped if the session was deleted.
+
+        .. versionadded:: 0.11
+        """
+
+        return session.modified or (
+            session.permanent and app.config['SESSION_REFRESH_EACH_REQUEST']
+        )
+
+    def open_session(self, app, request):
+        """This method has to be implemented and must either return ``None``
+        in case the loading failed because of a configuration error or an
+        instance of a session object which implements a dictionary like
+        interface + the methods and attributes on :class:`SessionMixin`.
+        """
+        raise NotImplementedError()
+
+    def save_session(self, app, session, response):
+        """This is called for actual sessions returned by :meth:`open_session`
+        at the end of the request.  This is still called during a request
+        context so if you absolutely need access to the request you can do
+        that.
+        """
+        raise NotImplementedError()
+
+
+session_json_serializer = TaggedJSONSerializer()
+
+
+class SecureCookieSessionInterface(SessionInterface):
+    """The default session interface that stores sessions in signed cookies
+    through the :mod:`itsdangerous` module.
+    """
+    #: the salt that should be applied on top of the secret key for the
+    #: signing of cookie based sessions.
+    salt = 'cookie-session'
+    #: the hash function to use for the signature.  The default is sha1
+    digest_method = staticmethod(hashlib.sha1)
+    #: the name of the itsdangerous supported key derivation.  The default
+    #: is hmac.
+    key_derivation = 'hmac'
+    #: A python serializer for the payload.  The default is a compact
+    #: JSON derived serializer with support for some extra Python types
+    #: such as datetime objects or tuples.
+    serializer = session_json_serializer
+    session_class = SecureCookieSession
+
+    def get_signing_serializer(self, app):
+        if not app.secret_key:
+            return None
+        signer_kwargs = dict(
+            key_derivation=self.key_derivation,
+            digest_method=self.digest_method
+        )
+        return URLSafeTimedSerializer(app.secret_key, salt=self.salt,
+                                      serializer=self.serializer,
+                                      signer_kwargs=signer_kwargs)
+
+    def open_session(self, app, request):
+        s = self.get_signing_serializer(app)
+        if s is None:
+            return None
+        val = request.cookies.get(app.session_cookie_name)
+        if not val:
+            return self.session_class()
+        max_age = total_seconds(app.permanent_session_lifetime)
+        try:
+            data = s.loads(val, max_age=max_age)
+            return self.session_class(data)
+        except BadSignature:
+            return self.session_class()
+
+    def save_session(self, app, session, response):
+        domain = self.get_cookie_domain(app)
+        path = self.get_cookie_path(app)
+
+        # If the session is modified to be empty, remove the cookie.
+        # If the session is empty, return without setting the cookie.
+        if not session:
+            if session.modified:
+                response.delete_cookie(
+                    app.session_cookie_name,
+                    domain=domain,
+                    path=path
+                )
+
+            return
+
+        # Add a "Vary: Cookie" header if the session was accessed at all.
+        if session.accessed:
+            response.vary.add('Cookie')
+
+        if not self.should_set_cookie(app, session):
+            return
+
+        httponly = self.get_cookie_httponly(app)
+        secure = self.get_cookie_secure(app)
+        samesite = self.get_cookie_samesite(app)
+        expires = self.get_expiration_time(app, session)
+        val = self.get_signing_serializer(app).dumps(dict(session))
+        response.set_cookie(
+            app.session_cookie_name,
+            val,
+            expires=expires,
+            httponly=httponly,
+            domain=domain,
+            path=path,
+            secure=secure,
+            samesite=samesite
+        )
diff --git a/python/flask/signals.py b/python/flask/signals.py
new file mode 100644
index 0000000..18f2630
--- /dev/null
+++ b/python/flask/signals.py
@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.signals
+    ~~~~~~~~~~~~~
+
+    Implements signals based on blinker if available, otherwise
+    falls silently back to a noop.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+signals_available = False
+try:
+    from blinker import Namespace
+    signals_available = True
+except ImportError:
+    class Namespace(object):
+        def signal(self, name, doc=None):
+            return _FakeSignal(name, doc)
+
+    class _FakeSignal(object):
+        """If blinker is unavailable, create a fake class with the same
+        interface that allows sending of signals but will fail with an
+        error on anything else.  Instead of doing anything on send, it
+        will just ignore the arguments and do nothing instead.
+        """
+
+        def __init__(self, name, doc=None):
+            self.name = name
+            self.__doc__ = doc
+        def _fail(self, *args, **kwargs):
+            raise RuntimeError('signalling support is unavailable '
+                               'because the blinker library is '
+                               'not installed.')
+        send = lambda *a, **kw: None
+        connect = disconnect = has_receivers_for = receivers_for = \
+            temporarily_connected_to = connected_to = _fail
+        del _fail
+
+# The namespace for code signals.  If you are not Flask code, do
+# not put signals in here.  Create your own namespace instead.
+_signals = Namespace()
+
+
+# Core signals.  For usage examples grep the source code or consult
+# the API documentation in docs/api.rst as well as docs/signals.rst
+template_rendered = _signals.signal('template-rendered')
+before_render_template = _signals.signal('before-render-template')
+request_started = _signals.signal('request-started')
+request_finished = _signals.signal('request-finished')
+request_tearing_down = _signals.signal('request-tearing-down')
+got_request_exception = _signals.signal('got-request-exception')
+appcontext_tearing_down = _signals.signal('appcontext-tearing-down')
+appcontext_pushed = _signals.signal('appcontext-pushed')
+appcontext_popped = _signals.signal('appcontext-popped')
+message_flashed = _signals.signal('message-flashed')
diff --git a/python/flask/templating.py b/python/flask/templating.py
new file mode 100644
index 0000000..0240200
--- /dev/null
+++ b/python/flask/templating.py
@@ -0,0 +1,150 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.templating
+    ~~~~~~~~~~~~~~~~
+
+    Implements the bridge to Jinja2.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from jinja2 import BaseLoader, Environment as BaseEnvironment, \
+     TemplateNotFound
+
+from .globals import _request_ctx_stack, _app_ctx_stack
+from .signals import template_rendered, before_render_template
+
+
+def _default_template_ctx_processor():
+    """Default template context processor.  Injects `request`,
+    `session` and `g`.
+    """
+    reqctx = _request_ctx_stack.top
+    appctx = _app_ctx_stack.top
+    rv = {}
+    if appctx is not None:
+        rv['g'] = appctx.g
+    if reqctx is not None:
+        rv['request'] = reqctx.request
+        rv['session'] = reqctx.session
+    return rv
+
+
+class Environment(BaseEnvironment):
+    """Works like a regular Jinja2 environment but has some additional
+    knowledge of how Flask's blueprint works so that it can prepend the
+    name of the blueprint to referenced templates if necessary.
+    """
+
+    def __init__(self, app, **options):
+        if 'loader' not in options:
+            options['loader'] = app.create_global_jinja_loader()
+        BaseEnvironment.__init__(self, **options)
+        self.app = app
+
+
+class DispatchingJinjaLoader(BaseLoader):
+    """A loader that looks for templates in the application and all
+    the blueprint folders.
+    """
+
+    def __init__(self, app):
+        self.app = app
+
+    def get_source(self, environment, template):
+        if self.app.config['EXPLAIN_TEMPLATE_LOADING']:
+            return self._get_source_explained(environment, template)
+        return self._get_source_fast(environment, template)
+
+    def _get_source_explained(self, environment, template):
+        attempts = []
+        trv = None
+
+        for srcobj, loader in self._iter_loaders(template):
+            try:
+                rv = loader.get_source(environment, template)
+                if trv is None:
+                    trv = rv
+            except TemplateNotFound:
+                rv = None
+            attempts.append((loader, srcobj, rv))
+
+        from .debughelpers import explain_template_loading_attempts
+        explain_template_loading_attempts(self.app, template, attempts)
+
+        if trv is not None:
+            return trv
+        raise TemplateNotFound(template)
+
+    def _get_source_fast(self, environment, template):
+        for srcobj, loader in self._iter_loaders(template):
+            try:
+                return loader.get_source(environment, template)
+            except TemplateNotFound:
+                continue
+        raise TemplateNotFound(template)
+
+    def _iter_loaders(self, template):
+        loader = self.app.jinja_loader
+        if loader is not None:
+            yield self.app, loader
+
+        for blueprint in self.app.iter_blueprints():
+            loader = blueprint.jinja_loader
+            if loader is not None:
+                yield blueprint, loader
+
+    def list_templates(self):
+        result = set()
+        loader = self.app.jinja_loader
+        if loader is not None:
+            result.update(loader.list_templates())
+
+        for blueprint in self.app.iter_blueprints():
+            loader = blueprint.jinja_loader
+            if loader is not None:
+                for template in loader.list_templates():
+                    result.add(template)
+
+        return list(result)
+
+
+def _render(template, context, app):
+    """Renders the template and fires the signal"""
+
+    before_render_template.send(app, template=template, context=context)
+    rv = template.render(context)
+    template_rendered.send(app, template=template, context=context)
+    return rv
+
+
+def render_template(template_name_or_list, **context):
+    """Renders a template from the template folder with the given
+    context.
+
+    :param template_name_or_list: the name of the template to be
+                                  rendered, or an iterable with template names
+                                  the first one existing will be rendered
+    :param context: the variables that should be available in the
+                    context of the template.
+    """
+    ctx = _app_ctx_stack.top
+    ctx.app.update_template_context(context)
+    return _render(ctx.app.jinja_env.get_or_select_template(template_name_or_list),
+                   context, ctx.app)
+
+
+def render_template_string(source, **context):
+    """Renders a template from the given template source string
+    with the given context. Template variables will be autoescaped.
+
+    :param source: the source code of the template to be
+                   rendered
+    :param context: the variables that should be available in the
+                    context of the template.
+    """
+    ctx = _app_ctx_stack.top
+    ctx.app.update_template_context(context)
+    return _render(ctx.app.jinja_env.from_string(source),
+                   context, ctx.app)
diff --git a/python/flask/testing.py b/python/flask/testing.py
new file mode 100644
index 0000000..114c5cc
--- /dev/null
+++ b/python/flask/testing.py
@@ -0,0 +1,246 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.testing
+    ~~~~~~~~~~~~~
+
+    Implements test support helpers.  This module is lazily imported
+    and usually not used in production environments.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+import werkzeug
+from contextlib import contextmanager
+
+from click.testing import CliRunner
+from flask.cli import ScriptInfo
+from werkzeug.test import Client, EnvironBuilder
+from flask import _request_ctx_stack
+from flask.json import dumps as json_dumps
+from werkzeug.urls import url_parse
+
+
+def make_test_environ_builder(
+    app, path='/', base_url=None, subdomain=None, url_scheme=None,
+    *args, **kwargs
+):
+    """Create a :class:`~werkzeug.test.EnvironBuilder`, taking some
+    defaults from the application.
+
+    :param app: The Flask application to configure the environment from.
+    :param path: URL path being requested.
+    :param base_url: Base URL where the app is being served, which
+        ``path`` is relative to. If not given, built from
+        :data:`PREFERRED_URL_SCHEME`, ``subdomain``,
+        :data:`SERVER_NAME`, and :data:`APPLICATION_ROOT`.
+    :param subdomain: Subdomain name to append to :data:`SERVER_NAME`.
+    :param url_scheme: Scheme to use instead of
+        :data:`PREFERRED_URL_SCHEME`.
+    :param json: If given, this is serialized as JSON and passed as
+        ``data``. Also defaults ``content_type`` to
+        ``application/json``.
+    :param args: other positional arguments passed to
+        :class:`~werkzeug.test.EnvironBuilder`.
+    :param kwargs: other keyword arguments passed to
+        :class:`~werkzeug.test.EnvironBuilder`.
+    """
+
+    assert (
+        not (base_url or subdomain or url_scheme)
+        or (base_url is not None) != bool(subdomain or url_scheme)
+    ), 'Cannot pass "subdomain" or "url_scheme" with "base_url".'
+
+    if base_url is None:
+        http_host = app.config.get('SERVER_NAME') or 'localhost'
+        app_root = app.config['APPLICATION_ROOT']
+
+        if subdomain:
+            http_host = '{0}.{1}'.format(subdomain, http_host)
+
+        if url_scheme is None:
+            url_scheme = app.config['PREFERRED_URL_SCHEME']
+
+        url = url_parse(path)
+        base_url = '{scheme}://{netloc}/{path}'.format(
+            scheme=url.scheme or url_scheme,
+            netloc=url.netloc or http_host,
+            path=app_root.lstrip('/')
+        )
+        path = url.path
+
+        if url.query:
+            sep = b'?' if isinstance(url.query, bytes) else '?'
+            path += sep + url.query
+
+    # TODO use EnvironBuilder.json_dumps once we require Werkzeug 0.15
+    if 'json' in kwargs:
+        assert 'data' not in kwargs, "Client cannot provide both 'json' and 'data'."
+        kwargs['data'] = json_dumps(kwargs.pop('json'), app=app)
+
+        if 'content_type' not in kwargs:
+            kwargs['content_type'] = 'application/json'
+
+    return EnvironBuilder(path, base_url, *args, **kwargs)
+
+
+class FlaskClient(Client):
+    """Works like a regular Werkzeug test client but has some knowledge about
+    how Flask works to defer the cleanup of the request context stack to the
+    end of a ``with`` body when used in a ``with`` statement.  For general
+    information about how to use this class refer to
+    :class:`werkzeug.test.Client`.
+
+    .. versionchanged:: 0.12
+       `app.test_client()` includes preset default environment, which can be
+       set after instantiation of the `app.test_client()` object in
+       `client.environ_base`.
+
+    Basic usage is outlined in the :ref:`testing` chapter.
+    """
+
+    preserve_context = False
+
+    def __init__(self, *args, **kwargs):
+        super(FlaskClient, self).__init__(*args, **kwargs)
+        self.environ_base = {
+            "REMOTE_ADDR": "127.0.0.1",
+            "HTTP_USER_AGENT": "werkzeug/" + werkzeug.__version__
+        }
+
+    @contextmanager
+    def session_transaction(self, *args, **kwargs):
+        """When used in combination with a ``with`` statement this opens a
+        session transaction.  This can be used to modify the session that
+        the test client uses.  Once the ``with`` block is left the session is
+        stored back.
+
+        ::
+
+            with client.session_transaction() as session:
+                session['value'] = 42
+
+        Internally this is implemented by going through a temporary test
+        request context and since session handling could depend on
+        request variables this function accepts the same arguments as
+        :meth:`~flask.Flask.test_request_context` which are directly
+        passed through.
+        """
+        if self.cookie_jar is None:
+            raise RuntimeError('Session transactions only make sense '
+                               'with cookies enabled.')
+        app = self.application
+        environ_overrides = kwargs.setdefault('environ_overrides', {})
+        self.cookie_jar.inject_wsgi(environ_overrides)
+        outer_reqctx = _request_ctx_stack.top
+        with app.test_request_context(*args, **kwargs) as c:
+            session_interface = app.session_interface
+            sess = session_interface.open_session(app, c.request)
+            if sess is None:
+                raise RuntimeError('Session backend did not open a session. '
+                                   'Check the configuration')
+
+            # Since we have to open a new request context for the session
+            # handling we want to make sure that we hide out own context
+            # from the caller.  By pushing the original request context
+            # (or None) on top of this and popping it we get exactly that
+            # behavior.  It's important to not use the push and pop
+            # methods of the actual request context object since that would
+            # mean that cleanup handlers are called
+            _request_ctx_stack.push(outer_reqctx)
+            try:
+                yield sess
+            finally:
+                _request_ctx_stack.pop()
+
+            resp = app.response_class()
+            if not session_interface.is_null_session(sess):
+                session_interface.save_session(app, sess, resp)
+            headers = resp.get_wsgi_headers(c.request.environ)
+            self.cookie_jar.extract_wsgi(c.request.environ, headers)
+
+    def open(self, *args, **kwargs):
+        as_tuple = kwargs.pop('as_tuple', False)
+        buffered = kwargs.pop('buffered', False)
+        follow_redirects = kwargs.pop('follow_redirects', False)
+
+        if (
+            not kwargs and len(args) == 1
+            and isinstance(args[0], (EnvironBuilder, dict))
+        ):
+            environ = self.environ_base.copy()
+
+            if isinstance(args[0], EnvironBuilder):
+                environ.update(args[0].get_environ())
+            else:
+                environ.update(args[0])
+
+            environ['flask._preserve_context'] = self.preserve_context
+        else:
+            kwargs.setdefault('environ_overrides', {}) \
+                ['flask._preserve_context'] = self.preserve_context
+            kwargs.setdefault('environ_base', self.environ_base)
+            builder = make_test_environ_builder(
+                self.application, *args, **kwargs
+            )
+
+            try:
+                environ = builder.get_environ()
+            finally:
+                builder.close()
+
+        return Client.open(
+            self, environ,
+            as_tuple=as_tuple,
+            buffered=buffered,
+            follow_redirects=follow_redirects
+        )
+
+    def __enter__(self):
+        if self.preserve_context:
+            raise RuntimeError('Cannot nest client invocations')
+        self.preserve_context = True
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.preserve_context = False
+
+        # on exit we want to clean up earlier.  Normally the request context
+        # stays preserved until the next request in the same thread comes
+        # in.  See RequestGlobals.push() for the general behavior.
+        top = _request_ctx_stack.top
+        if top is not None and top.preserved:
+            top.pop()
+
+
+class FlaskCliRunner(CliRunner):
+    """A :class:`~click.testing.CliRunner` for testing a Flask app's
+    CLI commands. Typically created using
+    :meth:`~flask.Flask.test_cli_runner`. See :ref:`testing-cli`.
+    """
+    def __init__(self, app, **kwargs):
+        self.app = app
+        super(FlaskCliRunner, self).__init__(**kwargs)
+
+    def invoke(self, cli=None, args=None, **kwargs):
+        """Invokes a CLI command in an isolated environment. See
+        :meth:`CliRunner.invoke <click.testing.CliRunner.invoke>` for
+        full method documentation. See :ref:`testing-cli` for examples.
+
+        If the ``obj`` argument is not given, passes an instance of
+        :class:`~flask.cli.ScriptInfo` that knows how to load the Flask
+        app being tested.
+
+        :param cli: Command object to invoke. Default is the app's
+            :attr:`~flask.app.Flask.cli` group.
+        :param args: List of strings to invoke the command with.
+
+        :return: a :class:`~click.testing.Result` object.
+        """
+        if cli is None:
+            cli = self.app.cli
+
+        if 'obj' not in kwargs:
+            kwargs['obj'] = ScriptInfo(create_app=lambda: self.app)
+
+        return super(FlaskCliRunner, self).invoke(cli, args, **kwargs)
diff --git a/python/flask/views.py b/python/flask/views.py
new file mode 100644
index 0000000..1f2c997
--- /dev/null
+++ b/python/flask/views.py
@@ -0,0 +1,158 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.views
+    ~~~~~~~~~~~
+
+    This module provides class-based views inspired by the ones in Django.
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from .globals import request
+from ._compat import with_metaclass
+
+
+http_method_funcs = frozenset(['get', 'post', 'head', 'options',
+                               'delete', 'put', 'trace', 'patch'])
+
+
+class View(object):
+    """Alternative way to use view functions.  A subclass has to implement
+    :meth:`dispatch_request` which is called with the view arguments from
+    the URL routing system.  If :attr:`methods` is provided the methods
+    do not have to be passed to the :meth:`~flask.Flask.add_url_rule`
+    method explicitly::
+
+        class MyView(View):
+            methods = ['GET']
+
+            def dispatch_request(self, name):
+                return 'Hello %s!' % name
+
+        app.add_url_rule('/hello/<name>', view_func=MyView.as_view('myview'))
+
+    When you want to decorate a pluggable view you will have to either do that
+    when the view function is created (by wrapping the return value of
+    :meth:`as_view`) or you can use the :attr:`decorators` attribute::
+
+        class SecretView(View):
+            methods = ['GET']
+            decorators = [superuser_required]
+
+            def dispatch_request(self):
+                ...
+
+    The decorators stored in the decorators list are applied one after another
+    when the view function is created.  Note that you can *not* use the class
+    based decorators since those would decorate the view class and not the
+    generated view function!
+    """
+
+    #: A list of methods this view can handle.
+    methods = None
+
+    #: Setting this disables or force-enables the automatic options handling.
+    provide_automatic_options = None
+
+    #: The canonical way to decorate class-based views is to decorate the
+    #: return value of as_view().  However since this moves parts of the
+    #: logic from the class declaration to the place where it's hooked
+    #: into the routing system.
+    #:
+    #: You can place one or more decorators in this list and whenever the
+    #: view function is created the result is automatically decorated.
+    #:
+    #: .. versionadded:: 0.8
+    decorators = ()
+
+    def dispatch_request(self):
+        """Subclasses have to override this method to implement the
+        actual view function code.  This method is called with all
+        the arguments from the URL rule.
+        """
+        raise NotImplementedError()
+
+    @classmethod
+    def as_view(cls, name, *class_args, **class_kwargs):
+        """Converts the class into an actual view function that can be used
+        with the routing system.  Internally this generates a function on the
+        fly which will instantiate the :class:`View` on each request and call
+        the :meth:`dispatch_request` method on it.
+
+        The arguments passed to :meth:`as_view` are forwarded to the
+        constructor of the class.
+        """
+        def view(*args, **kwargs):
+            self = view.view_class(*class_args, **class_kwargs)
+            return self.dispatch_request(*args, **kwargs)
+
+        if cls.decorators:
+            view.__name__ = name
+            view.__module__ = cls.__module__
+            for decorator in cls.decorators:
+                view = decorator(view)
+
+        # We attach the view class to the view function for two reasons:
+        # first of all it allows us to easily figure out what class-based
+        # view this thing came from, secondly it's also used for instantiating
+        # the view class so you can actually replace it with something else
+        # for testing purposes and debugging.
+        view.view_class = cls
+        view.__name__ = name
+        view.__doc__ = cls.__doc__
+        view.__module__ = cls.__module__
+        view.methods = cls.methods
+        view.provide_automatic_options = cls.provide_automatic_options
+        return view
+
+
+class MethodViewType(type):
+    """Metaclass for :class:`MethodView` that determines what methods the view
+    defines.
+    """
+
+    def __init__(cls, name, bases, d):
+        super(MethodViewType, cls).__init__(name, bases, d)
+
+        if 'methods' not in d:
+            methods = set()
+
+            for key in http_method_funcs:
+                if hasattr(cls, key):
+                    methods.add(key.upper())
+
+            # If we have no method at all in there we don't want to add a
+            # method list. This is for instance the case for the base class
+            # or another subclass of a base method view that does not introduce
+            # new methods.
+            if methods:
+                cls.methods = methods
+
+
+class MethodView(with_metaclass(MethodViewType, View)):
+    """A class-based view that dispatches request methods to the corresponding
+    class methods. For example, if you implement a ``get`` method, it will be
+    used to handle ``GET`` requests. ::
+
+        class CounterAPI(MethodView):
+            def get(self):
+                return session.get('counter', 0)
+
+            def post(self):
+                session['counter'] = session.get('counter', 0) + 1
+                return 'OK'
+
+        app.add_url_rule('/counter', view_func=CounterAPI.as_view('counter'))
+    """
+
+    def dispatch_request(self, *args, **kwargs):
+        meth = getattr(self, request.method.lower(), None)
+
+        # If the request method is HEAD and we don't have a handler for it
+        # retry with GET.
+        if meth is None and request.method == 'HEAD':
+            meth = getattr(self, 'get', None)
+
+        assert meth is not None, 'Unimplemented method %r' % request.method
+        return meth(*args, **kwargs)
diff --git a/python/flask/wrappers.py b/python/flask/wrappers.py
new file mode 100644
index 0000000..12eff2c
--- /dev/null
+++ b/python/flask/wrappers.py
@@ -0,0 +1,216 @@
+# -*- coding: utf-8 -*-
+"""
+    flask.wrappers
+    ~~~~~~~~~~~~~~
+
+    Implements the WSGI wrappers (request and response).
+
+    :copyright: © 2010 by the Pallets team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from werkzeug.exceptions import BadRequest
+from werkzeug.wrappers import Request as RequestBase, Response as ResponseBase
+
+from flask import json
+from flask.globals import current_app
+
+
+class JSONMixin(object):
+    """Common mixin for both request and response objects to provide JSON
+    parsing capabilities.
+
+    .. versionadded:: 1.0
+    """
+
+    _cached_json = (Ellipsis, Ellipsis)
+
+    @property
+    def is_json(self):
+        """Check if the mimetype indicates JSON data, either
+        :mimetype:`application/json` or :mimetype:`application/*+json`.
+
+        .. versionadded:: 0.11
+        """
+        mt = self.mimetype
+        return (
+            mt == 'application/json'
+            or (mt.startswith('application/')) and mt.endswith('+json')
+        )
+
+    @property
+    def json(self):
+        """This will contain the parsed JSON data if the mimetype indicates
+        JSON (:mimetype:`application/json`, see :meth:`is_json`), otherwise it
+        will be ``None``.
+        """
+        return self.get_json()
+
+    def _get_data_for_json(self, cache):
+        return self.get_data(cache=cache)
+
+    def get_json(self, force=False, silent=False, cache=True):
+        """Parse and return the data as JSON. If the mimetype does not
+        indicate JSON (:mimetype:`application/json`, see
+        :meth:`is_json`), this returns ``None`` unless ``force`` is
+        true. If parsing fails, :meth:`on_json_loading_failed` is called
+        and its return value is used as the return value.
+
+        :param force: Ignore the mimetype and always try to parse JSON.
+        :param silent: Silence parsing errors and return ``None``
+            instead.
+        :param cache: Store the parsed JSON to return for subsequent
+            calls.
+        """
+        if cache and self._cached_json[silent] is not Ellipsis:
+            return self._cached_json[silent]
+
+        if not (force or self.is_json):
+            return None
+
+        data = self._get_data_for_json(cache=cache)
+
+        try:
+            rv = json.loads(data)
+        except ValueError as e:
+            if silent:
+                rv = None
+                if cache:
+                    normal_rv, _ = self._cached_json
+                    self._cached_json = (normal_rv, rv)
+            else:
+                rv = self.on_json_loading_failed(e)
+                if cache:
+                    _, silent_rv = self._cached_json
+                    self._cached_json = (rv, silent_rv)
+        else:
+            if cache:
+                self._cached_json = (rv, rv)
+
+        return rv
+
+    def on_json_loading_failed(self, e):
+        """Called if :meth:`get_json` parsing fails and isn't silenced. If
+        this method returns a value, it is used as the return value for
+        :meth:`get_json`. The default implementation raises a
+        :class:`BadRequest` exception.
+
+        .. versionchanged:: 0.10
+           Raise a :exc:`BadRequest` error instead of returning an error
+           message as JSON. If you want that behavior you can add it by
+           subclassing.
+
+        .. versionadded:: 0.8
+        """
+        if current_app is not None and current_app.debug:
+            raise BadRequest('Failed to decode JSON object: {0}'.format(e))
+
+        raise BadRequest()
+
+
+class Request(RequestBase, JSONMixin):
+    """The request object used by default in Flask.  Remembers the
+    matched endpoint and view arguments.
+
+    It is what ends up as :class:`~flask.request`.  If you want to replace
+    the request object used you can subclass this and set
+    :attr:`~flask.Flask.request_class` to your subclass.
+
+    The request object is a :class:`~werkzeug.wrappers.Request` subclass and
+    provides all of the attributes Werkzeug defines plus a few Flask
+    specific ones.
+    """
+
+    #: The internal URL rule that matched the request.  This can be
+    #: useful to inspect which methods are allowed for the URL from
+    #: a before/after handler (``request.url_rule.methods``) etc.
+    #: Though if the request's method was invalid for the URL rule,
+    #: the valid list is available in ``routing_exception.valid_methods``
+    #: instead (an attribute of the Werkzeug exception :exc:`~werkzeug.exceptions.MethodNotAllowed`)
+    #: because the request was never internally bound.
+    #:
+    #: .. versionadded:: 0.6
+    url_rule = None
+
+    #: A dict of view arguments that matched the request.  If an exception
+    #: happened when matching, this will be ``None``.
+    view_args = None
+
+    #: If matching the URL failed, this is the exception that will be
+    #: raised / was raised as part of the request handling.  This is
+    #: usually a :exc:`~werkzeug.exceptions.NotFound` exception or
+    #: something similar.
+    routing_exception = None
+
+    @property
+    def max_content_length(self):
+        """Read-only view of the ``MAX_CONTENT_LENGTH`` config key."""
+        if current_app:
+            return current_app.config['MAX_CONTENT_LENGTH']
+
+    @property
+    def endpoint(self):
+        """The endpoint that matched the request.  This in combination with
+        :attr:`view_args` can be used to reconstruct the same or a
+        modified URL.  If an exception happened when matching, this will
+        be ``None``.
+        """
+        if self.url_rule is not None:
+            return self.url_rule.endpoint
+
+    @property
+    def blueprint(self):
+        """The name of the current blueprint"""
+        if self.url_rule and '.' in self.url_rule.endpoint:
+            return self.url_rule.endpoint.rsplit('.', 1)[0]
+
+    def _load_form_data(self):
+        RequestBase._load_form_data(self)
+
+        # In debug mode we're replacing the files multidict with an ad-hoc
+        # subclass that raises a different error for key errors.
+        if (
+            current_app
+            and current_app.debug
+            and self.mimetype != 'multipart/form-data'
+            and not self.files
+        ):
+            from .debughelpers import attach_enctype_error_multidict
+            attach_enctype_error_multidict(self)
+
+
+class Response(ResponseBase, JSONMixin):
+    """The response object that is used by default in Flask.  Works like the
+    response object from Werkzeug but is set to have an HTML mimetype by
+    default.  Quite often you don't have to create this object yourself because
+    :meth:`~flask.Flask.make_response` will take care of that for you.
+
+    If you want to replace the response object used you can subclass this and
+    set :attr:`~flask.Flask.response_class` to your subclass.
+
+    .. versionchanged:: 1.0
+        JSON support is added to the response, like the request. This is useful
+        when testing to get the test client response data as JSON.
+
+    .. versionchanged:: 1.0
+
+        Added :attr:`max_cookie_size`.
+    """
+
+    default_mimetype = 'text/html'
+
+    def _get_data_for_json(self, cache):
+        return self.get_data()
+
+    @property
+    def max_cookie_size(self):
+        """Read-only view of the :data:`MAX_COOKIE_SIZE` config key.
+
+        See :attr:`~werkzeug.wrappers.BaseResponse.max_cookie_size` in
+        Werkzeug's docs.
+        """
+        if current_app:
+            return current_app.config['MAX_COOKIE_SIZE']
+
+        # return Werkzeug's default when not in an app context
+        return super(Response, self).max_cookie_size
diff --git a/python/itsdangerous/__init__.py b/python/itsdangerous/__init__.py
new file mode 100644
index 0000000..0fcd8c1
--- /dev/null
+++ b/python/itsdangerous/__init__.py
@@ -0,0 +1,22 @@
+from ._json import json
+from .encoding import base64_decode
+from .encoding import base64_encode
+from .encoding import want_bytes
+from .exc import BadData
+from .exc import BadHeader
+from .exc import BadPayload
+from .exc import BadSignature
+from .exc import BadTimeSignature
+from .exc import SignatureExpired
+from .jws import JSONWebSignatureSerializer
+from .jws import TimedJSONWebSignatureSerializer
+from .serializer import Serializer
+from .signer import HMACAlgorithm
+from .signer import NoneAlgorithm
+from .signer import Signer
+from .timed import TimedSerializer
+from .timed import TimestampSigner
+from .url_safe import URLSafeSerializer
+from .url_safe import URLSafeTimedSerializer
+
+__version__ = "1.1.0"
diff --git a/python/itsdangerous/_compat.py b/python/itsdangerous/_compat.py
new file mode 100644
index 0000000..2291bce
--- /dev/null
+++ b/python/itsdangerous/_compat.py
@@ -0,0 +1,46 @@
+import decimal
+import hmac
+import numbers
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+if PY2:
+    from itertools import izip
+
+    text_type = unicode  # noqa: 821
+else:
+    izip = zip
+    text_type = str
+
+number_types = (numbers.Real, decimal.Decimal)
+
+
+def _constant_time_compare(val1, val2):
+    """Return ``True`` if the two strings are equal, ``False``
+    otherwise.
+
+    The time taken is independent of the number of characters that
+    match. Do not use this function for anything else than comparision
+    with known length targets.
+
+    This is should be implemented in C in order to get it completely
+    right.
+
+    This is an alias of :func:`hmac.compare_digest` on Python>=2.7,3.3.
+    """
+    len_eq = len(val1) == len(val2)
+    if len_eq:
+        result = 0
+        left = val1
+    else:
+        result = 1
+        left = val2
+    for x, y in izip(bytearray(left), bytearray(val2)):
+        result |= x ^ y
+    return result == 0
+
+
+# Starting with 2.7/3.3 the standard library has a c-implementation for
+# constant time string compares.
+constant_time_compare = getattr(hmac, "compare_digest", _constant_time_compare)
diff --git a/python/itsdangerous/_json.py b/python/itsdangerous/_json.py
new file mode 100644
index 0000000..426b36e
--- /dev/null
+++ b/python/itsdangerous/_json.py
@@ -0,0 +1,18 @@
+try:
+    import simplejson as json
+except ImportError:
+    import json
+
+
+class _CompactJSON(object):
+    """Wrapper around json module that strips whitespace."""
+
+    @staticmethod
+    def loads(payload):
+        return json.loads(payload)
+
+    @staticmethod
+    def dumps(obj, **kwargs):
+        kwargs.setdefault("ensure_ascii", False)
+        kwargs.setdefault("separators", (",", ":"))
+        return json.dumps(obj, **kwargs)
diff --git a/python/itsdangerous/encoding.py b/python/itsdangerous/encoding.py
new file mode 100644
index 0000000..1e28969
--- /dev/null
+++ b/python/itsdangerous/encoding.py
@@ -0,0 +1,49 @@
+import base64
+import string
+import struct
+
+from ._compat import text_type
+from .exc import BadData
+
+
+def want_bytes(s, encoding="utf-8", errors="strict"):
+    if isinstance(s, text_type):
+        s = s.encode(encoding, errors)
+    return s
+
+
+def base64_encode(string):
+    """Base64 encode a string of bytes or text. The resulting bytes are
+    safe to use in URLs.
+    """
+    string = want_bytes(string)
+    return base64.urlsafe_b64encode(string).rstrip(b"=")
+
+
+def base64_decode(string):
+    """Base64 decode a URL-safe string of bytes or text. The result is
+    bytes.
+    """
+    string = want_bytes(string, encoding="ascii", errors="ignore")
+    string += b"=" * (-len(string) % 4)
+
+    try:
+        return base64.urlsafe_b64decode(string)
+    except (TypeError, ValueError):
+        raise BadData("Invalid base64-encoded data")
+
+
+# The alphabet used by base64.urlsafe_*
+_base64_alphabet = (string.ascii_letters + string.digits + "-_=").encode("ascii")
+
+_int64_struct = struct.Struct(">Q")
+_int_to_bytes = _int64_struct.pack
+_bytes_to_int = _int64_struct.unpack
+
+
+def int_to_bytes(num):
+    return _int_to_bytes(num).lstrip(b"\x00")
+
+
+def bytes_to_int(bytestr):
+    return _bytes_to_int(bytestr.rjust(8, b"\x00"))[0]
diff --git a/python/itsdangerous/exc.py b/python/itsdangerous/exc.py
new file mode 100644
index 0000000..287d691
--- /dev/null
+++ b/python/itsdangerous/exc.py
@@ -0,0 +1,98 @@
+from ._compat import PY2
+from ._compat import text_type
+
+
+class BadData(Exception):
+    """Raised if bad data of any sort was encountered. This is the base
+    for all exceptions that itsdangerous defines.
+
+    .. versionadded:: 0.15
+    """
+
+    message = None
+
+    def __init__(self, message):
+        super(BadData, self).__init__(self, message)
+        self.message = message
+
+    def __str__(self):
+        return text_type(self.message)
+
+    if PY2:
+        __unicode__ = __str__
+
+        def __str__(self):
+            return self.__unicode__().encode("utf-8")
+
+
+class BadSignature(BadData):
+    """Raised if a signature does not match."""
+
+    def __init__(self, message, payload=None):
+        BadData.__init__(self, message)
+
+        #: The payload that failed the signature test. In some
+        #: situations you might still want to inspect this, even if
+        #: you know it was tampered with.
+        #:
+        #: .. versionadded:: 0.14
+        self.payload = payload
+
+
+class BadTimeSignature(BadSignature):
+    """Raised if a time-based signature is invalid. This is a subclass
+    of :class:`BadSignature`.
+    """
+
+    def __init__(self, message, payload=None, date_signed=None):
+        BadSignature.__init__(self, message, payload)
+
+        #: If the signature expired this exposes the date of when the
+        #: signature was created. This can be helpful in order to
+        #: tell the user how long a link has been gone stale.
+        #:
+        #: .. versionadded:: 0.14
+        self.date_signed = date_signed
+
+
+class SignatureExpired(BadTimeSignature):
+    """Raised if a signature timestamp is older than ``max_age``. This
+    is a subclass of :exc:`BadTimeSignature`.
+    """
+
+
+class BadHeader(BadSignature):
+    """Raised if a signed header is invalid in some form. This only
+    happens for serializers that have a header that goes with the
+    signature.
+
+    .. versionadded:: 0.24
+    """
+
+    def __init__(self, message, payload=None, header=None, original_error=None):
+        BadSignature.__init__(self, message, payload)
+
+        #: If the header is actually available but just malformed it
+        #: might be stored here.
+        self.header = header
+
+        #: If available, the error that indicates why the payload was
+        #: not valid. This might be ``None``.
+        self.original_error = original_error
+
+
+class BadPayload(BadData):
+    """Raised if a payload is invalid. This could happen if the payload
+    is loaded despite an invalid signature, or if there is a mismatch
+    between the serializer and deserializer. The original exception
+    that occurred during loading is stored on as :attr:`original_error`.
+
+    .. versionadded:: 0.15
+    """
+
+    def __init__(self, message, original_error=None):
+        BadData.__init__(self, message)
+
+        #: If available, the error that indicates why the payload was
+        #: not valid. This might be ``None``.
+        self.original_error = original_error
diff --git a/python/itsdangerous/jws.py b/python/itsdangerous/jws.py
new file mode 100644
index 0000000..92e9ec8
--- /dev/null
+++ b/python/itsdangerous/jws.py
@@ -0,0 +1,218 @@
+import hashlib
+import time
+from datetime import datetime
+
+from ._compat import number_types
+from ._json import _CompactJSON
+from ._json import json
+from .encoding import base64_decode
+from .encoding import base64_encode
+from .encoding import want_bytes
+from .exc import BadData
+from .exc import BadHeader
+from .exc import BadPayload
+from .exc import BadSignature
+from .exc import SignatureExpired
+from .serializer import Serializer
+from .signer import HMACAlgorithm
+from .signer import NoneAlgorithm
+
+
+class JSONWebSignatureSerializer(Serializer):
+    """This serializer implements JSON Web Signature (JWS) support. Only
+    supports the JWS Compact Serialization.
+    """
+
+    jws_algorithms = {
+        "HS256": HMACAlgorithm(hashlib.sha256),
+        "HS384": HMACAlgorithm(hashlib.sha384),
+        "HS512": HMACAlgorithm(hashlib.sha512),
+        "none": NoneAlgorithm(),
+    }
+
+    #: The default algorithm to use for signature generation
+    default_algorithm = "HS512"
+
+    default_serializer = _CompactJSON
+
+    def __init__(
+        self,
+        secret_key,
+        salt=None,
+        serializer=None,
+        serializer_kwargs=None,
+        signer=None,
+        signer_kwargs=None,
+        algorithm_name=None,
+    ):
+        Serializer.__init__(
+            self,
+            secret_key=secret_key,
+            salt=salt,
+            serializer=serializer,
+            serializer_kwargs=serializer_kwargs,
+            signer=signer,
+            signer_kwargs=signer_kwargs,
+        )
+        if algorithm_name is None:
+            algorithm_name = self.default_algorithm
+        self.algorithm_name = algorithm_name
+        self.algorithm = self.make_algorithm(algorithm_name)
+
+    def load_payload(self, payload, serializer=None, return_header=False):
+        payload = want_bytes(payload)
+        if b"." not in payload:
+            raise BadPayload('No "." found in value')
+        base64d_header, base64d_payload = payload.split(b".", 1)
+        try:
+            json_header = base64_decode(base64d_header)
+        except Exception as e:
+            raise BadHeader(
+                "Could not base64 decode the header because of an exception",
+                original_error=e,
+            )
+        try:
+            json_payload = base64_decode(base64d_payload)
+        except Exception as e:
+            raise BadPayload(
+                "Could not base64 decode the payload because of an exception",
+                original_error=e,
+            )
+        try:
+            header = Serializer.load_payload(self, json_header, serializer=json)
+        except BadData as e:
+            raise BadHeader(
+                "Could not unserialize header because it was malformed",
+                original_error=e,
+            )
+        if not isinstance(header, dict):
+            raise BadHeader("Header payload is not a JSON object", header=header)
+        payload = Serializer.load_payload(self, json_payload, serializer=serializer)
+        if return_header:
+            return payload, header
+        return payload
+
+    def dump_payload(self, header, obj):
+        base64d_header = base64_encode(
+            self.serializer.dumps(header, **self.serializer_kwargs)
+        )
+        base64d_payload = base64_encode(
+            self.serializer.dumps(obj, **self.serializer_kwargs)
+        )
+        return base64d_header + b"." + base64d_payload
+
+    def make_algorithm(self, algorithm_name):
+        try:
+            return self.jws_algorithms[algorithm_name]
+        except KeyError:
+            raise NotImplementedError("Algorithm not supported")
+
+    def make_signer(self, salt=None, algorithm=None):
+        if salt is None:
+            salt = self.salt
+        key_derivation = "none" if salt is None else None
+        if algorithm is None:
+            algorithm = self.algorithm
+        return self.signer(
+            self.secret_key,
+            salt=salt,
+            sep=".",
+            key_derivation=key_derivation,
+            algorithm=algorithm,
+        )
+
+    def make_header(self, header_fields):
+        header = header_fields.copy() if header_fields else {}
+        header["alg"] = self.algorithm_name
+        return header
+
+    def dumps(self, obj, salt=None, header_fields=None):
+        """Like :meth:`.Serializer.dumps` but creates a JSON Web
+        Signature. It also allows for specifying additional fields to be
+        included in the JWS header.
+        """
+        header = self.make_header(header_fields)
+        signer = self.make_signer(salt, self.algorithm)
+        return signer.sign(self.dump_payload(header, obj))
+
+    def loads(self, s, salt=None, return_header=False):
+        """Reverse of :meth:`dumps`. If requested via ``return_header``
+        it will return a tuple of payload and header.
+        """
+        payload, header = self.load_payload(
+            self.make_signer(salt, self.algorithm).unsign(want_bytes(s)),
+            return_header=True,
+        )
+        if header.get("alg") != self.algorithm_name:
+            raise BadHeader("Algorithm mismatch", header=header, payload=payload)
+        if return_header:
+            return payload, header
+        return payload
+
+    def loads_unsafe(self, s, salt=None, return_header=False):
+        kwargs = {"return_header": return_header}
+        return self._loads_unsafe_impl(s, salt, kwargs, kwargs)
+
+
+class TimedJSONWebSignatureSerializer(JSONWebSignatureSerializer):
+    """Works like the regular :class:`JSONWebSignatureSerializer` but
+    also records the time of the signing and can be used to expire
+    signatures.
+
+    JWS currently does not specify this behavior but it mentions a
+    possible extension like this in the spec. Expiry date is encoded
+    into the header similar to what's specified in `draft-ietf-oauth
+    -json-web-token <http://self-issued.info/docs/draft-ietf-oauth-json
+    -web-token.html#expDef>`_.
+    """
+
+    DEFAULT_EXPIRES_IN = 3600
+
+    def __init__(self, secret_key, expires_in=None, **kwargs):
+        JSONWebSignatureSerializer.__init__(self, secret_key, **kwargs)
+        if expires_in is None:
+            expires_in = self.DEFAULT_EXPIRES_IN
+        self.expires_in = expires_in
+
+    def make_header(self, header_fields):
+        header = JSONWebSignatureSerializer.make_header(self, header_fields)
+        iat = self.now()
+        exp = iat + self.expires_in
+        header["iat"] = iat
+        header["exp"] = exp
+        return header
+
+    def loads(self, s, salt=None, return_header=False):
+        payload, header = JSONWebSignatureSerializer.loads(
+            self, s, salt, return_header=True
+        )
+
+        if "exp" not in header:
+            raise BadSignature("Missing expiry date", payload=payload)
+
+        int_date_error = BadHeader("Expiry date is not an IntDate", payload=payload)
+        try:
+            header["exp"] = int(header["exp"])
+        except ValueError:
+            raise int_date_error
+        if header["exp"] < 0:
+            raise int_date_error
+
+        if header["exp"] < self.now():
+            raise SignatureExpired(
+                "Signature expired",
+                payload=payload,
+                date_signed=self.get_issue_date(header),
+            )
+
+        if return_header:
+            return payload, header
+        return payload
+
+    def get_issue_date(self, header):
+        rv = header.get("iat")
+        if isinstance(rv, number_types):
+            return datetime.utcfromtimestamp(int(rv))
+
+    def now(self):
+        return int(time.time())
diff --git a/python/itsdangerous/serializer.py b/python/itsdangerous/serializer.py
new file mode 100644
index 0000000..12c20f4
--- /dev/null
+++ b/python/itsdangerous/serializer.py
@@ -0,0 +1,233 @@
+import hashlib
+
+from ._compat import text_type
+from ._json import json
+from .encoding import want_bytes
+from .exc import BadPayload
+from .exc import BadSignature
+from .signer import Signer
+
+
+def is_text_serializer(serializer):
+    """Checks whether a serializer generates text or binary."""
+    return isinstance(serializer.dumps({}), text_type)
+
+
+class Serializer(object):
+    """This class provides a serialization interface on top of the
+    signer. It provides a similar API to json/pickle and other modules
+    but is structured differently internally. If you want to change the
+    underlying implementation for parsing and loading you have to
+    override the :meth:`load_payload` and :meth:`dump_payload`
+    functions.
+
+    This implementation uses simplejson if available for dumping and
+    loading and will fall back to the standard library's json module if
+    it's not available.
+
+    You do not need to subclass this class in order to switch out or
+    customize the :class:`.Signer`. You can instead pass a different
+    class to the constructor as well as keyword arguments as a dict that
+    should be forwarded.
+
+    .. code-block:: python
+
+        s = Serializer(signer_kwargs={'key_derivation': 'hmac'})
+
+    You may want to upgrade the signing parameters without invalidating
+    existing signatures that are in use. Fallback signatures can be
+    given that will be tried if unsigning with the current signer fails.
+
+    Fallback signers can be defined by providing a list of
+    ``fallback_signers``. Each item can be one of the following: a
+    signer class (which is instantiated with ``signer_kwargs``,
+    ``salt``, and ``secret_key``), a tuple
+    ``(signer_class, signer_kwargs)``, or a dict of ``signer_kwargs``.
+
+    For example, this is a serializer that signs using SHA-512, but will
+    unsign using either SHA-512 or SHA1:
+
+    .. code-block:: python
+
+        s = Serializer(
+            signer_kwargs={"digest_method": hashlib.sha512},
+            fallback_signers=[{"digest_method": hashlib.sha1}]
+        )
+
+    .. versionchanged:: 0.14:
+        The ``signer`` and ``signer_kwargs`` parameters were added to
+        the constructor.
+
+    .. versionchanged:: 1.1.0:
+        Added support for ``fallback_signers`` and configured a default
+        SHA-512 fallback. This fallback is for users who used the yanked
+        1.0.0 release which defaulted to SHA-512.
+    """
+
+    #: If a serializer module or class is not passed to the constructor
+    #: this one is picked up. This currently defaults to :mod:`json`.
+    default_serializer = json
+
+    #: The default :class:`Signer` class that is being used by this
+    #: serializer.
+    #:
+    #: .. versionadded:: 0.14
+    default_signer = Signer
+
+    #: The default fallback signers.
+    default_fallback_signers = [{"digest_method": hashlib.sha512}]
+
+    def __init__(
+        self,
+        secret_key,
+        salt=b"itsdangerous",
+        serializer=None,
+        serializer_kwargs=None,
+        signer=None,
+        signer_kwargs=None,
+        fallback_signers=None,
+    ):
+        self.secret_key = want_bytes(secret_key)
+        self.salt = want_bytes(salt)
+        if serializer is None:
+            serializer = self.default_serializer
+        self.serializer = serializer
+        self.is_text_serializer = is_text_serializer(serializer)
+        if signer is None:
+            signer = self.default_signer
+        self.signer = signer
+        self.signer_kwargs = signer_kwargs or {}
+        if fallback_signers is None:
+            fallback_signers = list(self.default_fallback_signers or ())
+        self.fallback_signers = fallback_signers
+        self.serializer_kwargs = serializer_kwargs or {}
+
+    def load_payload(self, payload, serializer=None):
+        """Loads the encoded object. This function raises
+        :class:`.BadPayload` if the payload is not valid. The
+        ``serializer`` parameter can be used to override the serializer
+        stored on the class. The encoded ``payload`` should always be
+        bytes.
+        """
+        if serializer is None:
+            serializer = self.serializer
+            is_text = self.is_text_serializer
+        else:
+            is_text = is_text_serializer(serializer)
+        try:
+            if is_text:
+                payload = payload.decode("utf-8")
+            return serializer.loads(payload)
+        except Exception as e:
+            raise BadPayload(
+                "Could not load the payload because an exception"
+                " occurred on unserializing the data.",
+                original_error=e,
+            )
+
+    def dump_payload(self, obj):
+        """Dumps the encoded object. The return value is always bytes.
+        If the internal serializer returns text, the value will be
+        encoded as UTF-8.
+        """
+        return want_bytes(self.serializer.dumps(obj, **self.serializer_kwargs))
+
+    def make_signer(self, salt=None):
+        """Creates a new instance of the signer to be used. The default
+        implementation uses the :class:`.Signer` base class.
+        """
+        if salt is None:
+            salt = self.salt
+        return self.signer(self.secret_key, salt=salt, **self.signer_kwargs)
+
+    def iter_unsigners(self, salt=None):
+        """Iterates over all signers to be tried for unsigning. Starts
+        with the configured signer, then constructs each signer
+        specified in ``fallback_signers``.
+        """
+        if salt is None:
+            salt = self.salt
+        yield self.make_signer(salt)
+        for fallback in self.fallback_signers:
+            if type(fallback) is dict:
+                kwargs = fallback
+                fallback = self.signer
+            elif type(fallback) is tuple:
+                fallback, kwargs = fallback
+            else:
+                kwargs = self.signer_kwargs
+            yield fallback(self.secret_key, salt=salt, **kwargs)
+
+    def dumps(self, obj, salt=None):
+        """Returns a signed string serialized with the internal
+        serializer. The return value can be either a byte or unicode
+        string depending on the format of the internal serializer.
+        """
+        payload = want_bytes(self.dump_payload(obj))
+        rv = self.make_signer(salt).sign(payload)
+        if self.is_text_serializer:
+            rv = rv.decode("utf-8")
+        return rv
+
+    def dump(self, obj, f, salt=None):
+        """Like :meth:`dumps` but dumps into a file. The file handle has
+        to be compatible with what the internal serializer expects.
+        """
+        f.write(self.dumps(obj, salt))
+
+    def loads(self, s, salt=None):
+        """Reverse of :meth:`dumps`. Raises :exc:`.BadSignature` if the
+        signature validation fails.
+        """
+        s = want_bytes(s)
+        last_exception = None
+        for signer in self.iter_unsigners(salt):
+            try:
+                return self.load_payload(signer.unsign(s))
+            except BadSignature as err:
+                last_exception = err
+        raise last_exception
+
+    def load(self, f, salt=None):
+        """Like :meth:`loads` but loads from a file."""
+        return self.loads(f.read(), salt)
+
+    def loads_unsafe(self, s, salt=None):
+        """Like :meth:`loads` but without verifying the signature. This
+        is potentially very dangerous to use depending on how your
+        serializer works. The return value is ``(signature_valid,
+        payload)`` instead of just the payload. The first item will be a
+        boolean that indicates if the signature is valid. This function
+        never fails.
+
+        Use it for debugging only and if you know that your serializer
+        module is not exploitable (for example, do not use it with a
+        pickle serializer).
+
+        .. versionadded:: 0.15
+        """
+        return self._loads_unsafe_impl(s, salt)
+
+    def _loads_unsafe_impl(self, s, salt, load_kwargs=None, load_payload_kwargs=None):
+        """Low level helper function to implement :meth:`loads_unsafe`
+        in serializer subclasses.
+        """
+        try:
+            return True, self.loads(s, salt=salt, **(load_kwargs or {}))
+        except BadSignature as e:
+            if e.payload is None:
+                return False, None
+            try:
+                return (
+                    False,
+                    self.load_payload(e.payload, **(load_payload_kwargs or {})),
+                )
+            except BadPayload:
+                return False, None
+
+    def load_unsafe(self, f, *args, **kwargs):
+        """Like :meth:`loads_unsafe` but loads from a file.
+
+        .. versionadded:: 0.15
+        """
+        return self.loads_unsafe(f.read(), *args, **kwargs)
diff --git a/python/itsdangerous/signer.py b/python/itsdangerous/signer.py
new file mode 100644
index 0000000..6bddc03
--- /dev/null
+++ b/python/itsdangerous/signer.py
@@ -0,0 +1,179 @@
+import hashlib
+import hmac
+
+from ._compat import constant_time_compare
+from .encoding import _base64_alphabet
+from .encoding import base64_decode
+from .encoding import base64_encode
+from .encoding import want_bytes
+from .exc import BadSignature
+
+
+class SigningAlgorithm(object):
+    """Subclasses must implement :meth:`get_signature` to provide
+    signature generation functionality.
+    """
+
+    def get_signature(self, key, value):
+        """Returns the signature for the given key and value."""
+        raise NotImplementedError()
+
+    def verify_signature(self, key, value, sig):
+        """Verifies the given signature matches the expected
+        signature.
+        """
+        return constant_time_compare(sig, self.get_signature(key, value))
+
+
+class NoneAlgorithm(SigningAlgorithm):
+    """Provides an algorithm that does not perform any signing and
+    returns an empty signature.
+    """
+
+    def get_signature(self, key, value):
+        return b""
+
+
+class HMACAlgorithm(SigningAlgorithm):
+    """Provides signature generation using HMACs."""
+
+    #: The digest method to use with the MAC algorithm. This defaults to
+    #: SHA1, but can be changed to any other function in the hashlib
+    #: module.
+    default_digest_method = staticmethod(hashlib.sha1)
+
+    def __init__(self, digest_method=None):
+        if digest_method is None:
+            digest_method = self.default_digest_method
+        self.digest_method = digest_method
+
+    def get_signature(self, key, value):
+        mac = hmac.new(key, msg=value, digestmod=self.digest_method)
+        return mac.digest()
+
+
+class Signer(object):
+    """This class can sign and unsign bytes, validating the signature
+    provided.
+
+    Salt can be used to namespace the hash, so that a signed string is
+    only valid for a given namespace. Leaving this at the default value
+    or re-using a salt value across different parts of your application
+    where the same signed value in one part can mean something different
+    in another part is a security risk.
+
+    See :ref:`the-salt` for an example of what the salt is doing and how
+    you can utilize it.
+
+    .. versionadded:: 0.14
+        ``key_derivation`` and ``digest_method`` were added as arguments
+        to the class constructor.
+
+    .. versionadded:: 0.18
+        ``algorithm`` was added as an argument to the class constructor.
+    """
+
+    #: The digest method to use for the signer.  This defaults to
+    #: SHA1 but can be changed to any other function in the hashlib
+    #: module.
+    #:
+    #: .. versionadded:: 0.14
+    default_digest_method = staticmethod(hashlib.sha1)
+
+    #: Controls how the key is derived. The default is Django-style
+    #: concatenation. Possible values are ``concat``, ``django-concat``
+    #: and ``hmac``. This is used for deriving a key from the secret key
+    #: with an added salt.
+    #:
+    #: .. versionadded:: 0.14
+    default_key_derivation = "django-concat"
+
+    def __init__(
+        self,
+        secret_key,
+        salt=None,
+        sep=".",
+        key_derivation=None,
+        digest_method=None,
+        algorithm=None,
+    ):
+        self.secret_key = want_bytes(secret_key)
+        self.sep = want_bytes(sep)
+        if self.sep in _base64_alphabet:
+            raise ValueError(
+                "The given separator cannot be used because it may be"
+                " contained in the signature itself. Alphanumeric"
+                " characters and `-_=` must not be used."
+            )
+        self.salt = "itsdangerous.Signer" if salt is None else salt
+        if key_derivation is None:
+            key_derivation = self.default_key_derivation
+        self.key_derivation = key_derivation
+        if digest_method is None:
+            digest_method = self.default_digest_method
+        self.digest_method = digest_method
+        if algorithm is None:
+            algorithm = HMACAlgorithm(self.digest_method)
+        self.algorithm = algorithm
+
+    def derive_key(self):
+        """This method is called to derive the key. The default key
+        derivation choices can be overridden here. Key derivation is not
+        intended to be used as a security method to make a complex key
+        out of a short password. Instead you should use large random
+        secret keys.
+        """
+        salt = want_bytes(self.salt)
+        if self.key_derivation == "concat":
+            return self.digest_method(salt + self.secret_key).digest()
+        elif self.key_derivation == "django-concat":
+            return self.digest_method(salt + b"signer" + self.secret_key).digest()
+        elif self.key_derivation == "hmac":
+            mac = hmac.new(self.secret_key, digestmod=self.digest_method)
+            mac.update(salt)
+            return mac.digest()
+        elif self.key_derivation == "none":
+            return self.secret_key
+        else:
+            raise TypeError("Unknown key derivation method")
+
+    def get_signature(self, value):
+        """Returns the signature for the given value."""
+        value = want_bytes(value)
+        key = self.derive_key()
+        sig = self.algorithm.get_signature(key, value)
+        return base64_encode(sig)
+
+    def sign(self, value):
+        """Signs the given string."""
+        return want_bytes(value) + want_bytes(self.sep) + self.get_signature(value)
+
+    def verify_signature(self, value, sig):
+        """Verifies the signature for the given value."""
+        key = self.derive_key()
+        try:
+            sig = base64_decode(sig)
+        except Exception:
+            return False
+        return self.algorithm.verify_signature(key, value, sig)
+
+    def unsign(self, signed_value):
+        """Unsigns the given string."""
+        signed_value = want_bytes(signed_value)
+        sep = want_bytes(self.sep)
+        if sep not in signed_value:
+            raise BadSignature("No %r found in value" % self.sep)
+        value, sig = signed_value.rsplit(sep, 1)
+        if self.verify_signature(value, sig):
+            return value
+        raise BadSignature("Signature %r does not match" % sig, payload=value)
+
+    def validate(self, signed_value):
+        """Only validates the given signed value. Returns ``True`` if
+        the signature exists and is valid.
+        """
+        try:
+            self.unsign(signed_value)
+            return True
+        except BadSignature:
+            return False
diff --git a/python/itsdangerous/timed.py b/python/itsdangerous/timed.py
new file mode 100644
index 0000000..4c117e4
--- /dev/null
+++ b/python/itsdangerous/timed.py
@@ -0,0 +1,147 @@
+import time
+from datetime import datetime
+
+from ._compat import text_type
+from .encoding import base64_decode
+from .encoding import base64_encode
+from .encoding import bytes_to_int
+from .encoding import int_to_bytes
+from .encoding import want_bytes
+from .exc import BadSignature
+from .exc import BadTimeSignature
+from .exc import SignatureExpired
+from .serializer import Serializer
+from .signer import Signer
+
+
+class TimestampSigner(Signer):
+    """Works like the regular :class:`.Signer` but also records the time
+    of the signing and can be used to expire signatures. The
+    :meth:`unsign` method can raise :exc:`.SignatureExpired` if the
+    unsigning failed because the signature is expired.
+    """
+
+    def get_timestamp(self):
+        """Returns the current timestamp. The function must return an
+        integer.
+        """
+        return int(time.time())
+
+    def timestamp_to_datetime(self, ts):
+        """Used to convert the timestamp from :meth:`get_timestamp` into
+        a datetime object.
+        """
+        return datetime.utcfromtimestamp(ts)
+
+    def sign(self, value):
+        """Signs the given string and also attaches time information."""
+        value = want_bytes(value)
+        timestamp = base64_encode(int_to_bytes(self.get_timestamp()))
+        sep = want_bytes(self.sep)
+        value = value + sep + timestamp
+        return value + sep + self.get_signature(value)
+
+    def unsign(self, value, max_age=None, return_timestamp=False):
+        """Works like the regular :meth:`.Signer.unsign` but can also
+        validate the time. See the base docstring of the class for
+        the general behavior. If ``return_timestamp`` is ``True`` the
+        timestamp of the signature will be returned as a naive
+        :class:`datetime.datetime` object in UTC.
+        """
+        try:
+            result = Signer.unsign(self, value)
+            sig_error = None
+        except BadSignature as e:
+            sig_error = e
+            result = e.payload or b""
+        sep = want_bytes(self.sep)
+
+        # If there is no timestamp in the result there is something
+        # seriously wrong. In case there was a signature error, we raise
+        # that one directly, otherwise we have a weird situation in
+        # which we shouldn't have come except someone uses a time-based
+        # serializer on non-timestamp data, so catch that.
+        if sep not in result:
+            if sig_error:
+                raise sig_error
+            raise BadTimeSignature("timestamp missing", payload=result)
+
+        value, timestamp = result.rsplit(sep, 1)
+        try:
+            timestamp = bytes_to_int(base64_decode(timestamp))
+        except Exception:
+            timestamp = None
+
+        # Signature is *not* okay. Raise a proper error now that we have
+        # split the value and the timestamp.
+        if sig_error is not None:
+            raise BadTimeSignature(
+                text_type(sig_error), payload=value, date_signed=timestamp
+            )
+
+        # Signature was okay but the timestamp is actually not there or
+        # malformed. Should not happen, but we handle it anyway.
+        if timestamp is None:
+            raise BadTimeSignature("Malformed timestamp", payload=value)
+
+        # Check timestamp is not older than max_age
+        if max_age is not None:
+            age = self.get_timestamp() - timestamp
+            if age > max_age:
+                raise SignatureExpired(
+                    "Signature age %s > %s seconds" % (age, max_age),
+                    payload=value,
+                    date_signed=self.timestamp_to_datetime(timestamp),
+                )
+
+        if return_timestamp:
+            return value, self.timestamp_to_datetime(timestamp)
+        return value
+
+    def validate(self, signed_value, max_age=None):
+        """Only validates the given signed value. Returns ``True`` if
+        the signature exists and is valid."""
+        try:
+            self.unsign(signed_value, max_age=max_age)
+            return True
+        except BadSignature:
+            return False
+
+
+class TimedSerializer(Serializer):
+    """Uses :class:`TimestampSigner` instead of the default
+    :class:`.Signer`.
+    """
+
+    default_signer = TimestampSigner
+
+    def loads(self, s, max_age=None, return_timestamp=False, salt=None):
+        """Reverse of :meth:`dumps`, raises :exc:`.BadSignature` if the
+        signature validation fails. If a ``max_age`` is provided it will
+        ensure the signature is not older than that time in seconds. In
+        case the signature is outdated, :exc:`.SignatureExpired` is
+        raised. All arguments are forwarded to the signer's
+        :meth:`~TimestampSigner.unsign` method.
+        """
+        s = want_bytes(s)
+        last_exception = None
+        for signer in self.iter_unsigners(salt):
+            try:
+                base64d, timestamp = signer.unsign(s, max_age, return_timestamp=True)
+                payload = self.load_payload(base64d)
+                if return_timestamp:
+                    return payload, timestamp
+                return payload
+            # If we get a signature expired it means we could read the
+            # signature but it's invalid.  In that case we do not want to
+            # try the next signer.
+            except SignatureExpired:
+                raise
+            except BadSignature as err:
+                last_exception = err
+        raise last_exception
+
+    def loads_unsafe(self, s, max_age=None, salt=None):
+        load_kwargs = {"max_age": max_age}
+        load_payload_kwargs = {}
+        return self._loads_unsafe_impl(s, salt, load_kwargs, load_payload_kwargs)
diff --git a/python/itsdangerous/url_safe.py b/python/itsdangerous/url_safe.py
new file mode 100644
index 0000000..fcaa011
--- /dev/null
+++ b/python/itsdangerous/url_safe.py
@@ -0,0 +1,65 @@
+import zlib
+
+from ._json import _CompactJSON
+from .encoding import base64_decode
+from .encoding import base64_encode
+from .exc import BadPayload
+from .serializer import Serializer
+from .timed import TimedSerializer
+
+
+class URLSafeSerializerMixin(object):
+    """Mixed in with a regular serializer it will attempt to zlib
+    compress the string to make it shorter if necessary. It will also
+    base64 encode the string so that it can safely be placed in a URL.
+    """
+
+    default_serializer = _CompactJSON
+
+    def load_payload(self, payload, *args, **kwargs):
+        decompress = False
+        if payload.startswith(b"."):
+            payload = payload[1:]
+            decompress = True
+        try:
+            json = base64_decode(payload)
+        except Exception as e:
+            raise BadPayload(
+                "Could not base64 decode the payload because of an exception",
+                original_error=e,
+            )
+        if decompress:
+            try:
+                json = zlib.decompress(json)
+            except Exception as e:
+                raise BadPayload(
+                    "Could not zlib decompress the payload before decoding the payload",
+                    original_error=e,
+                )
+        return super(URLSafeSerializerMixin, self).load_payload(json, *args, **kwargs)
+
+    def dump_payload(self, obj):
+        json = super(URLSafeSerializerMixin, self).dump_payload(obj)
+        is_compressed = False
+        compressed = zlib.compress(json)
+        if len(compressed) < (len(json) - 1):
+            json = compressed
+            is_compressed = True
+        base64d = base64_encode(json)
+        if is_compressed:
+            base64d = b"." + base64d
+        return base64d
+
+
+class URLSafeSerializer(URLSafeSerializerMixin, Serializer):
+    """Works like :class:`.Serializer` but dumps and loads into a URL
+    safe string consisting of the upper and lowercase character of the
+    alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
+    """
+
+
+class URLSafeTimedSerializer(URLSafeSerializerMixin, TimedSerializer):
+    """Works like :class:`.TimedSerializer` but dumps and loads into a
+    URL safe string consisting of the upper and lowercase character of
+    the alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
+    """
diff --git a/python/jinja2/__init__.py b/python/jinja2/__init__.py
new file mode 100644
index 0000000..15e13b6
--- /dev/null
+++ b/python/jinja2/__init__.py
@@ -0,0 +1,83 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2
+    ~~~~~~
+
+    Jinja2 is a template engine written in pure Python.  It provides a
+    Django inspired non-XML syntax but supports inline expressions and
+    an optional sandboxed environment.
+
+    Nutshell
+    --------
+
+    Here a small example of a Jinja2 template::
+
+        {% extends 'base.html' %}
+        {% block title %}Memberlist{% endblock %}
+        {% block content %}
+          <ul>
+          {% for user in users %}
+            <li><a href="{{ user.url }}">{{ user.username }}</a></li>
+          {% endfor %}
+          </ul>
+        {% endblock %}
+
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+__docformat__ = 'restructuredtext en'
+__version__ = '2.10.1'
+
+# high level interface
+from jinja2.environment import Environment, Template
+
+# loaders
+from jinja2.loaders import BaseLoader, FileSystemLoader, PackageLoader, \
+     DictLoader, FunctionLoader, PrefixLoader, ChoiceLoader, \
+     ModuleLoader
+
+# bytecode caches
+from jinja2.bccache import BytecodeCache, FileSystemBytecodeCache, \
+     MemcachedBytecodeCache
+
+# undefined types
+from jinja2.runtime import Undefined, DebugUndefined, StrictUndefined, \
+     make_logging_undefined
+
+# exceptions
+from jinja2.exceptions import TemplateError, UndefinedError, \
+     TemplateNotFound, TemplatesNotFound, TemplateSyntaxError, \
+     TemplateAssertionError, TemplateRuntimeError
+
+# decorators and public utilities
+from jinja2.filters import environmentfilter, contextfilter, \
+     evalcontextfilter
+from jinja2.utils import Markup, escape, clear_caches, \
+     environmentfunction, evalcontextfunction, contextfunction, \
+     is_undefined, select_autoescape
+
+__all__ = [
+    'Environment', 'Template', 'BaseLoader', 'FileSystemLoader',
+    'PackageLoader', 'DictLoader', 'FunctionLoader', 'PrefixLoader',
+    'ChoiceLoader', 'BytecodeCache', 'FileSystemBytecodeCache',
+    'MemcachedBytecodeCache', 'Undefined', 'DebugUndefined',
+    'StrictUndefined', 'TemplateError', 'UndefinedError', 'TemplateNotFound',
+    'TemplatesNotFound', 'TemplateSyntaxError', 'TemplateAssertionError',
+    'TemplateRuntimeError',
+    'ModuleLoader', 'environmentfilter', 'contextfilter', 'Markup', 'escape',
+    'environmentfunction', 'contextfunction', 'clear_caches', 'is_undefined',
+    'evalcontextfilter', 'evalcontextfunction', 'make_logging_undefined',
+    'select_autoescape',
+]
+
+
+def _patch_async():
+    from jinja2.utils import have_async_gen
+    if have_async_gen:
+        from jinja2.asyncsupport import patch_all
+        patch_all()
+
+
+_patch_async()
+del _patch_async
diff --git a/python/jinja2/_compat.py b/python/jinja2/_compat.py
new file mode 100644
index 0000000..61d8530
--- /dev/null
+++ b/python/jinja2/_compat.py
@@ -0,0 +1,99 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2._compat
+    ~~~~~~~~~~~~~~
+
+    Some py2/py3 compatibility support based on a stripped down
+    version of six so we don't have to depend on a specific version
+    of it.
+
+    :copyright: Copyright 2013 by the Jinja team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+import sys
+
+PY2 = sys.version_info[0] == 2
+PYPY = hasattr(sys, 'pypy_translation_info')
+_identity = lambda x: x
+
+
+if not PY2:
+    unichr = chr
+    range_type = range
+    text_type = str
+    string_types = (str,)
+    integer_types = (int,)
+
+    iterkeys = lambda d: iter(d.keys())
+    itervalues = lambda d: iter(d.values())
+    iteritems = lambda d: iter(d.items())
+
+    import pickle
+    from io import BytesIO, StringIO
+    NativeStringIO = StringIO
+
+    def reraise(tp, value, tb=None):
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+
+    ifilter = filter
+    imap = map
+    izip = zip
+    intern = sys.intern
+
+    implements_iterator = _identity
+    implements_to_string = _identity
+    encode_filename = _identity
+
+else:
+    unichr = unichr
+    text_type = unicode
+    range_type = xrange
+    string_types = (str, unicode)
+    integer_types = (int, long)
+
+    iterkeys = lambda d: d.iterkeys()
+    itervalues = lambda d: d.itervalues()
+    iteritems = lambda d: d.iteritems()
+
+    import cPickle as pickle
+    from cStringIO import StringIO as BytesIO, StringIO
+    NativeStringIO = BytesIO
+
+    exec('def reraise(tp, value, tb=None):\n raise tp, value, tb')
+
+    from itertools import imap, izip, ifilter
+    intern = intern
+
+    def implements_iterator(cls):
+        cls.next = cls.__next__
+        del cls.__next__
+        return cls
+
+    def implements_to_string(cls):
+        cls.__unicode__ = cls.__str__
+        cls.__str__ = lambda x: x.__unicode__().encode('utf-8')
+        return cls
+
+    def encode_filename(filename):
+        if isinstance(filename, unicode):
+            return filename.encode('utf-8')
+        return filename
+
+
+def with_metaclass(meta, *bases):
+    """Create a base class with a metaclass."""
+    # This requires a bit of explanation: the basic idea is to make a
+    # dummy metaclass for one level of class instantiation that replaces
+    # itself with the actual metaclass.
+    class metaclass(type):
+        def __new__(cls, name, this_bases, d):
+            return meta(name, bases, d)
+    return type.__new__(metaclass, 'temporary_class', (), {})
+
+
+try:
+    from urllib.parse import quote_from_bytes as url_quote
+except ImportError:
+    from urllib import quote as url_quote
diff --git a/python/jinja2/_identifier.py b/python/jinja2/_identifier.py
new file mode 100644
index 0000000..2eac35d
--- /dev/null
+++ b/python/jinja2/_identifier.py
@@ -0,0 +1,2 @@
+# generated by scripts/generate_identifier_pattern.py
+pattern = '·̀-ͯ·҃-֑҇-ׇֽֿׁׂׅׄؐ-ًؚ-ٰٟۖ-ۜ۟-۪ۤۧۨ-ܑۭܰ-݊ަ-ް߫-߳ࠖ-࠙ࠛ-ࠣࠥ-ࠧࠩ-࡙࠭-࡛ࣔ-ࣣ࣡-ःऺ-़ा-ॏ॑-ॗॢॣঁ-ঃ়া-ৄেৈো-্ৗৢৣਁ-ਃ਼ਾ-ੂੇੈੋ-੍ੑੰੱੵઁ-ઃ઼ા-ૅે-ૉો-્ૢૣଁ-ଃ଼ା-ୄେୈୋ-୍ୖୗୢୣஂா-ூெ-ைொ-்ௗఀ-ఃా-ౄె-ైొ-్ౕౖౢౣಁ-ಃ಼ಾ-ೄೆ-ೈೊ-್ೕೖೢೣഁ-ഃാ-ൄെ-ൈൊ-്ൗൢൣංඃ්ා-ුූෘ-ෟෲෳัิ-ฺ็-๎ັິ-ູົຼ່-ໍ༹༘༙༵༷༾༿ཱ-྄྆྇ྍ-ྗྙ-ྼ࿆ါ-ှၖ-ၙၞ-ၠၢ-ၤၧ-ၭၱ-ၴႂ-ႍႏႚ-ႝ፝-፟ᜒ-᜔ᜲ-᜴ᝒᝓᝲᝳ឴-៓៝᠋-᠍ᢅᢆᢩᤠ-ᤫᤰ-᤻ᨗ-ᨛᩕ-ᩞ᩠-᩿᩼᪰-᪽ᬀ-ᬄ᬴-᭄᭫-᭳ᮀ-ᮂᮡ-ᮭ᯦-᯳ᰤ-᰷᳐-᳔᳒-᳨᳭ᳲ-᳴᳸᳹᷀-᷵᷻-᷿‿⁀⁔⃐-⃥⃜⃡-⃰℘℮⳯-⵿⳱ⷠ-〪ⷿ-゙゚〯꙯ꙴ-꙽ꚞꚟ꛰꛱ꠂ꠆ꠋꠣ-ꠧꢀꢁꢴ-ꣅ꣠-꣱ꤦ-꤭ꥇ-꥓ꦀ-ꦃ꦳-꧀ꧥꨩ-ꨶꩃꩌꩍꩻ-ꩽꪰꪲ-ꪴꪷꪸꪾ꪿꫁ꫫ-ꫯꫵ꫶ꯣ-ꯪ꯬꯭ﬞ︀-️︠-︯︳︴﹍-﹏＿𐇽𐋠𐍶-𐍺𐨁-𐨃𐨅𐨆𐨌-𐨏𐨸-𐨿𐨺𐫦𐫥𑀀-𑀂𑀸-𑁆𑁿-𑂂𑂰-𑂺𑄀-𑄂𑄧-𑅳𑄴𑆀-𑆂𑆳-𑇊𑇀-𑇌𑈬-𑈷𑈾𑋟-𑋪𑌀-𑌃𑌼𑌾-𑍄𑍇𑍈𑍋-𑍍𑍗𑍢𑍣𑍦-𑍬𑍰-𑍴𑐵-𑑆𑒰-𑓃𑖯-𑖵𑖸-𑗀𑗜𑗝𑘰-𑙀𑚫-𑚷𑜝-𑜫𑰯-𑰶𑰸-𑰿𑲒-𑲧𑲩-𑲶𖫰-𖫴𖬰-𖬶𖽑-𖽾𖾏-𖾒𛲝𛲞𝅥-𝅩𝅭-𝅲𝅻-𝆂𝆅-𝆋𝆪-𝆭𝉂-𝉄𝨀-𝨶𝨻-𝩬𝩵𝪄𝪛-𝪟𝪡-𝪯𞀀-𞀆𞀈-𞀘𞀛-𞀡𞀣𞀤𞀦-𞣐𞀪-𞣖𞥄-𞥊󠄀-󠇯'
diff --git a/python/jinja2/asyncfilters.py b/python/jinja2/asyncfilters.py
new file mode 100644
index 0000000..5c1f46d
--- /dev/null
+++ b/python/jinja2/asyncfilters.py
@@ -0,0 +1,146 @@
+from functools import wraps
+
+from jinja2.asyncsupport import auto_aiter
+from jinja2 import filters
+
+
+async def auto_to_seq(value):
+    seq = []
+    if hasattr(value, '__aiter__'):
+        async for item in value:
+            seq.append(item)
+    else:
+        for item in value:
+            seq.append(item)
+    return seq
+
+
+async def async_select_or_reject(args, kwargs, modfunc, lookup_attr):
+    seq, func = filters.prepare_select_or_reject(
+        args, kwargs, modfunc, lookup_attr)
+    if seq:
+        async for item in auto_aiter(seq):
+            if func(item):
+                yield item
+
+
+def dualfilter(normal_filter, async_filter):
+    wrap_evalctx = False
+    if getattr(normal_filter, 'environmentfilter', False):
+        is_async = lambda args: args[0].is_async
+        wrap_evalctx = False
+    else:
+        if not getattr(normal_filter, 'evalcontextfilter', False) and \
+           not getattr(normal_filter, 'contextfilter', False):
+            wrap_evalctx = True
+        is_async = lambda args: args[0].environment.is_async
+
+    @wraps(normal_filter)
+    def wrapper(*args, **kwargs):
+        b = is_async(args)
+        if wrap_evalctx:
+            args = args[1:]
+        if b:
+            return async_filter(*args, **kwargs)
+        return normal_filter(*args, **kwargs)
+
+    if wrap_evalctx:
+        wrapper.evalcontextfilter = True
+
+    wrapper.asyncfiltervariant = True
+
+    return wrapper
+
+
+def asyncfiltervariant(original):
+    def decorator(f):
+        return dualfilter(original, f)
+    return decorator
+
+
+@asyncfiltervariant(filters.do_first)
+async def do_first(environment, seq):
+    try:
+        return await auto_aiter(seq).__anext__()
+    except StopAsyncIteration:
+        return environment.undefined('No first item, sequence was empty.')
+
+
+@asyncfiltervariant(filters.do_groupby)
+async def do_groupby(environment, value, attribute):
+    expr = filters.make_attrgetter(environment, attribute)
+    return [filters._GroupTuple(key, await auto_to_seq(values))
+            for key, values in filters.groupby(sorted(
+                await auto_to_seq(value), key=expr), expr)]
+
+
+@asyncfiltervariant(filters.do_join)
+async def do_join(eval_ctx, value, d=u'', attribute=None):
+    return filters.do_join(eval_ctx, await auto_to_seq(value), d, attribute)
+
+
+@asyncfiltervariant(filters.do_list)
+async def do_list(value):
+    return await auto_to_seq(value)
+
+
+@asyncfiltervariant(filters.do_reject)
+async def do_reject(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: not x, False)
+
+
+@asyncfiltervariant(filters.do_rejectattr)
+async def do_rejectattr(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: not x, True)
+
+
+@asyncfiltervariant(filters.do_select)
+async def do_select(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: x, False)
+
+
+@asyncfiltervariant(filters.do_selectattr)
+async def do_selectattr(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: x, True)
+
+
+@asyncfiltervariant(filters.do_map)
+async def do_map(*args, **kwargs):
+    seq, func = filters.prepare_map(args, kwargs)
+    if seq:
+        async for item in auto_aiter(seq):
+            yield func(item)
+
+
+@asyncfiltervariant(filters.do_sum)
+async def do_sum(environment, iterable, attribute=None, start=0):
+    rv = start
+    if attribute is not None:
+        func = filters.make_attrgetter(environment, attribute)
+    else:
+        func = lambda x: x
+    async for item in auto_aiter(iterable):
+        rv += func(item)
+    return rv
+
+
+@asyncfiltervariant(filters.do_slice)
+async def do_slice(value, slices, fill_with=None):
+    return filters.do_slice(await auto_to_seq(value), slices, fill_with)
+
+
+ASYNC_FILTERS = {
+    'first':        do_first,
+    'groupby':      do_groupby,
+    'join':         do_join,
+    'list':         do_list,
+    # we intentionally do not support do_last because that would be
+    # ridiculous
+    'reject':       do_reject,
+    'rejectattr':   do_rejectattr,
+    'map':          do_map,
+    'select':       do_select,
+    'selectattr':   do_selectattr,
+    'sum':          do_sum,
+    'slice':        do_slice,
+}
diff --git a/python/jinja2/asyncsupport.py b/python/jinja2/asyncsupport.py
new file mode 100644
index 0000000..b1e7b5c
--- /dev/null
+++ b/python/jinja2/asyncsupport.py
@@ -0,0 +1,256 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.asyncsupport
+    ~~~~~~~~~~~~~~~~~~~
+
+    Has all the code for async support which is implemented as a patch
+    for supported Python versions.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import sys
+import asyncio
+import inspect
+from functools import update_wrapper
+
+from jinja2.utils import concat, internalcode, Markup
+from jinja2.environment import TemplateModule
+from jinja2.runtime import LoopContextBase, _last_iteration
+
+
+async def concat_async(async_gen):
+    rv = []
+    async def collect():
+        async for event in async_gen:
+            rv.append(event)
+    await collect()
+    return concat(rv)
+
+
+async def generate_async(self, *args, **kwargs):
+    vars = dict(*args, **kwargs)
+    try:
+        async for event in self.root_render_func(self.new_context(vars)):
+            yield event
+    except Exception:
+        exc_info = sys.exc_info()
+    else:
+        return
+    yield self.environment.handle_exception(exc_info, True)
+
+
+def wrap_generate_func(original_generate):
+    def _convert_generator(self, loop, args, kwargs):
+        async_gen = self.generate_async(*args, **kwargs)
+        try:
+            while 1:
+                yield loop.run_until_complete(async_gen.__anext__())
+        except StopAsyncIteration:
+            pass
+    def generate(self, *args, **kwargs):
+        if not self.environment.is_async:
+            return original_generate(self, *args, **kwargs)
+        return _convert_generator(self, asyncio.get_event_loop(), args, kwargs)
+    return update_wrapper(generate, original_generate)
+
+
+async def render_async(self, *args, **kwargs):
+    if not self.environment.is_async:
+        raise RuntimeError('The environment was not created with async mode '
+                           'enabled.')
+
+    vars = dict(*args, **kwargs)
+    ctx = self.new_context(vars)
+
+    try:
+        return await concat_async(self.root_render_func(ctx))
+    except Exception:
+        exc_info = sys.exc_info()
+    return self.environment.handle_exception(exc_info, True)
+
+
+def wrap_render_func(original_render):
+    def render(self, *args, **kwargs):
+        if not self.environment.is_async:
+            return original_render(self, *args, **kwargs)
+        loop = asyncio.get_event_loop()
+        return loop.run_until_complete(self.render_async(*args, **kwargs))
+    return update_wrapper(render, original_render)
+
+
+def wrap_block_reference_call(original_call):
+    @internalcode
+    async def async_call(self):
+        rv = await concat_async(self._stack[self._depth](self._context))
+        if self._context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        return rv
+
+    @internalcode
+    def __call__(self):
+        if not self._context.environment.is_async:
+            return original_call(self)
+        return async_call(self)
+
+    return update_wrapper(__call__, original_call)
+
+
+def wrap_macro_invoke(original_invoke):
+    @internalcode
+    async def async_invoke(self, arguments, autoescape):
+        rv = await self._func(*arguments)
+        if autoescape:
+            rv = Markup(rv)
+        return rv
+
+    @internalcode
+    def _invoke(self, arguments, autoescape):
+        if not self._environment.is_async:
+            return original_invoke(self, arguments, autoescape)
+        return async_invoke(self, arguments, autoescape)
+    return update_wrapper(_invoke, original_invoke)
+
+
+@internalcode
+async def get_default_module_async(self):
+    if self._module is not None:
+        return self._module
+    self._module = rv = await self.make_module_async()
+    return rv
+
+
+def wrap_default_module(original_default_module):
+    @internalcode
+    def _get_default_module(self):
+        if self.environment.is_async:
+            raise RuntimeError('Template module attribute is unavailable '
+                               'in async mode')
+        return original_default_module(self)
+    return _get_default_module
+
+
+async def make_module_async(self, vars=None, shared=False, locals=None):
+    context = self.new_context(vars, shared, locals)
+    body_stream = []
+    async for item in self.root_render_func(context):
+        body_stream.append(item)
+    return TemplateModule(self, context, body_stream)
+
+
+def patch_template():
+    from jinja2 import Template
+    Template.generate = wrap_generate_func(Template.generate)
+    Template.generate_async = update_wrapper(
+        generate_async, Template.generate_async)
+    Template.render_async = update_wrapper(
+        render_async, Template.render_async)
+    Template.render = wrap_render_func(Template.render)
+    Template._get_default_module = wrap_default_module(
+        Template._get_default_module)
+    Template._get_default_module_async = get_default_module_async
+    Template.make_module_async = update_wrapper(
+        make_module_async, Template.make_module_async)
+
+
+def patch_runtime():
+    from jinja2.runtime import BlockReference, Macro
+    BlockReference.__call__ = wrap_block_reference_call(
+        BlockReference.__call__)
+    Macro._invoke = wrap_macro_invoke(Macro._invoke)
+
+
+def patch_filters():
+    from jinja2.filters import FILTERS
+    from jinja2.asyncfilters import ASYNC_FILTERS
+    FILTERS.update(ASYNC_FILTERS)
+
+
+def patch_all():
+    patch_template()
+    patch_runtime()
+    patch_filters()
+
+
+async def auto_await(value):
+    if inspect.isawaitable(value):
+        return await value
+    return value
+
+
+async def auto_aiter(iterable):
+    if hasattr(iterable, '__aiter__'):
+        async for item in iterable:
+            yield item
+        return
+    for item in iterable:
+        yield item
+
+
+class AsyncLoopContext(LoopContextBase):
+
+    def __init__(self, async_iterator, undefined, after, length, recurse=None,
+                 depth0=0):
+        LoopContextBase.__init__(self, undefined, recurse, depth0)
+        self._async_iterator = async_iterator
+        self._after = after
+        self._length = length
+
+    @property
+    def length(self):
+        if self._length is None:
+            raise TypeError('Loop length for some iterators cannot be '
+                            'lazily calculated in async mode')
+        return self._length
+
+    def __aiter__(self):
+        return AsyncLoopContextIterator(self)
+
+
+class AsyncLoopContextIterator(object):
+    __slots__ = ('context',)
+
+    def __init__(self, context):
+        self.context = context
+
+    def __aiter__(self):
+        return self
+
+    async def __anext__(self):
+        ctx = self.context
+        ctx.index0 += 1
+        if ctx._after is _last_iteration:
+            raise StopAsyncIteration()
+        ctx._before = ctx._current
+        ctx._current = ctx._after
+        try:
+            ctx._after = await ctx._async_iterator.__anext__()
+        except StopAsyncIteration:
+            ctx._after = _last_iteration
+        return ctx._current, ctx
+
+
+async def make_async_loop_context(iterable, undefined, recurse=None, depth0=0):
+    # Length is more complicated and less efficient in async mode.  The
+    # reason for this is that we cannot know if length will be used
+    # upfront but because length is a property we cannot lazily execute it
+    # later.  This means that we need to buffer it up and measure :(
+    #
+    # We however only do this for actual iterators, not for async
+    # iterators as blocking here does not seem like the best idea in the
+    # world.
+    try:
+        length = len(iterable)
+    except (TypeError, AttributeError):
+        if not hasattr(iterable, '__aiter__'):
+            iterable = tuple(iterable)
+            length = len(iterable)
+        else:
+            length = None
+    async_iterator = auto_aiter(iterable)
+    try:
+        after = await async_iterator.__anext__()
+    except StopAsyncIteration:
+        after = _last_iteration
+    return AsyncLoopContext(async_iterator, undefined, after, length, recurse,
+                            depth0)
diff --git a/python/jinja2/bccache.py b/python/jinja2/bccache.py
new file mode 100644
index 0000000..080e527
--- /dev/null
+++ b/python/jinja2/bccache.py
@@ -0,0 +1,362 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.bccache
+    ~~~~~~~~~~~~~~
+
+    This module implements the bytecode cache system Jinja is optionally
+    using.  This is useful if you have very complex template situations and
+    the compiliation of all those templates slow down your application too
+    much.
+
+    Situations where this is useful are often forking web applications that
+    are initialized on the first request.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+from os import path, listdir
+import os
+import sys
+import stat
+import errno
+import marshal
+import tempfile
+import fnmatch
+from hashlib import sha1
+from jinja2.utils import open_if_exists
+from jinja2._compat import BytesIO, pickle, PY2, text_type
+
+
+# marshal works better on 3.x, one hack less required
+if not PY2:
+    marshal_dump = marshal.dump
+    marshal_load = marshal.load
+else:
+
+    def marshal_dump(code, f):
+        if isinstance(f, file):
+            marshal.dump(code, f)
+        else:
+            f.write(marshal.dumps(code))
+
+    def marshal_load(f):
+        if isinstance(f, file):
+            return marshal.load(f)
+        return marshal.loads(f.read())
+
+
+bc_version = 3
+
+# magic version used to only change with new jinja versions.  With 2.6
+# we change this to also take Python version changes into account.  The
+# reason for this is that Python tends to segfault if fed earlier bytecode
+# versions because someone thought it would be a good idea to reuse opcodes
+# or make Python incompatible with earlier versions.
+bc_magic = 'j2'.encode('ascii') + \
+    pickle.dumps(bc_version, 2) + \
+    pickle.dumps((sys.version_info[0] << 24) | sys.version_info[1])
+
+
+class Bucket(object):
+    """Buckets are used to store the bytecode for one template.  It's created
+    and initialized by the bytecode cache and passed to the loading functions.
+
+    The buckets get an internal checksum from the cache assigned and use this
+    to automatically reject outdated cache material.  Individual bytecode
+    cache subclasses don't have to care about cache invalidation.
+    """
+
+    def __init__(self, environment, key, checksum):
+        self.environment = environment
+        self.key = key
+        self.checksum = checksum
+        self.reset()
+
+    def reset(self):
+        """Resets the bucket (unloads the bytecode)."""
+        self.code = None
+
+    def load_bytecode(self, f):
+        """Loads bytecode from a file or file like object."""
+        # make sure the magic header is correct
+        magic = f.read(len(bc_magic))
+        if magic != bc_magic:
+            self.reset()
+            return
+        # the source code of the file changed, we need to reload
+        checksum = pickle.load(f)
+        if self.checksum != checksum:
+            self.reset()
+            return
+        # if marshal_load fails then we need to reload
+        try:
+            self.code = marshal_load(f)
+        except (EOFError, ValueError, TypeError):
+            self.reset()
+            return
+
+    def write_bytecode(self, f):
+        """Dump the bytecode into the file or file like object passed."""
+        if self.code is None:
+            raise TypeError('can\'t write empty bucket')
+        f.write(bc_magic)
+        pickle.dump(self.checksum, f, 2)
+        marshal_dump(self.code, f)
+
+    def bytecode_from_string(self, string):
+        """Load bytecode from a string."""
+        self.load_bytecode(BytesIO(string))
+
+    def bytecode_to_string(self):
+        """Return the bytecode as string."""
+        out = BytesIO()
+        self.write_bytecode(out)
+        return out.getvalue()
+
+
+class BytecodeCache(object):
+    """To implement your own bytecode cache you have to subclass this class
+    and override :meth:`load_bytecode` and :meth:`dump_bytecode`.  Both of
+    these methods are passed a :class:`~jinja2.bccache.Bucket`.
+
+    A very basic bytecode cache that saves the bytecode on the file system::
+
+        from os import path
+
+        class MyCache(BytecodeCache):
+
+            def __init__(self, directory):
+                self.directory = directory
+
+            def load_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                if path.exists(filename):
+                    with open(filename, 'rb') as f:
+                        bucket.load_bytecode(f)
+
+            def dump_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                with open(filename, 'wb') as f:
+                    bucket.write_bytecode(f)
+
+    A more advanced version of a filesystem based bytecode cache is part of
+    Jinja2.
+    """
+
+    def load_bytecode(self, bucket):
+        """Subclasses have to override this method to load bytecode into a
+        bucket.  If they are not able to find code in the cache for the
+        bucket, it must not do anything.
+        """
+        raise NotImplementedError()
+
+    def dump_bytecode(self, bucket):
+        """Subclasses have to override this method to write the bytecode
+        from a bucket back to the cache.  If it unable to do so it must not
+        fail silently but raise an exception.
+        """
+        raise NotImplementedError()
+
+    def clear(self):
+        """Clears the cache.  This method is not used by Jinja2 but should be
+        implemented to allow applications to clear the bytecode cache used
+        by a particular environment.
+        """
+
+    def get_cache_key(self, name, filename=None):
+        """Returns the unique hash key for this template name."""
+        hash = sha1(name.encode('utf-8'))
+        if filename is not None:
+            filename = '|' + filename
+            if isinstance(filename, text_type):
+                filename = filename.encode('utf-8')
+            hash.update(filename)
+        return hash.hexdigest()
+
+    def get_source_checksum(self, source):
+        """Returns a checksum for the source."""
+        return sha1(source.encode('utf-8')).hexdigest()
+
+    def get_bucket(self, environment, name, filename, source):
+        """Return a cache bucket for the given template.  All arguments are
+        mandatory but filename may be `None`.
+        """
+        key = self.get_cache_key(name, filename)
+        checksum = self.get_source_checksum(source)
+        bucket = Bucket(environment, key, checksum)
+        self.load_bytecode(bucket)
+        return bucket
+
+    def set_bucket(self, bucket):
+        """Put the bucket into the cache."""
+        self.dump_bytecode(bucket)
+
+
+class FileSystemBytecodeCache(BytecodeCache):
+    """A bytecode cache that stores bytecode on the filesystem.  It accepts
+    two arguments: The directory where the cache items are stored and a
+    pattern string that is used to build the filename.
+
+    If no directory is specified a default cache directory is selected.  On
+    Windows the user's temp directory is used, on UNIX systems a directory
+    is created for the user in the system temp directory.
+
+    The pattern can be used to have multiple separate caches operate on the
+    same directory.  The default pattern is ``'__jinja2_%s.cache'``.  ``%s``
+    is replaced with the cache key.
+
+    >>> bcc = FileSystemBytecodeCache('/tmp/jinja_cache', '%s.cache')
+
+    This bytecode cache supports clearing of the cache using the clear method.
+    """
+
+    def __init__(self, directory=None, pattern='__jinja2_%s.cache'):
+        if directory is None:
+            directory = self._get_default_cache_dir()
+        self.directory = directory
+        self.pattern = pattern
+
+    def _get_default_cache_dir(self):
+        def _unsafe_dir():
+            raise RuntimeError('Cannot determine safe temp directory.  You '
+                               'need to explicitly provide one.')
+
+        tmpdir = tempfile.gettempdir()
+
+        # On windows the temporary directory is used specific unless
+        # explicitly forced otherwise.  We can just use that.
+        if os.name == 'nt':
+            return tmpdir
+        if not hasattr(os, 'getuid'):
+            _unsafe_dir()
+
+        dirname = '_jinja2-cache-%d' % os.getuid()
+        actual_dir = os.path.join(tmpdir, dirname)
+
+        try:
+            os.mkdir(actual_dir, stat.S_IRWXU)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+        try:
+            os.chmod(actual_dir, stat.S_IRWXU)
+            actual_dir_stat = os.lstat(actual_dir)
+            if actual_dir_stat.st_uid != os.getuid() \
+               or not stat.S_ISDIR(actual_dir_stat.st_mode) \
+               or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU:
+                _unsafe_dir()
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        actual_dir_stat = os.lstat(actual_dir)
+        if actual_dir_stat.st_uid != os.getuid() \
+           or not stat.S_ISDIR(actual_dir_stat.st_mode) \
+           or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU:
+            _unsafe_dir()
+
+        return actual_dir
+
+    def _get_cache_filename(self, bucket):
+        return path.join(self.directory, self.pattern % bucket.key)
+
+    def load_bytecode(self, bucket):
+        f = open_if_exists(self._get_cache_filename(bucket), 'rb')
+        if f is not None:
+            try:
+                bucket.load_bytecode(f)
+            finally:
+                f.close()
+
+    def dump_bytecode(self, bucket):
+        f = open(self._get_cache_filename(bucket), 'wb')
+        try:
+            bucket.write_bytecode(f)
+        finally:
+            f.close()
+
+    def clear(self):
+        # imported lazily here because google app-engine doesn't support
+        # write access on the file system and the function does not exist
+        # normally.
+        from os import remove
+        files = fnmatch.filter(listdir(self.directory), self.pattern % '*')
+        for filename in files:
+            try:
+                remove(path.join(self.directory, filename))
+            except OSError:
+                pass
+
+
+class MemcachedBytecodeCache(BytecodeCache):
+    """This class implements a bytecode cache that uses a memcache cache for
+    storing the information.  It does not enforce a specific memcache library
+    (tummy's memcache or cmemcache) but will accept any class that provides
+    the minimal interface required.
+
+    Libraries compatible with this class:
+
+    -   `werkzeug <http://werkzeug.pocoo.org/>`_.contrib.cache
+    -   `python-memcached <https://www.tummy.com/Community/software/python-memcached/>`_
+    -   `cmemcache <http://gijsbert.org/cmemcache/>`_
+
+    (Unfortunately the django cache interface is not compatible because it
+    does not support storing binary data, only unicode.  You can however pass
+    the underlying cache client to the bytecode cache which is available
+    as `django.core.cache.cache._client`.)
+
+    The minimal interface for the client passed to the constructor is this:
+
+    .. class:: MinimalClientInterface
+
+        .. method:: set(key, value[, timeout])
+
+            Stores the bytecode in the cache.  `value` is a string and
+            `timeout` the timeout of the key.  If timeout is not provided
+            a default timeout or no timeout should be assumed, if it's
+            provided it's an integer with the number of seconds the cache
+            item should exist.
+
+        .. method:: get(key)
+
+            Returns the value for the cache key.  If the item does not
+            exist in the cache the return value must be `None`.
+
+    The other arguments to the constructor are the prefix for all keys that
+    is added before the actual cache key and the timeout for the bytecode in
+    the cache system.  We recommend a high (or no) timeout.
+
+    This bytecode cache does not support clearing of used items in the cache.
+    The clear method is a no-operation function.
+
+    .. versionadded:: 2.7
+       Added support for ignoring memcache errors through the
+       `ignore_memcache_errors` parameter.
+    """
+
+    def __init__(self, client, prefix='jinja2/bytecode/', timeout=None,
+                 ignore_memcache_errors=True):
+        self.client = client
+        self.prefix = prefix
+        self.timeout = timeout
+        self.ignore_memcache_errors = ignore_memcache_errors
+
+    def load_bytecode(self, bucket):
+        try:
+            code = self.client.get(self.prefix + bucket.key)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
+            code = None
+        if code is not None:
+            bucket.bytecode_from_string(code)
+
+    def dump_bytecode(self, bucket):
+        args = (self.prefix + bucket.key, bucket.bytecode_to_string())
+        if self.timeout is not None:
+            args += (self.timeout,)
+        try:
+            self.client.set(*args)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
diff --git a/python/jinja2/compiler.py b/python/jinja2/compiler.py
new file mode 100644
index 0000000..d534a82
--- /dev/null
+++ b/python/jinja2/compiler.py
@@ -0,0 +1,1721 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.compiler
+    ~~~~~~~~~~~~~~~
+
+    Compiles nodes into python code.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+from itertools import chain
+from copy import deepcopy
+from keyword import iskeyword as is_python_keyword
+from functools import update_wrapper
+from jinja2 import nodes
+from jinja2.nodes import EvalContext
+from jinja2.visitor import NodeVisitor
+from jinja2.optimizer import Optimizer
+from jinja2.exceptions import TemplateAssertionError
+from jinja2.utils import Markup, concat, escape
+from jinja2._compat import range_type, text_type, string_types, \
+     iteritems, NativeStringIO, imap, izip
+from jinja2.idtracking import Symbols, VAR_LOAD_PARAMETER, \
+     VAR_LOAD_RESOLVE, VAR_LOAD_ALIAS, VAR_LOAD_UNDEFINED
+
+
+operators = {
+    'eq':       '==',
+    'ne':       '!=',
+    'gt':       '>',
+    'gteq':     '>=',
+    'lt':       '<',
+    'lteq':     '<=',
+    'in':       'in',
+    'notin':    'not in'
+}
+
+# what method to iterate over items do we want to use for dict iteration
+# in generated code?  on 2.x let's go with iteritems, on 3.x with items
+if hasattr(dict, 'iteritems'):
+    dict_item_iter = 'iteritems'
+else:
+    dict_item_iter = 'items'
+
+code_features = ['division']
+
+# does this python version support generator stops? (PEP 0479)
+try:
+    exec('from __future__ import generator_stop')
+    code_features.append('generator_stop')
+except SyntaxError:
+    pass
+
+# does this python version support yield from?
+try:
+    exec('def f(): yield from x()')
+except SyntaxError:
+    supports_yield_from = False
+else:
+    supports_yield_from = True
+
+
+def optimizeconst(f):
+    def new_func(self, node, frame, **kwargs):
+        # Only optimize if the frame is not volatile
+        if self.optimized and not frame.eval_ctx.volatile:
+            new_node = self.optimizer.visit(node, frame.eval_ctx)
+            if new_node != node:
+                return self.visit(new_node, frame)
+        return f(self, node, frame, **kwargs)
+    return update_wrapper(new_func, f)
+
+
+def generate(node, environment, name, filename, stream=None,
+             defer_init=False, optimized=True):
+    """Generate the python source for a node tree."""
+    if not isinstance(node, nodes.Template):
+        raise TypeError('Can\'t compile non template nodes')
+    generator = environment.code_generator_class(environment, name, filename,
+                                                 stream, defer_init,
+                                                 optimized)
+    generator.visit(node)
+    if stream is None:
+        return generator.stream.getvalue()
+
+
+def has_safe_repr(value):
+    """Does the node have a safe representation?"""
+    if value is None or value is NotImplemented or value is Ellipsis:
+        return True
+    if type(value) in (bool, int, float, complex, range_type, Markup) + string_types:
+        return True
+    if type(value) in (tuple, list, set, frozenset):
+        for item in value:
+            if not has_safe_repr(item):
+                return False
+        return True
+    elif type(value) is dict:
+        for key, value in iteritems(value):
+            if not has_safe_repr(key):
+                return False
+            if not has_safe_repr(value):
+                return False
+        return True
+    return False
+
+
+def find_undeclared(nodes, names):
+    """Check if the names passed are accessed undeclared.  The return value
+    is a set of all the undeclared names from the sequence of names found.
+    """
+    visitor = UndeclaredNameVisitor(names)
+    try:
+        for node in nodes:
+            visitor.visit(node)
+    except VisitorExit:
+        pass
+    return visitor.undeclared
+
+
+class MacroRef(object):
+
+    def __init__(self, node):
+        self.node = node
+        self.accesses_caller = False
+        self.accesses_kwargs = False
+        self.accesses_varargs = False
+
+
+class Frame(object):
+    """Holds compile time information for us."""
+
+    def __init__(self, eval_ctx, parent=None, level=None):
+        self.eval_ctx = eval_ctx
+        self.symbols = Symbols(parent and parent.symbols or None,
+                               level=level)
+
+        # a toplevel frame is the root + soft frames such as if conditions.
+        self.toplevel = False
+
+        # the root frame is basically just the outermost frame, so no if
+        # conditions.  This information is used to optimize inheritance
+        # situations.
+        self.rootlevel = False
+
+        # in some dynamic inheritance situations the compiler needs to add
+        # write tests around output statements.
+        self.require_output_check = parent and parent.require_output_check
+
+        # inside some tags we are using a buffer rather than yield statements.
+        # this for example affects {% filter %} or {% macro %}.  If a frame
+        # is buffered this variable points to the name of the list used as
+        # buffer.
+        self.buffer = None
+
+        # the name of the block we're in, otherwise None.
+        self.block = parent and parent.block or None
+
+        # the parent of this frame
+        self.parent = parent
+
+        if parent is not None:
+            self.buffer = parent.buffer
+
+    def copy(self):
+        """Create a copy of the current one."""
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.symbols = self.symbols.copy()
+        return rv
+
+    def inner(self, isolated=False):
+        """Return an inner frame."""
+        if isolated:
+            return Frame(self.eval_ctx, level=self.symbols.level + 1)
+        return Frame(self.eval_ctx, self)
+
+    def soft(self):
+        """Return a soft frame.  A soft frame may not be modified as
+        standalone thing as it shares the resources with the frame it
+        was created of, but it's not a rootlevel frame any longer.
+
+        This is only used to implement if-statements.
+        """
+        rv = self.copy()
+        rv.rootlevel = False
+        return rv
+
+    __copy__ = copy
+
+
+class VisitorExit(RuntimeError):
+    """Exception used by the `UndeclaredNameVisitor` to signal a stop."""
+
+
+class DependencyFinderVisitor(NodeVisitor):
+    """A visitor that collects filter and test calls."""
+
+    def __init__(self):
+        self.filters = set()
+        self.tests = set()
+
+    def visit_Filter(self, node):
+        self.generic_visit(node)
+        self.filters.add(node.name)
+
+    def visit_Test(self, node):
+        self.generic_visit(node)
+        self.tests.add(node.name)
+
+    def visit_Block(self, node):
+        """Stop visiting at blocks."""
+
+
+class UndeclaredNameVisitor(NodeVisitor):
+    """A visitor that checks if a name is accessed without being
+    declared.  This is different from the frame visitor as it will
+    not stop at closure frames.
+    """
+
+    def __init__(self, names):
+        self.names = set(names)
+        self.undeclared = set()
+
+    def visit_Name(self, node):
+        if node.ctx == 'load' and node.name in self.names:
+            self.undeclared.add(node.name)
+            if self.undeclared == self.names:
+                raise VisitorExit()
+        else:
+            self.names.discard(node.name)
+
+    def visit_Block(self, node):
+        """Stop visiting a blocks."""
+
+
+class CompilerExit(Exception):
+    """Raised if the compiler encountered a situation where it just
+    doesn't make sense to further process the code.  Any block that
+    raises such an exception is not further processed.
+    """
+
+
+class CodeGenerator(NodeVisitor):
+
+    def __init__(self, environment, name, filename, stream=None,
+                 defer_init=False, optimized=True):
+        if stream is None:
+            stream = NativeStringIO()
+        self.environment = environment
+        self.name = name
+        self.filename = filename
+        self.stream = stream
+        self.created_block_context = False
+        self.defer_init = defer_init
+        self.optimized = optimized
+        if optimized:
+            self.optimizer = Optimizer(environment)
+
+        # aliases for imports
+        self.import_aliases = {}
+
+        # a registry for all blocks.  Because blocks are moved out
+        # into the global python scope they are registered here
+        self.blocks = {}
+
+        # the number of extends statements so far
+        self.extends_so_far = 0
+
+        # some templates have a rootlevel extends.  In this case we
+        # can safely assume that we're a child template and do some
+        # more optimizations.
+        self.has_known_extends = False
+
+        # the current line number
+        self.code_lineno = 1
+
+        # registry of all filters and tests (global, not block local)
+        self.tests = {}
+        self.filters = {}
+
+        # the debug information
+        self.debug_info = []
+        self._write_debug_info = None
+
+        # the number of new lines before the next write()
+        self._new_lines = 0
+
+        # the line number of the last written statement
+        self._last_line = 0
+
+        # true if nothing was written so far.
+        self._first_write = True
+
+        # used by the `temporary_identifier` method to get new
+        # unique, temporary identifier
+        self._last_identifier = 0
+
+        # the current indentation
+        self._indentation = 0
+
+        # Tracks toplevel assignments
+        self._assign_stack = []
+
+        # Tracks parameter definition blocks
+        self._param_def_block = []
+
+        # Tracks the current context.
+        self._context_reference_stack = ['context']
+
+    # -- Various compilation helpers
+
+    def fail(self, msg, lineno):
+        """Fail with a :exc:`TemplateAssertionError`."""
+        raise TemplateAssertionError(msg, lineno, self.name, self.filename)
+
+    def temporary_identifier(self):
+        """Get a new unique identifier."""
+        self._last_identifier += 1
+        return 't_%d' % self._last_identifier
+
+    def buffer(self, frame):
+        """Enable buffering for the frame from that point onwards."""
+        frame.buffer = self.temporary_identifier()
+        self.writeline('%s = []' % frame.buffer)
+
+    def return_buffer_contents(self, frame, force_unescaped=False):
+        """Return the buffer contents of the frame."""
+        if not force_unescaped:
+            if frame.eval_ctx.volatile:
+                self.writeline('if context.eval_ctx.autoescape:')
+                self.indent()
+                self.writeline('return Markup(concat(%s))' % frame.buffer)
+                self.outdent()
+                self.writeline('else:')
+                self.indent()
+                self.writeline('return concat(%s)' % frame.buffer)
+                self.outdent()
+                return
+            elif frame.eval_ctx.autoescape:
+                self.writeline('return Markup(concat(%s))' % frame.buffer)
+                return
+        self.writeline('return concat(%s)' % frame.buffer)
+
+    def indent(self):
+        """Indent by one."""
+        self._indentation += 1
+
+    def outdent(self, step=1):
+        """Outdent by step."""
+        self._indentation -= step
+
+    def start_write(self, frame, node=None):
+        """Yield or write into the frame buffer."""
+        if frame.buffer is None:
+            self.writeline('yield ', node)
+        else:
+            self.writeline('%s.append(' % frame.buffer, node)
+
+    def end_write(self, frame):
+        """End the writing process started by `start_write`."""
+        if frame.buffer is not None:
+            self.write(')')
+
+    def simple_write(self, s, frame, node=None):
+        """Simple shortcut for start_write + write + end_write."""
+        self.start_write(frame, node)
+        self.write(s)
+        self.end_write(frame)
+
+    def blockvisit(self, nodes, frame):
+        """Visit a list of nodes as block in a frame.  If the current frame
+        is no buffer a dummy ``if 0: yield None`` is written automatically.
+        """
+        try:
+            self.writeline('pass')
+            for node in nodes:
+                self.visit(node, frame)
+        except CompilerExit:
+            pass
+
+    def write(self, x):
+        """Write a string into the output stream."""
+        if self._new_lines:
+            if not self._first_write:
+                self.stream.write('\n' * self._new_lines)
+                self.code_lineno += self._new_lines
+                if self._write_debug_info is not None:
+                    self.debug_info.append((self._write_debug_info,
+                                            self.code_lineno))
+                    self._write_debug_info = None
+            self._first_write = False
+            self.stream.write('    ' * self._indentation)
+            self._new_lines = 0
+        self.stream.write(x)
+
+    def writeline(self, x, node=None, extra=0):
+        """Combination of newline and write."""
+        self.newline(node, extra)
+        self.write(x)
+
+    def newline(self, node=None, extra=0):
+        """Add one or more newlines before the next write."""
+        self._new_lines = max(self._new_lines, 1 + extra)
+        if node is not None and node.lineno != self._last_line:
+            self._write_debug_info = node.lineno
+            self._last_line = node.lineno
+
+    def signature(self, node, frame, extra_kwargs=None):
+        """Writes a function call to the stream for the current node.
+        A leading comma is added automatically.  The extra keyword
+        arguments may not include python keywords otherwise a syntax
+        error could occour.  The extra keyword arguments should be given
+        as python dict.
+        """
+        # if any of the given keyword arguments is a python keyword
+        # we have to make sure that no invalid call is created.
+        kwarg_workaround = False
+        for kwarg in chain((x.key for x in node.kwargs), extra_kwargs or ()):
+            if is_python_keyword(kwarg):
+                kwarg_workaround = True
+                break
+
+        for arg in node.args:
+            self.write(', ')
+            self.visit(arg, frame)
+
+        if not kwarg_workaround:
+            for kwarg in node.kwargs:
+                self.write(', ')
+                self.visit(kwarg, frame)
+            if extra_kwargs is not None:
+                for key, value in iteritems(extra_kwargs):
+                    self.write(', %s=%s' % (key, value))
+        if node.dyn_args:
+            self.write(', *')
+            self.visit(node.dyn_args, frame)
+
+        if kwarg_workaround:
+            if node.dyn_kwargs is not None:
+                self.write(', **dict({')
+            else:
+                self.write(', **{')
+            for kwarg in node.kwargs:
+                self.write('%r: ' % kwarg.key)
+                self.visit(kwarg.value, frame)
+                self.write(', ')
+            if extra_kwargs is not None:
+                for key, value in iteritems(extra_kwargs):
+                    self.write('%r: %s, ' % (key, value))
+            if node.dyn_kwargs is not None:
+                self.write('}, **')
+                self.visit(node.dyn_kwargs, frame)
+                self.write(')')
+            else:
+                self.write('}')
+
+        elif node.dyn_kwargs is not None:
+            self.write(', **')
+            self.visit(node.dyn_kwargs, frame)
+
+    def pull_dependencies(self, nodes):
+        """Pull all the dependencies."""
+        visitor = DependencyFinderVisitor()
+        for node in nodes:
+            visitor.visit(node)
+        for dependency in 'filters', 'tests':
+            mapping = getattr(self, dependency)
+            for name in getattr(visitor, dependency):
+                if name not in mapping:
+                    mapping[name] = self.temporary_identifier()
+                self.writeline('%s = environment.%s[%r]' %
+                               (mapping[name], dependency, name))
+
+    def enter_frame(self, frame):
+        undefs = []
+        for target, (action, param) in iteritems(frame.symbols.loads):
+            if action == VAR_LOAD_PARAMETER:
+                pass
+            elif action == VAR_LOAD_RESOLVE:
+                self.writeline('%s = %s(%r)' %
+                               (target, self.get_resolve_func(), param))
+            elif action == VAR_LOAD_ALIAS:
+                self.writeline('%s = %s' % (target, param))
+            elif action == VAR_LOAD_UNDEFINED:
+                undefs.append(target)
+            else:
+                raise NotImplementedError('unknown load instruction')
+        if undefs:
+            self.writeline('%s = missing' % ' = '.join(undefs))
+
+    def leave_frame(self, frame, with_python_scope=False):
+        if not with_python_scope:
+            undefs = []
+            for target, _ in iteritems(frame.symbols.loads):
+                undefs.append(target)
+            if undefs:
+                self.writeline('%s = missing' % ' = '.join(undefs))
+
+    def func(self, name):
+        if self.environment.is_async:
+            return 'async def %s' % name
+        return 'def %s' % name
+
+    def macro_body(self, node, frame):
+        """Dump the function def of a macro or call block."""
+        frame = frame.inner()
+        frame.symbols.analyze_node(node)
+        macro_ref = MacroRef(node)
+
+        explicit_caller = None
+        skip_special_params = set()
+        args = []
+        for idx, arg in enumerate(node.args):
+            if arg.name == 'caller':
+                explicit_caller = idx
+            if arg.name in ('kwargs', 'varargs'):
+                skip_special_params.add(arg.name)
+            args.append(frame.symbols.ref(arg.name))
+
+        undeclared = find_undeclared(node.body, ('caller', 'kwargs', 'varargs'))
+
+        if 'caller' in undeclared:
+            # In older Jinja2 versions there was a bug that allowed caller
+            # to retain the special behavior even if it was mentioned in
+            # the argument list.  However thankfully this was only really
+            # working if it was the last argument.  So we are explicitly
+            # checking this now and error out if it is anywhere else in
+            # the argument list.
+            if explicit_caller is not None:
+                try:
+                    node.defaults[explicit_caller - len(node.args)]
+                except IndexError:
+                    self.fail('When defining macros or call blocks the '
+                              'special "caller" argument must be omitted '
+                              'or be given a default.', node.lineno)
+            else:
+                args.append(frame.symbols.declare_parameter('caller'))
+            macro_ref.accesses_caller = True
+        if 'kwargs' in undeclared and not 'kwargs' in skip_special_params:
+            args.append(frame.symbols.declare_parameter('kwargs'))
+            macro_ref.accesses_kwargs = True
+        if 'varargs' in undeclared and not 'varargs' in skip_special_params:
+            args.append(frame.symbols.declare_parameter('varargs'))
+            macro_ref.accesses_varargs = True
+
+        # macros are delayed, they never require output checks
+        frame.require_output_check = False
+        frame.symbols.analyze_node(node)
+        self.writeline('%s(%s):' % (self.func('macro'), ', '.join(args)), node)
+        self.indent()
+
+        self.buffer(frame)
+        self.enter_frame(frame)
+
+        self.push_parameter_definitions(frame)
+        for idx, arg in enumerate(node.args):
+            ref = frame.symbols.ref(arg.name)
+            self.writeline('if %s is missing:' % ref)
+            self.indent()
+            try:
+                default = node.defaults[idx - len(node.args)]
+            except IndexError:
+                self.writeline('%s = undefined(%r, name=%r)' % (
+                    ref,
+                    'parameter %r was not provided' % arg.name,
+                    arg.name))
+            else:
+                self.writeline('%s = ' % ref)
+                self.visit(default, frame)
+            self.mark_parameter_stored(ref)
+            self.outdent()
+        self.pop_parameter_definitions()
+
+        self.blockvisit(node.body, frame)
+        self.return_buffer_contents(frame, force_unescaped=True)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        return frame, macro_ref
+
+    def macro_def(self, macro_ref, frame):
+        """Dump the macro definition for the def created by macro_body."""
+        arg_tuple = ', '.join(repr(x.name) for x in macro_ref.node.args)
+        name = getattr(macro_ref.node, 'name', None)
+        if len(macro_ref.node.args) == 1:
+            arg_tuple += ','
+        self.write('Macro(environment, macro, %r, (%s), %r, %r, %r, '
+                   'context.eval_ctx.autoescape)' %
+                   (name, arg_tuple, macro_ref.accesses_kwargs,
+                    macro_ref.accesses_varargs, macro_ref.accesses_caller))
+
+    def position(self, node):
+        """Return a human readable position for the node."""
+        rv = 'line %d' % node.lineno
+        if self.name is not None:
+            rv += ' in ' + repr(self.name)
+        return rv
+
+    def dump_local_context(self, frame):
+        return '{%s}' % ', '.join(
+            '%r: %s' % (name, target) for name, target
+            in iteritems(frame.symbols.dump_stores()))
+
+    def write_commons(self):
+        """Writes a common preamble that is used by root and block functions.
+        Primarily this sets up common local helpers and enforces a generator
+        through a dead branch.
+        """
+        self.writeline('resolve = context.resolve_or_missing')
+        self.writeline('undefined = environment.undefined')
+        self.writeline('if 0: yield None')
+
+    def push_parameter_definitions(self, frame):
+        """Pushes all parameter targets from the given frame into a local
+        stack that permits tracking of yet to be assigned parameters.  In
+        particular this enables the optimization from `visit_Name` to skip
+        undefined expressions for parameters in macros as macros can reference
+        otherwise unbound parameters.
+        """
+        self._param_def_block.append(frame.symbols.dump_param_targets())
+
+    def pop_parameter_definitions(self):
+        """Pops the current parameter definitions set."""
+        self._param_def_block.pop()
+
+    def mark_parameter_stored(self, target):
+        """Marks a parameter in the current parameter definitions as stored.
+        This will skip the enforced undefined checks.
+        """
+        if self._param_def_block:
+            self._param_def_block[-1].discard(target)
+
+    def push_context_reference(self, target):
+        self._context_reference_stack.append(target)
+
+    def pop_context_reference(self):
+        self._context_reference_stack.pop()
+
+    def get_context_ref(self):
+        return self._context_reference_stack[-1]
+
+    def get_resolve_func(self):
+        target = self._context_reference_stack[-1]
+        if target == 'context':
+            return 'resolve'
+        return '%s.resolve' % target
+
+    def derive_context(self, frame):
+        return '%s.derived(%s)' % (
+            self.get_context_ref(),
+            self.dump_local_context(frame),
+        )
+
+    def parameter_is_undeclared(self, target):
+        """Checks if a given target is an undeclared parameter."""
+        if not self._param_def_block:
+            return False
+        return target in self._param_def_block[-1]
+
+    def push_assign_tracking(self):
+        """Pushes a new layer for assignment tracking."""
+        self._assign_stack.append(set())
+
+    def pop_assign_tracking(self, frame):
+        """Pops the topmost level for assignment tracking and updates the
+        context variables if necessary.
+        """
+        vars = self._assign_stack.pop()
+        if not frame.toplevel or not vars:
+            return
+        public_names = [x for x in vars if x[:1] != '_']
+        if len(vars) == 1:
+            name = next(iter(vars))
+            ref = frame.symbols.ref(name)
+            self.writeline('context.vars[%r] = %s' % (name, ref))
+        else:
+            self.writeline('context.vars.update({')
+            for idx, name in enumerate(vars):
+                if idx:
+                    self.write(', ')
+                ref = frame.symbols.ref(name)
+                self.write('%r: %s' % (name, ref))
+            self.write('})')
+        if public_names:
+            if len(public_names) == 1:
+                self.writeline('context.exported_vars.add(%r)' %
+                               public_names[0])
+            else:
+                self.writeline('context.exported_vars.update((%s))' %
+                               ', '.join(imap(repr, public_names)))
+
+    # -- Statement Visitors
+
+    def visit_Template(self, node, frame=None):
+        assert frame is None, 'no root frame allowed'
+        eval_ctx = EvalContext(self.environment, self.name)
+
+        from jinja2.runtime import __all__ as exported
+        self.writeline('from __future__ import %s' % ', '.join(code_features))
+        self.writeline('from jinja2.runtime import ' + ', '.join(exported))
+
+        if self.environment.is_async:
+            self.writeline('from jinja2.asyncsupport import auto_await, '
+                           'auto_aiter, make_async_loop_context')
+
+        # if we want a deferred initialization we cannot move the
+        # environment into a local name
+        envenv = not self.defer_init and ', environment=environment' or ''
+
+        # do we have an extends tag at all?  If not, we can save some
+        # overhead by just not processing any inheritance code.
+        have_extends = node.find(nodes.Extends) is not None
+
+        # find all blocks
+        for block in node.find_all(nodes.Block):
+            if block.name in self.blocks:
+                self.fail('block %r defined twice' % block.name, block.lineno)
+            self.blocks[block.name] = block
+
+        # find all imports and import them
+        for import_ in node.find_all(nodes.ImportedName):
+            if import_.importname not in self.import_aliases:
+                imp = import_.importname
+                self.import_aliases[imp] = alias = self.temporary_identifier()
+                if '.' in imp:
+                    module, obj = imp.rsplit('.', 1)
+                    self.writeline('from %s import %s as %s' %
+                                   (module, obj, alias))
+                else:
+                    self.writeline('import %s as %s' % (imp, alias))
+
+        # add the load name
+        self.writeline('name = %r' % self.name)
+
+        # generate the root render function.
+        self.writeline('%s(context, missing=missing%s):' %
+                       (self.func('root'), envenv), extra=1)
+        self.indent()
+        self.write_commons()
+
+        # process the root
+        frame = Frame(eval_ctx)
+        if 'self' in find_undeclared(node.body, ('self',)):
+            ref = frame.symbols.declare_parameter('self')
+            self.writeline('%s = TemplateReference(context)' % ref)
+        frame.symbols.analyze_node(node)
+        frame.toplevel = frame.rootlevel = True
+        frame.require_output_check = have_extends and not self.has_known_extends
+        if have_extends:
+            self.writeline('parent_template = None')
+        self.enter_frame(frame)
+        self.pull_dependencies(node.body)
+        self.blockvisit(node.body, frame)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        # make sure that the parent root is called.
+        if have_extends:
+            if not self.has_known_extends:
+                self.indent()
+                self.writeline('if parent_template is not None:')
+            self.indent()
+            if supports_yield_from and not self.environment.is_async:
+                self.writeline('yield from parent_template.'
+                               'root_render_func(context)')
+            else:
+                self.writeline('%sfor event in parent_template.'
+                               'root_render_func(context):' %
+                               (self.environment.is_async and 'async ' or ''))
+                self.indent()
+                self.writeline('yield event')
+                self.outdent()
+            self.outdent(1 + (not self.has_known_extends))
+
+        # at this point we now have the blocks collected and can visit them too.
+        for name, block in iteritems(self.blocks):
+            self.writeline('%s(context, missing=missing%s):' %
+                           (self.func('block_' + name), envenv),
+                           block, 1)
+            self.indent()
+            self.write_commons()
+            # It's important that we do not make this frame a child of the
+            # toplevel template.  This would cause a variety of
+            # interesting issues with identifier tracking.
+            block_frame = Frame(eval_ctx)
+            undeclared = find_undeclared(block.body, ('self', 'super'))
+            if 'self' in undeclared:
+                ref = block_frame.symbols.declare_parameter('self')
+                self.writeline('%s = TemplateReference(context)' % ref)
+            if 'super' in undeclared:
+                ref = block_frame.symbols.declare_parameter('super')
+                self.writeline('%s = context.super(%r, '
+                               'block_%s)' % (ref, name, name))
+            block_frame.symbols.analyze_node(block)
+            block_frame.block = name
+            self.enter_frame(block_frame)
+            self.pull_dependencies(block.body)
+            self.blockvisit(block.body, block_frame)
+            self.leave_frame(block_frame, with_python_scope=True)
+            self.outdent()
+
+        self.writeline('blocks = {%s}' % ', '.join('%r: block_%s' % (x, x)
+                                                   for x in self.blocks),
+                       extra=1)
+
+        # add a function that returns the debug info
+        self.writeline('debug_info = %r' % '&'.join('%s=%s' % x for x
+                                                    in self.debug_info))
+
+    def visit_Block(self, node, frame):
+        """Call a block and register it for the template."""
+        level = 0
+        if frame.toplevel:
+            # if we know that we are a child template, there is no need to
+            # check if we are one
+            if self.has_known_extends:
+                return
+            if self.extends_so_far > 0:
+                self.writeline('if parent_template is None:')
+                self.indent()
+                level += 1
+
+        if node.scoped:
+            context = self.derive_context(frame)
+        else:
+            context = self.get_context_ref()
+
+        if supports_yield_from and not self.environment.is_async and \
+           frame.buffer is None:
+            self.writeline('yield from context.blocks[%r][0](%s)' % (
+                           node.name, context), node)
+        else:
+            loop = self.environment.is_async and 'async for' or 'for'
+            self.writeline('%s event in context.blocks[%r][0](%s):' % (
+                           loop, node.name, context), node)
+            self.indent()
+            self.simple_write('event', frame)
+            self.outdent()
+
+        self.outdent(level)
+
+    def visit_Extends(self, node, frame):
+        """Calls the extender."""
+        if not frame.toplevel:
+            self.fail('cannot use extend from a non top-level scope',
+                      node.lineno)
+
+        # if the number of extends statements in general is zero so
+        # far, we don't have to add a check if something extended
+        # the template before this one.
+        if self.extends_so_far > 0:
+
+            # if we have a known extends we just add a template runtime
+            # error into the generated code.  We could catch that at compile
+            # time too, but i welcome it not to confuse users by throwing the
+            # same error at different times just "because we can".
+            if not self.has_known_extends:
+                self.writeline('if parent_template is not None:')
+                self.indent()
+            self.writeline('raise TemplateRuntimeError(%r)' %
+                           'extended multiple times')
+
+            # if we have a known extends already we don't need that code here
+            # as we know that the template execution will end here.
+            if self.has_known_extends:
+                raise CompilerExit()
+            else:
+                self.outdent()
+
+        self.writeline('parent_template = environment.get_template(', node)
+        self.visit(node.template, frame)
+        self.write(', %r)' % self.name)
+        self.writeline('for name, parent_block in parent_template.'
+                       'blocks.%s():' % dict_item_iter)
+        self.indent()
+        self.writeline('context.blocks.setdefault(name, []).'
+                       'append(parent_block)')
+        self.outdent()
+
+        # if this extends statement was in the root level we can take
+        # advantage of that information and simplify the generated code
+        # in the top level from this point onwards
+        if frame.rootlevel:
+            self.has_known_extends = True
+
+        # and now we have one more
+        self.extends_so_far += 1
+
+    def visit_Include(self, node, frame):
+        """Handles includes."""
+        if node.ignore_missing:
+            self.writeline('try:')
+            self.indent()
+
+        func_name = 'get_or_select_template'
+        if isinstance(node.template, nodes.Const):
+            if isinstance(node.template.value, string_types):
+                func_name = 'get_template'
+            elif isinstance(node.template.value, (tuple, list)):
+                func_name = 'select_template'
+        elif isinstance(node.template, (nodes.Tuple, nodes.List)):
+            func_name = 'select_template'
+
+        self.writeline('template = environment.%s(' % func_name, node)
+        self.visit(node.template, frame)
+        self.write(', %r)' % self.name)
+        if node.ignore_missing:
+            self.outdent()
+            self.writeline('except TemplateNotFound:')
+            self.indent()
+            self.writeline('pass')
+            self.outdent()
+            self.writeline('else:')
+            self.indent()
+
+        skip_event_yield = False
+        if node.with_context:
+            loop = self.environment.is_async and 'async for' or 'for'
+            self.writeline('%s event in template.root_render_func('
+                           'template.new_context(context.get_all(), True, '
+                           '%s)):' % (loop, self.dump_local_context(frame)))
+        elif self.environment.is_async:
+            self.writeline('for event in (await '
+                           'template._get_default_module_async())'
+                           '._body_stream:')
+        else:
+            if supports_yield_from:
+                self.writeline('yield from template._get_default_module()'
+                               '._body_stream')
+                skip_event_yield = True
+            else:
+                self.writeline('for event in template._get_default_module()'
+                               '._body_stream:')
+
+        if not skip_event_yield:
+            self.indent()
+            self.simple_write('event', frame)
+            self.outdent()
+
+        if node.ignore_missing:
+            self.outdent()
+
+    def visit_Import(self, node, frame):
+        """Visit regular imports."""
+        self.writeline('%s = ' % frame.symbols.ref(node.target), node)
+        if frame.toplevel:
+            self.write('context.vars[%r] = ' % node.target)
+        if self.environment.is_async:
+            self.write('await ')
+        self.write('environment.get_template(')
+        self.visit(node.template, frame)
+        self.write(', %r).' % self.name)
+        if node.with_context:
+            self.write('make_module%s(context.get_all(), True, %s)'
+                       % (self.environment.is_async and '_async' or '',
+                          self.dump_local_context(frame)))
+        elif self.environment.is_async:
+            self.write('_get_default_module_async()')
+        else:
+            self.write('_get_default_module()')
+        if frame.toplevel and not node.target.startswith('_'):
+            self.writeline('context.exported_vars.discard(%r)' % node.target)
+
+    def visit_FromImport(self, node, frame):
+        """Visit named imports."""
+        self.newline(node)
+        self.write('included_template = %senvironment.get_template('
+                   % (self.environment.is_async and 'await ' or ''))
+        self.visit(node.template, frame)
+        self.write(', %r).' % self.name)
+        if node.with_context:
+            self.write('make_module%s(context.get_all(), True, %s)'
+                       % (self.environment.is_async and '_async' or '',
+                          self.dump_local_context(frame)))
+        elif self.environment.is_async:
+            self.write('_get_default_module_async()')
+        else:
+            self.write('_get_default_module()')
+
+        var_names = []
+        discarded_names = []
+        for name in node.names:
+            if isinstance(name, tuple):
+                name, alias = name
+            else:
+                alias = name
+            self.writeline('%s = getattr(included_template, '
+                           '%r, missing)' % (frame.symbols.ref(alias), name))
+            self.writeline('if %s is missing:' % frame.symbols.ref(alias))
+            self.indent()
+            self.writeline('%s = undefined(%r %% '
+                           'included_template.__name__, '
+                           'name=%r)' %
+                           (frame.symbols.ref(alias),
+                            'the template %%r (imported on %s) does '
+                            'not export the requested name %s' % (
+                                self.position(node),
+                                repr(name)
+                           ), name))
+            self.outdent()
+            if frame.toplevel:
+                var_names.append(alias)
+                if not alias.startswith('_'):
+                    discarded_names.append(alias)
+
+        if var_names:
+            if len(var_names) == 1:
+                name = var_names[0]
+                self.writeline('context.vars[%r] = %s' %
+                               (name, frame.symbols.ref(name)))
+            else:
+                self.writeline('context.vars.update({%s})' % ', '.join(
+                    '%r: %s' % (name, frame.symbols.ref(name)) for name in var_names
+                ))
+        if discarded_names:
+            if len(discarded_names) == 1:
+                self.writeline('context.exported_vars.discard(%r)' %
+                               discarded_names[0])
+            else:
+                self.writeline('context.exported_vars.difference_'
+                               'update((%s))' % ', '.join(imap(repr, discarded_names)))
+
+    def visit_For(self, node, frame):
+        loop_frame = frame.inner()
+        test_frame = frame.inner()
+        else_frame = frame.inner()
+
+        # try to figure out if we have an extended loop.  An extended loop
+        # is necessary if the loop is in recursive mode if the special loop
+        # variable is accessed in the body.
+        extended_loop = node.recursive or 'loop' in \
+                        find_undeclared(node.iter_child_nodes(
+                            only=('body',)), ('loop',))
+
+        loop_ref = None
+        if extended_loop:
+            loop_ref = loop_frame.symbols.declare_parameter('loop')
+
+        loop_frame.symbols.analyze_node(node, for_branch='body')
+        if node.else_:
+            else_frame.symbols.analyze_node(node, for_branch='else')
+
+        if node.test:
+            loop_filter_func = self.temporary_identifier()
+            test_frame.symbols.analyze_node(node, for_branch='test')
+            self.writeline('%s(fiter):' % self.func(loop_filter_func), node.test)
+            self.indent()
+            self.enter_frame(test_frame)
+            self.writeline(self.environment.is_async and 'async for ' or 'for ')
+            self.visit(node.target, loop_frame)
+            self.write(' in ')
+            self.write(self.environment.is_async and 'auto_aiter(fiter)' or 'fiter')
+            self.write(':')
+            self.indent()
+            self.writeline('if ', node.test)
+            self.visit(node.test, test_frame)
+            self.write(':')
+            self.indent()
+            self.writeline('yield ')
+            self.visit(node.target, loop_frame)
+            self.outdent(3)
+            self.leave_frame(test_frame, with_python_scope=True)
+
+        # if we don't have an recursive loop we have to find the shadowed
+        # variables at that point.  Because loops can be nested but the loop
+        # variable is a special one we have to enforce aliasing for it.
+        if node.recursive:
+            self.writeline('%s(reciter, loop_render_func, depth=0):' %
+                           self.func('loop'), node)
+            self.indent()
+            self.buffer(loop_frame)
+
+            # Use the same buffer for the else frame
+            else_frame.buffer = loop_frame.buffer
+
+        # make sure the loop variable is a special one and raise a template
+        # assertion error if a loop tries to write to loop
+        if extended_loop:
+            self.writeline('%s = missing' % loop_ref)
+
+        for name in node.find_all(nodes.Name):
+            if name.ctx == 'store' and name.name == 'loop':
+                self.fail('Can\'t assign to special loop variable '
+                          'in for-loop target', name.lineno)
+
+        if node.else_:
+            iteration_indicator = self.temporary_identifier()
+            self.writeline('%s = 1' % iteration_indicator)
+
+        self.writeline(self.environment.is_async and 'async for ' or 'for ', node)
+        self.visit(node.target, loop_frame)
+        if extended_loop:
+            if self.environment.is_async:
+                self.write(', %s in await make_async_loop_context(' % loop_ref)
+            else:
+                self.write(', %s in LoopContext(' % loop_ref)
+        else:
+            self.write(' in ')
+
+        if node.test:
+            self.write('%s(' % loop_filter_func)
+        if node.recursive:
+            self.write('reciter')
+        else:
+            if self.environment.is_async and not extended_loop:
+                self.write('auto_aiter(')
+            self.visit(node.iter, frame)
+            if self.environment.is_async and not extended_loop:
+                self.write(')')
+        if node.test:
+            self.write(')')
+
+        if node.recursive:
+            self.write(', undefined, loop_render_func, depth):')
+        else:
+            self.write(extended_loop and ', undefined):' or ':')
+
+        self.indent()
+        self.enter_frame(loop_frame)
+
+        self.blockvisit(node.body, loop_frame)
+        if node.else_:
+            self.writeline('%s = 0' % iteration_indicator)
+        self.outdent()
+        self.leave_frame(loop_frame, with_python_scope=node.recursive
+                         and not node.else_)
+
+        if node.else_:
+            self.writeline('if %s:' % iteration_indicator)
+            self.indent()
+            self.enter_frame(else_frame)
+            self.blockvisit(node.else_, else_frame)
+            self.leave_frame(else_frame)
+            self.outdent()
+
+        # if the node was recursive we have to return the buffer contents
+        # and start the iteration code
+        if node.recursive:
+            self.return_buffer_contents(loop_frame)
+            self.outdent()
+            self.start_write(frame, node)
+            if self.environment.is_async:
+                self.write('await ')
+            self.write('loop(')
+            if self.environment.is_async:
+                self.write('auto_aiter(')
+            self.visit(node.iter, frame)
+            if self.environment.is_async:
+                self.write(')')
+            self.write(', loop)')
+            self.end_write(frame)
+
+    def visit_If(self, node, frame):
+        if_frame = frame.soft()
+        self.writeline('if ', node)
+        self.visit(node.test, if_frame)
+        self.write(':')
+        self.indent()
+        self.blockvisit(node.body, if_frame)
+        self.outdent()
+        for elif_ in node.elif_:
+            self.writeline('elif ', elif_)
+            self.visit(elif_.test, if_frame)
+            self.write(':')
+            self.indent()
+            self.blockvisit(elif_.body, if_frame)
+            self.outdent()
+        if node.else_:
+            self.writeline('else:')
+            self.indent()
+            self.blockvisit(node.else_, if_frame)
+            self.outdent()
+
+    def visit_Macro(self, node, frame):
+        macro_frame, macro_ref = self.macro_body(node, frame)
+        self.newline()
+        if frame.toplevel:
+            if not node.name.startswith('_'):
+                self.write('context.exported_vars.add(%r)' % node.name)
+            ref = frame.symbols.ref(node.name)
+            self.writeline('context.vars[%r] = ' % node.name)
+        self.write('%s = ' % frame.symbols.ref(node.name))
+        self.macro_def(macro_ref, macro_frame)
+
+    def visit_CallBlock(self, node, frame):
+        call_frame, macro_ref = self.macro_body(node, frame)
+        self.writeline('caller = ')
+        self.macro_def(macro_ref, call_frame)
+        self.start_write(frame, node)
+        self.visit_Call(node.call, frame, forward_caller=True)
+        self.end_write(frame)
+
+    def visit_FilterBlock(self, node, frame):
+        filter_frame = frame.inner()
+        filter_frame.symbols.analyze_node(node)
+        self.enter_frame(filter_frame)
+        self.buffer(filter_frame)
+        self.blockvisit(node.body, filter_frame)
+        self.start_write(frame, node)
+        self.visit_Filter(node.filter, filter_frame)
+        self.end_write(frame)
+        self.leave_frame(filter_frame)
+
+    def visit_With(self, node, frame):
+        with_frame = frame.inner()
+        with_frame.symbols.analyze_node(node)
+        self.enter_frame(with_frame)
+        for idx, (target, expr) in enumerate(izip(node.targets, node.values)):
+            self.newline()
+            self.visit(target, with_frame)
+            self.write(' = ')
+            self.visit(expr, frame)
+        self.blockvisit(node.body, with_frame)
+        self.leave_frame(with_frame)
+
+    def visit_ExprStmt(self, node, frame):
+        self.newline(node)
+        self.visit(node.node, frame)
+
+    def visit_Output(self, node, frame):
+        # if we have a known extends statement, we don't output anything
+        # if we are in a require_output_check section
+        if self.has_known_extends and frame.require_output_check:
+            return
+
+        allow_constant_finalize = True
+        if self.environment.finalize:
+            func = self.environment.finalize
+            if getattr(func, 'contextfunction', False) or \
+               getattr(func, 'evalcontextfunction', False):
+                allow_constant_finalize = False
+            elif getattr(func, 'environmentfunction', False):
+                finalize = lambda x: text_type(
+                    self.environment.finalize(self.environment, x))
+            else:
+                finalize = lambda x: text_type(self.environment.finalize(x))
+        else:
+            finalize = text_type
+
+        # if we are inside a frame that requires output checking, we do so
+        outdent_later = False
+        if frame.require_output_check:
+            self.writeline('if parent_template is None:')
+            self.indent()
+            outdent_later = True
+
+        # try to evaluate as many chunks as possible into a static
+        # string at compile time.
+        body = []
+        for child in node.nodes:
+            try:
+                if not allow_constant_finalize:
+                    raise nodes.Impossible()
+                const = child.as_const(frame.eval_ctx)
+            except nodes.Impossible:
+                body.append(child)
+                continue
+            # the frame can't be volatile here, becaus otherwise the
+            # as_const() function would raise an Impossible exception
+            # at that point.
+            try:
+                if frame.eval_ctx.autoescape:
+                    if hasattr(const, '__html__'):
+                        const = const.__html__()
+                    else:
+                        const = escape(const)
+                const = finalize(const)
+            except Exception:
+                # if something goes wrong here we evaluate the node
+                # at runtime for easier debugging
+                body.append(child)
+                continue
+            if body and isinstance(body[-1], list):
+                body[-1].append(const)
+            else:
+                body.append([const])
+
+        # if we have less than 3 nodes or a buffer we yield or extend/append
+        if len(body) < 3 or frame.buffer is not None:
+            if frame.buffer is not None:
+                # for one item we append, for more we extend
+                if len(body) == 1:
+                    self.writeline('%s.append(' % frame.buffer)
+                else:
+                    self.writeline('%s.extend((' % frame.buffer)
+                self.indent()
+            for item in body:
+                if isinstance(item, list):
+                    val = repr(concat(item))
+                    if frame.buffer is None:
+                        self.writeline('yield ' + val)
+                    else:
+                        self.writeline(val + ',')
+                else:
+                    if frame.buffer is None:
+                        self.writeline('yield ', item)
+                    else:
+                        self.newline(item)
+                    close = 1
+                    if frame.eval_ctx.volatile:
+                        self.write('(escape if context.eval_ctx.autoescape'
+                                   ' else to_string)(')
+                    elif frame.eval_ctx.autoescape:
+                        self.write('escape(')
+                    else:
+                        self.write('to_string(')
+                    if self.environment.finalize is not None:
+                        self.write('environment.finalize(')
+                        if getattr(self.environment.finalize,
+                                   "contextfunction", False):
+                            self.write('context, ')
+                        close += 1
+                    self.visit(item, frame)
+                    self.write(')' * close)
+                    if frame.buffer is not None:
+                        self.write(',')
+            if frame.buffer is not None:
+                # close the open parentheses
+                self.outdent()
+                self.writeline(len(body) == 1 and ')' or '))')
+
+        # otherwise we create a format string as this is faster in that case
+        else:
+            format = []
+            arguments = []
+            for item in body:
+                if isinstance(item, list):
+                    format.append(concat(item).replace('%', '%%'))
+                else:
+                    format.append('%s')
+                    arguments.append(item)
+            self.writeline('yield ')
+            self.write(repr(concat(format)) + ' % (')
+            self.indent()
+            for argument in arguments:
+                self.newline(argument)
+                close = 0
+                if frame.eval_ctx.volatile:
+                    self.write('(escape if context.eval_ctx.autoescape else'
+                               ' to_string)(')
+                    close += 1
+                elif frame.eval_ctx.autoescape:
+                    self.write('escape(')
+                    close += 1
+                if self.environment.finalize is not None:
+                    self.write('environment.finalize(')
+                    if getattr(self.environment.finalize,
+                               'contextfunction', False):
+                        self.write('context, ')
+                    elif getattr(self.environment.finalize,
+                               'evalcontextfunction', False):
+                        self.write('context.eval_ctx, ')
+                    elif getattr(self.environment.finalize,
+                               'environmentfunction', False):
+                        self.write('environment, ')
+                    close += 1
+                self.visit(argument, frame)
+                self.write(')' * close + ', ')
+            self.outdent()
+            self.writeline(')')
+
+        if outdent_later:
+            self.outdent()
+
+    def visit_Assign(self, node, frame):
+        self.push_assign_tracking()
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(' = ')
+        self.visit(node.node, frame)
+        self.pop_assign_tracking(frame)
+
+    def visit_AssignBlock(self, node, frame):
+        self.push_assign_tracking()
+        block_frame = frame.inner()
+        # This is a special case.  Since a set block always captures we
+        # will disable output checks.  This way one can use set blocks
+        # toplevel even in extended templates.
+        block_frame.require_output_check = False
+        block_frame.symbols.analyze_node(node)
+        self.enter_frame(block_frame)
+        self.buffer(block_frame)
+        self.blockvisit(node.body, block_frame)
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(' = (Markup if context.eval_ctx.autoescape '
+                   'else identity)(')
+        if node.filter is not None:
+            self.visit_Filter(node.filter, block_frame)
+        else:
+            self.write('concat(%s)' % block_frame.buffer)
+        self.write(')')
+        self.pop_assign_tracking(frame)
+        self.leave_frame(block_frame)
+
+    # -- Expression Visitors
+
+    def visit_Name(self, node, frame):
+        if node.ctx == 'store' and frame.toplevel:
+            if self._assign_stack:
+                self._assign_stack[-1].add(node.name)
+        ref = frame.symbols.ref(node.name)
+
+        # If we are looking up a variable we might have to deal with the
+        # case where it's undefined.  We can skip that case if the load
+        # instruction indicates a parameter which are always defined.
+        if node.ctx == 'load':
+            load = frame.symbols.find_load(ref)
+            if not (load is not None and load[0] == VAR_LOAD_PARAMETER and \
+                    not self.parameter_is_undeclared(ref)):
+                self.write('(undefined(name=%r) if %s is missing else %s)' %
+                           (node.name, ref, ref))
+                return
+
+        self.write(ref)
+
+    def visit_NSRef(self, node, frame):
+        # NSRefs can only be used to store values; since they use the normal
+        # `foo.bar` notation they will be parsed as a normal attribute access
+        # when used anywhere but in a `set` context
+        ref = frame.symbols.ref(node.name)
+        self.writeline('if not isinstance(%s, Namespace):' % ref)
+        self.indent()
+        self.writeline('raise TemplateRuntimeError(%r)' %
+                       'cannot assign attribute on non-namespace object')
+        self.outdent()
+        self.writeline('%s[%r]' % (ref, node.attr))
+
+    def visit_Const(self, node, frame):
+        val = node.as_const(frame.eval_ctx)
+        if isinstance(val, float):
+            self.write(str(val))
+        else:
+            self.write(repr(val))
+
+    def visit_TemplateData(self, node, frame):
+        try:
+            self.write(repr(node.as_const(frame.eval_ctx)))
+        except nodes.Impossible:
+            self.write('(Markup if context.eval_ctx.autoescape else identity)(%r)'
+                       % node.data)
+
+    def visit_Tuple(self, node, frame):
+        self.write('(')
+        idx = -1
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(', ')
+            self.visit(item, frame)
+        self.write(idx == 0 and ',)' or ')')
+
+    def visit_List(self, node, frame):
+        self.write('[')
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(', ')
+            self.visit(item, frame)
+        self.write(']')
+
+    def visit_Dict(self, node, frame):
+        self.write('{')
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(', ')
+            self.visit(item.key, frame)
+            self.write(': ')
+            self.visit(item.value, frame)
+        self.write('}')
+
+    def binop(operator, interceptable=True):
+        @optimizeconst
+        def visitor(self, node, frame):
+            if self.environment.sandboxed and \
+               operator in self.environment.intercepted_binops:
+                self.write('environment.call_binop(context, %r, ' % operator)
+                self.visit(node.left, frame)
+                self.write(', ')
+                self.visit(node.right, frame)
+            else:
+                self.write('(')
+                self.visit(node.left, frame)
+                self.write(' %s ' % operator)
+                self.visit(node.right, frame)
+            self.write(')')
+        return visitor
+
+    def uaop(operator, interceptable=True):
+        @optimizeconst
+        def visitor(self, node, frame):
+            if self.environment.sandboxed and \
+               operator in self.environment.intercepted_unops:
+                self.write('environment.call_unop(context, %r, ' % operator)
+                self.visit(node.node, frame)
+            else:
+                self.write('(' + operator)
+                self.visit(node.node, frame)
+            self.write(')')
+        return visitor
+
+    visit_Add = binop('+')
+    visit_Sub = binop('-')
+    visit_Mul = binop('*')
+    visit_Div = binop('/')
+    visit_FloorDiv = binop('//')
+    visit_Pow = binop('**')
+    visit_Mod = binop('%')
+    visit_And = binop('and', interceptable=False)
+    visit_Or = binop('or', interceptable=False)
+    visit_Pos = uaop('+')
+    visit_Neg = uaop('-')
+    visit_Not = uaop('not ', interceptable=False)
+    del binop, uaop
+
+    @optimizeconst
+    def visit_Concat(self, node, frame):
+        if frame.eval_ctx.volatile:
+            func_name = '(context.eval_ctx.volatile and' \
+                        ' markup_join or unicode_join)'
+        elif frame.eval_ctx.autoescape:
+            func_name = 'markup_join'
+        else:
+            func_name = 'unicode_join'
+        self.write('%s((' % func_name)
+        for arg in node.nodes:
+            self.visit(arg, frame)
+            self.write(', ')
+        self.write('))')
+
+    @optimizeconst
+    def visit_Compare(self, node, frame):
+        self.visit(node.expr, frame)
+        for op in node.ops:
+            self.visit(op, frame)
+
+    def visit_Operand(self, node, frame):
+        self.write(' %s ' % operators[node.op])
+        self.visit(node.expr, frame)
+
+    @optimizeconst
+    def visit_Getattr(self, node, frame):
+        self.write('environment.getattr(')
+        self.visit(node.node, frame)
+        self.write(', %r)' % node.attr)
+
+    @optimizeconst
+    def visit_Getitem(self, node, frame):
+        # slices bypass the environment getitem method.
+        if isinstance(node.arg, nodes.Slice):
+            self.visit(node.node, frame)
+            self.write('[')
+            self.visit(node.arg, frame)
+            self.write(']')
+        else:
+            self.write('environment.getitem(')
+            self.visit(node.node, frame)
+            self.write(', ')
+            self.visit(node.arg, frame)
+            self.write(')')
+
+    def visit_Slice(self, node, frame):
+        if node.start is not None:
+            self.visit(node.start, frame)
+        self.write(':')
+        if node.stop is not None:
+            self.visit(node.stop, frame)
+        if node.step is not None:
+            self.write(':')
+            self.visit(node.step, frame)
+
+    @optimizeconst
+    def visit_Filter(self, node, frame):
+        if self.environment.is_async:
+            self.write('await auto_await(')
+        self.write(self.filters[node.name] + '(')
+        func = self.environment.filters.get(node.name)
+        if func is None:
+            self.fail('no filter named %r' % node.name, node.lineno)
+        if getattr(func, 'contextfilter', False):
+            self.write('context, ')
+        elif getattr(func, 'evalcontextfilter', False):
+            self.write('context.eval_ctx, ')
+        elif getattr(func, 'environmentfilter', False):
+            self.write('environment, ')
+
+        # if the filter node is None we are inside a filter block
+        # and want to write to the current buffer
+        if node.node is not None:
+            self.visit(node.node, frame)
+        elif frame.eval_ctx.volatile:
+            self.write('(context.eval_ctx.autoescape and'
+                       ' Markup(concat(%s)) or concat(%s))' %
+                       (frame.buffer, frame.buffer))
+        elif frame.eval_ctx.autoescape:
+            self.write('Markup(concat(%s))' % frame.buffer)
+        else:
+            self.write('concat(%s)' % frame.buffer)
+        self.signature(node, frame)
+        self.write(')')
+        if self.environment.is_async:
+            self.write(')')
+
+    @optimizeconst
+    def visit_Test(self, node, frame):
+        self.write(self.tests[node.name] + '(')
+        if node.name not in self.environment.tests:
+            self.fail('no test named %r' % node.name, node.lineno)
+        self.visit(node.node, frame)
+        self.signature(node, frame)
+        self.write(')')
+
+    @optimizeconst
+    def visit_CondExpr(self, node, frame):
+        def write_expr2():
+            if node.expr2 is not None:
+                return self.visit(node.expr2, frame)
+            self.write('undefined(%r)' % ('the inline if-'
+                       'expression on %s evaluated to false and '
+                       'no else section was defined.' % self.position(node)))
+
+        self.write('(')
+        self.visit(node.expr1, frame)
+        self.write(' if ')
+        self.visit(node.test, frame)
+        self.write(' else ')
+        write_expr2()
+        self.write(')')
+
+    @optimizeconst
+    def visit_Call(self, node, frame, forward_caller=False):
+        if self.environment.is_async:
+            self.write('await auto_await(')
+        if self.environment.sandboxed:
+            self.write('environment.call(context, ')
+        else:
+            self.write('context.call(')
+        self.visit(node.node, frame)
+        extra_kwargs = forward_caller and {'caller': 'caller'} or None
+        self.signature(node, frame, extra_kwargs)
+        self.write(')')
+        if self.environment.is_async:
+            self.write(')')
+
+    def visit_Keyword(self, node, frame):
+        self.write(node.key + '=')
+        self.visit(node.value, frame)
+
+    # -- Unused nodes for extensions
+
+    def visit_MarkSafe(self, node, frame):
+        self.write('Markup(')
+        self.visit(node.expr, frame)
+        self.write(')')
+
+    def visit_MarkSafeIfAutoescape(self, node, frame):
+        self.write('(context.eval_ctx.autoescape and Markup or identity)(')
+        self.visit(node.expr, frame)
+        self.write(')')
+
+    def visit_EnvironmentAttribute(self, node, frame):
+        self.write('environment.' + node.name)
+
+    def visit_ExtensionAttribute(self, node, frame):
+        self.write('environment.extensions[%r].%s' % (node.identifier, node.name))
+
+    def visit_ImportedName(self, node, frame):
+        self.write(self.import_aliases[node.importname])
+
+    def visit_InternalName(self, node, frame):
+        self.write(node.name)
+
+    def visit_ContextReference(self, node, frame):
+        self.write('context')
+
+    def visit_Continue(self, node, frame):
+        self.writeline('continue', node)
+
+    def visit_Break(self, node, frame):
+        self.writeline('break', node)
+
+    def visit_Scope(self, node, frame):
+        scope_frame = frame.inner()
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+
+    def visit_OverlayScope(self, node, frame):
+        ctx = self.temporary_identifier()
+        self.writeline('%s = %s' % (ctx, self.derive_context(frame)))
+        self.writeline('%s.vars = ' % ctx)
+        self.visit(node.context, frame)
+        self.push_context_reference(ctx)
+
+        scope_frame = frame.inner(isolated=True)
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+        self.pop_context_reference()
+
+    def visit_EvalContextModifier(self, node, frame):
+        for keyword in node.options:
+            self.writeline('context.eval_ctx.%s = ' % keyword.key)
+            self.visit(keyword.value, frame)
+            try:
+                val = keyword.value.as_const(frame.eval_ctx)
+            except nodes.Impossible:
+                frame.eval_ctx.volatile = True
+            else:
+                setattr(frame.eval_ctx, keyword.key, val)
+
+    def visit_ScopedEvalContextModifier(self, node, frame):
+        old_ctx_name = self.temporary_identifier()
+        saved_ctx = frame.eval_ctx.save()
+        self.writeline('%s = context.eval_ctx.save()' % old_ctx_name)
+        self.visit_EvalContextModifier(node, frame)
+        for child in node.body:
+            self.visit(child, frame)
+        frame.eval_ctx.revert(saved_ctx)
+        self.writeline('context.eval_ctx.revert(%s)' % old_ctx_name)
diff --git a/python/jinja2/constants.py b/python/jinja2/constants.py
new file mode 100644
index 0000000..11efd1e
--- /dev/null
+++ b/python/jinja2/constants.py
@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja.constants
+    ~~~~~~~~~~~~~~~
+
+    Various constants.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+
+
+#: list of lorem ipsum words used by the lipsum() helper function
+LOREM_IPSUM_WORDS = u'''\
+a ac accumsan ad adipiscing aenean aliquam aliquet amet ante aptent arcu at
+auctor augue bibendum blandit class commodo condimentum congue consectetuer
+consequat conubia convallis cras cubilia cum curabitur curae cursus dapibus
+diam dictum dictumst dignissim dis dolor donec dui duis egestas eget eleifend
+elementum elit enim erat eros est et etiam eu euismod facilisi facilisis fames
+faucibus felis fermentum feugiat fringilla fusce gravida habitant habitasse hac
+hendrerit hymenaeos iaculis id imperdiet in inceptos integer interdum ipsum
+justo lacinia lacus laoreet lectus leo libero ligula litora lobortis lorem
+luctus maecenas magna magnis malesuada massa mattis mauris metus mi molestie
+mollis montes morbi mus nam nascetur natoque nec neque netus nibh nisi nisl non
+nonummy nostra nulla nullam nunc odio orci ornare parturient pede pellentesque
+penatibus per pharetra phasellus placerat platea porta porttitor posuere
+potenti praesent pretium primis proin pulvinar purus quam quis quisque rhoncus
+ridiculus risus rutrum sagittis sapien scelerisque sed sem semper senectus sit
+sociis sociosqu sodales sollicitudin suscipit suspendisse taciti tellus tempor
+tempus tincidunt torquent tortor tristique turpis ullamcorper ultrices
+ultricies urna ut varius vehicula vel velit venenatis vestibulum vitae vivamus
+viverra volutpat vulputate'''
diff --git a/python/jinja2/debug.py b/python/jinja2/debug.py
new file mode 100644
index 0000000..b61139f
--- /dev/null
+++ b/python/jinja2/debug.py
@@ -0,0 +1,372 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.debug
+    ~~~~~~~~~~~~
+
+    Implements the debug interface for Jinja.  This module does some pretty
+    ugly stuff with the Python traceback system in order to achieve tracebacks
+    with correct line numbers, locals and contents.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import sys
+import traceback
+from types import TracebackType, CodeType
+from jinja2.utils import missing, internal_code
+from jinja2.exceptions import TemplateSyntaxError
+from jinja2._compat import iteritems, reraise, PY2
+
+# on pypy we can take advantage of transparent proxies
+try:
+    from __pypy__ import tproxy
+except ImportError:
+    tproxy = None
+
+
+# how does the raise helper look like?
+try:
+    exec("raise TypeError, 'foo'")
+except SyntaxError:
+    raise_helper = 'raise __jinja_exception__[1]'
+except TypeError:
+    raise_helper = 'raise __jinja_exception__[0], __jinja_exception__[1]'
+
+
+class TracebackFrameProxy(object):
+    """Proxies a traceback frame."""
+
+    def __init__(self, tb):
+        self.tb = tb
+        self._tb_next = None
+
+    @property
+    def tb_next(self):
+        return self._tb_next
+
+    def set_next(self, next):
+        if tb_set_next is not None:
+            try:
+                tb_set_next(self.tb, next and next.tb or None)
+            except Exception:
+                # this function can fail due to all the hackery it does
+                # on various python implementations.  We just catch errors
+                # down and ignore them if necessary.
+                pass
+        self._tb_next = next
+
+    @property
+    def is_jinja_frame(self):
+        return '__jinja_template__' in self.tb.tb_frame.f_globals
+
+    def __getattr__(self, name):
+        return getattr(self.tb, name)
+
+
+def make_frame_proxy(frame):
+    proxy = TracebackFrameProxy(frame)
+    if tproxy is None:
+        return proxy
+    def operation_handler(operation, *args, **kwargs):
+        if operation in ('__getattribute__', '__getattr__'):
+            return getattr(proxy, args[0])
+        elif operation == '__setattr__':
+            proxy.__setattr__(*args, **kwargs)
+        else:
+            return getattr(proxy, operation)(*args, **kwargs)
+    return tproxy(TracebackType, operation_handler)
+
+
+class ProcessedTraceback(object):
+    """Holds a Jinja preprocessed traceback for printing or reraising."""
+
+    def __init__(self, exc_type, exc_value, frames):
+        assert frames, 'no frames for this traceback?'
+        self.exc_type = exc_type
+        self.exc_value = exc_value
+        self.frames = frames
+
+        # newly concatenate the frames (which are proxies)
+        prev_tb = None
+        for tb in self.frames:
+            if prev_tb is not None:
+                prev_tb.set_next(tb)
+            prev_tb = tb
+        prev_tb.set_next(None)
+
+    def render_as_text(self, limit=None):
+        """Return a string with the traceback."""
+        lines = traceback.format_exception(self.exc_type, self.exc_value,
+                                           self.frames[0], limit=limit)
+        return ''.join(lines).rstrip()
+
+    def render_as_html(self, full=False):
+        """Return a unicode string with the traceback as rendered HTML."""
+        from jinja2.debugrenderer import render_traceback
+        return u'%s\n\n<!--\n%s\n-->' % (
+            render_traceback(self, full=full),
+            self.render_as_text().decode('utf-8', 'replace')
+        )
+
+    @property
+    def is_template_syntax_error(self):
+        """`True` if this is a template syntax error."""
+        return isinstance(self.exc_value, TemplateSyntaxError)
+
+    @property
+    def exc_info(self):
+        """Exception info tuple with a proxy around the frame objects."""
+        return self.exc_type, self.exc_value, self.frames[0]
+
+    @property
+    def standard_exc_info(self):
+        """Standard python exc_info for re-raising"""
+        tb = self.frames[0]
+        # the frame will be an actual traceback (or transparent proxy) if
+        # we are on pypy or a python implementation with support for tproxy
+        if type(tb) is not TracebackType:
+            tb = tb.tb
+        return self.exc_type, self.exc_value, tb
+
+
+def make_traceback(exc_info, source_hint=None):
+    """Creates a processed traceback object from the exc_info."""
+    exc_type, exc_value, tb = exc_info
+    if isinstance(exc_value, TemplateSyntaxError):
+        exc_info = translate_syntax_error(exc_value, source_hint)
+        initial_skip = 0
+    else:
+        initial_skip = 1
+    return translate_exception(exc_info, initial_skip)
+
+
+def translate_syntax_error(error, source=None):
+    """Rewrites a syntax error to please traceback systems."""
+    error.source = source
+    error.translated = True
+    exc_info = (error.__class__, error, None)
+    filename = error.filename
+    if filename is None:
+        filename = '<unknown>'
+    return fake_exc_info(exc_info, filename, error.lineno)
+
+
+def translate_exception(exc_info, initial_skip=0):
+    """If passed an exc_info it will automatically rewrite the exceptions
+    all the way down to the correct line numbers and frames.
+    """
+    tb = exc_info[2]
+    frames = []
+
+    # skip some internal frames if wanted
+    for x in range(initial_skip):
+        if tb is not None:
+            tb = tb.tb_next
+    initial_tb = tb
+
+    while tb is not None:
+        # skip frames decorated with @internalcode.  These are internal
+        # calls we can't avoid and that are useless in template debugging
+        # output.
+        if tb.tb_frame.f_code in internal_code:
+            tb = tb.tb_next
+            continue
+
+        # save a reference to the next frame if we override the current
+        # one with a faked one.
+        next = tb.tb_next
+
+        # fake template exceptions
+        template = tb.tb_frame.f_globals.get('__jinja_template__')
+        if template is not None:
+            lineno = template.get_corresponding_lineno(tb.tb_lineno)
+            tb = fake_exc_info(exc_info[:2] + (tb,), template.filename,
+                               lineno)[2]
+
+        frames.append(make_frame_proxy(tb))
+        tb = next
+
+    # if we don't have any exceptions in the frames left, we have to
+    # reraise it unchanged.
+    # XXX: can we backup here?  when could this happen?
+    if not frames:
+        reraise(exc_info[0], exc_info[1], exc_info[2])
+
+    return ProcessedTraceback(exc_info[0], exc_info[1], frames)
+
+
+def get_jinja_locals(real_locals):
+    ctx = real_locals.get('context')
+    if ctx:
+        locals = ctx.get_all().copy()
+    else:
+        locals = {}
+
+    local_overrides = {}
+
+    for name, value in iteritems(real_locals):
+        if not name.startswith('l_') or value is missing:
+            continue
+        try:
+            _, depth, name = name.split('_', 2)
+            depth = int(depth)
+        except ValueError:
+            continue
+        cur_depth = local_overrides.get(name, (-1,))[0]
+        if cur_depth < depth:
+            local_overrides[name] = (depth, value)
+
+    for name, (_, value) in iteritems(local_overrides):
+        if value is missing:
+            locals.pop(name, None)
+        else:
+            locals[name] = value
+
+    return locals
+
+
+def fake_exc_info(exc_info, filename, lineno):
+    """Helper for `translate_exception`."""
+    exc_type, exc_value, tb = exc_info
+
+    # figure the real context out
+    if tb is not None:
+        locals = get_jinja_locals(tb.tb_frame.f_locals)
+
+        # if there is a local called __jinja_exception__, we get
+        # rid of it to not break the debug functionality.
+        locals.pop('__jinja_exception__', None)
+    else:
+        locals = {}
+
+    # assamble fake globals we need
+    globals = {
+        '__name__':             filename,
+        '__file__':             filename,
+        '__jinja_exception__':  exc_info[:2],
+
+        # we don't want to keep the reference to the template around
+        # to not cause circular dependencies, but we mark it as Jinja
+        # frame for the ProcessedTraceback
+        '__jinja_template__':   None
+    }
+
+    # and fake the exception
+    code = compile('\n' * (lineno - 1) + raise_helper, filename, 'exec')
+
+    # if it's possible, change the name of the code.  This won't work
+    # on some python environments such as google appengine
+    try:
+        if tb is None:
+            location = 'template'
+        else:
+            function = tb.tb_frame.f_code.co_name
+            if function == 'root':
+                location = 'top-level template code'
+            elif function.startswith('block_'):
+                location = 'block "%s"' % function[6:]
+            else:
+                location = 'template'
+
+        if PY2:
+            code = CodeType(0, code.co_nlocals, code.co_stacksize,
+                            code.co_flags, code.co_code, code.co_consts,
+                            code.co_names, code.co_varnames, filename,
+                            location, code.co_firstlineno,
+                            code.co_lnotab, (), ())
+        else:
+            code = CodeType(0, code.co_kwonlyargcount,
+                            code.co_nlocals, code.co_stacksize,
+                            code.co_flags, code.co_code, code.co_consts,
+                            code.co_names, code.co_varnames, filename,
+                            location, code.co_firstlineno,
+                            code.co_lnotab, (), ())
+    except Exception as e:
+        pass
+
+    # execute the code and catch the new traceback
+    try:
+        exec(code, globals, locals)
+    except:
+        exc_info = sys.exc_info()
+        new_tb = exc_info[2].tb_next
+
+    # return without this frame
+    return exc_info[:2] + (new_tb,)
+
+
+def _init_ugly_crap():
+    """This function implements a few ugly things so that we can patch the
+    traceback objects.  The function returned allows resetting `tb_next` on
+    any python traceback object.  Do not attempt to use this on non cpython
+    interpreters
+    """
+    import ctypes
+    from types import TracebackType
+
+    if PY2:
+        # figure out size of _Py_ssize_t for Python 2:
+        if hasattr(ctypes.pythonapi, 'Py_InitModule4_64'):
+            _Py_ssize_t = ctypes.c_int64
+        else:
+            _Py_ssize_t = ctypes.c_int
+    else:
+        # platform ssize_t on Python 3
+        _Py_ssize_t = ctypes.c_ssize_t
+
+    # regular python
+    class _PyObject(ctypes.Structure):
+        pass
+    _PyObject._fields_ = [
+        ('ob_refcnt', _Py_ssize_t),
+        ('ob_type', ctypes.POINTER(_PyObject))
+    ]
+
+    # python with trace
+    if hasattr(sys, 'getobjects'):
+        class _PyObject(ctypes.Structure):
+            pass
+        _PyObject._fields_ = [
+            ('_ob_next', ctypes.POINTER(_PyObject)),
+            ('_ob_prev', ctypes.POINTER(_PyObject)),
+            ('ob_refcnt', _Py_ssize_t),
+            ('ob_type', ctypes.POINTER(_PyObject))
+        ]
+
+    class _Traceback(_PyObject):
+        pass
+    _Traceback._fields_ = [
+        ('tb_next', ctypes.POINTER(_Traceback)),
+        ('tb_frame', ctypes.POINTER(_PyObject)),
+        ('tb_lasti', ctypes.c_int),
+        ('tb_lineno', ctypes.c_int)
+    ]
+
+    def tb_set_next(tb, next):
+        """Set the tb_next attribute of a traceback object."""
+        if not (isinstance(tb, TracebackType) and
+                (next is None or isinstance(next, TracebackType))):
+            raise TypeError('tb_set_next arguments must be traceback objects')
+        obj = _Traceback.from_address(id(tb))
+        if tb.tb_next is not None:
+            old = _Traceback.from_address(id(tb.tb_next))
+            old.ob_refcnt -= 1
+        if next is None:
+            obj.tb_next = ctypes.POINTER(_Traceback)()
+        else:
+            next = _Traceback.from_address(id(next))
+            next.ob_refcnt += 1
+            obj.tb_next = ctypes.pointer(next)
+
+    return tb_set_next
+
+
+# try to get a tb_set_next implementation if we don't have transparent
+# proxies.
+tb_set_next = None
+if tproxy is None:
+    try:
+        tb_set_next = _init_ugly_crap()
+    except:
+        pass
+    del _init_ugly_crap
diff --git a/python/jinja2/defaults.py b/python/jinja2/defaults.py
new file mode 100644
index 0000000..7c93dec
--- /dev/null
+++ b/python/jinja2/defaults.py
@@ -0,0 +1,56 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.defaults
+    ~~~~~~~~~~~~~~~
+
+    Jinja default filters and tags.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+from jinja2._compat import range_type
+from jinja2.utils import generate_lorem_ipsum, Cycler, Joiner, Namespace
+
+
+# defaults for the parser / lexer
+BLOCK_START_STRING = '{%'
+BLOCK_END_STRING = '%}'
+VARIABLE_START_STRING = '{{'
+VARIABLE_END_STRING = '}}'
+COMMENT_START_STRING = '{#'
+COMMENT_END_STRING = '#}'
+LINE_STATEMENT_PREFIX = None
+LINE_COMMENT_PREFIX = None
+TRIM_BLOCKS = False
+LSTRIP_BLOCKS = False
+NEWLINE_SEQUENCE = '\n'
+KEEP_TRAILING_NEWLINE = False
+
+
+# default filters, tests and namespace
+from jinja2.filters import FILTERS as DEFAULT_FILTERS
+from jinja2.tests import TESTS as DEFAULT_TESTS
+DEFAULT_NAMESPACE = {
+    'range':        range_type,
+    'dict':         dict,
+    'lipsum':       generate_lorem_ipsum,
+    'cycler':       Cycler,
+    'joiner':       Joiner,
+    'namespace':    Namespace
+}
+
+
+# default policies
+DEFAULT_POLICIES = {
+    'compiler.ascii_str':   True,
+    'urlize.rel':           'noopener',
+    'urlize.target':        None,
+    'truncate.leeway':      5,
+    'json.dumps_function':  None,
+    'json.dumps_kwargs':    {'sort_keys': True},
+    'ext.i18n.trimmed':     False,
+}
+
+
+# export all constants
+__all__ = tuple(x for x in locals().keys() if x.isupper())
diff --git a/python/jinja2/environment.py b/python/jinja2/environment.py
new file mode 100644
index 0000000..549d9af
--- /dev/null
+++ b/python/jinja2/environment.py
@@ -0,0 +1,1276 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.environment
+    ~~~~~~~~~~~~~~~~~~
+
+    Provides a class that holds runtime and parsing time options.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import os
+import sys
+import weakref
+from functools import reduce, partial
+from jinja2 import nodes
+from jinja2.defaults import BLOCK_START_STRING, \
+     BLOCK_END_STRING, VARIABLE_START_STRING, VARIABLE_END_STRING, \
+     COMMENT_START_STRING, COMMENT_END_STRING, LINE_STATEMENT_PREFIX, \
+     LINE_COMMENT_PREFIX, TRIM_BLOCKS, NEWLINE_SEQUENCE, \
+     DEFAULT_FILTERS, DEFAULT_TESTS, DEFAULT_NAMESPACE, \
+     DEFAULT_POLICIES, KEEP_TRAILING_NEWLINE, LSTRIP_BLOCKS
+from jinja2.lexer import get_lexer, TokenStream
+from jinja2.parser import Parser
+from jinja2.nodes import EvalContext
+from jinja2.compiler import generate, CodeGenerator
+from jinja2.runtime import Undefined, new_context, Context
+from jinja2.exceptions import TemplateSyntaxError, TemplateNotFound, \
+     TemplatesNotFound, TemplateRuntimeError
+from jinja2.utils import import_string, LRUCache, Markup, missing, \
+     concat, consume, internalcode, have_async_gen
+from jinja2._compat import imap, ifilter, string_types, iteritems, \
+     text_type, reraise, implements_iterator, implements_to_string, \
+     encode_filename, PY2, PYPY
+
+
+# for direct template usage we have up to ten living environments
+_spontaneous_environments = LRUCache(10)
+
+# the function to create jinja traceback objects.  This is dynamically
+# imported on the first exception in the exception handler.
+_make_traceback = None
+
+
+def get_spontaneous_environment(*args):
+    """Return a new spontaneous environment.  A spontaneous environment is an
+    unnamed and unaccessible (in theory) environment that is used for
+    templates generated from a string and not from the file system.
+    """
+    try:
+        env = _spontaneous_environments.get(args)
+    except TypeError:
+        return Environment(*args)
+    if env is not None:
+        return env
+    _spontaneous_environments[args] = env = Environment(*args)
+    env.shared = True
+    return env
+
+
+def create_cache(size):
+    """Return the cache class for the given size."""
+    if size == 0:
+        return None
+    if size < 0:
+        return {}
+    return LRUCache(size)
+
+
+def copy_cache(cache):
+    """Create an empty copy of the given cache."""
+    if cache is None:
+        return None
+    elif type(cache) is dict:
+        return {}
+    return LRUCache(cache.capacity)
+
+
+def load_extensions(environment, extensions):
+    """Load the extensions from the list and bind it to the environment.
+    Returns a dict of instantiated environments.
+    """
+    result = {}
+    for extension in extensions:
+        if isinstance(extension, string_types):
+            extension = import_string(extension)
+        result[extension.identifier] = extension(environment)
+    return result
+
+
+def fail_for_missing_callable(string, name):
+    msg = string % name
+    if isinstance(name, Undefined):
+        try:
+            name._fail_with_undefined_error()
+        except Exception as e:
+            msg = '%s (%s; did you forget to quote the callable name?)' % (msg, e)
+    raise TemplateRuntimeError(msg)
+
+
+def _environment_sanity_check(environment):
+    """Perform a sanity check on the environment."""
+    assert issubclass(environment.undefined, Undefined), 'undefined must ' \
+        'be a subclass of undefined because filters depend on it.'
+    assert environment.block_start_string != \
+        environment.variable_start_string != \
+        environment.comment_start_string, 'block, variable and comment ' \
+        'start strings must be different'
+    assert environment.newline_sequence in ('\r', '\r\n', '\n'), \
+        'newline_sequence set to unknown line ending string.'
+    return environment
+
+
+class Environment(object):
+    r"""The core component of Jinja is the `Environment`.  It contains
+    important shared variables like configuration, filters, tests,
+    globals and others.  Instances of this class may be modified if
+    they are not shared and if no template was loaded so far.
+    Modifications on environments after the first template was loaded
+    will lead to surprising effects and undefined behavior.
+
+    Here are the possible initialization parameters:
+
+        `block_start_string`
+            The string marking the beginning of a block.  Defaults to ``'{%'``.
+
+        `block_end_string`
+            The string marking the end of a block.  Defaults to ``'%}'``.
+
+        `variable_start_string`
+            The string marking the beginning of a print statement.
+            Defaults to ``'{{'``.
+
+        `variable_end_string`
+            The string marking the end of a print statement.  Defaults to
+            ``'}}'``.
+
+        `comment_start_string`
+            The string marking the beginning of a comment.  Defaults to ``'{#'``.
+
+        `comment_end_string`
+            The string marking the end of a comment.  Defaults to ``'#}'``.
+
+        `line_statement_prefix`
+            If given and a string, this will be used as prefix for line based
+            statements.  See also :ref:`line-statements`.
+
+        `line_comment_prefix`
+            If given and a string, this will be used as prefix for line based
+            comments.  See also :ref:`line-statements`.
+
+            .. versionadded:: 2.2
+
+        `trim_blocks`
+            If this is set to ``True`` the first newline after a block is
+            removed (block, not variable tag!).  Defaults to `False`.
+
+        `lstrip_blocks`
+            If this is set to ``True`` leading spaces and tabs are stripped
+            from the start of a line to a block.  Defaults to `False`.
+
+        `newline_sequence`
+            The sequence that starts a newline.  Must be one of ``'\r'``,
+            ``'\n'`` or ``'\r\n'``.  The default is ``'\n'`` which is a
+            useful default for Linux and OS X systems as well as web
+            applications.
+
+        `keep_trailing_newline`
+            Preserve the trailing newline when rendering templates.
+            The default is ``False``, which causes a single newline,
+            if present, to be stripped from the end of the template.
+
+            .. versionadded:: 2.7
+
+        `extensions`
+            List of Jinja extensions to use.  This can either be import paths
+            as strings or extension classes.  For more information have a
+            look at :ref:`the extensions documentation <jinja-extensions>`.
+
+        `optimized`
+            should the optimizer be enabled?  Default is ``True``.
+
+        `undefined`
+            :class:`Undefined` or a subclass of it that is used to represent
+            undefined values in the template.
+
+        `finalize`
+            A callable that can be used to process the result of a variable
+            expression before it is output.  For example one can convert
+            ``None`` implicitly into an empty string here.
+
+        `autoescape`
+            If set to ``True`` the XML/HTML autoescaping feature is enabled by
+            default.  For more details about autoescaping see
+            :class:`~jinja2.utils.Markup`.  As of Jinja 2.4 this can also
+            be a callable that is passed the template name and has to
+            return ``True`` or ``False`` depending on autoescape should be
+            enabled by default.
+
+            .. versionchanged:: 2.4
+               `autoescape` can now be a function
+
+        `loader`
+            The template loader for this environment.
+
+        `cache_size`
+            The size of the cache.  Per default this is ``400`` which means
+            that if more than 400 templates are loaded the loader will clean
+            out the least recently used template.  If the cache size is set to
+            ``0`` templates are recompiled all the time, if the cache size is
+            ``-1`` the cache will not be cleaned.
+
+            .. versionchanged:: 2.8
+               The cache size was increased to 400 from a low 50.
+
+        `auto_reload`
+            Some loaders load templates from locations where the template
+            sources may change (ie: file system or database).  If
+            ``auto_reload`` is set to ``True`` (default) every time a template is
+            requested the loader checks if the source changed and if yes, it
+            will reload the template.  For higher performance it's possible to
+            disable that.
+
+        `bytecode_cache`
+            If set to a bytecode cache object, this object will provide a
+            cache for the internal Jinja bytecode so that templates don't
+            have to be parsed if they were not changed.
+
+            See :ref:`bytecode-cache` for more information.
+
+        `enable_async`
+            If set to true this enables async template execution which allows
+            you to take advantage of newer Python features.  This requires
+            Python 3.6 or later.
+    """
+
+    #: if this environment is sandboxed.  Modifying this variable won't make
+    #: the environment sandboxed though.  For a real sandboxed environment
+    #: have a look at jinja2.sandbox.  This flag alone controls the code
+    #: generation by the compiler.
+    sandboxed = False
+
+    #: True if the environment is just an overlay
+    overlayed = False
+
+    #: the environment this environment is linked to if it is an overlay
+    linked_to = None
+
+    #: shared environments have this set to `True`.  A shared environment
+    #: must not be modified
+    shared = False
+
+    #: these are currently EXPERIMENTAL undocumented features.
+    exception_handler = None
+    exception_formatter = None
+
+    #: the class that is used for code generation.  See
+    #: :class:`~jinja2.compiler.CodeGenerator` for more information.
+    code_generator_class = CodeGenerator
+
+    #: the context class thatis used for templates.  See
+    #: :class:`~jinja2.runtime.Context` for more information.
+    context_class = Context
+
+    def __init__(self,
+                 block_start_string=BLOCK_START_STRING,
+                 block_end_string=BLOCK_END_STRING,
+                 variable_start_string=VARIABLE_START_STRING,
+                 variable_end_string=VARIABLE_END_STRING,
+                 comment_start_string=COMMENT_START_STRING,
+                 comment_end_string=COMMENT_END_STRING,
+                 line_statement_prefix=LINE_STATEMENT_PREFIX,
+                 line_comment_prefix=LINE_COMMENT_PREFIX,
+                 trim_blocks=TRIM_BLOCKS,
+                 lstrip_blocks=LSTRIP_BLOCKS,
+                 newline_sequence=NEWLINE_SEQUENCE,
+                 keep_trailing_newline=KEEP_TRAILING_NEWLINE,
+                 extensions=(),
+                 optimized=True,
+                 undefined=Undefined,
+                 finalize=None,
+                 autoescape=False,
+                 loader=None,
+                 cache_size=400,
+                 auto_reload=True,
+                 bytecode_cache=None,
+                 enable_async=False):
+        # !!Important notice!!
+        #   The constructor accepts quite a few arguments that should be
+        #   passed by keyword rather than position.  However it's important to
+        #   not change the order of arguments because it's used at least
+        #   internally in those cases:
+        #       -   spontaneous environments (i18n extension and Template)
+        #       -   unittests
+        #   If parameter changes are required only add parameters at the end
+        #   and don't change the arguments (or the defaults!) of the arguments
+        #   existing already.
+
+        # lexer / parser information
+        self.block_start_string = block_start_string
+        self.block_end_string = block_end_string
+        self.variable_start_string = variable_start_string
+        self.variable_end_string = variable_end_string
+        self.comment_start_string = comment_start_string
+        self.comment_end_string = comment_end_string
+        self.line_statement_prefix = line_statement_prefix
+        self.line_comment_prefix = line_comment_prefix
+        self.trim_blocks = trim_blocks
+        self.lstrip_blocks = lstrip_blocks
+        self.newline_sequence = newline_sequence
+        self.keep_trailing_newline = keep_trailing_newline
+
+        # runtime information
+        self.undefined = undefined
+        self.optimized = optimized
+        self.finalize = finalize
+        self.autoescape = autoescape
+
+        # defaults
+        self.filters = DEFAULT_FILTERS.copy()
+        self.tests = DEFAULT_TESTS.copy()
+        self.globals = DEFAULT_NAMESPACE.copy()
+
+        # set the loader provided
+        self.loader = loader
+        self.cache = create_cache(cache_size)
+        self.bytecode_cache = bytecode_cache
+        self.auto_reload = auto_reload
+
+        # configurable policies
+        self.policies = DEFAULT_POLICIES.copy()
+
+        # load extensions
+        self.extensions = load_extensions(self, extensions)
+
+        self.enable_async = enable_async
+        self.is_async = self.enable_async and have_async_gen
+
+        _environment_sanity_check(self)
+
+    def add_extension(self, extension):
+        """Adds an extension after the environment was created.
+
+        .. versionadded:: 2.5
+        """
+        self.extensions.update(load_extensions(self, [extension]))
+
+    def extend(self, **attributes):
+        """Add the items to the instance of the environment if they do not exist
+        yet.  This is used by :ref:`extensions <writing-extensions>` to register
+        callbacks and configuration values without breaking inheritance.
+        """
+        for key, value in iteritems(attributes):
+            if not hasattr(self, key):
+                setattr(self, key, value)
+
+    def overlay(self, block_start_string=missing, block_end_string=missing,
+                variable_start_string=missing, variable_end_string=missing,
+                comment_start_string=missing, comment_end_string=missing,
+                line_statement_prefix=missing, line_comment_prefix=missing,
+                trim_blocks=missing, lstrip_blocks=missing,
+                extensions=missing, optimized=missing,
+                undefined=missing, finalize=missing, autoescape=missing,
+                loader=missing, cache_size=missing, auto_reload=missing,
+                bytecode_cache=missing):
+        """Create a new overlay environment that shares all the data with the
+        current environment except for cache and the overridden attributes.
+        Extensions cannot be removed for an overlayed environment.  An overlayed
+        environment automatically gets all the extensions of the environment it
+        is linked to plus optional extra extensions.
+
+        Creating overlays should happen after the initial environment was set
+        up completely.  Not all attributes are truly linked, some are just
+        copied over so modifications on the original environment may not shine
+        through.
+        """
+        args = dict(locals())
+        del args['self'], args['cache_size'], args['extensions']
+
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.overlayed = True
+        rv.linked_to = self
+
+        for key, value in iteritems(args):
+            if value is not missing:
+                setattr(rv, key, value)
+
+        if cache_size is not missing:
+            rv.cache = create_cache(cache_size)
+        else:
+            rv.cache = copy_cache(self.cache)
+
+        rv.extensions = {}
+        for key, value in iteritems(self.extensions):
+            rv.extensions[key] = value.bind(rv)
+        if extensions is not missing:
+            rv.extensions.update(load_extensions(rv, extensions))
+
+        return _environment_sanity_check(rv)
+
+    lexer = property(get_lexer, doc="The lexer for this environment.")
+
+    def iter_extensions(self):
+        """Iterates over the extensions by priority."""
+        return iter(sorted(self.extensions.values(),
+                           key=lambda x: x.priority))
+
+    def getitem(self, obj, argument):
+        """Get an item or attribute of an object but prefer the item."""
+        try:
+            return obj[argument]
+        except (AttributeError, TypeError, LookupError):
+            if isinstance(argument, string_types):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        return getattr(obj, attr)
+                    except AttributeError:
+                        pass
+            return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj, attribute):
+        """Get an item or attribute of an object but prefer the attribute.
+        Unlike :meth:`getitem` the attribute *must* be a bytestring.
+        """
+        try:
+            return getattr(obj, attribute)
+        except AttributeError:
+            pass
+        try:
+            return obj[attribute]
+        except (TypeError, LookupError, AttributeError):
+            return self.undefined(obj=obj, name=attribute)
+
+    def call_filter(self, name, value, args=None, kwargs=None,
+                    context=None, eval_ctx=None):
+        """Invokes a filter on a value the same way the compiler does it.
+
+        Note that on Python 3 this might return a coroutine in case the
+        filter is running from an environment in async mode and the filter
+        supports async execution.  It's your responsibility to await this
+        if needed.
+
+        .. versionadded:: 2.7
+        """
+        func = self.filters.get(name)
+        if func is None:
+            fail_for_missing_callable('no filter named %r', name)
+        args = [value] + list(args or ())
+        if getattr(func, 'contextfilter', False):
+            if context is None:
+                raise TemplateRuntimeError('Attempted to invoke context '
+                                           'filter without context')
+            args.insert(0, context)
+        elif getattr(func, 'evalcontextfilter', False):
+            if eval_ctx is None:
+                if context is not None:
+                    eval_ctx = context.eval_ctx
+                else:
+                    eval_ctx = EvalContext(self)
+            args.insert(0, eval_ctx)
+        elif getattr(func, 'environmentfilter', False):
+            args.insert(0, self)
+        return func(*args, **(kwargs or {}))
+
+    def call_test(self, name, value, args=None, kwargs=None):
+        """Invokes a test on a value the same way the compiler does it.
+
+        .. versionadded:: 2.7
+        """
+        func = self.tests.get(name)
+        if func is None:
+            fail_for_missing_callable('no test named %r', name)
+        return func(value, *(args or ()), **(kwargs or {}))
+
+    @internalcode
+    def parse(self, source, name=None, filename=None):
+        """Parse the sourcecode and return the abstract syntax tree.  This
+        tree of nodes is used by the compiler to convert the template into
+        executable source- or bytecode.  This is useful for debugging or to
+        extract information from templates.
+
+        If you are :ref:`developing Jinja2 extensions <writing-extensions>`
+        this gives you a good overview of the node tree generated.
+        """
+        try:
+            return self._parse(source, name, filename)
+        except TemplateSyntaxError:
+            exc_info = sys.exc_info()
+        self.handle_exception(exc_info, source_hint=source)
+
+    def _parse(self, source, name, filename):
+        """Internal parsing function used by `parse` and `compile`."""
+        return Parser(self, source, name, encode_filename(filename)).parse()
+
+    def lex(self, source, name=None, filename=None):
+        """Lex the given sourcecode and return a generator that yields
+        tokens as tuples in the form ``(lineno, token_type, value)``.
+        This can be useful for :ref:`extension development <writing-extensions>`
+        and debugging templates.
+
+        This does not perform preprocessing.  If you want the preprocessing
+        of the extensions to be applied you have to filter source through
+        the :meth:`preprocess` method.
+        """
+        source = text_type(source)
+        try:
+            return self.lexer.tokeniter(source, name, filename)
+        except TemplateSyntaxError:
+            exc_info = sys.exc_info()
+        self.handle_exception(exc_info, source_hint=source)
+
+    def preprocess(self, source, name=None, filename=None):
+        """Preprocesses the source with all extensions.  This is automatically
+        called for all parsing and compiling methods but *not* for :meth:`lex`
+        because there you usually only want the actual source tokenized.
+        """
+        return reduce(lambda s, e: e.preprocess(s, name, filename),
+                      self.iter_extensions(), text_type(source))
+
+    def _tokenize(self, source, name, filename=None, state=None):
+        """Called by the parser to do the preprocessing and filtering
+        for all the extensions.  Returns a :class:`~jinja2.lexer.TokenStream`.
+        """
+        source = self.preprocess(source, name, filename)
+        stream = self.lexer.tokenize(source, name, filename, state)
+        for ext in self.iter_extensions():
+            stream = ext.filter_stream(stream)
+            if not isinstance(stream, TokenStream):
+                stream = TokenStream(stream, name, filename)
+        return stream
+
+    def _generate(self, source, name, filename, defer_init=False):
+        """Internal hook that can be overridden to hook a different generate
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return generate(source, self, name, filename, defer_init=defer_init,
+                        optimized=self.optimized)
+
+    def _compile(self, source, filename):
+        """Internal hook that can be overridden to hook a different compile
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return compile(source, filename, 'exec')
+
+    @internalcode
+    def compile(self, source, name=None, filename=None, raw=False,
+                defer_init=False):
+        """Compile a node or template source code.  The `name` parameter is
+        the load name of the template after it was joined using
+        :meth:`join_path` if necessary, not the filename on the file system.
+        the `filename` parameter is the estimated filename of the template on
+        the file system.  If the template came from a database or memory this
+        can be omitted.
+
+        The return value of this method is a python code object.  If the `raw`
+        parameter is `True` the return value will be a string with python
+        code equivalent to the bytecode returned otherwise.  This method is
+        mainly used internally.
+
+        `defer_init` is use internally to aid the module code generator.  This
+        causes the generated code to be able to import without the global
+        environment variable to be set.
+
+        .. versionadded:: 2.4
+           `defer_init` parameter added.
+        """
+        source_hint = None
+        try:
+            if isinstance(source, string_types):
+                source_hint = source
+                source = self._parse(source, name, filename)
+            source = self._generate(source, name, filename,
+                                    defer_init=defer_init)
+            if raw:
+                return source
+            if filename is None:
+                filename = '<template>'
+            else:
+                filename = encode_filename(filename)
+            return self._compile(source, filename)
+        except TemplateSyntaxError:
+            exc_info = sys.exc_info()
+        self.handle_exception(exc_info, source_hint=source_hint)
+
+    def compile_expression(self, source, undefined_to_none=True):
+        """A handy helper method that returns a callable that accepts keyword
+        arguments that appear as variables in the expression.  If called it
+        returns the result of the expression.
+
+        This is useful if applications want to use the same rules as Jinja
+        in template "configuration files" or similar situations.
+
+        Example usage:
+
+        >>> env = Environment()
+        >>> expr = env.compile_expression('foo == 42')
+        >>> expr(foo=23)
+        False
+        >>> expr(foo=42)
+        True
+
+        Per default the return value is converted to `None` if the
+        expression returns an undefined value.  This can be changed
+        by setting `undefined_to_none` to `False`.
+
+        >>> env.compile_expression('var')() is None
+        True
+        >>> env.compile_expression('var', undefined_to_none=False)()
+        Undefined
+
+        .. versionadded:: 2.1
+        """
+        parser = Parser(self, source, state='variable')
+        exc_info = None
+        try:
+            expr = parser.parse_expression()
+            if not parser.stream.eos:
+                raise TemplateSyntaxError('chunk after expression',
+                                          parser.stream.current.lineno,
+                                          None, None)
+            expr.set_environment(self)
+        except TemplateSyntaxError:
+            exc_info = sys.exc_info()
+        if exc_info is not None:
+            self.handle_exception(exc_info, source_hint=source)
+        body = [nodes.Assign(nodes.Name('result', 'store'), expr, lineno=1)]
+        template = self.from_string(nodes.Template(body, lineno=1))
+        return TemplateExpression(template, undefined_to_none)
+
+    def compile_templates(self, target, extensions=None, filter_func=None,
+                          zip='deflated', log_function=None,
+                          ignore_errors=True, py_compile=False):
+        """Finds all the templates the loader can find, compiles them
+        and stores them in `target`.  If `zip` is `None`, instead of in a
+        zipfile, the templates will be stored in a directory.
+        By default a deflate zip algorithm is used. To switch to
+        the stored algorithm, `zip` can be set to ``'stored'``.
+
+        `extensions` and `filter_func` are passed to :meth:`list_templates`.
+        Each template returned will be compiled to the target folder or
+        zipfile.
+
+        By default template compilation errors are ignored.  In case a
+        log function is provided, errors are logged.  If you want template
+        syntax errors to abort the compilation you can set `ignore_errors`
+        to `False` and you will get an exception on syntax errors.
+
+        If `py_compile` is set to `True` .pyc files will be written to the
+        target instead of standard .py files.  This flag does not do anything
+        on pypy and Python 3 where pyc files are not picked up by itself and
+        don't give much benefit.
+
+        .. versionadded:: 2.4
+        """
+        from jinja2.loaders import ModuleLoader
+
+        if log_function is None:
+            log_function = lambda x: None
+
+        if py_compile:
+            if not PY2 or PYPY:
+                from warnings import warn
+                warn(Warning('py_compile has no effect on pypy or Python 3'))
+                py_compile = False
+            else:
+                import imp
+                import marshal
+                py_header = imp.get_magic() + \
+                    u'\xff\xff\xff\xff'.encode('iso-8859-15')
+
+                # Python 3.3 added a source filesize to the header
+                if sys.version_info >= (3, 3):
+                    py_header += u'\x00\x00\x00\x00'.encode('iso-8859-15')
+
+        def write_file(filename, data, mode):
+            if zip:
+                info = ZipInfo(filename)
+                info.external_attr = 0o755 << 16
+                zip_file.writestr(info, data)
+            else:
+                f = open(os.path.join(target, filename), mode)
+                try:
+                    f.write(data)
+                finally:
+                    f.close()
+
+        if zip is not None:
+            from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED
+            zip_file = ZipFile(target, 'w', dict(deflated=ZIP_DEFLATED,
+                                                 stored=ZIP_STORED)[zip])
+            log_function('Compiling into Zip archive "%s"' % target)
+        else:
+            if not os.path.isdir(target):
+                os.makedirs(target)
+            log_function('Compiling into folder "%s"' % target)
+
+        try:
+            for name in self.list_templates(extensions, filter_func):
+                source, filename, _ = self.loader.get_source(self, name)
+                try:
+                    code = self.compile(source, name, filename, True, True)
+                except TemplateSyntaxError as e:
+                    if not ignore_errors:
+                        raise
+                    log_function('Could not compile "%s": %s' % (name, e))
+                    continue
+
+                filename = ModuleLoader.get_module_filename(name)
+
+                if py_compile:
+                    c = self._compile(code, encode_filename(filename))
+                    write_file(filename + 'c', py_header +
+                               marshal.dumps(c), 'wb')
+                    log_function('Byte-compiled "%s" as %s' %
+                                 (name, filename + 'c'))
+                else:
+                    write_file(filename, code, 'w')
+                    log_function('Compiled "%s" as %s' % (name, filename))
+        finally:
+            if zip:
+                zip_file.close()
+
+        log_function('Finished compiling templates')
+
+    def list_templates(self, extensions=None, filter_func=None):
+        """Returns a list of templates for this environment.  This requires
+        that the loader supports the loader's
+        :meth:`~BaseLoader.list_templates` method.
+
+        If there are other files in the template folder besides the
+        actual templates, the returned list can be filtered.  There are two
+        ways: either `extensions` is set to a list of file extensions for
+        templates, or a `filter_func` can be provided which is a callable that
+        is passed a template name and should return `True` if it should end up
+        in the result list.
+
+        If the loader does not support that, a :exc:`TypeError` is raised.
+
+        .. versionadded:: 2.4
+        """
+        x = self.loader.list_templates()
+        if extensions is not None:
+            if filter_func is not None:
+                raise TypeError('either extensions or filter_func '
+                                'can be passed, but not both')
+            filter_func = lambda x: '.' in x and \
+                                    x.rsplit('.', 1)[1] in extensions
+        if filter_func is not None:
+            x = list(ifilter(filter_func, x))
+        return x
+
+    def handle_exception(self, exc_info=None, rendered=False, source_hint=None):
+        """Exception handling helper.  This is used internally to either raise
+        rewritten exceptions or return a rendered traceback for the template.
+        """
+        global _make_traceback
+        if exc_info is None:
+            exc_info = sys.exc_info()
+
+        # the debugging module is imported when it's used for the first time.
+        # we're doing a lot of stuff there and for applications that do not
+        # get any exceptions in template rendering there is no need to load
+        # all of that.
+        if _make_traceback is None:
+            from jinja2.debug import make_traceback as _make_traceback
+        traceback = _make_traceback(exc_info, source_hint)
+        if rendered and self.exception_formatter is not None:
+            return self.exception_formatter(traceback)
+        if self.exception_handler is not None:
+            self.exception_handler(traceback)
+        exc_type, exc_value, tb = traceback.standard_exc_info
+        reraise(exc_type, exc_value, tb)
+
+    def join_path(self, template, parent):
+        """Join a template with the parent.  By default all the lookups are
+        relative to the loader root so this method returns the `template`
+        parameter unchanged, but if the paths should be relative to the
+        parent template, this function can be used to calculate the real
+        template name.
+
+        Subclasses may override this method and implement template path
+        joining here.
+        """
+        return template
+
+    @internalcode
+    def _load_template(self, name, globals):
+        if self.loader is None:
+            raise TypeError('no loader for this environment specified')
+        cache_key = (weakref.ref(self.loader), name)
+        if self.cache is not None:
+            template = self.cache.get(cache_key)
+            if template is not None and (not self.auto_reload or
+                                         template.is_up_to_date):
+                return template
+        template = self.loader.load(self, name, globals)
+        if self.cache is not None:
+            self.cache[cache_key] = template
+        return template
+
+    @internalcode
+    def get_template(self, name, parent=None, globals=None):
+        """Load a template from the loader.  If a loader is configured this
+        method asks the loader for the template and returns a :class:`Template`.
+        If the `parent` parameter is not `None`, :meth:`join_path` is called
+        to get the real template name before loading.
+
+        The `globals` parameter can be used to provide template wide globals.
+        These variables are available in the context at render time.
+
+        If the template does not exist a :exc:`TemplateNotFound` exception is
+        raised.
+
+        .. versionchanged:: 2.4
+           If `name` is a :class:`Template` object it is returned from the
+           function unchanged.
+        """
+        if isinstance(name, Template):
+            return name
+        if parent is not None:
+            name = self.join_path(name, parent)
+        return self._load_template(name, self.make_globals(globals))
+
+    @internalcode
+    def select_template(self, names, parent=None, globals=None):
+        """Works like :meth:`get_template` but tries a number of templates
+        before it fails.  If it cannot find any of the templates, it will
+        raise a :exc:`TemplatesNotFound` exception.
+
+        .. versionadded:: 2.3
+
+        .. versionchanged:: 2.4
+           If `names` contains a :class:`Template` object it is returned
+           from the function unchanged.
+        """
+        if not names:
+            raise TemplatesNotFound(message=u'Tried to select from an empty list '
+                                            u'of templates.')
+        globals = self.make_globals(globals)
+        for name in names:
+            if isinstance(name, Template):
+                return name
+            if parent is not None:
+                name = self.join_path(name, parent)
+            try:
+                return self._load_template(name, globals)
+            except TemplateNotFound:
+                pass
+        raise TemplatesNotFound(names)
+
+    @internalcode
+    def get_or_select_template(self, template_name_or_list,
+                               parent=None, globals=None):
+        """Does a typecheck and dispatches to :meth:`select_template`
+        if an iterable of template names is given, otherwise to
+        :meth:`get_template`.
+
+        .. versionadded:: 2.3
+        """
+        if isinstance(template_name_or_list, string_types):
+            return self.get_template(template_name_or_list, parent, globals)
+        elif isinstance(template_name_or_list, Template):
+            return template_name_or_list
+        return self.select_template(template_name_or_list, parent, globals)
+
+    def from_string(self, source, globals=None, template_class=None):
+        """Load a template from a string.  This parses the source given and
+        returns a :class:`Template` object.
+        """
+        globals = self.make_globals(globals)
+        cls = template_class or self.template_class
+        return cls.from_code(self, self.compile(source), globals, None)
+
+    def make_globals(self, d):
+        """Return a dict for the globals."""
+        if not d:
+            return self.globals
+        return dict(self.globals, **d)
+
+
+class Template(object):
+    """The central template object.  This class represents a compiled template
+    and is used to evaluate it.
+
+    Normally the template object is generated from an :class:`Environment` but
+    it also has a constructor that makes it possible to create a template
+    instance directly using the constructor.  It takes the same arguments as
+    the environment constructor but it's not possible to specify a loader.
+
+    Every template object has a few methods and members that are guaranteed
+    to exist.  However it's important that a template object should be
+    considered immutable.  Modifications on the object are not supported.
+
+    Template objects created from the constructor rather than an environment
+    do have an `environment` attribute that points to a temporary environment
+    that is probably shared with other templates created with the constructor
+    and compatible settings.
+
+    >>> template = Template('Hello {{ name }}!')
+    >>> template.render(name='John Doe') == u'Hello John Doe!'
+    True
+    >>> stream = template.stream(name='John Doe')
+    >>> next(stream) == u'Hello John Doe!'
+    True
+    >>> next(stream)
+    Traceback (most recent call last):
+        ...
+    StopIteration
+    """
+
+    def __new__(cls, source,
+                block_start_string=BLOCK_START_STRING,
+                block_end_string=BLOCK_END_STRING,
+                variable_start_string=VARIABLE_START_STRING,
+                variable_end_string=VARIABLE_END_STRING,
+                comment_start_string=COMMENT_START_STRING,
+                comment_end_string=COMMENT_END_STRING,
+                line_statement_prefix=LINE_STATEMENT_PREFIX,
+                line_comment_prefix=LINE_COMMENT_PREFIX,
+                trim_blocks=TRIM_BLOCKS,
+                lstrip_blocks=LSTRIP_BLOCKS,
+                newline_sequence=NEWLINE_SEQUENCE,
+                keep_trailing_newline=KEEP_TRAILING_NEWLINE,
+                extensions=(),
+                optimized=True,
+                undefined=Undefined,
+                finalize=None,
+                autoescape=False,
+                enable_async=False):
+        env = get_spontaneous_environment(
+            block_start_string, block_end_string, variable_start_string,
+            variable_end_string, comment_start_string, comment_end_string,
+            line_statement_prefix, line_comment_prefix, trim_blocks,
+            lstrip_blocks, newline_sequence, keep_trailing_newline,
+            frozenset(extensions), optimized, undefined, finalize, autoescape,
+            None, 0, False, None, enable_async)
+        return env.from_string(source, template_class=cls)
+
+    @classmethod
+    def from_code(cls, environment, code, globals, uptodate=None):
+        """Creates a template object from compiled code and the globals.  This
+        is used by the loaders and environment to create a template object.
+        """
+        namespace = {
+            'environment':  environment,
+            '__file__':     code.co_filename
+        }
+        exec(code, namespace)
+        rv = cls._from_namespace(environment, namespace, globals)
+        rv._uptodate = uptodate
+        return rv
+
+    @classmethod
+    def from_module_dict(cls, environment, module_dict, globals):
+        """Creates a template object from a module.  This is used by the
+        module loader to create a template object.
+
+        .. versionadded:: 2.4
+        """
+        return cls._from_namespace(environment, module_dict, globals)
+
+    @classmethod
+    def _from_namespace(cls, environment, namespace, globals):
+        t = object.__new__(cls)
+        t.environment = environment
+        t.globals = globals
+        t.name = namespace['name']
+        t.filename = namespace['__file__']
+        t.blocks = namespace['blocks']
+
+        # render function and module
+        t.root_render_func = namespace['root']
+        t._module = None
+
+        # debug and loader helpers
+        t._debug_info = namespace['debug_info']
+        t._uptodate = None
+
+        # store the reference
+        namespace['environment'] = environment
+        namespace['__jinja_template__'] = t
+
+        return t
+
+    def render(self, *args, **kwargs):
+        """This method accepts the same arguments as the `dict` constructor:
+        A dict, a dict subclass or some keyword arguments.  If no arguments
+        are given the context will be empty.  These two calls do the same::
+
+            template.render(knights='that say nih')
+            template.render({'knights': 'that say nih'})
+
+        This will return the rendered template as unicode string.
+        """
+        vars = dict(*args, **kwargs)
+        try:
+            return concat(self.root_render_func(self.new_context(vars)))
+        except Exception:
+            exc_info = sys.exc_info()
+        return self.environment.handle_exception(exc_info, True)
+
+    def render_async(self, *args, **kwargs):
+        """This works similar to :meth:`render` but returns a coroutine
+        that when awaited returns the entire rendered template string.  This
+        requires the async feature to be enabled.
+
+        Example usage::
+
+            await template.render_async(knights='that say nih; asynchronously')
+        """
+        # see asyncsupport for the actual implementation
+        raise NotImplementedError('This feature is not available for this '
+                                  'version of Python')
+
+    def stream(self, *args, **kwargs):
+        """Works exactly like :meth:`generate` but returns a
+        :class:`TemplateStream`.
+        """
+        return TemplateStream(self.generate(*args, **kwargs))
+
+    def generate(self, *args, **kwargs):
+        """For very large templates it can be useful to not render the whole
+        template at once but evaluate each statement after another and yield
+        piece for piece.  This method basically does exactly that and returns
+        a generator that yields one item after another as unicode strings.
+
+        It accepts the same arguments as :meth:`render`.
+        """
+        vars = dict(*args, **kwargs)
+        try:
+            for event in self.root_render_func(self.new_context(vars)):
+                yield event
+        except Exception:
+            exc_info = sys.exc_info()
+        else:
+            return
+        yield self.environment.handle_exception(exc_info, True)
+
+    def generate_async(self, *args, **kwargs):
+        """An async version of :meth:`generate`.  Works very similarly but
+        returns an async iterator instead.
+        """
+        # see asyncsupport for the actual implementation
+        raise NotImplementedError('This feature is not available for this '
+                                  'version of Python')
+
+    def new_context(self, vars=None, shared=False, locals=None):
+        """Create a new :class:`Context` for this template.  The vars
+        provided will be passed to the template.  Per default the globals
+        are added to the context.  If shared is set to `True` the data
+        is passed as it to the context without adding the globals.
+
+        `locals` can be a dict of local variables for internal usage.
+        """
+        return new_context(self.environment, self.name, self.blocks,
+                           vars, shared, self.globals, locals)
+
+    def make_module(self, vars=None, shared=False, locals=None):
+        """This method works like the :attr:`module` attribute when called
+        without arguments but it will evaluate the template on every call
+        rather than caching it.  It's also possible to provide
+        a dict which is then used as context.  The arguments are the same
+        as for the :meth:`new_context` method.
+        """
+        return TemplateModule(self, self.new_context(vars, shared, locals))
+
+    def make_module_async(self, vars=None, shared=False, locals=None):
+        """As template module creation can invoke template code for
+        asynchronous exections this method must be used instead of the
+        normal :meth:`make_module` one.  Likewise the module attribute
+        becomes unavailable in async mode.
+        """
+        # see asyncsupport for the actual implementation
+        raise NotImplementedError('This feature is not available for this '
+                                  'version of Python')
+
+    @internalcode
+    def _get_default_module(self):
+        if self._module is not None:
+            return self._module
+        self._module = rv = self.make_module()
+        return rv
+
+    @property
+    def module(self):
+        """The template as module.  This is used for imports in the
+        template runtime but is also useful if one wants to access
+        exported template variables from the Python layer:
+
+        >>> t = Template('{% macro foo() %}42{% endmacro %}23')
+        >>> str(t.module)
+        '23'
+        >>> t.module.foo() == u'42'
+        True
+
+        This attribute is not available if async mode is enabled.
+        """
+        return self._get_default_module()
+
+    def get_corresponding_lineno(self, lineno):
+        """Return the source line number of a line number in the
+        generated bytecode as they are not in sync.
+        """
+        for template_line, code_line in reversed(self.debug_info):
+            if code_line <= lineno:
+                return template_line
+        return 1
+
+    @property
+    def is_up_to_date(self):
+        """If this variable is `False` there is a newer version available."""
+        if self._uptodate is None:
+            return True
+        return self._uptodate()
+
+    @property
+    def debug_info(self):
+        """The debug info mapping."""
+        return [tuple(imap(int, x.split('='))) for x in
+                self._debug_info.split('&')]
+
+    def __repr__(self):
+        if self.name is None:
+            name = 'memory:%x' % id(self)
+        else:
+            name = repr(self.name)
+        return '<%s %s>' % (self.__class__.__name__, name)
+
+
+@implements_to_string
+class TemplateModule(object):
+    """Represents an imported template.  All the exported names of the
+    template are available as attributes on this object.  Additionally
+    converting it into an unicode- or bytestrings renders the contents.
+    """
+
+    def __init__(self, template, context, body_stream=None):
+        if body_stream is None:
+            if context.environment.is_async:
+                raise RuntimeError('Async mode requires a body stream '
+                                   'to be passed to a template module.  Use '
+                                   'the async methods of the API you are '
+                                   'using.')
+            body_stream = list(template.root_render_func(context))
+        self._body_stream = body_stream
+        self.__dict__.update(context.get_exported())
+        self.__name__ = template.name
+
+    def __html__(self):
+        return Markup(concat(self._body_stream))
+
+    def __str__(self):
+        return concat(self._body_stream)
+
+    def __repr__(self):
+        if self.__name__ is None:
+            name = 'memory:%x' % id(self)
+        else:
+            name = repr(self.__name__)
+        return '<%s %s>' % (self.__class__.__name__, name)
+
+
+class TemplateExpression(object):
+    """The :meth:`jinja2.Environment.compile_expression` method returns an
+    instance of this object.  It encapsulates the expression-like access
+    to the template with an expression it wraps.
+    """
+
+    def __init__(self, template, undefined_to_none):
+        self._template = template
+        self._undefined_to_none = undefined_to_none
+
+    def __call__(self, *args, **kwargs):
+        context = self._template.new_context(dict(*args, **kwargs))
+        consume(self._template.root_render_func(context))
+        rv = context.vars['result']
+        if self._undefined_to_none and isinstance(rv, Undefined):
+            rv = None
+        return rv
+
+
+@implements_iterator
+class TemplateStream(object):
+    """A template stream works pretty much like an ordinary python generator
+    but it can buffer multiple items to reduce the number of total iterations.
+    Per default the output is unbuffered which means that for every unbuffered
+    instruction in the template one unicode string is yielded.
+
+    If buffering is enabled with a buffer size of 5, five items are combined
+    into a new unicode string.  This is mainly useful if you are streaming
+    big templates to a client via WSGI which flushes after each iteration.
+    """
+
+    def __init__(self, gen):
+        self._gen = gen
+        self.disable_buffering()
+
+    def dump(self, fp, encoding=None, errors='strict'):
+        """Dump the complete stream into a file or file-like object.
+        Per default unicode strings are written, if you want to encode
+        before writing specify an `encoding`.
+
+        Example usage::
+
+            Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
+        """
+        close = False
+        if isinstance(fp, string_types):
+            if encoding is None:
+                encoding = 'utf-8'
+            fp = open(fp, 'wb')
+            close = True
+        try:
+            if encoding is not None:
+                iterable = (x.encode(encoding, errors) for x in self)
+            else:
+                iterable = self
+            if hasattr(fp, 'writelines'):
+                fp.writelines(iterable)
+            else:
+                for item in iterable:
+                    fp.write(item)
+        finally:
+            if close:
+                fp.close()
+
+    def disable_buffering(self):
+        """Disable the output buffering."""
+        self._next = partial(next, self._gen)
+        self.buffered = False
+
+    def _buffered_generator(self, size):
+        buf = []
+        c_size = 0
+        push = buf.append
+
+        while 1:
+            try:
+                while c_size < size:
+                    c = next(self._gen)
+                    push(c)
+                    if c:
+                        c_size += 1
+            except StopIteration:
+                if not c_size:
+                    return
+            yield concat(buf)
+            del buf[:]
+            c_size = 0
+
+    def enable_buffering(self, size=5):
+        """Enable buffering.  Buffer `size` items before yielding them."""
+        if size <= 1:
+            raise ValueError('buffer size too small')
+
+        self.buffered = True
+        self._next = partial(next, self._buffered_generator(size))
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self._next()
+
+
+# hook in default template class.  if anyone reads this comment: ignore that
+# it's possible to use custom templates ;-)
+Environment.template_class = Template
diff --git a/python/jinja2/exceptions.py b/python/jinja2/exceptions.py
new file mode 100644
index 0000000..c018a33
--- /dev/null
+++ b/python/jinja2/exceptions.py
@@ -0,0 +1,146 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.exceptions
+    ~~~~~~~~~~~~~~~~~
+
+    Jinja exceptions.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+from jinja2._compat import imap, text_type, PY2, implements_to_string
+
+
+class TemplateError(Exception):
+    """Baseclass for all template errors."""
+
+    if PY2:
+        def __init__(self, message=None):
+            if message is not None:
+                message = text_type(message).encode('utf-8')
+            Exception.__init__(self, message)
+
+        @property
+        def message(self):
+            if self.args:
+                message = self.args[0]
+                if message is not None:
+                    return message.decode('utf-8', 'replace')
+
+        def __unicode__(self):
+            return self.message or u''
+    else:
+        def __init__(self, message=None):
+            Exception.__init__(self, message)
+
+        @property
+        def message(self):
+            if self.args:
+                message = self.args[0]
+                if message is not None:
+                    return message
+
+
+@implements_to_string
+class TemplateNotFound(IOError, LookupError, TemplateError):
+    """Raised if a template does not exist."""
+
+    # looks weird, but removes the warning descriptor that just
+    # bogusly warns us about message being deprecated
+    message = None
+
+    def __init__(self, name, message=None):
+        IOError.__init__(self)
+        if message is None:
+            message = name
+        self.message = message
+        self.name = name
+        self.templates = [name]
+
+    def __str__(self):
+        return self.message
+
+
+class TemplatesNotFound(TemplateNotFound):
+    """Like :class:`TemplateNotFound` but raised if multiple templates
+    are selected.  This is a subclass of :class:`TemplateNotFound`
+    exception, so just catching the base exception will catch both.
+
+    .. versionadded:: 2.2
+    """
+
+    def __init__(self, names=(), message=None):
+        if message is None:
+            message = u'none of the templates given were found: ' + \
+                      u', '.join(imap(text_type, names))
+        TemplateNotFound.__init__(self, names and names[-1] or None, message)
+        self.templates = list(names)
+
+
+@implements_to_string
+class TemplateSyntaxError(TemplateError):
+    """Raised to tell the user that there is a problem with the template."""
+
+    def __init__(self, message, lineno, name=None, filename=None):
+        TemplateError.__init__(self, message)
+        self.lineno = lineno
+        self.name = name
+        self.filename = filename
+        self.source = None
+
+        # this is set to True if the debug.translate_syntax_error
+        # function translated the syntax error into a new traceback
+        self.translated = False
+
+    def __str__(self):
+        # for translated errors we only return the message
+        if self.translated:
+            return self.message
+
+        # otherwise attach some stuff
+        location = 'line %d' % self.lineno
+        name = self.filename or self.name
+        if name:
+            location = 'File "%s", %s' % (name, location)
+        lines = [self.message, '  ' + location]
+
+        # if the source is set, add the line to the output
+        if self.source is not None:
+            try:
+                line = self.source.splitlines()[self.lineno - 1]
+            except IndexError:
+                line = None
+            if line:
+                lines.append('    ' + line.strip())
+
+        return u'\n'.join(lines)
+
+
+class TemplateAssertionError(TemplateSyntaxError):
+    """Like a template syntax error, but covers cases where something in the
+    template caused an error at compile time that wasn't necessarily caused
+    by a syntax error.  However it's a direct subclass of
+    :exc:`TemplateSyntaxError` and has the same attributes.
+    """
+
+
+class TemplateRuntimeError(TemplateError):
+    """A generic runtime error in the template engine.  Under some situations
+    Jinja may raise this exception.
+    """
+
+
+class UndefinedError(TemplateRuntimeError):
+    """Raised if a template tries to operate on :class:`Undefined`."""
+
+
+class SecurityError(TemplateRuntimeError):
+    """Raised if a template tries to do something insecure if the
+    sandbox is enabled.
+    """
+
+
+class FilterArgumentError(TemplateRuntimeError):
+    """This error is raised if a filter was called with inappropriate
+    arguments
+    """
diff --git a/python/jinja2/ext.py b/python/jinja2/ext.py
new file mode 100644
index 0000000..0734a84
--- /dev/null
+++ b/python/jinja2/ext.py
@@ -0,0 +1,627 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.ext
+    ~~~~~~~~~~
+
+    Jinja extensions allow to add custom tags similar to the way django custom
+    tags work.  By default two example extensions exist: an i18n and a cache
+    extension.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+import re
+
+from jinja2 import nodes
+from jinja2.defaults import BLOCK_START_STRING, \
+     BLOCK_END_STRING, VARIABLE_START_STRING, VARIABLE_END_STRING, \
+     COMMENT_START_STRING, COMMENT_END_STRING, LINE_STATEMENT_PREFIX, \
+     LINE_COMMENT_PREFIX, TRIM_BLOCKS, NEWLINE_SEQUENCE, \
+     KEEP_TRAILING_NEWLINE, LSTRIP_BLOCKS
+from jinja2.environment import Environment
+from jinja2.runtime import concat
+from jinja2.exceptions import TemplateAssertionError, TemplateSyntaxError
+from jinja2.utils import contextfunction, import_string, Markup
+from jinja2._compat import with_metaclass, string_types, iteritems
+
+
+# the only real useful gettext functions for a Jinja template.  Note
+# that ugettext must be assigned to gettext as Jinja doesn't support
+# non unicode strings.
+GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext')
+
+
+class ExtensionRegistry(type):
+    """Gives the extension an unique identifier."""
+
+    def __new__(cls, name, bases, d):
+        rv = type.__new__(cls, name, bases, d)
+        rv.identifier = rv.__module__ + '.' + rv.__name__
+        return rv
+
+
+class Extension(with_metaclass(ExtensionRegistry, object)):
+    """Extensions can be used to add extra functionality to the Jinja template
+    system at the parser level.  Custom extensions are bound to an environment
+    but may not store environment specific data on `self`.  The reason for
+    this is that an extension can be bound to another environment (for
+    overlays) by creating a copy and reassigning the `environment` attribute.
+
+    As extensions are created by the environment they cannot accept any
+    arguments for configuration.  One may want to work around that by using
+    a factory function, but that is not possible as extensions are identified
+    by their import name.  The correct way to configure the extension is
+    storing the configuration values on the environment.  Because this way the
+    environment ends up acting as central configuration storage the
+    attributes may clash which is why extensions have to ensure that the names
+    they choose for configuration are not too generic.  ``prefix`` for example
+    is a terrible name, ``fragment_cache_prefix`` on the other hand is a good
+    name as includes the name of the extension (fragment cache).
+    """
+
+    #: if this extension parses this is the list of tags it's listening to.
+    tags = set()
+
+    #: the priority of that extension.  This is especially useful for
+    #: extensions that preprocess values.  A lower value means higher
+    #: priority.
+    #:
+    #: .. versionadded:: 2.4
+    priority = 100
+
+    def __init__(self, environment):
+        self.environment = environment
+
+    def bind(self, environment):
+        """Create a copy of this extension bound to another environment."""
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.environment = environment
+        return rv
+
+    def preprocess(self, source, name, filename=None):
+        """This method is called before the actual lexing and can be used to
+        preprocess the source.  The `filename` is optional.  The return value
+        must be the preprocessed source.
+        """
+        return source
+
+    def filter_stream(self, stream):
+        """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
+        to filter tokens returned.  This method has to return an iterable of
+        :class:`~jinja2.lexer.Token`\\s, but it doesn't have to return a
+        :class:`~jinja2.lexer.TokenStream`.
+
+        In the `ext` folder of the Jinja2 source distribution there is a file
+        called `inlinegettext.py` which implements a filter that utilizes this
+        method.
+        """
+        return stream
+
+    def parse(self, parser):
+        """If any of the :attr:`tags` matched this method is called with the
+        parser as first argument.  The token the parser stream is pointing at
+        is the name token that matched.  This method has to return one or a
+        list of multiple nodes.
+        """
+        raise NotImplementedError()
+
+    def attr(self, name, lineno=None):
+        """Return an attribute node for the current extension.  This is useful
+        to pass constants on extensions to generated template code.
+
+        ::
+
+            self.attr('_my_attribute', lineno=lineno)
+        """
+        return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
+
+    def call_method(self, name, args=None, kwargs=None, dyn_args=None,
+                    dyn_kwargs=None, lineno=None):
+        """Call a method of the extension.  This is a shortcut for
+        :meth:`attr` + :class:`jinja2.nodes.Call`.
+        """
+        if args is None:
+            args = []
+        if kwargs is None:
+            kwargs = []
+        return nodes.Call(self.attr(name, lineno=lineno), args, kwargs,
+                          dyn_args, dyn_kwargs, lineno=lineno)
+
+
+@contextfunction
+def _gettext_alias(__context, *args, **kwargs):
+    return __context.call(__context.resolve('gettext'), *args, **kwargs)
+
+
+def _make_new_gettext(func):
+    @contextfunction
+    def gettext(__context, __string, **variables):
+        rv = __context.call(func, __string)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        return rv % variables
+    return gettext
+
+
+def _make_new_ngettext(func):
+    @contextfunction
+    def ngettext(__context, __singular, __plural, __num, **variables):
+        variables.setdefault('num', __num)
+        rv = __context.call(func, __singular, __plural, __num)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        return rv % variables
+    return ngettext
+
+
+class InternationalizationExtension(Extension):
+    """This extension adds gettext support to Jinja2."""
+    tags = set(['trans'])
+
+    # TODO: the i18n extension is currently reevaluating values in a few
+    # situations.  Take this example:
+    #   {% trans count=something() %}{{ count }} foo{% pluralize
+    #     %}{{ count }} fooss{% endtrans %}
+    # something is called twice here.  One time for the gettext value and
+    # the other time for the n-parameter of the ngettext function.
+
+    def __init__(self, environment):
+        Extension.__init__(self, environment)
+        environment.globals['_'] = _gettext_alias
+        environment.extend(
+            install_gettext_translations=self._install,
+            install_null_translations=self._install_null,
+            install_gettext_callables=self._install_callables,
+            uninstall_gettext_translations=self._uninstall,
+            extract_translations=self._extract,
+            newstyle_gettext=False
+        )
+
+    def _install(self, translations, newstyle=None):
+        gettext = getattr(translations, 'ugettext', None)
+        if gettext is None:
+            gettext = translations.gettext
+        ngettext = getattr(translations, 'ungettext', None)
+        if ngettext is None:
+            ngettext = translations.ngettext
+        self._install_callables(gettext, ngettext, newstyle)
+
+    def _install_null(self, newstyle=None):
+        self._install_callables(
+            lambda x: x,
+            lambda s, p, n: (n != 1 and (p,) or (s,))[0],
+            newstyle
+        )
+
+    def _install_callables(self, gettext, ngettext, newstyle=None):
+        if newstyle is not None:
+            self.environment.newstyle_gettext = newstyle
+        if self.environment.newstyle_gettext:
+            gettext = _make_new_gettext(gettext)
+            ngettext = _make_new_ngettext(ngettext)
+        self.environment.globals.update(
+            gettext=gettext,
+            ngettext=ngettext
+        )
+
+    def _uninstall(self, translations):
+        for key in 'gettext', 'ngettext':
+            self.environment.globals.pop(key, None)
+
+    def _extract(self, source, gettext_functions=GETTEXT_FUNCTIONS):
+        if isinstance(source, string_types):
+            source = self.environment.parse(source)
+        return extract_from_ast(source, gettext_functions)
+
+    def parse(self, parser):
+        """Parse a translatable tag."""
+        lineno = next(parser.stream).lineno
+        num_called_num = False
+
+        # find all the variables referenced.  Additionally a variable can be
+        # defined in the body of the trans block too, but this is checked at
+        # a later state.
+        plural_expr = None
+        plural_expr_assignment = None
+        variables = {}
+        trimmed = None
+        while parser.stream.current.type != 'block_end':
+            if variables:
+                parser.stream.expect('comma')
+
+            # skip colon for python compatibility
+            if parser.stream.skip_if('colon'):
+                break
+
+            name = parser.stream.expect('name')
+            if name.value in variables:
+                parser.fail('translatable variable %r defined twice.' %
+                            name.value, name.lineno,
+                            exc=TemplateAssertionError)
+
+            # expressions
+            if parser.stream.current.type == 'assign':
+                next(parser.stream)
+                variables[name.value] = var = parser.parse_expression()
+            elif trimmed is None and name.value in ('trimmed', 'notrimmed'):
+                trimmed = name.value == 'trimmed'
+                continue
+            else:
+                variables[name.value] = var = nodes.Name(name.value, 'load')
+
+            if plural_expr is None:
+                if isinstance(var, nodes.Call):
+                    plural_expr = nodes.Name('_trans', 'load')
+                    variables[name.value] = plural_expr
+                    plural_expr_assignment = nodes.Assign(
+                        nodes.Name('_trans', 'store'), var)
+                else:
+                    plural_expr = var
+                num_called_num = name.value == 'num'
+
+        parser.stream.expect('block_end')
+
+        plural = None
+        have_plural = False
+        referenced = set()
+
+        # now parse until endtrans or pluralize
+        singular_names, singular = self._parse_block(parser, True)
+        if singular_names:
+            referenced.update(singular_names)
+            if plural_expr is None:
+                plural_expr = nodes.Name(singular_names[0], 'load')
+                num_called_num = singular_names[0] == 'num'
+
+        # if we have a pluralize block, we parse that too
+        if parser.stream.current.test('name:pluralize'):
+            have_plural = True
+            next(parser.stream)
+            if parser.stream.current.type != 'block_end':
+                name = parser.stream.expect('name')
+                if name.value not in variables:
+                    parser.fail('unknown variable %r for pluralization' %
+                                name.value, name.lineno,
+                                exc=TemplateAssertionError)
+                plural_expr = variables[name.value]
+                num_called_num = name.value == 'num'
+            parser.stream.expect('block_end')
+            plural_names, plural = self._parse_block(parser, False)
+            next(parser.stream)
+            referenced.update(plural_names)
+        else:
+            next(parser.stream)
+
+        # register free names as simple name expressions
+        for var in referenced:
+            if var not in variables:
+                variables[var] = nodes.Name(var, 'load')
+
+        if not have_plural:
+            plural_expr = None
+        elif plural_expr is None:
+            parser.fail('pluralize without variables', lineno)
+
+        if trimmed is None:
+            trimmed = self.environment.policies['ext.i18n.trimmed']
+        if trimmed:
+            singular = self._trim_whitespace(singular)
+            if plural:
+                plural = self._trim_whitespace(plural)
+
+        node = self._make_node(singular, plural, variables, plural_expr,
+                               bool(referenced),
+                               num_called_num and have_plural)
+        node.set_lineno(lineno)
+        if plural_expr_assignment is not None:
+            return [plural_expr_assignment, node]
+        else:
+            return node
+
+    def _trim_whitespace(self, string, _ws_re=re.compile(r'\s*\n\s*')):
+        return _ws_re.sub(' ', string.strip())
+
+    def _parse_block(self, parser, allow_pluralize):
+        """Parse until the next block tag with a given name."""
+        referenced = []
+        buf = []
+        while 1:
+            if parser.stream.current.type == 'data':
+                buf.append(parser.stream.current.value.replace('%', '%%'))
+                next(parser.stream)
+            elif parser.stream.current.type == 'variable_begin':
+                next(parser.stream)
+                name = parser.stream.expect('name').value
+                referenced.append(name)
+                buf.append('%%(%s)s' % name)
+                parser.stream.expect('variable_end')
+            elif parser.stream.current.type == 'block_begin':
+                next(parser.stream)
+                if parser.stream.current.test('name:endtrans'):
+                    break
+                elif parser.stream.current.test('name:pluralize'):
+                    if allow_pluralize:
+                        break
+                    parser.fail('a translatable section can have only one '
+                                'pluralize section')
+                parser.fail('control structures in translatable sections are '
+                            'not allowed')
+            elif parser.stream.eos:
+                parser.fail('unclosed translation block')
+            else:
+                assert False, 'internal parser error'
+
+        return referenced, concat(buf)
+
+    def _make_node(self, singular, plural, variables, plural_expr,
+                   vars_referenced, num_called_num):
+        """Generates a useful node from the data provided."""
+        # no variables referenced?  no need to escape for old style
+        # gettext invocations only if there are vars.
+        if not vars_referenced and not self.environment.newstyle_gettext:
+            singular = singular.replace('%%', '%')
+            if plural:
+                plural = plural.replace('%%', '%')
+
+        # singular only:
+        if plural_expr is None:
+            gettext = nodes.Name('gettext', 'load')
+            node = nodes.Call(gettext, [nodes.Const(singular)],
+                              [], None, None)
+
+        # singular and plural
+        else:
+            ngettext = nodes.Name('ngettext', 'load')
+            node = nodes.Call(ngettext, [
+                nodes.Const(singular),
+                nodes.Const(plural),
+                plural_expr
+            ], [], None, None)
+
+        # in case newstyle gettext is used, the method is powerful
+        # enough to handle the variable expansion and autoescape
+        # handling itself
+        if self.environment.newstyle_gettext:
+            for key, value in iteritems(variables):
+                # the function adds that later anyways in case num was
+                # called num, so just skip it.
+                if num_called_num and key == 'num':
+                    continue
+                node.kwargs.append(nodes.Keyword(key, value))
+
+        # otherwise do that here
+        else:
+            # mark the return value as safe if we are in an
+            # environment with autoescaping turned on
+            node = nodes.MarkSafeIfAutoescape(node)
+            if variables:
+                node = nodes.Mod(node, nodes.Dict([
+                    nodes.Pair(nodes.Const(key), value)
+                    for key, value in variables.items()
+                ]))
+        return nodes.Output([node])
+
+
+class ExprStmtExtension(Extension):
+    """Adds a `do` tag to Jinja2 that works like the print statement just
+    that it doesn't print the return value.
+    """
+    tags = set(['do'])
+
+    def parse(self, parser):
+        node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
+        node.node = parser.parse_tuple()
+        return node
+
+
+class LoopControlExtension(Extension):
+    """Adds break and continue to the template engine."""
+    tags = set(['break', 'continue'])
+
+    def parse(self, parser):
+        token = next(parser.stream)
+        if token.value == 'break':
+            return nodes.Break(lineno=token.lineno)
+        return nodes.Continue(lineno=token.lineno)
+
+
+class WithExtension(Extension):
+    pass
+
+
+class AutoEscapeExtension(Extension):
+    pass
+
+
+def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS,
+                     babel_style=True):
+    """Extract localizable strings from the given template node.  Per
+    default this function returns matches in babel style that means non string
+    parameters as well as keyword arguments are returned as `None`.  This
+    allows Babel to figure out what you really meant if you are using
+    gettext functions that allow keyword arguments for placeholder expansion.
+    If you don't want that behavior set the `babel_style` parameter to `False`
+    which causes only strings to be returned and parameters are always stored
+    in tuples.  As a consequence invalid gettext calls (calls without a single
+    string parameter or string parameters after non-string parameters) are
+    skipped.
+
+    This example explains the behavior:
+
+    >>> from jinja2 import Environment
+    >>> env = Environment()
+    >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
+    >>> list(extract_from_ast(node))
+    [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
+    >>> list(extract_from_ast(node, babel_style=False))
+    [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
+
+    For every string found this function yields a ``(lineno, function,
+    message)`` tuple, where:
+
+    * ``lineno`` is the number of the line on which the string was found,
+    * ``function`` is the name of the ``gettext`` function used (if the
+      string was extracted from embedded Python code), and
+    *  ``message`` is the string itself (a ``unicode`` object, or a tuple
+       of ``unicode`` objects for functions with multiple string arguments).
+
+    This extraction function operates on the AST and is because of that unable
+    to extract any comments.  For comment support you have to use the babel
+    extraction interface or extract comments yourself.
+    """
+    for node in node.find_all(nodes.Call):
+        if not isinstance(node.node, nodes.Name) or \
+           node.node.name not in gettext_functions:
+            continue
+
+        strings = []
+        for arg in node.args:
+            if isinstance(arg, nodes.Const) and \
+               isinstance(arg.value, string_types):
+                strings.append(arg.value)
+            else:
+                strings.append(None)
+
+        for arg in node.kwargs:
+            strings.append(None)
+        if node.dyn_args is not None:
+            strings.append(None)
+        if node.dyn_kwargs is not None:
+            strings.append(None)
+
+        if not babel_style:
+            strings = tuple(x for x in strings if x is not None)
+            if not strings:
+                continue
+        else:
+            if len(strings) == 1:
+                strings = strings[0]
+            else:
+                strings = tuple(strings)
+        yield node.lineno, node.node.name, strings
+
+
+class _CommentFinder(object):
+    """Helper class to find comments in a token stream.  Can only
+    find comments for gettext calls forwards.  Once the comment
+    from line 4 is found, a comment for line 1 will not return a
+    usable value.
+    """
+
+    def __init__(self, tokens, comment_tags):
+        self.tokens = tokens
+        self.comment_tags = comment_tags
+        self.offset = 0
+        self.last_lineno = 0
+
+    def find_backwards(self, offset):
+        try:
+            for _, token_type, token_value in \
+                    reversed(self.tokens[self.offset:offset]):
+                if token_type in ('comment', 'linecomment'):
+                    try:
+                        prefix, comment = token_value.split(None, 1)
+                    except ValueError:
+                        continue
+                    if prefix in self.comment_tags:
+                        return [comment.rstrip()]
+            return []
+        finally:
+            self.offset = offset
+
+    def find_comments(self, lineno):
+        if not self.comment_tags or self.last_lineno > lineno:
+            return []
+        for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset:]):
+            if token_lineno > lineno:
+                return self.find_backwards(self.offset + idx)
+        return self.find_backwards(len(self.tokens))
+
+
+def babel_extract(fileobj, keywords, comment_tags, options):
+    """Babel extraction method for Jinja templates.
+
+    .. versionchanged:: 2.3
+       Basic support for translation comments was added.  If `comment_tags`
+       is now set to a list of keywords for extraction, the extractor will
+       try to find the best preceeding comment that begins with one of the
+       keywords.  For best results, make sure to not have more than one
+       gettext call in one line of code and the matching comment in the
+       same line or the line before.
+
+    .. versionchanged:: 2.5.1
+       The `newstyle_gettext` flag can be set to `True` to enable newstyle
+       gettext calls.
+
+    .. versionchanged:: 2.7
+       A `silent` option can now be provided.  If set to `False` template
+       syntax errors are propagated instead of being ignored.
+
+    :param fileobj: the file-like object the messages should be extracted from
+    :param keywords: a list of keywords (i.e. function names) that should be
+                     recognized as translation functions
+    :param comment_tags: a list of translator tags to search for and include
+                         in the results.
+    :param options: a dictionary of additional options (optional)
+    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
+             (comments will be empty currently)
+    """
+    extensions = set()
+    for extension in options.get('extensions', '').split(','):
+        extension = extension.strip()
+        if not extension:
+            continue
+        extensions.add(import_string(extension))
+    if InternationalizationExtension not in extensions:
+        extensions.add(InternationalizationExtension)
+
+    def getbool(options, key, default=False):
+        return options.get(key, str(default)).lower() in \
+            ('1', 'on', 'yes', 'true')
+
+    silent = getbool(options, 'silent', True)
+    environment = Environment(
+        options.get('block_start_string', BLOCK_START_STRING),
+        options.get('block_end_string', BLOCK_END_STRING),
+        options.get('variable_start_string', VARIABLE_START_STRING),
+        options.get('variable_end_string', VARIABLE_END_STRING),
+        options.get('comment_start_string', COMMENT_START_STRING),
+        options.get('comment_end_string', COMMENT_END_STRING),
+        options.get('line_statement_prefix') or LINE_STATEMENT_PREFIX,
+        options.get('line_comment_prefix') or LINE_COMMENT_PREFIX,
+        getbool(options, 'trim_blocks', TRIM_BLOCKS),
+        getbool(options, 'lstrip_blocks', LSTRIP_BLOCKS),
+        NEWLINE_SEQUENCE,
+        getbool(options, 'keep_trailing_newline', KEEP_TRAILING_NEWLINE),
+        frozenset(extensions),
+        cache_size=0,
+        auto_reload=False
+    )
+
+    if getbool(options, 'trimmed'):
+        environment.policies['ext.i18n.trimmed'] = True
+    if getbool(options, 'newstyle_gettext'):
+        environment.newstyle_gettext = True
+
+    source = fileobj.read().decode(options.get('encoding', 'utf-8'))
+    try:
+        node = environment.parse(source)
+        tokens = list(environment.lex(environment.preprocess(source)))
+    except TemplateSyntaxError as e:
+        if not silent:
+            raise
+        # skip templates with syntax errors
+        return
+
+    finder = _CommentFinder(tokens, comment_tags)
+    for lineno, func, message in extract_from_ast(node, keywords):
+        yield lineno, func, message, finder.find_comments(lineno)
+
+
+#: nicer import names
+i18n = InternationalizationExtension
+do = ExprStmtExtension
+loopcontrols = LoopControlExtension
+with_ = WithExtension
+autoescape = AutoEscapeExtension
diff --git a/python/jinja2/filters.py b/python/jinja2/filters.py
new file mode 100644
index 0000000..267dddd
--- /dev/null
+++ b/python/jinja2/filters.py
@@ -0,0 +1,1190 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.filters
+    ~~~~~~~~~~~~~~
+
+    Bundled jinja filters.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import re
+import math
+import random
+import warnings
+
+from itertools import groupby, chain
+from collections import namedtuple
+from jinja2.utils import Markup, escape, pformat, urlize, soft_unicode, \
+     unicode_urlencode, htmlsafe_json_dumps
+from jinja2.runtime import Undefined
+from jinja2.exceptions import FilterArgumentError
+from jinja2._compat import imap, string_types, text_type, iteritems, PY2
+
+
+_word_re = re.compile(r'\w+', re.UNICODE)
+_word_beginning_split_re = re.compile(r'([-\s\(\{\[\<]+)', re.UNICODE)
+
+
+def contextfilter(f):
+    """Decorator for marking context dependent filters. The current
+    :class:`Context` will be passed as first argument.
+    """
+    f.contextfilter = True
+    return f
+
+
+def evalcontextfilter(f):
+    """Decorator for marking eval-context dependent filters.  An eval
+    context object is passed as first argument.  For more information
+    about the eval context, see :ref:`eval-context`.
+
+    .. versionadded:: 2.4
+    """
+    f.evalcontextfilter = True
+    return f
+
+
+def environmentfilter(f):
+    """Decorator for marking environment dependent filters.  The current
+    :class:`Environment` is passed to the filter as first argument.
+    """
+    f.environmentfilter = True
+    return f
+
+
+def ignore_case(value):
+    """For use as a postprocessor for :func:`make_attrgetter`. Converts strings
+    to lowercase and returns other types as-is."""
+    return value.lower() if isinstance(value, string_types) else value
+
+
+def make_attrgetter(environment, attribute, postprocess=None):
+    """Returns a callable that looks up the given attribute from a
+    passed object with the rules of the environment.  Dots are allowed
+    to access attributes of attributes.  Integer parts in paths are
+    looked up as integers.
+    """
+    if attribute is None:
+        attribute = []
+    elif isinstance(attribute, string_types):
+        attribute = [int(x) if x.isdigit() else x for x in attribute.split('.')]
+    else:
+        attribute = [attribute]
+
+    def attrgetter(item):
+        for part in attribute:
+            item = environment.getitem(item, part)
+
+        if postprocess is not None:
+            item = postprocess(item)
+
+        return item
+
+    return attrgetter
+
+
+def do_forceescape(value):
+    """Enforce HTML escaping.  This will probably double escape variables."""
+    if hasattr(value, '__html__'):
+        value = value.__html__()
+    return escape(text_type(value))
+
+
+def do_urlencode(value):
+    """Escape strings for use in URLs (uses UTF-8 encoding).  It accepts both
+    dictionaries and regular strings as well as pairwise iterables.
+
+    .. versionadded:: 2.7
+    """
+    itemiter = None
+    if isinstance(value, dict):
+        itemiter = iteritems(value)
+    elif not isinstance(value, string_types):
+        try:
+            itemiter = iter(value)
+        except TypeError:
+            pass
+    if itemiter is None:
+        return unicode_urlencode(value)
+    return u'&'.join(unicode_urlencode(k) + '=' +
+                     unicode_urlencode(v, for_qs=True)
+                     for k, v in itemiter)
+
+
+@evalcontextfilter
+def do_replace(eval_ctx, s, old, new, count=None):
+    """Return a copy of the value with all occurrences of a substring
+    replaced with a new one. The first argument is the substring
+    that should be replaced, the second is the replacement string.
+    If the optional third argument ``count`` is given, only the first
+    ``count`` occurrences are replaced:
+
+    .. sourcecode:: jinja
+
+        {{ "Hello World"|replace("Hello", "Goodbye") }}
+            -> Goodbye World
+
+        {{ "aaaaargh"|replace("a", "d'oh, ", 2) }}
+            -> d'oh, d'oh, aaargh
+    """
+    if count is None:
+        count = -1
+    if not eval_ctx.autoescape:
+        return text_type(s).replace(text_type(old), text_type(new), count)
+    if hasattr(old, '__html__') or hasattr(new, '__html__') and \
+       not hasattr(s, '__html__'):
+        s = escape(s)
+    else:
+        s = soft_unicode(s)
+    return s.replace(soft_unicode(old), soft_unicode(new), count)
+
+
+def do_upper(s):
+    """Convert a value to uppercase."""
+    return soft_unicode(s).upper()
+
+
+def do_lower(s):
+    """Convert a value to lowercase."""
+    return soft_unicode(s).lower()
+
+
+@evalcontextfilter
+def do_xmlattr(_eval_ctx, d, autospace=True):
+    """Create an SGML/XML attribute string based on the items in a dict.
+    All values that are neither `none` nor `undefined` are automatically
+    escaped:
+
+    .. sourcecode:: html+jinja
+
+        <ul{{ {'class': 'my_list', 'missing': none,
+                'id': 'list-%d'|format(variable)}|xmlattr }}>
+        ...
+        </ul>
+
+    Results in something like this:
+
+    .. sourcecode:: html
+
+        <ul class="my_list" id="list-42">
+        ...
+        </ul>
+
+    As you can see it automatically prepends a space in front of the item
+    if the filter returned something unless the second parameter is false.
+    """
+    rv = u' '.join(
+        u'%s="%s"' % (escape(key), escape(value))
+        for key, value in iteritems(d)
+        if value is not None and not isinstance(value, Undefined)
+    )
+    if autospace and rv:
+        rv = u' ' + rv
+    if _eval_ctx.autoescape:
+        rv = Markup(rv)
+    return rv
+
+
+def do_capitalize(s):
+    """Capitalize a value. The first character will be uppercase, all others
+    lowercase.
+    """
+    return soft_unicode(s).capitalize()
+
+
+def do_title(s):
+    """Return a titlecased version of the value. I.e. words will start with
+    uppercase letters, all remaining characters are lowercase.
+    """
+    return ''.join(
+        [item[0].upper() + item[1:].lower()
+         for item in _word_beginning_split_re.split(soft_unicode(s))
+         if item])
+
+
+def do_dictsort(value, case_sensitive=False, by='key', reverse=False):
+    """Sort a dict and yield (key, value) pairs. Because python dicts are
+    unsorted you may want to use this function to order them by either
+    key or value:
+
+    .. sourcecode:: jinja
+
+        {% for item in mydict|dictsort %}
+            sort the dict by key, case insensitive
+
+        {% for item in mydict|dictsort(reverse=true) %}
+            sort the dict by key, case insensitive, reverse order
+
+        {% for item in mydict|dictsort(true) %}
+            sort the dict by key, case sensitive
+
+        {% for item in mydict|dictsort(false, 'value') %}
+            sort the dict by value, case insensitive
+    """
+    if by == 'key':
+        pos = 0
+    elif by == 'value':
+        pos = 1
+    else:
+        raise FilterArgumentError(
+            'You can only sort by either "key" or "value"'
+        )
+
+    def sort_func(item):
+        value = item[pos]
+
+        if not case_sensitive:
+            value = ignore_case(value)
+
+        return value
+
+    return sorted(value.items(), key=sort_func, reverse=reverse)
+
+
+@environmentfilter
+def do_sort(
+    environment, value, reverse=False, case_sensitive=False, attribute=None
+):
+    """Sort an iterable.  Per default it sorts ascending, if you pass it
+    true as first argument it will reverse the sorting.
+
+    If the iterable is made of strings the third parameter can be used to
+    control the case sensitiveness of the comparison which is disabled by
+    default.
+
+    .. sourcecode:: jinja
+
+        {% for item in iterable|sort %}
+            ...
+        {% endfor %}
+
+    It is also possible to sort by an attribute (for example to sort
+    by the date of an object) by specifying the `attribute` parameter:
+
+    .. sourcecode:: jinja
+
+        {% for item in iterable|sort(attribute='date') %}
+            ...
+        {% endfor %}
+
+    .. versionchanged:: 2.6
+       The `attribute` parameter was added.
+    """
+    key_func = make_attrgetter(
+        environment, attribute,
+        postprocess=ignore_case if not case_sensitive else None
+    )
+    return sorted(value, key=key_func, reverse=reverse)
+
+
+@environmentfilter
+def do_unique(environment, value, case_sensitive=False, attribute=None):
+    """Returns a list of unique items from the the given iterable.
+
+    .. sourcecode:: jinja
+
+        {{ ['foo', 'bar', 'foobar', 'FooBar']|unique }}
+            -> ['foo', 'bar', 'foobar']
+
+    The unique items are yielded in the same order as their first occurrence in
+    the iterable passed to the filter.
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Filter objects with unique values for this attribute.
+    """
+    getter = make_attrgetter(
+        environment, attribute,
+        postprocess=ignore_case if not case_sensitive else None
+    )
+    seen = set()
+
+    for item in value:
+        key = getter(item)
+
+        if key not in seen:
+            seen.add(key)
+            yield item
+
+
+def _min_or_max(environment, value, func, case_sensitive, attribute):
+    it = iter(value)
+
+    try:
+        first = next(it)
+    except StopIteration:
+        return environment.undefined('No aggregated item, sequence was empty.')
+
+    key_func = make_attrgetter(
+        environment, attribute,
+        ignore_case if not case_sensitive else None
+    )
+    return func(chain([first], it), key=key_func)
+
+
+@environmentfilter
+def do_min(environment, value, case_sensitive=False, attribute=None):
+    """Return the smallest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|min }}
+            -> 1
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the max value of this attribute.
+    """
+    return _min_or_max(environment, value, min, case_sensitive, attribute)
+
+
+@environmentfilter
+def do_max(environment, value, case_sensitive=False, attribute=None):
+    """Return the largest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|max }}
+            -> 3
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the max value of this attribute.
+    """
+    return _min_or_max(environment, value, max, case_sensitive, attribute)
+
+
+def do_default(value, default_value=u'', boolean=False):
+    """If the value is undefined it will return the passed default value,
+    otherwise the value of the variable:
+
+    .. sourcecode:: jinja
+
+        {{ my_variable|default('my_variable is not defined') }}
+
+    This will output the value of ``my_variable`` if the variable was
+    defined, otherwise ``'my_variable is not defined'``. If you want
+    to use default with variables that evaluate to false you have to
+    set the second parameter to `true`:
+
+    .. sourcecode:: jinja
+
+        {{ ''|default('the string was empty', true) }}
+    """
+    if isinstance(value, Undefined) or (boolean and not value):
+        return default_value
+    return value
+
+
+@evalcontextfilter
+def do_join(eval_ctx, value, d=u'', attribute=None):
+    """Return a string which is the concatenation of the strings in the
+    sequence. The separator between elements is an empty string per
+    default, you can define it with the optional parameter:
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|join('|') }}
+            -> 1|2|3
+
+        {{ [1, 2, 3]|join }}
+            -> 123
+
+    It is also possible to join certain attributes of an object:
+
+    .. sourcecode:: jinja
+
+        {{ users|join(', ', attribute='username') }}
+
+    .. versionadded:: 2.6
+       The `attribute` parameter was added.
+    """
+    if attribute is not None:
+        value = imap(make_attrgetter(eval_ctx.environment, attribute), value)
+
+    # no automatic escaping?  joining is a lot eaiser then
+    if not eval_ctx.autoescape:
+        return text_type(d).join(imap(text_type, value))
+
+    # if the delimiter doesn't have an html representation we check
+    # if any of the items has.  If yes we do a coercion to Markup
+    if not hasattr(d, '__html__'):
+        value = list(value)
+        do_escape = False
+        for idx, item in enumerate(value):
+            if hasattr(item, '__html__'):
+                do_escape = True
+            else:
+                value[idx] = text_type(item)
+        if do_escape:
+            d = escape(d)
+        else:
+            d = text_type(d)
+        return d.join(value)
+
+    # no html involved, to normal joining
+    return soft_unicode(d).join(imap(soft_unicode, value))
+
+
+def do_center(value, width=80):
+    """Centers the value in a field of a given width."""
+    return text_type(value).center(width)
+
+
+@environmentfilter
+def do_first(environment, seq):
+    """Return the first item of a sequence."""
+    try:
+        return next(iter(seq))
+    except StopIteration:
+        return environment.undefined('No first item, sequence was empty.')
+
+
+@environmentfilter
+def do_last(environment, seq):
+    """Return the last item of a sequence."""
+    try:
+        return next(iter(reversed(seq)))
+    except StopIteration:
+        return environment.undefined('No last item, sequence was empty.')
+
+
+@contextfilter
+def do_random(context, seq):
+    """Return a random item from the sequence."""
+    try:
+        return random.choice(seq)
+    except IndexError:
+        return context.environment.undefined('No random item, sequence was empty.')
+
+
+def do_filesizeformat(value, binary=False):
+    """Format the value like a 'human-readable' file size (i.e. 13 kB,
+    4.1 MB, 102 Bytes, etc).  Per default decimal prefixes are used (Mega,
+    Giga, etc.), if the second parameter is set to `True` the binary
+    prefixes are used (Mebi, Gibi).
+    """
+    bytes = float(value)
+    base = binary and 1024 or 1000
+    prefixes = [
+        (binary and 'KiB' or 'kB'),
+        (binary and 'MiB' or 'MB'),
+        (binary and 'GiB' or 'GB'),
+        (binary and 'TiB' or 'TB'),
+        (binary and 'PiB' or 'PB'),
+        (binary and 'EiB' or 'EB'),
+        (binary and 'ZiB' or 'ZB'),
+        (binary and 'YiB' or 'YB')
+    ]
+    if bytes == 1:
+        return '1 Byte'
+    elif bytes < base:
+        return '%d Bytes' % bytes
+    else:
+        for i, prefix in enumerate(prefixes):
+            unit = base ** (i + 2)
+            if bytes < unit:
+                return '%.1f %s' % ((base * bytes / unit), prefix)
+        return '%.1f %s' % ((base * bytes / unit), prefix)
+
+
+def do_pprint(value, verbose=False):
+    """Pretty print a variable. Useful for debugging.
+
+    With Jinja 1.2 onwards you can pass it a parameter.  If this parameter
+    is truthy the output will be more verbose (this requires `pretty`)
+    """
+    return pformat(value, verbose=verbose)
+
+
+@evalcontextfilter
+def do_urlize(eval_ctx, value, trim_url_limit=None, nofollow=False,
+              target=None, rel=None):
+    """Converts URLs in plain text into clickable links.
+
+    If you pass the filter an additional integer it will shorten the urls
+    to that number. Also a third argument exists that makes the urls
+    "nofollow":
+
+    .. sourcecode:: jinja
+
+        {{ mytext|urlize(40, true) }}
+            links are shortened to 40 chars and defined with rel="nofollow"
+
+    If *target* is specified, the ``target`` attribute will be added to the
+    ``<a>`` tag:
+
+    .. sourcecode:: jinja
+
+       {{ mytext|urlize(40, target='_blank') }}
+
+    .. versionchanged:: 2.8+
+       The *target* parameter was added.
+    """
+    policies = eval_ctx.environment.policies
+    rel = set((rel or '').split() or [])
+    if nofollow:
+        rel.add('nofollow')
+    rel.update((policies['urlize.rel'] or '').split())
+    if target is None:
+        target = policies['urlize.target']
+    rel = ' '.join(sorted(rel)) or None
+    rv = urlize(value, trim_url_limit, rel=rel, target=target)
+    if eval_ctx.autoescape:
+        rv = Markup(rv)
+    return rv
+
+
+def do_indent(
+    s, width=4, first=False, blank=False, indentfirst=None
+):
+    """Return a copy of the string with each line indented by 4 spaces. The
+    first line and blank lines are not indented by default.
+
+    :param width: Number of spaces to indent by.
+    :param first: Don't skip indenting the first line.
+    :param blank: Don't skip indenting empty lines.
+
+    .. versionchanged:: 2.10
+        Blank lines are not indented by default.
+
+        Rename the ``indentfirst`` argument to ``first``.
+    """
+    if indentfirst is not None:
+        warnings.warn(DeprecationWarning(
+            'The "indentfirst" argument is renamed to "first".'
+        ), stacklevel=2)
+        first = indentfirst
+
+    s += u'\n'  # this quirk is necessary for splitlines method
+    indention = u' ' * width
+
+    if blank:
+        rv = (u'\n' + indention).join(s.splitlines())
+    else:
+        lines = s.splitlines()
+        rv = lines.pop(0)
+
+        if lines:
+            rv += u'\n' + u'\n'.join(
+                indention + line if line else line for line in lines
+            )
+
+    if first:
+        rv = indention + rv
+
+    return rv
+
+
+@environmentfilter
+def do_truncate(env, s, length=255, killwords=False, end='...', leeway=None):
+    """Return a truncated copy of the string. The length is specified
+    with the first parameter which defaults to ``255``. If the second
+    parameter is ``true`` the filter will cut the text at length. Otherwise
+    it will discard the last word. If the text was in fact
+    truncated it will append an ellipsis sign (``"..."``). If you want a
+    different ellipsis sign than ``"..."`` you can specify it using the
+    third parameter. Strings that only exceed the length by the tolerance
+    margin given in the fourth parameter will not be truncated.
+
+    .. sourcecode:: jinja
+
+        {{ "foo bar baz qux"|truncate(9) }}
+            -> "foo..."
+        {{ "foo bar baz qux"|truncate(9, True) }}
+            -> "foo ba..."
+        {{ "foo bar baz qux"|truncate(11) }}
+            -> "foo bar baz qux"
+        {{ "foo bar baz qux"|truncate(11, False, '...', 0) }}
+            -> "foo bar..."
+
+    The default leeway on newer Jinja2 versions is 5 and was 0 before but
+    can be reconfigured globally.
+    """
+    if leeway is None:
+        leeway = env.policies['truncate.leeway']
+    assert length >= len(end), 'expected length >= %s, got %s' % (len(end), length)
+    assert leeway >= 0, 'expected leeway >= 0, got %s' % leeway
+    if len(s) <= length + leeway:
+        return s
+    if killwords:
+        return s[:length - len(end)] + end
+    result = s[:length - len(end)].rsplit(' ', 1)[0]
+    return result + end
+
+
+@environmentfilter
+def do_wordwrap(environment, s, width=79, break_long_words=True,
+                wrapstring=None):
+    """
+    Return a copy of the string passed to the filter wrapped after
+    ``79`` characters.  You can override this default using the first
+    parameter.  If you set the second parameter to `false` Jinja will not
+    split words apart if they are longer than `width`. By default, the newlines
+    will be the default newlines for the environment, but this can be changed
+    using the wrapstring keyword argument.
+
+    .. versionadded:: 2.7
+       Added support for the `wrapstring` parameter.
+    """
+    if not wrapstring:
+        wrapstring = environment.newline_sequence
+    import textwrap
+    return wrapstring.join(textwrap.wrap(s, width=width, expand_tabs=False,
+                                   replace_whitespace=False,
+                                   break_long_words=break_long_words))
+
+
+def do_wordcount(s):
+    """Count the words in that string."""
+    return len(_word_re.findall(s))
+
+
+def do_int(value, default=0, base=10):
+    """Convert the value into an integer. If the
+    conversion doesn't work it will return ``0``. You can
+    override this default using the first parameter. You
+    can also override the default base (10) in the second
+    parameter, which handles input with prefixes such as
+    0b, 0o and 0x for bases 2, 8 and 16 respectively.
+    The base is ignored for decimal numbers and non-string values.
+    """
+    try:
+        if isinstance(value, string_types):
+            return int(value, base)
+        return int(value)
+    except (TypeError, ValueError):
+        # this quirk is necessary so that "42.23"|int gives 42.
+        try:
+            return int(float(value))
+        except (TypeError, ValueError):
+            return default
+
+
+def do_float(value, default=0.0):
+    """Convert the value into a floating point number. If the
+    conversion doesn't work it will return ``0.0``. You can
+    override this default using the first parameter.
+    """
+    try:
+        return float(value)
+    except (TypeError, ValueError):
+        return default
+
+
+def do_format(value, *args, **kwargs):
+    """
+    Apply python string formatting on an object:
+
+    .. sourcecode:: jinja
+
+        {{ "%s - %s"|format("Hello?", "Foo!") }}
+            -> Hello? - Foo!
+    """
+    if args and kwargs:
+        raise FilterArgumentError('can\'t handle positional and keyword '
+                                  'arguments at the same time')
+    return soft_unicode(value) % (kwargs or args)
+
+
+def do_trim(value):
+    """Strip leading and trailing whitespace."""
+    return soft_unicode(value).strip()
+
+
+def do_striptags(value):
+    """Strip SGML/XML tags and replace adjacent whitespace by one space.
+    """
+    if hasattr(value, '__html__'):
+        value = value.__html__()
+    return Markup(text_type(value)).striptags()
+
+
+def do_slice(value, slices, fill_with=None):
+    """Slice an iterator and return a list of lists containing
+    those items. Useful if you want to create a div containing
+    three ul tags that represent columns:
+
+    .. sourcecode:: html+jinja
+
+        <div class="columwrapper">
+          {%- for column in items|slice(3) %}
+            <ul class="column-{{ loop.index }}">
+            {%- for item in column %}
+              <li>{{ item }}</li>
+            {%- endfor %}
+            </ul>
+          {%- endfor %}
+        </div>
+
+    If you pass it a second argument it's used to fill missing
+    values on the last iteration.
+    """
+    seq = list(value)
+    length = len(seq)
+    items_per_slice = length // slices
+    slices_with_extra = length % slices
+    offset = 0
+    for slice_number in range(slices):
+        start = offset + slice_number * items_per_slice
+        if slice_number < slices_with_extra:
+            offset += 1
+        end = offset + (slice_number + 1) * items_per_slice
+        tmp = seq[start:end]
+        if fill_with is not None and slice_number >= slices_with_extra:
+            tmp.append(fill_with)
+        yield tmp
+
+
+def do_batch(value, linecount, fill_with=None):
+    """
+    A filter that batches items. It works pretty much like `slice`
+    just the other way round. It returns a list of lists with the
+    given number of items. If you provide a second parameter this
+    is used to fill up missing items. See this example:
+
+    .. sourcecode:: html+jinja
+
+        <table>
+        {%- for row in items|batch(3, '&nbsp;') %}
+          <tr>
+          {%- for column in row %}
+            <td>{{ column }}</td>
+          {%- endfor %}
+          </tr>
+        {%- endfor %}
+        </table>
+    """
+    tmp = []
+    for item in value:
+        if len(tmp) == linecount:
+            yield tmp
+            tmp = []
+        tmp.append(item)
+    if tmp:
+        if fill_with is not None and len(tmp) < linecount:
+            tmp += [fill_with] * (linecount - len(tmp))
+        yield tmp
+
+
+def do_round(value, precision=0, method='common'):
+    """Round the number to a given precision. The first
+    parameter specifies the precision (default is ``0``), the
+    second the rounding method:
+
+    - ``'common'`` rounds either up or down
+    - ``'ceil'`` always rounds up
+    - ``'floor'`` always rounds down
+
+    If you don't specify a method ``'common'`` is used.
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round }}
+            -> 43.0
+        {{ 42.55|round(1, 'floor') }}
+            -> 42.5
+
+    Note that even if rounded to 0 precision, a float is returned.  If
+    you need a real integer, pipe it through `int`:
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round|int }}
+            -> 43
+    """
+    if not method in ('common', 'ceil', 'floor'):
+        raise FilterArgumentError('method must be common, ceil or floor')
+    if method == 'common':
+        return round(value, precision)
+    func = getattr(math, method)
+    return func(value * (10 ** precision)) / (10 ** precision)
+
+
+# Use a regular tuple repr here.  This is what we did in the past and we
+# really want to hide this custom type as much as possible.  In particular
+# we do not want to accidentally expose an auto generated repr in case
+# people start to print this out in comments or something similar for
+# debugging.
+_GroupTuple = namedtuple('_GroupTuple', ['grouper', 'list'])
+_GroupTuple.__repr__ = tuple.__repr__
+_GroupTuple.__str__ = tuple.__str__
+
+@environmentfilter
+def do_groupby(environment, value, attribute):
+    """Group a sequence of objects by a common attribute.
+
+    If you for example have a list of dicts or objects that represent persons
+    with `gender`, `first_name` and `last_name` attributes and you want to
+    group all users by genders you can do something like the following
+    snippet:
+
+    .. sourcecode:: html+jinja
+
+        <ul>
+        {% for group in persons|groupby('gender') %}
+            <li>{{ group.grouper }}<ul>
+            {% for person in group.list %}
+                <li>{{ person.first_name }} {{ person.last_name }}</li>
+            {% endfor %}</ul></li>
+        {% endfor %}
+        </ul>
+
+    Additionally it's possible to use tuple unpacking for the grouper and
+    list:
+
+    .. sourcecode:: html+jinja
+
+        <ul>
+        {% for grouper, list in persons|groupby('gender') %}
+            ...
+        {% endfor %}
+        </ul>
+
+    As you can see the item we're grouping by is stored in the `grouper`
+    attribute and the `list` contains all the objects that have this grouper
+    in common.
+
+    .. versionchanged:: 2.6
+       It's now possible to use dotted notation to group by the child
+       attribute of another attribute.
+    """
+    expr = make_attrgetter(environment, attribute)
+    return [_GroupTuple(key, list(values)) for key, values
+            in groupby(sorted(value, key=expr), expr)]
+
+
+@environmentfilter
+def do_sum(environment, iterable, attribute=None, start=0):
+    """Returns the sum of a sequence of numbers plus the value of parameter
+    'start' (which defaults to 0).  When the sequence is empty it returns
+    start.
+
+    It is also possible to sum up only certain attributes:
+
+    .. sourcecode:: jinja
+
+        Total: {{ items|sum(attribute='price') }}
+
+    .. versionchanged:: 2.6
+       The `attribute` parameter was added to allow suming up over
+       attributes.  Also the `start` parameter was moved on to the right.
+    """
+    if attribute is not None:
+        iterable = imap(make_attrgetter(environment, attribute), iterable)
+    return sum(iterable, start)
+
+
+def do_list(value):
+    """Convert the value into a list.  If it was a string the returned list
+    will be a list of characters.
+    """
+    return list(value)
+
+
+def do_mark_safe(value):
+    """Mark the value as safe which means that in an environment with automatic
+    escaping enabled this variable will not be escaped.
+    """
+    return Markup(value)
+
+
+def do_mark_unsafe(value):
+    """Mark a value as unsafe.  This is the reverse operation for :func:`safe`."""
+    return text_type(value)
+
+
+def do_reverse(value):
+    """Reverse the object or return an iterator that iterates over it the other
+    way round.
+    """
+    if isinstance(value, string_types):
+        return value[::-1]
+    try:
+        return reversed(value)
+    except TypeError:
+        try:
+            rv = list(value)
+            rv.reverse()
+            return rv
+        except TypeError:
+            raise FilterArgumentError('argument must be iterable')
+
+
+@environmentfilter
+def do_attr(environment, obj, name):
+    """Get an attribute of an object.  ``foo|attr("bar")`` works like
+    ``foo.bar`` just that always an attribute is returned and items are not
+    looked up.
+
+    See :ref:`Notes on subscriptions <notes-on-subscriptions>` for more details.
+    """
+    try:
+        name = str(name)
+    except UnicodeError:
+        pass
+    else:
+        try:
+            value = getattr(obj, name)
+        except AttributeError:
+            pass
+        else:
+            if environment.sandboxed and not \
+               environment.is_safe_attribute(obj, name, value):
+                return environment.unsafe_undefined(obj, name)
+            return value
+    return environment.undefined(obj=obj, name=name)
+
+
+@contextfilter
+def do_map(*args, **kwargs):
+    """Applies a filter on a sequence of objects or looks up an attribute.
+    This is useful when dealing with lists of objects but you are really
+    only interested in a certain value of it.
+
+    The basic usage is mapping on an attribute.  Imagine you have a list
+    of users but you are only interested in a list of usernames:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ users|map(attribute='username')|join(', ') }}
+
+    Alternatively you can let it invoke a filter by passing the name of the
+    filter and the arguments afterwards.  A good example would be applying a
+    text conversion filter on a sequence:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ titles|map('lower')|join(', ') }}
+
+    .. versionadded:: 2.7
+    """
+    seq, func = prepare_map(args, kwargs)
+    if seq:
+        for item in seq:
+            yield func(item)
+
+
+@contextfilter
+def do_select(*args, **kwargs):
+    """Filters a sequence of objects by applying a test to each object,
+    and only selecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|select("odd") }}
+        {{ numbers|select("odd") }}
+        {{ numbers|select("divisibleby", 3) }}
+        {{ numbers|select("lessthan", 42) }}
+        {{ strings|select("equalto", "mystring") }}
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(args, kwargs, lambda x: x, False)
+
+
+@contextfilter
+def do_reject(*args, **kwargs):
+    """Filters a sequence of objects by applying a test to each object,
+    and rejecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|reject("odd") }}
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(args, kwargs, lambda x: not x, False)
+
+
+@contextfilter
+def do_selectattr(*args, **kwargs):
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and only selecting the objects with the
+    test succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ users|selectattr("is_active") }}
+        {{ users|selectattr("email", "none") }}
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(args, kwargs, lambda x: x, True)
+
+
+@contextfilter
+def do_rejectattr(*args, **kwargs):
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and rejecting the objects with the test
+    succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    .. sourcecode:: jinja
+
+        {{ users|rejectattr("is_active") }}
+        {{ users|rejectattr("email", "none") }}
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(args, kwargs, lambda x: not x, True)
+
+
+@evalcontextfilter
+def do_tojson(eval_ctx, value, indent=None):
+    """Dumps a structure to JSON so that it's safe to use in ``<script>``
+    tags.  It accepts the same arguments and returns a JSON string.  Note that
+    this is available in templates through the ``|tojson`` filter which will
+    also mark the result as safe.  Due to how this function escapes certain
+    characters this is safe even if used outside of ``<script>`` tags.
+
+    The following characters are escaped in strings:
+
+    -   ``<``
+    -   ``>``
+    -   ``&``
+    -   ``'``
+
+    This makes it safe to embed such strings in any place in HTML with the
+    notable exception of double quoted attributes.  In that case single
+    quote your attributes or HTML escape it in addition.
+
+    The indent parameter can be used to enable pretty printing.  Set it to
+    the number of spaces that the structures should be indented with.
+
+    Note that this filter is for use in HTML contexts only.
+
+    .. versionadded:: 2.9
+    """
+    policies = eval_ctx.environment.policies
+    dumper = policies['json.dumps_function']
+    options = policies['json.dumps_kwargs']
+    if indent is not None:
+        options = dict(options)
+        options['indent'] = indent
+    return htmlsafe_json_dumps(value, dumper=dumper, **options)
+
+
+def prepare_map(args, kwargs):
+    context = args[0]
+    seq = args[1]
+
+    if len(args) == 2 and 'attribute' in kwargs:
+        attribute = kwargs.pop('attribute')
+        if kwargs:
+            raise FilterArgumentError('Unexpected keyword argument %r' %
+                next(iter(kwargs)))
+        func = make_attrgetter(context.environment, attribute)
+    else:
+        try:
+            name = args[2]
+            args = args[3:]
+        except LookupError:
+            raise FilterArgumentError('map requires a filter argument')
+        func = lambda item: context.environment.call_filter(
+            name, item, args, kwargs, context=context)
+
+    return seq, func
+
+
+def prepare_select_or_reject(args, kwargs, modfunc, lookup_attr):
+    context = args[0]
+    seq = args[1]
+    if lookup_attr:
+        try:
+            attr = args[2]
+        except LookupError:
+            raise FilterArgumentError('Missing parameter for attribute name')
+        transfunc = make_attrgetter(context.environment, attr)
+        off = 1
+    else:
+        off = 0
+        transfunc = lambda x: x
+
+    try:
+        name = args[2 + off]
+        args = args[3 + off:]
+        func = lambda item: context.environment.call_test(
+            name, item, args, kwargs)
+    except LookupError:
+        func = bool
+
+    return seq, lambda item: modfunc(func(transfunc(item)))
+
+
+def select_or_reject(args, kwargs, modfunc, lookup_attr):
+    seq, func = prepare_select_or_reject(args, kwargs, modfunc, lookup_attr)
+    if seq:
+        for item in seq:
+            if func(item):
+                yield item
+
+
+FILTERS = {
+    'abs':                  abs,
+    'attr':                 do_attr,
+    'batch':                do_batch,
+    'capitalize':           do_capitalize,
+    'center':               do_center,
+    'count':                len,
+    'd':                    do_default,
+    'default':              do_default,
+    'dictsort':             do_dictsort,
+    'e':                    escape,
+    'escape':               escape,
+    'filesizeformat':       do_filesizeformat,
+    'first':                do_first,
+    'float':                do_float,
+    'forceescape':          do_forceescape,
+    'format':               do_format,
+    'groupby':              do_groupby,
+    'indent':               do_indent,
+    'int':                  do_int,
+    'join':                 do_join,
+    'last':                 do_last,
+    'length':               len,
+    'list':                 do_list,
+    'lower':                do_lower,
+    'map':                  do_map,
+    'min':                  do_min,
+    'max':                  do_max,
+    'pprint':               do_pprint,
+    'random':               do_random,
+    'reject':               do_reject,
+    'rejectattr':           do_rejectattr,
+    'replace':              do_replace,
+    'reverse':              do_reverse,
+    'round':                do_round,
+    'safe':                 do_mark_safe,
+    'select':               do_select,
+    'selectattr':           do_selectattr,
+    'slice':                do_slice,
+    'sort':                 do_sort,
+    'string':               soft_unicode,
+    'striptags':            do_striptags,
+    'sum':                  do_sum,
+    'title':                do_title,
+    'trim':                 do_trim,
+    'truncate':             do_truncate,
+    'unique':               do_unique,
+    'upper':                do_upper,
+    'urlencode':            do_urlencode,
+    'urlize':               do_urlize,
+    'wordcount':            do_wordcount,
+    'wordwrap':             do_wordwrap,
+    'xmlattr':              do_xmlattr,
+    'tojson':               do_tojson,
+}
diff --git a/python/jinja2/idtracking.py b/python/jinja2/idtracking.py
new file mode 100644
index 0000000..491bfe0
--- /dev/null
+++ b/python/jinja2/idtracking.py
@@ -0,0 +1,286 @@
+from jinja2.visitor import NodeVisitor
+from jinja2._compat import iteritems
+
+
+VAR_LOAD_PARAMETER = 'param'
+VAR_LOAD_RESOLVE = 'resolve'
+VAR_LOAD_ALIAS = 'alias'
+VAR_LOAD_UNDEFINED = 'undefined'
+
+
+def find_symbols(nodes, parent_symbols=None):
+    sym = Symbols(parent=parent_symbols)
+    visitor = FrameSymbolVisitor(sym)
+    for node in nodes:
+        visitor.visit(node)
+    return sym
+
+
+def symbols_for_node(node, parent_symbols=None):
+    sym = Symbols(parent=parent_symbols)
+    sym.analyze_node(node)
+    return sym
+
+
+class Symbols(object):
+
+    def __init__(self, parent=None, level=None):
+        if level is None:
+            if parent is None:
+                level = 0
+            else:
+                level = parent.level + 1
+        self.level = level
+        self.parent = parent
+        self.refs = {}
+        self.loads = {}
+        self.stores = set()
+
+    def analyze_node(self, node, **kwargs):
+        visitor = RootVisitor(self)
+        visitor.visit(node, **kwargs)
+
+    def _define_ref(self, name, load=None):
+        ident = 'l_%d_%s' % (self.level, name)
+        self.refs[name] = ident
+        if load is not None:
+            self.loads[ident] = load
+        return ident
+
+    def find_load(self, target):
+        if target in self.loads:
+            return self.loads[target]
+        if self.parent is not None:
+            return self.parent.find_load(target)
+
+    def find_ref(self, name):
+        if name in self.refs:
+            return self.refs[name]
+        if self.parent is not None:
+            return self.parent.find_ref(name)
+
+    def ref(self, name):
+        rv = self.find_ref(name)
+        if rv is None:
+            raise AssertionError('Tried to resolve a name to a reference that '
+                                 'was unknown to the frame (%r)' % name)
+        return rv
+
+    def copy(self):
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.refs = self.refs.copy()
+        rv.loads = self.loads.copy()
+        rv.stores = self.stores.copy()
+        return rv
+
+    def store(self, name):
+        self.stores.add(name)
+
+        # If we have not see the name referenced yet, we need to figure
+        # out what to set it to.
+        if name not in self.refs:
+            # If there is a parent scope we check if the name has a
+            # reference there.  If it does it means we might have to alias
+            # to a variable there.
+            if self.parent is not None:
+                outer_ref = self.parent.find_ref(name)
+                if outer_ref is not None:
+                    self._define_ref(name, load=(VAR_LOAD_ALIAS, outer_ref))
+                    return
+
+            # Otherwise we can just set it to undefined.
+            self._define_ref(name, load=(VAR_LOAD_UNDEFINED, None))
+
+    def declare_parameter(self, name):
+        self.stores.add(name)
+        return self._define_ref(name, load=(VAR_LOAD_PARAMETER, None))
+
+    def load(self, name):
+        target = self.find_ref(name)
+        if target is None:
+            self._define_ref(name, load=(VAR_LOAD_RESOLVE, name))
+
+    def branch_update(self, branch_symbols):
+        stores = {}
+        for branch in branch_symbols:
+            for target in branch.stores:
+                if target in self.stores:
+                    continue
+                stores[target] = stores.get(target, 0) + 1
+
+        for sym in branch_symbols:
+            self.refs.update(sym.refs)
+            self.loads.update(sym.loads)
+            self.stores.update(sym.stores)
+
+        for name, branch_count in iteritems(stores):
+            if branch_count == len(branch_symbols):
+                continue
+            target = self.find_ref(name)
+            assert target is not None, 'should not happen'
+
+            if self.parent is not None:
+                outer_target = self.parent.find_ref(name)
+                if outer_target is not None:
+                    self.loads[target] = (VAR_LOAD_ALIAS, outer_target)
+                    continue
+            self.loads[target] = (VAR_LOAD_RESOLVE, name)
+
+    def dump_stores(self):
+        rv = {}
+        node = self
+        while node is not None:
+            for name in node.stores:
+                if name not in rv:
+                    rv[name] = self.find_ref(name)
+            node = node.parent
+        return rv
+
+    def dump_param_targets(self):
+        rv = set()
+        node = self
+        while node is not None:
+            for target, (instr, _) in iteritems(self.loads):
+                if instr == VAR_LOAD_PARAMETER:
+                    rv.add(target)
+            node = node.parent
+        return rv
+
+
+class RootVisitor(NodeVisitor):
+
+    def __init__(self, symbols):
+        self.sym_visitor = FrameSymbolVisitor(symbols)
+
+    def _simple_visit(self, node, **kwargs):
+        for child in node.iter_child_nodes():
+            self.sym_visitor.visit(child)
+
+    visit_Template = visit_Block = visit_Macro = visit_FilterBlock = \
+        visit_Scope = visit_If = visit_ScopedEvalContextModifier = \
+        _simple_visit
+
+    def visit_AssignBlock(self, node, **kwargs):
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_CallBlock(self, node, **kwargs):
+        for child in node.iter_child_nodes(exclude=('call',)):
+            self.sym_visitor.visit(child)
+
+    def visit_OverlayScope(self, node, **kwargs):
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_For(self, node, for_branch='body', **kwargs):
+        if for_branch == 'body':
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            branch = node.body
+        elif for_branch == 'else':
+            branch = node.else_
+        elif for_branch == 'test':
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            if node.test is not None:
+                self.sym_visitor.visit(node.test)
+            return
+        else:
+            raise RuntimeError('Unknown for branch')
+        for item in branch or ():
+            self.sym_visitor.visit(item)
+
+    def visit_With(self, node, **kwargs):
+        for target in node.targets:
+            self.sym_visitor.visit(target)
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def generic_visit(self, node, *args, **kwargs):
+        raise NotImplementedError('Cannot find symbols for %r' %
+                                  node.__class__.__name__)
+
+
+class FrameSymbolVisitor(NodeVisitor):
+    """A visitor for `Frame.inspect`."""
+
+    def __init__(self, symbols):
+        self.symbols = symbols
+
+    def visit_Name(self, node, store_as_param=False, **kwargs):
+        """All assignments to names go through this function."""
+        if store_as_param or node.ctx == 'param':
+            self.symbols.declare_parameter(node.name)
+        elif node.ctx == 'store':
+            self.symbols.store(node.name)
+        elif node.ctx == 'load':
+            self.symbols.load(node.name)
+
+    def visit_NSRef(self, node, **kwargs):
+        self.symbols.load(node.name)
+
+    def visit_If(self, node, **kwargs):
+        self.visit(node.test, **kwargs)
+
+        original_symbols = self.symbols
+
+        def inner_visit(nodes):
+            self.symbols = rv = original_symbols.copy()
+            for subnode in nodes:
+                self.visit(subnode, **kwargs)
+            self.symbols = original_symbols
+            return rv
+
+        body_symbols = inner_visit(node.body)
+        elif_symbols = inner_visit(node.elif_)
+        else_symbols = inner_visit(node.else_ or ())
+
+        self.symbols.branch_update([body_symbols, elif_symbols, else_symbols])
+
+    def visit_Macro(self, node, **kwargs):
+        self.symbols.store(node.name)
+
+    def visit_Import(self, node, **kwargs):
+        self.generic_visit(node, **kwargs)
+        self.symbols.store(node.target)
+
+    def visit_FromImport(self, node, **kwargs):
+        self.generic_visit(node, **kwargs)
+        for name in node.names:
+            if isinstance(name, tuple):
+                self.symbols.store(name[1])
+            else:
+                self.symbols.store(name)
+
+    def visit_Assign(self, node, **kwargs):
+        """Visit assignments in the correct order."""
+        self.visit(node.node, **kwargs)
+        self.visit(node.target, **kwargs)
+
+    def visit_For(self, node, **kwargs):
+        """Visiting stops at for blocks.  However the block sequence
+        is visited as part of the outer scope.
+        """
+        self.visit(node.iter, **kwargs)
+
+    def visit_CallBlock(self, node, **kwargs):
+        self.visit(node.call, **kwargs)
+
+    def visit_FilterBlock(self, node, **kwargs):
+        self.visit(node.filter, **kwargs)
+
+    def visit_With(self, node, **kwargs):
+        for target in node.values:
+            self.visit(target)
+
+    def visit_AssignBlock(self, node, **kwargs):
+        """Stop visiting at block assigns."""
+        self.visit(node.target, **kwargs)
+
+    def visit_Scope(self, node, **kwargs):
+        """Stop visiting at scopes."""
+
+    def visit_Block(self, node, **kwargs):
+        """Stop visiting at blocks."""
+
+    def visit_OverlayScope(self, node, **kwargs):
+        """Do not visit into overlay scopes."""
diff --git a/python/jinja2/lexer.py b/python/jinja2/lexer.py
new file mode 100644
index 0000000..6fd135d
--- /dev/null
+++ b/python/jinja2/lexer.py
@@ -0,0 +1,739 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.lexer
+    ~~~~~~~~~~~~
+
+    This module implements a Jinja / Python combination lexer. The
+    `Lexer` class provided by this module is used to do some preprocessing
+    for Jinja.
+
+    On the one hand it filters out invalid operators like the bitshift
+    operators we don't allow in templates. On the other hand it separates
+    template code and python code in expressions.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import re
+from collections import deque
+from operator import itemgetter
+
+from jinja2._compat import implements_iterator, intern, iteritems, text_type
+from jinja2.exceptions import TemplateSyntaxError
+from jinja2.utils import LRUCache
+
+# cache for the lexers. Exists in order to be able to have multiple
+# environments with the same lexer
+_lexer_cache = LRUCache(50)
+
+# static regular expressions
+whitespace_re = re.compile(r'\s+', re.U)
+string_re = re.compile(r"('([^'\\]*(?:\\.[^'\\]*)*)'"
+                       r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S)
+integer_re = re.compile(r'\d+')
+
+try:
+    # check if this Python supports Unicode identifiers
+    compile('föö', '<unknown>', 'eval')
+except SyntaxError:
+    # no Unicode support, use ASCII identifiers
+    name_re = re.compile(r'[a-zA-Z_][a-zA-Z0-9_]*')
+    check_ident = False
+else:
+    # Unicode support, build a pattern to match valid characters, and set flag
+    # to use str.isidentifier to validate during lexing
+    from jinja2 import _identifier
+    name_re = re.compile(r'[\w{0}]+'.format(_identifier.pattern))
+    check_ident = True
+    # remove the pattern from memory after building the regex
+    import sys
+    del sys.modules['jinja2._identifier']
+    import jinja2
+    del jinja2._identifier
+    del _identifier
+
+float_re = re.compile(r'(?<!\.)\d+\.\d+')
+newline_re = re.compile(r'(\r\n|\r|\n)')
+
+# internal the tokens and keep references to them
+TOKEN_ADD = intern('add')
+TOKEN_ASSIGN = intern('assign')
+TOKEN_COLON = intern('colon')
+TOKEN_COMMA = intern('comma')
+TOKEN_DIV = intern('div')
+TOKEN_DOT = intern('dot')
+TOKEN_EQ = intern('eq')
+TOKEN_FLOORDIV = intern('floordiv')
+TOKEN_GT = intern('gt')
+TOKEN_GTEQ = intern('gteq')
+TOKEN_LBRACE = intern('lbrace')
+TOKEN_LBRACKET = intern('lbracket')
+TOKEN_LPAREN = intern('lparen')
+TOKEN_LT = intern('lt')
+TOKEN_LTEQ = intern('lteq')
+TOKEN_MOD = intern('mod')
+TOKEN_MUL = intern('mul')
+TOKEN_NE = intern('ne')
+TOKEN_PIPE = intern('pipe')
+TOKEN_POW = intern('pow')
+TOKEN_RBRACE = intern('rbrace')
+TOKEN_RBRACKET = intern('rbracket')
+TOKEN_RPAREN = intern('rparen')
+TOKEN_SEMICOLON = intern('semicolon')
+TOKEN_SUB = intern('sub')
+TOKEN_TILDE = intern('tilde')
+TOKEN_WHITESPACE = intern('whitespace')
+TOKEN_FLOAT = intern('float')
+TOKEN_INTEGER = intern('integer')
+TOKEN_NAME = intern('name')
+TOKEN_STRING = intern('string')
+TOKEN_OPERATOR = intern('operator')
+TOKEN_BLOCK_BEGIN = intern('block_begin')
+TOKEN_BLOCK_END = intern('block_end')
+TOKEN_VARIABLE_BEGIN = intern('variable_begin')
+TOKEN_VARIABLE_END = intern('variable_end')
+TOKEN_RAW_BEGIN = intern('raw_begin')
+TOKEN_RAW_END = intern('raw_end')
+TOKEN_COMMENT_BEGIN = intern('comment_begin')
+TOKEN_COMMENT_END = intern('comment_end')
+TOKEN_COMMENT = intern('comment')
+TOKEN_LINESTATEMENT_BEGIN = intern('linestatement_begin')
+TOKEN_LINESTATEMENT_END = intern('linestatement_end')
+TOKEN_LINECOMMENT_BEGIN = intern('linecomment_begin')
+TOKEN_LINECOMMENT_END = intern('linecomment_end')
+TOKEN_LINECOMMENT = intern('linecomment')
+TOKEN_DATA = intern('data')
+TOKEN_INITIAL = intern('initial')
+TOKEN_EOF = intern('eof')
+
+# bind operators to token types
+operators = {
+    '+':            TOKEN_ADD,
+    '-':            TOKEN_SUB,
+    '/':            TOKEN_DIV,
+    '//':           TOKEN_FLOORDIV,
+    '*':            TOKEN_MUL,
+    '%':            TOKEN_MOD,
+    '**':           TOKEN_POW,
+    '~':            TOKEN_TILDE,
+    '[':            TOKEN_LBRACKET,
+    ']':            TOKEN_RBRACKET,
+    '(':            TOKEN_LPAREN,
+    ')':            TOKEN_RPAREN,
+    '{':            TOKEN_LBRACE,
+    '}':            TOKEN_RBRACE,
+    '==':           TOKEN_EQ,
+    '!=':           TOKEN_NE,
+    '>':            TOKEN_GT,
+    '>=':           TOKEN_GTEQ,
+    '<':            TOKEN_LT,
+    '<=':           TOKEN_LTEQ,
+    '=':            TOKEN_ASSIGN,
+    '.':            TOKEN_DOT,
+    ':':            TOKEN_COLON,
+    '|':            TOKEN_PIPE,
+    ',':            TOKEN_COMMA,
+    ';':            TOKEN_SEMICOLON
+}
+
+reverse_operators = dict([(v, k) for k, v in iteritems(operators)])
+assert len(operators) == len(reverse_operators), 'operators dropped'
+operator_re = re.compile('(%s)' % '|'.join(re.escape(x) for x in
+                         sorted(operators, key=lambda x: -len(x))))
+
+ignored_tokens = frozenset([TOKEN_COMMENT_BEGIN, TOKEN_COMMENT,
+                            TOKEN_COMMENT_END, TOKEN_WHITESPACE,
+                            TOKEN_LINECOMMENT_BEGIN, TOKEN_LINECOMMENT_END,
+                            TOKEN_LINECOMMENT])
+ignore_if_empty = frozenset([TOKEN_WHITESPACE, TOKEN_DATA,
+                             TOKEN_COMMENT, TOKEN_LINECOMMENT])
+
+
+def _describe_token_type(token_type):
+    if token_type in reverse_operators:
+        return reverse_operators[token_type]
+    return {
+        TOKEN_COMMENT_BEGIN:        'begin of comment',
+        TOKEN_COMMENT_END:          'end of comment',
+        TOKEN_COMMENT:              'comment',
+        TOKEN_LINECOMMENT:          'comment',
+        TOKEN_BLOCK_BEGIN:          'begin of statement block',
+        TOKEN_BLOCK_END:            'end of statement block',
+        TOKEN_VARIABLE_BEGIN:       'begin of print statement',
+        TOKEN_VARIABLE_END:         'end of print statement',
+        TOKEN_LINESTATEMENT_BEGIN:  'begin of line statement',
+        TOKEN_LINESTATEMENT_END:    'end of line statement',
+        TOKEN_DATA:                 'template data / text',
+        TOKEN_EOF:                  'end of template'
+    }.get(token_type, token_type)
+
+
+def describe_token(token):
+    """Returns a description of the token."""
+    if token.type == 'name':
+        return token.value
+    return _describe_token_type(token.type)
+
+
+def describe_token_expr(expr):
+    """Like `describe_token` but for token expressions."""
+    if ':' in expr:
+        type, value = expr.split(':', 1)
+        if type == 'name':
+            return value
+    else:
+        type = expr
+    return _describe_token_type(type)
+
+
+def count_newlines(value):
+    """Count the number of newline characters in the string.  This is
+    useful for extensions that filter a stream.
+    """
+    return len(newline_re.findall(value))
+
+
+def compile_rules(environment):
+    """Compiles all the rules from the environment into a list of rules."""
+    e = re.escape
+    rules = [
+        (len(environment.comment_start_string), 'comment',
+         e(environment.comment_start_string)),
+        (len(environment.block_start_string), 'block',
+         e(environment.block_start_string)),
+        (len(environment.variable_start_string), 'variable',
+         e(environment.variable_start_string))
+    ]
+
+    if environment.line_statement_prefix is not None:
+        rules.append((len(environment.line_statement_prefix), 'linestatement',
+                      r'^[ \t\v]*' + e(environment.line_statement_prefix)))
+    if environment.line_comment_prefix is not None:
+        rules.append((len(environment.line_comment_prefix), 'linecomment',
+                      r'(?:^|(?<=\S))[^\S\r\n]*' +
+                      e(environment.line_comment_prefix)))
+
+    return [x[1:] for x in sorted(rules, reverse=True)]
+
+
+class Failure(object):
+    """Class that raises a `TemplateSyntaxError` if called.
+    Used by the `Lexer` to specify known errors.
+    """
+
+    def __init__(self, message, cls=TemplateSyntaxError):
+        self.message = message
+        self.error_class = cls
+
+    def __call__(self, lineno, filename):
+        raise self.error_class(self.message, lineno, filename)
+
+
+class Token(tuple):
+    """Token class."""
+    __slots__ = ()
+    lineno, type, value = (property(itemgetter(x)) for x in range(3))
+
+    def __new__(cls, lineno, type, value):
+        return tuple.__new__(cls, (lineno, intern(str(type)), value))
+
+    def __str__(self):
+        if self.type in reverse_operators:
+            return reverse_operators[self.type]
+        elif self.type == 'name':
+            return self.value
+        return self.type
+
+    def test(self, expr):
+        """Test a token against a token expression.  This can either be a
+        token type or ``'token_type:token_value'``.  This can only test
+        against string values and types.
+        """
+        # here we do a regular string equality check as test_any is usually
+        # passed an iterable of not interned strings.
+        if self.type == expr:
+            return True
+        elif ':' in expr:
+            return expr.split(':', 1) == [self.type, self.value]
+        return False
+
+    def test_any(self, *iterable):
+        """Test against multiple token expressions."""
+        for expr in iterable:
+            if self.test(expr):
+                return True
+        return False
+
+    def __repr__(self):
+        return 'Token(%r, %r, %r)' % (
+            self.lineno,
+            self.type,
+            self.value
+        )
+
+
+@implements_iterator
+class TokenStreamIterator(object):
+    """The iterator for tokenstreams.  Iterate over the stream
+    until the eof token is reached.
+    """
+
+    def __init__(self, stream):
+        self.stream = stream
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        token = self.stream.current
+        if token.type is TOKEN_EOF:
+            self.stream.close()
+            raise StopIteration()
+        next(self.stream)
+        return token
+
+
+@implements_iterator
+class TokenStream(object):
+    """A token stream is an iterable that yields :class:`Token`\\s.  The
+    parser however does not iterate over it but calls :meth:`next` to go
+    one token ahead.  The current active token is stored as :attr:`current`.
+    """
+
+    def __init__(self, generator, name, filename):
+        self._iter = iter(generator)
+        self._pushed = deque()
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.current = Token(1, TOKEN_INITIAL, '')
+        next(self)
+
+    def __iter__(self):
+        return TokenStreamIterator(self)
+
+    def __bool__(self):
+        return bool(self._pushed) or self.current.type is not TOKEN_EOF
+    __nonzero__ = __bool__  # py2
+
+    eos = property(lambda x: not x, doc="Are we at the end of the stream?")
+
+    def push(self, token):
+        """Push a token back to the stream."""
+        self._pushed.append(token)
+
+    def look(self):
+        """Look at the next token."""
+        old_token = next(self)
+        result = self.current
+        self.push(result)
+        self.current = old_token
+        return result
+
+    def skip(self, n=1):
+        """Got n tokens ahead."""
+        for x in range(n):
+            next(self)
+
+    def next_if(self, expr):
+        """Perform the token test and return the token if it matched.
+        Otherwise the return value is `None`.
+        """
+        if self.current.test(expr):
+            return next(self)
+
+    def skip_if(self, expr):
+        """Like :meth:`next_if` but only returns `True` or `False`."""
+        return self.next_if(expr) is not None
+
+    def __next__(self):
+        """Go one token ahead and return the old one.
+
+        Use the built-in :func:`next` instead of calling this directly.
+        """
+        rv = self.current
+        if self._pushed:
+            self.current = self._pushed.popleft()
+        elif self.current.type is not TOKEN_EOF:
+            try:
+                self.current = next(self._iter)
+            except StopIteration:
+                self.close()
+        return rv
+
+    def close(self):
+        """Close the stream."""
+        self.current = Token(self.current.lineno, TOKEN_EOF, '')
+        self._iter = None
+        self.closed = True
+
+    def expect(self, expr):
+        """Expect a given token type and return it.  This accepts the same
+        argument as :meth:`jinja2.lexer.Token.test`.
+        """
+        if not self.current.test(expr):
+            expr = describe_token_expr(expr)
+            if self.current.type is TOKEN_EOF:
+                raise TemplateSyntaxError('unexpected end of template, '
+                                          'expected %r.' % expr,
+                                          self.current.lineno,
+                                          self.name, self.filename)
+            raise TemplateSyntaxError("expected token %r, got %r" %
+                                      (expr, describe_token(self.current)),
+                                      self.current.lineno,
+                                      self.name, self.filename)
+        try:
+            return self.current
+        finally:
+            next(self)
+
+
+def get_lexer(environment):
+    """Return a lexer which is probably cached."""
+    key = (environment.block_start_string,
+           environment.block_end_string,
+           environment.variable_start_string,
+           environment.variable_end_string,
+           environment.comment_start_string,
+           environment.comment_end_string,
+           environment.line_statement_prefix,
+           environment.line_comment_prefix,
+           environment.trim_blocks,
+           environment.lstrip_blocks,
+           environment.newline_sequence,
+           environment.keep_trailing_newline)
+    lexer = _lexer_cache.get(key)
+    if lexer is None:
+        lexer = Lexer(environment)
+        _lexer_cache[key] = lexer
+    return lexer
+
+
+class Lexer(object):
+    """Class that implements a lexer for a given environment. Automatically
+    created by the environment class, usually you don't have to do that.
+
+    Note that the lexer is not automatically bound to an environment.
+    Multiple environments can share the same lexer.
+    """
+
+    def __init__(self, environment):
+        # shortcuts
+        c = lambda x: re.compile(x, re.M | re.S)
+        e = re.escape
+
+        # lexing rules for tags
+        tag_rules = [
+            (whitespace_re, TOKEN_WHITESPACE, None),
+            (float_re, TOKEN_FLOAT, None),
+            (integer_re, TOKEN_INTEGER, None),
+            (name_re, TOKEN_NAME, None),
+            (string_re, TOKEN_STRING, None),
+            (operator_re, TOKEN_OPERATOR, None)
+        ]
+
+        # assemble the root lexing rule. because "|" is ungreedy
+        # we have to sort by length so that the lexer continues working
+        # as expected when we have parsing rules like <% for block and
+        # <%= for variables. (if someone wants asp like syntax)
+        # variables are just part of the rules if variable processing
+        # is required.
+        root_tag_rules = compile_rules(environment)
+
+        # block suffix if trimming is enabled
+        block_suffix_re = environment.trim_blocks and '\\n?' or ''
+
+        # strip leading spaces if lstrip_blocks is enabled
+        prefix_re = {}
+        if environment.lstrip_blocks:
+            # use '{%+' to manually disable lstrip_blocks behavior
+            no_lstrip_re = e('+')
+            # detect overlap between block and variable or comment strings
+            block_diff = c(r'^%s(.*)' % e(environment.block_start_string))
+            # make sure we don't mistake a block for a variable or a comment
+            m = block_diff.match(environment.comment_start_string)
+            no_lstrip_re += m and r'|%s' % e(m.group(1)) or ''
+            m = block_diff.match(environment.variable_start_string)
+            no_lstrip_re += m and r'|%s' % e(m.group(1)) or ''
+
+            # detect overlap between comment and variable strings
+            comment_diff = c(r'^%s(.*)' % e(environment.comment_start_string))
+            m = comment_diff.match(environment.variable_start_string)
+            no_variable_re = m and r'(?!%s)' % e(m.group(1)) or ''
+
+            lstrip_re = r'^[ \t]*'
+            block_prefix_re = r'%s%s(?!%s)|%s\+?' % (
+                    lstrip_re,
+                    e(environment.block_start_string),
+                    no_lstrip_re,
+                    e(environment.block_start_string),
+                    )
+            comment_prefix_re = r'%s%s%s|%s\+?' % (
+                    lstrip_re,
+                    e(environment.comment_start_string),
+                    no_variable_re,
+                    e(environment.comment_start_string),
+                    )
+            prefix_re['block'] = block_prefix_re
+            prefix_re['comment'] = comment_prefix_re
+        else:
+            block_prefix_re = '%s' % e(environment.block_start_string)
+
+        self.newline_sequence = environment.newline_sequence
+        self.keep_trailing_newline = environment.keep_trailing_newline
+
+        # global lexing rules
+        self.rules = {
+            'root': [
+                # directives
+                (c('(.*?)(?:%s)' % '|'.join(
+                    [r'(?P<raw_begin>(?:\s*%s\-|%s)\s*raw\s*(?:\-%s\s*|%s))' % (
+                        e(environment.block_start_string),
+                        block_prefix_re,
+                        e(environment.block_end_string),
+                        e(environment.block_end_string)
+                    )] + [
+                        r'(?P<%s_begin>\s*%s\-|%s)' % (n, r, prefix_re.get(n,r))
+                        for n, r in root_tag_rules
+                    ])), (TOKEN_DATA, '#bygroup'), '#bygroup'),
+                # data
+                (c('.+'), TOKEN_DATA, None)
+            ],
+            # comments
+            TOKEN_COMMENT_BEGIN: [
+                (c(r'(.*?)((?:\-%s\s*|%s)%s)' % (
+                    e(environment.comment_end_string),
+                    e(environment.comment_end_string),
+                    block_suffix_re
+                )), (TOKEN_COMMENT, TOKEN_COMMENT_END), '#pop'),
+                (c('(.)'), (Failure('Missing end of comment tag'),), None)
+            ],
+            # blocks
+            TOKEN_BLOCK_BEGIN: [
+                (c(r'(?:\-%s\s*|%s)%s' % (
+                    e(environment.block_end_string),
+                    e(environment.block_end_string),
+                    block_suffix_re
+                )), TOKEN_BLOCK_END, '#pop'),
+            ] + tag_rules,
+            # variables
+            TOKEN_VARIABLE_BEGIN: [
+                (c(r'\-%s\s*|%s' % (
+                    e(environment.variable_end_string),
+                    e(environment.variable_end_string)
+                )), TOKEN_VARIABLE_END, '#pop')
+            ] + tag_rules,
+            # raw block
+            TOKEN_RAW_BEGIN: [
+                (c(r'(.*?)((?:\s*%s\-|%s)\s*endraw\s*(?:\-%s\s*|%s%s))' % (
+                    e(environment.block_start_string),
+                    block_prefix_re,
+                    e(environment.block_end_string),
+                    e(environment.block_end_string),
+                    block_suffix_re
+                )), (TOKEN_DATA, TOKEN_RAW_END), '#pop'),
+                (c('(.)'), (Failure('Missing end of raw directive'),), None)
+            ],
+            # line statements
+            TOKEN_LINESTATEMENT_BEGIN: [
+                (c(r'\s*(\n|$)'), TOKEN_LINESTATEMENT_END, '#pop')
+            ] + tag_rules,
+            # line comments
+            TOKEN_LINECOMMENT_BEGIN: [
+                (c(r'(.*?)()(?=\n|$)'), (TOKEN_LINECOMMENT,
+                 TOKEN_LINECOMMENT_END), '#pop')
+            ]
+        }
+
+    def _normalize_newlines(self, value):
+        """Called for strings and template data to normalize it to unicode."""
+        return newline_re.sub(self.newline_sequence, value)
+
+    def tokenize(self, source, name=None, filename=None, state=None):
+        """Calls tokeniter + tokenize and wraps it in a token stream.
+        """
+        stream = self.tokeniter(source, name, filename, state)
+        return TokenStream(self.wrap(stream, name, filename), name, filename)
+
+    def wrap(self, stream, name=None, filename=None):
+        """This is called with the stream as returned by `tokenize` and wraps
+        every token in a :class:`Token` and converts the value.
+        """
+        for lineno, token, value in stream:
+            if token in ignored_tokens:
+                continue
+            elif token == 'linestatement_begin':
+                token = 'block_begin'
+            elif token == 'linestatement_end':
+                token = 'block_end'
+            # we are not interested in those tokens in the parser
+            elif token in ('raw_begin', 'raw_end'):
+                continue
+            elif token == 'data':
+                value = self._normalize_newlines(value)
+            elif token == 'keyword':
+                token = value
+            elif token == 'name':
+                value = str(value)
+                if check_ident and not value.isidentifier():
+                    raise TemplateSyntaxError(
+                        'Invalid character in identifier',
+                        lineno, name, filename)
+            elif token == 'string':
+                # try to unescape string
+                try:
+                    value = self._normalize_newlines(value[1:-1]) \
+                        .encode('ascii', 'backslashreplace') \
+                        .decode('unicode-escape')
+                except Exception as e:
+                    msg = str(e).split(':')[-1].strip()
+                    raise TemplateSyntaxError(msg, lineno, name, filename)
+            elif token == 'integer':
+                value = int(value)
+            elif token == 'float':
+                value = float(value)
+            elif token == 'operator':
+                token = operators[value]
+            yield Token(lineno, token, value)
+
+    def tokeniter(self, source, name, filename=None, state=None):
+        """This method tokenizes the text and returns the tokens in a
+        generator.  Use this method if you just want to tokenize a template.
+        """
+        source = text_type(source)
+        lines = source.splitlines()
+        if self.keep_trailing_newline and source:
+            for newline in ('\r\n', '\r', '\n'):
+                if source.endswith(newline):
+                    lines.append('')
+                    break
+        source = '\n'.join(lines)
+        pos = 0
+        lineno = 1
+        stack = ['root']
+        if state is not None and state != 'root':
+            assert state in ('variable', 'block'), 'invalid state'
+            stack.append(state + '_begin')
+        else:
+            state = 'root'
+        statetokens = self.rules[stack[-1]]
+        source_length = len(source)
+
+        balancing_stack = []
+
+        while 1:
+            # tokenizer loop
+            for regex, tokens, new_state in statetokens:
+                m = regex.match(source, pos)
+                # if no match we try again with the next rule
+                if m is None:
+                    continue
+
+                # we only match blocks and variables if braces / parentheses
+                # are balanced. continue parsing with the lower rule which
+                # is the operator rule. do this only if the end tags look
+                # like operators
+                if balancing_stack and \
+                   tokens in ('variable_end', 'block_end',
+                              'linestatement_end'):
+                    continue
+
+                # tuples support more options
+                if isinstance(tokens, tuple):
+                    for idx, token in enumerate(tokens):
+                        # failure group
+                        if token.__class__ is Failure:
+                            raise token(lineno, filename)
+                        # bygroup is a bit more complex, in that case we
+                        # yield for the current token the first named
+                        # group that matched
+                        elif token == '#bygroup':
+                            for key, value in iteritems(m.groupdict()):
+                                if value is not None:
+                                    yield lineno, key, value
+                                    lineno += value.count('\n')
+                                    break
+                            else:
+                                raise RuntimeError('%r wanted to resolve '
+                                                   'the token dynamically'
+                                                   ' but no group matched'
+                                                   % regex)
+                        # normal group
+                        else:
+                            data = m.group(idx + 1)
+                            if data or token not in ignore_if_empty:
+                                yield lineno, token, data
+                            lineno += data.count('\n')
+
+                # strings as token just are yielded as it.
+                else:
+                    data = m.group()
+                    # update brace/parentheses balance
+                    if tokens == 'operator':
+                        if data == '{':
+                            balancing_stack.append('}')
+                        elif data == '(':
+                            balancing_stack.append(')')
+                        elif data == '[':
+                            balancing_stack.append(']')
+                        elif data in ('}', ')', ']'):
+                            if not balancing_stack:
+                                raise TemplateSyntaxError('unexpected \'%s\'' %
+                                                          data, lineno, name,
+                                                          filename)
+                            expected_op = balancing_stack.pop()
+                            if expected_op != data:
+                                raise TemplateSyntaxError('unexpected \'%s\', '
+                                                          'expected \'%s\'' %
+                                                          (data, expected_op),
+                                                          lineno, name,
+                                                          filename)
+                    # yield items
+                    if data or tokens not in ignore_if_empty:
+                        yield lineno, tokens, data
+                    lineno += data.count('\n')
+
+                # fetch new position into new variable so that we can check
+                # if there is a internal parsing error which would result
+                # in an infinite loop
+                pos2 = m.end()
+
+                # handle state changes
+                if new_state is not None:
+                    # remove the uppermost state
+                    if new_state == '#pop':
+                        stack.pop()
+                    # resolve the new state by group checking
+                    elif new_state == '#bygroup':
+                        for key, value in iteritems(m.groupdict()):
+                            if value is not None:
+                                stack.append(key)
+                                break
+                        else:
+                            raise RuntimeError('%r wanted to resolve the '
+                                               'new state dynamically but'
+                                               ' no group matched' %
+                                               regex)
+                    # direct state name given
+                    else:
+                        stack.append(new_state)
+                    statetokens = self.rules[stack[-1]]
+                # we are still at the same position and no stack change.
+                # this means a loop without break condition, avoid that and
+                # raise error
+                elif pos2 == pos:
+                    raise RuntimeError('%r yielded empty string without '
+                                       'stack change' % regex)
+                # publish new function and start again
+                pos = pos2
+                break
+            # if loop terminated without break we haven't found a single match
+            # either we are at the end of the file or we have a problem
+            else:
+                # end of text
+                if pos >= source_length:
+                    return
+                # something went wrong
+                raise TemplateSyntaxError('unexpected char %r at %d' %
+                                          (source[pos], pos), lineno,
+                                          name, filename)
diff --git a/python/jinja2/loaders.py b/python/jinja2/loaders.py
new file mode 100644
index 0000000..4c79793
--- /dev/null
+++ b/python/jinja2/loaders.py
@@ -0,0 +1,481 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.loaders
+    ~~~~~~~~~~~~~~
+
+    Jinja loader classes.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import os
+import sys
+import weakref
+from types import ModuleType
+from os import path
+from hashlib import sha1
+from jinja2.exceptions import TemplateNotFound
+from jinja2.utils import open_if_exists, internalcode
+from jinja2._compat import string_types, iteritems
+
+
+def split_template_path(template):
+    """Split a path into segments and perform a sanity check.  If it detects
+    '..' in the path it will raise a `TemplateNotFound` error.
+    """
+    pieces = []
+    for piece in template.split('/'):
+        if path.sep in piece \
+           or (path.altsep and path.altsep in piece) or \
+           piece == path.pardir:
+            raise TemplateNotFound(template)
+        elif piece and piece != '.':
+            pieces.append(piece)
+    return pieces
+
+
+class BaseLoader(object):
+    """Baseclass for all loaders.  Subclass this and override `get_source` to
+    implement a custom loading mechanism.  The environment provides a
+    `get_template` method that calls the loader's `load` method to get the
+    :class:`Template` object.
+
+    A very basic example for a loader that looks up templates on the file
+    system could look like this::
+
+        from jinja2 import BaseLoader, TemplateNotFound
+        from os.path import join, exists, getmtime
+
+        class MyLoader(BaseLoader):
+
+            def __init__(self, path):
+                self.path = path
+
+            def get_source(self, environment, template):
+                path = join(self.path, template)
+                if not exists(path):
+                    raise TemplateNotFound(template)
+                mtime = getmtime(path)
+                with file(path) as f:
+                    source = f.read().decode('utf-8')
+                return source, path, lambda: mtime == getmtime(path)
+    """
+
+    #: if set to `False` it indicates that the loader cannot provide access
+    #: to the source of templates.
+    #:
+    #: .. versionadded:: 2.4
+    has_source_access = True
+
+    def get_source(self, environment, template):
+        """Get the template source, filename and reload helper for a template.
+        It's passed the environment and template name and has to return a
+        tuple in the form ``(source, filename, uptodate)`` or raise a
+        `TemplateNotFound` error if it can't locate the template.
+
+        The source part of the returned tuple must be the source of the
+        template as unicode string or a ASCII bytestring.  The filename should
+        be the name of the file on the filesystem if it was loaded from there,
+        otherwise `None`.  The filename is used by python for the tracebacks
+        if no loader extension is used.
+
+        The last item in the tuple is the `uptodate` function.  If auto
+        reloading is enabled it's always called to check if the template
+        changed.  No arguments are passed so the function must store the
+        old state somewhere (for example in a closure).  If it returns `False`
+        the template will be reloaded.
+        """
+        if not self.has_source_access:
+            raise RuntimeError('%s cannot provide access to the source' %
+                               self.__class__.__name__)
+        raise TemplateNotFound(template)
+
+    def list_templates(self):
+        """Iterates over all templates.  If the loader does not support that
+        it should raise a :exc:`TypeError` which is the default behavior.
+        """
+        raise TypeError('this loader cannot iterate over all templates')
+
+    @internalcode
+    def load(self, environment, name, globals=None):
+        """Loads a template.  This method looks up the template in the cache
+        or loads one by calling :meth:`get_source`.  Subclasses should not
+        override this method as loaders working on collections of other
+        loaders (such as :class:`PrefixLoader` or :class:`ChoiceLoader`)
+        will not call this method but `get_source` directly.
+        """
+        code = None
+        if globals is None:
+            globals = {}
+
+        # first we try to get the source for this template together
+        # with the filename and the uptodate function.
+        source, filename, uptodate = self.get_source(environment, name)
+
+        # try to load the code from the bytecode cache if there is a
+        # bytecode cache configured.
+        bcc = environment.bytecode_cache
+        if bcc is not None:
+            bucket = bcc.get_bucket(environment, name, filename, source)
+            code = bucket.code
+
+        # if we don't have code so far (not cached, no longer up to
+        # date) etc. we compile the template
+        if code is None:
+            code = environment.compile(source, name, filename)
+
+        # if the bytecode cache is available and the bucket doesn't
+        # have a code so far, we give the bucket the new code and put
+        # it back to the bytecode cache.
+        if bcc is not None and bucket.code is None:
+            bucket.code = code
+            bcc.set_bucket(bucket)
+
+        return environment.template_class.from_code(environment, code,
+                                                    globals, uptodate)
+
+
+class FileSystemLoader(BaseLoader):
+    """Loads templates from the file system.  This loader can find templates
+    in folders on the file system and is the preferred way to load them.
+
+    The loader takes the path to the templates as string, or if multiple
+    locations are wanted a list of them which is then looked up in the
+    given order::
+
+    >>> loader = FileSystemLoader('/path/to/templates')
+    >>> loader = FileSystemLoader(['/path/to/templates', '/other/path'])
+
+    Per default the template encoding is ``'utf-8'`` which can be changed
+    by setting the `encoding` parameter to something else.
+
+    To follow symbolic links, set the *followlinks* parameter to ``True``::
+
+    >>> loader = FileSystemLoader('/path/to/templates', followlinks=True)
+
+    .. versionchanged:: 2.8+
+       The *followlinks* parameter was added.
+    """
+
+    def __init__(self, searchpath, encoding='utf-8', followlinks=False):
+        if isinstance(searchpath, string_types):
+            searchpath = [searchpath]
+        self.searchpath = list(searchpath)
+        self.encoding = encoding
+        self.followlinks = followlinks
+
+    def get_source(self, environment, template):
+        pieces = split_template_path(template)
+        for searchpath in self.searchpath:
+            filename = path.join(searchpath, *pieces)
+            f = open_if_exists(filename)
+            if f is None:
+                continue
+            try:
+                contents = f.read().decode(self.encoding)
+            finally:
+                f.close()
+
+            mtime = path.getmtime(filename)
+
+            def uptodate():
+                try:
+                    return path.getmtime(filename) == mtime
+                except OSError:
+                    return False
+            return contents, filename, uptodate
+        raise TemplateNotFound(template)
+
+    def list_templates(self):
+        found = set()
+        for searchpath in self.searchpath:
+            walk_dir = os.walk(searchpath, followlinks=self.followlinks)
+            for dirpath, dirnames, filenames in walk_dir:
+                for filename in filenames:
+                    template = os.path.join(dirpath, filename) \
+                        [len(searchpath):].strip(os.path.sep) \
+                                          .replace(os.path.sep, '/')
+                    if template[:2] == './':
+                        template = template[2:]
+                    if template not in found:
+                        found.add(template)
+        return sorted(found)
+
+
+class PackageLoader(BaseLoader):
+    """Load templates from python eggs or packages.  It is constructed with
+    the name of the python package and the path to the templates in that
+    package::
+
+        loader = PackageLoader('mypackage', 'views')
+
+    If the package path is not given, ``'templates'`` is assumed.
+
+    Per default the template encoding is ``'utf-8'`` which can be changed
+    by setting the `encoding` parameter to something else.  Due to the nature
+    of eggs it's only possible to reload templates if the package was loaded
+    from the file system and not a zip file.
+    """
+
+    def __init__(self, package_name, package_path='templates',
+                 encoding='utf-8'):
+        from pkg_resources import DefaultProvider, ResourceManager, \
+                                  get_provider
+        provider = get_provider(package_name)
+        self.encoding = encoding
+        self.manager = ResourceManager()
+        self.filesystem_bound = isinstance(provider, DefaultProvider)
+        self.provider = provider
+        self.package_path = package_path
+
+    def get_source(self, environment, template):
+        pieces = split_template_path(template)
+        p = '/'.join((self.package_path,) + tuple(pieces))
+        if not self.provider.has_resource(p):
+            raise TemplateNotFound(template)
+
+        filename = uptodate = None
+        if self.filesystem_bound:
+            filename = self.provider.get_resource_filename(self.manager, p)
+            mtime = path.getmtime(filename)
+            def uptodate():
+                try:
+                    return path.getmtime(filename) == mtime
+                except OSError:
+                    return False
+
+        source = self.provider.get_resource_string(self.manager, p)
+        return source.decode(self.encoding), filename, uptodate
+
+    def list_templates(self):
+        path = self.package_path
+        if path[:2] == './':
+            path = path[2:]
+        elif path == '.':
+            path = ''
+        offset = len(path)
+        results = []
+        def _walk(path):
+            for filename in self.provider.resource_listdir(path):
+                fullname = path + '/' + filename
+                if self.provider.resource_isdir(fullname):
+                    _walk(fullname)
+                else:
+                    results.append(fullname[offset:].lstrip('/'))
+        _walk(path)
+        results.sort()
+        return results
+
+
+class DictLoader(BaseLoader):
+    """Loads a template from a python dict.  It's passed a dict of unicode
+    strings bound to template names.  This loader is useful for unittesting:
+
+    >>> loader = DictLoader({'index.html': 'source here'})
+
+    Because auto reloading is rarely useful this is disabled per default.
+    """
+
+    def __init__(self, mapping):
+        self.mapping = mapping
+
+    def get_source(self, environment, template):
+        if template in self.mapping:
+            source = self.mapping[template]
+            return source, None, lambda: source == self.mapping.get(template)
+        raise TemplateNotFound(template)
+
+    def list_templates(self):
+        return sorted(self.mapping)
+
+
+class FunctionLoader(BaseLoader):
+    """A loader that is passed a function which does the loading.  The
+    function receives the name of the template and has to return either
+    an unicode string with the template source, a tuple in the form ``(source,
+    filename, uptodatefunc)`` or `None` if the template does not exist.
+
+    >>> def load_template(name):
+    ...     if name == 'index.html':
+    ...         return '...'
+    ...
+    >>> loader = FunctionLoader(load_template)
+
+    The `uptodatefunc` is a function that is called if autoreload is enabled
+    and has to return `True` if the template is still up to date.  For more
+    details have a look at :meth:`BaseLoader.get_source` which has the same
+    return value.
+    """
+
+    def __init__(self, load_func):
+        self.load_func = load_func
+
+    def get_source(self, environment, template):
+        rv = self.load_func(template)
+        if rv is None:
+            raise TemplateNotFound(template)
+        elif isinstance(rv, string_types):
+            return rv, None, None
+        return rv
+
+
+class PrefixLoader(BaseLoader):
+    """A loader that is passed a dict of loaders where each loader is bound
+    to a prefix.  The prefix is delimited from the template by a slash per
+    default, which can be changed by setting the `delimiter` argument to
+    something else::
+
+        loader = PrefixLoader({
+            'app1':     PackageLoader('mypackage.app1'),
+            'app2':     PackageLoader('mypackage.app2')
+        })
+
+    By loading ``'app1/index.html'`` the file from the app1 package is loaded,
+    by loading ``'app2/index.html'`` the file from the second.
+    """
+
+    def __init__(self, mapping, delimiter='/'):
+        self.mapping = mapping
+        self.delimiter = delimiter
+
+    def get_loader(self, template):
+        try:
+            prefix, name = template.split(self.delimiter, 1)
+            loader = self.mapping[prefix]
+        except (ValueError, KeyError):
+            raise TemplateNotFound(template)
+        return loader, name
+
+    def get_source(self, environment, template):
+        loader, name = self.get_loader(template)
+        try:
+            return loader.get_source(environment, name)
+        except TemplateNotFound:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(template)
+
+    @internalcode
+    def load(self, environment, name, globals=None):
+        loader, local_name = self.get_loader(name)
+        try:
+            return loader.load(environment, local_name, globals)
+        except TemplateNotFound:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(name)
+
+    def list_templates(self):
+        result = []
+        for prefix, loader in iteritems(self.mapping):
+            for template in loader.list_templates():
+                result.append(prefix + self.delimiter + template)
+        return result
+
+
+class ChoiceLoader(BaseLoader):
+    """This loader works like the `PrefixLoader` just that no prefix is
+    specified.  If a template could not be found by one loader the next one
+    is tried.
+
+    >>> loader = ChoiceLoader([
+    ...     FileSystemLoader('/path/to/user/templates'),
+    ...     FileSystemLoader('/path/to/system/templates')
+    ... ])
+
+    This is useful if you want to allow users to override builtin templates
+    from a different location.
+    """
+
+    def __init__(self, loaders):
+        self.loaders = loaders
+
+    def get_source(self, environment, template):
+        for loader in self.loaders:
+            try:
+                return loader.get_source(environment, template)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(template)
+
+    @internalcode
+    def load(self, environment, name, globals=None):
+        for loader in self.loaders:
+            try:
+                return loader.load(environment, name, globals)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(name)
+
+    def list_templates(self):
+        found = set()
+        for loader in self.loaders:
+            found.update(loader.list_templates())
+        return sorted(found)
+
+
+class _TemplateModule(ModuleType):
+    """Like a normal module but with support for weak references"""
+
+
+class ModuleLoader(BaseLoader):
+    """This loader loads templates from precompiled templates.
+
+    Example usage:
+
+    >>> loader = ChoiceLoader([
+    ...     ModuleLoader('/path/to/compiled/templates'),
+    ...     FileSystemLoader('/path/to/templates')
+    ... ])
+
+    Templates can be precompiled with :meth:`Environment.compile_templates`.
+    """
+
+    has_source_access = False
+
+    def __init__(self, path):
+        package_name = '_jinja2_module_templates_%x' % id(self)
+
+        # create a fake module that looks for the templates in the
+        # path given.
+        mod = _TemplateModule(package_name)
+        if isinstance(path, string_types):
+            path = [path]
+        else:
+            path = list(path)
+        mod.__path__ = path
+
+        sys.modules[package_name] = weakref.proxy(mod,
+            lambda x: sys.modules.pop(package_name, None))
+
+        # the only strong reference, the sys.modules entry is weak
+        # so that the garbage collector can remove it once the
+        # loader that created it goes out of business.
+        self.module = mod
+        self.package_name = package_name
+
+    @staticmethod
+    def get_template_key(name):
+        return 'tmpl_' + sha1(name.encode('utf-8')).hexdigest()
+
+    @staticmethod
+    def get_module_filename(name):
+        return ModuleLoader.get_template_key(name) + '.py'
+
+    @internalcode
+    def load(self, environment, name, globals=None):
+        key = self.get_template_key(name)
+        module = '%s.%s' % (self.package_name, key)
+        mod = getattr(self.module, module, None)
+        if mod is None:
+            try:
+                mod = __import__(module, None, None, ['root'])
+            except ImportError:
+                raise TemplateNotFound(name)
+
+            # remove the entry from sys.modules, we only want the attribute
+            # on the module object we have stored on the loader.
+            sys.modules.pop(module, None)
+
+        return environment.template_class.from_module_dict(
+            environment, mod.__dict__, globals)
diff --git a/python/jinja2/meta.py b/python/jinja2/meta.py
new file mode 100644
index 0000000..7421914
--- /dev/null
+++ b/python/jinja2/meta.py
@@ -0,0 +1,106 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.meta
+    ~~~~~~~~~~~
+
+    This module implements various functions that exposes information about
+    templates that might be interesting for various kinds of applications.
+
+    :copyright: (c) 2017 by the Jinja Team, see AUTHORS for more details.
+    :license: BSD, see LICENSE for more details.
+"""
+from jinja2 import nodes
+from jinja2.compiler import CodeGenerator
+from jinja2._compat import string_types, iteritems
+
+
+class TrackingCodeGenerator(CodeGenerator):
+    """We abuse the code generator for introspection."""
+
+    def __init__(self, environment):
+        CodeGenerator.__init__(self, environment, '<introspection>',
+                               '<introspection>')
+        self.undeclared_identifiers = set()
+
+    def write(self, x):
+        """Don't write."""
+
+    def enter_frame(self, frame):
+        """Remember all undeclared identifiers."""
+        CodeGenerator.enter_frame(self, frame)
+        for _, (action, param) in iteritems(frame.symbols.loads):
+            if action == 'resolve':
+                self.undeclared_identifiers.add(param)
+
+
+def find_undeclared_variables(ast):
+    """Returns a set of all variables in the AST that will be looked up from
+    the context at runtime.  Because at compile time it's not known which
+    variables will be used depending on the path the execution takes at
+    runtime, all variables are returned.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
+    >>> meta.find_undeclared_variables(ast) == set(['bar'])
+    True
+
+    .. admonition:: Implementation
+
+       Internally the code generator is used for finding undeclared variables.
+       This is good to know because the code generator might raise a
+       :exc:`TemplateAssertionError` during compilation and as a matter of
+       fact this function can currently raise that exception as well.
+    """
+    codegen = TrackingCodeGenerator(ast.environment)
+    codegen.visit(ast)
+    return codegen.undeclared_identifiers
+
+
+def find_referenced_templates(ast):
+    """Finds all the referenced templates from the AST.  This will return an
+    iterator over all the hardcoded template extensions, inclusions and
+    imports.  If dynamic inheritance or inclusion is used, `None` will be
+    yielded.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% extends "layout.html" %}{% include helper %}')
+    >>> list(meta.find_referenced_templates(ast))
+    ['layout.html', None]
+
+    This function is useful for dependency tracking.  For example if you want
+    to rebuild parts of the website after a layout template has changed.
+    """
+    for node in ast.find_all((nodes.Extends, nodes.FromImport, nodes.Import,
+                              nodes.Include)):
+        if not isinstance(node.template, nodes.Const):
+            # a tuple with some non consts in there
+            if isinstance(node.template, (nodes.Tuple, nodes.List)):
+                for template_name in node.template.items:
+                    # something const, only yield the strings and ignore
+                    # non-string consts that really just make no sense
+                    if isinstance(template_name, nodes.Const):
+                        if isinstance(template_name.value, string_types):
+                            yield template_name.value
+                    # something dynamic in there
+                    else:
+                        yield None
+            # something dynamic we don't know about here
+            else:
+                yield None
+            continue
+        # constant is a basestring, direct template name
+        if isinstance(node.template.value, string_types):
+            yield node.template.value
+        # a tuple or list (latter *should* not happen) made of consts,
+        # yield the consts that are strings.  We could warn here for
+        # non string values
+        elif isinstance(node, nodes.Include) and \
+             isinstance(node.template.value, (tuple, list)):
+            for template_name in node.template.value:
+                if isinstance(template_name, string_types):
+                    yield template_name
+        # something else we don't care about, we could warn here
+        else:
+            yield None
diff --git a/python/jinja2/nativetypes.py b/python/jinja2/nativetypes.py
new file mode 100644
index 0000000..fe17e41
--- /dev/null
+++ b/python/jinja2/nativetypes.py
@@ -0,0 +1,220 @@
+import sys
+from ast import literal_eval
+from itertools import islice, chain
+from jinja2 import nodes
+from jinja2._compat import text_type
+from jinja2.compiler import CodeGenerator, has_safe_repr
+from jinja2.environment import Environment, Template
+from jinja2.utils import concat, escape
+
+
+def native_concat(nodes):
+    """Return a native Python type from the list of compiled nodes. If the
+    result is a single node, its value is returned. Otherwise, the nodes are
+    concatenated as strings. If the result can be parsed with
+    :func:`ast.literal_eval`, the parsed value is returned. Otherwise, the
+    string is returned.
+    """
+    head = list(islice(nodes, 2))
+
+    if not head:
+        return None
+
+    if len(head) == 1:
+        out = head[0]
+    else:
+        out = u''.join([text_type(v) for v in chain(head, nodes)])
+
+    try:
+        return literal_eval(out)
+    except (ValueError, SyntaxError, MemoryError):
+        return out
+
+
+class NativeCodeGenerator(CodeGenerator):
+    """A code generator which avoids injecting ``to_string()`` calls around the
+    internal code Jinja uses to render templates.
+    """
+
+    def visit_Output(self, node, frame):
+        """Same as :meth:`CodeGenerator.visit_Output`, but do not call
+        ``to_string`` on output nodes in generated code.
+        """
+        if self.has_known_extends and frame.require_output_check:
+            return
+
+        finalize = self.environment.finalize
+        finalize_context = getattr(finalize, 'contextfunction', False)
+        finalize_eval = getattr(finalize, 'evalcontextfunction', False)
+        finalize_env = getattr(finalize, 'environmentfunction', False)
+
+        if finalize is not None:
+            if finalize_context or finalize_eval:
+                const_finalize = None
+            elif finalize_env:
+                def const_finalize(x):
+                    return finalize(self.environment, x)
+            else:
+                const_finalize = finalize
+        else:
+            def const_finalize(x):
+                return x
+
+        # If we are inside a frame that requires output checking, we do so.
+        outdent_later = False
+
+        if frame.require_output_check:
+            self.writeline('if parent_template is None:')
+            self.indent()
+            outdent_later = True
+
+        # Try to evaluate as many chunks as possible into a static string at
+        # compile time.
+        body = []
+
+        for child in node.nodes:
+            try:
+                if const_finalize is None:
+                    raise nodes.Impossible()
+
+                const = child.as_const(frame.eval_ctx)
+                if not has_safe_repr(const):
+                    raise nodes.Impossible()
+            except nodes.Impossible:
+                body.append(child)
+                continue
+
+            # the frame can't be volatile here, because otherwise the as_const
+            # function would raise an Impossible exception at that point
+            try:
+                if frame.eval_ctx.autoescape:
+                    if hasattr(const, '__html__'):
+                        const = const.__html__()
+                    else:
+                        const = escape(const)
+
+                const = const_finalize(const)
+            except Exception:
+                # if something goes wrong here we evaluate the node at runtime
+                # for easier debugging
+                body.append(child)
+                continue
+
+            if body and isinstance(body[-1], list):
+                body[-1].append(const)
+            else:
+                body.append([const])
+
+        # if we have less than 3 nodes or a buffer we yield or extend/append
+        if len(body) < 3 or frame.buffer is not None:
+            if frame.buffer is not None:
+                # for one item we append, for more we extend
+                if len(body) == 1:
+                    self.writeline('%s.append(' % frame.buffer)
+                else:
+                    self.writeline('%s.extend((' % frame.buffer)
+
+                self.indent()
+
+            for item in body:
+                if isinstance(item, list):
+                    val = repr(native_concat(item))
+
+                    if frame.buffer is None:
+                        self.writeline('yield ' + val)
+                    else:
+                        self.writeline(val + ',')
+                else:
+                    if frame.buffer is None:
+                        self.writeline('yield ', item)
+                    else:
+                        self.newline(item)
+
+                    close = 0
+
+                    if finalize is not None:
+                        self.write('environment.finalize(')
+
+                        if finalize_context:
+                            self.write('context, ')
+
+                        close += 1
+
+                    self.visit(item, frame)
+
+                    if close > 0:
+                        self.write(')' * close)
+
+                    if frame.buffer is not None:
+                        self.write(',')
+
+            if frame.buffer is not None:
+                # close the open parentheses
+                self.outdent()
+                self.writeline(len(body) == 1 and ')' or '))')
+
+        # otherwise we create a format string as this is faster in that case
+        else:
+            format = []
+            arguments = []
+
+            for item in body:
+                if isinstance(item, list):
+                    format.append(native_concat(item).replace('%', '%%'))
+                else:
+                    format.append('%s')
+                    arguments.append(item)
+
+            self.writeline('yield ')
+            self.write(repr(concat(format)) + ' % (')
+            self.indent()
+
+            for argument in arguments:
+                self.newline(argument)
+                close = 0
+
+                if finalize is not None:
+                    self.write('environment.finalize(')
+
+                    if finalize_context:
+                        self.write('context, ')
+                    elif finalize_eval:
+                        self.write('context.eval_ctx, ')
+                    elif finalize_env:
+                        self.write('environment, ')
+
+                    close += 1
+
+                self.visit(argument, frame)
+                self.write(')' * close + ', ')
+
+            self.outdent()
+            self.writeline(')')
+
+        if outdent_later:
+            self.outdent()
+
+
+class NativeTemplate(Template):
+    def render(self, *args, **kwargs):
+        """Render the template to produce a native Python type. If the result
+        is a single node, its value is returned. Otherwise, the nodes are
+        concatenated as strings. If the result can be parsed with
+        :func:`ast.literal_eval`, the parsed value is returned. Otherwise, the
+        string is returned.
+        """
+        vars = dict(*args, **kwargs)
+
+        try:
+            return native_concat(self.root_render_func(self.new_context(vars)))
+        except Exception:
+            exc_info = sys.exc_info()
+
+        return self.environment.handle_exception(exc_info, True)
+
+
+class NativeEnvironment(Environment):
+    """An environment that renders templates to native Python types."""
+
+    code_generator_class = NativeCodeGenerator
+    template_class = NativeTemplate
diff --git a/python/jinja2/nodes.py b/python/jinja2/nodes.py
new file mode 100644
index 0000000..4d9a01a
--- /dev/null
+++ b/python/jinja2/nodes.py
@@ -0,0 +1,999 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.nodes
+    ~~~~~~~~~~~~
+
+    This module implements additional nodes derived from the ast base node.
+
+    It also provides some node tree helper functions like `in_lineno` and
+    `get_nodes` used by the parser and translator in order to normalize
+    python and jinja nodes.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import types
+import operator
+
+from collections import deque
+from jinja2.utils import Markup
+from jinja2._compat import izip, with_metaclass, text_type, PY2
+
+
+#: the types we support for context functions
+_context_function_types = (types.FunctionType, types.MethodType)
+
+
+_binop_to_func = {
+    '*':        operator.mul,
+    '/':        operator.truediv,
+    '//':       operator.floordiv,
+    '**':       operator.pow,
+    '%':        operator.mod,
+    '+':        operator.add,
+    '-':        operator.sub
+}
+
+_uaop_to_func = {
+    'not':      operator.not_,
+    '+':        operator.pos,
+    '-':        operator.neg
+}
+
+_cmpop_to_func = {
+    'eq':       operator.eq,
+    'ne':       operator.ne,
+    'gt':       operator.gt,
+    'gteq':     operator.ge,
+    'lt':       operator.lt,
+    'lteq':     operator.le,
+    'in':       lambda a, b: a in b,
+    'notin':    lambda a, b: a not in b
+}
+
+
+class Impossible(Exception):
+    """Raised if the node could not perform a requested action."""
+
+
+class NodeType(type):
+    """A metaclass for nodes that handles the field and attribute
+    inheritance.  fields and attributes from the parent class are
+    automatically forwarded to the child."""
+
+    def __new__(cls, name, bases, d):
+        for attr in 'fields', 'attributes':
+            storage = []
+            storage.extend(getattr(bases[0], attr, ()))
+            storage.extend(d.get(attr, ()))
+            assert len(bases) == 1, 'multiple inheritance not allowed'
+            assert len(storage) == len(set(storage)), 'layout conflict'
+            d[attr] = tuple(storage)
+        d.setdefault('abstract', False)
+        return type.__new__(cls, name, bases, d)
+
+
+class EvalContext(object):
+    """Holds evaluation time information.  Custom attributes can be attached
+    to it in extensions.
+    """
+
+    def __init__(self, environment, template_name=None):
+        self.environment = environment
+        if callable(environment.autoescape):
+            self.autoescape = environment.autoescape(template_name)
+        else:
+            self.autoescape = environment.autoescape
+        self.volatile = False
+
+    def save(self):
+        return self.__dict__.copy()
+
+    def revert(self, old):
+        self.__dict__.clear()
+        self.__dict__.update(old)
+
+
+def get_eval_context(node, ctx):
+    if ctx is None:
+        if node.environment is None:
+            raise RuntimeError('if no eval context is passed, the '
+                               'node must have an attached '
+                               'environment.')
+        return EvalContext(node.environment)
+    return ctx
+
+
+class Node(with_metaclass(NodeType, object)):
+    """Baseclass for all Jinja2 nodes.  There are a number of nodes available
+    of different types.  There are four major types:
+
+    -   :class:`Stmt`: statements
+    -   :class:`Expr`: expressions
+    -   :class:`Helper`: helper nodes
+    -   :class:`Template`: the outermost wrapper node
+
+    All nodes have fields and attributes.  Fields may be other nodes, lists,
+    or arbitrary values.  Fields are passed to the constructor as regular
+    positional arguments, attributes as keyword arguments.  Each node has
+    two attributes: `lineno` (the line number of the node) and `environment`.
+    The `environment` attribute is set at the end of the parsing process for
+    all nodes automatically.
+    """
+    fields = ()
+    attributes = ('lineno', 'environment')
+    abstract = True
+
+    def __init__(self, *fields, **attributes):
+        if self.abstract:
+            raise TypeError('abstract nodes are not instanciable')
+        if fields:
+            if len(fields) != len(self.fields):
+                if not self.fields:
+                    raise TypeError('%r takes 0 arguments' %
+                                    self.__class__.__name__)
+                raise TypeError('%r takes 0 or %d argument%s' % (
+                    self.__class__.__name__,
+                    len(self.fields),
+                    len(self.fields) != 1 and 's' or ''
+                ))
+            for name, arg in izip(self.fields, fields):
+                setattr(self, name, arg)
+        for attr in self.attributes:
+            setattr(self, attr, attributes.pop(attr, None))
+        if attributes:
+            raise TypeError('unknown attribute %r' %
+                            next(iter(attributes)))
+
+    def iter_fields(self, exclude=None, only=None):
+        """This method iterates over all fields that are defined and yields
+        ``(key, value)`` tuples.  Per default all fields are returned, but
+        it's possible to limit that to some fields by providing the `only`
+        parameter or to exclude some using the `exclude` parameter.  Both
+        should be sets or tuples of field names.
+        """
+        for name in self.fields:
+            if (exclude is only is None) or \
+               (exclude is not None and name not in exclude) or \
+               (only is not None and name in only):
+                try:
+                    yield name, getattr(self, name)
+                except AttributeError:
+                    pass
+
+    def iter_child_nodes(self, exclude=None, only=None):
+        """Iterates over all direct child nodes of the node.  This iterates
+        over all fields and yields the values of they are nodes.  If the value
+        of a field is a list all the nodes in that list are returned.
+        """
+        for field, item in self.iter_fields(exclude, only):
+            if isinstance(item, list):
+                for n in item:
+                    if isinstance(n, Node):
+                        yield n
+            elif isinstance(item, Node):
+                yield item
+
+    def find(self, node_type):
+        """Find the first node of a given type.  If no such node exists the
+        return value is `None`.
+        """
+        for result in self.find_all(node_type):
+            return result
+
+    def find_all(self, node_type):
+        """Find all the nodes of a given type.  If the type is a tuple,
+        the check is performed for any of the tuple items.
+        """
+        for child in self.iter_child_nodes():
+            if isinstance(child, node_type):
+                yield child
+            for result in child.find_all(node_type):
+                yield result
+
+    def set_ctx(self, ctx):
+        """Reset the context of a node and all child nodes.  Per default the
+        parser will all generate nodes that have a 'load' context as it's the
+        most common one.  This method is used in the parser to set assignment
+        targets and other nodes to a store context.
+        """
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if 'ctx' in node.fields:
+                node.ctx = ctx
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_lineno(self, lineno, override=False):
+        """Set the line numbers of the node and children."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if 'lineno' in node.attributes:
+                if node.lineno is None or override:
+                    node.lineno = lineno
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_environment(self, environment):
+        """Set the environment for all nodes."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            node.environment = environment
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def __eq__(self, other):
+        return type(self) is type(other) and \
+               tuple(self.iter_fields()) == tuple(other.iter_fields())
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    # Restore Python 2 hashing behavior on Python 3
+    __hash__ = object.__hash__
+
+    def __repr__(self):
+        return '%s(%s)' % (
+            self.__class__.__name__,
+            ', '.join('%s=%r' % (arg, getattr(self, arg, None)) for
+                      arg in self.fields)
+        )
+
+    def dump(self):
+        def _dump(node):
+            if not isinstance(node, Node):
+                buf.append(repr(node))
+                return
+
+            buf.append('nodes.%s(' % node.__class__.__name__)
+            if not node.fields:
+                buf.append(')')
+                return
+            for idx, field in enumerate(node.fields):
+                if idx:
+                    buf.append(', ')
+                value = getattr(node, field)
+                if isinstance(value, list):
+                    buf.append('[')
+                    for idx, item in enumerate(value):
+                        if idx:
+                            buf.append(', ')
+                        _dump(item)
+                    buf.append(']')
+                else:
+                    _dump(value)
+            buf.append(')')
+        buf = []
+        _dump(self)
+        return ''.join(buf)
+
+
+
+class Stmt(Node):
+    """Base node for all statements."""
+    abstract = True
+
+
+class Helper(Node):
+    """Nodes that exist in a specific context only."""
+    abstract = True
+
+
+class Template(Node):
+    """Node that represents a template.  This must be the outermost node that
+    is passed to the compiler.
+    """
+    fields = ('body',)
+
+
+class Output(Stmt):
+    """A node that holds multiple expressions which are then printed out.
+    This is used both for the `print` statement and the regular template data.
+    """
+    fields = ('nodes',)
+
+
+class Extends(Stmt):
+    """Represents an extends statement."""
+    fields = ('template',)
+
+
+class For(Stmt):
+    """The for loop.  `target` is the target for the iteration (usually a
+    :class:`Name` or :class:`Tuple`), `iter` the iterable.  `body` is a list
+    of nodes that are used as loop-body, and `else_` a list of nodes for the
+    `else` block.  If no else node exists it has to be an empty list.
+
+    For filtered nodes an expression can be stored as `test`, otherwise `None`.
+    """
+    fields = ('target', 'iter', 'body', 'else_', 'test', 'recursive')
+
+
+class If(Stmt):
+    """If `test` is true, `body` is rendered, else `else_`."""
+    fields = ('test', 'body', 'elif_', 'else_')
+
+
+class Macro(Stmt):
+    """A macro definition.  `name` is the name of the macro, `args` a list of
+    arguments and `defaults` a list of defaults if there are any.  `body` is
+    a list of nodes for the macro body.
+    """
+    fields = ('name', 'args', 'defaults', 'body')
+
+
+class CallBlock(Stmt):
+    """Like a macro without a name but a call instead.  `call` is called with
+    the unnamed macro as `caller` argument this node holds.
+    """
+    fields = ('call', 'args', 'defaults', 'body')
+
+
+class FilterBlock(Stmt):
+    """Node for filter sections."""
+    fields = ('body', 'filter')
+
+
+class With(Stmt):
+    """Specific node for with statements.  In older versions of Jinja the
+    with statement was implemented on the base of the `Scope` node instead.
+
+    .. versionadded:: 2.9.3
+    """
+    fields = ('targets', 'values', 'body')
+
+
+class Block(Stmt):
+    """A node that represents a block."""
+    fields = ('name', 'body', 'scoped')
+
+
+class Include(Stmt):
+    """A node that represents the include tag."""
+    fields = ('template', 'with_context', 'ignore_missing')
+
+
+class Import(Stmt):
+    """A node that represents the import tag."""
+    fields = ('template', 'target', 'with_context')
+
+
+class FromImport(Stmt):
+    """A node that represents the from import tag.  It's important to not
+    pass unsafe names to the name attribute.  The compiler translates the
+    attribute lookups directly into getattr calls and does *not* use the
+    subscript callback of the interface.  As exported variables may not
+    start with double underscores (which the parser asserts) this is not a
+    problem for regular Jinja code, but if this node is used in an extension
+    extra care must be taken.
+
+    The list of names may contain tuples if aliases are wanted.
+    """
+    fields = ('template', 'names', 'with_context')
+
+
+class ExprStmt(Stmt):
+    """A statement that evaluates an expression and discards the result."""
+    fields = ('node',)
+
+
+class Assign(Stmt):
+    """Assigns an expression to a target."""
+    fields = ('target', 'node')
+
+
+class AssignBlock(Stmt):
+    """Assigns a block to a target."""
+    fields = ('target', 'filter', 'body')
+
+
+class Expr(Node):
+    """Baseclass for all expressions."""
+    abstract = True
+
+    def as_const(self, eval_ctx=None):
+        """Return the value of the expression as constant or raise
+        :exc:`Impossible` if this was not possible.
+
+        An :class:`EvalContext` can be provided, if none is given
+        a default context is created which requires the nodes to have
+        an attached environment.
+
+        .. versionchanged:: 2.4
+           the `eval_ctx` parameter was added.
+        """
+        raise Impossible()
+
+    def can_assign(self):
+        """Check if it's possible to assign something to this node."""
+        return False
+
+
+class BinExpr(Expr):
+    """Baseclass for all binary expressions."""
+    fields = ('left', 'right')
+    operator = None
+    abstract = True
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        # intercepted operators cannot be folded at compile time
+        if self.environment.sandboxed and \
+           self.operator in self.environment.intercepted_binops:
+            raise Impossible()
+        f = _binop_to_func[self.operator]
+        try:
+            return f(self.left.as_const(eval_ctx), self.right.as_const(eval_ctx))
+        except Exception:
+            raise Impossible()
+
+
+class UnaryExpr(Expr):
+    """Baseclass for all unary expressions."""
+    fields = ('node',)
+    operator = None
+    abstract = True
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        # intercepted operators cannot be folded at compile time
+        if self.environment.sandboxed and \
+           self.operator in self.environment.intercepted_unops:
+            raise Impossible()
+        f = _uaop_to_func[self.operator]
+        try:
+            return f(self.node.as_const(eval_ctx))
+        except Exception:
+            raise Impossible()
+
+
+class Name(Expr):
+    """Looks up a name or stores a value in a name.
+    The `ctx` of the node can be one of the following values:
+
+    -   `store`: store a value in the name
+    -   `load`: load that name
+    -   `param`: like `store` but if the name was defined as function parameter.
+    """
+    fields = ('name', 'ctx')
+
+    def can_assign(self):
+        return self.name not in ('true', 'false', 'none',
+                                 'True', 'False', 'None')
+
+
+class NSRef(Expr):
+    """Reference to a namespace value assignment"""
+    fields = ('name', 'attr')
+
+    def can_assign(self):
+        # We don't need any special checks here; NSRef assignments have a
+        # runtime check to ensure the target is a namespace object which will
+        # have been checked already as it is created using a normal assignment
+        # which goes through a `Name` node.
+        return True
+
+
+class Literal(Expr):
+    """Baseclass for literals."""
+    abstract = True
+
+
+class Const(Literal):
+    """All constant values.  The parser will return this node for simple
+    constants such as ``42`` or ``"foo"`` but it can be used to store more
+    complex values such as lists too.  Only constants with a safe
+    representation (objects where ``eval(repr(x)) == x`` is true).
+    """
+    fields = ('value',)
+
+    def as_const(self, eval_ctx=None):
+        rv = self.value
+        if PY2 and type(rv) is text_type and \
+           self.environment.policies['compiler.ascii_str']:
+            try:
+                rv = rv.encode('ascii')
+            except UnicodeError:
+                pass
+        return rv
+
+    @classmethod
+    def from_untrusted(cls, value, lineno=None, environment=None):
+        """Return a const object if the value is representable as
+        constant value in the generated code, otherwise it will raise
+        an `Impossible` exception.
+        """
+        from .compiler import has_safe_repr
+        if not has_safe_repr(value):
+            raise Impossible()
+        return cls(value, lineno=lineno, environment=environment)
+
+
+class TemplateData(Literal):
+    """A constant template string."""
+    fields = ('data',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        if eval_ctx.autoescape:
+            return Markup(self.data)
+        return self.data
+
+
+class Tuple(Literal):
+    """For loop unpacking and some other things like multiple arguments
+    for subscripts.  Like for :class:`Name` `ctx` specifies if the tuple
+    is used for loading the names or storing.
+    """
+    fields = ('items', 'ctx')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return tuple(x.as_const(eval_ctx) for x in self.items)
+
+    def can_assign(self):
+        for item in self.items:
+            if not item.can_assign():
+                return False
+        return True
+
+
+class List(Literal):
+    """Any list literal such as ``[1, 2, 3]``"""
+    fields = ('items',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return [x.as_const(eval_ctx) for x in self.items]
+
+
+class Dict(Literal):
+    """Any dict literal such as ``{1: 2, 3: 4}``.  The items must be a list of
+    :class:`Pair` nodes.
+    """
+    fields = ('items',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return dict(x.as_const(eval_ctx) for x in self.items)
+
+
+class Pair(Helper):
+    """A key, value pair for dicts."""
+    fields = ('key', 'value')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key.as_const(eval_ctx), self.value.as_const(eval_ctx)
+
+
+class Keyword(Helper):
+    """A key, value pair for keyword arguments where key is a string."""
+    fields = ('key', 'value')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key, self.value.as_const(eval_ctx)
+
+
+class CondExpr(Expr):
+    """A conditional expression (inline if expression).  (``{{
+    foo if bar else baz }}``)
+    """
+    fields = ('test', 'expr1', 'expr2')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if self.test.as_const(eval_ctx):
+            return self.expr1.as_const(eval_ctx)
+
+        # if we evaluate to an undefined object, we better do that at runtime
+        if self.expr2 is None:
+            raise Impossible()
+
+        return self.expr2.as_const(eval_ctx)
+
+
+def args_as_const(node, eval_ctx):
+    args = [x.as_const(eval_ctx) for x in node.args]
+    kwargs = dict(x.as_const(eval_ctx) for x in node.kwargs)
+
+    if node.dyn_args is not None:
+        try:
+            args.extend(node.dyn_args.as_const(eval_ctx))
+        except Exception:
+            raise Impossible()
+
+    if node.dyn_kwargs is not None:
+        try:
+            kwargs.update(node.dyn_kwargs.as_const(eval_ctx))
+        except Exception:
+            raise Impossible()
+
+    return args, kwargs
+
+
+class Filter(Expr):
+    """This node applies a filter on an expression.  `name` is the name of
+    the filter, the rest of the fields are the same as for :class:`Call`.
+
+    If the `node` of a filter is `None` the contents of the last buffer are
+    filtered.  Buffers are created by macros and filter blocks.
+    """
+
+    fields = ('node', 'name', 'args', 'kwargs', 'dyn_args', 'dyn_kwargs')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        if eval_ctx.volatile or self.node is None:
+            raise Impossible()
+
+        # we have to be careful here because we call filter_ below.
+        # if this variable would be called filter, 2to3 would wrap the
+        # call in a list beause it is assuming we are talking about the
+        # builtin filter function here which no longer returns a list in
+        # python 3.  because of that, do not rename filter_ to filter!
+        filter_ = self.environment.filters.get(self.name)
+
+        if filter_ is None or getattr(filter_, 'contextfilter', False):
+            raise Impossible()
+
+        # We cannot constant handle async filters, so we need to make sure
+        # to not go down this path.
+        if (
+            eval_ctx.environment.is_async
+            and getattr(filter_, 'asyncfiltervariant', False)
+        ):
+            raise Impossible()
+
+        args, kwargs = args_as_const(self, eval_ctx)
+        args.insert(0, self.node.as_const(eval_ctx))
+
+        if getattr(filter_, 'evalcontextfilter', False):
+            args.insert(0, eval_ctx)
+        elif getattr(filter_, 'environmentfilter', False):
+            args.insert(0, self.environment)
+
+        try:
+            return filter_(*args, **kwargs)
+        except Exception:
+            raise Impossible()
+
+
+class Test(Expr):
+    """Applies a test on an expression.  `name` is the name of the test, the
+    rest of the fields are the same as for :class:`Call`.
+    """
+
+    fields = ('node', 'name', 'args', 'kwargs', 'dyn_args', 'dyn_kwargs')
+
+    def as_const(self, eval_ctx=None):
+        test = self.environment.tests.get(self.name)
+
+        if test is None:
+            raise Impossible()
+
+        eval_ctx = get_eval_context(self, eval_ctx)
+        args, kwargs = args_as_const(self, eval_ctx)
+        args.insert(0, self.node.as_const(eval_ctx))
+
+        try:
+            return test(*args, **kwargs)
+        except Exception:
+            raise Impossible()
+
+
+class Call(Expr):
+    """Calls an expression.  `args` is a list of arguments, `kwargs` a list
+    of keyword arguments (list of :class:`Keyword` nodes), and `dyn_args`
+    and `dyn_kwargs` has to be either `None` or a node that is used as
+    node for dynamic positional (``*args``) or keyword (``**kwargs``)
+    arguments.
+    """
+    fields = ('node', 'args', 'kwargs', 'dyn_args', 'dyn_kwargs')
+
+
+class Getitem(Expr):
+    """Get an attribute or item from an expression and prefer the item."""
+    fields = ('node', 'arg', 'ctx')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if self.ctx != 'load':
+            raise Impossible()
+        try:
+            return self.environment.getitem(self.node.as_const(eval_ctx),
+                                            self.arg.as_const(eval_ctx))
+        except Exception:
+            raise Impossible()
+
+    def can_assign(self):
+        return False
+
+
+class Getattr(Expr):
+    """Get an attribute or item from an expression that is a ascii-only
+    bytestring and prefer the attribute.
+    """
+    fields = ('node', 'attr', 'ctx')
+
+    def as_const(self, eval_ctx=None):
+        if self.ctx != 'load':
+            raise Impossible()
+        try:
+            eval_ctx = get_eval_context(self, eval_ctx)
+            return self.environment.getattr(self.node.as_const(eval_ctx),
+                                            self.attr)
+        except Exception:
+            raise Impossible()
+
+    def can_assign(self):
+        return False
+
+
+class Slice(Expr):
+    """Represents a slice object.  This must only be used as argument for
+    :class:`Subscript`.
+    """
+    fields = ('start', 'stop', 'step')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        def const(obj):
+            if obj is None:
+                return None
+            return obj.as_const(eval_ctx)
+        return slice(const(self.start), const(self.stop), const(self.step))
+
+
+class Concat(Expr):
+    """Concatenates the list of expressions provided after converting them to
+    unicode.
+    """
+    fields = ('nodes',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return ''.join(text_type(x.as_const(eval_ctx)) for x in self.nodes)
+
+
+class Compare(Expr):
+    """Compares an expression with some other expressions.  `ops` must be a
+    list of :class:`Operand`\\s.
+    """
+    fields = ('expr', 'ops')
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        result = value = self.expr.as_const(eval_ctx)
+        try:
+            for op in self.ops:
+                new_value = op.expr.as_const(eval_ctx)
+                result = _cmpop_to_func[op.op](value, new_value)
+                value = new_value
+        except Exception:
+            raise Impossible()
+        return result
+
+
+class Operand(Helper):
+    """Holds an operator and an expression."""
+    fields = ('op', 'expr')
+
+if __debug__:
+    Operand.__doc__ += '\nThe following operators are available: ' + \
+        ', '.join(sorted('``%s``' % x for x in set(_binop_to_func) |
+                  set(_uaop_to_func) | set(_cmpop_to_func)))
+
+
+class Mul(BinExpr):
+    """Multiplies the left with the right node."""
+    operator = '*'
+
+
+class Div(BinExpr):
+    """Divides the left by the right node."""
+    operator = '/'
+
+
+class FloorDiv(BinExpr):
+    """Divides the left by the right node and truncates conver the
+    result into an integer by truncating.
+    """
+    operator = '//'
+
+
+class Add(BinExpr):
+    """Add the left to the right node."""
+    operator = '+'
+
+
+class Sub(BinExpr):
+    """Subtract the right from the left node."""
+    operator = '-'
+
+
+class Mod(BinExpr):
+    """Left modulo right."""
+    operator = '%'
+
+
+class Pow(BinExpr):
+    """Left to the power of right."""
+    operator = '**'
+
+
+class And(BinExpr):
+    """Short circuited AND."""
+    operator = 'and'
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) and self.right.as_const(eval_ctx)
+
+
+class Or(BinExpr):
+    """Short circuited OR."""
+    operator = 'or'
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) or self.right.as_const(eval_ctx)
+
+
+class Not(UnaryExpr):
+    """Negate the expression."""
+    operator = 'not'
+
+
+class Neg(UnaryExpr):
+    """Make the expression negative."""
+    operator = '-'
+
+
+class Pos(UnaryExpr):
+    """Make the expression positive (noop for most expressions)"""
+    operator = '+'
+
+
+# Helpers for extensions
+
+
+class EnvironmentAttribute(Expr):
+    """Loads an attribute from the environment object.  This is useful for
+    extensions that want to call a callback stored on the environment.
+    """
+    fields = ('name',)
+
+
+class ExtensionAttribute(Expr):
+    """Returns the attribute of an extension bound to the environment.
+    The identifier is the identifier of the :class:`Extension`.
+
+    This node is usually constructed by calling the
+    :meth:`~jinja2.ext.Extension.attr` method on an extension.
+    """
+    fields = ('identifier', 'name')
+
+
+class ImportedName(Expr):
+    """If created with an import name the import name is returned on node
+    access.  For example ``ImportedName('cgi.escape')`` returns the `escape`
+    function from the cgi module on evaluation.  Imports are optimized by the
+    compiler so there is no need to assign them to local variables.
+    """
+    fields = ('importname',)
+
+
+class InternalName(Expr):
+    """An internal name in the compiler.  You cannot create these nodes
+    yourself but the parser provides a
+    :meth:`~jinja2.parser.Parser.free_identifier` method that creates
+    a new identifier for you.  This identifier is not available from the
+    template and is not threated specially by the compiler.
+    """
+    fields = ('name',)
+
+    def __init__(self):
+        raise TypeError('Can\'t create internal names.  Use the '
+                        '`free_identifier` method on a parser.')
+
+
+class MarkSafe(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`)."""
+    fields = ('expr',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return Markup(self.expr.as_const(eval_ctx))
+
+
+class MarkSafeIfAutoescape(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`) but
+    only if autoescaping is active.
+
+    .. versionadded:: 2.5
+    """
+    fields = ('expr',)
+
+    def as_const(self, eval_ctx=None):
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        expr = self.expr.as_const(eval_ctx)
+        if eval_ctx.autoescape:
+            return Markup(expr)
+        return expr
+
+
+class ContextReference(Expr):
+    """Returns the current template context.  It can be used like a
+    :class:`Name` node, with a ``'load'`` ctx and will return the
+    current :class:`~jinja2.runtime.Context` object.
+
+    Here an example that assigns the current template name to a
+    variable named `foo`::
+
+        Assign(Name('foo', ctx='store'),
+               Getattr(ContextReference(), 'name'))
+    """
+
+
+class Continue(Stmt):
+    """Continue a loop."""
+
+
+class Break(Stmt):
+    """Break a loop."""
+
+
+class Scope(Stmt):
+    """An artificial scope."""
+    fields = ('body',)
+
+
+class OverlayScope(Stmt):
+    """An overlay scope for extensions.  This is a largely unoptimized scope
+    that however can be used to introduce completely arbitrary variables into
+    a sub scope from a dictionary or dictionary like object.  The `context`
+    field has to evaluate to a dictionary object.
+
+    Example usage::
+
+        OverlayScope(context=self.call_method('get_context'),
+                     body=[...])
+
+    .. versionadded:: 2.10
+    """
+    fields = ('context', 'body')
+
+
+class EvalContextModifier(Stmt):
+    """Modifies the eval context.  For each option that should be modified,
+    a :class:`Keyword` has to be added to the :attr:`options` list.
+
+    Example to change the `autoescape` setting::
+
+        EvalContextModifier(options=[Keyword('autoescape', Const(True))])
+    """
+    fields = ('options',)
+
+
+class ScopedEvalContextModifier(EvalContextModifier):
+    """Modifies the eval context and reverts it later.  Works exactly like
+    :class:`EvalContextModifier` but will only modify the
+    :class:`~jinja2.nodes.EvalContext` for nodes in the :attr:`body`.
+    """
+    fields = ('body',)
+
+
+# make sure nobody creates custom nodes
+def _failing_new(*args, **kwargs):
+    raise TypeError('can\'t create custom node types')
+NodeType.__new__ = staticmethod(_failing_new); del _failing_new
diff --git a/python/jinja2/optimizer.py b/python/jinja2/optimizer.py
new file mode 100644
index 0000000..65ab3ce
--- /dev/null
+++ b/python/jinja2/optimizer.py
@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.optimizer
+    ~~~~~~~~~~~~~~~~
+
+    The jinja optimizer is currently trying to constant fold a few expressions
+    and modify the AST in place so that it should be easier to evaluate it.
+
+    Because the AST does not contain all the scoping information and the
+    compiler has to find that out, we cannot do all the optimizations we
+    want.  For example loop unrolling doesn't work because unrolled loops would
+    have a different scoping.
+
+    The solution would be a second syntax tree that has the scoping rules stored.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+from jinja2 import nodes
+from jinja2.visitor import NodeTransformer
+
+
+def optimize(node, environment):
+    """The context hint can be used to perform an static optimization
+    based on the context given."""
+    optimizer = Optimizer(environment)
+    return optimizer.visit(node)
+
+
+class Optimizer(NodeTransformer):
+
+    def __init__(self, environment):
+        self.environment = environment
+
+    def fold(self, node, eval_ctx=None):
+        """Do constant folding."""
+        node = self.generic_visit(node)
+        try:
+            return nodes.Const.from_untrusted(node.as_const(eval_ctx),
+                                              lineno=node.lineno,
+                                              environment=self.environment)
+        except nodes.Impossible:
+            return node
+
+    visit_Add = visit_Sub = visit_Mul = visit_Div = visit_FloorDiv = \
+    visit_Pow = visit_Mod = visit_And = visit_Or = visit_Pos = visit_Neg = \
+    visit_Not = visit_Compare = visit_Getitem = visit_Getattr = visit_Call = \
+    visit_Filter = visit_Test = visit_CondExpr = fold
+    del fold
diff --git a/python/jinja2/parser.py b/python/jinja2/parser.py
new file mode 100644
index 0000000..ed00d97
--- /dev/null
+++ b/python/jinja2/parser.py
@@ -0,0 +1,903 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.parser
+    ~~~~~~~~~~~~~
+
+    Implements the template parser.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+from jinja2 import nodes
+from jinja2.exceptions import TemplateSyntaxError, TemplateAssertionError
+from jinja2.lexer import describe_token, describe_token_expr
+from jinja2._compat import imap
+
+
+_statement_keywords = frozenset(['for', 'if', 'block', 'extends', 'print',
+                                 'macro', 'include', 'from', 'import',
+                                 'set', 'with', 'autoescape'])
+_compare_operators = frozenset(['eq', 'ne', 'lt', 'lteq', 'gt', 'gteq'])
+
+_math_nodes = {
+    'add': nodes.Add,
+    'sub': nodes.Sub,
+    'mul': nodes.Mul,
+    'div': nodes.Div,
+    'floordiv': nodes.FloorDiv,
+    'mod': nodes.Mod,
+}
+
+
+class Parser(object):
+    """This is the central parsing class Jinja2 uses.  It's passed to
+    extensions and can be used to parse expressions or statements.
+    """
+
+    def __init__(self, environment, source, name=None, filename=None,
+                 state=None):
+        self.environment = environment
+        self.stream = environment._tokenize(source, name, filename, state)
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.extensions = {}
+        for extension in environment.iter_extensions():
+            for tag in extension.tags:
+                self.extensions[tag] = extension.parse
+        self._last_identifier = 0
+        self._tag_stack = []
+        self._end_token_stack = []
+
+    def fail(self, msg, lineno=None, exc=TemplateSyntaxError):
+        """Convenience method that raises `exc` with the message, passed
+        line number or last line number as well as the current name and
+        filename.
+        """
+        if lineno is None:
+            lineno = self.stream.current.lineno
+        raise exc(msg, lineno, self.name, self.filename)
+
+    def _fail_ut_eof(self, name, end_token_stack, lineno):
+        expected = []
+        for exprs in end_token_stack:
+            expected.extend(imap(describe_token_expr, exprs))
+        if end_token_stack:
+            currently_looking = ' or '.join(
+                "'%s'" % describe_token_expr(expr)
+                for expr in end_token_stack[-1])
+        else:
+            currently_looking = None
+
+        if name is None:
+            message = ['Unexpected end of template.']
+        else:
+            message = ['Encountered unknown tag \'%s\'.' % name]
+
+        if currently_looking:
+            if name is not None and name in expected:
+                message.append('You probably made a nesting mistake. Jinja '
+                               'is expecting this tag, but currently looking '
+                               'for %s.' % currently_looking)
+            else:
+                message.append('Jinja was looking for the following tags: '
+                               '%s.' % currently_looking)
+
+        if self._tag_stack:
+            message.append('The innermost block that needs to be '
+                           'closed is \'%s\'.' % self._tag_stack[-1])
+
+        self.fail(' '.join(message), lineno)
+
+    def fail_unknown_tag(self, name, lineno=None):
+        """Called if the parser encounters an unknown tag.  Tries to fail
+        with a human readable error message that could help to identify
+        the problem.
+        """
+        return self._fail_ut_eof(name, self._end_token_stack, lineno)
+
+    def fail_eof(self, end_tokens=None, lineno=None):
+        """Like fail_unknown_tag but for end of template situations."""
+        stack = list(self._end_token_stack)
+        if end_tokens is not None:
+            stack.append(end_tokens)
+        return self._fail_ut_eof(None, stack, lineno)
+
+    def is_tuple_end(self, extra_end_rules=None):
+        """Are we at the end of a tuple?"""
+        if self.stream.current.type in ('variable_end', 'block_end', 'rparen'):
+            return True
+        elif extra_end_rules is not None:
+            return self.stream.current.test_any(extra_end_rules)
+        return False
+
+    def free_identifier(self, lineno=None):
+        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
+        self._last_identifier += 1
+        rv = object.__new__(nodes.InternalName)
+        nodes.Node.__init__(rv, 'fi%d' % self._last_identifier, lineno=lineno)
+        return rv
+
+    def parse_statement(self):
+        """Parse a single statement."""
+        token = self.stream.current
+        if token.type != 'name':
+            self.fail('tag name expected', token.lineno)
+        self._tag_stack.append(token.value)
+        pop_tag = True
+        try:
+            if token.value in _statement_keywords:
+                return getattr(self, 'parse_' + self.stream.current.value)()
+            if token.value == 'call':
+                return self.parse_call_block()
+            if token.value == 'filter':
+                return self.parse_filter_block()
+            ext = self.extensions.get(token.value)
+            if ext is not None:
+                return ext(self)
+
+            # did not work out, remove the token we pushed by accident
+            # from the stack so that the unknown tag fail function can
+            # produce a proper error message.
+            self._tag_stack.pop()
+            pop_tag = False
+            self.fail_unknown_tag(token.value, token.lineno)
+        finally:
+            if pop_tag:
+                self._tag_stack.pop()
+
+    def parse_statements(self, end_tokens, drop_needle=False):
+        """Parse multiple statements into a list until one of the end tokens
+        is reached.  This is used to parse the body of statements as it also
+        parses template data if appropriate.  The parser checks first if the
+        current token is a colon and skips it if there is one.  Then it checks
+        for the block end and parses until if one of the `end_tokens` is
+        reached.  Per default the active token in the stream at the end of
+        the call is the matched end token.  If this is not wanted `drop_needle`
+        can be set to `True` and the end token is removed.
+        """
+        # the first token may be a colon for python compatibility
+        self.stream.skip_if('colon')
+
+        # in the future it would be possible to add whole code sections
+        # by adding some sort of end of statement token and parsing those here.
+        self.stream.expect('block_end')
+        result = self.subparse(end_tokens)
+
+        # we reached the end of the template too early, the subparser
+        # does not check for this, so we do that now
+        if self.stream.current.type == 'eof':
+            self.fail_eof(end_tokens)
+
+        if drop_needle:
+            next(self.stream)
+        return result
+
+    def parse_set(self):
+        """Parse an assign statement."""
+        lineno = next(self.stream).lineno
+        target = self.parse_assign_target(with_namespace=True)
+        if self.stream.skip_if('assign'):
+            expr = self.parse_tuple()
+            return nodes.Assign(target, expr, lineno=lineno)
+        filter_node = self.parse_filter(None)
+        body = self.parse_statements(('name:endset',),
+                                     drop_needle=True)
+        return nodes.AssignBlock(target, filter_node, body, lineno=lineno)
+
+    def parse_for(self):
+        """Parse a for loop."""
+        lineno = self.stream.expect('name:for').lineno
+        target = self.parse_assign_target(extra_end_rules=('name:in',))
+        self.stream.expect('name:in')
+        iter = self.parse_tuple(with_condexpr=False,
+                                extra_end_rules=('name:recursive',))
+        test = None
+        if self.stream.skip_if('name:if'):
+            test = self.parse_expression()
+        recursive = self.stream.skip_if('name:recursive')
+        body = self.parse_statements(('name:endfor', 'name:else'))
+        if next(self.stream).value == 'endfor':
+            else_ = []
+        else:
+            else_ = self.parse_statements(('name:endfor',), drop_needle=True)
+        return nodes.For(target, iter, body, else_, test,
+                         recursive, lineno=lineno)
+
+    def parse_if(self):
+        """Parse an if construct."""
+        node = result = nodes.If(lineno=self.stream.expect('name:if').lineno)
+        while 1:
+            node.test = self.parse_tuple(with_condexpr=False)
+            node.body = self.parse_statements(('name:elif', 'name:else',
+                                               'name:endif'))
+            node.elif_ = []
+            node.else_ = []
+            token = next(self.stream)
+            if token.test('name:elif'):
+                node = nodes.If(lineno=self.stream.current.lineno)
+                result.elif_.append(node)
+                continue
+            elif token.test('name:else'):
+                result.else_ = self.parse_statements(('name:endif',),
+                                                     drop_needle=True)
+            break
+        return result
+
+    def parse_with(self):
+        node = nodes.With(lineno=next(self.stream).lineno)
+        targets = []
+        values = []
+        while self.stream.current.type != 'block_end':
+            lineno = self.stream.current.lineno
+            if targets:
+                self.stream.expect('comma')
+            target = self.parse_assign_target()
+            target.set_ctx('param')
+            targets.append(target)
+            self.stream.expect('assign')
+            values.append(self.parse_expression())
+        node.targets = targets
+        node.values = values
+        node.body = self.parse_statements(('name:endwith',),
+                                          drop_needle=True)
+        return node
+
+    def parse_autoescape(self):
+        node = nodes.ScopedEvalContextModifier(lineno=next(self.stream).lineno)
+        node.options = [
+            nodes.Keyword('autoescape', self.parse_expression())
+        ]
+        node.body = self.parse_statements(('name:endautoescape',),
+                                            drop_needle=True)
+        return nodes.Scope([node])
+
+    def parse_block(self):
+        node = nodes.Block(lineno=next(self.stream).lineno)
+        node.name = self.stream.expect('name').value
+        node.scoped = self.stream.skip_if('name:scoped')
+
+        # common problem people encounter when switching from django
+        # to jinja.  we do not support hyphens in block names, so let's
+        # raise a nicer error message in that case.
+        if self.stream.current.type == 'sub':
+            self.fail('Block names in Jinja have to be valid Python '
+                      'identifiers and may not contain hyphens, use an '
+                      'underscore instead.')
+
+        node.body = self.parse_statements(('name:endblock',), drop_needle=True)
+        self.stream.skip_if('name:' + node.name)
+        return node
+
+    def parse_extends(self):
+        node = nodes.Extends(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        return node
+
+    def parse_import_context(self, node, default):
+        if self.stream.current.test_any('name:with', 'name:without') and \
+           self.stream.look().test('name:context'):
+            node.with_context = next(self.stream).value == 'with'
+            self.stream.skip()
+        else:
+            node.with_context = default
+        return node
+
+    def parse_include(self):
+        node = nodes.Include(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        if self.stream.current.test('name:ignore') and \
+           self.stream.look().test('name:missing'):
+            node.ignore_missing = True
+            self.stream.skip(2)
+        else:
+            node.ignore_missing = False
+        return self.parse_import_context(node, True)
+
+    def parse_import(self):
+        node = nodes.Import(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect('name:as')
+        node.target = self.parse_assign_target(name_only=True).name
+        return self.parse_import_context(node, False)
+
+    def parse_from(self):
+        node = nodes.FromImport(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect('name:import')
+        node.names = []
+
+        def parse_context():
+            if self.stream.current.value in ('with', 'without') and \
+               self.stream.look().test('name:context'):
+                node.with_context = next(self.stream).value == 'with'
+                self.stream.skip()
+                return True
+            return False
+
+        while 1:
+            if node.names:
+                self.stream.expect('comma')
+            if self.stream.current.type == 'name':
+                if parse_context():
+                    break
+                target = self.parse_assign_target(name_only=True)
+                if target.name.startswith('_'):
+                    self.fail('names starting with an underline can not '
+                              'be imported', target.lineno,
+                              exc=TemplateAssertionError)
+                if self.stream.skip_if('name:as'):
+                    alias = self.parse_assign_target(name_only=True)
+                    node.names.append((target.name, alias.name))
+                else:
+                    node.names.append(target.name)
+                if parse_context() or self.stream.current.type != 'comma':
+                    break
+            else:
+                self.stream.expect('name')
+        if not hasattr(node, 'with_context'):
+            node.with_context = False
+        return node
+
+    def parse_signature(self, node):
+        node.args = args = []
+        node.defaults = defaults = []
+        self.stream.expect('lparen')
+        while self.stream.current.type != 'rparen':
+            if args:
+                self.stream.expect('comma')
+            arg = self.parse_assign_target(name_only=True)
+            arg.set_ctx('param')
+            if self.stream.skip_if('assign'):
+                defaults.append(self.parse_expression())
+            elif defaults:
+                self.fail('non-default argument follows default argument')
+            args.append(arg)
+        self.stream.expect('rparen')
+
+    def parse_call_block(self):
+        node = nodes.CallBlock(lineno=next(self.stream).lineno)
+        if self.stream.current.type == 'lparen':
+            self.parse_signature(node)
+        else:
+            node.args = []
+            node.defaults = []
+
+        node.call = self.parse_expression()
+        if not isinstance(node.call, nodes.Call):
+            self.fail('expected call', node.lineno)
+        node.body = self.parse_statements(('name:endcall',), drop_needle=True)
+        return node
+
+    def parse_filter_block(self):
+        node = nodes.FilterBlock(lineno=next(self.stream).lineno)
+        node.filter = self.parse_filter(None, start_inline=True)
+        node.body = self.parse_statements(('name:endfilter',),
+                                          drop_needle=True)
+        return node
+
+    def parse_macro(self):
+        node = nodes.Macro(lineno=next(self.stream).lineno)
+        node.name = self.parse_assign_target(name_only=True).name
+        self.parse_signature(node)
+        node.body = self.parse_statements(('name:endmacro',),
+                                          drop_needle=True)
+        return node
+
+    def parse_print(self):
+        node = nodes.Output(lineno=next(self.stream).lineno)
+        node.nodes = []
+        while self.stream.current.type != 'block_end':
+            if node.nodes:
+                self.stream.expect('comma')
+            node.nodes.append(self.parse_expression())
+        return node
+
+    def parse_assign_target(self, with_tuple=True, name_only=False,
+                            extra_end_rules=None, with_namespace=False):
+        """Parse an assignment target.  As Jinja2 allows assignments to
+        tuples, this function can parse all allowed assignment targets.  Per
+        default assignments to tuples are parsed, that can be disable however
+        by setting `with_tuple` to `False`.  If only assignments to names are
+        wanted `name_only` can be set to `True`.  The `extra_end_rules`
+        parameter is forwarded to the tuple parsing function.  If
+        `with_namespace` is enabled, a namespace assignment may be parsed.
+        """
+        if with_namespace and self.stream.look().type == 'dot':
+            token = self.stream.expect('name')
+            next(self.stream)  # dot
+            attr = self.stream.expect('name')
+            target = nodes.NSRef(token.value, attr.value, lineno=token.lineno)
+        elif name_only:
+            token = self.stream.expect('name')
+            target = nodes.Name(token.value, 'store', lineno=token.lineno)
+        else:
+            if with_tuple:
+                target = self.parse_tuple(simplified=True,
+                                          extra_end_rules=extra_end_rules)
+            else:
+                target = self.parse_primary()
+            target.set_ctx('store')
+        if not target.can_assign():
+            self.fail('can\'t assign to %r' % target.__class__.
+                      __name__.lower(), target.lineno)
+        return target
+
+    def parse_expression(self, with_condexpr=True):
+        """Parse an expression.  Per default all expressions are parsed, if
+        the optional `with_condexpr` parameter is set to `False` conditional
+        expressions are not parsed.
+        """
+        if with_condexpr:
+            return self.parse_condexpr()
+        return self.parse_or()
+
+    def parse_condexpr(self):
+        lineno = self.stream.current.lineno
+        expr1 = self.parse_or()
+        while self.stream.skip_if('name:if'):
+            expr2 = self.parse_or()
+            if self.stream.skip_if('name:else'):
+                expr3 = self.parse_condexpr()
+            else:
+                expr3 = None
+            expr1 = nodes.CondExpr(expr2, expr1, expr3, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return expr1
+
+    def parse_or(self):
+        lineno = self.stream.current.lineno
+        left = self.parse_and()
+        while self.stream.skip_if('name:or'):
+            right = self.parse_and()
+            left = nodes.Or(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_and(self):
+        lineno = self.stream.current.lineno
+        left = self.parse_not()
+        while self.stream.skip_if('name:and'):
+            right = self.parse_not()
+            left = nodes.And(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_not(self):
+        if self.stream.current.test('name:not'):
+            lineno = next(self.stream).lineno
+            return nodes.Not(self.parse_not(), lineno=lineno)
+        return self.parse_compare()
+
+    def parse_compare(self):
+        lineno = self.stream.current.lineno
+        expr = self.parse_math1()
+        ops = []
+        while 1:
+            token_type = self.stream.current.type
+            if token_type in _compare_operators:
+                next(self.stream)
+                ops.append(nodes.Operand(token_type, self.parse_math1()))
+            elif self.stream.skip_if('name:in'):
+                ops.append(nodes.Operand('in', self.parse_math1()))
+            elif (self.stream.current.test('name:not') and
+                  self.stream.look().test('name:in')):
+                self.stream.skip(2)
+                ops.append(nodes.Operand('notin', self.parse_math1()))
+            else:
+                break
+            lineno = self.stream.current.lineno
+        if not ops:
+            return expr
+        return nodes.Compare(expr, ops, lineno=lineno)
+
+    def parse_math1(self):
+        lineno = self.stream.current.lineno
+        left = self.parse_concat()
+        while self.stream.current.type in ('add', 'sub'):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_concat()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_concat(self):
+        lineno = self.stream.current.lineno
+        args = [self.parse_math2()]
+        while self.stream.current.type == 'tilde':
+            next(self.stream)
+            args.append(self.parse_math2())
+        if len(args) == 1:
+            return args[0]
+        return nodes.Concat(args, lineno=lineno)
+
+    def parse_math2(self):
+        lineno = self.stream.current.lineno
+        left = self.parse_pow()
+        while self.stream.current.type in ('mul', 'div', 'floordiv', 'mod'):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_pow()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_pow(self):
+        lineno = self.stream.current.lineno
+        left = self.parse_unary()
+        while self.stream.current.type == 'pow':
+            next(self.stream)
+            right = self.parse_unary()
+            left = nodes.Pow(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_unary(self, with_filter=True):
+        token_type = self.stream.current.type
+        lineno = self.stream.current.lineno
+        if token_type == 'sub':
+            next(self.stream)
+            node = nodes.Neg(self.parse_unary(False), lineno=lineno)
+        elif token_type == 'add':
+            next(self.stream)
+            node = nodes.Pos(self.parse_unary(False), lineno=lineno)
+        else:
+            node = self.parse_primary()
+        node = self.parse_postfix(node)
+        if with_filter:
+            node = self.parse_filter_expr(node)
+        return node
+
+    def parse_primary(self):
+        token = self.stream.current
+        if token.type == 'name':
+            if token.value in ('true', 'false', 'True', 'False'):
+                node = nodes.Const(token.value in ('true', 'True'),
+                                   lineno=token.lineno)
+            elif token.value in ('none', 'None'):
+                node = nodes.Const(None, lineno=token.lineno)
+            else:
+                node = nodes.Name(token.value, 'load', lineno=token.lineno)
+            next(self.stream)
+        elif token.type == 'string':
+            next(self.stream)
+            buf = [token.value]
+            lineno = token.lineno
+            while self.stream.current.type == 'string':
+                buf.append(self.stream.current.value)
+                next(self.stream)
+            node = nodes.Const(''.join(buf), lineno=lineno)
+        elif token.type in ('integer', 'float'):
+            next(self.stream)
+            node = nodes.Const(token.value, lineno=token.lineno)
+        elif token.type == 'lparen':
+            next(self.stream)
+            node = self.parse_tuple(explicit_parentheses=True)
+            self.stream.expect('rparen')
+        elif token.type == 'lbracket':
+            node = self.parse_list()
+        elif token.type == 'lbrace':
+            node = self.parse_dict()
+        else:
+            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
+        return node
+
+    def parse_tuple(self, simplified=False, with_condexpr=True,
+                    extra_end_rules=None, explicit_parentheses=False):
+        """Works like `parse_expression` but if multiple expressions are
+        delimited by a comma a :class:`~jinja2.nodes.Tuple` node is created.
+        This method could also return a regular expression instead of a tuple
+        if no commas where found.
+
+        The default parsing mode is a full tuple.  If `simplified` is `True`
+        only names and literals are parsed.  The `no_condexpr` parameter is
+        forwarded to :meth:`parse_expression`.
+
+        Because tuples do not require delimiters and may end in a bogus comma
+        an extra hint is needed that marks the end of a tuple.  For example
+        for loops support tuples between `for` and `in`.  In that case the
+        `extra_end_rules` is set to ``['name:in']``.
+
+        `explicit_parentheses` is true if the parsing was triggered by an
+        expression in parentheses.  This is used to figure out if an empty
+        tuple is a valid expression or not.
+        """
+        lineno = self.stream.current.lineno
+        if simplified:
+            parse = self.parse_primary
+        elif with_condexpr:
+            parse = self.parse_expression
+        else:
+            parse = lambda: self.parse_expression(with_condexpr=False)
+        args = []
+        is_tuple = False
+        while 1:
+            if args:
+                self.stream.expect('comma')
+            if self.is_tuple_end(extra_end_rules):
+                break
+            args.append(parse())
+            if self.stream.current.type == 'comma':
+                is_tuple = True
+            else:
+                break
+            lineno = self.stream.current.lineno
+
+        if not is_tuple:
+            if args:
+                return args[0]
+
+            # if we don't have explicit parentheses, an empty tuple is
+            # not a valid expression.  This would mean nothing (literally
+            # nothing) in the spot of an expression would be an empty
+            # tuple.
+            if not explicit_parentheses:
+                self.fail('Expected an expression, got \'%s\'' %
+                          describe_token(self.stream.current))
+
+        return nodes.Tuple(args, 'load', lineno=lineno)
+
+    def parse_list(self):
+        token = self.stream.expect('lbracket')
+        items = []
+        while self.stream.current.type != 'rbracket':
+            if items:
+                self.stream.expect('comma')
+            if self.stream.current.type == 'rbracket':
+                break
+            items.append(self.parse_expression())
+        self.stream.expect('rbracket')
+        return nodes.List(items, lineno=token.lineno)
+
+    def parse_dict(self):
+        token = self.stream.expect('lbrace')
+        items = []
+        while self.stream.current.type != 'rbrace':
+            if items:
+                self.stream.expect('comma')
+            if self.stream.current.type == 'rbrace':
+                break
+            key = self.parse_expression()
+            self.stream.expect('colon')
+            value = self.parse_expression()
+            items.append(nodes.Pair(key, value, lineno=key.lineno))
+        self.stream.expect('rbrace')
+        return nodes.Dict(items, lineno=token.lineno)
+
+    def parse_postfix(self, node):
+        while 1:
+            token_type = self.stream.current.type
+            if token_type == 'dot' or token_type == 'lbracket':
+                node = self.parse_subscript(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == 'lparen':
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_filter_expr(self, node):
+        while 1:
+            token_type = self.stream.current.type
+            if token_type == 'pipe':
+                node = self.parse_filter(node)
+            elif token_type == 'name' and self.stream.current.value == 'is':
+                node = self.parse_test(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == 'lparen':
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_subscript(self, node):
+        token = next(self.stream)
+        if token.type == 'dot':
+            attr_token = self.stream.current
+            next(self.stream)
+            if attr_token.type == 'name':
+                return nodes.Getattr(node, attr_token.value, 'load',
+                                     lineno=token.lineno)
+            elif attr_token.type != 'integer':
+                self.fail('expected name or number', attr_token.lineno)
+            arg = nodes.Const(attr_token.value, lineno=attr_token.lineno)
+            return nodes.Getitem(node, arg, 'load', lineno=token.lineno)
+        if token.type == 'lbracket':
+            args = []
+            while self.stream.current.type != 'rbracket':
+                if args:
+                    self.stream.expect('comma')
+                args.append(self.parse_subscribed())
+            self.stream.expect('rbracket')
+            if len(args) == 1:
+                arg = args[0]
+            else:
+                arg = nodes.Tuple(args, 'load', lineno=token.lineno)
+            return nodes.Getitem(node, arg, 'load', lineno=token.lineno)
+        self.fail('expected subscript expression', self.lineno)
+
+    def parse_subscribed(self):
+        lineno = self.stream.current.lineno
+
+        if self.stream.current.type == 'colon':
+            next(self.stream)
+            args = [None]
+        else:
+            node = self.parse_expression()
+            if self.stream.current.type != 'colon':
+                return node
+            next(self.stream)
+            args = [node]
+
+        if self.stream.current.type == 'colon':
+            args.append(None)
+        elif self.stream.current.type not in ('rbracket', 'comma'):
+            args.append(self.parse_expression())
+        else:
+            args.append(None)
+
+        if self.stream.current.type == 'colon':
+            next(self.stream)
+            if self.stream.current.type not in ('rbracket', 'comma'):
+                args.append(self.parse_expression())
+            else:
+                args.append(None)
+        else:
+            args.append(None)
+
+        return nodes.Slice(lineno=lineno, *args)
+
+    def parse_call(self, node):
+        token = self.stream.expect('lparen')
+        args = []
+        kwargs = []
+        dyn_args = dyn_kwargs = None
+        require_comma = False
+
+        def ensure(expr):
+            if not expr:
+                self.fail('invalid syntax for function call expression',
+                          token.lineno)
+
+        while self.stream.current.type != 'rparen':
+            if require_comma:
+                self.stream.expect('comma')
+                # support for trailing comma
+                if self.stream.current.type == 'rparen':
+                    break
+            if self.stream.current.type == 'mul':
+                ensure(dyn_args is None and dyn_kwargs is None)
+                next(self.stream)
+                dyn_args = self.parse_expression()
+            elif self.stream.current.type == 'pow':
+                ensure(dyn_kwargs is None)
+                next(self.stream)
+                dyn_kwargs = self.parse_expression()
+            else:
+                ensure(dyn_args is None and dyn_kwargs is None)
+                if self.stream.current.type == 'name' and \
+                   self.stream.look().type == 'assign':
+                    key = self.stream.current.value
+                    self.stream.skip(2)
+                    value = self.parse_expression()
+                    kwargs.append(nodes.Keyword(key, value,
+                                                lineno=value.lineno))
+                else:
+                    ensure(not kwargs)
+                    args.append(self.parse_expression())
+
+            require_comma = True
+        self.stream.expect('rparen')
+
+        if node is None:
+            return args, kwargs, dyn_args, dyn_kwargs
+        return nodes.Call(node, args, kwargs, dyn_args, dyn_kwargs,
+                          lineno=token.lineno)
+
+    def parse_filter(self, node, start_inline=False):
+        while self.stream.current.type == 'pipe' or start_inline:
+            if not start_inline:
+                next(self.stream)
+            token = self.stream.expect('name')
+            name = token.value
+            while self.stream.current.type == 'dot':
+                next(self.stream)
+                name += '.' + self.stream.expect('name').value
+            if self.stream.current.type == 'lparen':
+                args, kwargs, dyn_args, dyn_kwargs = self.parse_call(None)
+            else:
+                args = []
+                kwargs = []
+                dyn_args = dyn_kwargs = None
+            node = nodes.Filter(node, name, args, kwargs, dyn_args,
+                                dyn_kwargs, lineno=token.lineno)
+            start_inline = False
+        return node
+
+    def parse_test(self, node):
+        token = next(self.stream)
+        if self.stream.current.test('name:not'):
+            next(self.stream)
+            negated = True
+        else:
+            negated = False
+        name = self.stream.expect('name').value
+        while self.stream.current.type == 'dot':
+            next(self.stream)
+            name += '.' + self.stream.expect('name').value
+        dyn_args = dyn_kwargs = None
+        kwargs = []
+        if self.stream.current.type == 'lparen':
+            args, kwargs, dyn_args, dyn_kwargs = self.parse_call(None)
+        elif (self.stream.current.type in ('name', 'string', 'integer',
+                                           'float', 'lparen', 'lbracket',
+                                           'lbrace') and not
+              self.stream.current.test_any('name:else', 'name:or',
+                                           'name:and')):
+            if self.stream.current.test('name:is'):
+                self.fail('You cannot chain multiple tests with is')
+            args = [self.parse_primary()]
+        else:
+            args = []
+        node = nodes.Test(node, name, args, kwargs, dyn_args,
+                          dyn_kwargs, lineno=token.lineno)
+        if negated:
+            node = nodes.Not(node, lineno=token.lineno)
+        return node
+
+    def subparse(self, end_tokens=None):
+        body = []
+        data_buffer = []
+        add_data = data_buffer.append
+
+        if end_tokens is not None:
+            self._end_token_stack.append(end_tokens)
+
+        def flush_data():
+            if data_buffer:
+                lineno = data_buffer[0].lineno
+                body.append(nodes.Output(data_buffer[:], lineno=lineno))
+                del data_buffer[:]
+
+        try:
+            while self.stream:
+                token = self.stream.current
+                if token.type == 'data':
+                    if token.value:
+                        add_data(nodes.TemplateData(token.value,
+                                                    lineno=token.lineno))
+                    next(self.stream)
+                elif token.type == 'variable_begin':
+                    next(self.stream)
+                    add_data(self.parse_tuple(with_condexpr=True))
+                    self.stream.expect('variable_end')
+                elif token.type == 'block_begin':
+                    flush_data()
+                    next(self.stream)
+                    if end_tokens is not None and \
+                       self.stream.current.test_any(*end_tokens):
+                        return body
+                    rv = self.parse_statement()
+                    if isinstance(rv, list):
+                        body.extend(rv)
+                    else:
+                        body.append(rv)
+                    self.stream.expect('block_end')
+                else:
+                    raise AssertionError('internal parsing error')
+
+            flush_data()
+        finally:
+            if end_tokens is not None:
+                self._end_token_stack.pop()
+
+        return body
+
+    def parse(self):
+        """Parse the whole template into a `Template` node."""
+        result = nodes.Template(self.subparse(), lineno=1)
+        result.set_environment(self.environment)
+        return result
diff --git a/python/jinja2/runtime.py b/python/jinja2/runtime.py
new file mode 100644
index 0000000..f9d7a68
--- /dev/null
+++ b/python/jinja2/runtime.py
@@ -0,0 +1,813 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.runtime
+    ~~~~~~~~~~~~~~
+
+    Runtime helpers.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+import sys
+
+from itertools import chain
+from types import MethodType
+
+from jinja2.nodes import EvalContext, _context_function_types
+from jinja2.utils import Markup, soft_unicode, escape, missing, concat, \
+     internalcode, object_type_repr, evalcontextfunction, Namespace
+from jinja2.exceptions import UndefinedError, TemplateRuntimeError, \
+     TemplateNotFound
+from jinja2._compat import imap, text_type, iteritems, \
+     implements_iterator, implements_to_string, string_types, PY2, \
+     with_metaclass
+
+
+# these variables are exported to the template runtime
+__all__ = ['LoopContext', 'TemplateReference', 'Macro', 'Markup',
+           'TemplateRuntimeError', 'missing', 'concat', 'escape',
+           'markup_join', 'unicode_join', 'to_string', 'identity',
+           'TemplateNotFound', 'Namespace']
+
+#: the name of the function that is used to convert something into
+#: a string.  We can just use the text type here.
+to_string = text_type
+
+#: the identity function.  Useful for certain things in the environment
+identity = lambda x: x
+
+_first_iteration = object()
+_last_iteration = object()
+
+
+def markup_join(seq):
+    """Concatenation that escapes if necessary and converts to unicode."""
+    buf = []
+    iterator = imap(soft_unicode, seq)
+    for arg in iterator:
+        buf.append(arg)
+        if hasattr(arg, '__html__'):
+            return Markup(u'').join(chain(buf, iterator))
+    return concat(buf)
+
+
+def unicode_join(seq):
+    """Simple args to unicode conversion and concatenation."""
+    return concat(imap(text_type, seq))
+
+
+def new_context(environment, template_name, blocks, vars=None,
+                shared=None, globals=None, locals=None):
+    """Internal helper to for context creation."""
+    if vars is None:
+        vars = {}
+    if shared:
+        parent = vars
+    else:
+        parent = dict(globals or (), **vars)
+    if locals:
+        # if the parent is shared a copy should be created because
+        # we don't want to modify the dict passed
+        if shared:
+            parent = dict(parent)
+        for key, value in iteritems(locals):
+            if value is not missing:
+                parent[key] = value
+    return environment.context_class(environment, parent, template_name,
+                                     blocks)
+
+
+class TemplateReference(object):
+    """The `self` in templates."""
+
+    def __init__(self, context):
+        self.__context = context
+
+    def __getitem__(self, name):
+        blocks = self.__context.blocks[name]
+        return BlockReference(name, self.__context, blocks, 0)
+
+    def __repr__(self):
+        return '<%s %r>' % (
+            self.__class__.__name__,
+            self.__context.name
+        )
+
+
+def _get_func(x):
+    return getattr(x, '__func__', x)
+
+
+class ContextMeta(type):
+
+    def __new__(cls, name, bases, d):
+        rv = type.__new__(cls, name, bases, d)
+        if bases == ():
+            return rv
+
+        resolve = _get_func(rv.resolve)
+        default_resolve = _get_func(Context.resolve)
+        resolve_or_missing = _get_func(rv.resolve_or_missing)
+        default_resolve_or_missing = _get_func(Context.resolve_or_missing)
+
+        # If we have a changed resolve but no changed default or missing
+        # resolve we invert the call logic.
+        if resolve is not default_resolve and \
+           resolve_or_missing is default_resolve_or_missing:
+            rv._legacy_resolve_mode = True
+        elif resolve is default_resolve and \
+             resolve_or_missing is default_resolve_or_missing:
+            rv._fast_resolve_mode = True
+
+        return rv
+
+
+def resolve_or_missing(context, key, missing=missing):
+    if key in context.vars:
+        return context.vars[key]
+    if key in context.parent:
+        return context.parent[key]
+    return missing
+
+
+class Context(with_metaclass(ContextMeta)):
+    """The template context holds the variables of a template.  It stores the
+    values passed to the template and also the names the template exports.
+    Creating instances is neither supported nor useful as it's created
+    automatically at various stages of the template evaluation and should not
+    be created by hand.
+
+    The context is immutable.  Modifications on :attr:`parent` **must not**
+    happen and modifications on :attr:`vars` are allowed from generated
+    template code only.  Template filters and global functions marked as
+    :func:`contextfunction`\\s get the active context passed as first argument
+    and are allowed to access the context read-only.
+
+    The template context supports read only dict operations (`get`,
+    `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`,
+    `__getitem__`, `__contains__`).  Additionally there is a :meth:`resolve`
+    method that doesn't fail with a `KeyError` but returns an
+    :class:`Undefined` object for missing variables.
+    """
+    # XXX: we want to eventually make this be a deprecation warning and
+    # remove it.
+    _legacy_resolve_mode = False
+    _fast_resolve_mode = False
+
+    def __init__(self, environment, parent, name, blocks):
+        self.parent = parent
+        self.vars = {}
+        self.environment = environment
+        self.eval_ctx = EvalContext(self.environment, name)
+        self.exported_vars = set()
+        self.name = name
+
+        # create the initial mapping of blocks.  Whenever template inheritance
+        # takes place the runtime will update this mapping with the new blocks
+        # from the template.
+        self.blocks = dict((k, [v]) for k, v in iteritems(blocks))
+
+        # In case we detect the fast resolve mode we can set up an alias
+        # here that bypasses the legacy code logic.
+        if self._fast_resolve_mode:
+            self.resolve_or_missing = MethodType(resolve_or_missing, self)
+
+    def super(self, name, current):
+        """Render a parent block."""
+        try:
+            blocks = self.blocks[name]
+            index = blocks.index(current) + 1
+            blocks[index]
+        except LookupError:
+            return self.environment.undefined('there is no parent block '
+                                              'called %r.' % name,
+                                              name='super')
+        return BlockReference(name, self, blocks, index)
+
+    def get(self, key, default=None):
+        """Returns an item from the template context, if it doesn't exist
+        `default` is returned.
+        """
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def resolve(self, key):
+        """Looks up a variable like `__getitem__` or `get` but returns an
+        :class:`Undefined` object with the name of the name looked up.
+        """
+        if self._legacy_resolve_mode:
+            rv = resolve_or_missing(self, key)
+        else:
+            rv = self.resolve_or_missing(key)
+        if rv is missing:
+            return self.environment.undefined(name=key)
+        return rv
+
+    def resolve_or_missing(self, key):
+        """Resolves a variable like :meth:`resolve` but returns the
+        special `missing` value if it cannot be found.
+        """
+        if self._legacy_resolve_mode:
+            rv = self.resolve(key)
+            if isinstance(rv, Undefined):
+                rv = missing
+            return rv
+        return resolve_or_missing(self, key)
+
+    def get_exported(self):
+        """Get a new dict with the exported variables."""
+        return dict((k, self.vars[k]) for k in self.exported_vars)
+
+    def get_all(self):
+        """Return the complete context as dict including the exported
+        variables.  For optimizations reasons this might not return an
+        actual copy so be careful with using it.
+        """
+        if not self.vars:
+            return self.parent
+        if not self.parent:
+            return self.vars
+        return dict(self.parent, **self.vars)
+
+    @internalcode
+    def call(__self, __obj, *args, **kwargs):
+        """Call the callable with the arguments and keyword arguments
+        provided but inject the active context or environment as first
+        argument if the callable is a :func:`contextfunction` or
+        :func:`environmentfunction`.
+        """
+        if __debug__:
+            __traceback_hide__ = True  # noqa
+
+        # Allow callable classes to take a context
+        if hasattr(__obj, '__call__'):
+            fn = __obj.__call__
+            for fn_type in ('contextfunction',
+                            'evalcontextfunction',
+                            'environmentfunction'):
+                if hasattr(fn, fn_type):
+                    __obj = fn
+                    break
+
+        if isinstance(__obj, _context_function_types):
+            if getattr(__obj, 'contextfunction', 0):
+                args = (__self,) + args
+            elif getattr(__obj, 'evalcontextfunction', 0):
+                args = (__self.eval_ctx,) + args
+            elif getattr(__obj, 'environmentfunction', 0):
+                args = (__self.environment,) + args
+        try:
+            return __obj(*args, **kwargs)
+        except StopIteration:
+            return __self.environment.undefined('value was undefined because '
+                                                'a callable raised a '
+                                                'StopIteration exception')
+
+    def derived(self, locals=None):
+        """Internal helper function to create a derived context.  This is
+        used in situations where the system needs a new context in the same
+        template that is independent.
+        """
+        context = new_context(self.environment, self.name, {},
+                              self.get_all(), True, None, locals)
+        context.eval_ctx = self.eval_ctx
+        context.blocks.update((k, list(v)) for k, v in iteritems(self.blocks))
+        return context
+
+    def _all(meth):
+        proxy = lambda self: getattr(self.get_all(), meth)()
+        proxy.__doc__ = getattr(dict, meth).__doc__
+        proxy.__name__ = meth
+        return proxy
+
+    keys = _all('keys')
+    values = _all('values')
+    items = _all('items')
+
+    # not available on python 3
+    if PY2:
+        iterkeys = _all('iterkeys')
+        itervalues = _all('itervalues')
+        iteritems = _all('iteritems')
+    del _all
+
+    def __contains__(self, name):
+        return name in self.vars or name in self.parent
+
+    def __getitem__(self, key):
+        """Lookup a variable or raise `KeyError` if the variable is
+        undefined.
+        """
+        item = self.resolve_or_missing(key)
+        if item is missing:
+            raise KeyError(key)
+        return item
+
+    def __repr__(self):
+        return '<%s %s of %r>' % (
+            self.__class__.__name__,
+            repr(self.get_all()),
+            self.name
+        )
+
+
+# register the context as mapping if possible
+try:
+    from collections import Mapping
+    Mapping.register(Context)
+except ImportError:
+    pass
+
+
+class BlockReference(object):
+    """One block on a template reference."""
+
+    def __init__(self, name, context, stack, depth):
+        self.name = name
+        self._context = context
+        self._stack = stack
+        self._depth = depth
+
+    @property
+    def super(self):
+        """Super the block."""
+        if self._depth + 1 >= len(self._stack):
+            return self._context.environment. \
+                undefined('there is no parent block called %r.' %
+                          self.name, name='super')
+        return BlockReference(self.name, self._context, self._stack,
+                              self._depth + 1)
+
+    @internalcode
+    def __call__(self):
+        rv = concat(self._stack[self._depth](self._context))
+        if self._context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        return rv
+
+
+class LoopContextBase(object):
+    """A loop context for dynamic iteration."""
+
+    _before = _first_iteration
+    _current = _first_iteration
+    _after = _last_iteration
+    _length = None
+
+    def __init__(self, undefined, recurse=None, depth0=0):
+        self._undefined = undefined
+        self._recurse = recurse
+        self.index0 = -1
+        self.depth0 = depth0
+        self._last_checked_value = missing
+
+    def cycle(self, *args):
+        """Cycles among the arguments with the current loop index."""
+        if not args:
+            raise TypeError('no items for cycling given')
+        return args[self.index0 % len(args)]
+
+    def changed(self, *value):
+        """Checks whether the value has changed since the last call."""
+        if self._last_checked_value != value:
+            self._last_checked_value = value
+            return True
+        return False
+
+    first = property(lambda x: x.index0 == 0)
+    last = property(lambda x: x._after is _last_iteration)
+    index = property(lambda x: x.index0 + 1)
+    revindex = property(lambda x: x.length - x.index0)
+    revindex0 = property(lambda x: x.length - x.index)
+    depth = property(lambda x: x.depth0 + 1)
+
+    @property
+    def previtem(self):
+        if self._before is _first_iteration:
+            return self._undefined('there is no previous item')
+        return self._before
+
+    @property
+    def nextitem(self):
+        if self._after is _last_iteration:
+            return self._undefined('there is no next item')
+        return self._after
+
+    def __len__(self):
+        return self.length
+
+    @internalcode
+    def loop(self, iterable):
+        if self._recurse is None:
+            raise TypeError('Tried to call non recursive loop.  Maybe you '
+                            "forgot the 'recursive' modifier.")
+        return self._recurse(iterable, self._recurse, self.depth0 + 1)
+
+    # a nifty trick to enhance the error message if someone tried to call
+    # the the loop without or with too many arguments.
+    __call__ = loop
+    del loop
+
+    def __repr__(self):
+        return '<%s %r/%r>' % (
+            self.__class__.__name__,
+            self.index,
+            self.length
+        )
+
+
+class LoopContext(LoopContextBase):
+
+    def __init__(self, iterable, undefined, recurse=None, depth0=0):
+        LoopContextBase.__init__(self, undefined, recurse, depth0)
+        self._iterator = iter(iterable)
+
+        # try to get the length of the iterable early.  This must be done
+        # here because there are some broken iterators around where there
+        # __len__ is the number of iterations left (i'm looking at your
+        # listreverseiterator!).
+        try:
+            self._length = len(iterable)
+        except (TypeError, AttributeError):
+            self._length = None
+        self._after = self._safe_next()
+
+    @property
+    def length(self):
+        if self._length is None:
+            # if was not possible to get the length of the iterator when
+            # the loop context was created (ie: iterating over a generator)
+            # we have to convert the iterable into a sequence and use the
+            # length of that + the number of iterations so far.
+            iterable = tuple(self._iterator)
+            self._iterator = iter(iterable)
+            iterations_done = self.index0 + 2
+            self._length = len(iterable) + iterations_done
+        return self._length
+
+    def __iter__(self):
+        return LoopContextIterator(self)
+
+    def _safe_next(self):
+        try:
+            return next(self._iterator)
+        except StopIteration:
+            return _last_iteration
+
+
+@implements_iterator
+class LoopContextIterator(object):
+    """The iterator for a loop context."""
+    __slots__ = ('context',)
+
+    def __init__(self, context):
+        self.context = context
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        ctx = self.context
+        ctx.index0 += 1
+        if ctx._after is _last_iteration:
+            raise StopIteration()
+        ctx._before = ctx._current
+        ctx._current = ctx._after
+        ctx._after = ctx._safe_next()
+        return ctx._current, ctx
+
+
+class Macro(object):
+    """Wraps a macro function."""
+
+    def __init__(self, environment, func, name, arguments,
+                 catch_kwargs, catch_varargs, caller,
+                 default_autoescape=None):
+        self._environment = environment
+        self._func = func
+        self._argument_count = len(arguments)
+        self.name = name
+        self.arguments = arguments
+        self.catch_kwargs = catch_kwargs
+        self.catch_varargs = catch_varargs
+        self.caller = caller
+        self.explicit_caller = 'caller' in arguments
+        if default_autoescape is None:
+            default_autoescape = environment.autoescape
+        self._default_autoescape = default_autoescape
+
+    @internalcode
+    @evalcontextfunction
+    def __call__(self, *args, **kwargs):
+        # This requires a bit of explanation,  In the past we used to
+        # decide largely based on compile-time information if a macro is
+        # safe or unsafe.  While there was a volatile mode it was largely
+        # unused for deciding on escaping.  This turns out to be
+        # problemtic for macros because if a macro is safe or not not so
+        # much depends on the escape mode when it was defined but when it
+        # was used.
+        #
+        # Because however we export macros from the module system and
+        # there are historic callers that do not pass an eval context (and
+        # will continue to not pass one), we need to perform an instance
+        # check here.
+        #
+        # This is considered safe because an eval context is not a valid
+        # argument to callables otherwise anwyays.  Worst case here is
+        # that if no eval context is passed we fall back to the compile
+        # time autoescape flag.
+        if args and isinstance(args[0], EvalContext):
+            autoescape = args[0].autoescape
+            args = args[1:]
+        else:
+            autoescape = self._default_autoescape
+
+        # try to consume the positional arguments
+        arguments = list(args[:self._argument_count])
+        off = len(arguments)
+
+        # For information why this is necessary refer to the handling
+        # of caller in the `macro_body` handler in the compiler.
+        found_caller = False
+
+        # if the number of arguments consumed is not the number of
+        # arguments expected we start filling in keyword arguments
+        # and defaults.
+        if off != self._argument_count:
+            for idx, name in enumerate(self.arguments[len(arguments):]):
+                try:
+                    value = kwargs.pop(name)
+                except KeyError:
+                    value = missing
+                if name == 'caller':
+                    found_caller = True
+                arguments.append(value)
+        else:
+            found_caller = self.explicit_caller
+
+        # it's important that the order of these arguments does not change
+        # if not also changed in the compiler's `function_scoping` method.
+        # the order is caller, keyword arguments, positional arguments!
+        if self.caller and not found_caller:
+            caller = kwargs.pop('caller', None)
+            if caller is None:
+                caller = self._environment.undefined('No caller defined',
+                                                     name='caller')
+            arguments.append(caller)
+
+        if self.catch_kwargs:
+            arguments.append(kwargs)
+        elif kwargs:
+            if 'caller' in kwargs:
+                raise TypeError('macro %r was invoked with two values for '
+                                'the special caller argument.  This is '
+                                'most likely a bug.' % self.name)
+            raise TypeError('macro %r takes no keyword argument %r' %
+                            (self.name, next(iter(kwargs))))
+        if self.catch_varargs:
+            arguments.append(args[self._argument_count:])
+        elif len(args) > self._argument_count:
+            raise TypeError('macro %r takes not more than %d argument(s)' %
+                            (self.name, len(self.arguments)))
+
+        return self._invoke(arguments, autoescape)
+
+    def _invoke(self, arguments, autoescape):
+        """This method is being swapped out by the async implementation."""
+        rv = self._func(*arguments)
+        if autoescape:
+            rv = Markup(rv)
+        return rv
+
+    def __repr__(self):
+        return '<%s %s>' % (
+            self.__class__.__name__,
+            self.name is None and 'anonymous' or repr(self.name)
+        )
+
+
+@implements_to_string
+class Undefined(object):
+    """The default undefined type.  This undefined type can be printed and
+    iterated over, but every other access will raise an :exc:`jinja2.exceptions.UndefinedError`:
+
+    >>> foo = Undefined(name='foo')
+    >>> str(foo)
+    ''
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+    __slots__ = ('_undefined_hint', '_undefined_obj', '_undefined_name',
+                 '_undefined_exception')
+
+    def __init__(self, hint=None, obj=missing, name=None, exc=UndefinedError):
+        self._undefined_hint = hint
+        self._undefined_obj = obj
+        self._undefined_name = name
+        self._undefined_exception = exc
+
+    @internalcode
+    def _fail_with_undefined_error(self, *args, **kwargs):
+        """Regular callback function for undefined objects that raises an
+        `jinja2.exceptions.UndefinedError` on call.
+        """
+        if self._undefined_hint is None:
+            if self._undefined_obj is missing:
+                hint = '%r is undefined' % self._undefined_name
+            elif not isinstance(self._undefined_name, string_types):
+                hint = '%s has no element %r' % (
+                    object_type_repr(self._undefined_obj),
+                    self._undefined_name
+                )
+            else:
+                hint = '%r has no attribute %r' % (
+                    object_type_repr(self._undefined_obj),
+                    self._undefined_name
+                )
+        else:
+            hint = self._undefined_hint
+        raise self._undefined_exception(hint)
+
+    @internalcode
+    def __getattr__(self, name):
+        if name[:2] == '__':
+            raise AttributeError(name)
+        return self._fail_with_undefined_error()
+
+    __add__ = __radd__ = __mul__ = __rmul__ = __div__ = __rdiv__ = \
+        __truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = \
+        __mod__ = __rmod__ = __pos__ = __neg__ = __call__ = \
+        __getitem__ = __lt__ = __le__ = __gt__ = __ge__ = __int__ = \
+        __float__ = __complex__ = __pow__ = __rpow__ = __sub__ = \
+        __rsub__ = _fail_with_undefined_error
+
+    def __eq__(self, other):
+        return type(self) is type(other)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __hash__(self):
+        return id(type(self))
+
+    def __str__(self):
+        return u''
+
+    def __len__(self):
+        return 0
+
+    def __iter__(self):
+        if 0:
+            yield None
+
+    def __nonzero__(self):
+        return False
+    __bool__ = __nonzero__
+
+    def __repr__(self):
+        return 'Undefined'
+
+
+def make_logging_undefined(logger=None, base=None):
+    """Given a logger object this returns a new undefined class that will
+    log certain failures.  It will log iterations and printing.  If no
+    logger is given a default logger is created.
+
+    Example::
+
+        logger = logging.getLogger(__name__)
+        LoggingUndefined = make_logging_undefined(
+            logger=logger,
+            base=Undefined
+        )
+
+    .. versionadded:: 2.8
+
+    :param logger: the logger to use.  If not provided, a default logger
+                   is created.
+    :param base: the base class to add logging functionality to.  This
+                 defaults to :class:`Undefined`.
+    """
+    if logger is None:
+        import logging
+        logger = logging.getLogger(__name__)
+        logger.addHandler(logging.StreamHandler(sys.stderr))
+    if base is None:
+        base = Undefined
+
+    def _log_message(undef):
+        if undef._undefined_hint is None:
+            if undef._undefined_obj is missing:
+                hint = '%s is undefined' % undef._undefined_name
+            elif not isinstance(undef._undefined_name, string_types):
+                hint = '%s has no element %s' % (
+                    object_type_repr(undef._undefined_obj),
+                    undef._undefined_name)
+            else:
+                hint = '%s has no attribute %s' % (
+                    object_type_repr(undef._undefined_obj),
+                    undef._undefined_name)
+        else:
+            hint = undef._undefined_hint
+        logger.warning('Template variable warning: %s', hint)
+
+    class LoggingUndefined(base):
+
+        def _fail_with_undefined_error(self, *args, **kwargs):
+            try:
+                return base._fail_with_undefined_error(self, *args, **kwargs)
+            except self._undefined_exception as e:
+                logger.error('Template variable error: %s', str(e))
+                raise e
+
+        def __str__(self):
+            rv = base.__str__(self)
+            _log_message(self)
+            return rv
+
+        def __iter__(self):
+            rv = base.__iter__(self)
+            _log_message(self)
+            return rv
+
+        if PY2:
+            def __nonzero__(self):
+                rv = base.__nonzero__(self)
+                _log_message(self)
+                return rv
+
+            def __unicode__(self):
+                rv = base.__unicode__(self)
+                _log_message(self)
+                return rv
+        else:
+            def __bool__(self):
+                rv = base.__bool__(self)
+                _log_message(self)
+                return rv
+
+    return LoggingUndefined
+
+
+@implements_to_string
+class DebugUndefined(Undefined):
+    """An undefined that returns the debug info when printed.
+
+    >>> foo = DebugUndefined(name='foo')
+    >>> str(foo)
+    '{{ foo }}'
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+    __slots__ = ()
+
+    def __str__(self):
+        if self._undefined_hint is None:
+            if self._undefined_obj is missing:
+                return u'{{ %s }}' % self._undefined_name
+            return '{{ no such element: %s[%r] }}' % (
+                object_type_repr(self._undefined_obj),
+                self._undefined_name
+            )
+        return u'{{ undefined value printed: %s }}' % self._undefined_hint
+
+
+@implements_to_string
+class StrictUndefined(Undefined):
+    """An undefined that barks on print and iteration as well as boolean
+    tests and all kinds of comparisons.  In other words: you can do nothing
+    with it except checking if it's defined using the `defined` test.
+
+    >>> foo = StrictUndefined(name='foo')
+    >>> str(foo)
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> not foo
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+    __slots__ = ()
+    __iter__ = __str__ = __len__ = __nonzero__ = __eq__ = \
+        __ne__ = __bool__ = __hash__ = \
+        Undefined._fail_with_undefined_error
+
+
+# remove remaining slots attributes, after the metaclass did the magic they
+# are unneeded and irritating as they contain wrong data for the subclasses.
+del Undefined.__slots__, DebugUndefined.__slots__, StrictUndefined.__slots__
diff --git a/python/jinja2/sandbox.py b/python/jinja2/sandbox.py
new file mode 100644
index 0000000..752e812
--- /dev/null
+++ b/python/jinja2/sandbox.py
@@ -0,0 +1,486 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.sandbox
+    ~~~~~~~~~~~~~~
+
+    Adds a sandbox layer to Jinja as it was the default behavior in the old
+    Jinja 1 releases.  This sandbox is slightly different from Jinja 1 as the
+    default behavior is easier to use.
+
+    The behavior can be changed by subclassing the environment.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+import types
+import operator
+from collections import Mapping
+from jinja2.environment import Environment
+from jinja2.exceptions import SecurityError
+from jinja2._compat import string_types, PY2
+from jinja2.utils import Markup
+
+from markupsafe import EscapeFormatter
+from string import Formatter
+
+
+#: maximum number of items a range may produce
+MAX_RANGE = 100000
+
+#: attributes of function objects that are considered unsafe.
+if PY2:
+    UNSAFE_FUNCTION_ATTRIBUTES = set(['func_closure', 'func_code', 'func_dict',
+                                      'func_defaults', 'func_globals'])
+else:
+    # On versions > python 2 the special attributes on functions are gone,
+    # but they remain on methods and generators for whatever reason.
+    UNSAFE_FUNCTION_ATTRIBUTES = set()
+
+
+#: unsafe method attributes.  function attributes are unsafe for methods too
+UNSAFE_METHOD_ATTRIBUTES = set(['im_class', 'im_func', 'im_self'])
+
+#: unsafe generator attirbutes.
+UNSAFE_GENERATOR_ATTRIBUTES = set(['gi_frame', 'gi_code'])
+
+#: unsafe attributes on coroutines
+UNSAFE_COROUTINE_ATTRIBUTES = set(['cr_frame', 'cr_code'])
+
+#: unsafe attributes on async generators
+UNSAFE_ASYNC_GENERATOR_ATTRIBUTES = set(['ag_code', 'ag_frame'])
+
+import warnings
+
+# make sure we don't warn in python 2.6 about stuff we don't care about
+warnings.filterwarnings('ignore', 'the sets module', DeprecationWarning,
+                        module='jinja2.sandbox')
+
+from collections import deque
+
+_mutable_set_types = (set,)
+_mutable_mapping_types = (dict,)
+_mutable_sequence_types = (list,)
+
+
+# on python 2.x we can register the user collection types
+try:
+    from UserDict import UserDict, DictMixin
+    from UserList import UserList
+    _mutable_mapping_types += (UserDict, DictMixin)
+    _mutable_set_types += (UserList,)
+except ImportError:
+    pass
+
+# if sets is still available, register the mutable set from there as well
+try:
+    from sets import Set
+    _mutable_set_types += (Set,)
+except ImportError:
+    pass
+
+#: register Python 2.6 abstract base classes
+from collections import MutableSet, MutableMapping, MutableSequence
+_mutable_set_types += (MutableSet,)
+_mutable_mapping_types += (MutableMapping,)
+_mutable_sequence_types += (MutableSequence,)
+
+
+_mutable_spec = (
+    (_mutable_set_types, frozenset([
+        'add', 'clear', 'difference_update', 'discard', 'pop', 'remove',
+        'symmetric_difference_update', 'update'
+    ])),
+    (_mutable_mapping_types, frozenset([
+        'clear', 'pop', 'popitem', 'setdefault', 'update'
+    ])),
+    (_mutable_sequence_types, frozenset([
+        'append', 'reverse', 'insert', 'sort', 'extend', 'remove'
+    ])),
+    (deque, frozenset([
+        'append', 'appendleft', 'clear', 'extend', 'extendleft', 'pop',
+        'popleft', 'remove', 'rotate'
+    ]))
+)
+
+
+class _MagicFormatMapping(Mapping):
+    """This class implements a dummy wrapper to fix a bug in the Python
+    standard library for string formatting.
+
+    See https://bugs.python.org/issue13598 for information about why
+    this is necessary.
+    """
+
+    def __init__(self, args, kwargs):
+        self._args = args
+        self._kwargs = kwargs
+        self._last_index = 0
+
+    def __getitem__(self, key):
+        if key == '':
+            idx = self._last_index
+            self._last_index += 1
+            try:
+                return self._args[idx]
+            except LookupError:
+                pass
+            key = str(idx)
+        return self._kwargs[key]
+
+    def __iter__(self):
+        return iter(self._kwargs)
+
+    def __len__(self):
+        return len(self._kwargs)
+
+
+def inspect_format_method(callable):
+    if not isinstance(callable, (types.MethodType,
+                                 types.BuiltinMethodType)) or \
+       callable.__name__ not in ('format', 'format_map'):
+        return None
+    obj = callable.__self__
+    if isinstance(obj, string_types):
+        return obj
+
+
+def safe_range(*args):
+    """A range that can't generate ranges with a length of more than
+    MAX_RANGE items.
+    """
+    rng = range(*args)
+    if len(rng) > MAX_RANGE:
+        raise OverflowError('range too big, maximum size for range is %d' %
+                            MAX_RANGE)
+    return rng
+
+
+def unsafe(f):
+    """Marks a function or method as unsafe.
+
+    ::
+
+        @unsafe
+        def delete(self):
+            pass
+    """
+    f.unsafe_callable = True
+    return f
+
+
+def is_internal_attribute(obj, attr):
+    """Test if the attribute given is an internal python attribute.  For
+    example this function returns `True` for the `func_code` attribute of
+    python objects.  This is useful if the environment method
+    :meth:`~SandboxedEnvironment.is_safe_attribute` is overridden.
+
+    >>> from jinja2.sandbox import is_internal_attribute
+    >>> is_internal_attribute(str, "mro")
+    True
+    >>> is_internal_attribute(str, "upper")
+    False
+    """
+    if isinstance(obj, types.FunctionType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES:
+            return True
+    elif isinstance(obj, types.MethodType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES or \
+           attr in UNSAFE_METHOD_ATTRIBUTES:
+            return True
+    elif isinstance(obj, type):
+        if attr == 'mro':
+            return True
+    elif isinstance(obj, (types.CodeType, types.TracebackType, types.FrameType)):
+        return True
+    elif isinstance(obj, types.GeneratorType):
+        if attr in UNSAFE_GENERATOR_ATTRIBUTES:
+            return True
+    elif hasattr(types, 'CoroutineType') and isinstance(obj, types.CoroutineType):
+        if attr in UNSAFE_COROUTINE_ATTRIBUTES:
+            return True
+    elif hasattr(types, 'AsyncGeneratorType') and isinstance(obj, types.AsyncGeneratorType):
+        if attr in UNSAFE_ASYNC_GENERATOR_ATTRIBUTES:
+            return True
+    return attr.startswith('__')
+
+
+def modifies_known_mutable(obj, attr):
+    """This function checks if an attribute on a builtin mutable object
+    (list, dict, set or deque) would modify it if called.  It also supports
+    the "user"-versions of the objects (`sets.Set`, `UserDict.*` etc.) and
+    with Python 2.6 onwards the abstract base classes `MutableSet`,
+    `MutableMapping`, and `MutableSequence`.
+
+    >>> modifies_known_mutable({}, "clear")
+    True
+    >>> modifies_known_mutable({}, "keys")
+    False
+    >>> modifies_known_mutable([], "append")
+    True
+    >>> modifies_known_mutable([], "index")
+    False
+
+    If called with an unsupported object (such as unicode) `False` is
+    returned.
+
+    >>> modifies_known_mutable("foo", "upper")
+    False
+    """
+    for typespec, unsafe in _mutable_spec:
+        if isinstance(obj, typespec):
+            return attr in unsafe
+    return False
+
+
+class SandboxedEnvironment(Environment):
+    """The sandboxed environment.  It works like the regular environment but
+    tells the compiler to generate sandboxed code.  Additionally subclasses of
+    this environment may override the methods that tell the runtime what
+    attributes or functions are safe to access.
+
+    If the template tries to access insecure code a :exc:`SecurityError` is
+    raised.  However also other exceptions may occur during the rendering so
+    the caller has to ensure that all exceptions are caught.
+    """
+    sandboxed = True
+
+    #: default callback table for the binary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`binop_table`
+    default_binop_table = {
+        '+':        operator.add,
+        '-':        operator.sub,
+        '*':        operator.mul,
+        '/':        operator.truediv,
+        '//':       operator.floordiv,
+        '**':       operator.pow,
+        '%':        operator.mod
+    }
+
+    #: default callback table for the unary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`unop_table`
+    default_unop_table = {
+        '+':        operator.pos,
+        '-':        operator.neg
+    }
+
+    #: a set of binary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_binop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`binop_table`.
+    #:
+    #: The following binary operators are interceptable:
+    #: ``//``, ``%``, ``+``, ``*``, ``-``, ``/``, and ``**``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_binops = frozenset()
+
+    #: a set of unary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_unop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`unop_table`.
+    #:
+    #: The following unary operators are interceptable: ``+``, ``-``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_unops = frozenset()
+
+    def intercept_unop(self, operator):
+        """Called during template compilation with the name of a unary
+        operator to check if it should be intercepted at runtime.  If this
+        method returns `True`, :meth:`call_unop` is excuted for this unary
+        operator.  The default implementation of :meth:`call_unop` will use
+        the :attr:`unop_table` dictionary to perform the operator with the
+        same logic as the builtin one.
+
+        The following unary operators are interceptable: ``+`` and ``-``
+
+        Intercepted calls are always slower than the native operator call,
+        so make sure only to intercept the ones you are interested in.
+
+        .. versionadded:: 2.6
+        """
+        return False
+
+
+    def __init__(self, *args, **kwargs):
+        Environment.__init__(self, *args, **kwargs)
+        self.globals['range'] = safe_range
+        self.binop_table = self.default_binop_table.copy()
+        self.unop_table = self.default_unop_table.copy()
+
+    def is_safe_attribute(self, obj, attr, value):
+        """The sandboxed environment will call this method to check if the
+        attribute of an object is safe to access.  Per default all attributes
+        starting with an underscore are considered private as well as the
+        special attributes of internal python objects as returned by the
+        :func:`is_internal_attribute` function.
+        """
+        return not (attr.startswith('_') or is_internal_attribute(obj, attr))
+
+    def is_safe_callable(self, obj):
+        """Check if an object is safely callable.  Per default a function is
+        considered safe unless the `unsafe_callable` attribute exists and is
+        True.  Override this method to alter the behavior, but this won't
+        affect the `unsafe` decorator from this module.
+        """
+        return not (getattr(obj, 'unsafe_callable', False) or
+                    getattr(obj, 'alters_data', False))
+
+    def call_binop(self, context, operator, left, right):
+        """For intercepted binary operator calls (:meth:`intercepted_binops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.binop_table[operator](left, right)
+
+    def call_unop(self, context, operator, arg):
+        """For intercepted unary operator calls (:meth:`intercepted_unops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.unop_table[operator](arg)
+
+    def getitem(self, obj, argument):
+        """Subscribe an object from sandboxed code."""
+        try:
+            return obj[argument]
+        except (TypeError, LookupError):
+            if isinstance(argument, string_types):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        value = getattr(obj, attr)
+                    except AttributeError:
+                        pass
+                    else:
+                        if self.is_safe_attribute(obj, argument, value):
+                            return value
+                        return self.unsafe_undefined(obj, argument)
+        return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj, attribute):
+        """Subscribe an object from sandboxed code and prefer the
+        attribute.  The attribute passed *must* be a bytestring.
+        """
+        try:
+            value = getattr(obj, attribute)
+        except AttributeError:
+            try:
+                return obj[attribute]
+            except (TypeError, LookupError):
+                pass
+        else:
+            if self.is_safe_attribute(obj, attribute, value):
+                return value
+            return self.unsafe_undefined(obj, attribute)
+        return self.undefined(obj=obj, name=attribute)
+
+    def unsafe_undefined(self, obj, attribute):
+        """Return an undefined object for unsafe attributes."""
+        return self.undefined('access to attribute %r of %r '
+                              'object is unsafe.' % (
+            attribute,
+            obj.__class__.__name__
+        ), name=attribute, obj=obj, exc=SecurityError)
+
+    def format_string(self, s, args, kwargs, format_func=None):
+        """If a format call is detected, then this is routed through this
+        method so that our safety sandbox can be used for it.
+        """
+        if isinstance(s, Markup):
+            formatter = SandboxedEscapeFormatter(self, s.escape)
+        else:
+            formatter = SandboxedFormatter(self)
+
+        if format_func is not None and format_func.__name__ == 'format_map':
+            if len(args) != 1 or kwargs:
+                raise TypeError(
+                    'format_map() takes exactly one argument %d given'
+                    % (len(args) + (kwargs is not None))
+                )
+
+            kwargs = args[0]
+            args = None
+
+        kwargs = _MagicFormatMapping(args, kwargs)
+        rv = formatter.vformat(s, args, kwargs)
+        return type(s)(rv)
+
+    def call(__self, __context, __obj, *args, **kwargs):
+        """Call an object from sandboxed code."""
+        fmt = inspect_format_method(__obj)
+        if fmt is not None:
+            return __self.format_string(fmt, args, kwargs, __obj)
+
+        # the double prefixes are to avoid double keyword argument
+        # errors when proxying the call.
+        if not __self.is_safe_callable(__obj):
+            raise SecurityError('%r is not safely callable' % (__obj,))
+        return __context.call(__obj, *args, **kwargs)
+
+
+class ImmutableSandboxedEnvironment(SandboxedEnvironment):
+    """Works exactly like the regular `SandboxedEnvironment` but does not
+    permit modifications on the builtin mutable objects `list`, `set`, and
+    `dict` by using the :func:`modifies_known_mutable` function.
+    """
+
+    def is_safe_attribute(self, obj, attr, value):
+        if not SandboxedEnvironment.is_safe_attribute(self, obj, attr, value):
+            return False
+        return not modifies_known_mutable(obj, attr)
+
+
+# This really is not a public API apparenlty.
+try:
+    from _string import formatter_field_name_split
+except ImportError:
+    def formatter_field_name_split(field_name):
+        return field_name._formatter_field_name_split()
+
+
+class SandboxedFormatterMixin(object):
+
+    def __init__(self, env):
+        self._env = env
+
+    def get_field(self, field_name, args, kwargs):
+        first, rest = formatter_field_name_split(field_name)
+        obj = self.get_value(first, args, kwargs)
+        for is_attr, i in rest:
+            if is_attr:
+                obj = self._env.getattr(obj, i)
+            else:
+                obj = self._env.getitem(obj, i)
+        return obj, first
+
+class SandboxedFormatter(SandboxedFormatterMixin, Formatter):
+
+    def __init__(self, env):
+        SandboxedFormatterMixin.__init__(self, env)
+        Formatter.__init__(self)
+
+class SandboxedEscapeFormatter(SandboxedFormatterMixin, EscapeFormatter):
+
+    def __init__(self, env, escape):
+        SandboxedFormatterMixin.__init__(self, env)
+        EscapeFormatter.__init__(self, escape)
diff --git a/python/jinja2/tests.py b/python/jinja2/tests.py
new file mode 100644
index 0000000..0adc3d4
--- /dev/null
+++ b/python/jinja2/tests.py
@@ -0,0 +1,175 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.tests
+    ~~~~~~~~~~~~
+
+    Jinja test functions. Used with the "is" operator.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import operator
+import re
+from collections import Mapping
+from jinja2.runtime import Undefined
+from jinja2._compat import text_type, string_types, integer_types
+import decimal
+
+number_re = re.compile(r'^-?\d+(\.\d+)?$')
+regex_type = type(number_re)
+
+
+test_callable = callable
+
+
+def test_odd(value):
+    """Return true if the variable is odd."""
+    return value % 2 == 1
+
+
+def test_even(value):
+    """Return true if the variable is even."""
+    return value % 2 == 0
+
+
+def test_divisibleby(value, num):
+    """Check if a variable is divisible by a number."""
+    return value % num == 0
+
+
+def test_defined(value):
+    """Return true if the variable is defined:
+
+    .. sourcecode:: jinja
+
+        {% if variable is defined %}
+            value of variable: {{ variable }}
+        {% else %}
+            variable is not defined
+        {% endif %}
+
+    See the :func:`default` filter for a simple way to set undefined
+    variables.
+    """
+    return not isinstance(value, Undefined)
+
+
+def test_undefined(value):
+    """Like :func:`defined` but the other way round."""
+    return isinstance(value, Undefined)
+
+
+def test_none(value):
+    """Return true if the variable is none."""
+    return value is None
+
+
+def test_lower(value):
+    """Return true if the variable is lowercased."""
+    return text_type(value).islower()
+
+
+def test_upper(value):
+    """Return true if the variable is uppercased."""
+    return text_type(value).isupper()
+
+
+def test_string(value):
+    """Return true if the object is a string."""
+    return isinstance(value, string_types)
+
+
+def test_mapping(value):
+    """Return true if the object is a mapping (dict etc.).
+
+    .. versionadded:: 2.6
+    """
+    return isinstance(value, Mapping)
+
+
+def test_number(value):
+    """Return true if the variable is a number."""
+    return isinstance(value, integer_types + (float, complex, decimal.Decimal))
+
+
+def test_sequence(value):
+    """Return true if the variable is a sequence. Sequences are variables
+    that are iterable.
+    """
+    try:
+        len(value)
+        value.__getitem__
+    except:
+        return False
+    return True
+
+
+def test_sameas(value, other):
+    """Check if an object points to the same memory address than another
+    object:
+
+    .. sourcecode:: jinja
+
+        {% if foo.attribute is sameas false %}
+            the foo attribute really is the `False` singleton
+        {% endif %}
+    """
+    return value is other
+
+
+def test_iterable(value):
+    """Check if it's possible to iterate over an object."""
+    try:
+        iter(value)
+    except TypeError:
+        return False
+    return True
+
+
+def test_escaped(value):
+    """Check if the value is escaped."""
+    return hasattr(value, '__html__')
+
+
+def test_in(value, seq):
+    """Check if value is in seq.
+
+    .. versionadded:: 2.10
+    """
+    return value in seq
+
+
+TESTS = {
+    'odd':              test_odd,
+    'even':             test_even,
+    'divisibleby':      test_divisibleby,
+    'defined':          test_defined,
+    'undefined':        test_undefined,
+    'none':             test_none,
+    'lower':            test_lower,
+    'upper':            test_upper,
+    'string':           test_string,
+    'mapping':          test_mapping,
+    'number':           test_number,
+    'sequence':         test_sequence,
+    'iterable':         test_iterable,
+    'callable':         test_callable,
+    'sameas':           test_sameas,
+    'escaped':          test_escaped,
+    'in':               test_in,
+    '==':               operator.eq,
+    'eq':               operator.eq,
+    'equalto':          operator.eq,
+    '!=':               operator.ne,
+    'ne':               operator.ne,
+    '>':                operator.gt,
+    'gt':               operator.gt,
+    'greaterthan':      operator.gt,
+    'ge':               operator.ge,
+    '>=':               operator.ge,
+    '<':                operator.lt,
+    'lt':               operator.lt,
+    'lessthan':         operator.lt,
+    '<=':               operator.le,
+    'le':               operator.le,
+}
diff --git a/python/jinja2/utils.py b/python/jinja2/utils.py
new file mode 100644
index 0000000..502a311
--- /dev/null
+++ b/python/jinja2/utils.py
@@ -0,0 +1,647 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.utils
+    ~~~~~~~~~~~~
+
+    Utility functions.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD, see LICENSE for more details.
+"""
+import re
+import json
+import errno
+from collections import deque
+from threading import Lock
+from jinja2._compat import text_type, string_types, implements_iterator, \
+     url_quote
+
+
+_word_split_re = re.compile(r'(\s+)')
+_punctuation_re = re.compile(
+    '^(?P<lead>(?:%s)*)(?P<middle>.*?)(?P<trail>(?:%s)*)$' % (
+        '|'.join(map(re.escape, ('(', '<', '&lt;'))),
+        '|'.join(map(re.escape, ('.', ',', ')', '>', '\n', '&gt;')))
+    )
+)
+_simple_email_re = re.compile(r'^\S+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+$')
+_striptags_re = re.compile(r'(<!--.*?-->|<[^>]*>)')
+_entity_re = re.compile(r'&([^;]+);')
+_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
+_digits = '0123456789'
+
+# special singleton representing missing values for the runtime
+missing = type('MissingType', (), {'__repr__': lambda x: 'missing'})()
+
+# internal code
+internal_code = set()
+
+concat = u''.join
+
+_slash_escape = '\\/' not in json.dumps('/')
+
+
+def contextfunction(f):
+    """This decorator can be used to mark a function or method context callable.
+    A context callable is passed the active :class:`Context` as first argument when
+    called from the template.  This is useful if a function wants to get access
+    to the context or functions provided on the context object.  For example
+    a function that returns a sorted list of template variables the current
+    template exports could look like this::
+
+        @contextfunction
+        def get_exported_names(context):
+            return sorted(context.exported_vars)
+    """
+    f.contextfunction = True
+    return f
+
+
+def evalcontextfunction(f):
+    """This decorator can be used to mark a function or method as an eval
+    context callable.  This is similar to the :func:`contextfunction`
+    but instead of passing the context, an evaluation context object is
+    passed.  For more information about the eval context, see
+    :ref:`eval-context`.
+
+    .. versionadded:: 2.4
+    """
+    f.evalcontextfunction = True
+    return f
+
+
+def environmentfunction(f):
+    """This decorator can be used to mark a function or method as environment
+    callable.  This decorator works exactly like the :func:`contextfunction`
+    decorator just that the first argument is the active :class:`Environment`
+    and not context.
+    """
+    f.environmentfunction = True
+    return f
+
+
+def internalcode(f):
+    """Marks the function as internally used"""
+    internal_code.add(f.__code__)
+    return f
+
+
+def is_undefined(obj):
+    """Check if the object passed is undefined.  This does nothing more than
+    performing an instance check against :class:`Undefined` but looks nicer.
+    This can be used for custom filters or tests that want to react to
+    undefined variables.  For example a custom default filter can look like
+    this::
+
+        def default(var, default=''):
+            if is_undefined(var):
+                return default
+            return var
+    """
+    from jinja2.runtime import Undefined
+    return isinstance(obj, Undefined)
+
+
+def consume(iterable):
+    """Consumes an iterable without doing anything with it."""
+    for event in iterable:
+        pass
+
+
+def clear_caches():
+    """Jinja2 keeps internal caches for environments and lexers.  These are
+    used so that Jinja2 doesn't have to recreate environments and lexers all
+    the time.  Normally you don't have to care about that but if you are
+    measuring memory consumption you may want to clean the caches.
+    """
+    from jinja2.environment import _spontaneous_environments
+    from jinja2.lexer import _lexer_cache
+    _spontaneous_environments.clear()
+    _lexer_cache.clear()
+
+
+def import_string(import_name, silent=False):
+    """Imports an object based on a string.  This is useful if you want to
+    use import paths as endpoints or something similar.  An import path can
+    be specified either in dotted notation (``xml.sax.saxutils.escape``)
+    or with a colon as object delimiter (``xml.sax.saxutils:escape``).
+
+    If the `silent` is True the return value will be `None` if the import
+    fails.
+
+    :return: imported object
+    """
+    try:
+        if ':' in import_name:
+            module, obj = import_name.split(':', 1)
+        elif '.' in import_name:
+            items = import_name.split('.')
+            module = '.'.join(items[:-1])
+            obj = items[-1]
+        else:
+            return __import__(import_name)
+        return getattr(__import__(module, None, None, [obj]), obj)
+    except (ImportError, AttributeError):
+        if not silent:
+            raise
+
+
+def open_if_exists(filename, mode='rb'):
+    """Returns a file descriptor for the filename if that file exists,
+    otherwise `None`.
+    """
+    try:
+        return open(filename, mode)
+    except IOError as e:
+        if e.errno not in (errno.ENOENT, errno.EISDIR, errno.EINVAL):
+            raise
+
+
+def object_type_repr(obj):
+    """Returns the name of the object's type.  For some recognized
+    singletons the name of the object is returned instead. (For
+    example for `None` and `Ellipsis`).
+    """
+    if obj is None:
+        return 'None'
+    elif obj is Ellipsis:
+        return 'Ellipsis'
+    # __builtin__ in 2.x, builtins in 3.x
+    if obj.__class__.__module__ in ('__builtin__', 'builtins'):
+        name = obj.__class__.__name__
+    else:
+        name = obj.__class__.__module__ + '.' + obj.__class__.__name__
+    return '%s object' % name
+
+
+def pformat(obj, verbose=False):
+    """Prettyprint an object.  Either use the `pretty` library or the
+    builtin `pprint`.
+    """
+    try:
+        from pretty import pretty
+        return pretty(obj, verbose=verbose)
+    except ImportError:
+        from pprint import pformat
+        return pformat(obj)
+
+
+def urlize(text, trim_url_limit=None, rel=None, target=None):
+    """Converts any URLs in text into clickable links. Works on http://,
+    https:// and www. links. Links can have trailing punctuation (periods,
+    commas, close-parens) and leading punctuation (opening parens) and
+    it'll still do the right thing.
+
+    If trim_url_limit is not None, the URLs in link text will be limited
+    to trim_url_limit characters.
+
+    If nofollow is True, the URLs in link text will get a rel="nofollow"
+    attribute.
+
+    If target is not None, a target attribute will be added to the link.
+    """
+    trim_url = lambda x, limit=trim_url_limit: limit is not None \
+                         and (x[:limit] + (len(x) >=limit and '...'
+                         or '')) or x
+    words = _word_split_re.split(text_type(escape(text)))
+    rel_attr = rel and ' rel="%s"' % text_type(escape(rel)) or ''
+    target_attr = target and ' target="%s"' % escape(target) or ''
+
+    for i, word in enumerate(words):
+        match = _punctuation_re.match(word)
+        if match:
+            lead, middle, trail = match.groups()
+            if middle.startswith('www.') or (
+                '@' not in middle and
+                not middle.startswith('http://') and
+                not middle.startswith('https://') and
+                len(middle) > 0 and
+                middle[0] in _letters + _digits and (
+                    middle.endswith('.org') or
+                    middle.endswith('.net') or
+                    middle.endswith('.com')
+                )):
+                middle = '<a href="http://%s"%s%s>%s</a>' % (middle,
+                    rel_attr, target_attr, trim_url(middle))
+            if middle.startswith('http://') or \
+               middle.startswith('https://'):
+                middle = '<a href="%s"%s%s>%s</a>' % (middle,
+                    rel_attr, target_attr, trim_url(middle))
+            if '@' in middle and not middle.startswith('www.') and \
+               not ':' in middle and _simple_email_re.match(middle):
+                middle = '<a href="mailto:%s">%s</a>' % (middle, middle)
+            if lead + middle + trail != word:
+                words[i] = lead + middle + trail
+    return u''.join(words)
+
+
+def generate_lorem_ipsum(n=5, html=True, min=20, max=100):
+    """Generate some lorem ipsum for the template."""
+    from jinja2.constants import LOREM_IPSUM_WORDS
+    from random import choice, randrange
+    words = LOREM_IPSUM_WORDS.split()
+    result = []
+
+    for _ in range(n):
+        next_capitalized = True
+        last_comma = last_fullstop = 0
+        word = None
+        last = None
+        p = []
+
+        # each paragraph contains out of 20 to 100 words.
+        for idx, _ in enumerate(range(randrange(min, max))):
+            while True:
+                word = choice(words)
+                if word != last:
+                    last = word
+                    break
+            if next_capitalized:
+                word = word.capitalize()
+                next_capitalized = False
+            # add commas
+            if idx - randrange(3, 8) > last_comma:
+                last_comma = idx
+                last_fullstop += 2
+                word += ','
+            # add end of sentences
+            if idx - randrange(10, 20) > last_fullstop:
+                last_comma = last_fullstop = idx
+                word += '.'
+                next_capitalized = True
+            p.append(word)
+
+        # ensure that the paragraph ends with a dot.
+        p = u' '.join(p)
+        if p.endswith(','):
+            p = p[:-1] + '.'
+        elif not p.endswith('.'):
+            p += '.'
+        result.append(p)
+
+    if not html:
+        return u'\n\n'.join(result)
+    return Markup(u'\n'.join(u'<p>%s</p>' % escape(x) for x in result))
+
+
+def unicode_urlencode(obj, charset='utf-8', for_qs=False):
+    """URL escapes a single bytestring or unicode string with the
+    given charset if applicable to URL safe quoting under all rules
+    that need to be considered under all supported Python versions.
+
+    If non strings are provided they are converted to their unicode
+    representation first.
+    """
+    if not isinstance(obj, string_types):
+        obj = text_type(obj)
+    if isinstance(obj, text_type):
+        obj = obj.encode(charset)
+    safe = not for_qs and b'/' or b''
+    rv = text_type(url_quote(obj, safe))
+    if for_qs:
+        rv = rv.replace('%20', '+')
+    return rv
+
+
+class LRUCache(object):
+    """A simple LRU Cache implementation."""
+
+    # this is fast for small capacities (something below 1000) but doesn't
+    # scale.  But as long as it's only used as storage for templates this
+    # won't do any harm.
+
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self._mapping = {}
+        self._queue = deque()
+        self._postinit()
+
+    def _postinit(self):
+        # alias all queue methods for faster lookup
+        self._popleft = self._queue.popleft
+        self._pop = self._queue.pop
+        self._remove = self._queue.remove
+        self._wlock = Lock()
+        self._append = self._queue.append
+
+    def __getstate__(self):
+        return {
+            'capacity':     self.capacity,
+            '_mapping':     self._mapping,
+            '_queue':       self._queue
+        }
+
+    def __setstate__(self, d):
+        self.__dict__.update(d)
+        self._postinit()
+
+    def __getnewargs__(self):
+        return (self.capacity,)
+
+    def copy(self):
+        """Return a shallow copy of the instance."""
+        rv = self.__class__(self.capacity)
+        rv._mapping.update(self._mapping)
+        rv._queue = deque(self._queue)
+        return rv
+
+    def get(self, key, default=None):
+        """Return an item from the cache dict or `default`"""
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def setdefault(self, key, default=None):
+        """Set `default` if the key is not in the cache otherwise
+        leave unchanged. Return the value of this key.
+        """
+        self._wlock.acquire()
+        try:
+            try:
+                return self[key]
+            except KeyError:
+                self[key] = default
+                return default
+        finally:
+            self._wlock.release()
+
+    def clear(self):
+        """Clear the cache."""
+        self._wlock.acquire()
+        try:
+            self._mapping.clear()
+            self._queue.clear()
+        finally:
+            self._wlock.release()
+
+    def __contains__(self, key):
+        """Check if a key exists in this cache."""
+        return key in self._mapping
+
+    def __len__(self):
+        """Return the current size of the cache."""
+        return len(self._mapping)
+
+    def __repr__(self):
+        return '<%s %r>' % (
+            self.__class__.__name__,
+            self._mapping
+        )
+
+    def __getitem__(self, key):
+        """Get an item from the cache. Moves the item up so that it has the
+        highest priority then.
+
+        Raise a `KeyError` if it does not exist.
+        """
+        self._wlock.acquire()
+        try:
+            rv = self._mapping[key]
+            if self._queue[-1] != key:
+                try:
+                    self._remove(key)
+                except ValueError:
+                    # if something removed the key from the container
+                    # when we read, ignore the ValueError that we would
+                    # get otherwise.
+                    pass
+                self._append(key)
+            return rv
+        finally:
+            self._wlock.release()
+
+    def __setitem__(self, key, value):
+        """Sets the value for an item. Moves the item up so that it
+        has the highest priority then.
+        """
+        self._wlock.acquire()
+        try:
+            if key in self._mapping:
+                self._remove(key)
+            elif len(self._mapping) == self.capacity:
+                del self._mapping[self._popleft()]
+            self._append(key)
+            self._mapping[key] = value
+        finally:
+            self._wlock.release()
+
+    def __delitem__(self, key):
+        """Remove an item from the cache dict.
+        Raise a `KeyError` if it does not exist.
+        """
+        self._wlock.acquire()
+        try:
+            del self._mapping[key]
+            try:
+                self._remove(key)
+            except ValueError:
+                # __getitem__ is not locked, it might happen
+                pass
+        finally:
+            self._wlock.release()
+
+    def items(self):
+        """Return a list of items."""
+        result = [(key, self._mapping[key]) for key in list(self._queue)]
+        result.reverse()
+        return result
+
+    def iteritems(self):
+        """Iterate over all items."""
+        return iter(self.items())
+
+    def values(self):
+        """Return a list of all values."""
+        return [x[1] for x in self.items()]
+
+    def itervalue(self):
+        """Iterate over all values."""
+        return iter(self.values())
+
+    def keys(self):
+        """Return a list of all keys ordered by most recent usage."""
+        return list(self)
+
+    def iterkeys(self):
+        """Iterate over all keys in the cache dict, ordered by
+        the most recent usage.
+        """
+        return reversed(tuple(self._queue))
+
+    __iter__ = iterkeys
+
+    def __reversed__(self):
+        """Iterate over the values in the cache dict, oldest items
+        coming first.
+        """
+        return iter(tuple(self._queue))
+
+    __copy__ = copy
+
+
+# register the LRU cache as mutable mapping if possible
+try:
+    from collections import MutableMapping
+    MutableMapping.register(LRUCache)
+except ImportError:
+    pass
+
+
+def select_autoescape(enabled_extensions=('html', 'htm', 'xml'),
+                      disabled_extensions=(),
+                      default_for_string=True,
+                      default=False):
+    """Intelligently sets the initial value of autoescaping based on the
+    filename of the template.  This is the recommended way to configure
+    autoescaping if you do not want to write a custom function yourself.
+
+    If you want to enable it for all templates created from strings or
+    for all templates with `.html` and `.xml` extensions::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            enabled_extensions=('html', 'xml'),
+            default_for_string=True,
+        ))
+
+    Example configuration to turn it on at all times except if the template
+    ends with `.txt`::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            disabled_extensions=('txt',),
+            default_for_string=True,
+            default=True,
+        ))
+
+    The `enabled_extensions` is an iterable of all the extensions that
+    autoescaping should be enabled for.  Likewise `disabled_extensions` is
+    a list of all templates it should be disabled for.  If a template is
+    loaded from a string then the default from `default_for_string` is used.
+    If nothing matches then the initial value of autoescaping is set to the
+    value of `default`.
+
+    For security reasons this function operates case insensitive.
+
+    .. versionadded:: 2.9
+    """
+    enabled_patterns = tuple('.' + x.lstrip('.').lower()
+                             for x in enabled_extensions)
+    disabled_patterns = tuple('.' + x.lstrip('.').lower()
+                              for x in disabled_extensions)
+    def autoescape(template_name):
+        if template_name is None:
+            return default_for_string
+        template_name = template_name.lower()
+        if template_name.endswith(enabled_patterns):
+            return True
+        if template_name.endswith(disabled_patterns):
+            return False
+        return default
+    return autoescape
+
+
+def htmlsafe_json_dumps(obj, dumper=None, **kwargs):
+    """Works exactly like :func:`dumps` but is safe for use in ``<script>``
+    tags.  It accepts the same arguments and returns a JSON string.  Note that
+    this is available in templates through the ``|tojson`` filter which will
+    also mark the result as safe.  Due to how this function escapes certain
+    characters this is safe even if used outside of ``<script>`` tags.
+
+    The following characters are escaped in strings:
+
+    -   ``<``
+    -   ``>``
+    -   ``&``
+    -   ``'``
+
+    This makes it safe to embed such strings in any place in HTML with the
+    notable exception of double quoted attributes.  In that case single
+    quote your attributes or HTML escape it in addition.
+    """
+    if dumper is None:
+        dumper = json.dumps
+    rv = dumper(obj, **kwargs) \
+        .replace(u'<', u'\\u003c') \
+        .replace(u'>', u'\\u003e') \
+        .replace(u'&', u'\\u0026') \
+        .replace(u"'", u'\\u0027')
+    return Markup(rv)
+
+
+@implements_iterator
+class Cycler(object):
+    """A cycle helper for templates."""
+
+    def __init__(self, *items):
+        if not items:
+            raise RuntimeError('at least one item has to be provided')
+        self.items = items
+        self.reset()
+
+    def reset(self):
+        """Resets the cycle."""
+        self.pos = 0
+
+    @property
+    def current(self):
+        """Returns the current item."""
+        return self.items[self.pos]
+
+    def next(self):
+        """Goes one item ahead and returns it."""
+        rv = self.current
+        self.pos = (self.pos + 1) % len(self.items)
+        return rv
+
+    __next__ = next
+
+
+class Joiner(object):
+    """A joining helper for templates."""
+
+    def __init__(self, sep=u', '):
+        self.sep = sep
+        self.used = False
+
+    def __call__(self):
+        if not self.used:
+            self.used = True
+            return u''
+        return self.sep
+
+
+class Namespace(object):
+    """A namespace object that can hold arbitrary attributes.  It may be
+    initialized from a dictionary or with keyword argments."""
+
+    def __init__(*args, **kwargs):
+        self, args = args[0], args[1:]
+        self.__attrs = dict(*args, **kwargs)
+
+    def __getattribute__(self, name):
+        if name == '_Namespace__attrs':
+            return object.__getattribute__(self, name)
+        try:
+            return self.__attrs[name]
+        except KeyError:
+            raise AttributeError(name)
+
+    def __setitem__(self, name, value):
+        self.__attrs[name] = value
+
+    def __repr__(self):
+        return '<Namespace %r>' % self.__attrs
+
+
+# does this python version support async for in and async generators?
+try:
+    exec('async def _():\n async for _ in ():\n  yield _')
+    have_async_gen = True
+except SyntaxError:
+    have_async_gen = False
+
+
+# Imported here because that's where it was in the past
+from markupsafe import Markup, escape, soft_unicode
diff --git a/python/jinja2/visitor.py b/python/jinja2/visitor.py
new file mode 100644
index 0000000..ba526df
--- /dev/null
+++ b/python/jinja2/visitor.py
@@ -0,0 +1,87 @@
+# -*- coding: utf-8 -*-
+"""
+    jinja2.visitor
+    ~~~~~~~~~~~~~~
+
+    This module implements a visitor for the nodes.
+
+    :copyright: (c) 2017 by the Jinja Team.
+    :license: BSD.
+"""
+from jinja2.nodes import Node
+
+
+class NodeVisitor(object):
+    """Walks the abstract syntax tree and call visitor functions for every
+    node found.  The visitor functions may return values which will be
+    forwarded by the `visit` method.
+
+    Per default the visitor functions for the nodes are ``'visit_'`` +
+    class name of the node.  So a `TryFinally` node visit function would
+    be `visit_TryFinally`.  This behavior can be changed by overriding
+    the `get_visitor` function.  If no visitor function exists for a node
+    (return value `None`) the `generic_visit` visitor is used instead.
+    """
+
+    def get_visitor(self, node):
+        """Return the visitor function for this node or `None` if no visitor
+        exists for this node.  In that case the generic visit function is
+        used instead.
+        """
+        method = 'visit_' + node.__class__.__name__
+        return getattr(self, method, None)
+
+    def visit(self, node, *args, **kwargs):
+        """Visit a node."""
+        f = self.get_visitor(node)
+        if f is not None:
+            return f(node, *args, **kwargs)
+        return self.generic_visit(node, *args, **kwargs)
+
+    def generic_visit(self, node, *args, **kwargs):
+        """Called if no explicit visitor function exists for a node."""
+        for node in node.iter_child_nodes():
+            self.visit(node, *args, **kwargs)
+
+
+class NodeTransformer(NodeVisitor):
+    """Walks the abstract syntax tree and allows modifications of nodes.
+
+    The `NodeTransformer` will walk the AST and use the return value of the
+    visitor functions to replace or remove the old node.  If the return
+    value of the visitor function is `None` the node will be removed
+    from the previous location otherwise it's replaced with the return
+    value.  The return value may be the original node in which case no
+    replacement takes place.
+    """
+
+    def generic_visit(self, node, *args, **kwargs):
+        for field, old_value in node.iter_fields():
+            if isinstance(old_value, list):
+                new_values = []
+                for value in old_value:
+                    if isinstance(value, Node):
+                        value = self.visit(value, *args, **kwargs)
+                        if value is None:
+                            continue
+                        elif not isinstance(value, Node):
+                            new_values.extend(value)
+                            continue
+                    new_values.append(value)
+                old_value[:] = new_values
+            elif isinstance(old_value, Node):
+                new_node = self.visit(old_value, *args, **kwargs)
+                if new_node is None:
+                    delattr(node, field)
+                else:
+                    setattr(node, field, new_node)
+        return node
+
+    def visit_list(self, node, *args, **kwargs):
+        """As transformers may return lists in some places this method
+        can be used to enforce a list as return value.
+        """
+        rv = self.visit(node, *args, **kwargs)
+        if not isinstance(rv, list):
+            rv = [rv]
+        return rv
diff --git a/python/markupsafe/__init__.py b/python/markupsafe/__init__.py
new file mode 100644
index 0000000..68dc85f
--- /dev/null
+++ b/python/markupsafe/__init__.py
@@ -0,0 +1,305 @@
+# -*- coding: utf-8 -*-
+"""
+    markupsafe
+    ~~~~~~~~~~
+
+    Implements a Markup string.
+
+    :copyright: (c) 2010 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+import re
+import string
+from collections import Mapping
+from markupsafe._compat import text_type, string_types, int_types, \
+     unichr, iteritems, PY2
+
+__version__ = "1.0"
+
+__all__ = ['Markup', 'soft_unicode', 'escape', 'escape_silent']
+
+
+_striptags_re = re.compile(r'(<!--.*?-->|<[^>]*>)')
+_entity_re = re.compile(r'&([^& ;]+);')
+
+
+class Markup(text_type):
+    r"""Marks a string as being safe for inclusion in HTML/XML output without
+    needing to be escaped.  This implements the `__html__` interface a couple
+    of frameworks and web applications use.  :class:`Markup` is a direct
+    subclass of `unicode` and provides all the methods of `unicode` just that
+    it escapes arguments passed and always returns `Markup`.
+
+    The `escape` function returns markup objects so that double escaping can't
+    happen.
+
+    The constructor of the :class:`Markup` class can be used for three
+    different things:  When passed an unicode object it's assumed to be safe,
+    when passed an object with an HTML representation (has an `__html__`
+    method) that representation is used, otherwise the object passed is
+    converted into a unicode string and then assumed to be safe:
+
+    >>> Markup("Hello <em>World</em>!")
+    Markup(u'Hello <em>World</em>!')
+    >>> class Foo(object):
+    ...  def __html__(self):
+    ...   return '<a href="#">foo</a>'
+    ...
+    >>> Markup(Foo())
+    Markup(u'<a href="#">foo</a>')
+
+    If you want object passed being always treated as unsafe you can use the
+    :meth:`escape` classmethod to create a :class:`Markup` object:
+
+    >>> Markup.escape("Hello <em>World</em>!")
+    Markup(u'Hello &lt;em&gt;World&lt;/em&gt;!')
+
+    Operations on a markup string are markup aware which means that all
+    arguments are passed through the :func:`escape` function:
+
+    >>> em = Markup("<em>%s</em>")
+    >>> em % "foo & bar"
+    Markup(u'<em>foo &amp; bar</em>')
+    >>> strong = Markup("<strong>%(text)s</strong>")
+    >>> strong % {'text': '<blink>hacker here</blink>'}
+    Markup(u'<strong>&lt;blink&gt;hacker here&lt;/blink&gt;</strong>')
+    >>> Markup("<em>Hello</em> ") + "<foo>"
+    Markup(u'<em>Hello</em> &lt;foo&gt;')
+    """
+    __slots__ = ()
+
+    def __new__(cls, base=u'', encoding=None, errors='strict'):
+        if hasattr(base, '__html__'):
+            base = base.__html__()
+        if encoding is None:
+            return text_type.__new__(cls, base)
+        return text_type.__new__(cls, base, encoding, errors)
+
+    def __html__(self):
+        return self
+
+    def __add__(self, other):
+        if isinstance(other, string_types) or hasattr(other, '__html__'):
+            return self.__class__(super(Markup, self).__add__(self.escape(other)))
+        return NotImplemented
+
+    def __radd__(self, other):
+        if hasattr(other, '__html__') or isinstance(other, string_types):
+            return self.escape(other).__add__(self)
+        return NotImplemented
+
+    def __mul__(self, num):
+        if isinstance(num, int_types):
+            return self.__class__(text_type.__mul__(self, num))
+        return NotImplemented
+    __rmul__ = __mul__
+
+    def __mod__(self, arg):
+        if isinstance(arg, tuple):
+            arg = tuple(_MarkupEscapeHelper(x, self.escape) for x in arg)
+        else:
+            arg = _MarkupEscapeHelper(arg, self.escape)
+        return self.__class__(text_type.__mod__(self, arg))
+
+    def __repr__(self):
+        return '%s(%s)' % (
+            self.__class__.__name__,
+            text_type.__repr__(self)
+        )
+
+    def join(self, seq):
+        return self.__class__(text_type.join(self, map(self.escape, seq)))
+    join.__doc__ = text_type.join.__doc__
+
+    def split(self, *args, **kwargs):
+        return list(map(self.__class__, text_type.split(self, *args, **kwargs)))
+    split.__doc__ = text_type.split.__doc__
+
+    def rsplit(self, *args, **kwargs):
+        return list(map(self.__class__, text_type.rsplit(self, *args, **kwargs)))
+    rsplit.__doc__ = text_type.rsplit.__doc__
+
+    def splitlines(self, *args, **kwargs):
+        return list(map(self.__class__, text_type.splitlines(
+            self, *args, **kwargs)))
+    splitlines.__doc__ = text_type.splitlines.__doc__
+
+    def unescape(self):
+        r"""Unescape markup again into an text_type string.  This also resolves
+        known HTML4 and XHTML entities:
+
+        >>> Markup("Main &raquo; <em>About</em>").unescape()
+        u'Main \xbb <em>About</em>'
+        """
+        from markupsafe._constants import HTML_ENTITIES
+        def handle_match(m):
+            name = m.group(1)
+            if name in HTML_ENTITIES:
+                return unichr(HTML_ENTITIES[name])
+            try:
+                if name[:2] in ('#x', '#X'):
+                    return unichr(int(name[2:], 16))
+                elif name.startswith('#'):
+                    return unichr(int(name[1:]))
+            except ValueError:
+                pass
+            # Don't modify unexpected input.
+            return m.group()
+        return _entity_re.sub(handle_match, text_type(self))
+
+    def striptags(self):
+        r"""Unescape markup into an text_type string and strip all tags.  This
+        also resolves known HTML4 and XHTML entities.  Whitespace is
+        normalized to one:
+
+        >>> Markup("Main &raquo;  <em>About</em>").striptags()
+        u'Main \xbb About'
+        """
+        stripped = u' '.join(_striptags_re.sub('', self).split())
+        return Markup(stripped).unescape()
+
+    @classmethod
+    def escape(cls, s):
+        """Escape the string.  Works like :func:`escape` with the difference
+        that for subclasses of :class:`Markup` this function would return the
+        correct subclass.
+        """
+        rv = escape(s)
+        if rv.__class__ is not cls:
+            return cls(rv)
+        return rv
+
+    def make_simple_escaping_wrapper(name):
+        orig = getattr(text_type, name)
+        def func(self, *args, **kwargs):
+            args = _escape_argspec(list(args), enumerate(args), self.escape)
+            _escape_argspec(kwargs, iteritems(kwargs), self.escape)
+            return self.__class__(orig(self, *args, **kwargs))
+        func.__name__ = orig.__name__
+        func.__doc__ = orig.__doc__
+        return func
+
+    for method in '__getitem__', 'capitalize', \
+                  'title', 'lower', 'upper', 'replace', 'ljust', \
+                  'rjust', 'lstrip', 'rstrip', 'center', 'strip', \
+                  'translate', 'expandtabs', 'swapcase', 'zfill':
+        locals()[method] = make_simple_escaping_wrapper(method)
+
+    # new in python 2.5
+    if hasattr(text_type, 'partition'):
+        def partition(self, sep):
+            return tuple(map(self.__class__,
+                             text_type.partition(self, self.escape(sep))))
+        def rpartition(self, sep):
+            return tuple(map(self.__class__,
+                             text_type.rpartition(self, self.escape(sep))))
+
+    # new in python 2.6
+    if hasattr(text_type, 'format'):
+        def format(*args, **kwargs):
+            self, args = args[0], args[1:]
+            formatter = EscapeFormatter(self.escape)
+            kwargs = _MagicFormatMapping(args, kwargs)
+            return self.__class__(formatter.vformat(self, args, kwargs))
+
+        def __html_format__(self, format_spec):
+            if format_spec:
+                raise ValueError('Unsupported format specification '
+                                 'for Markup.')
+            return self
+
+    # not in python 3
+    if hasattr(text_type, '__getslice__'):
+        __getslice__ = make_simple_escaping_wrapper('__getslice__')
+
+    del method, make_simple_escaping_wrapper
+
+
+class _MagicFormatMapping(Mapping):
+    """This class implements a dummy wrapper to fix a bug in the Python
+    standard library for string formatting.
+
+    See http://bugs.python.org/issue13598 for information about why
+    this is necessary.
+    """
+
+    def __init__(self, args, kwargs):
+        self._args = args
+        self._kwargs = kwargs
+        self._last_index = 0
+
+    def __getitem__(self, key):
+        if key == '':
+            idx = self._last_index
+            self._last_index += 1
+            try:
+                return self._args[idx]
+            except LookupError:
+                pass
+            key = str(idx)
+        return self._kwargs[key]
+
+    def __iter__(self):
+        return iter(self._kwargs)
+
+    def __len__(self):
+        return len(self._kwargs)
+
+
+if hasattr(text_type, 'format'):
+    class EscapeFormatter(string.Formatter):
+
+        def __init__(self, escape):
+            self.escape = escape
+
+        def format_field(self, value, format_spec):
+            if hasattr(value, '__html_format__'):
+                rv = value.__html_format__(format_spec)
+            elif hasattr(value, '__html__'):
+                if format_spec:
+                    raise ValueError('No format specification allowed '
+                                     'when formatting an object with '
+                                     'its __html__ method.')
+                rv = value.__html__()
+            else:
+                # We need to make sure the format spec is unicode here as
+                # otherwise the wrong callback methods are invoked.  For
+                # instance a byte string there would invoke __str__ and
+                # not __unicode__.
+                rv = string.Formatter.format_field(
+                    self, value, text_type(format_spec))
+            return text_type(self.escape(rv))
+
+
+def _escape_argspec(obj, iterable, escape):
+    """Helper for various string-wrapped functions."""
+    for key, value in iterable:
+        if hasattr(value, '__html__') or isinstance(value, string_types):
+            obj[key] = escape(value)
+    return obj
+
+
+class _MarkupEscapeHelper(object):
+    """Helper for Markup.__mod__"""
+
+    def __init__(self, obj, escape):
+        self.obj = obj
+        self.escape = escape
+
+    __getitem__ = lambda s, x: _MarkupEscapeHelper(s.obj[x], s.escape)
+    __unicode__ = __str__ = lambda s: text_type(s.escape(s.obj))
+    __repr__ = lambda s: str(s.escape(repr(s.obj)))
+    __int__ = lambda s: int(s.obj)
+    __float__ = lambda s: float(s.obj)
+
+
+# we have to import it down here as the speedups and native
+# modules imports the markup type which is define above.
+try:
+    from markupsafe._speedups import escape, escape_silent, soft_unicode
+except ImportError:
+    from markupsafe._native import escape, escape_silent, soft_unicode
+
+if not PY2:
+    soft_str = soft_unicode
+    __all__.append('soft_str')
diff --git a/python/markupsafe/_compat.py b/python/markupsafe/_compat.py
new file mode 100644
index 0000000..62e5632
--- /dev/null
+++ b/python/markupsafe/_compat.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+"""
+    markupsafe._compat
+    ~~~~~~~~~~~~~~~~~~
+
+    Compatibility module for different Python versions.
+
+    :copyright: (c) 2013 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+if not PY2:
+    text_type = str
+    string_types = (str,)
+    unichr = chr
+    int_types = (int,)
+    iteritems = lambda x: iter(x.items())
+else:
+    text_type = unicode
+    string_types = (str, unicode)
+    unichr = unichr
+    int_types = (int, long)
+    iteritems = lambda x: x.iteritems()
diff --git a/python/markupsafe/_constants.py b/python/markupsafe/_constants.py
new file mode 100644
index 0000000..919bf03
--- /dev/null
+++ b/python/markupsafe/_constants.py
@@ -0,0 +1,267 @@
+# -*- coding: utf-8 -*-
+"""
+    markupsafe._constants
+    ~~~~~~~~~~~~~~~~~~~~~
+
+    Highlevel implementation of the Markup string.
+
+    :copyright: (c) 2010 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+
+
+HTML_ENTITIES = {
+    'AElig': 198,
+    'Aacute': 193,
+    'Acirc': 194,
+    'Agrave': 192,
+    'Alpha': 913,
+    'Aring': 197,
+    'Atilde': 195,
+    'Auml': 196,
+    'Beta': 914,
+    'Ccedil': 199,
+    'Chi': 935,
+    'Dagger': 8225,
+    'Delta': 916,
+    'ETH': 208,
+    'Eacute': 201,
+    'Ecirc': 202,
+    'Egrave': 200,
+    'Epsilon': 917,
+    'Eta': 919,
+    'Euml': 203,
+    'Gamma': 915,
+    'Iacute': 205,
+    'Icirc': 206,
+    'Igrave': 204,
+    'Iota': 921,
+    'Iuml': 207,
+    'Kappa': 922,
+    'Lambda': 923,
+    'Mu': 924,
+    'Ntilde': 209,
+    'Nu': 925,
+    'OElig': 338,
+    'Oacute': 211,
+    'Ocirc': 212,
+    'Ograve': 210,
+    'Omega': 937,
+    'Omicron': 927,
+    'Oslash': 216,
+    'Otilde': 213,
+    'Ouml': 214,
+    'Phi': 934,
+    'Pi': 928,
+    'Prime': 8243,
+    'Psi': 936,
+    'Rho': 929,
+    'Scaron': 352,
+    'Sigma': 931,
+    'THORN': 222,
+    'Tau': 932,
+    'Theta': 920,
+    'Uacute': 218,
+    'Ucirc': 219,
+    'Ugrave': 217,
+    'Upsilon': 933,
+    'Uuml': 220,
+    'Xi': 926,
+    'Yacute': 221,
+    'Yuml': 376,
+    'Zeta': 918,
+    'aacute': 225,
+    'acirc': 226,
+    'acute': 180,
+    'aelig': 230,
+    'agrave': 224,
+    'alefsym': 8501,
+    'alpha': 945,
+    'amp': 38,
+    'and': 8743,
+    'ang': 8736,
+    'apos': 39,
+    'aring': 229,
+    'asymp': 8776,
+    'atilde': 227,
+    'auml': 228,
+    'bdquo': 8222,
+    'beta': 946,
+    'brvbar': 166,
+    'bull': 8226,
+    'cap': 8745,
+    'ccedil': 231,
+    'cedil': 184,
+    'cent': 162,
+    'chi': 967,
+    'circ': 710,
+    'clubs': 9827,
+    'cong': 8773,
+    'copy': 169,
+    'crarr': 8629,
+    'cup': 8746,
+    'curren': 164,
+    'dArr': 8659,
+    'dagger': 8224,
+    'darr': 8595,
+    'deg': 176,
+    'delta': 948,
+    'diams': 9830,
+    'divide': 247,
+    'eacute': 233,
+    'ecirc': 234,
+    'egrave': 232,
+    'empty': 8709,
+    'emsp': 8195,
+    'ensp': 8194,
+    'epsilon': 949,
+    'equiv': 8801,
+    'eta': 951,
+    'eth': 240,
+    'euml': 235,
+    'euro': 8364,
+    'exist': 8707,
+    'fnof': 402,
+    'forall': 8704,
+    'frac12': 189,
+    'frac14': 188,
+    'frac34': 190,
+    'frasl': 8260,
+    'gamma': 947,
+    'ge': 8805,
+    'gt': 62,
+    'hArr': 8660,
+    'harr': 8596,
+    'hearts': 9829,
+    'hellip': 8230,
+    'iacute': 237,
+    'icirc': 238,
+    'iexcl': 161,
+    'igrave': 236,
+    'image': 8465,
+    'infin': 8734,
+    'int': 8747,
+    'iota': 953,
+    'iquest': 191,
+    'isin': 8712,
+    'iuml': 239,
+    'kappa': 954,
+    'lArr': 8656,
+    'lambda': 955,
+    'lang': 9001,
+    'laquo': 171,
+    'larr': 8592,
+    'lceil': 8968,
+    'ldquo': 8220,
+    'le': 8804,
+    'lfloor': 8970,
+    'lowast': 8727,
+    'loz': 9674,
+    'lrm': 8206,
+    'lsaquo': 8249,
+    'lsquo': 8216,
+    'lt': 60,
+    'macr': 175,
+    'mdash': 8212,
+    'micro': 181,
+    'middot': 183,
+    'minus': 8722,
+    'mu': 956,
+    'nabla': 8711,
+    'nbsp': 160,
+    'ndash': 8211,
+    'ne': 8800,
+    'ni': 8715,
+    'not': 172,
+    'notin': 8713,
+    'nsub': 8836,
+    'ntilde': 241,
+    'nu': 957,
+    'oacute': 243,
+    'ocirc': 244,
+    'oelig': 339,
+    'ograve': 242,
+    'oline': 8254,
+    'omega': 969,
+    'omicron': 959,
+    'oplus': 8853,
+    'or': 8744,
+    'ordf': 170,
+    'ordm': 186,
+    'oslash': 248,
+    'otilde': 245,
+    'otimes': 8855,
+    'ouml': 246,
+    'para': 182,
+    'part': 8706,
+    'permil': 8240,
+    'perp': 8869,
+    'phi': 966,
+    'pi': 960,
+    'piv': 982,
+    'plusmn': 177,
+    'pound': 163,
+    'prime': 8242,
+    'prod': 8719,
+    'prop': 8733,
+    'psi': 968,
+    'quot': 34,
+    'rArr': 8658,
+    'radic': 8730,
+    'rang': 9002,
+    'raquo': 187,
+    'rarr': 8594,
+    'rceil': 8969,
+    'rdquo': 8221,
+    'real': 8476,
+    'reg': 174,
+    'rfloor': 8971,
+    'rho': 961,
+    'rlm': 8207,
+    'rsaquo': 8250,
+    'rsquo': 8217,
+    'sbquo': 8218,
+    'scaron': 353,
+    'sdot': 8901,
+    'sect': 167,
+    'shy': 173,
+    'sigma': 963,
+    'sigmaf': 962,
+    'sim': 8764,
+    'spades': 9824,
+    'sub': 8834,
+    'sube': 8838,
+    'sum': 8721,
+    'sup': 8835,
+    'sup1': 185,
+    'sup2': 178,
+    'sup3': 179,
+    'supe': 8839,
+    'szlig': 223,
+    'tau': 964,
+    'there4': 8756,
+    'theta': 952,
+    'thetasym': 977,
+    'thinsp': 8201,
+    'thorn': 254,
+    'tilde': 732,
+    'times': 215,
+    'trade': 8482,
+    'uArr': 8657,
+    'uacute': 250,
+    'uarr': 8593,
+    'ucirc': 251,
+    'ugrave': 249,
+    'uml': 168,
+    'upsih': 978,
+    'upsilon': 965,
+    'uuml': 252,
+    'weierp': 8472,
+    'xi': 958,
+    'yacute': 253,
+    'yen': 165,
+    'yuml': 255,
+    'zeta': 950,
+    'zwj': 8205,
+    'zwnj': 8204
+}
diff --git a/python/markupsafe/_native.py b/python/markupsafe/_native.py
new file mode 100644
index 0000000..5e83f10
--- /dev/null
+++ b/python/markupsafe/_native.py
@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+"""
+    markupsafe._native
+    ~~~~~~~~~~~~~~~~~~
+
+    Native Python implementation the C module is not compiled.
+
+    :copyright: (c) 2010 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+from markupsafe import Markup
+from markupsafe._compat import text_type
+
+
+def escape(s):
+    """Convert the characters &, <, >, ' and " in string s to HTML-safe
+    sequences.  Use this if you need to display text that might contain
+    such characters in HTML.  Marks return value as markup string.
+    """
+    if hasattr(s, '__html__'):
+        return s.__html__()
+    return Markup(text_type(s)
+        .replace('&', '&amp;')
+        .replace('>', '&gt;')
+        .replace('<', '&lt;')
+        .replace("'", '&#39;')
+        .replace('"', '&#34;')
+    )
+
+
+def escape_silent(s):
+    """Like :func:`escape` but converts `None` into an empty
+    markup string.
+    """
+    if s is None:
+        return Markup()
+    return escape(s)
+
+
+def soft_unicode(s):
+    """Make a string unicode if it isn't already.  That way a markup
+    string is not converted back to unicode.
+    """
+    if not isinstance(s, text_type):
+        s = text_type(s)
+    return s
diff --git a/python/markupsafe/_speedups.c b/python/markupsafe/_speedups.c
new file mode 100644
index 0000000..d779a68
--- /dev/null
+++ b/python/markupsafe/_speedups.c
@@ -0,0 +1,239 @@
+/**
+ * markupsafe._speedups
+ * ~~~~~~~~~~~~~~~~~~~~
+ *
+ * This module implements functions for automatic escaping in C for better
+ * performance.
+ *
+ * :copyright: (c) 2010 by Armin Ronacher.
+ * :license: BSD.
+ */
+
+#include <Python.h>
+
+#define ESCAPED_CHARS_TABLE_SIZE 63
+#define UNICHR(x) (PyUnicode_AS_UNICODE((PyUnicodeObject*)PyUnicode_DecodeASCII(x, strlen(x), NULL)));
+
+#if PY_VERSION_HEX < 0x02050000 && !defined(PY_SSIZE_T_MIN)
+typedef int Py_ssize_t;
+#define PY_SSIZE_T_MAX INT_MAX
+#define PY_SSIZE_T_MIN INT_MIN
+#endif
+
+
+static PyObject* markup;
+static Py_ssize_t escaped_chars_delta_len[ESCAPED_CHARS_TABLE_SIZE];
+static Py_UNICODE *escaped_chars_repl[ESCAPED_CHARS_TABLE_SIZE];
+
+static int
+init_constants(void)
+{
+	PyObject *module;
+	/* mapping of characters to replace */
+	escaped_chars_repl['"'] = UNICHR("&#34;");
+	escaped_chars_repl['\''] = UNICHR("&#39;");
+	escaped_chars_repl['&'] = UNICHR("&amp;");
+	escaped_chars_repl['<'] = UNICHR("&lt;");
+	escaped_chars_repl['>'] = UNICHR("&gt;");
+
+	/* lengths of those characters when replaced - 1 */
+	memset(escaped_chars_delta_len, 0, sizeof (escaped_chars_delta_len));
+	escaped_chars_delta_len['"'] = escaped_chars_delta_len['\''] = \
+		escaped_chars_delta_len['&'] = 4;
+	escaped_chars_delta_len['<'] = escaped_chars_delta_len['>'] = 3;
+
+	/* import markup type so that we can mark the return value */
+	module = PyImport_ImportModule("markupsafe");
+	if (!module)
+		return 0;
+	markup = PyObject_GetAttrString(module, "Markup");
+	Py_DECREF(module);
+
+	return 1;
+}
+
+static PyObject*
+escape_unicode(PyUnicodeObject *in)
+{
+	PyUnicodeObject *out;
+	Py_UNICODE *inp = PyUnicode_AS_UNICODE(in);
+	const Py_UNICODE *inp_end = PyUnicode_AS_UNICODE(in) + PyUnicode_GET_SIZE(in);
+	Py_UNICODE *next_escp;
+	Py_UNICODE *outp;
+	Py_ssize_t delta=0, erepl=0, delta_len=0;
+
+	/* First we need to figure out how long the escaped string will be */
+	while (*(inp) || inp < inp_end) {
+		if (*inp < ESCAPED_CHARS_TABLE_SIZE) {
+			delta += escaped_chars_delta_len[*inp];
+			erepl += !!escaped_chars_delta_len[*inp];
+		}
+		++inp;
+	}
+
+	/* Do we need to escape anything at all? */
+	if (!erepl) {
+		Py_INCREF(in);
+		return (PyObject*)in;
+	}
+
+	out = (PyUnicodeObject*)PyUnicode_FromUnicode(NULL, PyUnicode_GET_SIZE(in) + delta);
+	if (!out)
+		return NULL;
+
+	outp = PyUnicode_AS_UNICODE(out);
+	inp = PyUnicode_AS_UNICODE(in);
+	while (erepl-- > 0) {
+		/* look for the next substitution */
+		next_escp = inp;
+		while (next_escp < inp_end) {
+			if (*next_escp < ESCAPED_CHARS_TABLE_SIZE &&
+			    (delta_len = escaped_chars_delta_len[*next_escp])) {
+				++delta_len;
+				break;
+			}
+			++next_escp;
+		}
+
+		if (next_escp > inp) {
+			/* copy unescaped chars between inp and next_escp */
+			Py_UNICODE_COPY(outp, inp, next_escp-inp);
+			outp += next_escp - inp;
+		}
+
+		/* escape 'next_escp' */
+		Py_UNICODE_COPY(outp, escaped_chars_repl[*next_escp], delta_len);
+		outp += delta_len;
+
+		inp = next_escp + 1;
+	}
+	if (inp < inp_end)
+		Py_UNICODE_COPY(outp, inp, PyUnicode_GET_SIZE(in) - (inp - PyUnicode_AS_UNICODE(in)));
+
+	return (PyObject*)out;
+}
+
+
+static PyObject*
+escape(PyObject *self, PyObject *text)
+{
+	PyObject *s = NULL, *rv = NULL, *html;
+
+	/* we don't have to escape integers, bools or floats */
+	if (PyLong_CheckExact(text) ||
+#if PY_MAJOR_VERSION < 3
+	    PyInt_CheckExact(text) ||
+#endif
+	    PyFloat_CheckExact(text) || PyBool_Check(text) ||
+	    text == Py_None)
+		return PyObject_CallFunctionObjArgs(markup, text, NULL);
+
+	/* if the object has an __html__ method that performs the escaping */
+	html = PyObject_GetAttrString(text, "__html__");
+	if (html) {
+		rv = PyObject_CallObject(html, NULL);
+		Py_DECREF(html);
+		return rv;
+	}
+
+	/* otherwise make the object unicode if it isn't, then escape */
+	PyErr_Clear();
+	if (!PyUnicode_Check(text)) {
+#if PY_MAJOR_VERSION < 3
+		PyObject *unicode = PyObject_Unicode(text);
+#else
+		PyObject *unicode = PyObject_Str(text);
+#endif
+		if (!unicode)
+			return NULL;
+		s = escape_unicode((PyUnicodeObject*)unicode);
+		Py_DECREF(unicode);
+	}
+	else
+		s = escape_unicode((PyUnicodeObject*)text);
+
+	/* convert the unicode string into a markup object. */
+	rv = PyObject_CallFunctionObjArgs(markup, (PyObject*)s, NULL);
+	Py_DECREF(s);
+	return rv;
+}
+
+
+static PyObject*
+escape_silent(PyObject *self, PyObject *text)
+{
+	if (text != Py_None)
+		return escape(self, text);
+	return PyObject_CallFunctionObjArgs(markup, NULL);
+}
+
+
+static PyObject*
+soft_unicode(PyObject *self, PyObject *s)
+{
+	if (!PyUnicode_Check(s))
+#if PY_MAJOR_VERSION < 3
+		return PyObject_Unicode(s);
+#else
+		return PyObject_Str(s);
+#endif
+	Py_INCREF(s);
+	return s;
+}
+
+
+static PyMethodDef module_methods[] = {
+	{"escape", (PyCFunction)escape, METH_O,
+	 "escape(s) -> markup\n\n"
+	 "Convert the characters &, <, >, ', and \" in string s to HTML-safe\n"
+	 "sequences.  Use this if you need to display text that might contain\n"
+	 "such characters in HTML.  Marks return value as markup string."},
+	{"escape_silent", (PyCFunction)escape_silent, METH_O,
+	 "escape_silent(s) -> markup\n\n"
+	 "Like escape but converts None to an empty string."},
+	{"soft_unicode", (PyCFunction)soft_unicode, METH_O,
+	 "soft_unicode(object) -> string\n\n"
+         "Make a string unicode if it isn't already.  That way a markup\n"
+         "string is not converted back to unicode."},
+	{NULL, NULL, 0, NULL}		/* Sentinel */
+};
+
+
+#if PY_MAJOR_VERSION < 3
+
+#ifndef PyMODINIT_FUNC	/* declarations for DLL import/export */
+#define PyMODINIT_FUNC void
+#endif
+PyMODINIT_FUNC
+init_speedups(void)
+{
+	if (!init_constants())
+		return;
+
+	Py_InitModule3("markupsafe._speedups", module_methods, "");
+}
+
+#else /* Python 3.x module initialization */
+
+static struct PyModuleDef module_definition = {
+        PyModuleDef_HEAD_INIT,
+	"markupsafe._speedups",
+	NULL,
+	-1,
+	module_methods,
+	NULL,
+	NULL,
+	NULL,
+	NULL
+};
+
+PyMODINIT_FUNC
+PyInit__speedups(void)
+{
+	if (!init_constants())
+		return NULL;
+
+	return PyModule_Create(&module_definition);
+}
+
+#endif
diff --git a/python/werkzeug/__init__.py b/python/werkzeug/__init__.py
new file mode 100644
index 0000000..e460e75
--- /dev/null
+++ b/python/werkzeug/__init__.py
@@ -0,0 +1,233 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug
+    ~~~~~~~~
+
+    Werkzeug is the Swiss Army knife of Python web development.
+
+    It provides useful classes and functions for any WSGI application to make
+    the life of a python web developer much easier.  All of the provided
+    classes are independent from each other so you can mix it with any other
+    library.
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import sys
+from types import ModuleType
+
+__version__ = "0.15.4"
+
+# This import magic raises concerns quite often which is why the implementation
+# and motivation is explained here in detail now.
+#
+# The majority of the functions and classes provided by Werkzeug work on the
+# HTTP and WSGI layer.  There is no useful grouping for those which is why
+# they are all importable from "werkzeug" instead of the modules where they are
+# implemented.  The downside of that is, that now everything would be loaded at
+# once, even if unused.
+#
+# The implementation of a lazy-loading module in this file replaces the
+# werkzeug package when imported from within.  Attribute access to the werkzeug
+# module will then lazily import from the modules that implement the objects.
+
+# import mapping to objects in other modules
+all_by_module = {
+    "werkzeug.debug": ["DebuggedApplication"],
+    "werkzeug.local": [
+        "Local",
+        "LocalManager",
+        "LocalProxy",
+        "LocalStack",
+        "release_local",
+    ],
+    "werkzeug.serving": ["run_simple"],
+    "werkzeug.test": ["Client", "EnvironBuilder", "create_environ", "run_wsgi_app"],
+    "werkzeug.testapp": ["test_app"],
+    "werkzeug.exceptions": ["abort", "Aborter"],
+    "werkzeug.urls": [
+        "url_decode",
+        "url_encode",
+        "url_quote",
+        "url_quote_plus",
+        "url_unquote",
+        "url_unquote_plus",
+        "url_fix",
+        "Href",
+        "iri_to_uri",
+        "uri_to_iri",
+    ],
+    "werkzeug.formparser": ["parse_form_data"],
+    "werkzeug.utils": [
+        "escape",
+        "environ_property",
+        "append_slash_redirect",
+        "redirect",
+        "cached_property",
+        "import_string",
+        "dump_cookie",
+        "parse_cookie",
+        "unescape",
+        "format_string",
+        "find_modules",
+        "header_property",
+        "html",
+        "xhtml",
+        "HTMLBuilder",
+        "validate_arguments",
+        "ArgumentValidationError",
+        "bind_arguments",
+        "secure_filename",
+    ],
+    "werkzeug.wsgi": [
+        "get_current_url",
+        "get_host",
+        "pop_path_info",
+        "peek_path_info",
+        "ClosingIterator",
+        "FileWrapper",
+        "make_line_iter",
+        "LimitedStream",
+        "responder",
+        "wrap_file",
+        "extract_path_info",
+    ],
+    "werkzeug.datastructures": [
+        "MultiDict",
+        "CombinedMultiDict",
+        "Headers",
+        "EnvironHeaders",
+        "ImmutableList",
+        "ImmutableDict",
+        "ImmutableMultiDict",
+        "TypeConversionDict",
+        "ImmutableTypeConversionDict",
+        "Accept",
+        "MIMEAccept",
+        "CharsetAccept",
+        "LanguageAccept",
+        "RequestCacheControl",
+        "ResponseCacheControl",
+        "ETags",
+        "HeaderSet",
+        "WWWAuthenticate",
+        "Authorization",
+        "FileMultiDict",
+        "CallbackDict",
+        "FileStorage",
+        "OrderedMultiDict",
+        "ImmutableOrderedMultiDict",
+    ],
+    "werkzeug.useragents": ["UserAgent"],
+    "werkzeug.http": [
+        "parse_etags",
+        "parse_date",
+        "http_date",
+        "cookie_date",
+        "parse_cache_control_header",
+        "is_resource_modified",
+        "parse_accept_header",
+        "parse_set_header",
+        "quote_etag",
+        "unquote_etag",
+        "generate_etag",
+        "dump_header",
+        "parse_list_header",
+        "parse_dict_header",
+        "parse_authorization_header",
+        "parse_www_authenticate_header",
+        "remove_entity_headers",
+        "is_entity_header",
+        "remove_hop_by_hop_headers",
+        "parse_options_header",
+        "dump_options_header",
+        "is_hop_by_hop_header",
+        "unquote_header_value",
+        "quote_header_value",
+        "HTTP_STATUS_CODES",
+    ],
+    "werkzeug.wrappers": [
+        "BaseResponse",
+        "BaseRequest",
+        "Request",
+        "Response",
+        "AcceptMixin",
+        "ETagRequestMixin",
+        "ETagResponseMixin",
+        "ResponseStreamMixin",
+        "CommonResponseDescriptorsMixin",
+        "UserAgentMixin",
+        "AuthorizationMixin",
+        "WWWAuthenticateMixin",
+        "CommonRequestDescriptorsMixin",
+    ],
+    "werkzeug.middleware.dispatcher": ["DispatcherMiddleware"],
+    "werkzeug.middleware.shared_data": ["SharedDataMiddleware"],
+    "werkzeug.security": ["generate_password_hash", "check_password_hash"],
+    # the undocumented easteregg ;-)
+    "werkzeug._internal": ["_easteregg"],
+}
+
+# modules that should be imported when accessed as attributes of werkzeug
+attribute_modules = frozenset(["exceptions", "routing"])
+
+object_origins = {}
+for module, items in all_by_module.items():
+    for item in items:
+        object_origins[item] = module
+
+
+class module(ModuleType):
+    """Automatically import objects from the modules."""
+
+    def __getattr__(self, name):
+        if name in object_origins:
+            module = __import__(object_origins[name], None, None, [name])
+            for extra_name in all_by_module[module.__name__]:
+                setattr(self, extra_name, getattr(module, extra_name))
+            return getattr(module, name)
+        elif name in attribute_modules:
+            __import__("werkzeug." + name)
+        return ModuleType.__getattribute__(self, name)
+
+    def __dir__(self):
+        """Just show what we want to show."""
+        result = list(new_module.__all__)
+        result.extend(
+            (
+                "__file__",
+                "__doc__",
+                "__all__",
+                "__docformat__",
+                "__name__",
+                "__path__",
+                "__package__",
+                "__version__",
+            )
+        )
+        return result
+
+
+# keep a reference to this module so that it's not garbage collected
+old_module = sys.modules["werkzeug"]
+
+
+# setup the new module and patch it into the dict of loaded modules
+new_module = sys.modules["werkzeug"] = module("werkzeug")
+new_module.__dict__.update(
+    {
+        "__file__": __file__,
+        "__package__": "werkzeug",
+        "__path__": __path__,
+        "__doc__": __doc__,
+        "__version__": __version__,
+        "__all__": tuple(object_origins) + tuple(attribute_modules),
+        "__docformat__": "restructuredtext en",
+    }
+)
+
+
+# Due to bootstrapping issues we need to import exceptions here.
+# Don't ask :-(
+__import__("werkzeug.exceptions")
diff --git a/python/werkzeug/_compat.py b/python/werkzeug/_compat.py
new file mode 100644
index 0000000..1097983
--- /dev/null
+++ b/python/werkzeug/_compat.py
@@ -0,0 +1,219 @@
+# flake8: noqa
+# This whole file is full of lint errors
+import functools
+import operator
+import sys
+
+try:
+    import builtins
+except ImportError:
+    import __builtin__ as builtins
+
+
+PY2 = sys.version_info[0] == 2
+WIN = sys.platform.startswith("win")
+
+_identity = lambda x: x
+
+if PY2:
+    unichr = unichr
+    text_type = unicode
+    string_types = (str, unicode)
+    integer_types = (int, long)
+
+    iterkeys = lambda d, *args, **kwargs: d.iterkeys(*args, **kwargs)
+    itervalues = lambda d, *args, **kwargs: d.itervalues(*args, **kwargs)
+    iteritems = lambda d, *args, **kwargs: d.iteritems(*args, **kwargs)
+
+    iterlists = lambda d, *args, **kwargs: d.iterlists(*args, **kwargs)
+    iterlistvalues = lambda d, *args, **kwargs: d.iterlistvalues(*args, **kwargs)
+
+    int_to_byte = chr
+    iter_bytes = iter
+
+    import collections as collections_abc
+
+    exec("def reraise(tp, value, tb=None):\n raise tp, value, tb")
+
+    def fix_tuple_repr(obj):
+        def __repr__(self):
+            cls = self.__class__
+            return "%s(%s)" % (
+                cls.__name__,
+                ", ".join(
+                    "%s=%r" % (field, self[index])
+                    for index, field in enumerate(cls._fields)
+                ),
+            )
+
+        obj.__repr__ = __repr__
+        return obj
+
+    def implements_iterator(cls):
+        cls.next = cls.__next__
+        del cls.__next__
+        return cls
+
+    def implements_to_string(cls):
+        cls.__unicode__ = cls.__str__
+        cls.__str__ = lambda x: x.__unicode__().encode("utf-8")
+        return cls
+
+    def native_string_result(func):
+        def wrapper(*args, **kwargs):
+            return func(*args, **kwargs).encode("utf-8")
+
+        return functools.update_wrapper(wrapper, func)
+
+    def implements_bool(cls):
+        cls.__nonzero__ = cls.__bool__
+        del cls.__bool__
+        return cls
+
+    from itertools import imap, izip, ifilter
+
+    range_type = xrange
+
+    from StringIO import StringIO
+    from cStringIO import StringIO as BytesIO
+
+    NativeStringIO = BytesIO
+
+    def make_literal_wrapper(reference):
+        return _identity
+
+    def normalize_string_tuple(tup):
+        """Normalizes a string tuple to a common type. Following Python 2
+        rules, upgrades to unicode are implicit.
+        """
+        if any(isinstance(x, text_type) for x in tup):
+            return tuple(to_unicode(x) for x in tup)
+        return tup
+
+    def try_coerce_native(s):
+        """Try to coerce a unicode string to native if possible. Otherwise,
+        leave it as unicode.
+        """
+        try:
+            return to_native(s)
+        except UnicodeError:
+            return s
+
+    wsgi_get_bytes = _identity
+
+    def wsgi_decoding_dance(s, charset="utf-8", errors="replace"):
+        return s.decode(charset, errors)
+
+    def wsgi_encoding_dance(s, charset="utf-8", errors="replace"):
+        if isinstance(s, bytes):
+            return s
+        return s.encode(charset, errors)
+
+    def to_bytes(x, charset=sys.getdefaultencoding(), errors="strict"):
+        if x is None:
+            return None
+        if isinstance(x, (bytes, bytearray, buffer)):
+            return bytes(x)
+        if isinstance(x, unicode):
+            return x.encode(charset, errors)
+        raise TypeError("Expected bytes")
+
+    def to_native(x, charset=sys.getdefaultencoding(), errors="strict"):
+        if x is None or isinstance(x, str):
+            return x
+        return x.encode(charset, errors)
+
+
+else:
+    unichr = chr
+    text_type = str
+    string_types = (str,)
+    integer_types = (int,)
+
+    iterkeys = lambda d, *args, **kwargs: iter(d.keys(*args, **kwargs))
+    itervalues = lambda d, *args, **kwargs: iter(d.values(*args, **kwargs))
+    iteritems = lambda d, *args, **kwargs: iter(d.items(*args, **kwargs))
+
+    iterlists = lambda d, *args, **kwargs: iter(d.lists(*args, **kwargs))
+    iterlistvalues = lambda d, *args, **kwargs: iter(d.listvalues(*args, **kwargs))
+
+    int_to_byte = operator.methodcaller("to_bytes", 1, "big")
+    iter_bytes = functools.partial(map, int_to_byte)
+
+    import collections.abc as collections_abc
+
+    def reraise(tp, value, tb=None):
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+
+    fix_tuple_repr = _identity
+    implements_iterator = _identity
+    implements_to_string = _identity
+    implements_bool = _identity
+    native_string_result = _identity
+    imap = map
+    izip = zip
+    ifilter = filter
+    range_type = range
+
+    from io import StringIO, BytesIO
+
+    NativeStringIO = StringIO
+
+    _latin1_encode = operator.methodcaller("encode", "latin1")
+
+    def make_literal_wrapper(reference):
+        if isinstance(reference, text_type):
+            return _identity
+        return _latin1_encode
+
+    def normalize_string_tuple(tup):
+        """Ensures that all types in the tuple are either strings
+        or bytes.
+        """
+        tupiter = iter(tup)
+        is_text = isinstance(next(tupiter, None), text_type)
+        for arg in tupiter:
+            if isinstance(arg, text_type) != is_text:
+                raise TypeError(
+                    "Cannot mix str and bytes arguments (got %s)" % repr(tup)
+                )
+        return tup
+
+    try_coerce_native = _identity
+    wsgi_get_bytes = _latin1_encode
+
+    def wsgi_decoding_dance(s, charset="utf-8", errors="replace"):
+        return s.encode("latin1").decode(charset, errors)
+
+    def wsgi_encoding_dance(s, charset="utf-8", errors="replace"):
+        if isinstance(s, text_type):
+            s = s.encode(charset)
+        return s.decode("latin1", errors)
+
+    def to_bytes(x, charset=sys.getdefaultencoding(), errors="strict"):
+        if x is None:
+            return None
+        if isinstance(x, (bytes, bytearray, memoryview)):  # noqa
+            return bytes(x)
+        if isinstance(x, str):
+            return x.encode(charset, errors)
+        raise TypeError("Expected bytes")
+
+    def to_native(x, charset=sys.getdefaultencoding(), errors="strict"):
+        if x is None or isinstance(x, str):
+            return x
+        return x.decode(charset, errors)
+
+
+def to_unicode(
+    x, charset=sys.getdefaultencoding(), errors="strict", allow_none_charset=False
+):
+    if x is None:
+        return None
+    if not isinstance(x, bytes):
+        return text_type(x)
+    if charset is None and allow_none_charset:
+        return x
+    return x.decode(charset, errors)
diff --git a/python/werkzeug/_internal.py b/python/werkzeug/_internal.py
new file mode 100644
index 0000000..90e3dd9
--- /dev/null
+++ b/python/werkzeug/_internal.py
@@ -0,0 +1,484 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug._internal
+    ~~~~~~~~~~~~~~~~~~
+
+    This module provides internally used helpers and constants.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import inspect
+import logging
+import re
+import string
+from datetime import date
+from datetime import datetime
+from itertools import chain
+from weakref import WeakKeyDictionary
+
+from ._compat import int_to_byte
+from ._compat import integer_types
+from ._compat import iter_bytes
+from ._compat import range_type
+from ._compat import text_type
+
+
+_logger = None
+_signature_cache = WeakKeyDictionary()
+_epoch_ord = date(1970, 1, 1).toordinal()
+_cookie_params = {
+    b"expires",
+    b"path",
+    b"comment",
+    b"max-age",
+    b"secure",
+    b"httponly",
+    b"version",
+}
+_legal_cookie_chars = (
+    string.ascii_letters + string.digits + u"/=!#$%&'*+-.^_`|~:"
+).encode("ascii")
+
+_cookie_quoting_map = {b",": b"\\054", b";": b"\\073", b'"': b'\\"', b"\\": b"\\\\"}
+for _i in chain(range_type(32), range_type(127, 256)):
+    _cookie_quoting_map[int_to_byte(_i)] = ("\\%03o" % _i).encode("latin1")
+
+_octal_re = re.compile(br"\\[0-3][0-7][0-7]")
+_quote_re = re.compile(br"[\\].")
+_legal_cookie_chars_re = br"[\w\d!#%&\'~_`><@,:/\$\*\+\-\.\^\|\)\(\?\}\{\=]"
+_cookie_re = re.compile(
+    br"""
+    (?P<key>[^=;]+)
+    (?:\s*=\s*
+        (?P<val>
+            "(?:[^\\"]|\\.)*" |
+             (?:.*?)
+        )
+    )?
+    \s*;
+""",
+    flags=re.VERBOSE,
+)
+
+
+class _Missing(object):
+    def __repr__(self):
+        return "no value"
+
+    def __reduce__(self):
+        return "_missing"
+
+
+_missing = _Missing()
+
+
+def _get_environ(obj):
+    env = getattr(obj, "environ", obj)
+    assert isinstance(env, dict), (
+        "%r is not a WSGI environment (has to be a dict)" % type(obj).__name__
+    )
+    return env
+
+
+def _has_level_handler(logger):
+    """Check if there is a handler in the logging chain that will handle
+    the given logger's effective level.
+    """
+    level = logger.getEffectiveLevel()
+    current = logger
+
+    while current:
+        if any(handler.level <= level for handler in current.handlers):
+            return True
+
+        if not current.propagate:
+            break
+
+        current = current.parent
+
+    return False
+
+
+def _log(type, message, *args, **kwargs):
+    """Log a message to the 'werkzeug' logger.
+
+    The logger is created the first time it is needed. If there is no
+    level set, it is set to :data:`logging.INFO`. If there is no handler
+    for the logger's effective level, a :class:`logging.StreamHandler`
+    is added.
+    """
+    global _logger
+
+    if _logger is None:
+        _logger = logging.getLogger("werkzeug")
+
+        if _logger.level == logging.NOTSET:
+            _logger.setLevel(logging.INFO)
+
+        if not _has_level_handler(_logger):
+            _logger.addHandler(logging.StreamHandler())
+
+    getattr(_logger, type)(message.rstrip(), *args, **kwargs)
+
+
+def _parse_signature(func):
+    """Return a signature object for the function."""
+    if hasattr(func, "im_func"):
+        func = func.im_func
+
+    # if we have a cached validator for this function, return it
+    parse = _signature_cache.get(func)
+    if parse is not None:
+        return parse
+
+    # inspect the function signature and collect all the information
+    if hasattr(inspect, "getfullargspec"):
+        tup = inspect.getfullargspec(func)
+    else:
+        tup = inspect.getargspec(func)
+    positional, vararg_var, kwarg_var, defaults = tup[:4]
+    defaults = defaults or ()
+    arg_count = len(positional)
+    arguments = []
+    for idx, name in enumerate(positional):
+        if isinstance(name, list):
+            raise TypeError(
+                "cannot parse functions that unpack tuples in the function signature"
+            )
+        try:
+            default = defaults[idx - arg_count]
+        except IndexError:
+            param = (name, False, None)
+        else:
+            param = (name, True, default)
+        arguments.append(param)
+    arguments = tuple(arguments)
+
+    def parse(args, kwargs):
+        new_args = []
+        missing = []
+        extra = {}
+
+        # consume as many arguments as positional as possible
+        for idx, (name, has_default, default) in enumerate(arguments):
+            try:
+                new_args.append(args[idx])
+            except IndexError:
+                try:
+                    new_args.append(kwargs.pop(name))
+                except KeyError:
+                    if has_default:
+                        new_args.append(default)
+                    else:
+                        missing.append(name)
+            else:
+                if name in kwargs:
+                    extra[name] = kwargs.pop(name)
+
+        # handle extra arguments
+        extra_positional = args[arg_count:]
+        if vararg_var is not None:
+            new_args.extend(extra_positional)
+            extra_positional = ()
+        if kwargs and kwarg_var is None:
+            extra.update(kwargs)
+            kwargs = {}
+
+        return (
+            new_args,
+            kwargs,
+            missing,
+            extra,
+            extra_positional,
+            arguments,
+            vararg_var,
+            kwarg_var,
+        )
+
+    _signature_cache[func] = parse
+    return parse
+
+
+def _date_to_unix(arg):
+    """Converts a timetuple, integer or datetime object into the seconds from
+    epoch in utc.
+    """
+    if isinstance(arg, datetime):
+        arg = arg.utctimetuple()
+    elif isinstance(arg, integer_types + (float,)):
+        return int(arg)
+    year, month, day, hour, minute, second = arg[:6]
+    days = date(year, month, 1).toordinal() - _epoch_ord + day - 1
+    hours = days * 24 + hour
+    minutes = hours * 60 + minute
+    seconds = minutes * 60 + second
+    return seconds
+
+
+class _DictAccessorProperty(object):
+    """Baseclass for `environ_property` and `header_property`."""
+
+    read_only = False
+
+    def __init__(
+        self,
+        name,
+        default=None,
+        load_func=None,
+        dump_func=None,
+        read_only=None,
+        doc=None,
+    ):
+        self.name = name
+        self.default = default
+        self.load_func = load_func
+        self.dump_func = dump_func
+        if read_only is not None:
+            self.read_only = read_only
+        self.__doc__ = doc
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+        storage = self.lookup(obj)
+        if self.name not in storage:
+            return self.default
+        rv = storage[self.name]
+        if self.load_func is not None:
+            try:
+                rv = self.load_func(rv)
+            except (ValueError, TypeError):
+                rv = self.default
+        return rv
+
+    def __set__(self, obj, value):
+        if self.read_only:
+            raise AttributeError("read only property")
+        if self.dump_func is not None:
+            value = self.dump_func(value)
+        self.lookup(obj)[self.name] = value
+
+    def __delete__(self, obj):
+        if self.read_only:
+            raise AttributeError("read only property")
+        self.lookup(obj).pop(self.name, None)
+
+    def __repr__(self):
+        return "<%s %s>" % (self.__class__.__name__, self.name)
+
+
+def _cookie_quote(b):
+    buf = bytearray()
+    all_legal = True
+    _lookup = _cookie_quoting_map.get
+    _push = buf.extend
+
+    for char in iter_bytes(b):
+        if char not in _legal_cookie_chars:
+            all_legal = False
+            char = _lookup(char, char)
+        _push(char)
+
+    if all_legal:
+        return bytes(buf)
+    return bytes(b'"' + buf + b'"')
+
+
+def _cookie_unquote(b):
+    if len(b) < 2:
+        return b
+    if b[:1] != b'"' or b[-1:] != b'"':
+        return b
+
+    b = b[1:-1]
+
+    i = 0
+    n = len(b)
+    rv = bytearray()
+    _push = rv.extend
+
+    while 0 <= i < n:
+        o_match = _octal_re.search(b, i)
+        q_match = _quote_re.search(b, i)
+        if not o_match and not q_match:
+            rv.extend(b[i:])
+            break
+        j = k = -1
+        if o_match:
+            j = o_match.start(0)
+        if q_match:
+            k = q_match.start(0)
+        if q_match and (not o_match or k < j):
+            _push(b[i:k])
+            _push(b[k + 1 : k + 2])
+            i = k + 2
+        else:
+            _push(b[i:j])
+            rv.append(int(b[j + 1 : j + 4], 8))
+            i = j + 4
+
+    return bytes(rv)
+
+
+def _cookie_parse_impl(b):
+    """Lowlevel cookie parsing facility that operates on bytes."""
+    i = 0
+    n = len(b)
+
+    while i < n:
+        match = _cookie_re.search(b + b";", i)
+        if not match:
+            break
+
+        key = match.group("key").strip()
+        value = match.group("val") or b""
+        i = match.end(0)
+
+        # Ignore parameters.  We have no interest in them.
+        if key.lower() not in _cookie_params:
+            yield _cookie_unquote(key), _cookie_unquote(value)
+
+
+def _encode_idna(domain):
+    # If we're given bytes, make sure they fit into ASCII
+    if not isinstance(domain, text_type):
+        domain.decode("ascii")
+        return domain
+
+    # Otherwise check if it's already ascii, then return
+    try:
+        return domain.encode("ascii")
+    except UnicodeError:
+        pass
+
+    # Otherwise encode each part separately
+    parts = domain.split(".")
+    for idx, part in enumerate(parts):
+        parts[idx] = part.encode("idna")
+    return b".".join(parts)
+
+
+def _decode_idna(domain):
+    # If the input is a string try to encode it to ascii to
+    # do the idna decoding.  if that fails because of an
+    # unicode error, then we already have a decoded idna domain
+    if isinstance(domain, text_type):
+        try:
+            domain = domain.encode("ascii")
+        except UnicodeError:
+            return domain
+
+    # Decode each part separately.  If a part fails, try to
+    # decode it with ascii and silently ignore errors.  This makes
+    # most sense because the idna codec does not have error handling
+    parts = domain.split(b".")
+    for idx, part in enumerate(parts):
+        try:
+            parts[idx] = part.decode("idna")
+        except UnicodeError:
+            parts[idx] = part.decode("ascii", "ignore")
+
+    return ".".join(parts)
+
+
+def _make_cookie_domain(domain):
+    if domain is None:
+        return None
+    domain = _encode_idna(domain)
+    if b":" in domain:
+        domain = domain.split(b":", 1)[0]
+    if b"." in domain:
+        return domain
+    raise ValueError(
+        "Setting 'domain' for a cookie on a server running locally (ex: "
+        "localhost) is not supported by complying browsers. You should "
+        "have something like: '127.0.0.1 localhost dev.localhost' on "
+        "your hosts file and then point your server to run on "
+        "'dev.localhost' and also set 'domain' for 'dev.localhost'"
+    )
+
+
+def _easteregg(app=None):
+    """Like the name says.  But who knows how it works?"""
+
+    def bzzzzzzz(gyver):
+        import base64
+        import zlib
+
+        return zlib.decompress(base64.b64decode(gyver)).decode("ascii")
+
+    gyver = u"\n".join(
+        [
+            x + (77 - len(x)) * u" "
+            for x in bzzzzzzz(
+                b"""
+eJyFlzuOJDkMRP06xRjymKgDJCDQStBYT8BCgK4gTwfQ2fcFs2a2FzvZk+hvlcRvRJD148efHt9m
+9Xz94dRY5hGt1nrYcXx7us9qlcP9HHNh28rz8dZj+q4rynVFFPdlY4zH873NKCexrDM6zxxRymzz
+4QIxzK4bth1PV7+uHn6WXZ5C4ka/+prFzx3zWLMHAVZb8RRUxtFXI5DTQ2n3Hi2sNI+HK43AOWSY
+jmEzE4naFp58PdzhPMdslLVWHTGUVpSxImw+pS/D+JhzLfdS1j7PzUMxij+mc2U0I9zcbZ/HcZxc
+q1QjvvcThMYFnp93agEx392ZdLJWXbi/Ca4Oivl4h/Y1ErEqP+lrg7Xa4qnUKu5UE9UUA4xeqLJ5
+jWlPKJvR2yhRI7xFPdzPuc6adXu6ovwXwRPXXnZHxlPtkSkqWHilsOrGrvcVWXgGP3daXomCj317
+8P2UOw/NnA0OOikZyFf3zZ76eN9QXNwYdD8f8/LdBRFg0BO3bB+Pe/+G8er8tDJv83XTkj7WeMBJ
+v/rnAfdO51d6sFglfi8U7zbnr0u9tyJHhFZNXYfH8Iafv2Oa+DT6l8u9UYlajV/hcEgk1x8E8L/r
+XJXl2SK+GJCxtnyhVKv6GFCEB1OO3f9YWAIEbwcRWv/6RPpsEzOkXURMN37J0PoCSYeBnJQd9Giu
+LxYQJNlYPSo/iTQwgaihbART7Fcyem2tTSCcwNCs85MOOpJtXhXDe0E7zgZJkcxWTar/zEjdIVCk
+iXy87FW6j5aGZhttDBoAZ3vnmlkx4q4mMmCdLtnHkBXFMCReqthSGkQ+MDXLLCpXwBs0t+sIhsDI
+tjBB8MwqYQpLygZ56rRHHpw+OAVyGgaGRHWy2QfXez+ZQQTTBkmRXdV/A9LwH6XGZpEAZU8rs4pE
+1R4FQ3Uwt8RKEtRc0/CrANUoes3EzM6WYcFyskGZ6UTHJWenBDS7h163Eo2bpzqxNE9aVgEM2CqI
+GAJe9Yra4P5qKmta27VjzYdR04Vc7KHeY4vs61C0nbywFmcSXYjzBHdiEjraS7PGG2jHHTpJUMxN
+Jlxr3pUuFvlBWLJGE3GcA1/1xxLcHmlO+LAXbhrXah1tD6Ze+uqFGdZa5FM+3eHcKNaEarutAQ0A
+QMAZHV+ve6LxAwWnXbbSXEG2DmCX5ijeLCKj5lhVFBrMm+ryOttCAeFpUdZyQLAQkA06RLs56rzG
+8MID55vqr/g64Qr/wqwlE0TVxgoiZhHrbY2h1iuuyUVg1nlkpDrQ7Vm1xIkI5XRKLedN9EjzVchu
+jQhXcVkjVdgP2O99QShpdvXWoSwkp5uMwyjt3jiWCqWGSiaaPAzohjPanXVLbM3x0dNskJsaCEyz
+DTKIs+7WKJD4ZcJGfMhLFBf6hlbnNkLEePF8Cx2o2kwmYF4+MzAxa6i+6xIQkswOqGO+3x9NaZX8
+MrZRaFZpLeVTYI9F/djY6DDVVs340nZGmwrDqTCiiqD5luj3OzwpmQCiQhdRYowUYEA3i1WWGwL4
+GCtSoO4XbIPFeKGU13XPkDf5IdimLpAvi2kVDVQbzOOa4KAXMFlpi/hV8F6IDe0Y2reg3PuNKT3i
+RYhZqtkQZqSB2Qm0SGtjAw7RDwaM1roESC8HWiPxkoOy0lLTRFG39kvbLZbU9gFKFRvixDZBJmpi
+Xyq3RE5lW00EJjaqwp/v3EByMSpVZYsEIJ4APaHmVtpGSieV5CALOtNUAzTBiw81GLgC0quyzf6c
+NlWknzJeCsJ5fup2R4d8CYGN77mu5vnO1UqbfElZ9E6cR6zbHjgsr9ly18fXjZoPeDjPuzlWbFwS
+pdvPkhntFvkc13qb9094LL5NrA3NIq3r9eNnop9DizWOqCEbyRBFJTHn6Tt3CG1o8a4HevYh0XiJ
+sR0AVVHuGuMOIfbuQ/OKBkGRC6NJ4u7sbPX8bG/n5sNIOQ6/Y/BX3IwRlTSabtZpYLB85lYtkkgm
+p1qXK3Du2mnr5INXmT/78KI12n11EFBkJHHp0wJyLe9MvPNUGYsf+170maayRoy2lURGHAIapSpQ
+krEDuNoJCHNlZYhKpvw4mspVWxqo415n8cD62N9+EfHrAvqQnINStetek7RY2Urv8nxsnGaZfRr/
+nhXbJ6m/yl1LzYqscDZA9QHLNbdaSTTr+kFg3bC0iYbX/eQy0Bv3h4B50/SGYzKAXkCeOLI3bcAt
+mj2Z/FM1vQWgDynsRwNvrWnJHlespkrp8+vO1jNaibm+PhqXPPv30YwDZ6jApe3wUjFQobghvW9p
+7f2zLkGNv8b191cD/3vs9Q833z8t"""
+            ).splitlines()
+        ]
+    )
+
+    def easteregged(environ, start_response):
+        def injecting_start_response(status, headers, exc_info=None):
+            headers.append(("X-Powered-By", "Werkzeug"))
+            return start_response(status, headers, exc_info)
+
+        if app is not None and environ.get("QUERY_STRING") != "macgybarchakku":
+            return app(environ, injecting_start_response)
+        injecting_start_response("200 OK", [("Content-Type", "text/html")])
+        return [
+            (
+                u"""
+<!DOCTYPE html>
+<html>
+<head>
+<title>About Werkzeug</title>
+<style type="text/css">
+  body { font: 15px Georgia, serif; text-align: center; }
+  a { color: #333; text-decoration: none; }
+  h1 { font-size: 30px; margin: 20px 0 10px 0; }
+  p { margin: 0 0 30px 0; }
+  pre { font: 11px 'Consolas', 'Monaco', monospace; line-height: 0.95; }
+</style>
+</head>
+<body>
+<h1><a href="http://werkzeug.pocoo.org/">Werkzeug</a></h1>
+<p>the Swiss Army knife of Python web development.</p>
+<pre>%s\n\n\n</pre>
+</body>
+</html>"""
+                % gyver
+            ).encode("latin1")
+        ]
+
+    return easteregged
diff --git a/python/werkzeug/_reloader.py b/python/werkzeug/_reloader.py
new file mode 100644
index 0000000..f06a63d
--- /dev/null
+++ b/python/werkzeug/_reloader.py
@@ -0,0 +1,334 @@
+import os
+import subprocess
+import sys
+import threading
+import time
+from itertools import chain
+
+from ._compat import iteritems
+from ._compat import PY2
+from ._compat import text_type
+from ._internal import _log
+
+
+def _iter_module_files():
+    """This iterates over all relevant Python files.  It goes through all
+    loaded files from modules, all files in folders of already loaded modules
+    as well as all files reachable through a package.
+    """
+    # The list call is necessary on Python 3 in case the module
+    # dictionary modifies during iteration.
+    for module in list(sys.modules.values()):
+        if module is None:
+            continue
+        filename = getattr(module, "__file__", None)
+        if filename:
+            if os.path.isdir(filename) and os.path.exists(
+                os.path.join(filename, "__init__.py")
+            ):
+                filename = os.path.join(filename, "__init__.py")
+
+            old = None
+            while not os.path.isfile(filename):
+                old = filename
+                filename = os.path.dirname(filename)
+                if filename == old:
+                    break
+            else:
+                if filename[-4:] in (".pyc", ".pyo"):
+                    filename = filename[:-1]
+                yield filename
+
+
+def _find_observable_paths(extra_files=None):
+    """Finds all paths that should be observed."""
+    rv = set(
+        os.path.dirname(os.path.abspath(x)) if os.path.isfile(x) else os.path.abspath(x)
+        for x in sys.path
+    )
+
+    for filename in extra_files or ():
+        rv.add(os.path.dirname(os.path.abspath(filename)))
+
+    for module in list(sys.modules.values()):
+        fn = getattr(module, "__file__", None)
+        if fn is None:
+            continue
+        fn = os.path.abspath(fn)
+        rv.add(os.path.dirname(fn))
+
+    return _find_common_roots(rv)
+
+
+def _get_args_for_reloading():
+    """Returns the executable. This contains a workaround for windows
+    if the executable is incorrectly reported to not have the .exe
+    extension which can cause bugs on reloading.  This also contains
+    a workaround for linux where the file is executable (possibly with
+    a program other than python)
+    """
+    rv = [sys.executable]
+    py_script = os.path.abspath(sys.argv[0])
+    args = sys.argv[1:]
+    # Need to look at main module to determine how it was executed.
+    __main__ = sys.modules["__main__"]
+
+    if __main__.__package__ is None:
+        # Executed a file, like "python app.py".
+        if os.name == "nt":
+            # Windows entry points have ".exe" extension and should be
+            # called directly.
+            if not os.path.exists(py_script) and os.path.exists(py_script + ".exe"):
+                py_script += ".exe"
+
+            if (
+                os.path.splitext(rv[0])[1] == ".exe"
+                and os.path.splitext(py_script)[1] == ".exe"
+            ):
+                rv.pop(0)
+
+        elif os.path.isfile(py_script) and os.access(py_script, os.X_OK):
+            # The file is marked as executable. Nix adds a wrapper that
+            # shouldn't be called with the Python executable.
+            rv.pop(0)
+
+        rv.append(py_script)
+    else:
+        # Executed a module, like "python -m werkzeug.serving".
+        if sys.argv[0] == "-m":
+            # Flask works around previous behavior by putting
+            # "-m flask" in sys.argv.
+            # TODO remove this once Flask no longer misbehaves
+            args = sys.argv
+        else:
+            py_module = __main__.__package__
+            name = os.path.splitext(os.path.basename(py_script))[0]
+
+            if name != "__main__":
+                py_module += "." + name
+
+            rv.extend(("-m", py_module.lstrip(".")))
+
+    rv.extend(args)
+    return rv
+
+
+def _find_common_roots(paths):
+    """Out of some paths it finds the common roots that need monitoring."""
+    paths = [x.split(os.path.sep) for x in paths]
+    root = {}
+    for chunks in sorted(paths, key=len, reverse=True):
+        node = root
+        for chunk in chunks:
+            node = node.setdefault(chunk, {})
+        node.clear()
+
+    rv = set()
+
+    def _walk(node, path):
+        for prefix, child in iteritems(node):
+            _walk(child, path + (prefix,))
+        if not node:
+            rv.add("/".join(path))
+
+    _walk(root, ())
+    return rv
+
+
+class ReloaderLoop(object):
+    name = None
+
+    # monkeypatched by testsuite. wrapping with `staticmethod` is required in
+    # case time.sleep has been replaced by a non-c function (e.g. by
+    # `eventlet.monkey_patch`) before we get here
+    _sleep = staticmethod(time.sleep)
+
+    def __init__(self, extra_files=None, interval=1):
+        self.extra_files = set(os.path.abspath(x) for x in extra_files or ())
+        self.interval = interval
+
+    def run(self):
+        pass
+
+    def restart_with_reloader(self):
+        """Spawn a new Python interpreter with the same arguments as this one,
+        but running the reloader thread.
+        """
+        while 1:
+            _log("info", " * Restarting with %s" % self.name)
+            args = _get_args_for_reloading()
+
+            # a weird bug on windows. sometimes unicode strings end up in the
+            # environment and subprocess.call does not like this, encode them
+            # to latin1 and continue.
+            if os.name == "nt" and PY2:
+                new_environ = {}
+                for key, value in iteritems(os.environ):
+                    if isinstance(key, text_type):
+                        key = key.encode("iso-8859-1")
+                    if isinstance(value, text_type):
+                        value = value.encode("iso-8859-1")
+                    new_environ[key] = value
+            else:
+                new_environ = os.environ.copy()
+
+            new_environ["WERKZEUG_RUN_MAIN"] = "true"
+            exit_code = subprocess.call(args, env=new_environ, close_fds=False)
+            if exit_code != 3:
+                return exit_code
+
+    def trigger_reload(self, filename):
+        self.log_reload(filename)
+        sys.exit(3)
+
+    def log_reload(self, filename):
+        filename = os.path.abspath(filename)
+        _log("info", " * Detected change in %r, reloading" % filename)
+
+
+class StatReloaderLoop(ReloaderLoop):
+    name = "stat"
+
+    def run(self):
+        mtimes = {}
+        while 1:
+            for filename in chain(_iter_module_files(), self.extra_files):
+                try:
+                    mtime = os.stat(filename).st_mtime
+                except OSError:
+                    continue
+
+                old_time = mtimes.get(filename)
+                if old_time is None:
+                    mtimes[filename] = mtime
+                    continue
+                elif mtime > old_time:
+                    self.trigger_reload(filename)
+            self._sleep(self.interval)
+
+
+class WatchdogReloaderLoop(ReloaderLoop):
+    def __init__(self, *args, **kwargs):
+        ReloaderLoop.__init__(self, *args, **kwargs)
+        from watchdog.observers import Observer
+        from watchdog.events import FileSystemEventHandler
+
+        self.observable_paths = set()
+
+        def _check_modification(filename):
+            if filename in self.extra_files:
+                self.trigger_reload(filename)
+            dirname = os.path.dirname(filename)
+            if dirname.startswith(tuple(self.observable_paths)):
+                if filename.endswith((".pyc", ".pyo", ".py")):
+                    self.trigger_reload(filename)
+
+        class _CustomHandler(FileSystemEventHandler):
+            def on_created(self, event):
+                _check_modification(event.src_path)
+
+            def on_modified(self, event):
+                _check_modification(event.src_path)
+
+            def on_moved(self, event):
+                _check_modification(event.src_path)
+                _check_modification(event.dest_path)
+
+            def on_deleted(self, event):
+                _check_modification(event.src_path)
+
+        reloader_name = Observer.__name__.lower()
+        if reloader_name.endswith("observer"):
+            reloader_name = reloader_name[:-8]
+        reloader_name += " reloader"
+
+        self.name = reloader_name
+
+        self.observer_class = Observer
+        self.event_handler = _CustomHandler()
+        self.should_reload = False
+
+    def trigger_reload(self, filename):
+        # This is called inside an event handler, which means throwing
+        # SystemExit has no effect.
+        # https://github.com/gorakhargosh/watchdog/issues/294
+        self.should_reload = True
+        self.log_reload(filename)
+
+    def run(self):
+        watches = {}
+        observer = self.observer_class()
+        observer.start()
+
+        try:
+            while not self.should_reload:
+                to_delete = set(watches)
+                paths = _find_observable_paths(self.extra_files)
+                for path in paths:
+                    if path not in watches:
+                        try:
+                            watches[path] = observer.schedule(
+                                self.event_handler, path, recursive=True
+                            )
+                        except OSError:
+                            # Clear this path from list of watches We don't want
+                            # the same error message showing again in the next
+                            # iteration.
+                            watches[path] = None
+                    to_delete.discard(path)
+                for path in to_delete:
+                    watch = watches.pop(path, None)
+                    if watch is not None:
+                        observer.unschedule(watch)
+                self.observable_paths = paths
+                self._sleep(self.interval)
+        finally:
+            observer.stop()
+            observer.join()
+
+        sys.exit(3)
+
+
+reloader_loops = {"stat": StatReloaderLoop, "watchdog": WatchdogReloaderLoop}
+
+try:
+    __import__("watchdog.observers")
+except ImportError:
+    reloader_loops["auto"] = reloader_loops["stat"]
+else:
+    reloader_loops["auto"] = reloader_loops["watchdog"]
+
+
+def ensure_echo_on():
+    """Ensure that echo mode is enabled. Some tools such as PDB disable
+    it which causes usability issues after reload."""
+    # tcgetattr will fail if stdin isn't a tty
+    if not sys.stdin.isatty():
+        return
+    try:
+        import termios
+    except ImportError:
+        return
+    attributes = termios.tcgetattr(sys.stdin)
+    if not attributes[3] & termios.ECHO:
+        attributes[3] |= termios.ECHO
+        termios.tcsetattr(sys.stdin, termios.TCSANOW, attributes)
+
+
+def run_with_reloader(main_func, extra_files=None, interval=1, reloader_type="auto"):
+    """Run the given function in an independent python interpreter."""
+    import signal
+
+    reloader = reloader_loops[reloader_type](extra_files, interval)
+    signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
+    try:
+        if os.environ.get("WERKZEUG_RUN_MAIN") == "true":
+            ensure_echo_on()
+            t = threading.Thread(target=main_func, args=())
+            t.setDaemon(True)
+            t.start()
+            reloader.run()
+        else:
+            sys.exit(reloader.restart_with_reloader())
+    except KeyboardInterrupt:
+        pass
diff --git a/python/werkzeug/contrib/__init__.py b/python/werkzeug/contrib/__init__.py
new file mode 100644
index 0000000..0e741f0
--- /dev/null
+++ b/python/werkzeug/contrib/__init__.py
@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.contrib
+    ~~~~~~~~~~~~~~~~
+
+    Contains user-submitted code that other users may find useful, but which
+    is not part of the Werkzeug core.  Anyone can write code for inclusion in
+    the `contrib` package.  All modules in this package are distributed as an
+    add-on library and thus are not part of Werkzeug itself.
+
+    This file itself is mostly for informational purposes and to tell the
+    Python interpreter that `contrib` is a package.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
diff --git a/python/werkzeug/contrib/atom.py b/python/werkzeug/contrib/atom.py
new file mode 100644
index 0000000..d079d2b
--- /dev/null
+++ b/python/werkzeug/contrib/atom.py
@@ -0,0 +1,362 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.contrib.atom
+    ~~~~~~~~~~~~~~~~~~~~~
+
+    This module provides a class called :class:`AtomFeed` which can be
+    used to generate feeds in the Atom syndication format (see :rfc:`4287`).
+
+    Example::
+
+        def atom_feed(request):
+            feed = AtomFeed("My Blog", feed_url=request.url,
+                            url=request.host_url,
+                            subtitle="My example blog for a feed test.")
+            for post in Post.query.limit(10).all():
+                feed.add(post.title, post.body, content_type='html',
+                         author=post.author, url=post.url, id=post.uid,
+                         updated=post.last_update, published=post.pub_date)
+            return feed.get_response()
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import warnings
+from datetime import datetime
+
+from .._compat import implements_to_string
+from .._compat import string_types
+from ..utils import escape
+from ..wrappers import BaseResponse
+
+warnings.warn(
+    "'werkzeug.contrib.atom' is deprecated as of version 0.15 and will"
+    " be removed in version 1.0.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+XHTML_NAMESPACE = "http://www.w3.org/1999/xhtml"
+
+
+def _make_text_block(name, content, content_type=None):
+    """Helper function for the builder that creates an XML text block."""
+    if content_type == "xhtml":
+        return u'<%s type="xhtml"><div xmlns="%s">%s</div></%s>\n' % (
+            name,
+            XHTML_NAMESPACE,
+            content,
+            name,
+        )
+    if not content_type:
+        return u"<%s>%s</%s>\n" % (name, escape(content), name)
+    return u'<%s type="%s">%s</%s>\n' % (name, content_type, escape(content), name)
+
+
+def format_iso8601(obj):
+    """Format a datetime object for iso8601"""
+    iso8601 = obj.isoformat()
+    if obj.tzinfo:
+        return iso8601
+    return iso8601 + "Z"
+
+
+@implements_to_string
+class AtomFeed(object):
+
+    """A helper class that creates Atom feeds.
+
+    :param title: the title of the feed. Required.
+    :param title_type: the type attribute for the title element.  One of
+                       ``'html'``, ``'text'`` or ``'xhtml'``.
+    :param url: the url for the feed (not the url *of* the feed)
+    :param id: a globally unique id for the feed.  Must be an URI.  If
+               not present the `feed_url` is used, but one of both is
+               required.
+    :param updated: the time the feed was modified the last time.  Must
+                    be a :class:`datetime.datetime` object.  If not
+                    present the latest entry's `updated` is used.
+                    Treated as UTC if naive datetime.
+    :param feed_url: the URL to the feed.  Should be the URL that was
+                     requested.
+    :param author: the author of the feed.  Must be either a string (the
+                   name) or a dict with name (required) and uri or
+                   email (both optional).  Can be a list of (may be
+                   mixed, too) strings and dicts, too, if there are
+                   multiple authors. Required if not every entry has an
+                   author element.
+    :param icon: an icon for the feed.
+    :param logo: a logo for the feed.
+    :param rights: copyright information for the feed.
+    :param rights_type: the type attribute for the rights element.  One of
+                        ``'html'``, ``'text'`` or ``'xhtml'``.  Default is
+                        ``'text'``.
+    :param subtitle: a short description of the feed.
+    :param subtitle_type: the type attribute for the subtitle element.
+                          One of ``'text'``, ``'html'``, ``'text'``
+                          or ``'xhtml'``.  Default is ``'text'``.
+    :param links: additional links.  Must be a list of dictionaries with
+                  href (required) and rel, type, hreflang, title, length
+                  (all optional)
+    :param generator: the software that generated this feed.  This must be
+                      a tuple in the form ``(name, url, version)``.  If
+                      you don't want to specify one of them, set the item
+                      to `None`.
+    :param entries: a list with the entries for the feed. Entries can also
+                    be added later with :meth:`add`.
+
+    For more information on the elements see
+    http://www.atomenabled.org/developers/syndication/
+
+    Everywhere where a list is demanded, any iterable can be used.
+    """
+
+    default_generator = ("Werkzeug", None, None)
+
+    def __init__(self, title=None, entries=None, **kwargs):
+        self.title = title
+        self.title_type = kwargs.get("title_type", "text")
+        self.url = kwargs.get("url")
+        self.feed_url = kwargs.get("feed_url", self.url)
+        self.id = kwargs.get("id", self.feed_url)
+        self.updated = kwargs.get("updated")
+        self.author = kwargs.get("author", ())
+        self.icon = kwargs.get("icon")
+        self.logo = kwargs.get("logo")
+        self.rights = kwargs.get("rights")
+        self.rights_type = kwargs.get("rights_type")
+        self.subtitle = kwargs.get("subtitle")
+        self.subtitle_type = kwargs.get("subtitle_type", "text")
+        self.generator = kwargs.get("generator")
+        if self.generator is None:
+            self.generator = self.default_generator
+        self.links = kwargs.get("links", [])
+        self.entries = list(entries) if entries else []
+
+        if not hasattr(self.author, "__iter__") or isinstance(
+            self.author, string_types + (dict,)
+        ):
+            self.author = [self.author]
+        for i, author in enumerate(self.author):
+            if not isinstance(author, dict):
+                self.author[i] = {"name": author}
+
+        if not self.title:
+            raise ValueError("title is required")
+        if not self.id:
+            raise ValueError("id is required")
+        for author in self.author:
+            if "name" not in author:
+                raise TypeError("author must contain at least a name")
+
+    def add(self, *args, **kwargs):
+        """Add a new entry to the feed.  This function can either be called
+        with a :class:`FeedEntry` or some keyword and positional arguments
+        that are forwarded to the :class:`FeedEntry` constructor.
+        """
+        if len(args) == 1 and not kwargs and isinstance(args[0], FeedEntry):
+            self.entries.append(args[0])
+        else:
+            kwargs["feed_url"] = self.feed_url
+            self.entries.append(FeedEntry(*args, **kwargs))
+
+    def __repr__(self):
+        return "<%s %r (%d entries)>" % (
+            self.__class__.__name__,
+            self.title,
+            len(self.entries),
+        )
+
+    def generate(self):
+        """Return a generator that yields pieces of XML."""
+        # atom demands either an author element in every entry or a global one
+        if not self.author:
+            if any(not e.author for e in self.entries):
+                self.author = ({"name": "Unknown author"},)
+
+        if not self.updated:
+            dates = sorted([entry.updated for entry in self.entries])
+            self.updated = dates[-1] if dates else datetime.utcnow()
+
+        yield u'<?xml version="1.0" encoding="utf-8"?>\n'
+        yield u'<feed xmlns="http://www.w3.org/2005/Atom">\n'
+        yield "  " + _make_text_block("title", self.title, self.title_type)
+        yield u"  <id>%s</id>\n" % escape(self.id)
+        yield u"  <updated>%s</updated>\n" % format_iso8601(self.updated)
+        if self.url:
+            yield u'  <link href="%s" />\n' % escape(self.url)
+        if self.feed_url:
+            yield u'  <link href="%s" rel="self" />\n' % escape(self.feed_url)
+        for link in self.links:
+            yield u"  <link %s/>\n" % "".join(
+                '%s="%s" ' % (k, escape(link[k])) for k in link
+            )
+        for author in self.author:
+            yield u"  <author>\n"
+            yield u"    <name>%s</name>\n" % escape(author["name"])
+            if "uri" in author:
+                yield u"    <uri>%s</uri>\n" % escape(author["uri"])
+            if "email" in author:
+                yield "    <email>%s</email>\n" % escape(author["email"])
+            yield "  </author>\n"
+        if self.subtitle:
+            yield "  " + _make_text_block("subtitle", self.subtitle, self.subtitle_type)
+        if self.icon:
+            yield u"  <icon>%s</icon>\n" % escape(self.icon)
+        if self.logo:
+            yield u"  <logo>%s</logo>\n" % escape(self.logo)
+        if self.rights:
+            yield "  " + _make_text_block("rights", self.rights, self.rights_type)
+        generator_name, generator_url, generator_version = self.generator
+        if generator_name or generator_url or generator_version:
+            tmp = [u"  <generator"]
+            if generator_url:
+                tmp.append(u' uri="%s"' % escape(generator_url))
+            if generator_version:
+                tmp.append(u' version="%s"' % escape(generator_version))
+            tmp.append(u">%s</generator>\n" % escape(generator_name))
+            yield u"".join(tmp)
+        for entry in self.entries:
+            for line in entry.generate():
+                yield u"  " + line
+        yield u"</feed>\n"
+
+    def to_string(self):
+        """Convert the feed into a string."""
+        return u"".join(self.generate())
+
+    def get_response(self):
+        """Return a response object for the feed."""
+        return BaseResponse(self.to_string(), mimetype="application/atom+xml")
+
+    def __call__(self, environ, start_response):
+        """Use the class as WSGI response object."""
+        return self.get_response()(environ, start_response)
+
+    def __str__(self):
+        return self.to_string()
+
+
+@implements_to_string
+class FeedEntry(object):
+
+    """Represents a single entry in a feed.
+
+    :param title: the title of the entry. Required.
+    :param title_type: the type attribute for the title element.  One of
+                       ``'html'``, ``'text'`` or ``'xhtml'``.
+    :param content: the content of the entry.
+    :param content_type: the type attribute for the content element.  One
+                         of ``'html'``, ``'text'`` or ``'xhtml'``.
+    :param summary: a summary of the entry's content.
+    :param summary_type: the type attribute for the summary element.  One
+                         of ``'html'``, ``'text'`` or ``'xhtml'``.
+    :param url: the url for the entry.
+    :param id: a globally unique id for the entry.  Must be an URI.  If
+               not present the URL is used, but one of both is required.
+    :param updated: the time the entry was modified the last time.  Must
+                    be a :class:`datetime.datetime` object.  Treated as
+                    UTC if naive datetime. Required.
+    :param author: the author of the entry.  Must be either a string (the
+                   name) or a dict with name (required) and uri or
+                   email (both optional).  Can be a list of (may be
+                   mixed, too) strings and dicts, too, if there are
+                   multiple authors. Required if the feed does not have an
+                   author element.
+    :param published: the time the entry was initially published.  Must
+                      be a :class:`datetime.datetime` object.  Treated as
+                      UTC if naive datetime.
+    :param rights: copyright information for the entry.
+    :param rights_type: the type attribute for the rights element.  One of
+                        ``'html'``, ``'text'`` or ``'xhtml'``.  Default is
+                        ``'text'``.
+    :param links: additional links.  Must be a list of dictionaries with
+                  href (required) and rel, type, hreflang, title, length
+                  (all optional)
+    :param categories: categories for the entry. Must be a list of dictionaries
+                       with term (required), scheme and label (all optional)
+    :param xml_base: The xml base (url) for this feed item.  If not provided
+                     it will default to the item url.
+
+    For more information on the elements see
+    http://www.atomenabled.org/developers/syndication/
+
+    Everywhere where a list is demanded, any iterable can be used.
+    """
+
+    def __init__(self, title=None, content=None, feed_url=None, **kwargs):
+        self.title = title
+        self.title_type = kwargs.get("title_type", "text")
+        self.content = content
+        self.content_type = kwargs.get("content_type", "html")
+        self.url = kwargs.get("url")
+        self.id = kwargs.get("id", self.url)
+        self.updated = kwargs.get("updated")
+        self.summary = kwargs.get("summary")
+        self.summary_type = kwargs.get("summary_type", "html")
+        self.author = kwargs.get("author", ())
+        self.published = kwargs.get("published")
+        self.rights = kwargs.get("rights")
+        self.links = kwargs.get("links", [])
+        self.categories = kwargs.get("categories", [])
+        self.xml_base = kwargs.get("xml_base", feed_url)
+
+        if not hasattr(self.author, "__iter__") or isinstance(
+            self.author, string_types + (dict,)
+        ):
+            self.author = [self.author]
+        for i, author in enumerate(self.author):
+            if not isinstance(author, dict):
+                self.author[i] = {"name": author}
+
+        if not self.title:
+            raise ValueError("title is required")
+        if not self.id:
+            raise ValueError("id is required")
+        if not self.updated:
+            raise ValueError("updated is required")
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, self.title)
+
+    def generate(self):
+        """Yields pieces of ATOM XML."""
+        base = ""
+        if self.xml_base:
+            base = ' xml:base="%s"' % escape(self.xml_base)
+        yield u"<entry%s>\n" % base
+        yield u"  " + _make_text_block("title", self.title, self.title_type)
+        yield u"  <id>%s</id>\n" % escape(self.id)
+        yield u"  <updated>%s</updated>\n" % format_iso8601(self.updated)
+        if self.published:
+            yield u"  <published>%s</published>\n" % format_iso8601(self.published)
+        if self.url:
+            yield u'  <link href="%s" />\n' % escape(self.url)
+        for author in self.author:
+            yield u"  <author>\n"
+            yield u"    <name>%s</name>\n" % escape(author["name"])
+            if "uri" in author:
+                yield u"    <uri>%s</uri>\n" % escape(author["uri"])
+            if "email" in author:
+                yield u"    <email>%s</email>\n" % escape(author["email"])
+            yield u"  </author>\n"
+        for link in self.links:
+            yield u"  <link %s/>\n" % "".join(
+                '%s="%s" ' % (k, escape(link[k])) for k in link
+            )
+        for category in self.categories:
+            yield u"  <category %s/>\n" % "".join(
+                '%s="%s" ' % (k, escape(category[k])) for k in category
+            )
+        if self.summary:
+            yield u"  " + _make_text_block("summary", self.summary, self.summary_type)
+        if self.content:
+            yield u"  " + _make_text_block("content", self.content, self.content_type)
+        yield u"</entry>\n"
+
+    def to_string(self):
+        """Convert the feed item into a unicode object."""
+        return u"".join(self.generate())
+
+    def __str__(self):
+        return self.to_string()
diff --git a/python/werkzeug/contrib/cache.py b/python/werkzeug/contrib/cache.py
new file mode 100644
index 0000000..79c749b
--- /dev/null
+++ b/python/werkzeug/contrib/cache.py
@@ -0,0 +1,933 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.contrib.cache
+    ~~~~~~~~~~~~~~~~~~~~~~
+
+    The main problem with dynamic Web sites is, well, they're dynamic.  Each
+    time a user requests a page, the webserver executes a lot of code, queries
+    the database, renders templates until the visitor gets the page he sees.
+
+    This is a lot more expensive than just loading a file from the file system
+    and sending it to the visitor.
+
+    For most Web applications, this overhead isn't a big deal but once it
+    becomes, you will be glad to have a cache system in place.
+
+    How Caching Works
+    =================
+
+    Caching is pretty simple.  Basically you have a cache object lurking around
+    somewhere that is connected to a remote cache or the file system or
+    something else.  When the request comes in you check if the current page
+    is already in the cache and if so, you're returning it from the cache.
+    Otherwise you generate the page and put it into the cache. (Or a fragment
+    of the page, you don't have to cache the full thing)
+
+    Here is a simple example of how to cache a sidebar for 5 minutes::
+
+        def get_sidebar(user):
+            identifier = 'sidebar_for/user%d' % user.id
+            value = cache.get(identifier)
+            if value is not None:
+                return value
+            value = generate_sidebar_for(user=user)
+            cache.set(identifier, value, timeout=60 * 5)
+            return value
+
+    Creating a Cache Object
+    =======================
+
+    To create a cache object you just import the cache system of your choice
+    from the cache module and instantiate it.  Then you can start working
+    with that object:
+
+    >>> from werkzeug.contrib.cache import SimpleCache
+    >>> c = SimpleCache()
+    >>> c.set("foo", "value")
+    >>> c.get("foo")
+    'value'
+    >>> c.get("missing") is None
+    True
+
+    Please keep in mind that you have to create the cache and put it somewhere
+    you have access to it (either as a module global you can import or you just
+    put it into your WSGI application).
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import errno
+import os
+import platform
+import re
+import tempfile
+import warnings
+from hashlib import md5
+from time import time
+
+from .._compat import integer_types
+from .._compat import iteritems
+from .._compat import string_types
+from .._compat import text_type
+from .._compat import to_native
+from ..posixemulation import rename
+
+try:
+    import cPickle as pickle
+except ImportError:  # pragma: no cover
+    import pickle
+
+warnings.warn(
+    "'werkzeug.contrib.cache' is deprecated as of version 0.15 and will"
+    " be removed in version 1.0. It has moved to https://github.com"
+    "/pallets/cachelib.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+
+def _items(mappingorseq):
+    """Wrapper for efficient iteration over mappings represented by dicts
+    or sequences::
+
+        >>> for k, v in _items((i, i*i) for i in xrange(5)):
+        ...    assert k*k == v
+
+        >>> for k, v in _items(dict((i, i*i) for i in xrange(5))):
+        ...    assert k*k == v
+
+    """
+    if hasattr(mappingorseq, "items"):
+        return iteritems(mappingorseq)
+    return mappingorseq
+
+
+class BaseCache(object):
+    """Baseclass for the cache systems.  All the cache systems implement this
+    API or a superset of it.
+
+    :param default_timeout: the default timeout (in seconds) that is used if
+                            no timeout is specified on :meth:`set`. A timeout
+                            of 0 indicates that the cache never expires.
+    """
+
+    def __init__(self, default_timeout=300):
+        self.default_timeout = default_timeout
+
+    def _normalize_timeout(self, timeout):
+        if timeout is None:
+            timeout = self.default_timeout
+        return timeout
+
+    def get(self, key):
+        """Look up key in the cache and return the value for it.
+
+        :param key: the key to be looked up.
+        :returns: The value if it exists and is readable, else ``None``.
+        """
+        return None
+
+    def delete(self, key):
+        """Delete `key` from the cache.
+
+        :param key: the key to delete.
+        :returns: Whether the key existed and has been deleted.
+        :rtype: boolean
+        """
+        return True
+
+    def get_many(self, *keys):
+        """Returns a list of values for the given keys.
+        For each key an item in the list is created::
+
+            foo, bar = cache.get_many("foo", "bar")
+
+        Has the same error handling as :meth:`get`.
+
+        :param keys: The function accepts multiple keys as positional
+                     arguments.
+        """
+        return [self.get(k) for k in keys]
+
+    def get_dict(self, *keys):
+        """Like :meth:`get_many` but return a dict::
+
+            d = cache.get_dict("foo", "bar")
+            foo = d["foo"]
+            bar = d["bar"]
+
+        :param keys: The function accepts multiple keys as positional
+                     arguments.
+        """
+        return dict(zip(keys, self.get_many(*keys)))
+
+    def set(self, key, value, timeout=None):
+        """Add a new key/value to the cache (overwrites value, if key already
+        exists in the cache).
+
+        :param key: the key to set
+        :param value: the value for the key
+        :param timeout: the cache timeout for the key in seconds (if not
+                        specified, it uses the default timeout). A timeout of
+                        0 idicates that the cache never expires.
+        :returns: ``True`` if key has been updated, ``False`` for backend
+                  errors. Pickling errors, however, will raise a subclass of
+                  ``pickle.PickleError``.
+        :rtype: boolean
+        """
+        return True
+
+    def add(self, key, value, timeout=None):
+        """Works like :meth:`set` but does not overwrite the values of already
+        existing keys.
+
+        :param key: the key to set
+        :param value: the value for the key
+        :param timeout: the cache timeout for the key in seconds (if not
+                        specified, it uses the default timeout). A timeout of
+                        0 idicates that the cache never expires.
+        :returns: Same as :meth:`set`, but also ``False`` for already
+                  existing keys.
+        :rtype: boolean
+        """
+        return True
+
+    def set_many(self, mapping, timeout=None):
+        """Sets multiple keys and values from a mapping.
+
+        :param mapping: a mapping with the keys/values to set.
+        :param timeout: the cache timeout for the key in seconds (if not
+                        specified, it uses the default timeout). A timeout of
+                        0 idicates that the cache never expires.
+        :returns: Whether all given keys have been set.
+        :rtype: boolean
+        """
+        rv = True
+        for key, value in _items(mapping):
+            if not self.set(key, value, timeout):
+                rv = False
+        return rv
+
+    def delete_many(self, *keys):
+        """Deletes multiple keys at once.
+
+        :param keys: The function accepts multiple keys as positional
+                     arguments.
+        :returns: Whether all given keys have been deleted.
+        :rtype: boolean
+        """
+        return all(self.delete(key) for key in keys)
+
+    def has(self, key):
+        """Checks if a key exists in the cache without returning it. This is a
+        cheap operation that bypasses loading the actual data on the backend.
+
+        This method is optional and may not be implemented on all caches.
+
+        :param key: the key to check
+        """
+        raise NotImplementedError(
+            "%s doesn't have an efficient implementation of `has`. That "
+            "means it is impossible to check whether a key exists without "
+            "fully loading the key's data. Consider using `self.get` "
+            "explicitly if you don't care about performance."
+        )
+
+    def clear(self):
+        """Clears the cache.  Keep in mind that not all caches support
+        completely clearing the cache.
+
+        :returns: Whether the cache has been cleared.
+        :rtype: boolean
+        """
+        return True
+
+    def inc(self, key, delta=1):
+        """Increments the value of a key by `delta`.  If the key does
+        not yet exist it is initialized with `delta`.
+
+        For supporting caches this is an atomic operation.
+
+        :param key: the key to increment.
+        :param delta: the delta to add.
+        :returns: The new value or ``None`` for backend errors.
+        """
+        value = (self.get(key) or 0) + delta
+        return value if self.set(key, value) else None
+
+    def dec(self, key, delta=1):
+        """Decrements the value of a key by `delta`.  If the key does
+        not yet exist it is initialized with `-delta`.
+
+        For supporting caches this is an atomic operation.
+
+        :param key: the key to increment.
+        :param delta: the delta to subtract.
+        :returns: The new value or `None` for backend errors.
+        """
+        value = (self.get(key) or 0) - delta
+        return value if self.set(key, value) else None
+
+
+class NullCache(BaseCache):
+    """A cache that doesn't cache.  This can be useful for unit testing.
+
+    :param default_timeout: a dummy parameter that is ignored but exists
+                            for API compatibility with other caches.
+    """
+
+    def has(self, key):
+        return False
+
+
+class SimpleCache(BaseCache):
+    """Simple memory cache for single process environments.  This class exists
+    mainly for the development server and is not 100% thread safe.  It tries
+    to use as many atomic operations as possible and no locks for simplicity
+    but it could happen under heavy load that keys are added multiple times.
+
+    :param threshold: the maximum number of items the cache stores before
+                      it starts deleting some.
+    :param default_timeout: the default timeout that is used if no timeout is
+                            specified on :meth:`~BaseCache.set`. A timeout of
+                            0 indicates that the cache never expires.
+    """
+
+    def __init__(self, threshold=500, default_timeout=300):
+        BaseCache.__init__(self, default_timeout)
+        self._cache = {}
+        self.clear = self._cache.clear
+        self._threshold = threshold
+
+    def _prune(self):
+        if len(self._cache) > self._threshold:
+            now = time()
+            toremove = []
+            for idx, (key, (expires, _)) in enumerate(self._cache.items()):
+                if (expires != 0 and expires <= now) or idx % 3 == 0:
+                    toremove.append(key)
+            for key in toremove:
+                self._cache.pop(key, None)
+
+    def _normalize_timeout(self, timeout):
+        timeout = BaseCache._normalize_timeout(self, timeout)
+        if timeout > 0:
+            timeout = time() + timeout
+        return timeout
+
+    def get(self, key):
+        try:
+            expires, value = self._cache[key]
+            if expires == 0 or expires > time():
+                return pickle.loads(value)
+        except (KeyError, pickle.PickleError):
+            return None
+
+    def set(self, key, value, timeout=None):
+        expires = self._normalize_timeout(timeout)
+        self._prune()
+        self._cache[key] = (expires, pickle.dumps(value, pickle.HIGHEST_PROTOCOL))
+        return True
+
+    def add(self, key, value, timeout=None):
+        expires = self._normalize_timeout(timeout)
+        self._prune()
+        item = (expires, pickle.dumps(value, pickle.HIGHEST_PROTOCOL))
+        if key in self._cache:
+            return False
+        self._cache.setdefault(key, item)
+        return True
+
+    def delete(self, key):
+        return self._cache.pop(key, None) is not None
+
+    def has(self, key):
+        try:
+            expires, value = self._cache[key]
+            return expires == 0 or expires > time()
+        except KeyError:
+            return False
+
+
+_test_memcached_key = re.compile(r"[^\x00-\x21\xff]{1,250}$").match
+
+
+class MemcachedCache(BaseCache):
+    """A cache that uses memcached as backend.
+
+    The first argument can either be an object that resembles the API of a
+    :class:`memcache.Client` or a tuple/list of server addresses. In the
+    event that a tuple/list is passed, Werkzeug tries to import the best
+    available memcache library.
+
+    This cache looks into the following packages/modules to find bindings for
+    memcached:
+
+        - ``pylibmc``
+        - ``google.appengine.api.memcached``
+        - ``memcached``
+        - ``libmc``
+
+    Implementation notes:  This cache backend works around some limitations in
+    memcached to simplify the interface.  For example unicode keys are encoded
+    to utf-8 on the fly.  Methods such as :meth:`~BaseCache.get_dict` return
+    the keys in the same format as passed.  Furthermore all get methods
+    silently ignore key errors to not cause problems when untrusted user data
+    is passed to the get methods which is often the case in web applications.
+
+    :param servers: a list or tuple of server addresses or alternatively
+                    a :class:`memcache.Client` or a compatible client.
+    :param default_timeout: the default timeout that is used if no timeout is
+                            specified on :meth:`~BaseCache.set`. A timeout of
+                            0 indicates that the cache never expires.
+    :param key_prefix: a prefix that is added before all keys.  This makes it
+                       possible to use the same memcached server for different
+                       applications.  Keep in mind that
+                       :meth:`~BaseCache.clear` will also clear keys with a
+                       different prefix.
+    """
+
+    def __init__(self, servers=None, default_timeout=300, key_prefix=None):
+        BaseCache.__init__(self, default_timeout)
+        if servers is None or isinstance(servers, (list, tuple)):
+            if servers is None:
+                servers = ["127.0.0.1:11211"]
+            self._client = self.import_preferred_memcache_lib(servers)
+            if self._client is None:
+                raise RuntimeError("no memcache module found")
+        else:
+            # NOTE: servers is actually an already initialized memcache
+            # client.
+            self._client = servers
+
+        self.key_prefix = to_native(key_prefix)
+
+    def _normalize_key(self, key):
+        key = to_native(key, "utf-8")
+        if self.key_prefix:
+            key = self.key_prefix + key
+        return key
+
+    def _normalize_timeout(self, timeout):
+        timeout = BaseCache._normalize_timeout(self, timeout)
+        if timeout > 0:
+            timeout = int(time()) + timeout
+        return timeout
+
+    def get(self, key):
+        key = self._normalize_key(key)
+        # memcached doesn't support keys longer than that.  Because often
+        # checks for so long keys can occur because it's tested from user
+        # submitted data etc we fail silently for getting.
+        if _test_memcached_key(key):
+            return self._client.get(key)
+
+    def get_dict(self, *keys):
+        key_mapping = {}
+        have_encoded_keys = False
+        for key in keys:
+            encoded_key = self._normalize_key(key)
+            if not isinstance(key, str):
+                have_encoded_keys = True
+            if _test_memcached_key(key):
+                key_mapping[encoded_key] = key
+        _keys = list(key_mapping)
+        d = rv = self._client.get_multi(_keys)
+        if have_encoded_keys or self.key_prefix:
+            rv = {}
+            for key, value in iteritems(d):
+                rv[key_mapping[key]] = value
+        if len(rv) < len(keys):
+            for key in keys:
+                if key not in rv:
+                    rv[key] = None
+        return rv
+
+    def add(self, key, value, timeout=None):
+        key = self._normalize_key(key)
+        timeout = self._normalize_timeout(timeout)
+        return self._client.add(key, value, timeout)
+
+    def set(self, key, value, timeout=None):
+        key = self._normalize_key(key)
+        timeout = self._normalize_timeout(timeout)
+        return self._client.set(key, value, timeout)
+
+    def get_many(self, *keys):
+        d = self.get_dict(*keys)
+        return [d[key] for key in keys]
+
+    def set_many(self, mapping, timeout=None):
+        new_mapping = {}
+        for key, value in _items(mapping):
+            key = self._normalize_key(key)
+            new_mapping[key] = value
+
+        timeout = self._normalize_timeout(timeout)
+        failed_keys = self._client.set_multi(new_mapping, timeout)
+        return not failed_keys
+
+    def delete(self, key):
+        key = self._normalize_key(key)
+        if _test_memcached_key(key):
+            return self._client.delete(key)
+
+    def delete_many(self, *keys):
+        new_keys = []
+        for key in keys:
+            key = self._normalize_key(key)
+            if _test_memcached_key(key):
+                new_keys.append(key)
+        return self._client.delete_multi(new_keys)
+
+    def has(self, key):
+        key = self._normalize_key(key)
+        if _test_memcached_key(key):
+            return self._client.append(key, "")
+        return False
+
+    def clear(self):
+        return self._client.flush_all()
+
+    def inc(self, key, delta=1):
+        key = self._normalize_key(key)
+        return self._client.incr(key, delta)
+
+    def dec(self, key, delta=1):
+        key = self._normalize_key(key)
+        return self._client.decr(key, delta)
+
+    def import_preferred_memcache_lib(self, servers):
+        """Returns an initialized memcache client.  Used by the constructor."""
+        try:
+            import pylibmc
+        except ImportError:
+            pass
+        else:
+            return pylibmc.Client(servers)
+
+        try:
+            from google.appengine.api import memcache
+        except ImportError:
+            pass
+        else:
+            return memcache.Client()
+
+        try:
+            import memcache
+        except ImportError:
+            pass
+        else:
+            return memcache.Client(servers)
+
+        try:
+            import libmc
+        except ImportError:
+            pass
+        else:
+            return libmc.Client(servers)
+
+
+# backwards compatibility
+GAEMemcachedCache = MemcachedCache
+
+
+class RedisCache(BaseCache):
+    """Uses the Redis key-value store as a cache backend.
+
+    The first argument can be either a string denoting address of the Redis
+    server or an object resembling an instance of a redis.Redis class.
+
+    Note: Python Redis API already takes care of encoding unicode strings on
+    the fly.
+
+    .. versionadded:: 0.7
+
+    .. versionadded:: 0.8
+       `key_prefix` was added.
+
+    .. versionchanged:: 0.8
+       This cache backend now properly serializes objects.
+
+    .. versionchanged:: 0.8.3
+       This cache backend now supports password authentication.
+
+    .. versionchanged:: 0.10
+        ``**kwargs`` is now passed to the redis object.
+
+    :param host: address of the Redis server or an object which API is
+                 compatible with the official Python Redis client (redis-py).
+    :param port: port number on which Redis server listens for connections.
+    :param password: password authentication for the Redis server.
+    :param db: db (zero-based numeric index) on Redis Server to connect.
+    :param default_timeout: the default timeout that is used if no timeout is
+                            specified on :meth:`~BaseCache.set`. A timeout of
+                            0 indicates that the cache never expires.
+    :param key_prefix: A prefix that should be added to all keys.
+
+    Any additional keyword arguments will be passed to ``redis.Redis``.
+    """
+
+    def __init__(
+        self,
+        host="localhost",
+        port=6379,
+        password=None,
+        db=0,
+        default_timeout=300,
+        key_prefix=None,
+        **kwargs
+    ):
+        BaseCache.__init__(self, default_timeout)
+        if host is None:
+            raise ValueError("RedisCache host parameter may not be None")
+        if isinstance(host, string_types):
+            try:
+                import redis
+            except ImportError:
+                raise RuntimeError("no redis module found")
+            if kwargs.get("decode_responses", None):
+                raise ValueError("decode_responses is not supported by RedisCache.")
+            self._client = redis.Redis(
+                host=host, port=port, password=password, db=db, **kwargs
+            )
+        else:
+            self._client = host
+        self.key_prefix = key_prefix or ""
+
+    def _normalize_timeout(self, timeout):
+        timeout = BaseCache._normalize_timeout(self, timeout)
+        if timeout == 0:
+            timeout = -1
+        return timeout
+
+    def dump_object(self, value):
+        """Dumps an object into a string for redis.  By default it serializes
+        integers as regular string and pickle dumps everything else.
+        """
+        t = type(value)
+        if t in integer_types:
+            return str(value).encode("ascii")
+        return b"!" + pickle.dumps(value)
+
+    def load_object(self, value):
+        """The reversal of :meth:`dump_object`.  This might be called with
+        None.
+        """
+        if value is None:
+            return None
+        if value.startswith(b"!"):
+            try:
+                return pickle.loads(value[1:])
+            except pickle.PickleError:
+                return None
+        try:
+            return int(value)
+        except ValueError:
+            # before 0.8 we did not have serialization.  Still support that.
+            return value
+
+    def get(self, key):
+        return self.load_object(self._client.get(self.key_prefix + key))
+
+    def get_many(self, *keys):
+        if self.key_prefix:
+            keys = [self.key_prefix + key for key in keys]
+        return [self.load_object(x) for x in self._client.mget(keys)]
+
+    def set(self, key, value, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        dump = self.dump_object(value)
+        if timeout == -1:
+            result = self._client.set(name=self.key_prefix + key, value=dump)
+        else:
+            result = self._client.setex(
+                name=self.key_prefix + key, value=dump, time=timeout
+            )
+        return result
+
+    def add(self, key, value, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        dump = self.dump_object(value)
+        return self._client.setnx(
+            name=self.key_prefix + key, value=dump
+        ) and self._client.expire(name=self.key_prefix + key, time=timeout)
+
+    def set_many(self, mapping, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        # Use transaction=False to batch without calling redis MULTI
+        # which is not supported by twemproxy
+        pipe = self._client.pipeline(transaction=False)
+
+        for key, value in _items(mapping):
+            dump = self.dump_object(value)
+            if timeout == -1:
+                pipe.set(name=self.key_prefix + key, value=dump)
+            else:
+                pipe.setex(name=self.key_prefix + key, value=dump, time=timeout)
+        return pipe.execute()
+
+    def delete(self, key):
+        return self._client.delete(self.key_prefix + key)
+
+    def delete_many(self, *keys):
+        if not keys:
+            return
+        if self.key_prefix:
+            keys = [self.key_prefix + key for key in keys]
+        return self._client.delete(*keys)
+
+    def has(self, key):
+        return self._client.exists(self.key_prefix + key)
+
+    def clear(self):
+        status = False
+        if self.key_prefix:
+            keys = self._client.keys(self.key_prefix + "*")
+            if keys:
+                status = self._client.delete(*keys)
+        else:
+            status = self._client.flushdb()
+        return status
+
+    def inc(self, key, delta=1):
+        return self._client.incr(name=self.key_prefix + key, amount=delta)
+
+    def dec(self, key, delta=1):
+        return self._client.decr(name=self.key_prefix + key, amount=delta)
+
+
+class FileSystemCache(BaseCache):
+    """A cache that stores the items on the file system.  This cache depends
+    on being the only user of the `cache_dir`.  Make absolutely sure that
+    nobody but this cache stores files there or otherwise the cache will
+    randomly delete files therein.
+
+    :param cache_dir: the directory where cache files are stored.
+    :param threshold: the maximum number of items the cache stores before
+                      it starts deleting some. A threshold value of 0
+                      indicates no threshold.
+    :param default_timeout: the default timeout that is used if no timeout is
+                            specified on :meth:`~BaseCache.set`. A timeout of
+                            0 indicates that the cache never expires.
+    :param mode: the file mode wanted for the cache files, default 0600
+    """
+
+    #: used for temporary files by the FileSystemCache
+    _fs_transaction_suffix = ".__wz_cache"
+    #: keep amount of files in a cache element
+    _fs_count_file = "__wz_cache_count"
+
+    def __init__(self, cache_dir, threshold=500, default_timeout=300, mode=0o600):
+        BaseCache.__init__(self, default_timeout)
+        self._path = cache_dir
+        self._threshold = threshold
+        self._mode = mode
+
+        try:
+            os.makedirs(self._path)
+        except OSError as ex:
+            if ex.errno != errno.EEXIST:
+                raise
+
+        self._update_count(value=len(self._list_dir()))
+
+    @property
+    def _file_count(self):
+        return self.get(self._fs_count_file) or 0
+
+    def _update_count(self, delta=None, value=None):
+        # If we have no threshold, don't count files
+        if self._threshold == 0:
+            return
+
+        if delta:
+            new_count = self._file_count + delta
+        else:
+            new_count = value or 0
+        self.set(self._fs_count_file, new_count, mgmt_element=True)
+
+    def _normalize_timeout(self, timeout):
+        timeout = BaseCache._normalize_timeout(self, timeout)
+        if timeout != 0:
+            timeout = time() + timeout
+        return int(timeout)
+
+    def _list_dir(self):
+        """return a list of (fully qualified) cache filenames
+        """
+        mgmt_files = [
+            self._get_filename(name).split("/")[-1] for name in (self._fs_count_file,)
+        ]
+        return [
+            os.path.join(self._path, fn)
+            for fn in os.listdir(self._path)
+            if not fn.endswith(self._fs_transaction_suffix) and fn not in mgmt_files
+        ]
+
+    def _prune(self):
+        if self._threshold == 0 or not self._file_count > self._threshold:
+            return
+
+        entries = self._list_dir()
+        now = time()
+        for idx, fname in enumerate(entries):
+            try:
+                remove = False
+                with open(fname, "rb") as f:
+                    expires = pickle.load(f)
+                remove = (expires != 0 and expires <= now) or idx % 3 == 0
+
+                if remove:
+                    os.remove(fname)
+            except (IOError, OSError):
+                pass
+        self._update_count(value=len(self._list_dir()))
+
+    def clear(self):
+        for fname in self._list_dir():
+            try:
+                os.remove(fname)
+            except (IOError, OSError):
+                self._update_count(value=len(self._list_dir()))
+                return False
+        self._update_count(value=0)
+        return True
+
+    def _get_filename(self, key):
+        if isinstance(key, text_type):
+            key = key.encode("utf-8")  # XXX unicode review
+        hash = md5(key).hexdigest()
+        return os.path.join(self._path, hash)
+
+    def get(self, key):
+        filename = self._get_filename(key)
+        try:
+            with open(filename, "rb") as f:
+                pickle_time = pickle.load(f)
+                if pickle_time == 0 or pickle_time >= time():
+                    return pickle.load(f)
+                else:
+                    os.remove(filename)
+                    return None
+        except (IOError, OSError, pickle.PickleError):
+            return None
+
+    def add(self, key, value, timeout=None):
+        filename = self._get_filename(key)
+        if not os.path.exists(filename):
+            return self.set(key, value, timeout)
+        return False
+
+    def set(self, key, value, timeout=None, mgmt_element=False):
+        # Management elements have no timeout
+        if mgmt_element:
+            timeout = 0
+
+        # Don't prune on management element update, to avoid loop
+        else:
+            self._prune()
+
+        timeout = self._normalize_timeout(timeout)
+        filename = self._get_filename(key)
+        try:
+            fd, tmp = tempfile.mkstemp(
+                suffix=self._fs_transaction_suffix, dir=self._path
+            )
+            with os.fdopen(fd, "wb") as f:
+                pickle.dump(timeout, f, 1)
+                pickle.dump(value, f, pickle.HIGHEST_PROTOCOL)
+            rename(tmp, filename)
+            os.chmod(filename, self._mode)
+        except (IOError, OSError):
+            return False
+        else:
+            # Management elements should not count towards threshold
+            if not mgmt_element:
+                self._update_count(delta=1)
+            return True
+
+    def delete(self, key, mgmt_element=False):
+        try:
+            os.remove(self._get_filename(key))
+        except (IOError, OSError):
+            return False
+        else:
+            # Management elements should not count towards threshold
+            if not mgmt_element:
+                self._update_count(delta=-1)
+            return True
+
+    def has(self, key):
+        filename = self._get_filename(key)
+        try:
+            with open(filename, "rb") as f:
+                pickle_time = pickle.load(f)
+                if pickle_time == 0 or pickle_time >= time():
+                    return True
+                else:
+                    os.remove(filename)
+                    return False
+        except (IOError, OSError, pickle.PickleError):
+            return False
+
+
+class UWSGICache(BaseCache):
+    """Implements the cache using uWSGI's caching framework.
+
+    .. note::
+        This class cannot be used when running under PyPy, because the uWSGI
+        API implementation for PyPy is lacking the needed functionality.
+
+    :param default_timeout: The default timeout in seconds.
+    :param cache: The name of the caching instance to connect to, for
+        example: mycache@localhost:3031, defaults to an empty string, which
+        means uWSGI will cache in the local instance. If the cache is in the
+        same instance as the werkzeug app, you only have to provide the name of
+        the cache.
+    """
+
+    def __init__(self, default_timeout=300, cache=""):
+        BaseCache.__init__(self, default_timeout)
+
+        if platform.python_implementation() == "PyPy":
+            raise RuntimeError(
+                "uWSGI caching does not work under PyPy, see "
+                "the docs for more details."
+            )
+
+        try:
+            import uwsgi
+
+            self._uwsgi = uwsgi
+        except ImportError:
+            raise RuntimeError(
+                "uWSGI could not be imported, are you running under uWSGI?"
+            )
+
+        self.cache = cache
+
+    def get(self, key):
+        rv = self._uwsgi.cache_get(key, self.cache)
+        if rv is None:
+            return
+        return pickle.loads(rv)
+
+    def delete(self, key):
+        return self._uwsgi.cache_del(key, self.cache)
+
+    def set(self, key, value, timeout=None):
+        return self._uwsgi.cache_update(
+            key, pickle.dumps(value), self._normalize_timeout(timeout), self.cache
+        )
+
+    def add(self, key, value, timeout=None):
+        return self._uwsgi.cache_set(
+            key, pickle.dumps(value), self._normalize_timeout(timeout), self.cache
+        )
+
+    def clear(self):
+        return self._uwsgi.cache_clear(self.cache)
+
+    def has(self, key):
+        return self._uwsgi.cache_exists(key, self.cache) is not None
diff --git a/python/werkzeug/contrib/fixers.py b/python/werkzeug/contrib/fixers.py
new file mode 100644
index 0000000..8df0afd
--- /dev/null
+++ b/python/werkzeug/contrib/fixers.py
@@ -0,0 +1,262 @@
+"""
+Fixers
+======
+
+.. warning::
+    .. deprecated:: 0.15
+        ``ProxyFix`` has moved to :mod:`werkzeug.middleware.proxy_fix`.
+        All other code in this module is deprecated and will be removed
+        in version 1.0.
+
+.. versionadded:: 0.5
+
+This module includes various helpers that fix web server behavior.
+
+.. autoclass:: ProxyFix
+   :members:
+
+.. autoclass:: CGIRootFix
+
+.. autoclass:: PathInfoFromRequestUriFix
+
+.. autoclass:: HeaderRewriterFix
+
+.. autoclass:: InternetExplorerFix
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+import warnings
+
+from ..datastructures import Headers
+from ..datastructures import ResponseCacheControl
+from ..http import parse_cache_control_header
+from ..http import parse_options_header
+from ..http import parse_set_header
+from ..middleware.proxy_fix import ProxyFix as _ProxyFix
+from ..useragents import UserAgent
+
+try:
+    from urllib.parse import unquote
+except ImportError:
+    from urllib import unquote
+
+
+class CGIRootFix(object):
+    """Wrap the application in this middleware if you are using FastCGI
+    or CGI and you have problems with your app root being set to the CGI
+    script's path instead of the path users are going to visit.
+
+    :param app: the WSGI application
+    :param app_root: Defaulting to ``'/'``, you can set this to
+        something else if your app is mounted somewhere else.
+
+    .. deprecated:: 0.15
+        This middleware will be removed in version 1.0.
+
+    .. versionchanged:: 0.9
+        Added `app_root` parameter and renamed from
+        ``LighttpdCGIRootFix``.
+    """
+
+    def __init__(self, app, app_root="/"):
+        warnings.warn(
+            "'CGIRootFix' is deprecated as of version 0.15 and will be"
+            " removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.app = app
+        self.app_root = app_root.strip("/")
+
+    def __call__(self, environ, start_response):
+        environ["SCRIPT_NAME"] = self.app_root
+        return self.app(environ, start_response)
+
+
+class LighttpdCGIRootFix(CGIRootFix):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'LighttpdCGIRootFix' is renamed 'CGIRootFix'. Both will be"
+            " removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(LighttpdCGIRootFix, self).__init__(*args, **kwargs)
+
+
+class PathInfoFromRequestUriFix(object):
+    """On windows environment variables are limited to the system charset
+    which makes it impossible to store the `PATH_INFO` variable in the
+    environment without loss of information on some systems.
+
+    This is for example a problem for CGI scripts on a Windows Apache.
+
+    This fixer works by recreating the `PATH_INFO` from `REQUEST_URI`,
+    `REQUEST_URL`, or `UNENCODED_URL` (whatever is available).  Thus the
+    fix can only be applied if the webserver supports either of these
+    variables.
+
+    :param app: the WSGI application
+
+    .. deprecated:: 0.15
+        This middleware will be removed in version 1.0.
+    """
+
+    def __init__(self, app):
+        warnings.warn(
+            "'PathInfoFromRequestUriFix' is deprecated as of version"
+            " 0.15 and will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.app = app
+
+    def __call__(self, environ, start_response):
+        for key in "REQUEST_URL", "REQUEST_URI", "UNENCODED_URL":
+            if key not in environ:
+                continue
+            request_uri = unquote(environ[key])
+            script_name = unquote(environ.get("SCRIPT_NAME", ""))
+            if request_uri.startswith(script_name):
+                environ["PATH_INFO"] = request_uri[len(script_name) :].split("?", 1)[0]
+                break
+        return self.app(environ, start_response)
+
+
+class ProxyFix(_ProxyFix):
+    """
+    .. deprecated:: 0.15
+        ``werkzeug.contrib.fixers.ProxyFix`` has moved to
+        :mod:`werkzeug.middleware.proxy_fix`. This import will be
+        removed in 1.0.
+    """
+
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.contrib.fixers.ProxyFix' has moved to 'werkzeug"
+            ".middleware.proxy_fix.ProxyFix'. This import is deprecated"
+            " as of version 0.15 and will be removed in 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(ProxyFix, self).__init__(*args, **kwargs)
+
+
+class HeaderRewriterFix(object):
+    """This middleware can remove response headers and add others.  This
+    is for example useful to remove the `Date` header from responses if you
+    are using a server that adds that header, no matter if it's present or
+    not or to add `X-Powered-By` headers::
+
+        app = HeaderRewriterFix(app, remove_headers=['Date'],
+                                add_headers=[('X-Powered-By', 'WSGI')])
+
+    :param app: the WSGI application
+    :param remove_headers: a sequence of header keys that should be
+                           removed.
+    :param add_headers: a sequence of ``(key, value)`` tuples that should
+                        be added.
+
+    .. deprecated:: 0.15
+        This middleware will be removed in 1.0.
+    """
+
+    def __init__(self, app, remove_headers=None, add_headers=None):
+        warnings.warn(
+            "'HeaderRewriterFix' is deprecated as of version 0.15 and"
+            " will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.app = app
+        self.remove_headers = set(x.lower() for x in (remove_headers or ()))
+        self.add_headers = list(add_headers or ())
+
+    def __call__(self, environ, start_response):
+        def rewriting_start_response(status, headers, exc_info=None):
+            new_headers = []
+            for key, value in headers:
+                if key.lower() not in self.remove_headers:
+                    new_headers.append((key, value))
+            new_headers += self.add_headers
+            return start_response(status, new_headers, exc_info)
+
+        return self.app(environ, rewriting_start_response)
+
+
+class InternetExplorerFix(object):
+    """This middleware fixes a couple of bugs with Microsoft Internet
+    Explorer.  Currently the following fixes are applied:
+
+    -   removing of `Vary` headers for unsupported mimetypes which
+        causes troubles with caching.  Can be disabled by passing
+        ``fix_vary=False`` to the constructor.
+        see: https://support.microsoft.com/en-us/help/824847
+
+    -   removes offending headers to work around caching bugs in
+        Internet Explorer if `Content-Disposition` is set.  Can be
+        disabled by passing ``fix_attach=False`` to the constructor.
+
+    If it does not detect affected Internet Explorer versions it won't touch
+    the request / response.
+
+    .. deprecated:: 0.15
+        This middleware will be removed in 1.0.
+    """
+
+    # This code was inspired by Django fixers for the same bugs.  The
+    # fix_vary and fix_attach fixers were originally implemented in Django
+    # by Michael Axiak and is available as part of the Django project:
+    #     https://code.djangoproject.com/ticket/4148
+
+    def __init__(self, app, fix_vary=True, fix_attach=True):
+        warnings.warn(
+            "'InternetExplorerFix' is deprecated as of version 0.15 and"
+            " will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.app = app
+        self.fix_vary = fix_vary
+        self.fix_attach = fix_attach
+
+    def fix_headers(self, environ, headers, status=None):
+        if self.fix_vary:
+            header = headers.get("content-type", "")
+            mimetype, options = parse_options_header(header)
+            if mimetype not in ("text/html", "text/plain", "text/sgml"):
+                headers.pop("vary", None)
+
+        if self.fix_attach and "content-disposition" in headers:
+            pragma = parse_set_header(headers.get("pragma", ""))
+            pragma.discard("no-cache")
+            header = pragma.to_header()
+            if not header:
+                headers.pop("pragma", "")
+            else:
+                headers["Pragma"] = header
+            header = headers.get("cache-control", "")
+            if header:
+                cc = parse_cache_control_header(header, cls=ResponseCacheControl)
+                cc.no_cache = None
+                cc.no_store = False
+                header = cc.to_header()
+                if not header:
+                    headers.pop("cache-control", "")
+                else:
+                    headers["Cache-Control"] = header
+
+    def run_fixed(self, environ, start_response):
+        def fixing_start_response(status, headers, exc_info=None):
+            headers = Headers(headers)
+            self.fix_headers(environ, headers, status)
+            return start_response(status, headers.to_wsgi_list(), exc_info)
+
+        return self.app(environ, fixing_start_response)
+
+    def __call__(self, environ, start_response):
+        ua = UserAgent(environ)
+        if ua.browser != "msie":
+            return self.app(environ, start_response)
+        return self.run_fixed(environ, start_response)
diff --git a/python/werkzeug/contrib/iterio.py b/python/werkzeug/contrib/iterio.py
new file mode 100644
index 0000000..b672454
--- /dev/null
+++ b/python/werkzeug/contrib/iterio.py
@@ -0,0 +1,358 @@
+# -*- coding: utf-8 -*-
+r"""
+    werkzeug.contrib.iterio
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    This module implements a :class:`IterIO` that converts an iterator into
+    a stream object and the other way round.  Converting streams into
+    iterators requires the `greenlet`_ module.
+
+    To convert an iterator into a stream all you have to do is to pass it
+    directly to the :class:`IterIO` constructor.  In this example we pass it
+    a newly created generator::
+
+        def foo():
+            yield "something\n"
+            yield "otherthings"
+        stream = IterIO(foo())
+        print stream.read()         # read the whole iterator
+
+    The other way round works a bit different because we have to ensure that
+    the code execution doesn't take place yet.  An :class:`IterIO` call with a
+    callable as first argument does two things.  The function itself is passed
+    an :class:`IterIO` stream it can feed.  The object returned by the
+    :class:`IterIO` constructor on the other hand is not an stream object but
+    an iterator::
+
+        def foo(stream):
+            stream.write("some")
+            stream.write("thing")
+            stream.flush()
+            stream.write("otherthing")
+        iterator = IterIO(foo)
+        print iterator.next()       # prints something
+        print iterator.next()       # prints otherthing
+        iterator.next()             # raises StopIteration
+
+    .. _greenlet: https://github.com/python-greenlet/greenlet
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import warnings
+
+from .._compat import implements_iterator
+
+try:
+    import greenlet
+except ImportError:
+    greenlet = None
+
+warnings.warn(
+    "'werkzeug.contrib.iterio' is deprecated as of version 0.15 and"
+    " will be removed in version 1.0.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+
+def _mixed_join(iterable, sentinel):
+    """concatenate any string type in an intelligent way."""
+    iterator = iter(iterable)
+    first_item = next(iterator, sentinel)
+    if isinstance(first_item, bytes):
+        return first_item + b"".join(iterator)
+    return first_item + u"".join(iterator)
+
+
+def _newline(reference_string):
+    if isinstance(reference_string, bytes):
+        return b"\n"
+    return u"\n"
+
+
+@implements_iterator
+class IterIO(object):
+    """Instances of this object implement an interface compatible with the
+    standard Python :class:`file` object.  Streams are either read-only or
+    write-only depending on how the object is created.
+
+    If the first argument is an iterable a file like object is returned that
+    returns the contents of the iterable.  In case the iterable is empty
+    read operations will return the sentinel value.
+
+    If the first argument is a callable then the stream object will be
+    created and passed to that function.  The caller itself however will
+    not receive a stream but an iterable.  The function will be executed
+    step by step as something iterates over the returned iterable.  Each
+    call to :meth:`flush` will create an item for the iterable.  If
+    :meth:`flush` is called without any writes in-between the sentinel
+    value will be yielded.
+
+    Note for Python 3: due to the incompatible interface of bytes and
+    streams you should set the sentinel value explicitly to an empty
+    bytestring (``b''``) if you are expecting to deal with bytes as
+    otherwise the end of the stream is marked with the wrong sentinel
+    value.
+
+    .. versionadded:: 0.9
+       `sentinel` parameter was added.
+    """
+
+    def __new__(cls, obj, sentinel=""):
+        try:
+            iterator = iter(obj)
+        except TypeError:
+            return IterI(obj, sentinel)
+        return IterO(iterator, sentinel)
+
+    def __iter__(self):
+        return self
+
+    def tell(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        return self.pos
+
+    def isatty(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        return False
+
+    def seek(self, pos, mode=0):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def truncate(self, size=None):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def write(self, s):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def writelines(self, list):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def read(self, n=-1):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def readlines(self, sizehint=0):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def readline(self, length=None):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def flush(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        raise IOError(9, "Bad file descriptor")
+
+    def __next__(self):
+        if self.closed:
+            raise StopIteration()
+        line = self.readline()
+        if not line:
+            raise StopIteration()
+        return line
+
+
+class IterI(IterIO):
+    """Convert an stream into an iterator."""
+
+    def __new__(cls, func, sentinel=""):
+        if greenlet is None:
+            raise RuntimeError("IterI requires greenlet support")
+        stream = object.__new__(cls)
+        stream._parent = greenlet.getcurrent()
+        stream._buffer = []
+        stream.closed = False
+        stream.sentinel = sentinel
+        stream.pos = 0
+
+        def run():
+            func(stream)
+            stream.close()
+
+        g = greenlet.greenlet(run, stream._parent)
+        while 1:
+            rv = g.switch()
+            if not rv:
+                return
+            yield rv[0]
+
+    def close(self):
+        if not self.closed:
+            self.closed = True
+            self._flush_impl()
+
+    def write(self, s):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        if s:
+            self.pos += len(s)
+            self._buffer.append(s)
+
+    def writelines(self, list):
+        for item in list:
+            self.write(item)
+
+    def flush(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        self._flush_impl()
+
+    def _flush_impl(self):
+        data = _mixed_join(self._buffer, self.sentinel)
+        self._buffer = []
+        if not data and self.closed:
+            self._parent.switch()
+        else:
+            self._parent.switch((data,))
+
+
+class IterO(IterIO):
+    """Iter output.  Wrap an iterator and give it a stream like interface."""
+
+    def __new__(cls, gen, sentinel=""):
+        self = object.__new__(cls)
+        self._gen = gen
+        self._buf = None
+        self.sentinel = sentinel
+        self.closed = False
+        self.pos = 0
+        return self
+
+    def __iter__(self):
+        return self
+
+    def _buf_append(self, string):
+        """Replace string directly without appending to an empty string,
+        avoiding type issues."""
+        if not self._buf:
+            self._buf = string
+        else:
+            self._buf += string
+
+    def close(self):
+        if not self.closed:
+            self.closed = True
+            if hasattr(self._gen, "close"):
+                self._gen.close()
+
+    def seek(self, pos, mode=0):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        if mode == 1:
+            pos += self.pos
+        elif mode == 2:
+            self.read()
+            self.pos = min(self.pos, self.pos + pos)
+            return
+        elif mode != 0:
+            raise IOError("Invalid argument")
+        buf = []
+        try:
+            tmp_end_pos = len(self._buf or "")
+            while pos > tmp_end_pos:
+                item = next(self._gen)
+                tmp_end_pos += len(item)
+                buf.append(item)
+        except StopIteration:
+            pass
+        if buf:
+            self._buf_append(_mixed_join(buf, self.sentinel))
+        self.pos = max(0, pos)
+
+    def read(self, n=-1):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        if n < 0:
+            self._buf_append(_mixed_join(self._gen, self.sentinel))
+            result = self._buf[self.pos :]
+            self.pos += len(result)
+            return result
+        new_pos = self.pos + n
+        buf = []
+        try:
+            tmp_end_pos = 0 if self._buf is None else len(self._buf)
+            while new_pos > tmp_end_pos or (self._buf is None and not buf):
+                item = next(self._gen)
+                tmp_end_pos += len(item)
+                buf.append(item)
+        except StopIteration:
+            pass
+        if buf:
+            self._buf_append(_mixed_join(buf, self.sentinel))
+
+        if self._buf is None:
+            return self.sentinel
+
+        new_pos = max(0, new_pos)
+        try:
+            return self._buf[self.pos : new_pos]
+        finally:
+            self.pos = min(new_pos, len(self._buf))
+
+    def readline(self, length=None):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+
+        nl_pos = -1
+        if self._buf:
+            nl_pos = self._buf.find(_newline(self._buf), self.pos)
+        buf = []
+        try:
+            if self._buf is None:
+                pos = self.pos
+            else:
+                pos = len(self._buf)
+            while nl_pos < 0:
+                item = next(self._gen)
+                local_pos = item.find(_newline(item))
+                buf.append(item)
+                if local_pos >= 0:
+                    nl_pos = pos + local_pos
+                    break
+                pos += len(item)
+        except StopIteration:
+            pass
+        if buf:
+            self._buf_append(_mixed_join(buf, self.sentinel))
+
+        if self._buf is None:
+            return self.sentinel
+
+        if nl_pos < 0:
+            new_pos = len(self._buf)
+        else:
+            new_pos = nl_pos + 1
+        if length is not None and self.pos + length < new_pos:
+            new_pos = self.pos + length
+        try:
+            return self._buf[self.pos : new_pos]
+        finally:
+            self.pos = min(new_pos, len(self._buf))
+
+    def readlines(self, sizehint=0):
+        total = 0
+        lines = []
+        line = self.readline()
+        while line:
+            lines.append(line)
+            total += len(line)
+            if 0 < sizehint <= total:
+                break
+            line = self.readline()
+        return lines
diff --git a/python/werkzeug/contrib/lint.py b/python/werkzeug/contrib/lint.py
new file mode 100644
index 0000000..8bd8b8a
--- /dev/null
+++ b/python/werkzeug/contrib/lint.py
@@ -0,0 +1,11 @@
+import warnings
+
+from ..middleware.lint import *  # noqa: F401, F403
+
+warnings.warn(
+    "'werkzeug.contrib.lint' has moved to 'werkzeug.middleware.lint'."
+    " This import is deprecated as of version 0.15 and will be removed"
+    " in version 1.0.",
+    DeprecationWarning,
+    stacklevel=2,
+)
diff --git a/python/werkzeug/contrib/profiler.py b/python/werkzeug/contrib/profiler.py
new file mode 100644
index 0000000..b79fe56
--- /dev/null
+++ b/python/werkzeug/contrib/profiler.py
@@ -0,0 +1,42 @@
+import warnings
+
+from ..middleware.profiler import *  # noqa: F401, F403
+
+warnings.warn(
+    "'werkzeug.contrib.profiler' has moved to"
+    "'werkzeug.middleware.profiler'. This import is deprecated as of"
+    "version 0.15 and will be removed in version 1.0.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+
+class MergeStream(object):
+    """An object that redirects ``write`` calls to multiple streams.
+    Use this to log to both ``sys.stdout`` and a file::
+
+        f = open('profiler.log', 'w')
+        stream = MergeStream(sys.stdout, f)
+        profiler = ProfilerMiddleware(app, stream)
+
+    .. deprecated:: 0.15
+        Use the ``tee`` command in your terminal instead. This class
+        will be removed in 1.0.
+    """
+
+    def __init__(self, *streams):
+        warnings.warn(
+            "'MergeStream' is deprecated as of version 0.15 and will be removed in"
+            " version 1.0. Use your terminal's 'tee' command instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+
+        if not streams:
+            raise TypeError("At least one stream must be given.")
+
+        self.streams = streams
+
+    def write(self, data):
+        for stream in self.streams:
+            stream.write(data)
diff --git a/python/werkzeug/contrib/securecookie.py b/python/werkzeug/contrib/securecookie.py
new file mode 100644
index 0000000..c4c9eee
--- /dev/null
+++ b/python/werkzeug/contrib/securecookie.py
@@ -0,0 +1,362 @@
+# -*- coding: utf-8 -*-
+r"""
+    werkzeug.contrib.securecookie
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    This module implements a cookie that is not alterable from the client
+    because it adds a checksum the server checks for.  You can use it as
+    session replacement if all you have is a user id or something to mark
+    a logged in user.
+
+    Keep in mind that the data is still readable from the client as a
+    normal cookie is.  However you don't have to store and flush the
+    sessions you have at the server.
+
+    Example usage:
+
+    >>> from werkzeug.contrib.securecookie import SecureCookie
+    >>> x = SecureCookie({"foo": 42, "baz": (1, 2, 3)}, "deadbeef")
+
+    Dumping into a string so that one can store it in a cookie:
+
+    >>> value = x.serialize()
+
+    Loading from that string again:
+
+    >>> x = SecureCookie.unserialize(value, "deadbeef")
+    >>> x["baz"]
+    (1, 2, 3)
+
+    If someone modifies the cookie and the checksum is wrong the unserialize
+    method will fail silently and return a new empty `SecureCookie` object.
+
+    Keep in mind that the values will be visible in the cookie so do not
+    store data in a cookie you don't want the user to see.
+
+    Application Integration
+    =======================
+
+    If you are using the werkzeug request objects you could integrate the
+    secure cookie into your application like this::
+
+        from werkzeug.utils import cached_property
+        from werkzeug.wrappers import BaseRequest
+        from werkzeug.contrib.securecookie import SecureCookie
+
+        # don't use this key but a different one; you could just use
+        # os.urandom(20) to get something random
+        SECRET_KEY = '\xfa\xdd\xb8z\xae\xe0}4\x8b\xea'
+
+        class Request(BaseRequest):
+
+            @cached_property
+            def client_session(self):
+                data = self.cookies.get('session_data')
+                if not data:
+                    return SecureCookie(secret_key=SECRET_KEY)
+                return SecureCookie.unserialize(data, SECRET_KEY)
+
+        def application(environ, start_response):
+            request = Request(environ)
+
+            # get a response object here
+            response = ...
+
+            if request.client_session.should_save:
+                session_data = request.client_session.serialize()
+                response.set_cookie('session_data', session_data,
+                                    httponly=True)
+            return response(environ, start_response)
+
+    A less verbose integration can be achieved by using shorthand methods::
+
+        class Request(BaseRequest):
+
+            @cached_property
+            def client_session(self):
+                return SecureCookie.load_cookie(self, secret_key=COOKIE_SECRET)
+
+        def application(environ, start_response):
+            request = Request(environ)
+
+            # get a response object here
+            response = ...
+
+            request.client_session.save_cookie(response)
+            return response(environ, start_response)
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import base64
+import pickle
+import warnings
+from hashlib import sha1 as _default_hash
+from hmac import new as hmac
+from time import time
+
+from .._compat import iteritems
+from .._compat import text_type
+from .._compat import to_bytes
+from .._compat import to_native
+from .._internal import _date_to_unix
+from ..contrib.sessions import ModificationTrackingDict
+from ..security import safe_str_cmp
+from ..urls import url_quote_plus
+from ..urls import url_unquote_plus
+
+warnings.warn(
+    "'werkzeug.contrib.securecookie' is deprecated as of version 0.15"
+    " and will be removed in version 1.0. It has moved to"
+    " https://github.com/pallets/secure-cookie.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+
+class UnquoteError(Exception):
+    """Internal exception used to signal failures on quoting."""
+
+
+class SecureCookie(ModificationTrackingDict):
+    """Represents a secure cookie.  You can subclass this class and provide
+    an alternative mac method.  The import thing is that the mac method
+    is a function with a similar interface to the hashlib.  Required
+    methods are update() and digest().
+
+    Example usage:
+
+    >>> x = SecureCookie({"foo": 42, "baz": (1, 2, 3)}, "deadbeef")
+    >>> x["foo"]
+    42
+    >>> x["baz"]
+    (1, 2, 3)
+    >>> x["blafasel"] = 23
+    >>> x.should_save
+    True
+
+    :param data: the initial data.  Either a dict, list of tuples or `None`.
+    :param secret_key: the secret key.  If not set `None` or not specified
+                       it has to be set before :meth:`serialize` is called.
+    :param new: The initial value of the `new` flag.
+    """
+
+    #: The hash method to use.  This has to be a module with a new function
+    #: or a function that creates a hashlib object.  Such as `hashlib.md5`
+    #: Subclasses can override this attribute.  The default hash is sha1.
+    #: Make sure to wrap this in staticmethod() if you store an arbitrary
+    #: function there such as hashlib.sha1 which  might be implemented
+    #: as a function.
+    hash_method = staticmethod(_default_hash)
+
+    #: The module used for serialization. Should have a ``dumps`` and a
+    #: ``loads`` method that takes bytes. The default is :mod:`pickle`.
+    #:
+    #: .. versionchanged:: 0.15
+    #:     The default of ``pickle`` will change to :mod:`json` in 1.0.
+    serialization_method = pickle
+
+    #: if the contents should be base64 quoted.  This can be disabled if the
+    #: serialization process returns cookie safe strings only.
+    quote_base64 = True
+
+    def __init__(self, data=None, secret_key=None, new=True):
+        ModificationTrackingDict.__init__(self, data or ())
+        # explicitly convert it into a bytestring because python 2.6
+        # no longer performs an implicit string conversion on hmac
+        if secret_key is not None:
+            secret_key = to_bytes(secret_key, "utf-8")
+        self.secret_key = secret_key
+        self.new = new
+
+        if self.serialization_method is pickle:
+            warnings.warn(
+                "The default 'SecureCookie.serialization_method' will"
+                " change from pickle to json in version 1.0. To upgrade"
+                " existing tokens, override 'unquote' to try pickle if"
+                " json fails.",
+                stacklevel=2,
+            )
+
+    def __repr__(self):
+        return "<%s %s%s>" % (
+            self.__class__.__name__,
+            dict.__repr__(self),
+            "*" if self.should_save else "",
+        )
+
+    @property
+    def should_save(self):
+        """True if the session should be saved.  By default this is only true
+        for :attr:`modified` cookies, not :attr:`new`.
+        """
+        return self.modified
+
+    @classmethod
+    def quote(cls, value):
+        """Quote the value for the cookie.  This can be any object supported
+        by :attr:`serialization_method`.
+
+        :param value: the value to quote.
+        """
+        if cls.serialization_method is not None:
+            value = cls.serialization_method.dumps(value)
+        if cls.quote_base64:
+            value = b"".join(
+                base64.b64encode(to_bytes(value, "utf8")).splitlines()
+            ).strip()
+        return value
+
+    @classmethod
+    def unquote(cls, value):
+        """Unquote the value for the cookie.  If unquoting does not work a
+        :exc:`UnquoteError` is raised.
+
+        :param value: the value to unquote.
+        """
+        try:
+            if cls.quote_base64:
+                value = base64.b64decode(value)
+            if cls.serialization_method is not None:
+                value = cls.serialization_method.loads(value)
+            return value
+        except Exception:
+            # unfortunately pickle and other serialization modules can
+            # cause pretty every error here.  if we get one we catch it
+            # and convert it into an UnquoteError
+            raise UnquoteError()
+
+    def serialize(self, expires=None):
+        """Serialize the secure cookie into a string.
+
+        If expires is provided, the session will be automatically invalidated
+        after expiration when you unseralize it. This provides better
+        protection against session cookie theft.
+
+        :param expires: an optional expiration date for the cookie (a
+                        :class:`datetime.datetime` object)
+        """
+        if self.secret_key is None:
+            raise RuntimeError("no secret key defined")
+        if expires:
+            self["_expires"] = _date_to_unix(expires)
+        result = []
+        mac = hmac(self.secret_key, None, self.hash_method)
+        for key, value in sorted(self.items()):
+            result.append(
+                (
+                    "%s=%s" % (url_quote_plus(key), self.quote(value).decode("ascii"))
+                ).encode("ascii")
+            )
+            mac.update(b"|" + result[-1])
+        return b"?".join([base64.b64encode(mac.digest()).strip(), b"&".join(result)])
+
+    @classmethod
+    def unserialize(cls, string, secret_key):
+        """Load the secure cookie from a serialized string.
+
+        :param string: the cookie value to unserialize.
+        :param secret_key: the secret key used to serialize the cookie.
+        :return: a new :class:`SecureCookie`.
+        """
+        if isinstance(string, text_type):
+            string = string.encode("utf-8", "replace")
+        if isinstance(secret_key, text_type):
+            secret_key = secret_key.encode("utf-8", "replace")
+        try:
+            base64_hash, data = string.split(b"?", 1)
+        except (ValueError, IndexError):
+            items = ()
+        else:
+            items = {}
+            mac = hmac(secret_key, None, cls.hash_method)
+            for item in data.split(b"&"):
+                mac.update(b"|" + item)
+                if b"=" not in item:
+                    items = None
+                    break
+                key, value = item.split(b"=", 1)
+                # try to make the key a string
+                key = url_unquote_plus(key.decode("ascii"))
+                try:
+                    key = to_native(key)
+                except UnicodeError:
+                    pass
+                items[key] = value
+
+            # no parsing error and the mac looks okay, we can now
+            # sercurely unpickle our cookie.
+            try:
+                client_hash = base64.b64decode(base64_hash)
+            except TypeError:
+                items = client_hash = None
+            if items is not None and safe_str_cmp(client_hash, mac.digest()):
+                try:
+                    for key, value in iteritems(items):
+                        items[key] = cls.unquote(value)
+                except UnquoteError:
+                    items = ()
+                else:
+                    if "_expires" in items:
+                        if time() > items["_expires"]:
+                            items = ()
+                        else:
+                            del items["_expires"]
+            else:
+                items = ()
+        return cls(items, secret_key, False)
+
+    @classmethod
+    def load_cookie(cls, request, key="session", secret_key=None):
+        """Loads a :class:`SecureCookie` from a cookie in request.  If the
+        cookie is not set, a new :class:`SecureCookie` instanced is
+        returned.
+
+        :param request: a request object that has a `cookies` attribute
+                        which is a dict of all cookie values.
+        :param key: the name of the cookie.
+        :param secret_key: the secret key used to unquote the cookie.
+                           Always provide the value even though it has
+                           no default!
+        """
+        data = request.cookies.get(key)
+        if not data:
+            return cls(secret_key=secret_key)
+        return cls.unserialize(data, secret_key)
+
+    def save_cookie(
+        self,
+        response,
+        key="session",
+        expires=None,
+        session_expires=None,
+        max_age=None,
+        path="/",
+        domain=None,
+        secure=None,
+        httponly=False,
+        force=False,
+    ):
+        """Saves the SecureCookie in a cookie on response object.  All
+        parameters that are not described here are forwarded directly
+        to :meth:`~BaseResponse.set_cookie`.
+
+        :param response: a response object that has a
+                         :meth:`~BaseResponse.set_cookie` method.
+        :param key: the name of the cookie.
+        :param session_expires: the expiration date of the secure cookie
+                                stored information.  If this is not provided
+                                the cookie `expires` date is used instead.
+        """
+        if force or self.should_save:
+            data = self.serialize(session_expires or expires)
+            response.set_cookie(
+                key,
+                data,
+                expires=expires,
+                max_age=max_age,
+                path=path,
+                domain=domain,
+                secure=secure,
+                httponly=httponly,
+            )
diff --git a/python/werkzeug/contrib/sessions.py b/python/werkzeug/contrib/sessions.py
new file mode 100644
index 0000000..866e827
--- /dev/null
+++ b/python/werkzeug/contrib/sessions.py
@@ -0,0 +1,389 @@
+# -*- coding: utf-8 -*-
+r"""
+    werkzeug.contrib.sessions
+    ~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    This module contains some helper classes that help one to add session
+    support to a python WSGI application.  For full client-side session
+    storage see :mod:`~werkzeug.contrib.securecookie` which implements a
+    secure, client-side session storage.
+
+
+    Application Integration
+    =======================
+
+    ::
+
+        from werkzeug.contrib.sessions import SessionMiddleware, \
+             FilesystemSessionStore
+
+        app = SessionMiddleware(app, FilesystemSessionStore())
+
+    The current session will then appear in the WSGI environment as
+    `werkzeug.session`.  However it's recommended to not use the middleware
+    but the stores directly in the application.  However for very simple
+    scripts a middleware for sessions could be sufficient.
+
+    This module does not implement methods or ways to check if a session is
+    expired.  That should be done by a cronjob and storage specific.  For
+    example to prune unused filesystem sessions one could check the modified
+    time of the files.  If sessions are stored in the database the new()
+    method should add an expiration timestamp for the session.
+
+    For better flexibility it's recommended to not use the middleware but the
+    store and session object directly in the application dispatching::
+
+        session_store = FilesystemSessionStore()
+
+        def application(environ, start_response):
+            request = Request(environ)
+            sid = request.cookies.get('cookie_name')
+            if sid is None:
+                request.session = session_store.new()
+            else:
+                request.session = session_store.get(sid)
+            response = get_the_response_object(request)
+            if request.session.should_save:
+                session_store.save(request.session)
+                response.set_cookie('cookie_name', request.session.sid)
+            return response(environ, start_response)
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import os
+import re
+import tempfile
+import warnings
+from hashlib import sha1
+from os import path
+from pickle import dump
+from pickle import HIGHEST_PROTOCOL
+from pickle import load
+from random import random
+from time import time
+
+from .._compat import PY2
+from .._compat import text_type
+from ..datastructures import CallbackDict
+from ..filesystem import get_filesystem_encoding
+from ..posixemulation import rename
+from ..utils import dump_cookie
+from ..utils import parse_cookie
+from ..wsgi import ClosingIterator
+
+warnings.warn(
+    "'werkzeug.contrib.sessions' is deprecated as of version 0.15 and"
+    " will be removed in version 1.0. It has moved to"
+    " https://github.com/pallets/secure-cookie.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
+_sha1_re = re.compile(r"^[a-f0-9]{40}$")
+
+
+def _urandom():
+    if hasattr(os, "urandom"):
+        return os.urandom(30)
+    return text_type(random()).encode("ascii")
+
+
+def generate_key(salt=None):
+    if salt is None:
+        salt = repr(salt).encode("ascii")
+    return sha1(b"".join([salt, str(time()).encode("ascii"), _urandom()])).hexdigest()
+
+
+class ModificationTrackingDict(CallbackDict):
+    __slots__ = ("modified",)
+
+    def __init__(self, *args, **kwargs):
+        def on_update(self):
+            self.modified = True
+
+        self.modified = False
+        CallbackDict.__init__(self, on_update=on_update)
+        dict.update(self, *args, **kwargs)
+
+    def copy(self):
+        """Create a flat copy of the dict."""
+        missing = object()
+        result = object.__new__(self.__class__)
+        for name in self.__slots__:
+            val = getattr(self, name, missing)
+            if val is not missing:
+                setattr(result, name, val)
+        return result
+
+    def __copy__(self):
+        return self.copy()
+
+
+class Session(ModificationTrackingDict):
+    """Subclass of a dict that keeps track of direct object changes.  Changes
+    in mutable structures are not tracked, for those you have to set
+    `modified` to `True` by hand.
+    """
+
+    __slots__ = ModificationTrackingDict.__slots__ + ("sid", "new")
+
+    def __init__(self, data, sid, new=False):
+        ModificationTrackingDict.__init__(self, data)
+        self.sid = sid
+        self.new = new
+
+    def __repr__(self):
+        return "<%s %s%s>" % (
+            self.__class__.__name__,
+            dict.__repr__(self),
+            "*" if self.should_save else "",
+        )
+
+    @property
+    def should_save(self):
+        """True if the session should be saved.
+
+        .. versionchanged:: 0.6
+           By default the session is now only saved if the session is
+           modified, not if it is new like it was before.
+        """
+        return self.modified
+
+
+class SessionStore(object):
+    """Baseclass for all session stores.  The Werkzeug contrib module does not
+    implement any useful stores besides the filesystem store, application
+    developers are encouraged to create their own stores.
+
+    :param session_class: The session class to use.  Defaults to
+                          :class:`Session`.
+    """
+
+    def __init__(self, session_class=None):
+        if session_class is None:
+            session_class = Session
+        self.session_class = session_class
+
+    def is_valid_key(self, key):
+        """Check if a key has the correct format."""
+        return _sha1_re.match(key) is not None
+
+    def generate_key(self, salt=None):
+        """Simple function that generates a new session key."""
+        return generate_key(salt)
+
+    def new(self):
+        """Generate a new session."""
+        return self.session_class({}, self.generate_key(), True)
+
+    def save(self, session):
+        """Save a session."""
+
+    def save_if_modified(self, session):
+        """Save if a session class wants an update."""
+        if session.should_save:
+            self.save(session)
+
+    def delete(self, session):
+        """Delete a session."""
+
+    def get(self, sid):
+        """Get a session for this sid or a new session object.  This method
+        has to check if the session key is valid and create a new session if
+        that wasn't the case.
+        """
+        return self.session_class({}, sid, True)
+
+
+#: used for temporary files by the filesystem session store
+_fs_transaction_suffix = ".__wz_sess"
+
+
+class FilesystemSessionStore(SessionStore):
+    """Simple example session store that saves sessions on the filesystem.
+    This store works best on POSIX systems and Windows Vista / Windows
+    Server 2008 and newer.
+
+    .. versionchanged:: 0.6
+       `renew_missing` was added.  Previously this was considered `True`,
+       now the default changed to `False` and it can be explicitly
+       deactivated.
+
+    :param path: the path to the folder used for storing the sessions.
+                 If not provided the default temporary directory is used.
+    :param filename_template: a string template used to give the session
+                              a filename.  ``%s`` is replaced with the
+                              session id.
+    :param session_class: The session class to use.  Defaults to
+                          :class:`Session`.
+    :param renew_missing: set to `True` if you want the store to
+                          give the user a new sid if the session was
+                          not yet saved.
+    """
+
+    def __init__(
+        self,
+        path=None,
+        filename_template="werkzeug_%s.sess",
+        session_class=None,
+        renew_missing=False,
+        mode=0o644,
+    ):
+        SessionStore.__init__(self, session_class)
+        if path is None:
+            path = tempfile.gettempdir()
+        self.path = path
+        if isinstance(filename_template, text_type) and PY2:
+            filename_template = filename_template.encode(get_filesystem_encoding())
+        assert not filename_template.endswith(_fs_transaction_suffix), (
+            "filename templates may not end with %s" % _fs_transaction_suffix
+        )
+        self.filename_template = filename_template
+        self.renew_missing = renew_missing
+        self.mode = mode
+
+    def get_session_filename(self, sid):
+        # out of the box, this should be a strict ASCII subset but
+        # you might reconfigure the session object to have a more
+        # arbitrary string.
+        if isinstance(sid, text_type) and PY2:
+            sid = sid.encode(get_filesystem_encoding())
+        return path.join(self.path, self.filename_template % sid)
+
+    def save(self, session):
+        fn = self.get_session_filename(session.sid)
+        fd, tmp = tempfile.mkstemp(suffix=_fs_transaction_suffix, dir=self.path)
+        f = os.fdopen(fd, "wb")
+        try:
+            dump(dict(session), f, HIGHEST_PROTOCOL)
+        finally:
+            f.close()
+        try:
+            rename(tmp, fn)
+            os.chmod(fn, self.mode)
+        except (IOError, OSError):
+            pass
+
+    def delete(self, session):
+        fn = self.get_session_filename(session.sid)
+        try:
+            os.unlink(fn)
+        except OSError:
+            pass
+
+    def get(self, sid):
+        if not self.is_valid_key(sid):
+            return self.new()
+        try:
+            f = open(self.get_session_filename(sid), "rb")
+        except IOError:
+            if self.renew_missing:
+                return self.new()
+            data = {}
+        else:
+            try:
+                try:
+                    data = load(f)
+                except Exception:
+                    data = {}
+            finally:
+                f.close()
+        return self.session_class(data, sid, False)
+
+    def list(self):
+        """Lists all sessions in the store.
+
+        .. versionadded:: 0.6
+        """
+        before, after = self.filename_template.split("%s", 1)
+        filename_re = re.compile(
+            r"%s(.{5,})%s$" % (re.escape(before), re.escape(after))
+        )
+        result = []
+        for filename in os.listdir(self.path):
+            #: this is a session that is still being saved.
+            if filename.endswith(_fs_transaction_suffix):
+                continue
+            match = filename_re.match(filename)
+            if match is not None:
+                result.append(match.group(1))
+        return result
+
+
+class SessionMiddleware(object):
+    """A simple middleware that puts the session object of a store provided
+    into the WSGI environ.  It automatically sets cookies and restores
+    sessions.
+
+    However a middleware is not the preferred solution because it won't be as
+    fast as sessions managed by the application itself and will put a key into
+    the WSGI environment only relevant for the application which is against
+    the concept of WSGI.
+
+    The cookie parameters are the same as for the :func:`~dump_cookie`
+    function just prefixed with ``cookie_``.  Additionally `max_age` is
+    called `cookie_age` and not `cookie_max_age` because of backwards
+    compatibility.
+    """
+
+    def __init__(
+        self,
+        app,
+        store,
+        cookie_name="session_id",
+        cookie_age=None,
+        cookie_expires=None,
+        cookie_path="/",
+        cookie_domain=None,
+        cookie_secure=None,
+        cookie_httponly=False,
+        cookie_samesite="Lax",
+        environ_key="werkzeug.session",
+    ):
+        self.app = app
+        self.store = store
+        self.cookie_name = cookie_name
+        self.cookie_age = cookie_age
+        self.cookie_expires = cookie_expires
+        self.cookie_path = cookie_path
+        self.cookie_domain = cookie_domain
+        self.cookie_secure = cookie_secure
+        self.cookie_httponly = cookie_httponly
+        self.cookie_samesite = cookie_samesite
+        self.environ_key = environ_key
+
+    def __call__(self, environ, start_response):
+        cookie = parse_cookie(environ.get("HTTP_COOKIE", ""))
+        sid = cookie.get(self.cookie_name, None)
+        if sid is None:
+            session = self.store.new()
+        else:
+            session = self.store.get(sid)
+        environ[self.environ_key] = session
+
+        def injecting_start_response(status, headers, exc_info=None):
+            if session.should_save:
+                self.store.save(session)
+                headers.append(
+                    (
+                        "Set-Cookie",
+                        dump_cookie(
+                            self.cookie_name,
+                            session.sid,
+                            self.cookie_age,
+                            self.cookie_expires,
+                            self.cookie_path,
+                            self.cookie_domain,
+                            self.cookie_secure,
+                            self.cookie_httponly,
+                            samesite=self.cookie_samesite,
+                        ),
+                    )
+                )
+            return start_response(status, headers, exc_info)
+
+        return ClosingIterator(
+            self.app(environ, injecting_start_response),
+            lambda: self.store.save_if_modified(session),
+        )
diff --git a/python/werkzeug/contrib/wrappers.py b/python/werkzeug/contrib/wrappers.py
new file mode 100644
index 0000000..49b82a7
--- /dev/null
+++ b/python/werkzeug/contrib/wrappers.py
@@ -0,0 +1,385 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.contrib.wrappers
+    ~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Extra wrappers or mixins contributed by the community.  These wrappers can
+    be mixed in into request objects to add extra functionality.
+
+    Example::
+
+        from werkzeug.wrappers import Request as RequestBase
+        from werkzeug.contrib.wrappers import JSONRequestMixin
+
+        class Request(RequestBase, JSONRequestMixin):
+            pass
+
+    Afterwards this request object provides the extra functionality of the
+    :class:`JSONRequestMixin`.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import warnings
+
+from .._compat import wsgi_decoding_dance
+from ..exceptions import BadRequest
+from ..http import dump_options_header
+from ..http import parse_options_header
+from ..utils import cached_property
+from ..wrappers.json import JSONMixin as _JSONMixin
+
+
+def is_known_charset(charset):
+    """Checks if the given charset is known to Python."""
+    try:
+        codecs.lookup(charset)
+    except LookupError:
+        return False
+    return True
+
+
+class JSONRequestMixin(_JSONMixin):
+    """
+    .. deprecated:: 0.15
+        Moved to :class:`werkzeug.wrappers.json.JSONMixin`. This old
+        import will be removed in version 1.0.
+    """
+
+    @property
+    def json(self):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.JSONRequestMixin' has moved to"
+            " 'werkzeug.wrappers.json.JSONMixin'. This old import will"
+            " be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return super(JSONRequestMixin, self).json
+
+
+class ProtobufRequestMixin(object):
+
+    """Add protobuf parsing method to a request object.  This will parse the
+    input data through `protobuf`_ if possible.
+
+    :exc:`~werkzeug.exceptions.BadRequest` will be raised if the content-type
+    is not protobuf or if the data itself cannot be parsed property.
+
+    .. _protobuf: https://github.com/protocolbuffers/protobuf
+
+    .. deprecated:: 0.15
+        This mixin will be removed in version 1.0.
+    """
+
+    #: by default the :class:`ProtobufRequestMixin` will raise a
+    #: :exc:`~werkzeug.exceptions.BadRequest` if the object is not
+    #: initialized.  You can bypass that check by setting this
+    #: attribute to `False`.
+    protobuf_check_initialization = True
+
+    def parse_protobuf(self, proto_type):
+        """Parse the data into an instance of proto_type."""
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.ProtobufRequestMixin' is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        if "protobuf" not in self.environ.get("CONTENT_TYPE", ""):
+            raise BadRequest("Not a Protobuf request")
+
+        obj = proto_type()
+        try:
+            obj.ParseFromString(self.data)
+        except Exception:
+            raise BadRequest("Unable to parse Protobuf request")
+
+        # Fail if not all required fields are set
+        if self.protobuf_check_initialization and not obj.IsInitialized():
+            raise BadRequest("Partial Protobuf request")
+
+        return obj
+
+
+class RoutingArgsRequestMixin(object):
+
+    """This request mixin adds support for the wsgiorg routing args
+    `specification`_.
+
+    .. _specification: https://wsgi.readthedocs.io/en/latest/
+       specifications/routing_args.html
+
+    .. deprecated:: 0.15
+        This mixin will be removed in version 1.0.
+    """
+
+    def _get_routing_args(self):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.RoutingArgsRequestMixin' is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.environ.get("wsgiorg.routing_args", (()))[0]
+
+    def _set_routing_args(self, value):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.RoutingArgsRequestMixin' is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        if self.shallow:
+            raise RuntimeError(
+                "A shallow request tried to modify the WSGI "
+                "environment.  If you really want to do that, "
+                "set `shallow` to False."
+            )
+        self.environ["wsgiorg.routing_args"] = (value, self.routing_vars)
+
+    routing_args = property(
+        _get_routing_args,
+        _set_routing_args,
+        doc="""
+        The positional URL arguments as `tuple`.""",
+    )
+    del _get_routing_args, _set_routing_args
+
+    def _get_routing_vars(self):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.RoutingArgsRequestMixin' is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        rv = self.environ.get("wsgiorg.routing_args")
+        if rv is not None:
+            return rv[1]
+        rv = {}
+        if not self.shallow:
+            self.routing_vars = rv
+        return rv
+
+    def _set_routing_vars(self, value):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.RoutingArgsRequestMixin' is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        if self.shallow:
+            raise RuntimeError(
+                "A shallow request tried to modify the WSGI "
+                "environment.  If you really want to do that, "
+                "set `shallow` to False."
+            )
+        self.environ["wsgiorg.routing_args"] = (self.routing_args, value)
+
+    routing_vars = property(
+        _get_routing_vars,
+        _set_routing_vars,
+        doc="""
+        The keyword URL arguments as `dict`.""",
+    )
+    del _get_routing_vars, _set_routing_vars
+
+
+class ReverseSlashBehaviorRequestMixin(object):
+
+    """This mixin reverses the trailing slash behavior of :attr:`script_root`
+    and :attr:`path`.  This makes it possible to use :func:`~urlparse.urljoin`
+    directly on the paths.
+
+    Because it changes the behavior or :class:`Request` this class has to be
+    mixed in *before* the actual request class::
+
+        class MyRequest(ReverseSlashBehaviorRequestMixin, Request):
+            pass
+
+    This example shows the differences (for an application mounted on
+    `/application` and the request going to `/application/foo/bar`):
+
+        +---------------+-------------------+---------------------+
+        |               | normal behavior   | reverse behavior    |
+        +===============+===================+=====================+
+        | `script_root` | ``/application``  | ``/application/``   |
+        +---------------+-------------------+---------------------+
+        | `path`        | ``/foo/bar``      | ``foo/bar``         |
+        +---------------+-------------------+---------------------+
+
+    .. deprecated:: 0.15
+        This mixin will be removed in version 1.0.
+    """
+
+    @cached_property
+    def path(self):
+        """Requested path as unicode.  This works a bit like the regular path
+        info in the WSGI environment but will not include a leading slash.
+        """
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.ReverseSlashBehaviorRequestMixin'"
+            " is deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        path = wsgi_decoding_dance(
+            self.environ.get("PATH_INFO") or "", self.charset, self.encoding_errors
+        )
+        return path.lstrip("/")
+
+    @cached_property
+    def script_root(self):
+        """The root path of the script includling a trailing slash."""
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.ReverseSlashBehaviorRequestMixin'"
+            " is deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        path = wsgi_decoding_dance(
+            self.environ.get("SCRIPT_NAME") or "", self.charset, self.encoding_errors
+        )
+        return path.rstrip("/") + "/"
+
+
+class DynamicCharsetRequestMixin(object):
+
+    """"If this mixin is mixed into a request class it will provide
+    a dynamic `charset` attribute.  This means that if the charset is
+    transmitted in the content type headers it's used from there.
+
+    Because it changes the behavior or :class:`Request` this class has
+    to be mixed in *before* the actual request class::
+
+        class MyRequest(DynamicCharsetRequestMixin, Request):
+            pass
+
+    By default the request object assumes that the URL charset is the
+    same as the data charset.  If the charset varies on each request
+    based on the transmitted data it's not a good idea to let the URLs
+    change based on that.  Most browsers assume either utf-8 or latin1
+    for the URLs if they have troubles figuring out.  It's strongly
+    recommended to set the URL charset to utf-8::
+
+        class MyRequest(DynamicCharsetRequestMixin, Request):
+            url_charset = 'utf-8'
+
+    .. deprecated:: 0.15
+        This mixin will be removed in version 1.0.
+
+    .. versionadded:: 0.6
+    """
+
+    #: the default charset that is assumed if the content type header
+    #: is missing or does not contain a charset parameter.  The default
+    #: is latin1 which is what HTTP specifies as default charset.
+    #: You may however want to set this to utf-8 to better support
+    #: browsers that do not transmit a charset for incoming data.
+    default_charset = "latin1"
+
+    def unknown_charset(self, charset):
+        """Called if a charset was provided but is not supported by
+        the Python codecs module.  By default latin1 is assumed then
+        to not lose any information, you may override this method to
+        change the behavior.
+
+        :param charset: the charset that was not found.
+        :return: the replacement charset.
+        """
+        return "latin1"
+
+    @cached_property
+    def charset(self):
+        """The charset from the content type."""
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.DynamicCharsetRequestMixin'"
+            " is deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        header = self.environ.get("CONTENT_TYPE")
+        if header:
+            ct, options = parse_options_header(header)
+            charset = options.get("charset")
+            if charset:
+                if is_known_charset(charset):
+                    return charset
+                return self.unknown_charset(charset)
+        return self.default_charset
+
+
+class DynamicCharsetResponseMixin(object):
+
+    """If this mixin is mixed into a response class it will provide
+    a dynamic `charset` attribute.  This means that if the charset is
+    looked up and stored in the `Content-Type` header and updates
+    itself automatically.  This also means a small performance hit but
+    can be useful if you're working with different charsets on
+    responses.
+
+    Because the charset attribute is no a property at class-level, the
+    default value is stored in `default_charset`.
+
+    Because it changes the behavior or :class:`Response` this class has
+    to be mixed in *before* the actual response class::
+
+        class MyResponse(DynamicCharsetResponseMixin, Response):
+            pass
+
+    .. deprecated:: 0.15
+        This mixin will be removed in version 1.0.
+
+    .. versionadded:: 0.6
+    """
+
+    #: the default charset.
+    default_charset = "utf-8"
+
+    def _get_charset(self):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.DynamicCharsetResponseMixin'"
+            " is deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        header = self.headers.get("content-type")
+        if header:
+            charset = parse_options_header(header)[1].get("charset")
+            if charset:
+                return charset
+        return self.default_charset
+
+    def _set_charset(self, charset):
+        warnings.warn(
+            "'werkzeug.contrib.wrappers.DynamicCharsetResponseMixin'"
+            " is deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        header = self.headers.get("content-type")
+        ct, options = parse_options_header(header)
+        if not ct:
+            raise TypeError("Cannot set charset if Content-Type header is missing.")
+        options["charset"] = charset
+        self.headers["Content-Type"] = dump_options_header(ct, options)
+
+    charset = property(
+        _get_charset,
+        _set_charset,
+        doc="""
+        The charset for the response.  It's stored inside the
+        Content-Type header as a parameter.""",
+    )
+    del _get_charset, _set_charset
diff --git a/python/werkzeug/datastructures.py b/python/werkzeug/datastructures.py
new file mode 100644
index 0000000..9643db9
--- /dev/null
+++ b/python/werkzeug/datastructures.py
@@ -0,0 +1,2852 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.datastructures
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    This module provides mixins and classes with an immutable interface.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import mimetypes
+import re
+from copy import deepcopy
+from itertools import repeat
+
+from ._compat import BytesIO
+from ._compat import collections_abc
+from ._compat import integer_types
+from ._compat import iteritems
+from ._compat import iterkeys
+from ._compat import iterlists
+from ._compat import itervalues
+from ._compat import make_literal_wrapper
+from ._compat import PY2
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import to_native
+from ._internal import _missing
+from .filesystem import get_filesystem_encoding
+
+_locale_delim_re = re.compile(r"[_-]")
+
+
+def is_immutable(self):
+    raise TypeError("%r objects are immutable" % self.__class__.__name__)
+
+
+def iter_multi_items(mapping):
+    """Iterates over the items of a mapping yielding keys and values
+    without dropping any from more complex structures.
+    """
+    if isinstance(mapping, MultiDict):
+        for item in iteritems(mapping, multi=True):
+            yield item
+    elif isinstance(mapping, dict):
+        for key, value in iteritems(mapping):
+            if isinstance(value, (tuple, list)):
+                for value in value:
+                    yield key, value
+            else:
+                yield key, value
+    else:
+        for item in mapping:
+            yield item
+
+
+def native_itermethods(names):
+    if not PY2:
+        return lambda x: x
+
+    def setviewmethod(cls, name):
+        viewmethod_name = "view%s" % name
+        repr_name = "view_%s" % name
+
+        def viewmethod(self, *a, **kw):
+            return ViewItems(self, name, repr_name, *a, **kw)
+
+        viewmethod.__name__ = viewmethod_name
+        viewmethod.__doc__ = "`%s()` object providing a view on %s" % (
+            viewmethod_name,
+            name,
+        )
+        setattr(cls, viewmethod_name, viewmethod)
+
+    def setitermethod(cls, name):
+        itermethod = getattr(cls, name)
+        setattr(cls, "iter%s" % name, itermethod)
+
+        def listmethod(self, *a, **kw):
+            return list(itermethod(self, *a, **kw))
+
+        listmethod.__name__ = name
+        listmethod.__doc__ = "Like :py:meth:`iter%s`, but returns a list." % name
+        setattr(cls, name, listmethod)
+
+    def wrap(cls):
+        for name in names:
+            setitermethod(cls, name)
+            setviewmethod(cls, name)
+        return cls
+
+    return wrap
+
+
+class ImmutableListMixin(object):
+    """Makes a :class:`list` immutable.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    _hash_cache = None
+
+    def __hash__(self):
+        if self._hash_cache is not None:
+            return self._hash_cache
+        rv = self._hash_cache = hash(tuple(self))
+        return rv
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (list(self),)
+
+    def __delitem__(self, key):
+        is_immutable(self)
+
+    def __iadd__(self, other):
+        is_immutable(self)
+
+    __imul__ = __iadd__
+
+    def __setitem__(self, key, value):
+        is_immutable(self)
+
+    def append(self, item):
+        is_immutable(self)
+
+    remove = append
+
+    def extend(self, iterable):
+        is_immutable(self)
+
+    def insert(self, pos, value):
+        is_immutable(self)
+
+    def pop(self, index=-1):
+        is_immutable(self)
+
+    def reverse(self):
+        is_immutable(self)
+
+    def sort(self, cmp=None, key=None, reverse=None):
+        is_immutable(self)
+
+
+class ImmutableList(ImmutableListMixin, list):
+    """An immutable :class:`list`.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, list.__repr__(self))
+
+
+class ImmutableDictMixin(object):
+    """Makes a :class:`dict` immutable.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    _hash_cache = None
+
+    @classmethod
+    def fromkeys(cls, keys, value=None):
+        instance = super(cls, cls).__new__(cls)
+        instance.__init__(zip(keys, repeat(value)))
+        return instance
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (dict(self),)
+
+    def _iter_hashitems(self):
+        return iteritems(self)
+
+    def __hash__(self):
+        if self._hash_cache is not None:
+            return self._hash_cache
+        rv = self._hash_cache = hash(frozenset(self._iter_hashitems()))
+        return rv
+
+    def setdefault(self, key, default=None):
+        is_immutable(self)
+
+    def update(self, *args, **kwargs):
+        is_immutable(self)
+
+    def pop(self, key, default=None):
+        is_immutable(self)
+
+    def popitem(self):
+        is_immutable(self)
+
+    def __setitem__(self, key, value):
+        is_immutable(self)
+
+    def __delitem__(self, key):
+        is_immutable(self)
+
+    def clear(self):
+        is_immutable(self)
+
+
+class ImmutableMultiDictMixin(ImmutableDictMixin):
+    """Makes a :class:`MultiDict` immutable.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (list(iteritems(self, multi=True)),)
+
+    def _iter_hashitems(self):
+        return iteritems(self, multi=True)
+
+    def add(self, key, value):
+        is_immutable(self)
+
+    def popitemlist(self):
+        is_immutable(self)
+
+    def poplist(self, key):
+        is_immutable(self)
+
+    def setlist(self, key, new_list):
+        is_immutable(self)
+
+    def setlistdefault(self, key, default_list=None):
+        is_immutable(self)
+
+
+class UpdateDictMixin(object):
+    """Makes dicts call `self.on_update` on modifications.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    on_update = None
+
+    def calls_update(name):  # noqa: B902
+        def oncall(self, *args, **kw):
+            rv = getattr(super(UpdateDictMixin, self), name)(*args, **kw)
+            if self.on_update is not None:
+                self.on_update(self)
+            return rv
+
+        oncall.__name__ = name
+        return oncall
+
+    def setdefault(self, key, default=None):
+        modified = key not in self
+        rv = super(UpdateDictMixin, self).setdefault(key, default)
+        if modified and self.on_update is not None:
+            self.on_update(self)
+        return rv
+
+    def pop(self, key, default=_missing):
+        modified = key in self
+        if default is _missing:
+            rv = super(UpdateDictMixin, self).pop(key)
+        else:
+            rv = super(UpdateDictMixin, self).pop(key, default)
+        if modified and self.on_update is not None:
+            self.on_update(self)
+        return rv
+
+    __setitem__ = calls_update("__setitem__")
+    __delitem__ = calls_update("__delitem__")
+    clear = calls_update("clear")
+    popitem = calls_update("popitem")
+    update = calls_update("update")
+    del calls_update
+
+
+class TypeConversionDict(dict):
+    """Works like a regular dict but the :meth:`get` method can perform
+    type conversions.  :class:`MultiDict` and :class:`CombinedMultiDict`
+    are subclasses of this class and provide the same feature.
+
+    .. versionadded:: 0.5
+    """
+
+    def get(self, key, default=None, type=None):
+        """Return the default value if the requested data doesn't exist.
+        If `type` is provided and is a callable it should convert the value,
+        return it or raise a :exc:`ValueError` if that is not possible.  In
+        this case the function will return the default as if the value was not
+        found:
+
+        >>> d = TypeConversionDict(foo='42', bar='blub')
+        >>> d.get('foo', type=int)
+        42
+        >>> d.get('bar', -1, type=int)
+        -1
+
+        :param key: The key to be looked up.
+        :param default: The default value to be returned if the key can't
+                        be looked up.  If not further specified `None` is
+                        returned.
+        :param type: A callable that is used to cast the value in the
+                     :class:`MultiDict`.  If a :exc:`ValueError` is raised
+                     by this callable the default value is returned.
+        """
+        try:
+            rv = self[key]
+        except KeyError:
+            return default
+        if type is not None:
+            try:
+                rv = type(rv)
+            except ValueError:
+                rv = default
+        return rv
+
+
+class ImmutableTypeConversionDict(ImmutableDictMixin, TypeConversionDict):
+    """Works like a :class:`TypeConversionDict` but does not support
+    modifications.
+
+    .. versionadded:: 0.5
+    """
+
+    def copy(self):
+        """Return a shallow mutable copy of this object.  Keep in mind that
+        the standard library's :func:`copy` function is a no-op for this class
+        like for any other python immutable type (eg: :class:`tuple`).
+        """
+        return TypeConversionDict(self)
+
+    def __copy__(self):
+        return self
+
+
+class ViewItems(object):
+    def __init__(self, multi_dict, method, repr_name, *a, **kw):
+        self.__multi_dict = multi_dict
+        self.__method = method
+        self.__repr_name = repr_name
+        self.__a = a
+        self.__kw = kw
+
+    def __get_items(self):
+        return getattr(self.__multi_dict, self.__method)(*self.__a, **self.__kw)
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__repr_name, list(self.__get_items()))
+
+    def __iter__(self):
+        return iter(self.__get_items())
+
+
+@native_itermethods(["keys", "values", "items", "lists", "listvalues"])
+class MultiDict(TypeConversionDict):
+    """A :class:`MultiDict` is a dictionary subclass customized to deal with
+    multiple values for the same key which is for example used by the parsing
+    functions in the wrappers.  This is necessary because some HTML form
+    elements pass multiple values for the same key.
+
+    :class:`MultiDict` implements all standard dictionary methods.
+    Internally, it saves all values for a key as a list, but the standard dict
+    access methods will only return the first value for a key. If you want to
+    gain access to the other values, too, you have to use the `list` methods as
+    explained below.
+
+    Basic Usage:
+
+    >>> d = MultiDict([('a', 'b'), ('a', 'c')])
+    >>> d
+    MultiDict([('a', 'b'), ('a', 'c')])
+    >>> d['a']
+    'b'
+    >>> d.getlist('a')
+    ['b', 'c']
+    >>> 'a' in d
+    True
+
+    It behaves like a normal dict thus all dict functions will only return the
+    first value when multiple values for one key are found.
+
+    From Werkzeug 0.3 onwards, the `KeyError` raised by this class is also a
+    subclass of the :exc:`~exceptions.BadRequest` HTTP exception and will
+    render a page for a ``400 BAD REQUEST`` if caught in a catch-all for HTTP
+    exceptions.
+
+    A :class:`MultiDict` can be constructed from an iterable of
+    ``(key, value)`` tuples, a dict, a :class:`MultiDict` or from Werkzeug 0.2
+    onwards some keyword parameters.
+
+    :param mapping: the initial value for the :class:`MultiDict`.  Either a
+                    regular dict, an iterable of ``(key, value)`` tuples
+                    or `None`.
+    """
+
+    def __init__(self, mapping=None):
+        if isinstance(mapping, MultiDict):
+            dict.__init__(self, ((k, l[:]) for k, l in iterlists(mapping)))
+        elif isinstance(mapping, dict):
+            tmp = {}
+            for key, value in iteritems(mapping):
+                if isinstance(value, (tuple, list)):
+                    if len(value) == 0:
+                        continue
+                    value = list(value)
+                else:
+                    value = [value]
+                tmp[key] = value
+            dict.__init__(self, tmp)
+        else:
+            tmp = {}
+            for key, value in mapping or ():
+                tmp.setdefault(key, []).append(value)
+            dict.__init__(self, tmp)
+
+    def __getstate__(self):
+        return dict(self.lists())
+
+    def __setstate__(self, value):
+        dict.clear(self)
+        dict.update(self, value)
+
+    def __getitem__(self, key):
+        """Return the first data value for this key;
+        raises KeyError if not found.
+
+        :param key: The key to be looked up.
+        :raise KeyError: if the key does not exist.
+        """
+
+        if key in self:
+            lst = dict.__getitem__(self, key)
+            if len(lst) > 0:
+                return lst[0]
+        raise exceptions.BadRequestKeyError(key)
+
+    def __setitem__(self, key, value):
+        """Like :meth:`add` but removes an existing key first.
+
+        :param key: the key for the value.
+        :param value: the value to set.
+        """
+        dict.__setitem__(self, key, [value])
+
+    def add(self, key, value):
+        """Adds a new value for the key.
+
+        .. versionadded:: 0.6
+
+        :param key: the key for the value.
+        :param value: the value to add.
+        """
+        dict.setdefault(self, key, []).append(value)
+
+    def getlist(self, key, type=None):
+        """Return the list of items for a given key. If that key is not in the
+        `MultiDict`, the return value will be an empty list.  Just as `get`
+        `getlist` accepts a `type` parameter.  All items will be converted
+        with the callable defined there.
+
+        :param key: The key to be looked up.
+        :param type: A callable that is used to cast the value in the
+                     :class:`MultiDict`.  If a :exc:`ValueError` is raised
+                     by this callable the value will be removed from the list.
+        :return: a :class:`list` of all the values for the key.
+        """
+        try:
+            rv = dict.__getitem__(self, key)
+        except KeyError:
+            return []
+        if type is None:
+            return list(rv)
+        result = []
+        for item in rv:
+            try:
+                result.append(type(item))
+            except ValueError:
+                pass
+        return result
+
+    def setlist(self, key, new_list):
+        """Remove the old values for a key and add new ones.  Note that the list
+        you pass the values in will be shallow-copied before it is inserted in
+        the dictionary.
+
+        >>> d = MultiDict()
+        >>> d.setlist('foo', ['1', '2'])
+        >>> d['foo']
+        '1'
+        >>> d.getlist('foo')
+        ['1', '2']
+
+        :param key: The key for which the values are set.
+        :param new_list: An iterable with the new values for the key.  Old values
+                         are removed first.
+        """
+        dict.__setitem__(self, key, list(new_list))
+
+    def setdefault(self, key, default=None):
+        """Returns the value for the key if it is in the dict, otherwise it
+        returns `default` and sets that value for `key`.
+
+        :param key: The key to be looked up.
+        :param default: The default value to be returned if the key is not
+                        in the dict.  If not further specified it's `None`.
+        """
+        if key not in self:
+            self[key] = default
+        else:
+            default = self[key]
+        return default
+
+    def setlistdefault(self, key, default_list=None):
+        """Like `setdefault` but sets multiple values.  The list returned
+        is not a copy, but the list that is actually used internally.  This
+        means that you can put new values into the dict by appending items
+        to the list:
+
+        >>> d = MultiDict({"foo": 1})
+        >>> d.setlistdefault("foo").extend([2, 3])
+        >>> d.getlist("foo")
+        [1, 2, 3]
+
+        :param key: The key to be looked up.
+        :param default_list: An iterable of default values.  It is either copied
+                             (in case it was a list) or converted into a list
+                             before returned.
+        :return: a :class:`list`
+        """
+        if key not in self:
+            default_list = list(default_list or ())
+            dict.__setitem__(self, key, default_list)
+        else:
+            default_list = dict.__getitem__(self, key)
+        return default_list
+
+    def items(self, multi=False):
+        """Return an iterator of ``(key, value)`` pairs.
+
+        :param multi: If set to `True` the iterator returned will have a pair
+                      for each value of each key.  Otherwise it will only
+                      contain pairs for the first value of each key.
+        """
+
+        for key, values in iteritems(dict, self):
+            if multi:
+                for value in values:
+                    yield key, value
+            else:
+                yield key, values[0]
+
+    def lists(self):
+        """Return a iterator of ``(key, values)`` pairs, where values is the list
+        of all values associated with the key."""
+
+        for key, values in iteritems(dict, self):
+            yield key, list(values)
+
+    def keys(self):
+        return iterkeys(dict, self)
+
+    __iter__ = keys
+
+    def values(self):
+        """Returns an iterator of the first value on every key's value list."""
+        for values in itervalues(dict, self):
+            yield values[0]
+
+    def listvalues(self):
+        """Return an iterator of all values associated with a key.  Zipping
+        :meth:`keys` and this is the same as calling :meth:`lists`:
+
+        >>> d = MultiDict({"foo": [1, 2, 3]})
+        >>> zip(d.keys(), d.listvalues()) == d.lists()
+        True
+        """
+
+        return itervalues(dict, self)
+
+    def copy(self):
+        """Return a shallow copy of this object."""
+        return self.__class__(self)
+
+    def deepcopy(self, memo=None):
+        """Return a deep copy of this object."""
+        return self.__class__(deepcopy(self.to_dict(flat=False), memo))
+
+    def to_dict(self, flat=True):
+        """Return the contents as regular dict.  If `flat` is `True` the
+        returned dict will only have the first item present, if `flat` is
+        `False` all values will be returned as lists.
+
+        :param flat: If set to `False` the dict returned will have lists
+                     with all the values in it.  Otherwise it will only
+                     contain the first value for each key.
+        :return: a :class:`dict`
+        """
+        if flat:
+            return dict(iteritems(self))
+        return dict(self.lists())
+
+    def update(self, other_dict):
+        """update() extends rather than replaces existing key lists:
+
+        >>> a = MultiDict({'x': 1})
+        >>> b = MultiDict({'x': 2, 'y': 3})
+        >>> a.update(b)
+        >>> a
+        MultiDict([('y', 3), ('x', 1), ('x', 2)])
+
+        If the value list for a key in ``other_dict`` is empty, no new values
+        will be added to the dict and the key will not be created:
+
+        >>> x = {'empty_list': []}
+        >>> y = MultiDict()
+        >>> y.update(x)
+        >>> y
+        MultiDict([])
+        """
+        for key, value in iter_multi_items(other_dict):
+            MultiDict.add(self, key, value)
+
+    def pop(self, key, default=_missing):
+        """Pop the first item for a list on the dict.  Afterwards the
+        key is removed from the dict, so additional values are discarded:
+
+        >>> d = MultiDict({"foo": [1, 2, 3]})
+        >>> d.pop("foo")
+        1
+        >>> "foo" in d
+        False
+
+        :param key: the key to pop.
+        :param default: if provided the value to return if the key was
+                        not in the dictionary.
+        """
+        try:
+            lst = dict.pop(self, key)
+
+            if len(lst) == 0:
+                raise exceptions.BadRequestKeyError(key)
+
+            return lst[0]
+        except KeyError:
+            if default is not _missing:
+                return default
+            raise exceptions.BadRequestKeyError(key)
+
+    def popitem(self):
+        """Pop an item from the dict."""
+        try:
+            item = dict.popitem(self)
+
+            if len(item[1]) == 0:
+                raise exceptions.BadRequestKeyError(item)
+
+            return (item[0], item[1][0])
+        except KeyError as e:
+            raise exceptions.BadRequestKeyError(e.args[0])
+
+    def poplist(self, key):
+        """Pop the list for a key from the dict.  If the key is not in the dict
+        an empty list is returned.
+
+        .. versionchanged:: 0.5
+           If the key does no longer exist a list is returned instead of
+           raising an error.
+        """
+        return dict.pop(self, key, [])
+
+    def popitemlist(self):
+        """Pop a ``(key, list)`` tuple from the dict."""
+        try:
+            return dict.popitem(self)
+        except KeyError as e:
+            raise exceptions.BadRequestKeyError(e.args[0])
+
+    def __copy__(self):
+        return self.copy()
+
+    def __deepcopy__(self, memo):
+        return self.deepcopy(memo=memo)
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, list(iteritems(self, multi=True)))
+
+
+class _omd_bucket(object):
+    """Wraps values in the :class:`OrderedMultiDict`.  This makes it
+    possible to keep an order over multiple different keys.  It requires
+    a lot of extra memory and slows down access a lot, but makes it
+    possible to access elements in O(1) and iterate in O(n).
+    """
+
+    __slots__ = ("prev", "key", "value", "next")
+
+    def __init__(self, omd, key, value):
+        self.prev = omd._last_bucket
+        self.key = key
+        self.value = value
+        self.next = None
+
+        if omd._first_bucket is None:
+            omd._first_bucket = self
+        if omd._last_bucket is not None:
+            omd._last_bucket.next = self
+        omd._last_bucket = self
+
+    def unlink(self, omd):
+        if self.prev:
+            self.prev.next = self.next
+        if self.next:
+            self.next.prev = self.prev
+        if omd._first_bucket is self:
+            omd._first_bucket = self.next
+        if omd._last_bucket is self:
+            omd._last_bucket = self.prev
+
+
+@native_itermethods(["keys", "values", "items", "lists", "listvalues"])
+class OrderedMultiDict(MultiDict):
+    """Works like a regular :class:`MultiDict` but preserves the
+    order of the fields.  To convert the ordered multi dict into a
+    list you can use the :meth:`items` method and pass it ``multi=True``.
+
+    In general an :class:`OrderedMultiDict` is an order of magnitude
+    slower than a :class:`MultiDict`.
+
+    .. admonition:: note
+
+       Due to a limitation in Python you cannot convert an ordered
+       multi dict into a regular dict by using ``dict(multidict)``.
+       Instead you have to use the :meth:`to_dict` method, otherwise
+       the internal bucket objects are exposed.
+    """
+
+    def __init__(self, mapping=None):
+        dict.__init__(self)
+        self._first_bucket = self._last_bucket = None
+        if mapping is not None:
+            OrderedMultiDict.update(self, mapping)
+
+    def __eq__(self, other):
+        if not isinstance(other, MultiDict):
+            return NotImplemented
+        if isinstance(other, OrderedMultiDict):
+            iter1 = iteritems(self, multi=True)
+            iter2 = iteritems(other, multi=True)
+            try:
+                for k1, v1 in iter1:
+                    k2, v2 = next(iter2)
+                    if k1 != k2 or v1 != v2:
+                        return False
+            except StopIteration:
+                return False
+            try:
+                next(iter2)
+            except StopIteration:
+                return True
+            return False
+        if len(self) != len(other):
+            return False
+        for key, values in iterlists(self):
+            if other.getlist(key) != values:
+                return False
+        return True
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (list(iteritems(self, multi=True)),)
+
+    def __getstate__(self):
+        return list(iteritems(self, multi=True))
+
+    def __setstate__(self, values):
+        dict.clear(self)
+        for key, value in values:
+            self.add(key, value)
+
+    def __getitem__(self, key):
+        if key in self:
+            return dict.__getitem__(self, key)[0].value
+        raise exceptions.BadRequestKeyError(key)
+
+    def __setitem__(self, key, value):
+        self.poplist(key)
+        self.add(key, value)
+
+    def __delitem__(self, key):
+        self.pop(key)
+
+    def keys(self):
+        return (key for key, value in iteritems(self))
+
+    __iter__ = keys
+
+    def values(self):
+        return (value for key, value in iteritems(self))
+
+    def items(self, multi=False):
+        ptr = self._first_bucket
+        if multi:
+            while ptr is not None:
+                yield ptr.key, ptr.value
+                ptr = ptr.next
+        else:
+            returned_keys = set()
+            while ptr is not None:
+                if ptr.key not in returned_keys:
+                    returned_keys.add(ptr.key)
+                    yield ptr.key, ptr.value
+                ptr = ptr.next
+
+    def lists(self):
+        returned_keys = set()
+        ptr = self._first_bucket
+        while ptr is not None:
+            if ptr.key not in returned_keys:
+                yield ptr.key, self.getlist(ptr.key)
+                returned_keys.add(ptr.key)
+            ptr = ptr.next
+
+    def listvalues(self):
+        for _key, values in iterlists(self):
+            yield values
+
+    def add(self, key, value):
+        dict.setdefault(self, key, []).append(_omd_bucket(self, key, value))
+
+    def getlist(self, key, type=None):
+        try:
+            rv = dict.__getitem__(self, key)
+        except KeyError:
+            return []
+        if type is None:
+            return [x.value for x in rv]
+        result = []
+        for item in rv:
+            try:
+                result.append(type(item.value))
+            except ValueError:
+                pass
+        return result
+
+    def setlist(self, key, new_list):
+        self.poplist(key)
+        for value in new_list:
+            self.add(key, value)
+
+    def setlistdefault(self, key, default_list=None):
+        raise TypeError("setlistdefault is unsupported for ordered multi dicts")
+
+    def update(self, mapping):
+        for key, value in iter_multi_items(mapping):
+            OrderedMultiDict.add(self, key, value)
+
+    def poplist(self, key):
+        buckets = dict.pop(self, key, ())
+        for bucket in buckets:
+            bucket.unlink(self)
+        return [x.value for x in buckets]
+
+    def pop(self, key, default=_missing):
+        try:
+            buckets = dict.pop(self, key)
+        except KeyError:
+            if default is not _missing:
+                return default
+            raise exceptions.BadRequestKeyError(key)
+        for bucket in buckets:
+            bucket.unlink(self)
+        return buckets[0].value
+
+    def popitem(self):
+        try:
+            key, buckets = dict.popitem(self)
+        except KeyError as e:
+            raise exceptions.BadRequestKeyError(e.args[0])
+        for bucket in buckets:
+            bucket.unlink(self)
+        return key, buckets[0].value
+
+    def popitemlist(self):
+        try:
+            key, buckets = dict.popitem(self)
+        except KeyError as e:
+            raise exceptions.BadRequestKeyError(e.args[0])
+        for bucket in buckets:
+            bucket.unlink(self)
+        return key, [x.value for x in buckets]
+
+
+def _options_header_vkw(value, kw):
+    return dump_options_header(
+        value, dict((k.replace("_", "-"), v) for k, v in kw.items())
+    )
+
+
+def _unicodify_header_value(value):
+    if isinstance(value, bytes):
+        value = value.decode("latin-1")
+    if not isinstance(value, text_type):
+        value = text_type(value)
+    return value
+
+
+@native_itermethods(["keys", "values", "items"])
+class Headers(object):
+    """An object that stores some headers.  It has a dict-like interface
+    but is ordered and can store the same keys multiple times.
+
+    This data structure is useful if you want a nicer way to handle WSGI
+    headers which are stored as tuples in a list.
+
+    From Werkzeug 0.3 onwards, the :exc:`KeyError` raised by this class is
+    also a subclass of the :class:`~exceptions.BadRequest` HTTP exception
+    and will render a page for a ``400 BAD REQUEST`` if caught in a
+    catch-all for HTTP exceptions.
+
+    Headers is mostly compatible with the Python :class:`wsgiref.headers.Headers`
+    class, with the exception of `__getitem__`.  :mod:`wsgiref` will return
+    `None` for ``headers['missing']``, whereas :class:`Headers` will raise
+    a :class:`KeyError`.
+
+    To create a new :class:`Headers` object pass it a list or dict of headers
+    which are used as default values.  This does not reuse the list passed
+    to the constructor for internal usage.
+
+    :param defaults: The list of default values for the :class:`Headers`.
+
+    .. versionchanged:: 0.9
+       This data structure now stores unicode values similar to how the
+       multi dicts do it.  The main difference is that bytes can be set as
+       well which will automatically be latin1 decoded.
+
+    .. versionchanged:: 0.9
+       The :meth:`linked` function was removed without replacement as it
+       was an API that does not support the changes to the encoding model.
+    """
+
+    def __init__(self, defaults=None):
+        self._list = []
+        if defaults is not None:
+            if isinstance(defaults, (list, Headers)):
+                self._list.extend(defaults)
+            else:
+                self.extend(defaults)
+
+    def __getitem__(self, key, _get_mode=False):
+        if not _get_mode:
+            if isinstance(key, integer_types):
+                return self._list[key]
+            elif isinstance(key, slice):
+                return self.__class__(self._list[key])
+        if not isinstance(key, string_types):
+            raise exceptions.BadRequestKeyError(key)
+        ikey = key.lower()
+        for k, v in self._list:
+            if k.lower() == ikey:
+                return v
+        # micro optimization: if we are in get mode we will catch that
+        # exception one stack level down so we can raise a standard
+        # key error instead of our special one.
+        if _get_mode:
+            raise KeyError()
+        raise exceptions.BadRequestKeyError(key)
+
+    def __eq__(self, other):
+        return other.__class__ is self.__class__ and set(other._list) == set(self._list)
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def get(self, key, default=None, type=None, as_bytes=False):
+        """Return the default value if the requested data doesn't exist.
+        If `type` is provided and is a callable it should convert the value,
+        return it or raise a :exc:`ValueError` if that is not possible.  In
+        this case the function will return the default as if the value was not
+        found:
+
+        >>> d = Headers([('Content-Length', '42')])
+        >>> d.get('Content-Length', type=int)
+        42
+
+        If a headers object is bound you must not add unicode strings
+        because no encoding takes place.
+
+        .. versionadded:: 0.9
+           Added support for `as_bytes`.
+
+        :param key: The key to be looked up.
+        :param default: The default value to be returned if the key can't
+                        be looked up.  If not further specified `None` is
+                        returned.
+        :param type: A callable that is used to cast the value in the
+                     :class:`Headers`.  If a :exc:`ValueError` is raised
+                     by this callable the default value is returned.
+        :param as_bytes: return bytes instead of unicode strings.
+        """
+        try:
+            rv = self.__getitem__(key, _get_mode=True)
+        except KeyError:
+            return default
+        if as_bytes:
+            rv = rv.encode("latin1")
+        if type is None:
+            return rv
+        try:
+            return type(rv)
+        except ValueError:
+            return default
+
+    def getlist(self, key, type=None, as_bytes=False):
+        """Return the list of items for a given key. If that key is not in the
+        :class:`Headers`, the return value will be an empty list.  Just as
+        :meth:`get` :meth:`getlist` accepts a `type` parameter.  All items will
+        be converted with the callable defined there.
+
+        .. versionadded:: 0.9
+           Added support for `as_bytes`.
+
+        :param key: The key to be looked up.
+        :param type: A callable that is used to cast the value in the
+                     :class:`Headers`.  If a :exc:`ValueError` is raised
+                     by this callable the value will be removed from the list.
+        :return: a :class:`list` of all the values for the key.
+        :param as_bytes: return bytes instead of unicode strings.
+        """
+        ikey = key.lower()
+        result = []
+        for k, v in self:
+            if k.lower() == ikey:
+                if as_bytes:
+                    v = v.encode("latin1")
+                if type is not None:
+                    try:
+                        v = type(v)
+                    except ValueError:
+                        continue
+                result.append(v)
+        return result
+
+    def get_all(self, name):
+        """Return a list of all the values for the named field.
+
+        This method is compatible with the :mod:`wsgiref`
+        :meth:`~wsgiref.headers.Headers.get_all` method.
+        """
+        return self.getlist(name)
+
+    def items(self, lower=False):
+        for key, value in self:
+            if lower:
+                key = key.lower()
+            yield key, value
+
+    def keys(self, lower=False):
+        for key, _ in iteritems(self, lower):
+            yield key
+
+    def values(self):
+        for _, value in iteritems(self):
+            yield value
+
+    def extend(self, iterable):
+        """Extend the headers with a dict or an iterable yielding keys and
+        values.
+        """
+        if isinstance(iterable, dict):
+            for key, value in iteritems(iterable):
+                if isinstance(value, (tuple, list)):
+                    for v in value:
+                        self.add(key, v)
+                else:
+                    self.add(key, value)
+        else:
+            for key, value in iterable:
+                self.add(key, value)
+
+    def __delitem__(self, key, _index_operation=True):
+        if _index_operation and isinstance(key, (integer_types, slice)):
+            del self._list[key]
+            return
+        key = key.lower()
+        new = []
+        for k, v in self._list:
+            if k.lower() != key:
+                new.append((k, v))
+        self._list[:] = new
+
+    def remove(self, key):
+        """Remove a key.
+
+        :param key: The key to be removed.
+        """
+        return self.__delitem__(key, _index_operation=False)
+
+    def pop(self, key=None, default=_missing):
+        """Removes and returns a key or index.
+
+        :param key: The key to be popped.  If this is an integer the item at
+                    that position is removed, if it's a string the value for
+                    that key is.  If the key is omitted or `None` the last
+                    item is removed.
+        :return: an item.
+        """
+        if key is None:
+            return self._list.pop()
+        if isinstance(key, integer_types):
+            return self._list.pop(key)
+        try:
+            rv = self[key]
+            self.remove(key)
+        except KeyError:
+            if default is not _missing:
+                return default
+            raise
+        return rv
+
+    def popitem(self):
+        """Removes a key or index and returns a (key, value) item."""
+        return self.pop()
+
+    def __contains__(self, key):
+        """Check if a key is present."""
+        try:
+            self.__getitem__(key, _get_mode=True)
+        except KeyError:
+            return False
+        return True
+
+    has_key = __contains__
+
+    def __iter__(self):
+        """Yield ``(key, value)`` tuples."""
+        return iter(self._list)
+
+    def __len__(self):
+        return len(self._list)
+
+    def add(self, _key, _value, **kw):
+        """Add a new header tuple to the list.
+
+        Keyword arguments can specify additional parameters for the header
+        value, with underscores converted to dashes::
+
+        >>> d = Headers()
+        >>> d.add('Content-Type', 'text/plain')
+        >>> d.add('Content-Disposition', 'attachment', filename='foo.png')
+
+        The keyword argument dumping uses :func:`dump_options_header`
+        behind the scenes.
+
+        .. versionadded:: 0.4.1
+            keyword arguments were added for :mod:`wsgiref` compatibility.
+        """
+        if kw:
+            _value = _options_header_vkw(_value, kw)
+        _key = _unicodify_header_value(_key)
+        _value = _unicodify_header_value(_value)
+        self._validate_value(_value)
+        self._list.append((_key, _value))
+
+    def _validate_value(self, value):
+        if not isinstance(value, text_type):
+            raise TypeError("Value should be unicode.")
+        if u"\n" in value or u"\r" in value:
+            raise ValueError(
+                "Detected newline in header value.  This is "
+                "a potential security problem"
+            )
+
+    def add_header(self, _key, _value, **_kw):
+        """Add a new header tuple to the list.
+
+        An alias for :meth:`add` for compatibility with the :mod:`wsgiref`
+        :meth:`~wsgiref.headers.Headers.add_header` method.
+        """
+        self.add(_key, _value, **_kw)
+
+    def clear(self):
+        """Clears all headers."""
+        del self._list[:]
+
+    def set(self, _key, _value, **kw):
+        """Remove all header tuples for `key` and add a new one.  The newly
+        added key either appears at the end of the list if there was no
+        entry or replaces the first one.
+
+        Keyword arguments can specify additional parameters for the header
+        value, with underscores converted to dashes.  See :meth:`add` for
+        more information.
+
+        .. versionchanged:: 0.6.1
+           :meth:`set` now accepts the same arguments as :meth:`add`.
+
+        :param key: The key to be inserted.
+        :param value: The value to be inserted.
+        """
+        if kw:
+            _value = _options_header_vkw(_value, kw)
+        _key = _unicodify_header_value(_key)
+        _value = _unicodify_header_value(_value)
+        self._validate_value(_value)
+        if not self._list:
+            self._list.append((_key, _value))
+            return
+        listiter = iter(self._list)
+        ikey = _key.lower()
+        for idx, (old_key, _old_value) in enumerate(listiter):
+            if old_key.lower() == ikey:
+                # replace first ocurrence
+                self._list[idx] = (_key, _value)
+                break
+        else:
+            self._list.append((_key, _value))
+            return
+        self._list[idx + 1 :] = [t for t in listiter if t[0].lower() != ikey]
+
+    def setdefault(self, key, default):
+        """Returns the value for the key if it is in the dict, otherwise it
+        returns `default` and sets that value for `key`.
+
+        :param key: The key to be looked up.
+        :param default: The default value to be returned if the key is not
+                        in the dict.  If not further specified it's `None`.
+        """
+        if key in self:
+            return self[key]
+        self.set(key, default)
+        return default
+
+    def __setitem__(self, key, value):
+        """Like :meth:`set` but also supports index/slice based setting."""
+        if isinstance(key, (slice, integer_types)):
+            if isinstance(key, integer_types):
+                value = [value]
+            value = [
+                (_unicodify_header_value(k), _unicodify_header_value(v))
+                for (k, v) in value
+            ]
+            [self._validate_value(v) for (k, v) in value]
+            if isinstance(key, integer_types):
+                self._list[key] = value[0]
+            else:
+                self._list[key] = value
+        else:
+            self.set(key, value)
+
+    def to_list(self, charset="iso-8859-1"):
+        """Convert the headers into a list suitable for WSGI.
+
+        .. deprecated:: 0.9
+        """
+        from warnings import warn
+
+        warn(
+            "'to_list' deprecated as of version 0.9 and will be removed"
+            " in version 1.0. Use 'to_wsgi_list' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.to_wsgi_list()
+
+    def to_wsgi_list(self):
+        """Convert the headers into a list suitable for WSGI.
+
+        The values are byte strings in Python 2 converted to latin1 and unicode
+        strings in Python 3 for the WSGI server to encode.
+
+        :return: list
+        """
+        if PY2:
+            return [(to_native(k), v.encode("latin1")) for k, v in self]
+        return list(self)
+
+    def copy(self):
+        return self.__class__(self._list)
+
+    def __copy__(self):
+        return self.copy()
+
+    def __str__(self):
+        """Returns formatted headers suitable for HTTP transmission."""
+        strs = []
+        for key, value in self.to_wsgi_list():
+            strs.append("%s: %s" % (key, value))
+        strs.append("\r\n")
+        return "\r\n".join(strs)
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, list(self))
+
+
+class ImmutableHeadersMixin(object):
+    """Makes a :class:`Headers` immutable.  We do not mark them as
+    hashable though since the only usecase for this datastructure
+    in Werkzeug is a view on a mutable structure.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    def __delitem__(self, key, **kwargs):
+        is_immutable(self)
+
+    def __setitem__(self, key, value):
+        is_immutable(self)
+
+    set = __setitem__
+
+    def add(self, item):
+        is_immutable(self)
+
+    remove = add_header = add
+
+    def extend(self, iterable):
+        is_immutable(self)
+
+    def insert(self, pos, value):
+        is_immutable(self)
+
+    def pop(self, index=-1):
+        is_immutable(self)
+
+    def popitem(self):
+        is_immutable(self)
+
+    def setdefault(self, key, default):
+        is_immutable(self)
+
+
+class EnvironHeaders(ImmutableHeadersMixin, Headers):
+    """Read only version of the headers from a WSGI environment.  This
+    provides the same interface as `Headers` and is constructed from
+    a WSGI environment.
+
+    From Werkzeug 0.3 onwards, the `KeyError` raised by this class is also a
+    subclass of the :exc:`~exceptions.BadRequest` HTTP exception and will
+    render a page for a ``400 BAD REQUEST`` if caught in a catch-all for
+    HTTP exceptions.
+    """
+
+    def __init__(self, environ):
+        self.environ = environ
+
+    def __eq__(self, other):
+        return self.environ is other.environ
+
+    __hash__ = None
+
+    def __getitem__(self, key, _get_mode=False):
+        # _get_mode is a no-op for this class as there is no index but
+        # used because get() calls it.
+        if not isinstance(key, string_types):
+            raise KeyError(key)
+        key = key.upper().replace("-", "_")
+        if key in ("CONTENT_TYPE", "CONTENT_LENGTH"):
+            return _unicodify_header_value(self.environ[key])
+        return _unicodify_header_value(self.environ["HTTP_" + key])
+
+    def __len__(self):
+        # the iter is necessary because otherwise list calls our
+        # len which would call list again and so forth.
+        return len(list(iter(self)))
+
+    def __iter__(self):
+        for key, value in iteritems(self.environ):
+            if key.startswith("HTTP_") and key not in (
+                "HTTP_CONTENT_TYPE",
+                "HTTP_CONTENT_LENGTH",
+            ):
+                yield (
+                    key[5:].replace("_", "-").title(),
+                    _unicodify_header_value(value),
+                )
+            elif key in ("CONTENT_TYPE", "CONTENT_LENGTH") and value:
+                yield (key.replace("_", "-").title(), _unicodify_header_value(value))
+
+    def copy(self):
+        raise TypeError("cannot create %r copies" % self.__class__.__name__)
+
+
+@native_itermethods(["keys", "values", "items", "lists", "listvalues"])
+class CombinedMultiDict(ImmutableMultiDictMixin, MultiDict):
+    """A read only :class:`MultiDict` that you can pass multiple :class:`MultiDict`
+    instances as sequence and it will combine the return values of all wrapped
+    dicts:
+
+    >>> from werkzeug.datastructures import CombinedMultiDict, MultiDict
+    >>> post = MultiDict([('foo', 'bar')])
+    >>> get = MultiDict([('blub', 'blah')])
+    >>> combined = CombinedMultiDict([get, post])
+    >>> combined['foo']
+    'bar'
+    >>> combined['blub']
+    'blah'
+
+    This works for all read operations and will raise a `TypeError` for
+    methods that usually change data which isn't possible.
+
+    From Werkzeug 0.3 onwards, the `KeyError` raised by this class is also a
+    subclass of the :exc:`~exceptions.BadRequest` HTTP exception and will
+    render a page for a ``400 BAD REQUEST`` if caught in a catch-all for HTTP
+    exceptions.
+    """
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (self.dicts,)
+
+    def __init__(self, dicts=None):
+        self.dicts = dicts or []
+
+    @classmethod
+    def fromkeys(cls):
+        raise TypeError("cannot create %r instances by fromkeys" % cls.__name__)
+
+    def __getitem__(self, key):
+        for d in self.dicts:
+            if key in d:
+                return d[key]
+        raise exceptions.BadRequestKeyError(key)
+
+    def get(self, key, default=None, type=None):
+        for d in self.dicts:
+            if key in d:
+                if type is not None:
+                    try:
+                        return type(d[key])
+                    except ValueError:
+                        continue
+                return d[key]
+        return default
+
+    def getlist(self, key, type=None):
+        rv = []
+        for d in self.dicts:
+            rv.extend(d.getlist(key, type))
+        return rv
+
+    def _keys_impl(self):
+        """This function exists so __len__ can be implemented more efficiently,
+        saving one list creation from an iterator.
+
+        Using this for Python 2's ``dict.keys`` behavior would be useless since
+        `dict.keys` in Python 2 returns a list, while we have a set here.
+        """
+        rv = set()
+        for d in self.dicts:
+            rv.update(iterkeys(d))
+        return rv
+
+    def keys(self):
+        return iter(self._keys_impl())
+
+    __iter__ = keys
+
+    def items(self, multi=False):
+        found = set()
+        for d in self.dicts:
+            for key, value in iteritems(d, multi):
+                if multi:
+                    yield key, value
+                elif key not in found:
+                    found.add(key)
+                    yield key, value
+
+    def values(self):
+        for _key, value in iteritems(self):
+            yield value
+
+    def lists(self):
+        rv = {}
+        for d in self.dicts:
+            for key, values in iterlists(d):
+                rv.setdefault(key, []).extend(values)
+        return iteritems(rv)
+
+    def listvalues(self):
+        return (x[1] for x in self.lists())
+
+    def copy(self):
+        """Return a shallow mutable copy of this object.
+
+        This returns a :class:`MultiDict` representing the data at the
+        time of copying. The copy will no longer reflect changes to the
+        wrapped dicts.
+
+        .. versionchanged:: 0.15
+            Return a mutable :class:`MultiDict`.
+        """
+        return MultiDict(self)
+
+    def to_dict(self, flat=True):
+        """Return the contents as regular dict.  If `flat` is `True` the
+        returned dict will only have the first item present, if `flat` is
+        `False` all values will be returned as lists.
+
+        :param flat: If set to `False` the dict returned will have lists
+                     with all the values in it.  Otherwise it will only
+                     contain the first item for each key.
+        :return: a :class:`dict`
+        """
+        rv = {}
+        for d in reversed(self.dicts):
+            rv.update(d.to_dict(flat))
+        return rv
+
+    def __len__(self):
+        return len(self._keys_impl())
+
+    def __contains__(self, key):
+        for d in self.dicts:
+            if key in d:
+                return True
+        return False
+
+    has_key = __contains__
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, self.dicts)
+
+
+class FileMultiDict(MultiDict):
+    """A special :class:`MultiDict` that has convenience methods to add
+    files to it.  This is used for :class:`EnvironBuilder` and generally
+    useful for unittesting.
+
+    .. versionadded:: 0.5
+    """
+
+    def add_file(self, name, file, filename=None, content_type=None):
+        """Adds a new file to the dict.  `file` can be a file name or
+        a :class:`file`-like or a :class:`FileStorage` object.
+
+        :param name: the name of the field.
+        :param file: a filename or :class:`file`-like object
+        :param filename: an optional filename
+        :param content_type: an optional content type
+        """
+        if isinstance(file, FileStorage):
+            value = file
+        else:
+            if isinstance(file, string_types):
+                if filename is None:
+                    filename = file
+                file = open(file, "rb")
+            if filename and content_type is None:
+                content_type = (
+                    mimetypes.guess_type(filename)[0] or "application/octet-stream"
+                )
+            value = FileStorage(file, filename, name, content_type)
+
+        self.add(name, value)
+
+
+class ImmutableDict(ImmutableDictMixin, dict):
+    """An immutable :class:`dict`.
+
+    .. versionadded:: 0.5
+    """
+
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, dict.__repr__(self))
+
+    def copy(self):
+        """Return a shallow mutable copy of this object.  Keep in mind that
+        the standard library's :func:`copy` function is a no-op for this class
+        like for any other python immutable type (eg: :class:`tuple`).
+        """
+        return dict(self)
+
+    def __copy__(self):
+        return self
+
+
+class ImmutableMultiDict(ImmutableMultiDictMixin, MultiDict):
+    """An immutable :class:`MultiDict`.
+
+    .. versionadded:: 0.5
+    """
+
+    def copy(self):
+        """Return a shallow mutable copy of this object.  Keep in mind that
+        the standard library's :func:`copy` function is a no-op for this class
+        like for any other python immutable type (eg: :class:`tuple`).
+        """
+        return MultiDict(self)
+
+    def __copy__(self):
+        return self
+
+
+class ImmutableOrderedMultiDict(ImmutableMultiDictMixin, OrderedMultiDict):
+    """An immutable :class:`OrderedMultiDict`.
+
+    .. versionadded:: 0.6
+    """
+
+    def _iter_hashitems(self):
+        return enumerate(iteritems(self, multi=True))
+
+    def copy(self):
+        """Return a shallow mutable copy of this object.  Keep in mind that
+        the standard library's :func:`copy` function is a no-op for this class
+        like for any other python immutable type (eg: :class:`tuple`).
+        """
+        return OrderedMultiDict(self)
+
+    def __copy__(self):
+        return self
+
+
+@native_itermethods(["values"])
+class Accept(ImmutableList):
+    """An :class:`Accept` object is just a list subclass for lists of
+    ``(value, quality)`` tuples.  It is automatically sorted by specificity
+    and quality.
+
+    All :class:`Accept` objects work similar to a list but provide extra
+    functionality for working with the data.  Containment checks are
+    normalized to the rules of that header:
+
+    >>> a = CharsetAccept([('ISO-8859-1', 1), ('utf-8', 0.7)])
+    >>> a.best
+    'ISO-8859-1'
+    >>> 'iso-8859-1' in a
+    True
+    >>> 'UTF8' in a
+    True
+    >>> 'utf7' in a
+    False
+
+    To get the quality for an item you can use normal item lookup:
+
+    >>> print a['utf-8']
+    0.7
+    >>> a['utf7']
+    0
+
+    .. versionchanged:: 0.5
+       :class:`Accept` objects are forced immutable now.
+    """
+
+    def __init__(self, values=()):
+        if values is None:
+            list.__init__(self)
+            self.provided = False
+        elif isinstance(values, Accept):
+            self.provided = values.provided
+            list.__init__(self, values)
+        else:
+            self.provided = True
+            values = sorted(
+                values,
+                key=lambda x: (self._specificity(x[0]), x[1], x[0]),
+                reverse=True,
+            )
+            list.__init__(self, values)
+
+    def _specificity(self, value):
+        """Returns a tuple describing the value's specificity."""
+        return (value != "*",)
+
+    def _value_matches(self, value, item):
+        """Check if a value matches a given accept item."""
+        return item == "*" or item.lower() == value.lower()
+
+    def __getitem__(self, key):
+        """Besides index lookup (getting item n) you can also pass it a string
+        to get the quality for the item.  If the item is not in the list, the
+        returned quality is ``0``.
+        """
+        if isinstance(key, string_types):
+            return self.quality(key)
+        return list.__getitem__(self, key)
+
+    def quality(self, key):
+        """Returns the quality of the key.
+
+        .. versionadded:: 0.6
+           In previous versions you had to use the item-lookup syntax
+           (eg: ``obj[key]`` instead of ``obj.quality(key)``)
+        """
+        for item, quality in self:
+            if self._value_matches(key, item):
+                return quality
+        return 0
+
+    def __contains__(self, value):
+        for item, _quality in self:
+            if self._value_matches(value, item):
+                return True
+        return False
+
+    def __repr__(self):
+        return "%s([%s])" % (
+            self.__class__.__name__,
+            ", ".join("(%r, %s)" % (x, y) for x, y in self),
+        )
+
+    def index(self, key):
+        """Get the position of an entry or raise :exc:`ValueError`.
+
+        :param key: The key to be looked up.
+
+        .. versionchanged:: 0.5
+           This used to raise :exc:`IndexError`, which was inconsistent
+           with the list API.
+        """
+        if isinstance(key, string_types):
+            for idx, (item, _quality) in enumerate(self):
+                if self._value_matches(key, item):
+                    return idx
+            raise ValueError(key)
+        return list.index(self, key)
+
+    def find(self, key):
+        """Get the position of an entry or return -1.
+
+        :param key: The key to be looked up.
+        """
+        try:
+            return self.index(key)
+        except ValueError:
+            return -1
+
+    def values(self):
+        """Iterate over all values."""
+        for item in self:
+            yield item[0]
+
+    def to_header(self):
+        """Convert the header set into an HTTP header string."""
+        result = []
+        for value, quality in self:
+            if quality != 1:
+                value = "%s;q=%s" % (value, quality)
+            result.append(value)
+        return ",".join(result)
+
+    def __str__(self):
+        return self.to_header()
+
+    def _best_single_match(self, match):
+        for client_item, quality in self:
+            if self._value_matches(match, client_item):
+                # self is sorted by specificity descending, we can exit
+                return client_item, quality
+
+    def best_match(self, matches, default=None):
+        """Returns the best match from a list of possible matches based
+        on the specificity and quality of the client. If two items have the
+        same quality and specificity, the one is returned that comes first.
+
+        :param matches: a list of matches to check for
+        :param default: the value that is returned if none match
+        """
+        result = default
+        best_quality = -1
+        best_specificity = (-1,)
+        for server_item in matches:
+            match = self._best_single_match(server_item)
+            if not match:
+                continue
+            client_item, quality = match
+            specificity = self._specificity(client_item)
+            if quality <= 0 or quality < best_quality:
+                continue
+            # better quality or same quality but more specific => better match
+            if quality > best_quality or specificity > best_specificity:
+                result = server_item
+                best_quality = quality
+                best_specificity = specificity
+        return result
+
+    @property
+    def best(self):
+        """The best match as value."""
+        if self:
+            return self[0][0]
+
+
+class MIMEAccept(Accept):
+    """Like :class:`Accept` but with special methods and behavior for
+    mimetypes.
+    """
+
+    def _specificity(self, value):
+        return tuple(x != "*" for x in value.split("/", 1))
+
+    def _value_matches(self, value, item):
+        def _normalize(x):
+            x = x.lower()
+            return ("*", "*") if x == "*" else x.split("/", 1)
+
+        # this is from the application which is trusted.  to avoid developer
+        # frustration we actually check these for valid values
+        if "/" not in value:
+            raise ValueError("invalid mimetype %r" % value)
+        value_type, value_subtype = _normalize(value)
+        if value_type == "*" and value_subtype != "*":
+            raise ValueError("invalid mimetype %r" % value)
+
+        if "/" not in item:
+            return False
+        item_type, item_subtype = _normalize(item)
+        if item_type == "*" and item_subtype != "*":
+            return False
+        return (
+            item_type == item_subtype == "*" or value_type == value_subtype == "*"
+        ) or (
+            item_type == value_type
+            and (
+                item_subtype == "*"
+                or value_subtype == "*"
+                or item_subtype == value_subtype
+            )
+        )
+
+    @property
+    def accept_html(self):
+        """True if this object accepts HTML."""
+        return (
+            "text/html" in self or "application/xhtml+xml" in self or self.accept_xhtml
+        )
+
+    @property
+    def accept_xhtml(self):
+        """True if this object accepts XHTML."""
+        return "application/xhtml+xml" in self or "application/xml" in self
+
+    @property
+    def accept_json(self):
+        """True if this object accepts JSON."""
+        return "application/json" in self
+
+
+class LanguageAccept(Accept):
+    """Like :class:`Accept` but with normalization for languages."""
+
+    def _value_matches(self, value, item):
+        def _normalize(language):
+            return _locale_delim_re.split(language.lower())
+
+        return item == "*" or _normalize(value) == _normalize(item)
+
+
+class CharsetAccept(Accept):
+    """Like :class:`Accept` but with normalization for charsets."""
+
+    def _value_matches(self, value, item):
+        def _normalize(name):
+            try:
+                return codecs.lookup(name).name
+            except LookupError:
+                return name.lower()
+
+        return item == "*" or _normalize(value) == _normalize(item)
+
+
+def cache_property(key, empty, type):
+    """Return a new property object for a cache header.  Useful if you
+    want to add support for a cache extension in a subclass."""
+    return property(
+        lambda x: x._get_cache_value(key, empty, type),
+        lambda x, v: x._set_cache_value(key, v, type),
+        lambda x: x._del_cache_value(key),
+        "accessor for %r" % key,
+    )
+
+
+class _CacheControl(UpdateDictMixin, dict):
+    """Subclass of a dict that stores values for a Cache-Control header.  It
+    has accessors for all the cache-control directives specified in RFC 2616.
+    The class does not differentiate between request and response directives.
+
+    Because the cache-control directives in the HTTP header use dashes the
+    python descriptors use underscores for that.
+
+    To get a header of the :class:`CacheControl` object again you can convert
+    the object into a string or call the :meth:`to_header` method.  If you plan
+    to subclass it and add your own items have a look at the sourcecode for
+    that class.
+
+    .. versionchanged:: 0.4
+
+       Setting `no_cache` or `private` to boolean `True` will set the implicit
+       none-value which is ``*``:
+
+       >>> cc = ResponseCacheControl()
+       >>> cc.no_cache = True
+       >>> cc
+       <ResponseCacheControl 'no-cache'>
+       >>> cc.no_cache
+       '*'
+       >>> cc.no_cache = None
+       >>> cc
+       <ResponseCacheControl ''>
+
+       In versions before 0.5 the behavior documented here affected the now
+       no longer existing `CacheControl` class.
+    """
+
+    no_cache = cache_property("no-cache", "*", None)
+    no_store = cache_property("no-store", None, bool)
+    max_age = cache_property("max-age", -1, int)
+    no_transform = cache_property("no-transform", None, None)
+
+    def __init__(self, values=(), on_update=None):
+        dict.__init__(self, values or ())
+        self.on_update = on_update
+        self.provided = values is not None
+
+    def _get_cache_value(self, key, empty, type):
+        """Used internally by the accessor properties."""
+        if type is bool:
+            return key in self
+        if key in self:
+            value = self[key]
+            if value is None:
+                return empty
+            elif type is not None:
+                try:
+                    value = type(value)
+                except ValueError:
+                    pass
+            return value
+
+    def _set_cache_value(self, key, value, type):
+        """Used internally by the accessor properties."""
+        if type is bool:
+            if value:
+                self[key] = None
+            else:
+                self.pop(key, None)
+        else:
+            if value is None:
+                self.pop(key)
+            elif value is True:
+                self[key] = None
+            else:
+                self[key] = value
+
+    def _del_cache_value(self, key):
+        """Used internally by the accessor properties."""
+        if key in self:
+            del self[key]
+
+    def to_header(self):
+        """Convert the stored values into a cache control header."""
+        return dump_header(self)
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "<%s %s>" % (
+            self.__class__.__name__,
+            " ".join("%s=%r" % (k, v) for k, v in sorted(self.items())),
+        )
+
+
+class RequestCacheControl(ImmutableDictMixin, _CacheControl):
+    """A cache control for requests.  This is immutable and gives access
+    to all the request-relevant cache control headers.
+
+    To get a header of the :class:`RequestCacheControl` object again you can
+    convert the object into a string or call the :meth:`to_header` method.  If
+    you plan to subclass it and add your own items have a look at the sourcecode
+    for that class.
+
+    .. versionadded:: 0.5
+       In previous versions a `CacheControl` class existed that was used
+       both for request and response.
+    """
+
+    max_stale = cache_property("max-stale", "*", int)
+    min_fresh = cache_property("min-fresh", "*", int)
+    no_transform = cache_property("no-transform", None, None)
+    only_if_cached = cache_property("only-if-cached", None, bool)
+
+
+class ResponseCacheControl(_CacheControl):
+    """A cache control for responses.  Unlike :class:`RequestCacheControl`
+    this is mutable and gives access to response-relevant cache control
+    headers.
+
+    To get a header of the :class:`ResponseCacheControl` object again you can
+    convert the object into a string or call the :meth:`to_header` method.  If
+    you plan to subclass it and add your own items have a look at the sourcecode
+    for that class.
+
+    .. versionadded:: 0.5
+       In previous versions a `CacheControl` class existed that was used
+       both for request and response.
+    """
+
+    public = cache_property("public", None, bool)
+    private = cache_property("private", "*", None)
+    must_revalidate = cache_property("must-revalidate", None, bool)
+    proxy_revalidate = cache_property("proxy-revalidate", None, bool)
+    s_maxage = cache_property("s-maxage", None, None)
+
+
+# attach cache_property to the _CacheControl as staticmethod
+# so that others can reuse it.
+_CacheControl.cache_property = staticmethod(cache_property)
+
+
+class CallbackDict(UpdateDictMixin, dict):
+    """A dict that calls a function passed every time something is changed.
+    The function is passed the dict instance.
+    """
+
+    def __init__(self, initial=None, on_update=None):
+        dict.__init__(self, initial or ())
+        self.on_update = on_update
+
+    def __repr__(self):
+        return "<%s %s>" % (self.__class__.__name__, dict.__repr__(self))
+
+
+class HeaderSet(collections_abc.MutableSet):
+    """Similar to the :class:`ETags` class this implements a set-like structure.
+    Unlike :class:`ETags` this is case insensitive and used for vary, allow, and
+    content-language headers.
+
+    If not constructed using the :func:`parse_set_header` function the
+    instantiation works like this:
+
+    >>> hs = HeaderSet(['foo', 'bar', 'baz'])
+    >>> hs
+    HeaderSet(['foo', 'bar', 'baz'])
+    """
+
+    def __init__(self, headers=None, on_update=None):
+        self._headers = list(headers or ())
+        self._set = set([x.lower() for x in self._headers])
+        self.on_update = on_update
+
+    def add(self, header):
+        """Add a new header to the set."""
+        self.update((header,))
+
+    def remove(self, header):
+        """Remove a header from the set.  This raises an :exc:`KeyError` if the
+        header is not in the set.
+
+        .. versionchanged:: 0.5
+            In older versions a :exc:`IndexError` was raised instead of a
+            :exc:`KeyError` if the object was missing.
+
+        :param header: the header to be removed.
+        """
+        key = header.lower()
+        if key not in self._set:
+            raise KeyError(header)
+        self._set.remove(key)
+        for idx, key in enumerate(self._headers):
+            if key.lower() == header:
+                del self._headers[idx]
+                break
+        if self.on_update is not None:
+            self.on_update(self)
+
+    def update(self, iterable):
+        """Add all the headers from the iterable to the set.
+
+        :param iterable: updates the set with the items from the iterable.
+        """
+        inserted_any = False
+        for header in iterable:
+            key = header.lower()
+            if key not in self._set:
+                self._headers.append(header)
+                self._set.add(key)
+                inserted_any = True
+        if inserted_any and self.on_update is not None:
+            self.on_update(self)
+
+    def discard(self, header):
+        """Like :meth:`remove` but ignores errors.
+
+        :param header: the header to be discarded.
+        """
+        try:
+            return self.remove(header)
+        except KeyError:
+            pass
+
+    def find(self, header):
+        """Return the index of the header in the set or return -1 if not found.
+
+        :param header: the header to be looked up.
+        """
+        header = header.lower()
+        for idx, item in enumerate(self._headers):
+            if item.lower() == header:
+                return idx
+        return -1
+
+    def index(self, header):
+        """Return the index of the header in the set or raise an
+        :exc:`IndexError`.
+
+        :param header: the header to be looked up.
+        """
+        rv = self.find(header)
+        if rv < 0:
+            raise IndexError(header)
+        return rv
+
+    def clear(self):
+        """Clear the set."""
+        self._set.clear()
+        del self._headers[:]
+        if self.on_update is not None:
+            self.on_update(self)
+
+    def as_set(self, preserve_casing=False):
+        """Return the set as real python set type.  When calling this, all
+        the items are converted to lowercase and the ordering is lost.
+
+        :param preserve_casing: if set to `True` the items in the set returned
+                                will have the original case like in the
+                                :class:`HeaderSet`, otherwise they will
+                                be lowercase.
+        """
+        if preserve_casing:
+            return set(self._headers)
+        return set(self._set)
+
+    def to_header(self):
+        """Convert the header set into an HTTP header string."""
+        return ", ".join(map(quote_header_value, self._headers))
+
+    def __getitem__(self, idx):
+        return self._headers[idx]
+
+    def __delitem__(self, idx):
+        rv = self._headers.pop(idx)
+        self._set.remove(rv.lower())
+        if self.on_update is not None:
+            self.on_update(self)
+
+    def __setitem__(self, idx, value):
+        old = self._headers[idx]
+        self._set.remove(old.lower())
+        self._headers[idx] = value
+        self._set.add(value.lower())
+        if self.on_update is not None:
+            self.on_update(self)
+
+    def __contains__(self, header):
+        return header.lower() in self._set
+
+    def __len__(self):
+        return len(self._set)
+
+    def __iter__(self):
+        return iter(self._headers)
+
+    def __nonzero__(self):
+        return bool(self._set)
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "%s(%r)" % (self.__class__.__name__, self._headers)
+
+
+class ETags(collections_abc.Container, collections_abc.Iterable):
+    """A set that can be used to check if one etag is present in a collection
+    of etags.
+    """
+
+    def __init__(self, strong_etags=None, weak_etags=None, star_tag=False):
+        self._strong = frozenset(not star_tag and strong_etags or ())
+        self._weak = frozenset(weak_etags or ())
+        self.star_tag = star_tag
+
+    def as_set(self, include_weak=False):
+        """Convert the `ETags` object into a python set.  Per default all the
+        weak etags are not part of this set."""
+        rv = set(self._strong)
+        if include_weak:
+            rv.update(self._weak)
+        return rv
+
+    def is_weak(self, etag):
+        """Check if an etag is weak."""
+        return etag in self._weak
+
+    def is_strong(self, etag):
+        """Check if an etag is strong."""
+        return etag in self._strong
+
+    def contains_weak(self, etag):
+        """Check if an etag is part of the set including weak and strong tags."""
+        return self.is_weak(etag) or self.contains(etag)
+
+    def contains(self, etag):
+        """Check if an etag is part of the set ignoring weak tags.
+        It is also possible to use the ``in`` operator.
+        """
+        if self.star_tag:
+            return True
+        return self.is_strong(etag)
+
+    def contains_raw(self, etag):
+        """When passed a quoted tag it will check if this tag is part of the
+        set.  If the tag is weak it is checked against weak and strong tags,
+        otherwise strong only."""
+        etag, weak = unquote_etag(etag)
+        if weak:
+            return self.contains_weak(etag)
+        return self.contains(etag)
+
+    def to_header(self):
+        """Convert the etags set into a HTTP header string."""
+        if self.star_tag:
+            return "*"
+        return ", ".join(
+            ['"%s"' % x for x in self._strong] + ['W/"%s"' % x for x in self._weak]
+        )
+
+    def __call__(self, etag=None, data=None, include_weak=False):
+        if [etag, data].count(None) != 1:
+            raise TypeError("either tag or data required, but at least one")
+        if etag is None:
+            etag = generate_etag(data)
+        if include_weak:
+            if etag in self._weak:
+                return True
+        return etag in self._strong
+
+    def __bool__(self):
+        return bool(self.star_tag or self._strong or self._weak)
+
+    __nonzero__ = __bool__
+
+    def __str__(self):
+        return self.to_header()
+
+    def __iter__(self):
+        return iter(self._strong)
+
+    def __contains__(self, etag):
+        return self.contains(etag)
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, str(self))
+
+
+class IfRange(object):
+    """Very simple object that represents the `If-Range` header in parsed
+    form.  It will either have neither a etag or date or one of either but
+    never both.
+
+    .. versionadded:: 0.7
+    """
+
+    def __init__(self, etag=None, date=None):
+        #: The etag parsed and unquoted.  Ranges always operate on strong
+        #: etags so the weakness information is not necessary.
+        self.etag = etag
+        #: The date in parsed format or `None`.
+        self.date = date
+
+    def to_header(self):
+        """Converts the object back into an HTTP header."""
+        if self.date is not None:
+            return http_date(self.date)
+        if self.etag is not None:
+            return quote_etag(self.etag)
+        return ""
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, str(self))
+
+
+class Range(object):
+    """Represents a ``Range`` header. All methods only support only
+    bytes as the unit. Stores a list of ranges if given, but the methods
+    only work if only one range is provided.
+
+    :raise ValueError: If the ranges provided are invalid.
+
+    .. versionchanged:: 0.15
+        The ranges passed in are validated.
+
+    .. versionadded:: 0.7
+    """
+
+    def __init__(self, units, ranges):
+        #: The units of this range.  Usually "bytes".
+        self.units = units
+        #: A list of ``(begin, end)`` tuples for the range header provided.
+        #: The ranges are non-inclusive.
+        self.ranges = ranges
+
+        for start, end in ranges:
+            if start is None or (end is not None and (start < 0 or start >= end)):
+                raise ValueError("{} is not a valid range.".format((start, end)))
+
+    def range_for_length(self, length):
+        """If the range is for bytes, the length is not None and there is
+        exactly one range and it is satisfiable it returns a ``(start, stop)``
+        tuple, otherwise `None`.
+        """
+        if self.units != "bytes" or length is None or len(self.ranges) != 1:
+            return None
+        start, end = self.ranges[0]
+        if end is None:
+            end = length
+            if start < 0:
+                start += length
+        if is_byte_range_valid(start, end, length):
+            return start, min(end, length)
+
+    def make_content_range(self, length):
+        """Creates a :class:`~werkzeug.datastructures.ContentRange` object
+        from the current range and given content length.
+        """
+        rng = self.range_for_length(length)
+        if rng is not None:
+            return ContentRange(self.units, rng[0], rng[1], length)
+
+    def to_header(self):
+        """Converts the object back into an HTTP header."""
+        ranges = []
+        for begin, end in self.ranges:
+            if end is None:
+                ranges.append("%s-" % begin if begin >= 0 else str(begin))
+            else:
+                ranges.append("%s-%s" % (begin, end - 1))
+        return "%s=%s" % (self.units, ",".join(ranges))
+
+    def to_content_range_header(self, length):
+        """Converts the object into `Content-Range` HTTP header,
+        based on given length
+        """
+        range_for_length = self.range_for_length(length)
+        if range_for_length is not None:
+            return "%s %d-%d/%d" % (
+                self.units,
+                range_for_length[0],
+                range_for_length[1] - 1,
+                length,
+            )
+        return None
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, str(self))
+
+
+class ContentRange(object):
+    """Represents the content range header.
+
+    .. versionadded:: 0.7
+    """
+
+    def __init__(self, units, start, stop, length=None, on_update=None):
+        assert is_byte_range_valid(start, stop, length), "Bad range provided"
+        self.on_update = on_update
+        self.set(start, stop, length, units)
+
+    def _callback_property(name):  # noqa: B902
+        def fget(self):
+            return getattr(self, name)
+
+        def fset(self, value):
+            setattr(self, name, value)
+            if self.on_update is not None:
+                self.on_update(self)
+
+        return property(fget, fset)
+
+    #: The units to use, usually "bytes"
+    units = _callback_property("_units")
+    #: The start point of the range or `None`.
+    start = _callback_property("_start")
+    #: The stop point of the range (non-inclusive) or `None`.  Can only be
+    #: `None` if also start is `None`.
+    stop = _callback_property("_stop")
+    #: The length of the range or `None`.
+    length = _callback_property("_length")
+    del _callback_property
+
+    def set(self, start, stop, length=None, units="bytes"):
+        """Simple method to update the ranges."""
+        assert is_byte_range_valid(start, stop, length), "Bad range provided"
+        self._units = units
+        self._start = start
+        self._stop = stop
+        self._length = length
+        if self.on_update is not None:
+            self.on_update(self)
+
+    def unset(self):
+        """Sets the units to `None` which indicates that the header should
+        no longer be used.
+        """
+        self.set(None, None, units=None)
+
+    def to_header(self):
+        if self.units is None:
+            return ""
+        if self.length is None:
+            length = "*"
+        else:
+            length = self.length
+        if self.start is None:
+            return "%s */%s" % (self.units, length)
+        return "%s %s-%s/%s" % (self.units, self.start, self.stop - 1, length)
+
+    def __nonzero__(self):
+        return self.units is not None
+
+    __bool__ = __nonzero__
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, str(self))
+
+
+class Authorization(ImmutableDictMixin, dict):
+    """Represents an `Authorization` header sent by the client.  You should
+    not create this kind of object yourself but use it when it's returned by
+    the `parse_authorization_header` function.
+
+    This object is a dict subclass and can be altered by setting dict items
+    but it should be considered immutable as it's returned by the client and
+    not meant for modifications.
+
+    .. versionchanged:: 0.5
+       This object became immutable.
+    """
+
+    def __init__(self, auth_type, data=None):
+        dict.__init__(self, data or {})
+        self.type = auth_type
+
+    username = property(
+        lambda self: self.get("username"),
+        doc="""
+        The username transmitted.  This is set for both basic and digest
+        auth all the time.""",
+    )
+    password = property(
+        lambda self: self.get("password"),
+        doc="""
+        When the authentication type is basic this is the password
+        transmitted by the client, else `None`.""",
+    )
+    realm = property(
+        lambda self: self.get("realm"),
+        doc="""
+        This is the server realm sent back for HTTP digest auth.""",
+    )
+    nonce = property(
+        lambda self: self.get("nonce"),
+        doc="""
+        The nonce the server sent for digest auth, sent back by the client.
+        A nonce should be unique for every 401 response for HTTP digest
+        auth.""",
+    )
+    uri = property(
+        lambda self: self.get("uri"),
+        doc="""
+        The URI from Request-URI of the Request-Line; duplicated because
+        proxies are allowed to change the Request-Line in transit.  HTTP
+        digest auth only.""",
+    )
+    nc = property(
+        lambda self: self.get("nc"),
+        doc="""
+        The nonce count value transmitted by clients if a qop-header is
+        also transmitted.  HTTP digest auth only.""",
+    )
+    cnonce = property(
+        lambda self: self.get("cnonce"),
+        doc="""
+        If the server sent a qop-header in the ``WWW-Authenticate``
+        header, the client has to provide this value for HTTP digest auth.
+        See the RFC for more details.""",
+    )
+    response = property(
+        lambda self: self.get("response"),
+        doc="""
+        A string of 32 hex digits computed as defined in RFC 2617, which
+        proves that the user knows a password.  Digest auth only.""",
+    )
+    opaque = property(
+        lambda self: self.get("opaque"),
+        doc="""
+        The opaque header from the server returned unchanged by the client.
+        It is recommended that this string be base64 or hexadecimal data.
+        Digest auth only.""",
+    )
+    qop = property(
+        lambda self: self.get("qop"),
+        doc="""
+        Indicates what "quality of protection" the client has applied to
+        the message for HTTP digest auth. Note that this is a single token,
+        not a quoted list of alternatives as in WWW-Authenticate.""",
+    )
+
+
+class WWWAuthenticate(UpdateDictMixin, dict):
+    """Provides simple access to `WWW-Authenticate` headers."""
+
+    #: list of keys that require quoting in the generated header
+    _require_quoting = frozenset(["domain", "nonce", "opaque", "realm", "qop"])
+
+    def __init__(self, auth_type=None, values=None, on_update=None):
+        dict.__init__(self, values or ())
+        if auth_type:
+            self["__auth_type__"] = auth_type
+        self.on_update = on_update
+
+    def set_basic(self, realm="authentication required"):
+        """Clear the auth info and enable basic auth."""
+        dict.clear(self)
+        dict.update(self, {"__auth_type__": "basic", "realm": realm})
+        if self.on_update:
+            self.on_update(self)
+
+    def set_digest(
+        self, realm, nonce, qop=("auth",), opaque=None, algorithm=None, stale=False
+    ):
+        """Clear the auth info and enable digest auth."""
+        d = {
+            "__auth_type__": "digest",
+            "realm": realm,
+            "nonce": nonce,
+            "qop": dump_header(qop),
+        }
+        if stale:
+            d["stale"] = "TRUE"
+        if opaque is not None:
+            d["opaque"] = opaque
+        if algorithm is not None:
+            d["algorithm"] = algorithm
+        dict.clear(self)
+        dict.update(self, d)
+        if self.on_update:
+            self.on_update(self)
+
+    def to_header(self):
+        """Convert the stored values into a WWW-Authenticate header."""
+        d = dict(self)
+        auth_type = d.pop("__auth_type__", None) or "basic"
+        return "%s %s" % (
+            auth_type.title(),
+            ", ".join(
+                [
+                    "%s=%s"
+                    % (
+                        key,
+                        quote_header_value(
+                            value, allow_token=key not in self._require_quoting
+                        ),
+                    )
+                    for key, value in iteritems(d)
+                ]
+            ),
+        )
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, self.to_header())
+
+    def auth_property(name, doc=None):  # noqa: B902
+        """A static helper function for subclasses to add extra authentication
+        system properties onto a class::
+
+            class FooAuthenticate(WWWAuthenticate):
+                special_realm = auth_property('special_realm')
+
+        For more information have a look at the sourcecode to see how the
+        regular properties (:attr:`realm` etc.) are implemented.
+        """
+
+        def _set_value(self, value):
+            if value is None:
+                self.pop(name, None)
+            else:
+                self[name] = str(value)
+
+        return property(lambda x: x.get(name), _set_value, doc=doc)
+
+    def _set_property(name, doc=None):  # noqa: B902
+        def fget(self):
+            def on_update(header_set):
+                if not header_set and name in self:
+                    del self[name]
+                elif header_set:
+                    self[name] = header_set.to_header()
+
+            return parse_set_header(self.get(name), on_update)
+
+        return property(fget, doc=doc)
+
+    type = auth_property(
+        "__auth_type__",
+        doc="""The type of the auth mechanism. HTTP currently specifies
+        ``Basic`` and ``Digest``.""",
+    )
+    realm = auth_property(
+        "realm",
+        doc="""A string to be displayed to users so they know which
+        username and password to use. This string should contain at
+        least the name of the host performing the authentication and
+        might additionally indicate the collection of users who might
+        have access.""",
+    )
+    domain = _set_property(
+        "domain",
+        doc="""A list of URIs that define the protection space. If a URI
+        is an absolute path, it is relative to the canonical root URL of
+        the server being accessed.""",
+    )
+    nonce = auth_property(
+        "nonce",
+        doc="""
+        A server-specified data string which should be uniquely generated
+        each time a 401 response is made. It is recommended that this
+        string be base64 or hexadecimal data.""",
+    )
+    opaque = auth_property(
+        "opaque",
+        doc="""A string of data, specified by the server, which should
+        be returned by the client unchanged in the Authorization header
+        of subsequent requests with URIs in the same protection space.
+        It is recommended that this string be base64 or hexadecimal
+        data.""",
+    )
+    algorithm = auth_property(
+        "algorithm",
+        doc="""A string indicating a pair of algorithms used to produce
+        the digest and a checksum. If this is not present it is assumed
+        to be "MD5". If the algorithm is not understood, the challenge
+        should be ignored (and a different one used, if there is more
+        than one).""",
+    )
+    qop = _set_property(
+        "qop",
+        doc="""A set of quality-of-privacy directives such as auth and
+        auth-int.""",
+    )
+
+    @property
+    def stale(self):
+        """A flag, indicating that the previous request from the client
+        was rejected because the nonce value was stale.
+        """
+        val = self.get("stale")
+        if val is not None:
+            return val.lower() == "true"
+
+    @stale.setter
+    def stale(self, value):
+        if value is None:
+            self.pop("stale", None)
+        else:
+            self["stale"] = "TRUE" if value else "FALSE"
+
+    auth_property = staticmethod(auth_property)
+    del _set_property
+
+
+class FileStorage(object):
+    """The :class:`FileStorage` class is a thin wrapper over incoming files.
+    It is used by the request object to represent uploaded files.  All the
+    attributes of the wrapper stream are proxied by the file storage so
+    it's possible to do ``storage.read()`` instead of the long form
+    ``storage.stream.read()``.
+    """
+
+    def __init__(
+        self,
+        stream=None,
+        filename=None,
+        name=None,
+        content_type=None,
+        content_length=None,
+        headers=None,
+    ):
+        self.name = name
+        self.stream = stream or BytesIO()
+
+        # if no filename is provided we can attempt to get the filename
+        # from the stream object passed.  There we have to be careful to
+        # skip things like <fdopen>, <stderr> etc.  Python marks these
+        # special filenames with angular brackets.
+        if filename is None:
+            filename = getattr(stream, "name", None)
+            s = make_literal_wrapper(filename)
+            if filename and filename[0] == s("<") and filename[-1] == s(">"):
+                filename = None
+
+            # On Python 3 we want to make sure the filename is always unicode.
+            # This might not be if the name attribute is bytes due to the
+            # file being opened from the bytes API.
+            if not PY2 and isinstance(filename, bytes):
+                filename = filename.decode(get_filesystem_encoding(), "replace")
+
+        self.filename = filename
+        if headers is None:
+            headers = Headers()
+        self.headers = headers
+        if content_type is not None:
+            headers["Content-Type"] = content_type
+        if content_length is not None:
+            headers["Content-Length"] = str(content_length)
+
+    def _parse_content_type(self):
+        if not hasattr(self, "_parsed_content_type"):
+            self._parsed_content_type = parse_options_header(self.content_type)
+
+    @property
+    def content_type(self):
+        """The content-type sent in the header.  Usually not available"""
+        return self.headers.get("content-type")
+
+    @property
+    def content_length(self):
+        """The content-length sent in the header.  Usually not available"""
+        return int(self.headers.get("content-length") or 0)
+
+    @property
+    def mimetype(self):
+        """Like :attr:`content_type`, but without parameters (eg, without
+        charset, type etc.) and always lowercase.  For example if the content
+        type is ``text/HTML; charset=utf-8`` the mimetype would be
+        ``'text/html'``.
+
+        .. versionadded:: 0.7
+        """
+        self._parse_content_type()
+        return self._parsed_content_type[0].lower()
+
+    @property
+    def mimetype_params(self):
+        """The mimetype parameters as dict.  For example if the content
+        type is ``text/html; charset=utf-8`` the params would be
+        ``{'charset': 'utf-8'}``.
+
+        .. versionadded:: 0.7
+        """
+        self._parse_content_type()
+        return self._parsed_content_type[1]
+
+    def save(self, dst, buffer_size=16384):
+        """Save the file to a destination path or file object.  If the
+        destination is a file object you have to close it yourself after the
+        call.  The buffer size is the number of bytes held in memory during
+        the copy process.  It defaults to 16KB.
+
+        For secure file saving also have a look at :func:`secure_filename`.
+
+        :param dst: a filename or open file object the uploaded file
+                    is saved to.
+        :param buffer_size: the size of the buffer.  This works the same as
+                            the `length` parameter of
+                            :func:`shutil.copyfileobj`.
+        """
+        from shutil import copyfileobj
+
+        close_dst = False
+        if isinstance(dst, string_types):
+            dst = open(dst, "wb")
+            close_dst = True
+        try:
+            copyfileobj(self.stream, dst, buffer_size)
+        finally:
+            if close_dst:
+                dst.close()
+
+    def close(self):
+        """Close the underlying file if possible."""
+        try:
+            self.stream.close()
+        except Exception:
+            pass
+
+    def __nonzero__(self):
+        return bool(self.filename)
+
+    __bool__ = __nonzero__
+
+    def __getattr__(self, name):
+        try:
+            return getattr(self.stream, name)
+        except AttributeError:
+            # SpooledTemporaryFile doesn't implement IOBase, get the
+            # attribute from its backing file instead.
+            # https://github.com/python/cpython/pull/3249
+            if hasattr(self.stream, "_file"):
+                return getattr(self.stream._file, name)
+            raise
+
+    def __iter__(self):
+        return iter(self.stream)
+
+    def __repr__(self):
+        return "<%s: %r (%r)>" % (
+            self.__class__.__name__,
+            self.filename,
+            self.content_type,
+        )
+
+
+# circular dependencies
+from . import exceptions
+from .http import dump_header
+from .http import dump_options_header
+from .http import generate_etag
+from .http import http_date
+from .http import is_byte_range_valid
+from .http import parse_options_header
+from .http import parse_set_header
+from .http import quote_etag
+from .http import quote_header_value
+from .http import unquote_etag
diff --git a/python/werkzeug/exceptions.py b/python/werkzeug/exceptions.py
new file mode 100644
index 0000000..fb6528d
--- /dev/null
+++ b/python/werkzeug/exceptions.py
@@ -0,0 +1,774 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.exceptions
+    ~~~~~~~~~~~~~~~~~~~
+
+    This module implements a number of Python exceptions you can raise from
+    within your views to trigger a standard non-200 response.
+
+
+    Usage Example
+    -------------
+
+    ::
+
+        from werkzeug.wrappers import BaseRequest
+        from werkzeug.wsgi import responder
+        from werkzeug.exceptions import HTTPException, NotFound
+
+        def view(request):
+            raise NotFound()
+
+        @responder
+        def application(environ, start_response):
+            request = BaseRequest(environ)
+            try:
+                return view(request)
+            except HTTPException as e:
+                return e
+
+
+    As you can see from this example those exceptions are callable WSGI
+    applications.  Because of Python 2.4 compatibility those do not extend
+    from the response objects but only from the python exception class.
+
+    As a matter of fact they are not Werkzeug response objects.  However you
+    can get a response object by calling ``get_response()`` on a HTTP
+    exception.
+
+    Keep in mind that you have to pass an environment to ``get_response()``
+    because some errors fetch additional information from the WSGI
+    environment.
+
+    If you want to hook in a different exception page to say, a 404 status
+    code, you can add a second except for a specific subclass of an error::
+
+        @responder
+        def application(environ, start_response):
+            request = BaseRequest(environ)
+            try:
+                return view(request)
+            except NotFound, e:
+                return not_found(request)
+            except HTTPException, e:
+                return e
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import sys
+
+import werkzeug
+
+# Because of bootstrapping reasons we need to manually patch ourselves
+# onto our parent module.
+werkzeug.exceptions = sys.modules[__name__]
+
+from ._compat import implements_to_string
+from ._compat import integer_types
+from ._compat import iteritems
+from ._compat import text_type
+from ._internal import _get_environ
+from .wrappers import Response
+
+
+@implements_to_string
+class HTTPException(Exception):
+    """Baseclass for all HTTP exceptions.  This exception can be called as WSGI
+    application to render a default error page or you can catch the subclasses
+    of it independently and render nicer error messages.
+    """
+
+    code = None
+    description = None
+
+    def __init__(self, description=None, response=None):
+        super(Exception, self).__init__()
+        if description is not None:
+            self.description = description
+        self.response = response
+
+    @classmethod
+    def wrap(cls, exception, name=None):
+        """Create an exception that is a subclass of the calling HTTP
+        exception and the ``exception`` argument.
+
+        The first argument to the class will be passed to the
+        wrapped ``exception``, the rest to the HTTP exception. If
+        ``self.args`` is not empty, the wrapped exception message is
+        added to the HTTP exception description.
+
+        .. versionchanged:: 0.15
+            The description includes the wrapped exception message.
+        """
+
+        class newcls(cls, exception):
+            def __init__(self, arg=None, *args, **kwargs):
+                super(cls, self).__init__(*args, **kwargs)
+
+                if arg is None:
+                    exception.__init__(self)
+                else:
+                    exception.__init__(self, arg)
+
+            def get_description(self, environ=None):
+                out = super(cls, self).get_description(environ=environ)
+
+                if self.args:
+                    out += "<p><pre><code>{}: {}</code></pre></p>".format(
+                        exception.__name__, escape(exception.__str__(self))
+                    )
+
+                return out
+
+        newcls.__module__ = sys._getframe(1).f_globals.get("__name__")
+        newcls.__name__ = name or cls.__name__ + exception.__name__
+        return newcls
+
+    @property
+    def name(self):
+        """The status name."""
+        return HTTP_STATUS_CODES.get(self.code, "Unknown Error")
+
+    def get_description(self, environ=None):
+        """Get the description."""
+        return u"<p>%s</p>" % escape(self.description)
+
+    def get_body(self, environ=None):
+        """Get the HTML body."""
+        return text_type(
+            (
+                u'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n'
+                u"<title>%(code)s %(name)s</title>\n"
+                u"<h1>%(name)s</h1>\n"
+                u"%(description)s\n"
+            )
+            % {
+                "code": self.code,
+                "name": escape(self.name),
+                "description": self.get_description(environ),
+            }
+        )
+
+    def get_headers(self, environ=None):
+        """Get a list of headers."""
+        return [("Content-Type", "text/html")]
+
+    def get_response(self, environ=None):
+        """Get a response object.  If one was passed to the exception
+        it's returned directly.
+
+        :param environ: the optional environ for the request.  This
+                        can be used to modify the response depending
+                        on how the request looked like.
+        :return: a :class:`Response` object or a subclass thereof.
+        """
+        if self.response is not None:
+            return self.response
+        if environ is not None:
+            environ = _get_environ(environ)
+        headers = self.get_headers(environ)
+        return Response(self.get_body(environ), self.code, headers)
+
+    def __call__(self, environ, start_response):
+        """Call the exception as WSGI application.
+
+        :param environ: the WSGI environment.
+        :param start_response: the response callable provided by the WSGI
+                               server.
+        """
+        response = self.get_response(environ)
+        return response(environ, start_response)
+
+    def __str__(self):
+        code = self.code if self.code is not None else "???"
+        return "%s %s: %s" % (code, self.name, self.description)
+
+    def __repr__(self):
+        code = self.code if self.code is not None else "???"
+        return "<%s '%s: %s'>" % (self.__class__.__name__, code, self.name)
+
+
+class BadRequest(HTTPException):
+    """*400* `Bad Request`
+
+    Raise if the browser sends something to the application the application
+    or server cannot handle.
+    """
+
+    code = 400
+    description = (
+        "The browser (or proxy) sent a request that this server could "
+        "not understand."
+    )
+
+
+class ClientDisconnected(BadRequest):
+    """Internal exception that is raised if Werkzeug detects a disconnected
+    client.  Since the client is already gone at that point attempting to
+    send the error message to the client might not work and might ultimately
+    result in another exception in the server.  Mainly this is here so that
+    it is silenced by default as far as Werkzeug is concerned.
+
+    Since disconnections cannot be reliably detected and are unspecified
+    by WSGI to a large extent this might or might not be raised if a client
+    is gone.
+
+    .. versionadded:: 0.8
+    """
+
+
+class SecurityError(BadRequest):
+    """Raised if something triggers a security error.  This is otherwise
+    exactly like a bad request error.
+
+    .. versionadded:: 0.9
+    """
+
+
+class BadHost(BadRequest):
+    """Raised if the submitted host is badly formatted.
+
+    .. versionadded:: 0.11.2
+    """
+
+
+class Unauthorized(HTTPException):
+    """*401* ``Unauthorized``
+
+    Raise if the user is not authorized to access a resource.
+
+    The ``www_authenticate`` argument should be used to set the
+    ``WWW-Authenticate`` header. This is used for HTTP basic auth and
+    other schemes. Use :class:`~werkzeug.datastructures.WWWAuthenticate`
+    to create correctly formatted values. Strictly speaking a 401
+    response is invalid if it doesn't provide at least one value for
+    this header, although real clients typically don't care.
+
+    :param description: Override the default message used for the body
+        of the response.
+    :param www-authenticate: A single value, or list of values, for the
+        WWW-Authenticate header.
+
+    .. versionchanged:: 0.15.3
+        If the ``www_authenticate`` argument is not set, the
+        ``WWW-Authenticate`` header is not set.
+
+    .. versionchanged:: 0.15.3
+        The ``response`` argument was restored.
+
+    .. versionchanged:: 0.15.1
+        ``description`` was moved back as the first argument, restoring
+         its previous position.
+
+    .. versionchanged:: 0.15.0
+        ``www_authenticate`` was added as the first argument, ahead of
+        ``description``.
+    """
+
+    code = 401
+    description = (
+        "The server could not verify that you are authorized to access"
+        " the URL requested. You either supplied the wrong credentials"
+        " (e.g. a bad password), or your browser doesn't understand"
+        " how to supply the credentials required."
+    )
+
+    def __init__(self, description=None, response=None, www_authenticate=None):
+        HTTPException.__init__(self, description, response)
+
+        if www_authenticate is not None:
+            if not isinstance(www_authenticate, (tuple, list)):
+                www_authenticate = (www_authenticate,)
+
+        self.www_authenticate = www_authenticate
+
+    def get_headers(self, environ=None):
+        headers = HTTPException.get_headers(self, environ)
+        if self.www_authenticate:
+            headers.append(
+                ("WWW-Authenticate", ", ".join([str(x) for x in self.www_authenticate]))
+            )
+        return headers
+
+
+class Forbidden(HTTPException):
+    """*403* `Forbidden`
+
+    Raise if the user doesn't have the permission for the requested resource
+    but was authenticated.
+    """
+
+    code = 403
+    description = (
+        "You don't have the permission to access the requested"
+        " resource. It is either read-protected or not readable by the"
+        " server."
+    )
+
+
+class NotFound(HTTPException):
+    """*404* `Not Found`
+
+    Raise if a resource does not exist and never existed.
+    """
+
+    code = 404
+    description = (
+        "The requested URL was not found on the server. If you entered"
+        " the URL manually please check your spelling and try again."
+    )
+
+
+class MethodNotAllowed(HTTPException):
+    """*405* `Method Not Allowed`
+
+    Raise if the server used a method the resource does not handle.  For
+    example `POST` if the resource is view only.  Especially useful for REST.
+
+    The first argument for this exception should be a list of allowed methods.
+    Strictly speaking the response would be invalid if you don't provide valid
+    methods in the header which you can do with that list.
+    """
+
+    code = 405
+    description = "The method is not allowed for the requested URL."
+
+    def __init__(self, valid_methods=None, description=None):
+        """Takes an optional list of valid http methods
+        starting with werkzeug 0.3 the list will be mandatory."""
+        HTTPException.__init__(self, description)
+        self.valid_methods = valid_methods
+
+    def get_headers(self, environ=None):
+        headers = HTTPException.get_headers(self, environ)
+        if self.valid_methods:
+            headers.append(("Allow", ", ".join(self.valid_methods)))
+        return headers
+
+
+class NotAcceptable(HTTPException):
+    """*406* `Not Acceptable`
+
+    Raise if the server can't return any content conforming to the
+    `Accept` headers of the client.
+    """
+
+    code = 406
+
+    description = (
+        "The resource identified by the request is only capable of"
+        " generating response entities which have content"
+        " characteristics not acceptable according to the accept"
+        " headers sent in the request."
+    )
+
+
+class RequestTimeout(HTTPException):
+    """*408* `Request Timeout`
+
+    Raise to signalize a timeout.
+    """
+
+    code = 408
+    description = (
+        "The server closed the network connection because the browser"
+        " didn't finish the request within the specified time."
+    )
+
+
+class Conflict(HTTPException):
+    """*409* `Conflict`
+
+    Raise to signal that a request cannot be completed because it conflicts
+    with the current state on the server.
+
+    .. versionadded:: 0.7
+    """
+
+    code = 409
+    description = (
+        "A conflict happened while processing the request. The"
+        " resource might have been modified while the request was being"
+        " processed."
+    )
+
+
+class Gone(HTTPException):
+    """*410* `Gone`
+
+    Raise if a resource existed previously and went away without new location.
+    """
+
+    code = 410
+    description = (
+        "The requested URL is no longer available on this server and"
+        " there is no forwarding address. If you followed a link from a"
+        " foreign page, please contact the author of this page."
+    )
+
+
+class LengthRequired(HTTPException):
+    """*411* `Length Required`
+
+    Raise if the browser submitted data but no ``Content-Length`` header which
+    is required for the kind of processing the server does.
+    """
+
+    code = 411
+    description = (
+        "A request with this method requires a valid <code>Content-"
+        "Length</code> header."
+    )
+
+
+class PreconditionFailed(HTTPException):
+    """*412* `Precondition Failed`
+
+    Status code used in combination with ``If-Match``, ``If-None-Match``, or
+    ``If-Unmodified-Since``.
+    """
+
+    code = 412
+    description = (
+        "The precondition on the request for the URL failed positive evaluation."
+    )
+
+
+class RequestEntityTooLarge(HTTPException):
+    """*413* `Request Entity Too Large`
+
+    The status code one should return if the data submitted exceeded a given
+    limit.
+    """
+
+    code = 413
+    description = "The data value transmitted exceeds the capacity limit."
+
+
+class RequestURITooLarge(HTTPException):
+    """*414* `Request URI Too Large`
+
+    Like *413* but for too long URLs.
+    """
+
+    code = 414
+    description = (
+        "The length of the requested URL exceeds the capacity limit for"
+        " this server. The request cannot be processed."
+    )
+
+
+class UnsupportedMediaType(HTTPException):
+    """*415* `Unsupported Media Type`
+
+    The status code returned if the server is unable to handle the media type
+    the client transmitted.
+    """
+
+    code = 415
+    description = (
+        "The server does not support the media type transmitted in the request."
+    )
+
+
+class RequestedRangeNotSatisfiable(HTTPException):
+    """*416* `Requested Range Not Satisfiable`
+
+    The client asked for an invalid part of the file.
+
+    .. versionadded:: 0.7
+    """
+
+    code = 416
+    description = "The server cannot provide the requested range."
+
+    def __init__(self, length=None, units="bytes", description=None):
+        """Takes an optional `Content-Range` header value based on ``length``
+        parameter.
+        """
+        HTTPException.__init__(self, description)
+        self.length = length
+        self.units = units
+
+    def get_headers(self, environ=None):
+        headers = HTTPException.get_headers(self, environ)
+        if self.length is not None:
+            headers.append(("Content-Range", "%s */%d" % (self.units, self.length)))
+        return headers
+
+
+class ExpectationFailed(HTTPException):
+    """*417* `Expectation Failed`
+
+    The server cannot meet the requirements of the Expect request-header.
+
+    .. versionadded:: 0.7
+    """
+
+    code = 417
+    description = "The server could not meet the requirements of the Expect header"
+
+
+class ImATeapot(HTTPException):
+    """*418* `I'm a teapot`
+
+    The server should return this if it is a teapot and someone attempted
+    to brew coffee with it.
+
+    .. versionadded:: 0.7
+    """
+
+    code = 418
+    description = "This server is a teapot, not a coffee machine"
+
+
+class UnprocessableEntity(HTTPException):
+    """*422* `Unprocessable Entity`
+
+    Used if the request is well formed, but the instructions are otherwise
+    incorrect.
+    """
+
+    code = 422
+    description = (
+        "The request was well-formed but was unable to be followed due"
+        " to semantic errors."
+    )
+
+
+class Locked(HTTPException):
+    """*423* `Locked`
+
+    Used if the resource that is being accessed is locked.
+    """
+
+    code = 423
+    description = "The resource that is being accessed is locked."
+
+
+class FailedDependency(HTTPException):
+    """*424* `Failed Dependency`
+
+    Used if the method could not be performed on the resource
+    because the requested action depended on another action and that action failed.
+    """
+
+    code = 424
+    description = (
+        "The method could not be performed on the resource because the"
+        " requested action depended on another action and that action"
+        " failed."
+    )
+
+
+class PreconditionRequired(HTTPException):
+    """*428* `Precondition Required`
+
+    The server requires this request to be conditional, typically to prevent
+    the lost update problem, which is a race condition between two or more
+    clients attempting to update a resource through PUT or DELETE. By requiring
+    each client to include a conditional header ("If-Match" or "If-Unmodified-
+    Since") with the proper value retained from a recent GET request, the
+    server ensures that each client has at least seen the previous revision of
+    the resource.
+    """
+
+    code = 428
+    description = (
+        "This request is required to be conditional; try using"
+        ' "If-Match" or "If-Unmodified-Since".'
+    )
+
+
+class TooManyRequests(HTTPException):
+    """*429* `Too Many Requests`
+
+    The server is limiting the rate at which this user receives responses, and
+    this request exceeds that rate. (The server may use any convenient method
+    to identify users and their request rates). The server may include a
+    "Retry-After" header to indicate how long the user should wait before
+    retrying.
+    """
+
+    code = 429
+    description = "This user has exceeded an allotted request count. Try again later."
+
+
+class RequestHeaderFieldsTooLarge(HTTPException):
+    """*431* `Request Header Fields Too Large`
+
+    The server refuses to process the request because the header fields are too
+    large. One or more individual fields may be too large, or the set of all
+    headers is too large.
+    """
+
+    code = 431
+    description = "One or more header fields exceeds the maximum size."
+
+
+class UnavailableForLegalReasons(HTTPException):
+    """*451* `Unavailable For Legal Reasons`
+
+    This status code indicates that the server is denying access to the
+    resource as a consequence of a legal demand.
+    """
+
+    code = 451
+    description = "Unavailable for legal reasons."
+
+
+class InternalServerError(HTTPException):
+    """*500* `Internal Server Error`
+
+    Raise if an internal server error occurred.  This is a good fallback if an
+    unknown error occurred in the dispatcher.
+    """
+
+    code = 500
+    description = (
+        "The server encountered an internal error and was unable to"
+        " complete your request. Either the server is overloaded or"
+        " there is an error in the application."
+    )
+
+
+class NotImplemented(HTTPException):
+    """*501* `Not Implemented`
+
+    Raise if the application does not support the action requested by the
+    browser.
+    """
+
+    code = 501
+    description = "The server does not support the action requested by the browser."
+
+
+class BadGateway(HTTPException):
+    """*502* `Bad Gateway`
+
+    If you do proxying in your application you should return this status code
+    if you received an invalid response from the upstream server it accessed
+    in attempting to fulfill the request.
+    """
+
+    code = 502
+    description = (
+        "The proxy server received an invalid response from an upstream server."
+    )
+
+
+class ServiceUnavailable(HTTPException):
+    """*503* `Service Unavailable`
+
+    Status code you should return if a service is temporarily unavailable.
+    """
+
+    code = 503
+    description = (
+        "The server is temporarily unable to service your request due"
+        " to maintenance downtime or capacity problems. Please try"
+        " again later."
+    )
+
+
+class GatewayTimeout(HTTPException):
+    """*504* `Gateway Timeout`
+
+    Status code you should return if a connection to an upstream server
+    times out.
+    """
+
+    code = 504
+    description = "The connection to an upstream server timed out."
+
+
+class HTTPVersionNotSupported(HTTPException):
+    """*505* `HTTP Version Not Supported`
+
+    The server does not support the HTTP protocol version used in the request.
+    """
+
+    code = 505
+    description = (
+        "The server does not support the HTTP protocol version used in the request."
+    )
+
+
+default_exceptions = {}
+__all__ = ["HTTPException"]
+
+
+def _find_exceptions():
+    for _name, obj in iteritems(globals()):
+        try:
+            is_http_exception = issubclass(obj, HTTPException)
+        except TypeError:
+            is_http_exception = False
+        if not is_http_exception or obj.code is None:
+            continue
+        __all__.append(obj.__name__)
+        old_obj = default_exceptions.get(obj.code, None)
+        if old_obj is not None and issubclass(obj, old_obj):
+            continue
+        default_exceptions[obj.code] = obj
+
+
+_find_exceptions()
+del _find_exceptions
+
+
+class Aborter(object):
+    """When passed a dict of code -> exception items it can be used as
+    callable that raises exceptions.  If the first argument to the
+    callable is an integer it will be looked up in the mapping, if it's
+    a WSGI application it will be raised in a proxy exception.
+
+    The rest of the arguments are forwarded to the exception constructor.
+    """
+
+    def __init__(self, mapping=None, extra=None):
+        if mapping is None:
+            mapping = default_exceptions
+        self.mapping = dict(mapping)
+        if extra is not None:
+            self.mapping.update(extra)
+
+    def __call__(self, code, *args, **kwargs):
+        if not args and not kwargs and not isinstance(code, integer_types):
+            raise HTTPException(response=code)
+        if code not in self.mapping:
+            raise LookupError("no exception for %r" % code)
+        raise self.mapping[code](*args, **kwargs)
+
+
+def abort(status, *args, **kwargs):
+    """Raises an :py:exc:`HTTPException` for the given status code or WSGI
+    application::
+
+        abort(404)  # 404 Not Found
+        abort(Response('Hello World'))
+
+    Can be passed a WSGI application or a status code.  If a status code is
+    given it's looked up in the list of exceptions and will raise that
+    exception, if passed a WSGI application it will wrap it in a proxy WSGI
+    exception and raise that::
+
+       abort(404)
+       abort(Response('Hello World'))
+
+    """
+    return _aborter(status, *args, **kwargs)
+
+
+_aborter = Aborter()
+
+
+#: an exception that is used internally to signal both a key error and a
+#: bad request.  Used by a lot of the datastructures.
+BadRequestKeyError = BadRequest.wrap(KeyError)
+
+# imported here because of circular dependencies of werkzeug.utils
+from .http import HTTP_STATUS_CODES
+from .utils import escape
diff --git a/python/werkzeug/filesystem.py b/python/werkzeug/filesystem.py
new file mode 100644
index 0000000..d016cae
--- /dev/null
+++ b/python/werkzeug/filesystem.py
@@ -0,0 +1,64 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.filesystem
+    ~~~~~~~~~~~~~~~~~~~
+
+    Various utilities for the local filesystem.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import sys
+import warnings
+
+# We do not trust traditional unixes.
+has_likely_buggy_unicode_filesystem = (
+    sys.platform.startswith("linux") or "bsd" in sys.platform
+)
+
+
+def _is_ascii_encoding(encoding):
+    """Given an encoding this figures out if the encoding is actually ASCII (which
+    is something we don't actually want in most cases). This is necessary
+    because ASCII comes under many names such as ANSI_X3.4-1968.
+    """
+    if encoding is None:
+        return False
+    try:
+        return codecs.lookup(encoding).name == "ascii"
+    except LookupError:
+        return False
+
+
+class BrokenFilesystemWarning(RuntimeWarning, UnicodeWarning):
+    """The warning used by Werkzeug to signal a broken filesystem. Will only be
+    used once per runtime."""
+
+
+_warned_about_filesystem_encoding = False
+
+
+def get_filesystem_encoding():
+    """Returns the filesystem encoding that should be used. Note that this is
+    different from the Python understanding of the filesystem encoding which
+    might be deeply flawed. Do not use this value against Python's unicode APIs
+    because it might be different. See :ref:`filesystem-encoding` for the exact
+    behavior.
+
+    The concept of a filesystem encoding in generally is not something you
+    should rely on. As such if you ever need to use this function except for
+    writing wrapper code reconsider.
+    """
+    global _warned_about_filesystem_encoding
+    rv = sys.getfilesystemencoding()
+    if has_likely_buggy_unicode_filesystem and not rv or _is_ascii_encoding(rv):
+        if not _warned_about_filesystem_encoding:
+            warnings.warn(
+                "Detected a misconfigured UNIX filesystem: Will use"
+                " UTF-8 as filesystem encoding instead of {0!r}".format(rv),
+                BrokenFilesystemWarning,
+            )
+            _warned_about_filesystem_encoding = True
+        return "utf-8"
+    return rv
diff --git a/python/werkzeug/formparser.py b/python/werkzeug/formparser.py
new file mode 100644
index 0000000..0ddc5c8
--- /dev/null
+++ b/python/werkzeug/formparser.py
@@ -0,0 +1,586 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.formparser
+    ~~~~~~~~~~~~~~~~~~~
+
+    This module implements the form parsing.  It supports url-encoded forms
+    as well as non-nested multipart uploads.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import re
+from functools import update_wrapper
+from itertools import chain
+from itertools import repeat
+from itertools import tee
+
+from ._compat import BytesIO
+from ._compat import text_type
+from ._compat import to_native
+from .datastructures import FileStorage
+from .datastructures import Headers
+from .datastructures import MultiDict
+from .http import parse_options_header
+from .urls import url_decode_stream
+from .wsgi import get_content_length
+from .wsgi import get_input_stream
+from .wsgi import make_line_iter
+
+# there are some platforms where SpooledTemporaryFile is not available.
+# In that case we need to provide a fallback.
+try:
+    from tempfile import SpooledTemporaryFile
+except ImportError:
+    from tempfile import TemporaryFile
+
+    SpooledTemporaryFile = None
+
+
+#: an iterator that yields empty strings
+_empty_string_iter = repeat("")
+
+#: a regular expression for multipart boundaries
+_multipart_boundary_re = re.compile("^[ -~]{0,200}[!-~]$")
+
+#: supported http encodings that are also available in python we support
+#: for multipart messages.
+_supported_multipart_encodings = frozenset(["base64", "quoted-printable"])
+
+
+def default_stream_factory(
+    total_content_length, filename, content_type, content_length=None
+):
+    """The stream factory that is used per default."""
+    max_size = 1024 * 500
+    if SpooledTemporaryFile is not None:
+        return SpooledTemporaryFile(max_size=max_size, mode="wb+")
+    if total_content_length is None or total_content_length > max_size:
+        return TemporaryFile("wb+")
+    return BytesIO()
+
+
+def parse_form_data(
+    environ,
+    stream_factory=None,
+    charset="utf-8",
+    errors="replace",
+    max_form_memory_size=None,
+    max_content_length=None,
+    cls=None,
+    silent=True,
+):
+    """Parse the form data in the environ and return it as tuple in the form
+    ``(stream, form, files)``.  You should only call this method if the
+    transport method is `POST`, `PUT`, or `PATCH`.
+
+    If the mimetype of the data transmitted is `multipart/form-data` the
+    files multidict will be filled with `FileStorage` objects.  If the
+    mimetype is unknown the input stream is wrapped and returned as first
+    argument, else the stream is empty.
+
+    This is a shortcut for the common usage of :class:`FormDataParser`.
+
+    Have a look at :ref:`dealing-with-request-data` for more details.
+
+    .. versionadded:: 0.5
+       The `max_form_memory_size`, `max_content_length` and
+       `cls` parameters were added.
+
+    .. versionadded:: 0.5.1
+       The optional `silent` flag was added.
+
+    :param environ: the WSGI environment to be used for parsing.
+    :param stream_factory: An optional callable that returns a new read and
+                           writeable file descriptor.  This callable works
+                           the same as :meth:`~BaseResponse._get_file_stream`.
+    :param charset: The character set for URL and url encoded form data.
+    :param errors: The encoding error behavior.
+    :param max_form_memory_size: the maximum number of bytes to be accepted for
+                           in-memory stored form data.  If the data
+                           exceeds the value specified an
+                           :exc:`~exceptions.RequestEntityTooLarge`
+                           exception is raised.
+    :param max_content_length: If this is provided and the transmitted data
+                               is longer than this value an
+                               :exc:`~exceptions.RequestEntityTooLarge`
+                               exception is raised.
+    :param cls: an optional dict class to use.  If this is not specified
+                       or `None` the default :class:`MultiDict` is used.
+    :param silent: If set to False parsing errors will not be caught.
+    :return: A tuple in the form ``(stream, form, files)``.
+    """
+    return FormDataParser(
+        stream_factory,
+        charset,
+        errors,
+        max_form_memory_size,
+        max_content_length,
+        cls,
+        silent,
+    ).parse_from_environ(environ)
+
+
+def exhaust_stream(f):
+    """Helper decorator for methods that exhausts the stream on return."""
+
+    def wrapper(self, stream, *args, **kwargs):
+        try:
+            return f(self, stream, *args, **kwargs)
+        finally:
+            exhaust = getattr(stream, "exhaust", None)
+            if exhaust is not None:
+                exhaust()
+            else:
+                while 1:
+                    chunk = stream.read(1024 * 64)
+                    if not chunk:
+                        break
+
+    return update_wrapper(wrapper, f)
+
+
+class FormDataParser(object):
+    """This class implements parsing of form data for Werkzeug.  By itself
+    it can parse multipart and url encoded form data.  It can be subclassed
+    and extended but for most mimetypes it is a better idea to use the
+    untouched stream and expose it as separate attributes on a request
+    object.
+
+    .. versionadded:: 0.8
+
+    :param stream_factory: An optional callable that returns a new read and
+                           writeable file descriptor.  This callable works
+                           the same as :meth:`~BaseResponse._get_file_stream`.
+    :param charset: The character set for URL and url encoded form data.
+    :param errors: The encoding error behavior.
+    :param max_form_memory_size: the maximum number of bytes to be accepted for
+                           in-memory stored form data.  If the data
+                           exceeds the value specified an
+                           :exc:`~exceptions.RequestEntityTooLarge`
+                           exception is raised.
+    :param max_content_length: If this is provided and the transmitted data
+                               is longer than this value an
+                               :exc:`~exceptions.RequestEntityTooLarge`
+                               exception is raised.
+    :param cls: an optional dict class to use.  If this is not specified
+                       or `None` the default :class:`MultiDict` is used.
+    :param silent: If set to False parsing errors will not be caught.
+    """
+
+    def __init__(
+        self,
+        stream_factory=None,
+        charset="utf-8",
+        errors="replace",
+        max_form_memory_size=None,
+        max_content_length=None,
+        cls=None,
+        silent=True,
+    ):
+        if stream_factory is None:
+            stream_factory = default_stream_factory
+        self.stream_factory = stream_factory
+        self.charset = charset
+        self.errors = errors
+        self.max_form_memory_size = max_form_memory_size
+        self.max_content_length = max_content_length
+        if cls is None:
+            cls = MultiDict
+        self.cls = cls
+        self.silent = silent
+
+    def get_parse_func(self, mimetype, options):
+        return self.parse_functions.get(mimetype)
+
+    def parse_from_environ(self, environ):
+        """Parses the information from the environment as form data.
+
+        :param environ: the WSGI environment to be used for parsing.
+        :return: A tuple in the form ``(stream, form, files)``.
+        """
+        content_type = environ.get("CONTENT_TYPE", "")
+        content_length = get_content_length(environ)
+        mimetype, options = parse_options_header(content_type)
+        return self.parse(get_input_stream(environ), mimetype, content_length, options)
+
+    def parse(self, stream, mimetype, content_length, options=None):
+        """Parses the information from the given stream, mimetype,
+        content length and mimetype parameters.
+
+        :param stream: an input stream
+        :param mimetype: the mimetype of the data
+        :param content_length: the content length of the incoming data
+        :param options: optional mimetype parameters (used for
+                        the multipart boundary for instance)
+        :return: A tuple in the form ``(stream, form, files)``.
+        """
+        if (
+            self.max_content_length is not None
+            and content_length is not None
+            and content_length > self.max_content_length
+        ):
+            raise exceptions.RequestEntityTooLarge()
+        if options is None:
+            options = {}
+
+        parse_func = self.get_parse_func(mimetype, options)
+        if parse_func is not None:
+            try:
+                return parse_func(self, stream, mimetype, content_length, options)
+            except ValueError:
+                if not self.silent:
+                    raise
+
+        return stream, self.cls(), self.cls()
+
+    @exhaust_stream
+    def _parse_multipart(self, stream, mimetype, content_length, options):
+        parser = MultiPartParser(
+            self.stream_factory,
+            self.charset,
+            self.errors,
+            max_form_memory_size=self.max_form_memory_size,
+            cls=self.cls,
+        )
+        boundary = options.get("boundary")
+        if boundary is None:
+            raise ValueError("Missing boundary")
+        if isinstance(boundary, text_type):
+            boundary = boundary.encode("ascii")
+        form, files = parser.parse(stream, boundary, content_length)
+        return stream, form, files
+
+    @exhaust_stream
+    def _parse_urlencoded(self, stream, mimetype, content_length, options):
+        if (
+            self.max_form_memory_size is not None
+            and content_length is not None
+            and content_length > self.max_form_memory_size
+        ):
+            raise exceptions.RequestEntityTooLarge()
+        form = url_decode_stream(stream, self.charset, errors=self.errors, cls=self.cls)
+        return stream, form, self.cls()
+
+    #: mapping of mimetypes to parsing functions
+    parse_functions = {
+        "multipart/form-data": _parse_multipart,
+        "application/x-www-form-urlencoded": _parse_urlencoded,
+        "application/x-url-encoded": _parse_urlencoded,
+    }
+
+
+def is_valid_multipart_boundary(boundary):
+    """Checks if the string given is a valid multipart boundary."""
+    return _multipart_boundary_re.match(boundary) is not None
+
+
+def _line_parse(line):
+    """Removes line ending characters and returns a tuple (`stripped_line`,
+    `is_terminated`).
+    """
+    if line[-2:] in ["\r\n", b"\r\n"]:
+        return line[:-2], True
+    elif line[-1:] in ["\r", "\n", b"\r", b"\n"]:
+        return line[:-1], True
+    return line, False
+
+
+def parse_multipart_headers(iterable):
+    """Parses multipart headers from an iterable that yields lines (including
+    the trailing newline symbol).  The iterable has to be newline terminated.
+
+    The iterable will stop at the line where the headers ended so it can be
+    further consumed.
+
+    :param iterable: iterable of strings that are newline terminated
+    """
+    result = []
+    for line in iterable:
+        line = to_native(line)
+        line, line_terminated = _line_parse(line)
+        if not line_terminated:
+            raise ValueError("unexpected end of line in multipart header")
+        if not line:
+            break
+        elif line[0] in " \t" and result:
+            key, value = result[-1]
+            result[-1] = (key, value + "\n " + line[1:])
+        else:
+            parts = line.split(":", 1)
+            if len(parts) == 2:
+                result.append((parts[0].strip(), parts[1].strip()))
+
+    # we link the list to the headers, no need to create a copy, the
+    # list was not shared anyways.
+    return Headers(result)
+
+
+_begin_form = "begin_form"
+_begin_file = "begin_file"
+_cont = "cont"
+_end = "end"
+
+
+class MultiPartParser(object):
+    def __init__(
+        self,
+        stream_factory=None,
+        charset="utf-8",
+        errors="replace",
+        max_form_memory_size=None,
+        cls=None,
+        buffer_size=64 * 1024,
+    ):
+        self.charset = charset
+        self.errors = errors
+        self.max_form_memory_size = max_form_memory_size
+        self.stream_factory = (
+            default_stream_factory if stream_factory is None else stream_factory
+        )
+        self.cls = MultiDict if cls is None else cls
+
+        # make sure the buffer size is divisible by four so that we can base64
+        # decode chunk by chunk
+        assert buffer_size % 4 == 0, "buffer size has to be divisible by 4"
+        # also the buffer size has to be at least 1024 bytes long or long headers
+        # will freak out the system
+        assert buffer_size >= 1024, "buffer size has to be at least 1KB"
+
+        self.buffer_size = buffer_size
+
+    def _fix_ie_filename(self, filename):
+        """Internet Explorer 6 transmits the full file name if a file is
+        uploaded.  This function strips the full path if it thinks the
+        filename is Windows-like absolute.
+        """
+        if filename[1:3] == ":\\" or filename[:2] == "\\\\":
+            return filename.split("\\")[-1]
+        return filename
+
+    def _find_terminator(self, iterator):
+        """The terminator might have some additional newlines before it.
+        There is at least one application that sends additional newlines
+        before headers (the python setuptools package).
+        """
+        for line in iterator:
+            if not line:
+                break
+            line = line.strip()
+            if line:
+                return line
+        return b""
+
+    def fail(self, message):
+        raise ValueError(message)
+
+    def get_part_encoding(self, headers):
+        transfer_encoding = headers.get("content-transfer-encoding")
+        if (
+            transfer_encoding is not None
+            and transfer_encoding in _supported_multipart_encodings
+        ):
+            return transfer_encoding
+
+    def get_part_charset(self, headers):
+        # Figure out input charset for current part
+        content_type = headers.get("content-type")
+        if content_type:
+            mimetype, ct_params = parse_options_header(content_type)
+            return ct_params.get("charset", self.charset)
+        return self.charset
+
+    def start_file_streaming(self, filename, headers, total_content_length):
+        if isinstance(filename, bytes):
+            filename = filename.decode(self.charset, self.errors)
+        filename = self._fix_ie_filename(filename)
+        content_type = headers.get("content-type")
+        try:
+            content_length = int(headers["content-length"])
+        except (KeyError, ValueError):
+            content_length = 0
+        container = self.stream_factory(
+            total_content_length=total_content_length,
+            filename=filename,
+            content_type=content_type,
+            content_length=content_length,
+        )
+        return filename, container
+
+    def in_memory_threshold_reached(self, bytes):
+        raise exceptions.RequestEntityTooLarge()
+
+    def validate_boundary(self, boundary):
+        if not boundary:
+            self.fail("Missing boundary")
+        if not is_valid_multipart_boundary(boundary):
+            self.fail("Invalid boundary: %s" % boundary)
+        if len(boundary) > self.buffer_size:  # pragma: no cover
+            # this should never happen because we check for a minimum size
+            # of 1024 and boundaries may not be longer than 200.  The only
+            # situation when this happens is for non debug builds where
+            # the assert is skipped.
+            self.fail("Boundary longer than buffer size")
+
+    def parse_lines(self, file, boundary, content_length, cap_at_buffer=True):
+        """Generate parts of
+        ``('begin_form', (headers, name))``
+        ``('begin_file', (headers, name, filename))``
+        ``('cont', bytestring)``
+        ``('end', None)``
+
+        Always obeys the grammar
+        parts = ( begin_form cont* end |
+                  begin_file cont* end )*
+        """
+        next_part = b"--" + boundary
+        last_part = next_part + b"--"
+
+        iterator = chain(
+            make_line_iter(
+                file,
+                limit=content_length,
+                buffer_size=self.buffer_size,
+                cap_at_buffer=cap_at_buffer,
+            ),
+            _empty_string_iter,
+        )
+
+        terminator = self._find_terminator(iterator)
+
+        if terminator == last_part:
+            return
+        elif terminator != next_part:
+            self.fail("Expected boundary at start of multipart data")
+
+        while terminator != last_part:
+            headers = parse_multipart_headers(iterator)
+
+            disposition = headers.get("content-disposition")
+            if disposition is None:
+                self.fail("Missing Content-Disposition header")
+            disposition, extra = parse_options_header(disposition)
+            transfer_encoding = self.get_part_encoding(headers)
+            name = extra.get("name")
+            filename = extra.get("filename")
+
+            # if no content type is given we stream into memory.  A list is
+            # used as a temporary container.
+            if filename is None:
+                yield _begin_form, (headers, name)
+
+            # otherwise we parse the rest of the headers and ask the stream
+            # factory for something we can write in.
+            else:
+                yield _begin_file, (headers, name, filename)
+
+            buf = b""
+            for line in iterator:
+                if not line:
+                    self.fail("unexpected end of stream")
+
+                if line[:2] == b"--":
+                    terminator = line.rstrip()
+                    if terminator in (next_part, last_part):
+                        break
+
+                if transfer_encoding is not None:
+                    if transfer_encoding == "base64":
+                        transfer_encoding = "base64_codec"
+                    try:
+                        line = codecs.decode(line, transfer_encoding)
+                    except Exception:
+                        self.fail("could not decode transfer encoded chunk")
+
+                # we have something in the buffer from the last iteration.
+                # this is usually a newline delimiter.
+                if buf:
+                    yield _cont, buf
+                    buf = b""
+
+                # If the line ends with windows CRLF we write everything except
+                # the last two bytes.  In all other cases however we write
+                # everything except the last byte.  If it was a newline, that's
+                # fine, otherwise it does not matter because we will write it
+                # the next iteration.  this ensures we do not write the
+                # final newline into the stream.  That way we do not have to
+                # truncate the stream.  However we do have to make sure that
+                # if something else than a newline is in there we write it
+                # out.
+                if line[-2:] == b"\r\n":
+                    buf = b"\r\n"
+                    cutoff = -2
+                else:
+                    buf = line[-1:]
+                    cutoff = -1
+                yield _cont, line[:cutoff]
+
+            else:  # pragma: no cover
+                raise ValueError("unexpected end of part")
+
+            # if we have a leftover in the buffer that is not a newline
+            # character we have to flush it, otherwise we will chop of
+            # certain values.
+            if buf not in (b"", b"\r", b"\n", b"\r\n"):
+                yield _cont, buf
+
+            yield _end, None
+
+    def parse_parts(self, file, boundary, content_length):
+        """Generate ``('file', (name, val))`` and
+        ``('form', (name, val))`` parts.
+        """
+        in_memory = 0
+
+        for ellt, ell in self.parse_lines(file, boundary, content_length):
+            if ellt == _begin_file:
+                headers, name, filename = ell
+                is_file = True
+                guard_memory = False
+                filename, container = self.start_file_streaming(
+                    filename, headers, content_length
+                )
+                _write = container.write
+
+            elif ellt == _begin_form:
+                headers, name = ell
+                is_file = False
+                container = []
+                _write = container.append
+                guard_memory = self.max_form_memory_size is not None
+
+            elif ellt == _cont:
+                _write(ell)
+                # if we write into memory and there is a memory size limit we
+                # count the number of bytes in memory and raise an exception if
+                # there is too much data in memory.
+                if guard_memory:
+                    in_memory += len(ell)
+                    if in_memory > self.max_form_memory_size:
+                        self.in_memory_threshold_reached(in_memory)
+
+            elif ellt == _end:
+                if is_file:
+                    container.seek(0)
+                    yield (
+                        "file",
+                        (name, FileStorage(container, filename, name, headers=headers)),
+                    )
+                else:
+                    part_charset = self.get_part_charset(headers)
+                    yield (
+                        "form",
+                        (name, b"".join(container).decode(part_charset, self.errors)),
+                    )
+
+    def parse(self, file, boundary, content_length):
+        formstream, filestream = tee(
+            self.parse_parts(file, boundary, content_length), 2
+        )
+        form = (p[1] for p in formstream if p[0] == "form")
+        files = (p[1] for p in filestream if p[0] == "file")
+        return self.cls(form), self.cls(files)
+
+
+from . import exceptions
diff --git a/python/werkzeug/http.py b/python/werkzeug/http.py
new file mode 100644
index 0000000..af32007
--- /dev/null
+++ b/python/werkzeug/http.py
@@ -0,0 +1,1303 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.http
+    ~~~~~~~~~~~~~
+
+    Werkzeug comes with a bunch of utilities that help Werkzeug to deal with
+    HTTP data.  Most of the classes and functions provided by this module are
+    used by the wrappers, but they are useful on their own, too, especially if
+    the response and request objects are not used.
+
+    This covers some of the more HTTP centric features of WSGI, some other
+    utilities such as cookie handling are documented in the `werkzeug.utils`
+    module.
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import base64
+import re
+import warnings
+from datetime import datetime
+from datetime import timedelta
+from hashlib import md5
+from time import gmtime
+from time import time
+
+from ._compat import integer_types
+from ._compat import iteritems
+from ._compat import PY2
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import to_bytes
+from ._compat import to_unicode
+from ._compat import try_coerce_native
+from ._internal import _cookie_parse_impl
+from ._internal import _cookie_quote
+from ._internal import _make_cookie_domain
+
+try:
+    from email.utils import parsedate_tz
+except ImportError:
+    from email.Utils import parsedate_tz
+
+try:
+    from urllib.request import parse_http_list as _parse_list_header
+    from urllib.parse import unquote_to_bytes as _unquote
+except ImportError:
+    from urllib2 import parse_http_list as _parse_list_header
+    from urllib2 import unquote as _unquote
+
+_cookie_charset = "latin1"
+_basic_auth_charset = "utf-8"
+# for explanation of "media-range", etc. see Sections 5.3.{1,2} of RFC 7231
+_accept_re = re.compile(
+    r"""
+    (                       # media-range capturing-parenthesis
+      [^\s;,]+              # type/subtype
+      (?:[ \t]*;[ \t]*      # ";"
+        (?:                 # parameter non-capturing-parenthesis
+          [^\s;,q][^\s;,]*  # token that doesn't start with "q"
+        |                   # or
+          q[^\s;,=][^\s;,]* # token that is more than just "q"
+        )
+      )*                    # zero or more parameters
+    )                       # end of media-range
+    (?:[ \t]*;[ \t]*q=      # weight is a "q" parameter
+      (\d*(?:\.\d+)?)       # qvalue capturing-parentheses
+      [^,]*                 # "extension" accept params: who cares?
+    )?                      # accept params are optional
+    """,
+    re.VERBOSE,
+)
+_token_chars = frozenset(
+    "!#$%&'*+-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ^_`abcdefghijklmnopqrstuvwxyz|~"
+)
+_etag_re = re.compile(r'([Ww]/)?(?:"(.*?)"|(.*?))(?:\s*,\s*|$)')
+_unsafe_header_chars = set('()<>@,;:"/[]?={} \t')
+_option_header_piece_re = re.compile(
+    r"""
+    ;\s*,?\s*  # newlines were replaced with commas
+    (?P<key>
+        "[^"\\]*(?:\\.[^"\\]*)*"  # quoted string
+    |
+        [^\s;,=*]+  # token
+    )
+    (?:\*(?P<count>\d+))?  # *1, optional continuation index
+    \s*
+    (?:  # optionally followed by =value
+        (?:  # equals sign, possibly with encoding
+            \*\s*=\s*  # * indicates extended notation
+            (?:  # optional encoding
+                (?P<encoding>[^\s]+?)
+                '(?P<language>[^\s]*?)'
+            )?
+        |
+            =\s*  # basic notation
+        )
+        (?P<value>
+            "[^"\\]*(?:\\.[^"\\]*)*"  # quoted string
+        |
+            [^;,]+  # token
+        )?
+    )?
+    \s*
+    """,
+    flags=re.VERBOSE,
+)
+_option_header_start_mime_type = re.compile(r",\s*([^;,\s]+)([;,]\s*.+)?")
+
+_entity_headers = frozenset(
+    [
+        "allow",
+        "content-encoding",
+        "content-language",
+        "content-length",
+        "content-location",
+        "content-md5",
+        "content-range",
+        "content-type",
+        "expires",
+        "last-modified",
+    ]
+)
+_hop_by_hop_headers = frozenset(
+    [
+        "connection",
+        "keep-alive",
+        "proxy-authenticate",
+        "proxy-authorization",
+        "te",
+        "trailer",
+        "transfer-encoding",
+        "upgrade",
+    ]
+)
+
+
+HTTP_STATUS_CODES = {
+    100: "Continue",
+    101: "Switching Protocols",
+    102: "Processing",
+    200: "OK",
+    201: "Created",
+    202: "Accepted",
+    203: "Non Authoritative Information",
+    204: "No Content",
+    205: "Reset Content",
+    206: "Partial Content",
+    207: "Multi Status",
+    226: "IM Used",  # see RFC 3229
+    300: "Multiple Choices",
+    301: "Moved Permanently",
+    302: "Found",
+    303: "See Other",
+    304: "Not Modified",
+    305: "Use Proxy",
+    307: "Temporary Redirect",
+    308: "Permanent Redirect",
+    400: "Bad Request",
+    401: "Unauthorized",
+    402: "Payment Required",  # unused
+    403: "Forbidden",
+    404: "Not Found",
+    405: "Method Not Allowed",
+    406: "Not Acceptable",
+    407: "Proxy Authentication Required",
+    408: "Request Timeout",
+    409: "Conflict",
+    410: "Gone",
+    411: "Length Required",
+    412: "Precondition Failed",
+    413: "Request Entity Too Large",
+    414: "Request URI Too Long",
+    415: "Unsupported Media Type",
+    416: "Requested Range Not Satisfiable",
+    417: "Expectation Failed",
+    418: "I'm a teapot",  # see RFC 2324
+    421: "Misdirected Request",  # see RFC 7540
+    422: "Unprocessable Entity",
+    423: "Locked",
+    424: "Failed Dependency",
+    426: "Upgrade Required",
+    428: "Precondition Required",  # see RFC 6585
+    429: "Too Many Requests",
+    431: "Request Header Fields Too Large",
+    449: "Retry With",  # proprietary MS extension
+    451: "Unavailable For Legal Reasons",
+    500: "Internal Server Error",
+    501: "Not Implemented",
+    502: "Bad Gateway",
+    503: "Service Unavailable",
+    504: "Gateway Timeout",
+    505: "HTTP Version Not Supported",
+    507: "Insufficient Storage",
+    510: "Not Extended",
+}
+
+
+def wsgi_to_bytes(data):
+    """coerce wsgi unicode represented bytes to real ones"""
+    if isinstance(data, bytes):
+        return data
+    return data.encode("latin1")  # XXX: utf8 fallback?
+
+
+def bytes_to_wsgi(data):
+    assert isinstance(data, bytes), "data must be bytes"
+    if isinstance(data, str):
+        return data
+    else:
+        return data.decode("latin1")
+
+
+def quote_header_value(value, extra_chars="", allow_token=True):
+    """Quote a header value if necessary.
+
+    .. versionadded:: 0.5
+
+    :param value: the value to quote.
+    :param extra_chars: a list of extra characters to skip quoting.
+    :param allow_token: if this is enabled token values are returned
+                        unchanged.
+    """
+    if isinstance(value, bytes):
+        value = bytes_to_wsgi(value)
+    value = str(value)
+    if allow_token:
+        token_chars = _token_chars | set(extra_chars)
+        if set(value).issubset(token_chars):
+            return value
+    return '"%s"' % value.replace("\\", "\\\\").replace('"', '\\"')
+
+
+def unquote_header_value(value, is_filename=False):
+    r"""Unquotes a header value.  (Reversal of :func:`quote_header_value`).
+    This does not use the real unquoting but what browsers are actually
+    using for quoting.
+
+    .. versionadded:: 0.5
+
+    :param value: the header value to unquote.
+    """
+    if value and value[0] == value[-1] == '"':
+        # this is not the real unquoting, but fixing this so that the
+        # RFC is met will result in bugs with internet explorer and
+        # probably some other browsers as well.  IE for example is
+        # uploading files with "C:\foo\bar.txt" as filename
+        value = value[1:-1]
+
+        # if this is a filename and the starting characters look like
+        # a UNC path, then just return the value without quotes.  Using the
+        # replace sequence below on a UNC path has the effect of turning
+        # the leading double slash into a single slash and then
+        # _fix_ie_filename() doesn't work correctly.  See #458.
+        if not is_filename or value[:2] != "\\\\":
+            return value.replace("\\\\", "\\").replace('\\"', '"')
+    return value
+
+
+def dump_options_header(header, options):
+    """The reverse function to :func:`parse_options_header`.
+
+    :param header: the header to dump
+    :param options: a dict of options to append.
+    """
+    segments = []
+    if header is not None:
+        segments.append(header)
+    for key, value in iteritems(options):
+        if value is None:
+            segments.append(key)
+        else:
+            segments.append("%s=%s" % (key, quote_header_value(value)))
+    return "; ".join(segments)
+
+
+def dump_header(iterable, allow_token=True):
+    """Dump an HTTP header again.  This is the reversal of
+    :func:`parse_list_header`, :func:`parse_set_header` and
+    :func:`parse_dict_header`.  This also quotes strings that include an
+    equals sign unless you pass it as dict of key, value pairs.
+
+    >>> dump_header({'foo': 'bar baz'})
+    'foo="bar baz"'
+    >>> dump_header(('foo', 'bar baz'))
+    'foo, "bar baz"'
+
+    :param iterable: the iterable or dict of values to quote.
+    :param allow_token: if set to `False` tokens as values are disallowed.
+                        See :func:`quote_header_value` for more details.
+    """
+    if isinstance(iterable, dict):
+        items = []
+        for key, value in iteritems(iterable):
+            if value is None:
+                items.append(key)
+            else:
+                items.append(
+                    "%s=%s" % (key, quote_header_value(value, allow_token=allow_token))
+                )
+    else:
+        items = [quote_header_value(x, allow_token=allow_token) for x in iterable]
+    return ", ".join(items)
+
+
+def parse_list_header(value):
+    """Parse lists as described by RFC 2068 Section 2.
+
+    In particular, parse comma-separated lists where the elements of
+    the list may include quoted-strings.  A quoted-string could
+    contain a comma.  A non-quoted string could have quotes in the
+    middle.  Quotes are removed automatically after parsing.
+
+    It basically works like :func:`parse_set_header` just that items
+    may appear multiple times and case sensitivity is preserved.
+
+    The return value is a standard :class:`list`:
+
+    >>> parse_list_header('token, "quoted value"')
+    ['token', 'quoted value']
+
+    To create a header from the :class:`list` again, use the
+    :func:`dump_header` function.
+
+    :param value: a string with a list header.
+    :return: :class:`list`
+    """
+    result = []
+    for item in _parse_list_header(value):
+        if item[:1] == item[-1:] == '"':
+            item = unquote_header_value(item[1:-1])
+        result.append(item)
+    return result
+
+
+def parse_dict_header(value, cls=dict):
+    """Parse lists of key, value pairs as described by RFC 2068 Section 2 and
+    convert them into a python dict (or any other mapping object created from
+    the type with a dict like interface provided by the `cls` argument):
+
+    >>> d = parse_dict_header('foo="is a fish", bar="as well"')
+    >>> type(d) is dict
+    True
+    >>> sorted(d.items())
+    [('bar', 'as well'), ('foo', 'is a fish')]
+
+    If there is no value for a key it will be `None`:
+
+    >>> parse_dict_header('key_without_value')
+    {'key_without_value': None}
+
+    To create a header from the :class:`dict` again, use the
+    :func:`dump_header` function.
+
+    .. versionchanged:: 0.9
+       Added support for `cls` argument.
+
+    :param value: a string with a dict header.
+    :param cls: callable to use for storage of parsed results.
+    :return: an instance of `cls`
+    """
+    result = cls()
+    if not isinstance(value, text_type):
+        # XXX: validate
+        value = bytes_to_wsgi(value)
+    for item in _parse_list_header(value):
+        if "=" not in item:
+            result[item] = None
+            continue
+        name, value = item.split("=", 1)
+        if value[:1] == value[-1:] == '"':
+            value = unquote_header_value(value[1:-1])
+        result[name] = value
+    return result
+
+
+def parse_options_header(value, multiple=False):
+    """Parse a ``Content-Type`` like header into a tuple with the content
+    type and the options:
+
+    >>> parse_options_header('text/html; charset=utf8')
+    ('text/html', {'charset': 'utf8'})
+
+    This should not be used to parse ``Cache-Control`` like headers that use
+    a slightly different format.  For these headers use the
+    :func:`parse_dict_header` function.
+
+    .. versionchanged:: 0.15
+        :rfc:`2231` parameter continuations are handled.
+
+    .. versionadded:: 0.5
+
+    :param value: the header to parse.
+    :param multiple: Whether try to parse and return multiple MIME types
+    :return: (mimetype, options) or (mimetype, options, mimetype, options, …)
+             if multiple=True
+    """
+    if not value:
+        return "", {}
+
+    result = []
+
+    value = "," + value.replace("\n", ",")
+    while value:
+        match = _option_header_start_mime_type.match(value)
+        if not match:
+            break
+        result.append(match.group(1))  # mimetype
+        options = {}
+        # Parse options
+        rest = match.group(2)
+        continued_encoding = None
+        while rest:
+            optmatch = _option_header_piece_re.match(rest)
+            if not optmatch:
+                break
+            option, count, encoding, language, option_value = optmatch.groups()
+            # Continuations don't have to supply the encoding after the
+            # first line. If we're in a continuation, track the current
+            # encoding to use for subsequent lines. Reset it when the
+            # continuation ends.
+            if not count:
+                continued_encoding = None
+            else:
+                if not encoding:
+                    encoding = continued_encoding
+                continued_encoding = encoding
+            option = unquote_header_value(option)
+            if option_value is not None:
+                option_value = unquote_header_value(option_value, option == "filename")
+                if encoding is not None:
+                    option_value = _unquote(option_value).decode(encoding)
+            if count:
+                # Continuations append to the existing value. For
+                # simplicity, this ignores the possibility of
+                # out-of-order indices, which shouldn't happen anyway.
+                options[option] = options.get(option, "") + option_value
+            else:
+                options[option] = option_value
+            rest = rest[optmatch.end() :]
+        result.append(options)
+        if multiple is False:
+            return tuple(result)
+        value = rest
+
+    return tuple(result) if result else ("", {})
+
+
+def parse_accept_header(value, cls=None):
+    """Parses an HTTP Accept-* header.  This does not implement a complete
+    valid algorithm but one that supports at least value and quality
+    extraction.
+
+    Returns a new :class:`Accept` object (basically a list of ``(value, quality)``
+    tuples sorted by the quality with some additional accessor methods).
+
+    The second parameter can be a subclass of :class:`Accept` that is created
+    with the parsed values and returned.
+
+    :param value: the accept header string to be parsed.
+    :param cls: the wrapper class for the return value (can be
+                         :class:`Accept` or a subclass thereof)
+    :return: an instance of `cls`.
+    """
+    if cls is None:
+        cls = Accept
+
+    if not value:
+        return cls(None)
+
+    result = []
+    for match in _accept_re.finditer(value):
+        quality = match.group(2)
+        if not quality:
+            quality = 1
+        else:
+            quality = max(min(float(quality), 1), 0)
+        result.append((match.group(1), quality))
+    return cls(result)
+
+
+def parse_cache_control_header(value, on_update=None, cls=None):
+    """Parse a cache control header.  The RFC differs between response and
+    request cache control, this method does not.  It's your responsibility
+    to not use the wrong control statements.
+
+    .. versionadded:: 0.5
+       The `cls` was added.  If not specified an immutable
+       :class:`~werkzeug.datastructures.RequestCacheControl` is returned.
+
+    :param value: a cache control header to be parsed.
+    :param on_update: an optional callable that is called every time a value
+                      on the :class:`~werkzeug.datastructures.CacheControl`
+                      object is changed.
+    :param cls: the class for the returned object.  By default
+                :class:`~werkzeug.datastructures.RequestCacheControl` is used.
+    :return: a `cls` object.
+    """
+    if cls is None:
+        cls = RequestCacheControl
+    if not value:
+        return cls(None, on_update)
+    return cls(parse_dict_header(value), on_update)
+
+
+def parse_set_header(value, on_update=None):
+    """Parse a set-like header and return a
+    :class:`~werkzeug.datastructures.HeaderSet` object:
+
+    >>> hs = parse_set_header('token, "quoted value"')
+
+    The return value is an object that treats the items case-insensitively
+    and keeps the order of the items:
+
+    >>> 'TOKEN' in hs
+    True
+    >>> hs.index('quoted value')
+    1
+    >>> hs
+    HeaderSet(['token', 'quoted value'])
+
+    To create a header from the :class:`HeaderSet` again, use the
+    :func:`dump_header` function.
+
+    :param value: a set header to be parsed.
+    :param on_update: an optional callable that is called every time a
+                      value on the :class:`~werkzeug.datastructures.HeaderSet`
+                      object is changed.
+    :return: a :class:`~werkzeug.datastructures.HeaderSet`
+    """
+    if not value:
+        return HeaderSet(None, on_update)
+    return HeaderSet(parse_list_header(value), on_update)
+
+
+def parse_authorization_header(value):
+    """Parse an HTTP basic/digest authorization header transmitted by the web
+    browser.  The return value is either `None` if the header was invalid or
+    not given, otherwise an :class:`~werkzeug.datastructures.Authorization`
+    object.
+
+    :param value: the authorization header to parse.
+    :return: a :class:`~werkzeug.datastructures.Authorization` object or `None`.
+    """
+    if not value:
+        return
+    value = wsgi_to_bytes(value)
+    try:
+        auth_type, auth_info = value.split(None, 1)
+        auth_type = auth_type.lower()
+    except ValueError:
+        return
+    if auth_type == b"basic":
+        try:
+            username, password = base64.b64decode(auth_info).split(b":", 1)
+        except Exception:
+            return
+        return Authorization(
+            "basic",
+            {
+                "username": to_unicode(username, _basic_auth_charset),
+                "password": to_unicode(password, _basic_auth_charset),
+            },
+        )
+    elif auth_type == b"digest":
+        auth_map = parse_dict_header(auth_info)
+        for key in "username", "realm", "nonce", "uri", "response":
+            if key not in auth_map:
+                return
+        if "qop" in auth_map:
+            if not auth_map.get("nc") or not auth_map.get("cnonce"):
+                return
+        return Authorization("digest", auth_map)
+
+
+def parse_www_authenticate_header(value, on_update=None):
+    """Parse an HTTP WWW-Authenticate header into a
+    :class:`~werkzeug.datastructures.WWWAuthenticate` object.
+
+    :param value: a WWW-Authenticate header to parse.
+    :param on_update: an optional callable that is called every time a value
+                      on the :class:`~werkzeug.datastructures.WWWAuthenticate`
+                      object is changed.
+    :return: a :class:`~werkzeug.datastructures.WWWAuthenticate` object.
+    """
+    if not value:
+        return WWWAuthenticate(on_update=on_update)
+    try:
+        auth_type, auth_info = value.split(None, 1)
+        auth_type = auth_type.lower()
+    except (ValueError, AttributeError):
+        return WWWAuthenticate(value.strip().lower(), on_update=on_update)
+    return WWWAuthenticate(auth_type, parse_dict_header(auth_info), on_update)
+
+
+def parse_if_range_header(value):
+    """Parses an if-range header which can be an etag or a date.  Returns
+    a :class:`~werkzeug.datastructures.IfRange` object.
+
+    .. versionadded:: 0.7
+    """
+    if not value:
+        return IfRange()
+    date = parse_date(value)
+    if date is not None:
+        return IfRange(date=date)
+    # drop weakness information
+    return IfRange(unquote_etag(value)[0])
+
+
+def parse_range_header(value, make_inclusive=True):
+    """Parses a range header into a :class:`~werkzeug.datastructures.Range`
+    object.  If the header is missing or malformed `None` is returned.
+    `ranges` is a list of ``(start, stop)`` tuples where the ranges are
+    non-inclusive.
+
+    .. versionadded:: 0.7
+    """
+    if not value or "=" not in value:
+        return None
+
+    ranges = []
+    last_end = 0
+    units, rng = value.split("=", 1)
+    units = units.strip().lower()
+
+    for item in rng.split(","):
+        item = item.strip()
+        if "-" not in item:
+            return None
+        if item.startswith("-"):
+            if last_end < 0:
+                return None
+            try:
+                begin = int(item)
+            except ValueError:
+                return None
+            end = None
+            last_end = -1
+        elif "-" in item:
+            begin, end = item.split("-", 1)
+            begin = begin.strip()
+            end = end.strip()
+            if not begin.isdigit():
+                return None
+            begin = int(begin)
+            if begin < last_end or last_end < 0:
+                return None
+            if end:
+                if not end.isdigit():
+                    return None
+                end = int(end) + 1
+                if begin >= end:
+                    return None
+            else:
+                end = None
+            last_end = end
+        ranges.append((begin, end))
+
+    return Range(units, ranges)
+
+
+def parse_content_range_header(value, on_update=None):
+    """Parses a range header into a
+    :class:`~werkzeug.datastructures.ContentRange` object or `None` if
+    parsing is not possible.
+
+    .. versionadded:: 0.7
+
+    :param value: a content range header to be parsed.
+    :param on_update: an optional callable that is called every time a value
+                      on the :class:`~werkzeug.datastructures.ContentRange`
+                      object is changed.
+    """
+    if value is None:
+        return None
+    try:
+        units, rangedef = (value or "").strip().split(None, 1)
+    except ValueError:
+        return None
+
+    if "/" not in rangedef:
+        return None
+    rng, length = rangedef.split("/", 1)
+    if length == "*":
+        length = None
+    elif length.isdigit():
+        length = int(length)
+    else:
+        return None
+
+    if rng == "*":
+        return ContentRange(units, None, None, length, on_update=on_update)
+    elif "-" not in rng:
+        return None
+
+    start, stop = rng.split("-", 1)
+    try:
+        start = int(start)
+        stop = int(stop) + 1
+    except ValueError:
+        return None
+
+    if is_byte_range_valid(start, stop, length):
+        return ContentRange(units, start, stop, length, on_update=on_update)
+
+
+def quote_etag(etag, weak=False):
+    """Quote an etag.
+
+    :param etag: the etag to quote.
+    :param weak: set to `True` to tag it "weak".
+    """
+    if '"' in etag:
+        raise ValueError("invalid etag")
+    etag = '"%s"' % etag
+    if weak:
+        etag = "W/" + etag
+    return etag
+
+
+def unquote_etag(etag):
+    """Unquote a single etag:
+
+    >>> unquote_etag('W/"bar"')
+    ('bar', True)
+    >>> unquote_etag('"bar"')
+    ('bar', False)
+
+    :param etag: the etag identifier to unquote.
+    :return: a ``(etag, weak)`` tuple.
+    """
+    if not etag:
+        return None, None
+    etag = etag.strip()
+    weak = False
+    if etag.startswith(("W/", "w/")):
+        weak = True
+        etag = etag[2:]
+    if etag[:1] == etag[-1:] == '"':
+        etag = etag[1:-1]
+    return etag, weak
+
+
+def parse_etags(value):
+    """Parse an etag header.
+
+    :param value: the tag header to parse
+    :return: an :class:`~werkzeug.datastructures.ETags` object.
+    """
+    if not value:
+        return ETags()
+    strong = []
+    weak = []
+    end = len(value)
+    pos = 0
+    while pos < end:
+        match = _etag_re.match(value, pos)
+        if match is None:
+            break
+        is_weak, quoted, raw = match.groups()
+        if raw == "*":
+            return ETags(star_tag=True)
+        elif quoted:
+            raw = quoted
+        if is_weak:
+            weak.append(raw)
+        else:
+            strong.append(raw)
+        pos = match.end()
+    return ETags(strong, weak)
+
+
+def generate_etag(data):
+    """Generate an etag for some data."""
+    return md5(data).hexdigest()
+
+
+def parse_date(value):
+    """Parse one of the following date formats into a datetime object:
+
+    .. sourcecode:: text
+
+        Sun, 06 Nov 1994 08:49:37 GMT  ; RFC 822, updated by RFC 1123
+        Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036
+        Sun Nov  6 08:49:37 1994       ; ANSI C's asctime() format
+
+    If parsing fails the return value is `None`.
+
+    :param value: a string with a supported date format.
+    :return: a :class:`datetime.datetime` object.
+    """
+    if value:
+        t = parsedate_tz(value.strip())
+        if t is not None:
+            try:
+                year = t[0]
+                # unfortunately that function does not tell us if two digit
+                # years were part of the string, or if they were prefixed
+                # with two zeroes.  So what we do is to assume that 69-99
+                # refer to 1900, and everything below to 2000
+                if year >= 0 and year <= 68:
+                    year += 2000
+                elif year >= 69 and year <= 99:
+                    year += 1900
+                return datetime(*((year,) + t[1:7])) - timedelta(seconds=t[-1] or 0)
+            except (ValueError, OverflowError):
+                return None
+
+
+def _dump_date(d, delim):
+    """Used for `http_date` and `cookie_date`."""
+    if d is None:
+        d = gmtime()
+    elif isinstance(d, datetime):
+        d = d.utctimetuple()
+    elif isinstance(d, (integer_types, float)):
+        d = gmtime(d)
+    return "%s, %02d%s%s%s%s %02d:%02d:%02d GMT" % (
+        ("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")[d.tm_wday],
+        d.tm_mday,
+        delim,
+        (
+            "Jan",
+            "Feb",
+            "Mar",
+            "Apr",
+            "May",
+            "Jun",
+            "Jul",
+            "Aug",
+            "Sep",
+            "Oct",
+            "Nov",
+            "Dec",
+        )[d.tm_mon - 1],
+        delim,
+        str(d.tm_year),
+        d.tm_hour,
+        d.tm_min,
+        d.tm_sec,
+    )
+
+
+def cookie_date(expires=None):
+    """Formats the time to ensure compatibility with Netscape's cookie
+    standard.
+
+    Accepts a floating point number expressed in seconds since the epoch in, a
+    datetime object or a timetuple.  All times in UTC.  The :func:`parse_date`
+    function can be used to parse such a date.
+
+    Outputs a string in the format ``Wdy, DD-Mon-YYYY HH:MM:SS GMT``.
+
+    :param expires: If provided that date is used, otherwise the current.
+    """
+    return _dump_date(expires, "-")
+
+
+def http_date(timestamp=None):
+    """Formats the time to match the RFC1123 date format.
+
+    Accepts a floating point number expressed in seconds since the epoch in, a
+    datetime object or a timetuple.  All times in UTC.  The :func:`parse_date`
+    function can be used to parse such a date.
+
+    Outputs a string in the format ``Wdy, DD Mon YYYY HH:MM:SS GMT``.
+
+    :param timestamp: If provided that date is used, otherwise the current.
+    """
+    return _dump_date(timestamp, " ")
+
+
+def parse_age(value=None):
+    """Parses a base-10 integer count of seconds into a timedelta.
+
+    If parsing fails, the return value is `None`.
+
+    :param value: a string consisting of an integer represented in base-10
+    :return: a :class:`datetime.timedelta` object or `None`.
+    """
+    if not value:
+        return None
+    try:
+        seconds = int(value)
+    except ValueError:
+        return None
+    if seconds < 0:
+        return None
+    try:
+        return timedelta(seconds=seconds)
+    except OverflowError:
+        return None
+
+
+def dump_age(age=None):
+    """Formats the duration as a base-10 integer.
+
+    :param age: should be an integer number of seconds,
+                a :class:`datetime.timedelta` object, or,
+                if the age is unknown, `None` (default).
+    """
+    if age is None:
+        return
+    if isinstance(age, timedelta):
+        # do the equivalent of Python 2.7's timedelta.total_seconds(),
+        # but disregarding fractional seconds
+        age = age.seconds + (age.days * 24 * 3600)
+
+    age = int(age)
+    if age < 0:
+        raise ValueError("age cannot be negative")
+
+    return str(age)
+
+
+def is_resource_modified(
+    environ, etag=None, data=None, last_modified=None, ignore_if_range=True
+):
+    """Convenience method for conditional requests.
+
+    :param environ: the WSGI environment of the request to be checked.
+    :param etag: the etag for the response for comparison.
+    :param data: or alternatively the data of the response to automatically
+                 generate an etag using :func:`generate_etag`.
+    :param last_modified: an optional date of the last modification.
+    :param ignore_if_range: If `False`, `If-Range` header will be taken into
+                            account.
+    :return: `True` if the resource was modified, otherwise `False`.
+    """
+    if etag is None and data is not None:
+        etag = generate_etag(data)
+    elif data is not None:
+        raise TypeError("both data and etag given")
+    if environ["REQUEST_METHOD"] not in ("GET", "HEAD"):
+        return False
+
+    unmodified = False
+    if isinstance(last_modified, string_types):
+        last_modified = parse_date(last_modified)
+
+    # ensure that microsecond is zero because the HTTP spec does not transmit
+    # that either and we might have some false positives.  See issue #39
+    if last_modified is not None:
+        last_modified = last_modified.replace(microsecond=0)
+
+    if_range = None
+    if not ignore_if_range and "HTTP_RANGE" in environ:
+        # https://tools.ietf.org/html/rfc7233#section-3.2
+        # A server MUST ignore an If-Range header field received in a request
+        # that does not contain a Range header field.
+        if_range = parse_if_range_header(environ.get("HTTP_IF_RANGE"))
+
+    if if_range is not None and if_range.date is not None:
+        modified_since = if_range.date
+    else:
+        modified_since = parse_date(environ.get("HTTP_IF_MODIFIED_SINCE"))
+
+    if modified_since and last_modified and last_modified <= modified_since:
+        unmodified = True
+
+    if etag:
+        etag, _ = unquote_etag(etag)
+        if if_range is not None and if_range.etag is not None:
+            unmodified = parse_etags(if_range.etag).contains(etag)
+        else:
+            if_none_match = parse_etags(environ.get("HTTP_IF_NONE_MATCH"))
+            if if_none_match:
+                # https://tools.ietf.org/html/rfc7232#section-3.2
+                # "A recipient MUST use the weak comparison function when comparing
+                # entity-tags for If-None-Match"
+                unmodified = if_none_match.contains_weak(etag)
+
+            # https://tools.ietf.org/html/rfc7232#section-3.1
+            # "Origin server MUST use the strong comparison function when
+            # comparing entity-tags for If-Match"
+            if_match = parse_etags(environ.get("HTTP_IF_MATCH"))
+            if if_match:
+                unmodified = not if_match.is_strong(etag)
+
+    return not unmodified
+
+
+def remove_entity_headers(headers, allowed=("expires", "content-location")):
+    """Remove all entity headers from a list or :class:`Headers` object.  This
+    operation works in-place.  `Expires` and `Content-Location` headers are
+    by default not removed.  The reason for this is :rfc:`2616` section
+    10.3.5 which specifies some entity headers that should be sent.
+
+    .. versionchanged:: 0.5
+       added `allowed` parameter.
+
+    :param headers: a list or :class:`Headers` object.
+    :param allowed: a list of headers that should still be allowed even though
+                    they are entity headers.
+    """
+    allowed = set(x.lower() for x in allowed)
+    headers[:] = [
+        (key, value)
+        for key, value in headers
+        if not is_entity_header(key) or key.lower() in allowed
+    ]
+
+
+def remove_hop_by_hop_headers(headers):
+    """Remove all HTTP/1.1 "Hop-by-Hop" headers from a list or
+    :class:`Headers` object.  This operation works in-place.
+
+    .. versionadded:: 0.5
+
+    :param headers: a list or :class:`Headers` object.
+    """
+    headers[:] = [
+        (key, value) for key, value in headers if not is_hop_by_hop_header(key)
+    ]
+
+
+def is_entity_header(header):
+    """Check if a header is an entity header.
+
+    .. versionadded:: 0.5
+
+    :param header: the header to test.
+    :return: `True` if it's an entity header, `False` otherwise.
+    """
+    return header.lower() in _entity_headers
+
+
+def is_hop_by_hop_header(header):
+    """Check if a header is an HTTP/1.1 "Hop-by-Hop" header.
+
+    .. versionadded:: 0.5
+
+    :param header: the header to test.
+    :return: `True` if it's an HTTP/1.1 "Hop-by-Hop" header, `False` otherwise.
+    """
+    return header.lower() in _hop_by_hop_headers
+
+
+def parse_cookie(header, charset="utf-8", errors="replace", cls=None):
+    """Parse a cookie.  Either from a string or WSGI environ.
+
+    Per default encoding errors are ignored.  If you want a different behavior
+    you can set `errors` to ``'replace'`` or ``'strict'``.  In strict mode a
+    :exc:`HTTPUnicodeError` is raised.
+
+    .. versionchanged:: 0.5
+       This function now returns a :class:`TypeConversionDict` instead of a
+       regular dict.  The `cls` parameter was added.
+
+    :param header: the header to be used to parse the cookie.  Alternatively
+                   this can be a WSGI environment.
+    :param charset: the charset for the cookie values.
+    :param errors: the error behavior for the charset decoding.
+    :param cls: an optional dict class to use.  If this is not specified
+                       or `None` the default :class:`TypeConversionDict` is
+                       used.
+    """
+    if isinstance(header, dict):
+        header = header.get("HTTP_COOKIE", "")
+    elif header is None:
+        header = ""
+
+    # If the value is an unicode string it's mangled through latin1.  This
+    # is done because on PEP 3333 on Python 3 all headers are assumed latin1
+    # which however is incorrect for cookies, which are sent in page encoding.
+    # As a result we
+    if isinstance(header, text_type):
+        header = header.encode("latin1", "replace")
+
+    if cls is None:
+        cls = TypeConversionDict
+
+    def _parse_pairs():
+        for key, val in _cookie_parse_impl(header):
+            key = to_unicode(key, charset, errors, allow_none_charset=True)
+            if not key:
+                continue
+            val = to_unicode(val, charset, errors, allow_none_charset=True)
+            yield try_coerce_native(key), val
+
+    return cls(_parse_pairs())
+
+
+def dump_cookie(
+    key,
+    value="",
+    max_age=None,
+    expires=None,
+    path="/",
+    domain=None,
+    secure=False,
+    httponly=False,
+    charset="utf-8",
+    sync_expires=True,
+    max_size=4093,
+    samesite=None,
+):
+    """Creates a new Set-Cookie header without the ``Set-Cookie`` prefix
+    The parameters are the same as in the cookie Morsel object in the
+    Python standard library but it accepts unicode data, too.
+
+    On Python 3 the return value of this function will be a unicode
+    string, on Python 2 it will be a native string.  In both cases the
+    return value is usually restricted to ascii as the vast majority of
+    values are properly escaped, but that is no guarantee.  If a unicode
+    string is returned it's tunneled through latin1 as required by
+    PEP 3333.
+
+    The return value is not ASCII safe if the key contains unicode
+    characters.  This is technically against the specification but
+    happens in the wild.  It's strongly recommended to not use
+    non-ASCII values for the keys.
+
+    :param max_age: should be a number of seconds, or `None` (default) if
+                    the cookie should last only as long as the client's
+                    browser session.  Additionally `timedelta` objects
+                    are accepted, too.
+    :param expires: should be a `datetime` object or unix timestamp.
+    :param path: limits the cookie to a given path, per default it will
+                 span the whole domain.
+    :param domain: Use this if you want to set a cross-domain cookie. For
+                   example, ``domain=".example.com"`` will set a cookie
+                   that is readable by the domain ``www.example.com``,
+                   ``foo.example.com`` etc. Otherwise, a cookie will only
+                   be readable by the domain that set it.
+    :param secure: The cookie will only be available via HTTPS
+    :param httponly: disallow JavaScript to access the cookie.  This is an
+                     extension to the cookie standard and probably not
+                     supported by all browsers.
+    :param charset: the encoding for unicode values.
+    :param sync_expires: automatically set expires if max_age is defined
+                         but expires not.
+    :param max_size: Warn if the final header value exceeds this size. The
+        default, 4093, should be safely `supported by most browsers
+        <cookie_>`_. Set to 0 to disable this check.
+    :param samesite: Limits the scope of the cookie such that it will only
+                     be attached to requests if those requests are "same-site".
+
+    .. _`cookie`: http://browsercookielimits.squawky.net/
+    """
+    key = to_bytes(key, charset)
+    value = to_bytes(value, charset)
+
+    if path is not None:
+        path = iri_to_uri(path, charset)
+    domain = _make_cookie_domain(domain)
+    if isinstance(max_age, timedelta):
+        max_age = (max_age.days * 60 * 60 * 24) + max_age.seconds
+    if expires is not None:
+        if not isinstance(expires, string_types):
+            expires = cookie_date(expires)
+    elif max_age is not None and sync_expires:
+        expires = to_bytes(cookie_date(time() + max_age))
+
+    samesite = samesite.title() if samesite else None
+    if samesite not in ("Strict", "Lax", None):
+        raise ValueError("invalid SameSite value; must be 'Strict', 'Lax' or None")
+
+    buf = [key + b"=" + _cookie_quote(value)]
+
+    # XXX: In theory all of these parameters that are not marked with `None`
+    # should be quoted.  Because stdlib did not quote it before I did not
+    # want to introduce quoting there now.
+    for k, v, q in (
+        (b"Domain", domain, True),
+        (b"Expires", expires, False),
+        (b"Max-Age", max_age, False),
+        (b"Secure", secure, None),
+        (b"HttpOnly", httponly, None),
+        (b"Path", path, False),
+        (b"SameSite", samesite, False),
+    ):
+        if q is None:
+            if v:
+                buf.append(k)
+            continue
+
+        if v is None:
+            continue
+
+        tmp = bytearray(k)
+        if not isinstance(v, (bytes, bytearray)):
+            v = to_bytes(text_type(v), charset)
+        if q:
+            v = _cookie_quote(v)
+        tmp += b"=" + v
+        buf.append(bytes(tmp))
+
+    # The return value will be an incorrectly encoded latin1 header on
+    # Python 3 for consistency with the headers object and a bytestring
+    # on Python 2 because that's how the API makes more sense.
+    rv = b"; ".join(buf)
+    if not PY2:
+        rv = rv.decode("latin1")
+
+    # Warn if the final value of the cookie is less than the limit. If the
+    # cookie is too large, then it may be silently ignored, which can be quite
+    # hard to debug.
+    cookie_size = len(rv)
+
+    if max_size and cookie_size > max_size:
+        value_size = len(value)
+        warnings.warn(
+            'The "{key}" cookie is too large: the value was {value_size} bytes'
+            " but the header required {extra_size} extra bytes. The final size"
+            " was {cookie_size} bytes but the limit is {max_size} bytes."
+            " Browsers may silently ignore cookies larger than this.".format(
+                key=key,
+                value_size=value_size,
+                extra_size=cookie_size - value_size,
+                cookie_size=cookie_size,
+                max_size=max_size,
+            ),
+            stacklevel=2,
+        )
+
+    return rv
+
+
+def is_byte_range_valid(start, stop, length):
+    """Checks if a given byte content range is valid for the given length.
+
+    .. versionadded:: 0.7
+    """
+    if (start is None) != (stop is None):
+        return False
+    elif start is None:
+        return length is None or length >= 0
+    elif length is None:
+        return 0 <= start < stop
+    elif start >= stop:
+        return False
+    return 0 <= start < length
+
+
+# circular dependency fun
+from .datastructures import Accept
+from .datastructures import Authorization
+from .datastructures import ContentRange
+from .datastructures import ETags
+from .datastructures import HeaderSet
+from .datastructures import IfRange
+from .datastructures import Range
+from .datastructures import RequestCacheControl
+from .datastructures import TypeConversionDict
+from .datastructures import WWWAuthenticate
+from .urls import iri_to_uri
+
+# DEPRECATED
+from .datastructures import CharsetAccept as _CharsetAccept
+from .datastructures import Headers as _Headers
+from .datastructures import LanguageAccept as _LanguageAccept
+from .datastructures import MIMEAccept as _MIMEAccept
+
+
+class MIMEAccept(_MIMEAccept):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.http.MIMEAccept' has moved to 'werkzeug"
+            ".datastructures.MIMEAccept' as of version 0.5. This old"
+            " import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(MIMEAccept, self).__init__(*args, **kwargs)
+
+
+class CharsetAccept(_CharsetAccept):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.http.CharsetAccept' has moved to 'werkzeug"
+            ".datastructures.CharsetAccept' as of version 0.5. This old"
+            " import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(CharsetAccept, self).__init__(*args, **kwargs)
+
+
+class LanguageAccept(_LanguageAccept):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.http.LanguageAccept' has moved to 'werkzeug"
+            ".datastructures.LanguageAccept' as of version 0.5. This"
+            " old import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(LanguageAccept, self).__init__(*args, **kwargs)
+
+
+class Headers(_Headers):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.http.Headers' has moved to 'werkzeug"
+            ".datastructures.Headers' as of version 0.5. This old"
+            " import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(Headers, self).__init__(*args, **kwargs)
diff --git a/python/werkzeug/local.py b/python/werkzeug/local.py
new file mode 100644
index 0000000..9a6088c
--- /dev/null
+++ b/python/werkzeug/local.py
@@ -0,0 +1,421 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.local
+    ~~~~~~~~~~~~~~
+
+    This module implements context-local objects.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import copy
+from functools import update_wrapper
+
+from ._compat import implements_bool
+from ._compat import PY2
+from .wsgi import ClosingIterator
+
+# since each thread has its own greenlet we can just use those as identifiers
+# for the context.  If greenlets are not available we fall back to the
+# current thread ident depending on where it is.
+try:
+    from greenlet import getcurrent as get_ident
+except ImportError:
+    try:
+        from thread import get_ident
+    except ImportError:
+        from _thread import get_ident
+
+
+def release_local(local):
+    """Releases the contents of the local for the current context.
+    This makes it possible to use locals without a manager.
+
+    Example::
+
+        >>> loc = Local()
+        >>> loc.foo = 42
+        >>> release_local(loc)
+        >>> hasattr(loc, 'foo')
+        False
+
+    With this function one can release :class:`Local` objects as well
+    as :class:`LocalStack` objects.  However it is not possible to
+    release data held by proxies that way, one always has to retain
+    a reference to the underlying local object in order to be able
+    to release it.
+
+    .. versionadded:: 0.6.1
+    """
+    local.__release_local__()
+
+
+class Local(object):
+    __slots__ = ("__storage__", "__ident_func__")
+
+    def __init__(self):
+        object.__setattr__(self, "__storage__", {})
+        object.__setattr__(self, "__ident_func__", get_ident)
+
+    def __iter__(self):
+        return iter(self.__storage__.items())
+
+    def __call__(self, proxy):
+        """Create a proxy for a name."""
+        return LocalProxy(self, proxy)
+
+    def __release_local__(self):
+        self.__storage__.pop(self.__ident_func__(), None)
+
+    def __getattr__(self, name):
+        try:
+            return self.__storage__[self.__ident_func__()][name]
+        except KeyError:
+            raise AttributeError(name)
+
+    def __setattr__(self, name, value):
+        ident = self.__ident_func__()
+        storage = self.__storage__
+        try:
+            storage[ident][name] = value
+        except KeyError:
+            storage[ident] = {name: value}
+
+    def __delattr__(self, name):
+        try:
+            del self.__storage__[self.__ident_func__()][name]
+        except KeyError:
+            raise AttributeError(name)
+
+
+class LocalStack(object):
+    """This class works similar to a :class:`Local` but keeps a stack
+    of objects instead.  This is best explained with an example::
+
+        >>> ls = LocalStack()
+        >>> ls.push(42)
+        >>> ls.top
+        42
+        >>> ls.push(23)
+        >>> ls.top
+        23
+        >>> ls.pop()
+        23
+        >>> ls.top
+        42
+
+    They can be force released by using a :class:`LocalManager` or with
+    the :func:`release_local` function but the correct way is to pop the
+    item from the stack after using.  When the stack is empty it will
+    no longer be bound to the current context (and as such released).
+
+    By calling the stack without arguments it returns a proxy that resolves to
+    the topmost item on the stack.
+
+    .. versionadded:: 0.6.1
+    """
+
+    def __init__(self):
+        self._local = Local()
+
+    def __release_local__(self):
+        self._local.__release_local__()
+
+    def _get__ident_func__(self):
+        return self._local.__ident_func__
+
+    def _set__ident_func__(self, value):
+        object.__setattr__(self._local, "__ident_func__", value)
+
+    __ident_func__ = property(_get__ident_func__, _set__ident_func__)
+    del _get__ident_func__, _set__ident_func__
+
+    def __call__(self):
+        def _lookup():
+            rv = self.top
+            if rv is None:
+                raise RuntimeError("object unbound")
+            return rv
+
+        return LocalProxy(_lookup)
+
+    def push(self, obj):
+        """Pushes a new item to the stack"""
+        rv = getattr(self._local, "stack", None)
+        if rv is None:
+            self._local.stack = rv = []
+        rv.append(obj)
+        return rv
+
+    def pop(self):
+        """Removes the topmost item from the stack, will return the
+        old value or `None` if the stack was already empty.
+        """
+        stack = getattr(self._local, "stack", None)
+        if stack is None:
+            return None
+        elif len(stack) == 1:
+            release_local(self._local)
+            return stack[-1]
+        else:
+            return stack.pop()
+
+    @property
+    def top(self):
+        """The topmost item on the stack.  If the stack is empty,
+        `None` is returned.
+        """
+        try:
+            return self._local.stack[-1]
+        except (AttributeError, IndexError):
+            return None
+
+
+class LocalManager(object):
+    """Local objects cannot manage themselves. For that you need a local
+    manager.  You can pass a local manager multiple locals or add them later
+    by appending them to `manager.locals`.  Every time the manager cleans up,
+    it will clean up all the data left in the locals for this context.
+
+    The `ident_func` parameter can be added to override the default ident
+    function for the wrapped locals.
+
+    .. versionchanged:: 0.6.1
+       Instead of a manager the :func:`release_local` function can be used
+       as well.
+
+    .. versionchanged:: 0.7
+       `ident_func` was added.
+    """
+
+    def __init__(self, locals=None, ident_func=None):
+        if locals is None:
+            self.locals = []
+        elif isinstance(locals, Local):
+            self.locals = [locals]
+        else:
+            self.locals = list(locals)
+        if ident_func is not None:
+            self.ident_func = ident_func
+            for local in self.locals:
+                object.__setattr__(local, "__ident_func__", ident_func)
+        else:
+            self.ident_func = get_ident
+
+    def get_ident(self):
+        """Return the context identifier the local objects use internally for
+        this context.  You cannot override this method to change the behavior
+        but use it to link other context local objects (such as SQLAlchemy's
+        scoped sessions) to the Werkzeug locals.
+
+        .. versionchanged:: 0.7
+           You can pass a different ident function to the local manager that
+           will then be propagated to all the locals passed to the
+           constructor.
+        """
+        return self.ident_func()
+
+    def cleanup(self):
+        """Manually clean up the data in the locals for this context.  Call
+        this at the end of the request or use `make_middleware()`.
+        """
+        for local in self.locals:
+            release_local(local)
+
+    def make_middleware(self, app):
+        """Wrap a WSGI application so that cleaning up happens after
+        request end.
+        """
+
+        def application(environ, start_response):
+            return ClosingIterator(app(environ, start_response), self.cleanup)
+
+        return application
+
+    def middleware(self, func):
+        """Like `make_middleware` but for decorating functions.
+
+        Example usage::
+
+            @manager.middleware
+            def application(environ, start_response):
+                ...
+
+        The difference to `make_middleware` is that the function passed
+        will have all the arguments copied from the inner application
+        (name, docstring, module).
+        """
+        return update_wrapper(self.make_middleware(func), func)
+
+    def __repr__(self):
+        return "<%s storages: %d>" % (self.__class__.__name__, len(self.locals))
+
+
+@implements_bool
+class LocalProxy(object):
+    """Acts as a proxy for a werkzeug local.  Forwards all operations to
+    a proxied object.  The only operations not supported for forwarding
+    are right handed operands and any kind of assignment.
+
+    Example usage::
+
+        from werkzeug.local import Local
+        l = Local()
+
+        # these are proxies
+        request = l('request')
+        user = l('user')
+
+
+        from werkzeug.local import LocalStack
+        _response_local = LocalStack()
+
+        # this is a proxy
+        response = _response_local()
+
+    Whenever something is bound to l.user / l.request the proxy objects
+    will forward all operations.  If no object is bound a :exc:`RuntimeError`
+    will be raised.
+
+    To create proxies to :class:`Local` or :class:`LocalStack` objects,
+    call the object as shown above.  If you want to have a proxy to an
+    object looked up by a function, you can (as of Werkzeug 0.6.1) pass
+    a function to the :class:`LocalProxy` constructor::
+
+        session = LocalProxy(lambda: get_current_request().session)
+
+    .. versionchanged:: 0.6.1
+       The class can be instantiated with a callable as well now.
+    """
+
+    __slots__ = ("__local", "__dict__", "__name__", "__wrapped__")
+
+    def __init__(self, local, name=None):
+        object.__setattr__(self, "_LocalProxy__local", local)
+        object.__setattr__(self, "__name__", name)
+        if callable(local) and not hasattr(local, "__release_local__"):
+            # "local" is a callable that is not an instance of Local or
+            # LocalManager: mark it as a wrapped function.
+            object.__setattr__(self, "__wrapped__", local)
+
+    def _get_current_object(self):
+        """Return the current object.  This is useful if you want the real
+        object behind the proxy at a time for performance reasons or because
+        you want to pass the object into a different context.
+        """
+        if not hasattr(self.__local, "__release_local__"):
+            return self.__local()
+        try:
+            return getattr(self.__local, self.__name__)
+        except AttributeError:
+            raise RuntimeError("no object bound to %s" % self.__name__)
+
+    @property
+    def __dict__(self):
+        try:
+            return self._get_current_object().__dict__
+        except RuntimeError:
+            raise AttributeError("__dict__")
+
+    def __repr__(self):
+        try:
+            obj = self._get_current_object()
+        except RuntimeError:
+            return "<%s unbound>" % self.__class__.__name__
+        return repr(obj)
+
+    def __bool__(self):
+        try:
+            return bool(self._get_current_object())
+        except RuntimeError:
+            return False
+
+    def __unicode__(self):
+        try:
+            return unicode(self._get_current_object())  # noqa
+        except RuntimeError:
+            return repr(self)
+
+    def __dir__(self):
+        try:
+            return dir(self._get_current_object())
+        except RuntimeError:
+            return []
+
+    def __getattr__(self, name):
+        if name == "__members__":
+            return dir(self._get_current_object())
+        return getattr(self._get_current_object(), name)
+
+    def __setitem__(self, key, value):
+        self._get_current_object()[key] = value
+
+    def __delitem__(self, key):
+        del self._get_current_object()[key]
+
+    if PY2:
+        __getslice__ = lambda x, i, j: x._get_current_object()[i:j]
+
+        def __setslice__(self, i, j, seq):
+            self._get_current_object()[i:j] = seq
+
+        def __delslice__(self, i, j):
+            del self._get_current_object()[i:j]
+
+    __setattr__ = lambda x, n, v: setattr(x._get_current_object(), n, v)
+    __delattr__ = lambda x, n: delattr(x._get_current_object(), n)
+    __str__ = lambda x: str(x._get_current_object())
+    __lt__ = lambda x, o: x._get_current_object() < o
+    __le__ = lambda x, o: x._get_current_object() <= o
+    __eq__ = lambda x, o: x._get_current_object() == o
+    __ne__ = lambda x, o: x._get_current_object() != o
+    __gt__ = lambda x, o: x._get_current_object() > o
+    __ge__ = lambda x, o: x._get_current_object() >= o
+    __cmp__ = lambda x, o: cmp(x._get_current_object(), o)  # noqa
+    __hash__ = lambda x: hash(x._get_current_object())
+    __call__ = lambda x, *a, **kw: x._get_current_object()(*a, **kw)
+    __len__ = lambda x: len(x._get_current_object())
+    __getitem__ = lambda x, i: x._get_current_object()[i]
+    __iter__ = lambda x: iter(x._get_current_object())
+    __contains__ = lambda x, i: i in x._get_current_object()
+    __add__ = lambda x, o: x._get_current_object() + o
+    __sub__ = lambda x, o: x._get_current_object() - o
+    __mul__ = lambda x, o: x._get_current_object() * o
+    __floordiv__ = lambda x, o: x._get_current_object() // o
+    __mod__ = lambda x, o: x._get_current_object() % o
+    __divmod__ = lambda x, o: x._get_current_object().__divmod__(o)
+    __pow__ = lambda x, o: x._get_current_object() ** o
+    __lshift__ = lambda x, o: x._get_current_object() << o
+    __rshift__ = lambda x, o: x._get_current_object() >> o
+    __and__ = lambda x, o: x._get_current_object() & o
+    __xor__ = lambda x, o: x._get_current_object() ^ o
+    __or__ = lambda x, o: x._get_current_object() | o
+    __div__ = lambda x, o: x._get_current_object().__div__(o)
+    __truediv__ = lambda x, o: x._get_current_object().__truediv__(o)
+    __neg__ = lambda x: -(x._get_current_object())
+    __pos__ = lambda x: +(x._get_current_object())
+    __abs__ = lambda x: abs(x._get_current_object())
+    __invert__ = lambda x: ~(x._get_current_object())
+    __complex__ = lambda x: complex(x._get_current_object())
+    __int__ = lambda x: int(x._get_current_object())
+    __long__ = lambda x: long(x._get_current_object())  # noqa
+    __float__ = lambda x: float(x._get_current_object())
+    __oct__ = lambda x: oct(x._get_current_object())
+    __hex__ = lambda x: hex(x._get_current_object())
+    __index__ = lambda x: x._get_current_object().__index__()
+    __coerce__ = lambda x, o: x._get_current_object().__coerce__(x, o)
+    __enter__ = lambda x: x._get_current_object().__enter__()
+    __exit__ = lambda x, *a, **kw: x._get_current_object().__exit__(*a, **kw)
+    __radd__ = lambda x, o: o + x._get_current_object()
+    __rsub__ = lambda x, o: o - x._get_current_object()
+    __rmul__ = lambda x, o: o * x._get_current_object()
+    __rdiv__ = lambda x, o: o / x._get_current_object()
+    if PY2:
+        __rtruediv__ = lambda x, o: x._get_current_object().__rtruediv__(o)
+    else:
+        __rtruediv__ = __rdiv__
+    __rfloordiv__ = lambda x, o: o // x._get_current_object()
+    __rmod__ = lambda x, o: o % x._get_current_object()
+    __rdivmod__ = lambda x, o: x._get_current_object().__rdivmod__(o)
+    __copy__ = lambda x: copy.copy(x._get_current_object())
+    __deepcopy__ = lambda x, memo: copy.deepcopy(x._get_current_object(), memo)
diff --git a/python/werkzeug/middleware/__init__.py b/python/werkzeug/middleware/__init__.py
new file mode 100644
index 0000000..5e049f5
--- /dev/null
+++ b/python/werkzeug/middleware/__init__.py
@@ -0,0 +1,25 @@
+"""
+Middleware
+==========
+
+A WSGI middleware is a WSGI application that wraps another application
+in order to observe or change its behavior. Werkzeug provides some
+middleware for common use cases.
+
+.. toctree::
+    :maxdepth: 1
+
+    proxy_fix
+    shared_data
+    dispatcher
+    http_proxy
+    lint
+    profiler
+
+The :doc:`interactive debugger </debug>` is also a middleware that can
+be applied manually, although it is typically used automatically with
+the :doc:`development server </serving>`.
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
diff --git a/python/werkzeug/middleware/dispatcher.py b/python/werkzeug/middleware/dispatcher.py
new file mode 100644
index 0000000..2eb173e
--- /dev/null
+++ b/python/werkzeug/middleware/dispatcher.py
@@ -0,0 +1,66 @@
+"""
+Application Dispatcher
+======================
+
+This middleware creates a single WSGI application that dispatches to
+multiple other WSGI applications mounted at different URL paths.
+
+A common example is writing a Single Page Application, where you have a
+backend API and a frontend written in JavaScript that does the routing
+in the browser rather than requesting different pages from the server.
+The frontend is a single HTML and JS file that should be served for any
+path besides "/api".
+
+This example dispatches to an API app under "/api", an admin app
+under "/admin", and an app that serves frontend files for all other
+requests::
+
+    app = DispatcherMiddleware(serve_frontend, {
+        '/api': api_app,
+        '/admin': admin_app,
+    })
+
+In production, you might instead handle this at the HTTP server level,
+serving files or proxying to application servers based on location. The
+API and admin apps would each be deployed with a separate WSGI server,
+and the static files would be served directly by the HTTP server.
+
+.. autoclass:: DispatcherMiddleware
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+
+
+class DispatcherMiddleware(object):
+    """Combine multiple applications as a single WSGI application.
+    Requests are dispatched to an application based on the path it is
+    mounted under.
+
+    :param app: The WSGI application to dispatch to if the request
+        doesn't match a mounted path.
+    :param mounts: Maps path prefixes to applications for dispatching.
+    """
+
+    def __init__(self, app, mounts=None):
+        self.app = app
+        self.mounts = mounts or {}
+
+    def __call__(self, environ, start_response):
+        script = environ.get("PATH_INFO", "")
+        path_info = ""
+
+        while "/" in script:
+            if script in self.mounts:
+                app = self.mounts[script]
+                break
+
+            script, last_item = script.rsplit("/", 1)
+            path_info = "/%s%s" % (last_item, path_info)
+        else:
+            app = self.mounts.get(script, self.app)
+
+        original_script_name = environ.get("SCRIPT_NAME", "")
+        environ["SCRIPT_NAME"] = original_script_name + script
+        environ["PATH_INFO"] = path_info
+        return app(environ, start_response)
diff --git a/python/werkzeug/middleware/http_proxy.py b/python/werkzeug/middleware/http_proxy.py
new file mode 100644
index 0000000..bfdc071
--- /dev/null
+++ b/python/werkzeug/middleware/http_proxy.py
@@ -0,0 +1,219 @@
+"""
+Basic HTTP Proxy
+================
+
+.. autoclass:: ProxyMiddleware
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+import socket
+
+from ..datastructures import EnvironHeaders
+from ..http import is_hop_by_hop_header
+from ..urls import url_parse
+from ..urls import url_quote
+from ..wsgi import get_input_stream
+
+try:
+    from http import client
+except ImportError:
+    import httplib as client
+
+
+class ProxyMiddleware(object):
+    """Proxy requests under a path to an external server, routing other
+    requests to the app.
+
+    This middleware can only proxy HTTP requests, as that is the only
+    protocol handled by the WSGI server. Other protocols, such as
+    websocket requests, cannot be proxied at this layer. This should
+    only be used for development, in production a real proxying server
+    should be used.
+
+    The middleware takes a dict that maps a path prefix to a dict
+    describing the host to be proxied to::
+
+        app = ProxyMiddleware(app, {
+            "/static/": {
+                "target": "http://127.0.0.1:5001/",
+            }
+        })
+
+    Each host has the following options:
+
+    ``target``:
+        The target URL to dispatch to. This is required.
+    ``remove_prefix``:
+        Whether to remove the prefix from the URL before dispatching it
+        to the target. The default is ``False``.
+    ``host``:
+        ``"<auto>"`` (default):
+            The host header is automatically rewritten to the URL of the
+            target.
+        ``None``:
+            The host header is unmodified from the client request.
+        Any other value:
+            The host header is overwritten with the value.
+    ``headers``:
+        A dictionary of headers to be sent with the request to the
+        target. The default is ``{}``.
+    ``ssl_context``:
+        A :class:`ssl.SSLContext` defining how to verify requests if the
+        target is HTTPS. The default is ``None``.
+
+    In the example above, everything under ``"/static/"`` is proxied to
+    the server on port 5001. The host header is rewritten to the target,
+    and the ``"/static/"`` prefix is removed from the URLs.
+
+    :param app: The WSGI application to wrap.
+    :param targets: Proxy target configurations. See description above.
+    :param chunk_size: Size of chunks to read from input stream and
+        write to target.
+    :param timeout: Seconds before an operation to a target fails.
+
+    .. versionadded:: 0.14
+    """
+
+    def __init__(self, app, targets, chunk_size=2 << 13, timeout=10):
+        def _set_defaults(opts):
+            opts.setdefault("remove_prefix", False)
+            opts.setdefault("host", "<auto>")
+            opts.setdefault("headers", {})
+            opts.setdefault("ssl_context", None)
+            return opts
+
+        self.app = app
+        self.targets = dict(
+            ("/%s/" % k.strip("/"), _set_defaults(v)) for k, v in targets.items()
+        )
+        self.chunk_size = chunk_size
+        self.timeout = timeout
+
+    def proxy_to(self, opts, path, prefix):
+        target = url_parse(opts["target"])
+
+        def application(environ, start_response):
+            headers = list(EnvironHeaders(environ).items())
+            headers[:] = [
+                (k, v)
+                for k, v in headers
+                if not is_hop_by_hop_header(k)
+                and k.lower() not in ("content-length", "host")
+            ]
+            headers.append(("Connection", "close"))
+
+            if opts["host"] == "<auto>":
+                headers.append(("Host", target.ascii_host))
+            elif opts["host"] is None:
+                headers.append(("Host", environ["HTTP_HOST"]))
+            else:
+                headers.append(("Host", opts["host"]))
+
+            headers.extend(opts["headers"].items())
+            remote_path = path
+
+            if opts["remove_prefix"]:
+                remote_path = "%s/%s" % (
+                    target.path.rstrip("/"),
+                    remote_path[len(prefix) :].lstrip("/"),
+                )
+
+            content_length = environ.get("CONTENT_LENGTH")
+            chunked = False
+
+            if content_length not in ("", None):
+                headers.append(("Content-Length", content_length))
+            elif content_length is not None:
+                headers.append(("Transfer-Encoding", "chunked"))
+                chunked = True
+
+            try:
+                if target.scheme == "http":
+                    con = client.HTTPConnection(
+                        target.ascii_host, target.port or 80, timeout=self.timeout
+                    )
+                elif target.scheme == "https":
+                    con = client.HTTPSConnection(
+                        target.ascii_host,
+                        target.port or 443,
+                        timeout=self.timeout,
+                        context=opts["ssl_context"],
+                    )
+                else:
+                    raise RuntimeError(
+                        "Target scheme must be 'http' or 'https', got '{}'.".format(
+                            target.scheme
+                        )
+                    )
+
+                con.connect()
+                remote_url = url_quote(remote_path)
+                querystring = environ["QUERY_STRING"]
+
+                if querystring:
+                    remote_url = remote_url + "?" + querystring
+
+                con.putrequest(environ["REQUEST_METHOD"], remote_url, skip_host=True)
+
+                for k, v in headers:
+                    if k.lower() == "connection":
+                        v = "close"
+
+                    con.putheader(k, v)
+
+                con.endheaders()
+                stream = get_input_stream(environ)
+
+                while 1:
+                    data = stream.read(self.chunk_size)
+
+                    if not data:
+                        break
+
+                    if chunked:
+                        con.send(b"%x\r\n%s\r\n" % (len(data), data))
+                    else:
+                        con.send(data)
+
+                resp = con.getresponse()
+            except socket.error:
+                from ..exceptions import BadGateway
+
+                return BadGateway()(environ, start_response)
+
+            start_response(
+                "%d %s" % (resp.status, resp.reason),
+                [
+                    (k.title(), v)
+                    for k, v in resp.getheaders()
+                    if not is_hop_by_hop_header(k)
+                ],
+            )
+
+            def read():
+                while 1:
+                    try:
+                        data = resp.read(self.chunk_size)
+                    except socket.error:
+                        break
+
+                    if not data:
+                        break
+
+                    yield data
+
+            return read()
+
+        return application
+
+    def __call__(self, environ, start_response):
+        path = environ["PATH_INFO"]
+        app = self.app
+
+        for prefix, opts in self.targets.items():
+            if path.startswith(prefix):
+                app = self.proxy_to(opts, path, prefix)
+                break
+
+        return app(environ, start_response)
diff --git a/python/werkzeug/middleware/lint.py b/python/werkzeug/middleware/lint.py
new file mode 100644
index 0000000..98f9581
--- /dev/null
+++ b/python/werkzeug/middleware/lint.py
@@ -0,0 +1,408 @@
+"""
+WSGI Protocol Linter
+====================
+
+This module provides a middleware that performs sanity checks on the
+behavior of the WSGI server and application. It checks that the
+:pep:`3333` WSGI spec is properly implemented. It also warns on some
+common HTTP errors such as non-empty responses for 304 status codes.
+
+.. autoclass:: LintMiddleware
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+from warnings import warn
+
+from .._compat import implements_iterator
+from .._compat import PY2
+from .._compat import string_types
+from ..datastructures import Headers
+from ..http import is_entity_header
+from ..wsgi import FileWrapper
+
+try:
+    from urllib.parse import urlparse
+except ImportError:
+    from urlparse import urlparse
+
+
+class WSGIWarning(Warning):
+    """Warning class for WSGI warnings."""
+
+
+class HTTPWarning(Warning):
+    """Warning class for HTTP warnings."""
+
+
+def check_string(context, obj, stacklevel=3):
+    if type(obj) is not str:
+        warn(
+            "'%s' requires strings, got '%s'" % (context, type(obj).__name__),
+            WSGIWarning,
+        )
+
+
+class InputStream(object):
+    def __init__(self, stream):
+        self._stream = stream
+
+    def read(self, *args):
+        if len(args) == 0:
+            warn(
+                "WSGI does not guarantee an EOF marker on the input stream, thus making"
+                " calls to 'wsgi.input.read()' unsafe. Conforming servers may never"
+                " return from this call.",
+                WSGIWarning,
+                stacklevel=2,
+            )
+        elif len(args) != 1:
+            warn(
+                "Too many parameters passed to 'wsgi.input.read()'.",
+                WSGIWarning,
+                stacklevel=2,
+            )
+        return self._stream.read(*args)
+
+    def readline(self, *args):
+        if len(args) == 0:
+            warn(
+                "Calls to 'wsgi.input.readline()' without arguments are unsafe. Use"
+                " 'wsgi.input.read()' instead.",
+                WSGIWarning,
+                stacklevel=2,
+            )
+        elif len(args) == 1:
+            warn(
+                "'wsgi.input.readline()' was called with a size hint. WSGI does not"
+                " support this, although it's available on all major servers.",
+                WSGIWarning,
+                stacklevel=2,
+            )
+        else:
+            raise TypeError("Too many arguments passed to 'wsgi.input.readline()'.")
+        return self._stream.readline(*args)
+
+    def __iter__(self):
+        try:
+            return iter(self._stream)
+        except TypeError:
+            warn("'wsgi.input' is not iterable.", WSGIWarning, stacklevel=2)
+            return iter(())
+
+    def close(self):
+        warn("The application closed the input stream!", WSGIWarning, stacklevel=2)
+        self._stream.close()
+
+
+class ErrorStream(object):
+    def __init__(self, stream):
+        self._stream = stream
+
+    def write(self, s):
+        check_string("wsgi.error.write()", s)
+        self._stream.write(s)
+
+    def flush(self):
+        self._stream.flush()
+
+    def writelines(self, seq):
+        for line in seq:
+            self.write(line)
+
+    def close(self):
+        warn("The application closed the error stream!", WSGIWarning, stacklevel=2)
+        self._stream.close()
+
+
+class GuardedWrite(object):
+    def __init__(self, write, chunks):
+        self._write = write
+        self._chunks = chunks
+
+    def __call__(self, s):
+        check_string("write()", s)
+        self._write.write(s)
+        self._chunks.append(len(s))
+
+
+@implements_iterator
+class GuardedIterator(object):
+    def __init__(self, iterator, headers_set, chunks):
+        self._iterator = iterator
+        if PY2:
+            self._next = iter(iterator).next
+        else:
+            self._next = iter(iterator).__next__
+        self.closed = False
+        self.headers_set = headers_set
+        self.chunks = chunks
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.closed:
+            warn("Iterated over closed 'app_iter'.", WSGIWarning, stacklevel=2)
+
+        rv = self._next()
+
+        if not self.headers_set:
+            warn(
+                "The application returned before it started the response.",
+                WSGIWarning,
+                stacklevel=2,
+            )
+
+        check_string("application iterator items", rv)
+        self.chunks.append(len(rv))
+        return rv
+
+    def close(self):
+        self.closed = True
+
+        if hasattr(self._iterator, "close"):
+            self._iterator.close()
+
+        if self.headers_set:
+            status_code, headers = self.headers_set
+            bytes_sent = sum(self.chunks)
+            content_length = headers.get("content-length", type=int)
+
+            if status_code == 304:
+                for key, _value in headers:
+                    key = key.lower()
+                    if key not in ("expires", "content-location") and is_entity_header(
+                        key
+                    ):
+                        warn(
+                            "Entity header %r found in 304 response." % key, HTTPWarning
+                        )
+                if bytes_sent:
+                    warn("304 responses must not have a body.", HTTPWarning)
+            elif 100 <= status_code < 200 or status_code == 204:
+                if content_length != 0:
+                    warn(
+                        "%r responses must have an empty content length." % status_code,
+                        HTTPWarning,
+                    )
+                if bytes_sent:
+                    warn(
+                        "%r responses must not have a body." % status_code, HTTPWarning
+                    )
+            elif content_length is not None and content_length != bytes_sent:
+                warn(
+                    "Content-Length and the number of bytes sent to the client do not"
+                    " match.",
+                    WSGIWarning,
+                )
+
+    def __del__(self):
+        if not self.closed:
+            try:
+                warn(
+                    "Iterator was garbage collected before it was closed.", WSGIWarning
+                )
+            except Exception:
+                pass
+
+
+class LintMiddleware(object):
+    """Warns about common errors in the WSGI and HTTP behavior of the
+    server and wrapped application. Some of the issues it check are:
+
+    -   invalid status codes
+    -   non-bytestrings sent to the WSGI server
+    -   strings returned from the WSGI application
+    -   non-empty conditional responses
+    -   unquoted etags
+    -   relative URLs in the Location header
+    -   unsafe calls to wsgi.input
+    -   unclosed iterators
+
+    Error information is emitted using the :mod:`warnings` module.
+
+    :param app: The WSGI application to wrap.
+
+    .. code-block:: python
+
+        from werkzeug.middleware.lint import LintMiddleware
+        app = LintMiddleware(app)
+    """
+
+    def __init__(self, app):
+        self.app = app
+
+    def check_environ(self, environ):
+        if type(environ) is not dict:
+            warn(
+                "WSGI environment is not a standard Python dict.",
+                WSGIWarning,
+                stacklevel=4,
+            )
+        for key in (
+            "REQUEST_METHOD",
+            "SERVER_NAME",
+            "SERVER_PORT",
+            "wsgi.version",
+            "wsgi.input",
+            "wsgi.errors",
+            "wsgi.multithread",
+            "wsgi.multiprocess",
+            "wsgi.run_once",
+        ):
+            if key not in environ:
+                warn(
+                    "Required environment key %r not found" % key,
+                    WSGIWarning,
+                    stacklevel=3,
+                )
+        if environ["wsgi.version"] != (1, 0):
+            warn("Environ is not a WSGI 1.0 environ.", WSGIWarning, stacklevel=3)
+
+        script_name = environ.get("SCRIPT_NAME", "")
+        path_info = environ.get("PATH_INFO", "")
+
+        if script_name and script_name[0] != "/":
+            warn(
+                "'SCRIPT_NAME' does not start with a slash: %r" % script_name,
+                WSGIWarning,
+                stacklevel=3,
+            )
+
+        if path_info and path_info[0] != "/":
+            warn(
+                "'PATH_INFO' does not start with a slash: %r" % path_info,
+                WSGIWarning,
+                stacklevel=3,
+            )
+
+    def check_start_response(self, status, headers, exc_info):
+        check_string("status", status)
+        status_code = status.split(None, 1)[0]
+
+        if len(status_code) != 3 or not status_code.isdigit():
+            warn(WSGIWarning("Status code must be three digits"), stacklevel=3)
+
+        if len(status) < 4 or status[3] != " ":
+            warn(
+                WSGIWarning(
+                    "Invalid value for status %r.  Valid "
+                    "status strings are three digits, a space "
+                    "and a status explanation"
+                ),
+                stacklevel=3,
+            )
+
+        status_code = int(status_code)
+
+        if status_code < 100:
+            warn(WSGIWarning("status code < 100 detected"), stacklevel=3)
+
+        if type(headers) is not list:
+            warn(WSGIWarning("header list is not a list"), stacklevel=3)
+
+        for item in headers:
+            if type(item) is not tuple or len(item) != 2:
+                warn(WSGIWarning("Headers must tuple 2-item tuples"), stacklevel=3)
+            name, value = item
+            if type(name) is not str or type(value) is not str:
+                warn(WSGIWarning("header items must be strings"), stacklevel=3)
+            if name.lower() == "status":
+                warn(
+                    WSGIWarning(
+                        "The status header is not supported due to "
+                        "conflicts with the CGI spec."
+                    ),
+                    stacklevel=3,
+                )
+
+        if exc_info is not None and not isinstance(exc_info, tuple):
+            warn(WSGIWarning("invalid value for exc_info"), stacklevel=3)
+
+        headers = Headers(headers)
+        self.check_headers(headers)
+
+        return status_code, headers
+
+    def check_headers(self, headers):
+        etag = headers.get("etag")
+
+        if etag is not None:
+            if etag.startswith(("W/", "w/")):
+                if etag.startswith("w/"):
+                    warn(
+                        HTTPWarning("weak etag indicator should be upcase."),
+                        stacklevel=4,
+                    )
+
+                etag = etag[2:]
+
+            if not (etag[:1] == etag[-1:] == '"'):
+                warn(HTTPWarning("unquoted etag emitted."), stacklevel=4)
+
+        location = headers.get("location")
+
+        if location is not None:
+            if not urlparse(location).netloc:
+                warn(
+                    HTTPWarning("absolute URLs required for location header"),
+                    stacklevel=4,
+                )
+
+    def check_iterator(self, app_iter):
+        if isinstance(app_iter, string_types):
+            warn(
+                "The application returned astring. The response will send one character"
+                " at a time to the client, which will kill performance. Return a list"
+                " or iterable instead.",
+                WSGIWarning,
+                stacklevel=3,
+            )
+
+    def __call__(self, *args, **kwargs):
+        if len(args) != 2:
+            warn("A WSGI app takes two arguments.", WSGIWarning, stacklevel=2)
+
+        if kwargs:
+            warn(
+                "A WSGI app does not take keyword arguments.", WSGIWarning, stacklevel=2
+            )
+
+        environ, start_response = args
+
+        self.check_environ(environ)
+        environ["wsgi.input"] = InputStream(environ["wsgi.input"])
+        environ["wsgi.errors"] = ErrorStream(environ["wsgi.errors"])
+
+        # Hook our own file wrapper in so that applications will always
+        # iterate to the end and we can check the content length.
+        environ["wsgi.file_wrapper"] = FileWrapper
+
+        headers_set = []
+        chunks = []
+
+        def checking_start_response(*args, **kwargs):
+            if len(args) not in (2, 3):
+                warn(
+                    "Invalid number of arguments: %s, expected 2 or 3." % len(args),
+                    WSGIWarning,
+                    stacklevel=2,
+                )
+
+            if kwargs:
+                warn("'start_response' does not take keyword arguments.", WSGIWarning)
+
+            status, headers = args[:2]
+
+            if len(args) == 3:
+                exc_info = args[2]
+            else:
+                exc_info = None
+
+            headers_set[:] = self.check_start_response(status, headers, exc_info)
+            return GuardedWrite(start_response(status, headers, exc_info), chunks)
+
+        app_iter = self.app(environ, checking_start_response)
+        self.check_iterator(app_iter)
+        return GuardedIterator(app_iter, headers_set, chunks)
diff --git a/python/werkzeug/middleware/profiler.py b/python/werkzeug/middleware/profiler.py
new file mode 100644
index 0000000..32a14d9
--- /dev/null
+++ b/python/werkzeug/middleware/profiler.py
@@ -0,0 +1,132 @@
+"""
+Application Profiler
+====================
+
+This module provides a middleware that profiles each request with the
+:mod:`cProfile` module. This can help identify bottlenecks in your code
+that may be slowing down your application.
+
+.. autoclass:: ProfilerMiddleware
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+from __future__ import print_function
+
+import os.path
+import sys
+import time
+from pstats import Stats
+
+try:
+    from cProfile import Profile
+except ImportError:
+    from profile import Profile
+
+
+class ProfilerMiddleware(object):
+    """Wrap a WSGI application and profile the execution of each
+    request. Responses are buffered so that timings are more exact.
+
+    If ``stream`` is given, :class:`pstats.Stats` are written to it
+    after each request. If ``profile_dir`` is given, :mod:`cProfile`
+    data files are saved to that directory, one file per request.
+
+    The filename can be customized by passing ``filename_format``. If
+    it is a string, it will be formatted using :meth:`str.format` with
+    the following fields available:
+
+    -   ``{method}`` - The request method; GET, POST, etc.
+    -   ``{path}`` - The request path or 'root' should one not exist.
+    -   ``{elapsed}`` - The elapsed time of the request.
+    -   ``{time}`` - The time of the request.
+
+    If it is a callable, it will be called with the WSGI ``environ``
+    dict and should return a filename.
+
+    :param app: The WSGI application to wrap.
+    :param stream: Write stats to this stream. Disable with ``None``.
+    :param sort_by: A tuple of columns to sort stats by. See
+        :meth:`pstats.Stats.sort_stats`.
+    :param restrictions: A tuple of restrictions to filter stats by. See
+        :meth:`pstats.Stats.print_stats`.
+    :param profile_dir: Save profile data files to this directory.
+    :param filename_format: Format string for profile data file names,
+        or a callable returning a name. See explanation above.
+
+    .. code-block:: python
+
+        from werkzeug.middleware.profiler import ProfilerMiddleware
+        app = ProfilerMiddleware(app)
+
+    .. versionchanged:: 0.15
+        Stats are written even if ``profile_dir`` is given, and can be
+        disable by passing ``stream=None``.
+
+    .. versionadded:: 0.15
+        Added ``filename_format``.
+
+    .. versionadded:: 0.9
+        Added ``restrictions`` and ``profile_dir``.
+    """
+
+    def __init__(
+        self,
+        app,
+        stream=sys.stdout,
+        sort_by=("time", "calls"),
+        restrictions=(),
+        profile_dir=None,
+        filename_format="{method}.{path}.{elapsed:.0f}ms.{time:.0f}.prof",
+    ):
+        self._app = app
+        self._stream = stream
+        self._sort_by = sort_by
+        self._restrictions = restrictions
+        self._profile_dir = profile_dir
+        self._filename_format = filename_format
+
+    def __call__(self, environ, start_response):
+        response_body = []
+
+        def catching_start_response(status, headers, exc_info=None):
+            start_response(status, headers, exc_info)
+            return response_body.append
+
+        def runapp():
+            app_iter = self._app(environ, catching_start_response)
+            response_body.extend(app_iter)
+
+            if hasattr(app_iter, "close"):
+                app_iter.close()
+
+        profile = Profile()
+        start = time.time()
+        profile.runcall(runapp)
+        body = b"".join(response_body)
+        elapsed = time.time() - start
+
+        if self._profile_dir is not None:
+            if callable(self._filename_format):
+                filename = self._filename_format(environ)
+            else:
+                filename = self._filename_format.format(
+                    method=environ["REQUEST_METHOD"],
+                    path=(
+                        environ.get("PATH_INFO").strip("/").replace("/", ".") or "root"
+                    ),
+                    elapsed=elapsed * 1000.0,
+                    time=time.time(),
+                )
+            filename = os.path.join(self._profile_dir, filename)
+            profile.dump_stats(filename)
+
+        if self._stream is not None:
+            stats = Stats(profile, stream=self._stream)
+            stats.sort_stats(*self._sort_by)
+            print("-" * 80, file=self._stream)
+            print("PATH: {!r}".format(environ.get("PATH_INFO", "")), file=self._stream)
+            stats.print_stats(*self._restrictions)
+            print("-" * 80 + "\n", file=self._stream)
+
+        return [body]
diff --git a/python/werkzeug/middleware/proxy_fix.py b/python/werkzeug/middleware/proxy_fix.py
new file mode 100644
index 0000000..dc1dacc
--- /dev/null
+++ b/python/werkzeug/middleware/proxy_fix.py
@@ -0,0 +1,228 @@
+"""
+X-Forwarded-For Proxy Fix
+=========================
+
+This module provides a middleware that adjusts the WSGI environ based on
+``X-Forwarded-`` headers that proxies in front of an application may
+set.
+
+When an application is running behind a proxy server, WSGI may see the
+request as coming from that server rather than the real client. Proxies
+set various headers to track where the request actually came from.
+
+This middleware should only be applied if the application is actually
+behind such a proxy, and should be configured with the number of proxies
+that are chained in front of it. Not all proxies set all the headers.
+Since incoming headers can be faked, you must set how many proxies are
+setting each header so the middleware knows what to trust.
+
+.. autoclass:: ProxyFix
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+import warnings
+
+
+class ProxyFix(object):
+    """Adjust the WSGI environ based on ``X-Forwarded-`` that proxies in
+    front of the application may set.
+
+    -   ``X-Forwarded-For`` sets ``REMOTE_ADDR``.
+    -   ``X-Forwarded-Proto`` sets ``wsgi.url_scheme``.
+    -   ``X-Forwarded-Host`` sets ``HTTP_HOST``, ``SERVER_NAME``, and
+        ``SERVER_PORT``.
+    -   ``X-Forwarded-Port`` sets ``HTTP_HOST`` and ``SERVER_PORT``.
+    -   ``X-Forwarded-Prefix`` sets ``SCRIPT_NAME``.
+
+    You must tell the middleware how many proxies set each header so it
+    knows what values to trust. It is a security issue to trust values
+    that came from the client rather than a proxy.
+
+    The original values of the headers are stored in the WSGI
+    environ as ``werkzeug.proxy_fix.orig``, a dict.
+
+    :param app: The WSGI application to wrap.
+    :param x_for: Number of values to trust for ``X-Forwarded-For``.
+    :param x_proto: Number of values to trust for ``X-Forwarded-Proto``.
+    :param x_host: Number of values to trust for ``X-Forwarded-Host``.
+    :param x_port: Number of values to trust for ``X-Forwarded-Port``.
+    :param x_prefix: Number of values to trust for
+        ``X-Forwarded-Prefix``.
+    :param num_proxies: Deprecated, use ``x_for`` instead.
+
+    .. code-block:: python
+
+        from werkzeug.middleware.proxy_fix import ProxyFix
+        # App is behind one proxy that sets the -For and -Host headers.
+        app = ProxyFix(app, x_for=1, x_host=1)
+
+    .. versionchanged:: 0.15
+        All headers support multiple values. The ``num_proxies``
+        argument is deprecated. Each header is configured with a
+        separate number of trusted proxies.
+
+    .. versionchanged:: 0.15
+        Original WSGI environ values are stored in the
+        ``werkzeug.proxy_fix.orig`` dict. ``orig_remote_addr``,
+        ``orig_wsgi_url_scheme``, and ``orig_http_host`` are deprecated
+        and will be removed in 1.0.
+
+    .. versionchanged:: 0.15
+        Support ``X-Forwarded-Port`` and ``X-Forwarded-Prefix``.
+
+    .. versionchanged:: 0.15
+        ``X-Fowarded-Host`` and ``X-Forwarded-Port`` modify
+        ``SERVER_NAME`` and ``SERVER_PORT``.
+    """
+
+    def __init__(
+        self, app, num_proxies=None, x_for=1, x_proto=0, x_host=0, x_port=0, x_prefix=0
+    ):
+        self.app = app
+        self.x_for = x_for
+        self.x_proto = x_proto
+        self.x_host = x_host
+        self.x_port = x_port
+        self.x_prefix = x_prefix
+        self.num_proxies = num_proxies
+
+    @property
+    def num_proxies(self):
+        """The number of proxies setting ``X-Forwarded-For`` in front
+        of the application.
+
+        .. deprecated:: 0.15
+            A separate number of trusted proxies is configured for each
+            header. ``num_proxies`` maps to ``x_for``. This method will
+            be removed in 1.0.
+
+        :internal:
+        """
+        warnings.warn(
+            "'num_proxies' is deprecated as of version 0.15 and will be"
+            " removed in version 1.0. Use 'x_for' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.x_for
+
+    @num_proxies.setter
+    def num_proxies(self, value):
+        if value is not None:
+            warnings.warn(
+                "'num_proxies' is deprecated as of version 0.15 and"
+                " will be removed in version 1.0. Use 'x_for' instead.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            self.x_for = value
+
+    def get_remote_addr(self, forwarded_for):
+        """Get the real ``remote_addr`` by looking backwards ``x_for``
+        number of values in the ``X-Forwarded-For`` header.
+
+        :param forwarded_for: List of values parsed from the
+            ``X-Forwarded-For`` header.
+        :return: The real ``remote_addr``, or ``None`` if there were not
+            at least ``x_for`` values.
+
+        .. deprecated:: 0.15
+            This is handled internally for each header. This method will
+            be removed in 1.0.
+
+        .. versionchanged:: 0.9
+            Use ``num_proxies`` instead of always picking the first
+            value.
+
+        .. versionadded:: 0.8
+        """
+        warnings.warn(
+            "'get_remote_addr' is deprecated as of version 0.15 and"
+            " will be removed in version 1.0. It is now handled"
+            " internally for each header.",
+            DeprecationWarning,
+        )
+        return self._get_trusted_comma(self.x_for, ",".join(forwarded_for))
+
+    def _get_trusted_comma(self, trusted, value):
+        """Get the real value from a comma-separated header based on the
+        configured number of trusted proxies.
+
+        :param trusted: Number of values to trust in the header.
+        :param value: Header value to parse.
+        :return: The real value, or ``None`` if there are fewer values
+            than the number of trusted proxies.
+
+        .. versionadded:: 0.15
+        """
+        if not (trusted and value):
+            return
+        values = [x.strip() for x in value.split(",")]
+        if len(values) >= trusted:
+            return values[-trusted]
+
+    def __call__(self, environ, start_response):
+        """Modify the WSGI environ based on the various ``Forwarded``
+        headers before calling the wrapped application. Store the
+        original environ values in ``werkzeug.proxy_fix.orig_{key}``.
+        """
+        environ_get = environ.get
+        orig_remote_addr = environ_get("REMOTE_ADDR")
+        orig_wsgi_url_scheme = environ_get("wsgi.url_scheme")
+        orig_http_host = environ_get("HTTP_HOST")
+        environ.update(
+            {
+                "werkzeug.proxy_fix.orig": {
+                    "REMOTE_ADDR": orig_remote_addr,
+                    "wsgi.url_scheme": orig_wsgi_url_scheme,
+                    "HTTP_HOST": orig_http_host,
+                    "SERVER_NAME": environ_get("SERVER_NAME"),
+                    "SERVER_PORT": environ_get("SERVER_PORT"),
+                    "SCRIPT_NAME": environ_get("SCRIPT_NAME"),
+                },
+                # todo: remove deprecated keys
+                "werkzeug.proxy_fix.orig_remote_addr": orig_remote_addr,
+                "werkzeug.proxy_fix.orig_wsgi_url_scheme": orig_wsgi_url_scheme,
+                "werkzeug.proxy_fix.orig_http_host": orig_http_host,
+            }
+        )
+
+        x_for = self._get_trusted_comma(self.x_for, environ_get("HTTP_X_FORWARDED_FOR"))
+        if x_for:
+            environ["REMOTE_ADDR"] = x_for
+
+        x_proto = self._get_trusted_comma(
+            self.x_proto, environ_get("HTTP_X_FORWARDED_PROTO")
+        )
+        if x_proto:
+            environ["wsgi.url_scheme"] = x_proto
+
+        x_host = self._get_trusted_comma(
+            self.x_host, environ_get("HTTP_X_FORWARDED_HOST")
+        )
+        if x_host:
+            environ["HTTP_HOST"] = x_host
+            parts = x_host.split(":", 1)
+            environ["SERVER_NAME"] = parts[0]
+            if len(parts) == 2:
+                environ["SERVER_PORT"] = parts[1]
+
+        x_port = self._get_trusted_comma(
+            self.x_port, environ_get("HTTP_X_FORWARDED_PORT")
+        )
+        if x_port:
+            host = environ.get("HTTP_HOST")
+            if host:
+                parts = host.split(":", 1)
+                host = parts[0] if len(parts) == 2 else host
+                environ["HTTP_HOST"] = "%s:%s" % (host, x_port)
+            environ["SERVER_PORT"] = x_port
+
+        x_prefix = self._get_trusted_comma(
+            self.x_prefix, environ_get("HTTP_X_FORWARDED_PREFIX")
+        )
+        if x_prefix:
+            environ["SCRIPT_NAME"] = x_prefix
+
+        return self.app(environ, start_response)
diff --git a/python/werkzeug/middleware/shared_data.py b/python/werkzeug/middleware/shared_data.py
new file mode 100644
index 0000000..a902281
--- /dev/null
+++ b/python/werkzeug/middleware/shared_data.py
@@ -0,0 +1,260 @@
+"""
+Serve Shared Static Files
+=========================
+
+.. autoclass:: SharedDataMiddleware
+    :members: is_allowed
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+import mimetypes
+import os
+import posixpath
+from datetime import datetime
+from io import BytesIO
+from time import mktime
+from time import time
+from zlib import adler32
+
+from .._compat import PY2
+from .._compat import string_types
+from ..filesystem import get_filesystem_encoding
+from ..http import http_date
+from ..http import is_resource_modified
+from ..wsgi import get_path_info
+from ..wsgi import wrap_file
+
+
+class SharedDataMiddleware(object):
+
+    """A WSGI middleware that provides static content for development
+    environments or simple server setups. Usage is quite simple::
+
+        import os
+        from werkzeug.wsgi import SharedDataMiddleware
+
+        app = SharedDataMiddleware(app, {
+            '/static': os.path.join(os.path.dirname(__file__), 'static')
+        })
+
+    The contents of the folder ``./shared`` will now be available on
+    ``http://example.com/shared/``.  This is pretty useful during development
+    because a standalone media server is not required.  One can also mount
+    files on the root folder and still continue to use the application because
+    the shared data middleware forwards all unhandled requests to the
+    application, even if the requests are below one of the shared folders.
+
+    If `pkg_resources` is available you can also tell the middleware to serve
+    files from package data::
+
+        app = SharedDataMiddleware(app, {
+            '/static': ('myapplication', 'static')
+        })
+
+    This will then serve the ``static`` folder in the `myapplication`
+    Python package.
+
+    The optional `disallow` parameter can be a list of :func:`~fnmatch.fnmatch`
+    rules for files that are not accessible from the web.  If `cache` is set to
+    `False` no caching headers are sent.
+
+    Currently the middleware does not support non ASCII filenames.  If the
+    encoding on the file system happens to be the encoding of the URI it may
+    work but this could also be by accident.  We strongly suggest using ASCII
+    only file names for static files.
+
+    The middleware will guess the mimetype using the Python `mimetype`
+    module.  If it's unable to figure out the charset it will fall back
+    to `fallback_mimetype`.
+
+    .. versionchanged:: 0.5
+       The cache timeout is configurable now.
+
+    .. versionadded:: 0.6
+       The `fallback_mimetype` parameter was added.
+
+    :param app: the application to wrap.  If you don't want to wrap an
+                application you can pass it :exc:`NotFound`.
+    :param exports: a list or dict of exported files and folders.
+    :param disallow: a list of :func:`~fnmatch.fnmatch` rules.
+    :param fallback_mimetype: the fallback mimetype for unknown files.
+    :param cache: enable or disable caching headers.
+    :param cache_timeout: the cache timeout in seconds for the headers.
+    """
+
+    def __init__(
+        self,
+        app,
+        exports,
+        disallow=None,
+        cache=True,
+        cache_timeout=60 * 60 * 12,
+        fallback_mimetype="text/plain",
+    ):
+        self.app = app
+        self.exports = []
+        self.cache = cache
+        self.cache_timeout = cache_timeout
+
+        if hasattr(exports, "items"):
+            exports = exports.items()
+
+        for key, value in exports:
+            if isinstance(value, tuple):
+                loader = self.get_package_loader(*value)
+            elif isinstance(value, string_types):
+                if os.path.isfile(value):
+                    loader = self.get_file_loader(value)
+                else:
+                    loader = self.get_directory_loader(value)
+            else:
+                raise TypeError("unknown def %r" % value)
+
+            self.exports.append((key, loader))
+
+        if disallow is not None:
+            from fnmatch import fnmatch
+
+            self.is_allowed = lambda x: not fnmatch(x, disallow)
+
+        self.fallback_mimetype = fallback_mimetype
+
+    def is_allowed(self, filename):
+        """Subclasses can override this method to disallow the access to
+        certain files.  However by providing `disallow` in the constructor
+        this method is overwritten.
+        """
+        return True
+
+    def _opener(self, filename):
+        return lambda: (
+            open(filename, "rb"),
+            datetime.utcfromtimestamp(os.path.getmtime(filename)),
+            int(os.path.getsize(filename)),
+        )
+
+    def get_file_loader(self, filename):
+        return lambda x: (os.path.basename(filename), self._opener(filename))
+
+    def get_package_loader(self, package, package_path):
+        from pkg_resources import DefaultProvider, ResourceManager, get_provider
+
+        loadtime = datetime.utcnow()
+        provider = get_provider(package)
+        manager = ResourceManager()
+        filesystem_bound = isinstance(provider, DefaultProvider)
+
+        def loader(path):
+            if path is None:
+                return None, None
+
+            path = posixpath.join(package_path, path)
+
+            if not provider.has_resource(path):
+                return None, None
+
+            basename = posixpath.basename(path)
+
+            if filesystem_bound:
+                return (
+                    basename,
+                    self._opener(provider.get_resource_filename(manager, path)),
+                )
+
+            s = provider.get_resource_string(manager, path)
+            return basename, lambda: (BytesIO(s), loadtime, len(s))
+
+        return loader
+
+    def get_directory_loader(self, directory):
+        def loader(path):
+            if path is not None:
+                path = os.path.join(directory, path)
+            else:
+                path = directory
+
+            if os.path.isfile(path):
+                return os.path.basename(path), self._opener(path)
+
+            return None, None
+
+        return loader
+
+    def generate_etag(self, mtime, file_size, real_filename):
+        if not isinstance(real_filename, bytes):
+            real_filename = real_filename.encode(get_filesystem_encoding())
+
+        return "wzsdm-%d-%s-%s" % (
+            mktime(mtime.timetuple()),
+            file_size,
+            adler32(real_filename) & 0xFFFFFFFF,
+        )
+
+    def __call__(self, environ, start_response):
+        cleaned_path = get_path_info(environ)
+
+        if PY2:
+            cleaned_path = cleaned_path.encode(get_filesystem_encoding())
+
+        # sanitize the path for non unix systems
+        cleaned_path = cleaned_path.strip("/")
+
+        for sep in os.sep, os.altsep:
+            if sep and sep != "/":
+                cleaned_path = cleaned_path.replace(sep, "/")
+
+        path = "/" + "/".join(x for x in cleaned_path.split("/") if x and x != "..")
+        file_loader = None
+
+        for search_path, loader in self.exports:
+            if search_path == path:
+                real_filename, file_loader = loader(None)
+
+                if file_loader is not None:
+                    break
+
+            if not search_path.endswith("/"):
+                search_path += "/"
+
+            if path.startswith(search_path):
+                real_filename, file_loader = loader(path[len(search_path) :])
+
+                if file_loader is not None:
+                    break
+
+        if file_loader is None or not self.is_allowed(real_filename):
+            return self.app(environ, start_response)
+
+        guessed_type = mimetypes.guess_type(real_filename)
+        mime_type = guessed_type[0] or self.fallback_mimetype
+        f, mtime, file_size = file_loader()
+
+        headers = [("Date", http_date())]
+
+        if self.cache:
+            timeout = self.cache_timeout
+            etag = self.generate_etag(mtime, file_size, real_filename)
+            headers += [
+                ("Etag", '"%s"' % etag),
+                ("Cache-Control", "max-age=%d, public" % timeout),
+            ]
+
+            if not is_resource_modified(environ, etag, last_modified=mtime):
+                f.close()
+                start_response("304 Not Modified", headers)
+                return []
+
+            headers.append(("Expires", http_date(time() + timeout)))
+        else:
+            headers.append(("Cache-Control", "public"))
+
+        headers.extend(
+            (
+                ("Content-Type", mime_type),
+                ("Content-Length", str(file_size)),
+                ("Last-Modified", http_date(mtime)),
+            )
+        )
+        start_response("200 OK", headers)
+        return wrap_file(environ, f)
diff --git a/python/werkzeug/posixemulation.py b/python/werkzeug/posixemulation.py
new file mode 100644
index 0000000..696b456
--- /dev/null
+++ b/python/werkzeug/posixemulation.py
@@ -0,0 +1,117 @@
+# -*- coding: utf-8 -*-
+r"""
+    werkzeug.posixemulation
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    Provides a POSIX emulation for some features that are relevant to
+    web applications.  The main purpose is to simplify support for
+    systems such as Windows NT that are not 100% POSIX compatible.
+
+    Currently this only implements a :func:`rename` function that
+    follows POSIX semantics.  Eg: if the target file already exists it
+    will be replaced without asking.
+
+    This module was introduced in 0.6.1 and is not a public interface.
+    It might become one in later versions of Werkzeug.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import errno
+import os
+import random
+import sys
+import time
+
+from ._compat import to_unicode
+from .filesystem import get_filesystem_encoding
+
+can_rename_open_file = False
+
+if os.name == "nt":
+    try:
+        import ctypes
+
+        _MOVEFILE_REPLACE_EXISTING = 0x1
+        _MOVEFILE_WRITE_THROUGH = 0x8
+        _MoveFileEx = ctypes.windll.kernel32.MoveFileExW
+
+        def _rename(src, dst):
+            src = to_unicode(src, get_filesystem_encoding())
+            dst = to_unicode(dst, get_filesystem_encoding())
+            if _rename_atomic(src, dst):
+                return True
+            retry = 0
+            rv = False
+            while not rv and retry < 100:
+                rv = _MoveFileEx(
+                    src, dst, _MOVEFILE_REPLACE_EXISTING | _MOVEFILE_WRITE_THROUGH
+                )
+                if not rv:
+                    time.sleep(0.001)
+                    retry += 1
+            return rv
+
+        # new in Vista and Windows Server 2008
+        _CreateTransaction = ctypes.windll.ktmw32.CreateTransaction
+        _CommitTransaction = ctypes.windll.ktmw32.CommitTransaction
+        _MoveFileTransacted = ctypes.windll.kernel32.MoveFileTransactedW
+        _CloseHandle = ctypes.windll.kernel32.CloseHandle
+        can_rename_open_file = True
+
+        def _rename_atomic(src, dst):
+            ta = _CreateTransaction(None, 0, 0, 0, 0, 1000, "Werkzeug rename")
+            if ta == -1:
+                return False
+            try:
+                retry = 0
+                rv = False
+                while not rv and retry < 100:
+                    rv = _MoveFileTransacted(
+                        src,
+                        dst,
+                        None,
+                        None,
+                        _MOVEFILE_REPLACE_EXISTING | _MOVEFILE_WRITE_THROUGH,
+                        ta,
+                    )
+                    if rv:
+                        rv = _CommitTransaction(ta)
+                        break
+                    else:
+                        time.sleep(0.001)
+                        retry += 1
+                return rv
+            finally:
+                _CloseHandle(ta)
+
+    except Exception:
+
+        def _rename(src, dst):
+            return False
+
+        def _rename_atomic(src, dst):
+            return False
+
+    def rename(src, dst):
+        # Try atomic or pseudo-atomic rename
+        if _rename(src, dst):
+            return
+        # Fall back to "move away and replace"
+        try:
+            os.rename(src, dst)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+            old = "%s-%08x" % (dst, random.randint(0, sys.maxsize))
+            os.rename(dst, old)
+            os.rename(src, dst)
+            try:
+                os.unlink(old)
+            except Exception:
+                pass
+
+
+else:
+    rename = os.rename
+    can_rename_open_file = True
diff --git a/python/werkzeug/routing.py b/python/werkzeug/routing.py
new file mode 100644
index 0000000..6b1dd98
--- /dev/null
+++ b/python/werkzeug/routing.py
@@ -0,0 +1,2026 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.routing
+    ~~~~~~~~~~~~~~~~
+
+    When it comes to combining multiple controller or view functions (however
+    you want to call them) you need a dispatcher.  A simple way would be
+    applying regular expression tests on the ``PATH_INFO`` and calling
+    registered callback functions that return the value then.
+
+    This module implements a much more powerful system than simple regular
+    expression matching because it can also convert values in the URLs and
+    build URLs.
+
+    Here a simple example that creates an URL map for an application with
+    two subdomains (www and kb) and some URL rules:
+
+    >>> m = Map([
+    ...     # Static URLs
+    ...     Rule('/', endpoint='static/index'),
+    ...     Rule('/about', endpoint='static/about'),
+    ...     Rule('/help', endpoint='static/help'),
+    ...     # Knowledge Base
+    ...     Subdomain('kb', [
+    ...         Rule('/', endpoint='kb/index'),
+    ...         Rule('/browse/', endpoint='kb/browse'),
+    ...         Rule('/browse/<int:id>/', endpoint='kb/browse'),
+    ...         Rule('/browse/<int:id>/<int:page>', endpoint='kb/browse')
+    ...     ])
+    ... ], default_subdomain='www')
+
+    If the application doesn't use subdomains it's perfectly fine to not set
+    the default subdomain and not use the `Subdomain` rule factory.  The endpoint
+    in the rules can be anything, for example import paths or unique
+    identifiers.  The WSGI application can use those endpoints to get the
+    handler for that URL.  It doesn't have to be a string at all but it's
+    recommended.
+
+    Now it's possible to create a URL adapter for one of the subdomains and
+    build URLs:
+
+    >>> c = m.bind('example.com')
+    >>> c.build("kb/browse", dict(id=42))
+    'http://kb.example.com/browse/42/'
+    >>> c.build("kb/browse", dict())
+    'http://kb.example.com/browse/'
+    >>> c.build("kb/browse", dict(id=42, page=3))
+    'http://kb.example.com/browse/42/3'
+    >>> c.build("static/about")
+    '/about'
+    >>> c.build("static/index", force_external=True)
+    'http://www.example.com/'
+
+    >>> c = m.bind('example.com', subdomain='kb')
+    >>> c.build("static/about")
+    'http://www.example.com/about'
+
+    The first argument to bind is the server name *without* the subdomain.
+    Per default it will assume that the script is mounted on the root, but
+    often that's not the case so you can provide the real mount point as
+    second argument:
+
+    >>> c = m.bind('example.com', '/applications/example')
+
+    The third argument can be the subdomain, if not given the default
+    subdomain is used.  For more details about binding have a look at the
+    documentation of the `MapAdapter`.
+
+    And here is how you can match URLs:
+
+    >>> c = m.bind('example.com')
+    >>> c.match("/")
+    ('static/index', {})
+    >>> c.match("/about")
+    ('static/about', {})
+    >>> c = m.bind('example.com', '/', 'kb')
+    >>> c.match("/")
+    ('kb/index', {})
+    >>> c.match("/browse/42/23")
+    ('kb/browse', {'id': 42, 'page': 23})
+
+    If matching fails you get a `NotFound` exception, if the rule thinks
+    it's a good idea to redirect (for example because the URL was defined
+    to have a slash at the end but the request was missing that slash) it
+    will raise a `RequestRedirect` exception.  Both are subclasses of the
+    `HTTPException` so you can use those errors as responses in the
+    application.
+
+    If matching succeeded but the URL rule was incompatible to the given
+    method (for example there were only rules for `GET` and `HEAD` and
+    routing system tried to match a `POST` request) a `MethodNotAllowed`
+    exception is raised.
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import ast
+import difflib
+import posixpath
+import re
+import uuid
+from pprint import pformat
+from threading import Lock
+
+from ._compat import implements_to_string
+from ._compat import iteritems
+from ._compat import itervalues
+from ._compat import native_string_result
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import to_bytes
+from ._compat import to_unicode
+from ._compat import wsgi_decoding_dance
+from ._internal import _encode_idna
+from ._internal import _get_environ
+from .datastructures import ImmutableDict
+from .datastructures import MultiDict
+from .exceptions import BadHost
+from .exceptions import HTTPException
+from .exceptions import MethodNotAllowed
+from .exceptions import NotFound
+from .urls import _fast_url_quote
+from .urls import url_encode
+from .urls import url_join
+from .urls import url_quote
+from .utils import cached_property
+from .utils import format_string
+from .utils import redirect
+from .wsgi import get_host
+
+_rule_re = re.compile(
+    r"""
+    (?P<static>[^<]*)                           # static rule data
+    <
+    (?:
+        (?P<converter>[a-zA-Z_][a-zA-Z0-9_]*)   # converter name
+        (?:\((?P<args>.*?)\))?                  # converter arguments
+        \:                                      # variable delimiter
+    )?
+    (?P<variable>[a-zA-Z_][a-zA-Z0-9_]*)        # variable name
+    >
+    """,
+    re.VERBOSE,
+)
+_simple_rule_re = re.compile(r"<([^>]+)>")
+_converter_args_re = re.compile(
+    r"""
+    ((?P<name>\w+)\s*=\s*)?
+    (?P<value>
+        True|False|
+        \d+.\d+|
+        \d+.|
+        \d+|
+        [\w\d_.]+|
+        [urUR]?(?P<stringval>"[^"]*?"|'[^']*')
+    )\s*,
+    """,
+    re.VERBOSE | re.UNICODE,
+)
+
+
+_PYTHON_CONSTANTS = {"None": None, "True": True, "False": False}
+
+
+def _pythonize(value):
+    if value in _PYTHON_CONSTANTS:
+        return _PYTHON_CONSTANTS[value]
+    for convert in int, float:
+        try:
+            return convert(value)
+        except ValueError:
+            pass
+    if value[:1] == value[-1:] and value[0] in "\"'":
+        value = value[1:-1]
+    return text_type(value)
+
+
+def parse_converter_args(argstr):
+    argstr += ","
+    args = []
+    kwargs = {}
+
+    for item in _converter_args_re.finditer(argstr):
+        value = item.group("stringval")
+        if value is None:
+            value = item.group("value")
+        value = _pythonize(value)
+        if not item.group("name"):
+            args.append(value)
+        else:
+            name = item.group("name")
+            kwargs[name] = value
+
+    return tuple(args), kwargs
+
+
+def parse_rule(rule):
+    """Parse a rule and return it as generator. Each iteration yields tuples
+    in the form ``(converter, arguments, variable)``. If the converter is
+    `None` it's a static url part, otherwise it's a dynamic one.
+
+    :internal:
+    """
+    pos = 0
+    end = len(rule)
+    do_match = _rule_re.match
+    used_names = set()
+    while pos < end:
+        m = do_match(rule, pos)
+        if m is None:
+            break
+        data = m.groupdict()
+        if data["static"]:
+            yield None, None, data["static"]
+        variable = data["variable"]
+        converter = data["converter"] or "default"
+        if variable in used_names:
+            raise ValueError("variable name %r used twice." % variable)
+        used_names.add(variable)
+        yield converter, data["args"] or None, variable
+        pos = m.end()
+    if pos < end:
+        remaining = rule[pos:]
+        if ">" in remaining or "<" in remaining:
+            raise ValueError("malformed url rule: %r" % rule)
+        yield None, None, remaining
+
+
+class RoutingException(Exception):
+    """Special exceptions that require the application to redirect, notifying
+    about missing urls, etc.
+
+    :internal:
+    """
+
+
+class RequestRedirect(HTTPException, RoutingException):
+    """Raise if the map requests a redirect. This is for example the case if
+    `strict_slashes` are activated and an url that requires a trailing slash.
+
+    The attribute `new_url` contains the absolute destination url.
+    """
+
+    code = 308
+
+    def __init__(self, new_url):
+        RoutingException.__init__(self, new_url)
+        self.new_url = new_url
+
+    def get_response(self, environ):
+        return redirect(self.new_url, self.code)
+
+
+class RequestSlash(RoutingException):
+    """Internal exception."""
+
+
+class RequestAliasRedirect(RoutingException):  # noqa: B903
+    """This rule is an alias and wants to redirect to the canonical URL."""
+
+    def __init__(self, matched_values):
+        self.matched_values = matched_values
+
+
+@implements_to_string
+class BuildError(RoutingException, LookupError):
+    """Raised if the build system cannot find a URL for an endpoint with the
+    values provided.
+    """
+
+    def __init__(self, endpoint, values, method, adapter=None):
+        LookupError.__init__(self, endpoint, values, method)
+        self.endpoint = endpoint
+        self.values = values
+        self.method = method
+        self.adapter = adapter
+
+    @cached_property
+    def suggested(self):
+        return self.closest_rule(self.adapter)
+
+    def closest_rule(self, adapter):
+        def _score_rule(rule):
+            return sum(
+                [
+                    0.98
+                    * difflib.SequenceMatcher(
+                        None, rule.endpoint, self.endpoint
+                    ).ratio(),
+                    0.01 * bool(set(self.values or ()).issubset(rule.arguments)),
+                    0.01 * bool(rule.methods and self.method in rule.methods),
+                ]
+            )
+
+        if adapter and adapter.map._rules:
+            return max(adapter.map._rules, key=_score_rule)
+
+    def __str__(self):
+        message = []
+        message.append("Could not build url for endpoint %r" % self.endpoint)
+        if self.method:
+            message.append(" (%r)" % self.method)
+        if self.values:
+            message.append(" with values %r" % sorted(self.values.keys()))
+        message.append(".")
+        if self.suggested:
+            if self.endpoint == self.suggested.endpoint:
+                if self.method and self.method not in self.suggested.methods:
+                    message.append(
+                        " Did you mean to use methods %r?"
+                        % sorted(self.suggested.methods)
+                    )
+                missing_values = self.suggested.arguments.union(
+                    set(self.suggested.defaults or ())
+                ) - set(self.values.keys())
+                if missing_values:
+                    message.append(
+                        " Did you forget to specify values %r?" % sorted(missing_values)
+                    )
+            else:
+                message.append(" Did you mean %r instead?" % self.suggested.endpoint)
+        return u"".join(message)
+
+
+class ValidationError(ValueError):
+    """Validation error.  If a rule converter raises this exception the rule
+    does not match the current URL and the next URL is tried.
+    """
+
+
+class RuleFactory(object):
+    """As soon as you have more complex URL setups it's a good idea to use rule
+    factories to avoid repetitive tasks.  Some of them are builtin, others can
+    be added by subclassing `RuleFactory` and overriding `get_rules`.
+    """
+
+    def get_rules(self, map):
+        """Subclasses of `RuleFactory` have to override this method and return
+        an iterable of rules."""
+        raise NotImplementedError()
+
+
+class Subdomain(RuleFactory):
+    """All URLs provided by this factory have the subdomain set to a
+    specific domain. For example if you want to use the subdomain for
+    the current language this can be a good setup::
+
+        url_map = Map([
+            Rule('/', endpoint='#select_language'),
+            Subdomain('<string(length=2):lang_code>', [
+                Rule('/', endpoint='index'),
+                Rule('/about', endpoint='about'),
+                Rule('/help', endpoint='help')
+            ])
+        ])
+
+    All the rules except for the ``'#select_language'`` endpoint will now
+    listen on a two letter long subdomain that holds the language code
+    for the current request.
+    """
+
+    def __init__(self, subdomain, rules):
+        self.subdomain = subdomain
+        self.rules = rules
+
+    def get_rules(self, map):
+        for rulefactory in self.rules:
+            for rule in rulefactory.get_rules(map):
+                rule = rule.empty()
+                rule.subdomain = self.subdomain
+                yield rule
+
+
+class Submount(RuleFactory):
+    """Like `Subdomain` but prefixes the URL rule with a given string::
+
+        url_map = Map([
+            Rule('/', endpoint='index'),
+            Submount('/blog', [
+                Rule('/', endpoint='blog/index'),
+                Rule('/entry/<entry_slug>', endpoint='blog/show')
+            ])
+        ])
+
+    Now the rule ``'blog/show'`` matches ``/blog/entry/<entry_slug>``.
+    """
+
+    def __init__(self, path, rules):
+        self.path = path.rstrip("/")
+        self.rules = rules
+
+    def get_rules(self, map):
+        for rulefactory in self.rules:
+            for rule in rulefactory.get_rules(map):
+                rule = rule.empty()
+                rule.rule = self.path + rule.rule
+                yield rule
+
+
+class EndpointPrefix(RuleFactory):
+    """Prefixes all endpoints (which must be strings for this factory) with
+    another string. This can be useful for sub applications::
+
+        url_map = Map([
+            Rule('/', endpoint='index'),
+            EndpointPrefix('blog/', [Submount('/blog', [
+                Rule('/', endpoint='index'),
+                Rule('/entry/<entry_slug>', endpoint='show')
+            ])])
+        ])
+    """
+
+    def __init__(self, prefix, rules):
+        self.prefix = prefix
+        self.rules = rules
+
+    def get_rules(self, map):
+        for rulefactory in self.rules:
+            for rule in rulefactory.get_rules(map):
+                rule = rule.empty()
+                rule.endpoint = self.prefix + rule.endpoint
+                yield rule
+
+
+class RuleTemplate(object):
+    """Returns copies of the rules wrapped and expands string templates in
+    the endpoint, rule, defaults or subdomain sections.
+
+    Here a small example for such a rule template::
+
+        from werkzeug.routing import Map, Rule, RuleTemplate
+
+        resource = RuleTemplate([
+            Rule('/$name/', endpoint='$name.list'),
+            Rule('/$name/<int:id>', endpoint='$name.show')
+        ])
+
+        url_map = Map([resource(name='user'), resource(name='page')])
+
+    When a rule template is called the keyword arguments are used to
+    replace the placeholders in all the string parameters.
+    """
+
+    def __init__(self, rules):
+        self.rules = list(rules)
+
+    def __call__(self, *args, **kwargs):
+        return RuleTemplateFactory(self.rules, dict(*args, **kwargs))
+
+
+class RuleTemplateFactory(RuleFactory):
+    """A factory that fills in template variables into rules.  Used by
+    `RuleTemplate` internally.
+
+    :internal:
+    """
+
+    def __init__(self, rules, context):
+        self.rules = rules
+        self.context = context
+
+    def get_rules(self, map):
+        for rulefactory in self.rules:
+            for rule in rulefactory.get_rules(map):
+                new_defaults = subdomain = None
+                if rule.defaults:
+                    new_defaults = {}
+                    for key, value in iteritems(rule.defaults):
+                        if isinstance(value, string_types):
+                            value = format_string(value, self.context)
+                        new_defaults[key] = value
+                if rule.subdomain is not None:
+                    subdomain = format_string(rule.subdomain, self.context)
+                new_endpoint = rule.endpoint
+                if isinstance(new_endpoint, string_types):
+                    new_endpoint = format_string(new_endpoint, self.context)
+                yield Rule(
+                    format_string(rule.rule, self.context),
+                    new_defaults,
+                    subdomain,
+                    rule.methods,
+                    rule.build_only,
+                    new_endpoint,
+                    rule.strict_slashes,
+                )
+
+
+def _prefix_names(src):
+    """ast parse and prefix names with `.` to avoid collision with user vars"""
+    tree = ast.parse(src).body[0]
+    if isinstance(tree, ast.Expr):
+        tree = tree.value
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Name):
+            node.id = "." + node.id
+    return tree
+
+
+_CALL_CONVERTER_CODE_FMT = "self._converters[{elem!r}].to_url()"
+_IF_KWARGS_URL_ENCODE_CODE = """\
+if kwargs:
+    q = '?'
+    params = self._encode_query_vars(kwargs)
+else:
+    q = params = ''
+"""
+_IF_KWARGS_URL_ENCODE_AST = _prefix_names(_IF_KWARGS_URL_ENCODE_CODE)
+_URL_ENCODE_AST_NAMES = (_prefix_names("q"), _prefix_names("params"))
+
+
+@implements_to_string
+class Rule(RuleFactory):
+    """A Rule represents one URL pattern.  There are some options for `Rule`
+    that change the way it behaves and are passed to the `Rule` constructor.
+    Note that besides the rule-string all arguments *must* be keyword arguments
+    in order to not break the application on Werkzeug upgrades.
+
+    `string`
+        Rule strings basically are just normal URL paths with placeholders in
+        the format ``<converter(arguments):name>`` where the converter and the
+        arguments are optional.  If no converter is defined the `default`
+        converter is used which means `string` in the normal configuration.
+
+        URL rules that end with a slash are branch URLs, others are leaves.
+        If you have `strict_slashes` enabled (which is the default), all
+        branch URLs that are matched without a trailing slash will trigger a
+        redirect to the same URL with the missing slash appended.
+
+        The converters are defined on the `Map`.
+
+    `endpoint`
+        The endpoint for this rule. This can be anything. A reference to a
+        function, a string, a number etc.  The preferred way is using a string
+        because the endpoint is used for URL generation.
+
+    `defaults`
+        An optional dict with defaults for other rules with the same endpoint.
+        This is a bit tricky but useful if you want to have unique URLs::
+
+            url_map = Map([
+                Rule('/all/', defaults={'page': 1}, endpoint='all_entries'),
+                Rule('/all/page/<int:page>', endpoint='all_entries')
+            ])
+
+        If a user now visits ``http://example.com/all/page/1`` he will be
+        redirected to ``http://example.com/all/``.  If `redirect_defaults` is
+        disabled on the `Map` instance this will only affect the URL
+        generation.
+
+    `subdomain`
+        The subdomain rule string for this rule. If not specified the rule
+        only matches for the `default_subdomain` of the map.  If the map is
+        not bound to a subdomain this feature is disabled.
+
+        Can be useful if you want to have user profiles on different subdomains
+        and all subdomains are forwarded to your application::
+
+            url_map = Map([
+                Rule('/', subdomain='<username>', endpoint='user/homepage'),
+                Rule('/stats', subdomain='<username>', endpoint='user/stats')
+            ])
+
+    `methods`
+        A sequence of http methods this rule applies to.  If not specified, all
+        methods are allowed. For example this can be useful if you want different
+        endpoints for `POST` and `GET`.  If methods are defined and the path
+        matches but the method matched against is not in this list or in the
+        list of another rule for that path the error raised is of the type
+        `MethodNotAllowed` rather than `NotFound`.  If `GET` is present in the
+        list of methods and `HEAD` is not, `HEAD` is added automatically.
+
+        .. versionchanged:: 0.6.1
+           `HEAD` is now automatically added to the methods if `GET` is
+           present.  The reason for this is that existing code often did not
+           work properly in servers not rewriting `HEAD` to `GET`
+           automatically and it was not documented how `HEAD` should be
+           treated.  This was considered a bug in Werkzeug because of that.
+
+    `strict_slashes`
+        Override the `Map` setting for `strict_slashes` only for this rule. If
+        not specified the `Map` setting is used.
+
+    `build_only`
+        Set this to True and the rule will never match but will create a URL
+        that can be build. This is useful if you have resources on a subdomain
+        or folder that are not handled by the WSGI application (like static data)
+
+    `redirect_to`
+        If given this must be either a string or callable.  In case of a
+        callable it's called with the url adapter that triggered the match and
+        the values of the URL as keyword arguments and has to return the target
+        for the redirect, otherwise it has to be a string with placeholders in
+        rule syntax::
+
+            def foo_with_slug(adapter, id):
+                # ask the database for the slug for the old id.  this of
+                # course has nothing to do with werkzeug.
+                return 'foo/' + Foo.get_slug_for_id(id)
+
+            url_map = Map([
+                Rule('/foo/<slug>', endpoint='foo'),
+                Rule('/some/old/url/<slug>', redirect_to='foo/<slug>'),
+                Rule('/other/old/url/<int:id>', redirect_to=foo_with_slug)
+            ])
+
+        When the rule is matched the routing system will raise a
+        `RequestRedirect` exception with the target for the redirect.
+
+        Keep in mind that the URL will be joined against the URL root of the
+        script so don't use a leading slash on the target URL unless you
+        really mean root of that domain.
+
+    `alias`
+        If enabled this rule serves as an alias for another rule with the same
+        endpoint and arguments.
+
+    `host`
+        If provided and the URL map has host matching enabled this can be
+        used to provide a match rule for the whole host.  This also means
+        that the subdomain feature is disabled.
+
+    .. versionadded:: 0.7
+       The `alias` and `host` parameters were added.
+    """
+
+    def __init__(
+        self,
+        string,
+        defaults=None,
+        subdomain=None,
+        methods=None,
+        build_only=False,
+        endpoint=None,
+        strict_slashes=None,
+        redirect_to=None,
+        alias=False,
+        host=None,
+    ):
+        if not string.startswith("/"):
+            raise ValueError("urls must start with a leading slash")
+        self.rule = string
+        self.is_leaf = not string.endswith("/")
+
+        self.map = None
+        self.strict_slashes = strict_slashes
+        self.subdomain = subdomain
+        self.host = host
+        self.defaults = defaults
+        self.build_only = build_only
+        self.alias = alias
+        if methods is None:
+            self.methods = None
+        else:
+            if isinstance(methods, str):
+                raise TypeError("param `methods` should be `Iterable[str]`, not `str`")
+            self.methods = set([x.upper() for x in methods])
+            if "HEAD" not in self.methods and "GET" in self.methods:
+                self.methods.add("HEAD")
+        self.endpoint = endpoint
+        self.redirect_to = redirect_to
+
+        if defaults:
+            self.arguments = set(map(str, defaults))
+        else:
+            self.arguments = set()
+        self._trace = self._converters = self._regex = self._argument_weights = None
+
+    def empty(self):
+        """
+        Return an unbound copy of this rule.
+
+        This can be useful if want to reuse an already bound URL for another
+        map.  See ``get_empty_kwargs`` to override what keyword arguments are
+        provided to the new copy.
+        """
+        return type(self)(self.rule, **self.get_empty_kwargs())
+
+    def get_empty_kwargs(self):
+        """
+        Provides kwargs for instantiating empty copy with empty()
+
+        Use this method to provide custom keyword arguments to the subclass of
+        ``Rule`` when calling ``some_rule.empty()``.  Helpful when the subclass
+        has custom keyword arguments that are needed at instantiation.
+
+        Must return a ``dict`` that will be provided as kwargs to the new
+        instance of ``Rule``, following the initial ``self.rule`` value which
+        is always provided as the first, required positional argument.
+        """
+        defaults = None
+        if self.defaults:
+            defaults = dict(self.defaults)
+        return dict(
+            defaults=defaults,
+            subdomain=self.subdomain,
+            methods=self.methods,
+            build_only=self.build_only,
+            endpoint=self.endpoint,
+            strict_slashes=self.strict_slashes,
+            redirect_to=self.redirect_to,
+            alias=self.alias,
+            host=self.host,
+        )
+
+    def get_rules(self, map):
+        yield self
+
+    def refresh(self):
+        """Rebinds and refreshes the URL.  Call this if you modified the
+        rule in place.
+
+        :internal:
+        """
+        self.bind(self.map, rebind=True)
+
+    def bind(self, map, rebind=False):
+        """Bind the url to a map and create a regular expression based on
+        the information from the rule itself and the defaults from the map.
+
+        :internal:
+        """
+        if self.map is not None and not rebind:
+            raise RuntimeError("url rule %r already bound to map %r" % (self, self.map))
+        self.map = map
+        if self.strict_slashes is None:
+            self.strict_slashes = map.strict_slashes
+        if self.subdomain is None:
+            self.subdomain = map.default_subdomain
+        self.compile()
+
+    def get_converter(self, variable_name, converter_name, args, kwargs):
+        """Looks up the converter for the given parameter.
+
+        .. versionadded:: 0.9
+        """
+        if converter_name not in self.map.converters:
+            raise LookupError("the converter %r does not exist" % converter_name)
+        return self.map.converters[converter_name](self.map, *args, **kwargs)
+
+    def _encode_query_vars(self, query_vars):
+        return url_encode(
+            query_vars,
+            charset=self.map.charset,
+            sort=self.map.sort_parameters,
+            key=self.map.sort_key,
+        )
+
+    def compile(self):
+        """Compiles the regular expression and stores it."""
+        assert self.map is not None, "rule not bound"
+
+        if self.map.host_matching:
+            domain_rule = self.host or ""
+        else:
+            domain_rule = self.subdomain or ""
+
+        self._trace = []
+        self._converters = {}
+        self._static_weights = []
+        self._argument_weights = []
+        regex_parts = []
+
+        def _build_regex(rule):
+            index = 0
+            for converter, arguments, variable in parse_rule(rule):
+                if converter is None:
+                    regex_parts.append(re.escape(variable))
+                    self._trace.append((False, variable))
+                    for part in variable.split("/"):
+                        if part:
+                            self._static_weights.append((index, -len(part)))
+                else:
+                    if arguments:
+                        c_args, c_kwargs = parse_converter_args(arguments)
+                    else:
+                        c_args = ()
+                        c_kwargs = {}
+                    convobj = self.get_converter(variable, converter, c_args, c_kwargs)
+                    regex_parts.append("(?P<%s>%s)" % (variable, convobj.regex))
+                    self._converters[variable] = convobj
+                    self._trace.append((True, variable))
+                    self._argument_weights.append(convobj.weight)
+                    self.arguments.add(str(variable))
+                index = index + 1
+
+        _build_regex(domain_rule)
+        regex_parts.append("\\|")
+        self._trace.append((False, "|"))
+        _build_regex(self.rule if self.is_leaf else self.rule.rstrip("/"))
+        if not self.is_leaf:
+            self._trace.append((False, "/"))
+
+        self._build = self._compile_builder(False).__get__(self, None)
+        self._build_unknown = self._compile_builder(True).__get__(self, None)
+
+        if self.build_only:
+            return
+        regex = r"^%s%s$" % (
+            u"".join(regex_parts),
+            (not self.is_leaf or not self.strict_slashes)
+            and "(?<!/)(?P<__suffix__>/?)"
+            or "",
+        )
+        self._regex = re.compile(regex, re.UNICODE)
+
+    def match(self, path, method=None):
+        """Check if the rule matches a given path. Path is a string in the
+        form ``"subdomain|/path"`` and is assembled by the map.  If
+        the map is doing host matching the subdomain part will be the host
+        instead.
+
+        If the rule matches a dict with the converted values is returned,
+        otherwise the return value is `None`.
+
+        :internal:
+        """
+        if not self.build_only:
+            m = self._regex.search(path)
+            if m is not None:
+                groups = m.groupdict()
+                # we have a folder like part of the url without a trailing
+                # slash and strict slashes enabled. raise an exception that
+                # tells the map to redirect to the same url but with a
+                # trailing slash
+                if (
+                    self.strict_slashes
+                    and not self.is_leaf
+                    and not groups.pop("__suffix__")
+                    and (
+                        method is None or self.methods is None or method in self.methods
+                    )
+                ):
+                    raise RequestSlash()
+                # if we are not in strict slashes mode we have to remove
+                # a __suffix__
+                elif not self.strict_slashes:
+                    del groups["__suffix__"]
+
+                result = {}
+                for name, value in iteritems(groups):
+                    try:
+                        value = self._converters[name].to_python(value)
+                    except ValidationError:
+                        return
+                    result[str(name)] = value
+                if self.defaults:
+                    result.update(self.defaults)
+
+                if self.alias and self.map.redirect_defaults:
+                    raise RequestAliasRedirect(result)
+
+                return result
+
+    @staticmethod
+    def _get_func_code(code, name):
+        globs, locs = {}, {}
+        exec(code, globs, locs)
+        return locs[name]
+
+    def _compile_builder(self, append_unknown=True):
+        defaults = self.defaults or {}
+        dom_ops = []
+        url_ops = []
+
+        opl = dom_ops
+        for is_dynamic, data in self._trace:
+            if data == "|" and opl is dom_ops:
+                opl = url_ops
+                continue
+            # this seems like a silly case to ever come up but:
+            # if a default is given for a value that appears in the rule,
+            # resolve it to a constant ahead of time
+            if is_dynamic and data in defaults:
+                data = self._converters[data].to_url(defaults[data])
+                opl.append((False, data))
+            elif not is_dynamic:
+                opl.append(
+                    (False, url_quote(to_bytes(data, self.map.charset), safe="/:|+"))
+                )
+            else:
+                opl.append((True, data))
+
+        def _convert(elem):
+            ret = _prefix_names(_CALL_CONVERTER_CODE_FMT.format(elem=elem))
+            ret.args = [ast.Name(str(elem), ast.Load())]  # str for py2
+            return ret
+
+        def _parts(ops):
+            parts = [
+                _convert(elem) if is_dynamic else ast.Str(s=elem)
+                for is_dynamic, elem in ops
+            ]
+            parts = parts or [ast.Str("")]
+            # constant fold
+            ret = [parts[0]]
+            for p in parts[1:]:
+                if isinstance(p, ast.Str) and isinstance(ret[-1], ast.Str):
+                    ret[-1] = ast.Str(ret[-1].s + p.s)
+                else:
+                    ret.append(p)
+            return ret
+
+        dom_parts = _parts(dom_ops)
+        url_parts = _parts(url_ops)
+        if not append_unknown:
+            body = []
+        else:
+            body = [_IF_KWARGS_URL_ENCODE_AST]
+            url_parts.extend(_URL_ENCODE_AST_NAMES)
+
+        def _join(parts):
+            if len(parts) == 1:  # shortcut
+                return parts[0]
+            elif hasattr(ast, "JoinedStr"):  # py36+
+                return ast.JoinedStr(parts)
+            else:
+                call = _prefix_names('"".join()')
+                call.args = [ast.Tuple(parts, ast.Load())]
+                return call
+
+        body.append(
+            ast.Return(ast.Tuple([_join(dom_parts), _join(url_parts)], ast.Load()))
+        )
+
+        # str is necessary for python2
+        pargs = [
+            str(elem)
+            for is_dynamic, elem in dom_ops + url_ops
+            if is_dynamic and elem not in defaults
+        ]
+        kargs = [str(k) for k in defaults]
+
+        func_ast = _prefix_names("def _(): pass")
+        func_ast.name = "<builder:{!r}>".format(self.rule)
+        if hasattr(ast, "arg"):  # py3
+            func_ast.args.args.append(ast.arg(".self", None))
+            for arg in pargs + kargs:
+                func_ast.args.args.append(ast.arg(arg, None))
+            func_ast.args.kwarg = ast.arg(".kwargs", None)
+        else:
+            func_ast.args.args.append(ast.Name(".self", ast.Load()))
+            for arg in pargs + kargs:
+                func_ast.args.args.append(ast.Name(arg, ast.Load()))
+            func_ast.args.kwarg = ".kwargs"
+        for _ in kargs:
+            func_ast.args.defaults.append(ast.Str(""))
+        func_ast.body = body
+
+        module = ast.fix_missing_locations(ast.Module([func_ast]))
+        code = compile(module, "<werkzeug routing>", "exec")
+        return self._get_func_code(code, func_ast.name)
+
+    def build(self, values, append_unknown=True):
+        """Assembles the relative url for that rule and the subdomain.
+        If building doesn't work for some reasons `None` is returned.
+
+        :internal:
+        """
+        try:
+            if append_unknown:
+                return self._build_unknown(**values)
+            else:
+                return self._build(**values)
+        except ValidationError:
+            return None
+
+    def provides_defaults_for(self, rule):
+        """Check if this rule has defaults for a given rule.
+
+        :internal:
+        """
+        return (
+            not self.build_only
+            and self.defaults
+            and self.endpoint == rule.endpoint
+            and self != rule
+            and self.arguments == rule.arguments
+        )
+
+    def suitable_for(self, values, method=None):
+        """Check if the dict of values has enough data for url generation.
+
+        :internal:
+        """
+        # if a method was given explicitly and that method is not supported
+        # by this rule, this rule is not suitable.
+        if (
+            method is not None
+            and self.methods is not None
+            and method not in self.methods
+        ):
+            return False
+
+        defaults = self.defaults or ()
+
+        # all arguments required must be either in the defaults dict or
+        # the value dictionary otherwise it's not suitable
+        for key in self.arguments:
+            if key not in defaults and key not in values:
+                return False
+
+        # in case defaults are given we ensure that either the value was
+        # skipped or the value is the same as the default value.
+        if defaults:
+            for key, value in iteritems(defaults):
+                if key in values and value != values[key]:
+                    return False
+
+        return True
+
+    def match_compare_key(self):
+        """The match compare key for sorting.
+
+        Current implementation:
+
+        1.  rules without any arguments come first for performance
+            reasons only as we expect them to match faster and some
+            common ones usually don't have any arguments (index pages etc.)
+        2.  rules with more static parts come first so the second argument
+            is the negative length of the number of the static weights.
+        3.  we order by static weights, which is a combination of index
+            and length
+        4.  The more complex rules come first so the next argument is the
+            negative length of the number of argument weights.
+        5.  lastly we order by the actual argument weights.
+
+        :internal:
+        """
+        return (
+            bool(self.arguments),
+            -len(self._static_weights),
+            self._static_weights,
+            -len(self._argument_weights),
+            self._argument_weights,
+        )
+
+    def build_compare_key(self):
+        """The build compare key for sorting.
+
+        :internal:
+        """
+        return 1 if self.alias else 0, -len(self.arguments), -len(self.defaults or ())
+
+    def __eq__(self, other):
+        return self.__class__ is other.__class__ and self._trace == other._trace
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __str__(self):
+        return self.rule
+
+    @native_string_result
+    def __repr__(self):
+        if self.map is None:
+            return u"<%s (unbound)>" % self.__class__.__name__
+        tmp = []
+        for is_dynamic, data in self._trace:
+            if is_dynamic:
+                tmp.append(u"<%s>" % data)
+            else:
+                tmp.append(data)
+        return u"<%s %s%s -> %s>" % (
+            self.__class__.__name__,
+            repr((u"".join(tmp)).lstrip(u"|")).lstrip(u"u"),
+            self.methods is not None and u" (%s)" % u", ".join(self.methods) or u"",
+            self.endpoint,
+        )
+
+
+class BaseConverter(object):
+    """Base class for all converters."""
+
+    regex = "[^/]+"
+    weight = 100
+
+    def __init__(self, map):
+        self.map = map
+
+    def to_python(self, value):
+        return value
+
+    def to_url(self, value):
+        if isinstance(value, (bytes, bytearray)):
+            return _fast_url_quote(value)
+        return _fast_url_quote(text_type(value).encode(self.map.charset))
+
+
+class UnicodeConverter(BaseConverter):
+    """This converter is the default converter and accepts any string but
+    only one path segment.  Thus the string can not include a slash.
+
+    This is the default validator.
+
+    Example::
+
+        Rule('/pages/<page>'),
+        Rule('/<string(length=2):lang_code>')
+
+    :param map: the :class:`Map`.
+    :param minlength: the minimum length of the string.  Must be greater
+                      or equal 1.
+    :param maxlength: the maximum length of the string.
+    :param length: the exact length of the string.
+    """
+
+    def __init__(self, map, minlength=1, maxlength=None, length=None):
+        BaseConverter.__init__(self, map)
+        if length is not None:
+            length = "{%d}" % int(length)
+        else:
+            if maxlength is None:
+                maxlength = ""
+            else:
+                maxlength = int(maxlength)
+            length = "{%s,%s}" % (int(minlength), maxlength)
+        self.regex = "[^/]" + length
+
+
+class AnyConverter(BaseConverter):
+    """Matches one of the items provided.  Items can either be Python
+    identifiers or strings::
+
+        Rule('/<any(about, help, imprint, class, "foo,bar"):page_name>')
+
+    :param map: the :class:`Map`.
+    :param items: this function accepts the possible items as positional
+                  arguments.
+    """
+
+    def __init__(self, map, *items):
+        BaseConverter.__init__(self, map)
+        self.regex = "(?:%s)" % "|".join([re.escape(x) for x in items])
+
+
+class PathConverter(BaseConverter):
+    """Like the default :class:`UnicodeConverter`, but it also matches
+    slashes.  This is useful for wikis and similar applications::
+
+        Rule('/<path:wikipage>')
+        Rule('/<path:wikipage>/edit')
+
+    :param map: the :class:`Map`.
+    """
+
+    regex = "[^/].*?"
+    weight = 200
+
+
+class NumberConverter(BaseConverter):
+    """Baseclass for `IntegerConverter` and `FloatConverter`.
+
+    :internal:
+    """
+
+    weight = 50
+
+    def __init__(self, map, fixed_digits=0, min=None, max=None, signed=False):
+        if signed:
+            self.regex = self.signed_regex
+        BaseConverter.__init__(self, map)
+        self.fixed_digits = fixed_digits
+        self.min = min
+        self.max = max
+        self.signed = signed
+
+    def to_python(self, value):
+        if self.fixed_digits and len(value) != self.fixed_digits:
+            raise ValidationError()
+        value = self.num_convert(value)
+        if (self.min is not None and value < self.min) or (
+            self.max is not None and value > self.max
+        ):
+            raise ValidationError()
+        return value
+
+    def to_url(self, value):
+        value = self.num_convert(value)
+        if self.fixed_digits:
+            value = ("%%0%sd" % self.fixed_digits) % value
+        return str(value)
+
+    @property
+    def signed_regex(self):
+        return r"-?" + self.regex
+
+
+class IntegerConverter(NumberConverter):
+    """This converter only accepts integer values::
+
+        Rule("/page/<int:page>")
+
+    By default it only accepts unsigned, positive values. The ``signed``
+    parameter will enable signed, negative values. ::
+
+        Rule("/page/<int(signed=True):page>")
+
+    :param map: The :class:`Map`.
+    :param fixed_digits: The number of fixed digits in the URL. If you
+        set this to ``4`` for example, the rule will only match if the
+        URL looks like ``/0001/``. The default is variable length.
+    :param min: The minimal value.
+    :param max: The maximal value.
+    :param signed: Allow signed (negative) values.
+
+    .. versionadded:: 0.15
+        The ``signed`` parameter.
+    """
+
+    regex = r"\d+"
+    num_convert = int
+
+
+class FloatConverter(NumberConverter):
+    """This converter only accepts floating point values::
+
+        Rule("/probability/<float:probability>")
+
+    By default it only accepts unsigned, positive values. The ``signed``
+    parameter will enable signed, negative values. ::
+
+        Rule("/offset/<float(signed=True):offset>")
+
+    :param map: The :class:`Map`.
+    :param min: The minimal value.
+    :param max: The maximal value.
+    :param signed: Allow signed (negative) values.
+
+    .. versionadded:: 0.15
+        The ``signed`` parameter.
+    """
+
+    regex = r"\d+\.\d+"
+    num_convert = float
+
+    def __init__(self, map, min=None, max=None, signed=False):
+        NumberConverter.__init__(self, map, min=min, max=max, signed=signed)
+
+
+class UUIDConverter(BaseConverter):
+    """This converter only accepts UUID strings::
+
+        Rule('/object/<uuid:identifier>')
+
+    .. versionadded:: 0.10
+
+    :param map: the :class:`Map`.
+    """
+
+    regex = (
+        r"[A-Fa-f0-9]{8}-[A-Fa-f0-9]{4}-"
+        r"[A-Fa-f0-9]{4}-[A-Fa-f0-9]{4}-[A-Fa-f0-9]{12}"
+    )
+
+    def to_python(self, value):
+        return uuid.UUID(value)
+
+    def to_url(self, value):
+        return str(value)
+
+
+#: the default converter mapping for the map.
+DEFAULT_CONVERTERS = {
+    "default": UnicodeConverter,
+    "string": UnicodeConverter,
+    "any": AnyConverter,
+    "path": PathConverter,
+    "int": IntegerConverter,
+    "float": FloatConverter,
+    "uuid": UUIDConverter,
+}
+
+
+class Map(object):
+    """The map class stores all the URL rules and some configuration
+    parameters.  Some of the configuration values are only stored on the
+    `Map` instance since those affect all rules, others are just defaults
+    and can be overridden for each rule.  Note that you have to specify all
+    arguments besides the `rules` as keyword arguments!
+
+    :param rules: sequence of url rules for this map.
+    :param default_subdomain: The default subdomain for rules without a
+                              subdomain defined.
+    :param charset: charset of the url. defaults to ``"utf-8"``
+    :param strict_slashes: Take care of trailing slashes.
+    :param redirect_defaults: This will redirect to the default rule if it
+                              wasn't visited that way. This helps creating
+                              unique URLs.
+    :param converters: A dict of converters that adds additional converters
+                       to the list of converters. If you redefine one
+                       converter this will override the original one.
+    :param sort_parameters: If set to `True` the url parameters are sorted.
+                            See `url_encode` for more details.
+    :param sort_key: The sort key function for `url_encode`.
+    :param encoding_errors: the error method to use for decoding
+    :param host_matching: if set to `True` it enables the host matching
+                          feature and disables the subdomain one.  If
+                          enabled the `host` parameter to rules is used
+                          instead of the `subdomain` one.
+
+    .. versionadded:: 0.5
+        `sort_parameters` and `sort_key` was added.
+
+    .. versionadded:: 0.7
+        `encoding_errors` and `host_matching` was added.
+    """
+
+    #: A dict of default converters to be used.
+    default_converters = ImmutableDict(DEFAULT_CONVERTERS)
+
+    def __init__(
+        self,
+        rules=None,
+        default_subdomain="",
+        charset="utf-8",
+        strict_slashes=True,
+        redirect_defaults=True,
+        converters=None,
+        sort_parameters=False,
+        sort_key=None,
+        encoding_errors="replace",
+        host_matching=False,
+    ):
+        self._rules = []
+        self._rules_by_endpoint = {}
+        self._remap = True
+        self._remap_lock = Lock()
+
+        self.default_subdomain = default_subdomain
+        self.charset = charset
+        self.encoding_errors = encoding_errors
+        self.strict_slashes = strict_slashes
+        self.redirect_defaults = redirect_defaults
+        self.host_matching = host_matching
+
+        self.converters = self.default_converters.copy()
+        if converters:
+            self.converters.update(converters)
+
+        self.sort_parameters = sort_parameters
+        self.sort_key = sort_key
+
+        for rulefactory in rules or ():
+            self.add(rulefactory)
+
+    def is_endpoint_expecting(self, endpoint, *arguments):
+        """Iterate over all rules and check if the endpoint expects
+        the arguments provided.  This is for example useful if you have
+        some URLs that expect a language code and others that do not and
+        you want to wrap the builder a bit so that the current language
+        code is automatically added if not provided but endpoints expect
+        it.
+
+        :param endpoint: the endpoint to check.
+        :param arguments: this function accepts one or more arguments
+                          as positional arguments.  Each one of them is
+                          checked.
+        """
+        self.update()
+        arguments = set(arguments)
+        for rule in self._rules_by_endpoint[endpoint]:
+            if arguments.issubset(rule.arguments):
+                return True
+        return False
+
+    def iter_rules(self, endpoint=None):
+        """Iterate over all rules or the rules of an endpoint.
+
+        :param endpoint: if provided only the rules for that endpoint
+                         are returned.
+        :return: an iterator
+        """
+        self.update()
+        if endpoint is not None:
+            return iter(self._rules_by_endpoint[endpoint])
+        return iter(self._rules)
+
+    def add(self, rulefactory):
+        """Add a new rule or factory to the map and bind it.  Requires that the
+        rule is not bound to another map.
+
+        :param rulefactory: a :class:`Rule` or :class:`RuleFactory`
+        """
+        for rule in rulefactory.get_rules(self):
+            rule.bind(self)
+            self._rules.append(rule)
+            self._rules_by_endpoint.setdefault(rule.endpoint, []).append(rule)
+        self._remap = True
+
+    def bind(
+        self,
+        server_name,
+        script_name=None,
+        subdomain=None,
+        url_scheme="http",
+        default_method="GET",
+        path_info=None,
+        query_args=None,
+    ):
+        """Return a new :class:`MapAdapter` with the details specified to the
+        call.  Note that `script_name` will default to ``'/'`` if not further
+        specified or `None`.  The `server_name` at least is a requirement
+        because the HTTP RFC requires absolute URLs for redirects and so all
+        redirect exceptions raised by Werkzeug will contain the full canonical
+        URL.
+
+        If no path_info is passed to :meth:`match` it will use the default path
+        info passed to bind.  While this doesn't really make sense for
+        manual bind calls, it's useful if you bind a map to a WSGI
+        environment which already contains the path info.
+
+        `subdomain` will default to the `default_subdomain` for this map if
+        no defined. If there is no `default_subdomain` you cannot use the
+        subdomain feature.
+
+        .. versionadded:: 0.7
+           `query_args` added
+
+        .. versionadded:: 0.8
+           `query_args` can now also be a string.
+
+        .. versionchanged:: 0.15
+            ``path_info`` defaults to ``'/'`` if ``None``.
+        """
+        server_name = server_name.lower()
+        if self.host_matching:
+            if subdomain is not None:
+                raise RuntimeError("host matching enabled and a subdomain was provided")
+        elif subdomain is None:
+            subdomain = self.default_subdomain
+        if script_name is None:
+            script_name = "/"
+        if path_info is None:
+            path_info = "/"
+        try:
+            server_name = _encode_idna(server_name)
+        except UnicodeError:
+            raise BadHost()
+        return MapAdapter(
+            self,
+            server_name,
+            script_name,
+            subdomain,
+            url_scheme,
+            path_info,
+            default_method,
+            query_args,
+        )
+
+    def bind_to_environ(self, environ, server_name=None, subdomain=None):
+        """Like :meth:`bind` but you can pass it an WSGI environment and it
+        will fetch the information from that dictionary.  Note that because of
+        limitations in the protocol there is no way to get the current
+        subdomain and real `server_name` from the environment.  If you don't
+        provide it, Werkzeug will use `SERVER_NAME` and `SERVER_PORT` (or
+        `HTTP_HOST` if provided) as used `server_name` with disabled subdomain
+        feature.
+
+        If `subdomain` is `None` but an environment and a server name is
+        provided it will calculate the current subdomain automatically.
+        Example: `server_name` is ``'example.com'`` and the `SERVER_NAME`
+        in the wsgi `environ` is ``'staging.dev.example.com'`` the calculated
+        subdomain will be ``'staging.dev'``.
+
+        If the object passed as environ has an environ attribute, the value of
+        this attribute is used instead.  This allows you to pass request
+        objects.  Additionally `PATH_INFO` added as a default of the
+        :class:`MapAdapter` so that you don't have to pass the path info to
+        the match method.
+
+        .. versionchanged:: 0.5
+            previously this method accepted a bogus `calculate_subdomain`
+            parameter that did not have any effect.  It was removed because
+            of that.
+
+        .. versionchanged:: 0.8
+           This will no longer raise a ValueError when an unexpected server
+           name was passed.
+
+        :param environ: a WSGI environment.
+        :param server_name: an optional server name hint (see above).
+        :param subdomain: optionally the current subdomain (see above).
+        """
+        environ = _get_environ(environ)
+
+        wsgi_server_name = get_host(environ).lower()
+
+        if server_name is None:
+            server_name = wsgi_server_name
+        else:
+            server_name = server_name.lower()
+
+        if subdomain is None and not self.host_matching:
+            cur_server_name = wsgi_server_name.split(".")
+            real_server_name = server_name.split(".")
+            offset = -len(real_server_name)
+            if cur_server_name[offset:] != real_server_name:
+                # This can happen even with valid configs if the server was
+                # accesssed directly by IP address under some situations.
+                # Instead of raising an exception like in Werkzeug 0.7 or
+                # earlier we go by an invalid subdomain which will result
+                # in a 404 error on matching.
+                subdomain = "<invalid>"
+            else:
+                subdomain = ".".join(filter(None, cur_server_name[:offset]))
+
+        def _get_wsgi_string(name):
+            val = environ.get(name)
+            if val is not None:
+                return wsgi_decoding_dance(val, self.charset)
+
+        script_name = _get_wsgi_string("SCRIPT_NAME")
+        path_info = _get_wsgi_string("PATH_INFO")
+        query_args = _get_wsgi_string("QUERY_STRING")
+        return Map.bind(
+            self,
+            server_name,
+            script_name,
+            subdomain,
+            environ["wsgi.url_scheme"],
+            environ["REQUEST_METHOD"],
+            path_info,
+            query_args=query_args,
+        )
+
+    def update(self):
+        """Called before matching and building to keep the compiled rules
+        in the correct order after things changed.
+        """
+        if not self._remap:
+            return
+
+        with self._remap_lock:
+            if not self._remap:
+                return
+
+            self._rules.sort(key=lambda x: x.match_compare_key())
+            for rules in itervalues(self._rules_by_endpoint):
+                rules.sort(key=lambda x: x.build_compare_key())
+            self._remap = False
+
+    def __repr__(self):
+        rules = self.iter_rules()
+        return "%s(%s)" % (self.__class__.__name__, pformat(list(rules)))
+
+
+class MapAdapter(object):
+
+    """Returned by :meth:`Map.bind` or :meth:`Map.bind_to_environ` and does
+    the URL matching and building based on runtime information.
+    """
+
+    def __init__(
+        self,
+        map,
+        server_name,
+        script_name,
+        subdomain,
+        url_scheme,
+        path_info,
+        default_method,
+        query_args=None,
+    ):
+        self.map = map
+        self.server_name = to_unicode(server_name)
+        script_name = to_unicode(script_name)
+        if not script_name.endswith(u"/"):
+            script_name += u"/"
+        self.script_name = script_name
+        self.subdomain = to_unicode(subdomain)
+        self.url_scheme = to_unicode(url_scheme)
+        self.path_info = to_unicode(path_info)
+        self.default_method = to_unicode(default_method)
+        self.query_args = query_args
+
+    def dispatch(
+        self, view_func, path_info=None, method=None, catch_http_exceptions=False
+    ):
+        """Does the complete dispatching process.  `view_func` is called with
+        the endpoint and a dict with the values for the view.  It should
+        look up the view function, call it, and return a response object
+        or WSGI application.  http exceptions are not caught by default
+        so that applications can display nicer error messages by just
+        catching them by hand.  If you want to stick with the default
+        error messages you can pass it ``catch_http_exceptions=True`` and
+        it will catch the http exceptions.
+
+        Here a small example for the dispatch usage::
+
+            from werkzeug.wrappers import Request, Response
+            from werkzeug.wsgi import responder
+            from werkzeug.routing import Map, Rule
+
+            def on_index(request):
+                return Response('Hello from the index')
+
+            url_map = Map([Rule('/', endpoint='index')])
+            views = {'index': on_index}
+
+            @responder
+            def application(environ, start_response):
+                request = Request(environ)
+                urls = url_map.bind_to_environ(environ)
+                return urls.dispatch(lambda e, v: views[e](request, **v),
+                                     catch_http_exceptions=True)
+
+        Keep in mind that this method might return exception objects, too, so
+        use :class:`Response.force_type` to get a response object.
+
+        :param view_func: a function that is called with the endpoint as
+                          first argument and the value dict as second.  Has
+                          to dispatch to the actual view function with this
+                          information.  (see above)
+        :param path_info: the path info to use for matching.  Overrides the
+                          path info specified on binding.
+        :param method: the HTTP method used for matching.  Overrides the
+                       method specified on binding.
+        :param catch_http_exceptions: set to `True` to catch any of the
+                                      werkzeug :class:`HTTPException`\\s.
+        """
+        try:
+            try:
+                endpoint, args = self.match(path_info, method)
+            except RequestRedirect as e:
+                return e
+            return view_func(endpoint, args)
+        except HTTPException as e:
+            if catch_http_exceptions:
+                return e
+            raise
+
+    def match(self, path_info=None, method=None, return_rule=False, query_args=None):
+        """The usage is simple: you just pass the match method the current
+        path info as well as the method (which defaults to `GET`).  The
+        following things can then happen:
+
+        - you receive a `NotFound` exception that indicates that no URL is
+          matching.  A `NotFound` exception is also a WSGI application you
+          can call to get a default page not found page (happens to be the
+          same object as `werkzeug.exceptions.NotFound`)
+
+        - you receive a `MethodNotAllowed` exception that indicates that there
+          is a match for this URL but not for the current request method.
+          This is useful for RESTful applications.
+
+        - you receive a `RequestRedirect` exception with a `new_url`
+          attribute.  This exception is used to notify you about a request
+          Werkzeug requests from your WSGI application.  This is for example the
+          case if you request ``/foo`` although the correct URL is ``/foo/``
+          You can use the `RequestRedirect` instance as response-like object
+          similar to all other subclasses of `HTTPException`.
+
+        - you get a tuple in the form ``(endpoint, arguments)`` if there is
+          a match (unless `return_rule` is True, in which case you get a tuple
+          in the form ``(rule, arguments)``)
+
+        If the path info is not passed to the match method the default path
+        info of the map is used (defaults to the root URL if not defined
+        explicitly).
+
+        All of the exceptions raised are subclasses of `HTTPException` so they
+        can be used as WSGI responses. They will all render generic error or
+        redirect pages.
+
+        Here is a small example for matching:
+
+        >>> m = Map([
+        ...     Rule('/', endpoint='index'),
+        ...     Rule('/downloads/', endpoint='downloads/index'),
+        ...     Rule('/downloads/<int:id>', endpoint='downloads/show')
+        ... ])
+        >>> urls = m.bind("example.com", "/")
+        >>> urls.match("/", "GET")
+        ('index', {})
+        >>> urls.match("/downloads/42")
+        ('downloads/show', {'id': 42})
+
+        And here is what happens on redirect and missing URLs:
+
+        >>> urls.match("/downloads")
+        Traceback (most recent call last):
+          ...
+        RequestRedirect: http://example.com/downloads/
+        >>> urls.match("/missing")
+        Traceback (most recent call last):
+          ...
+        NotFound: 404 Not Found
+
+        :param path_info: the path info to use for matching.  Overrides the
+                          path info specified on binding.
+        :param method: the HTTP method used for matching.  Overrides the
+                       method specified on binding.
+        :param return_rule: return the rule that matched instead of just the
+                            endpoint (defaults to `False`).
+        :param query_args: optional query arguments that are used for
+                           automatic redirects as string or dictionary.  It's
+                           currently not possible to use the query arguments
+                           for URL matching.
+
+        .. versionadded:: 0.6
+           `return_rule` was added.
+
+        .. versionadded:: 0.7
+           `query_args` was added.
+
+        .. versionchanged:: 0.8
+           `query_args` can now also be a string.
+        """
+        self.map.update()
+        if path_info is None:
+            path_info = self.path_info
+        else:
+            path_info = to_unicode(path_info, self.map.charset)
+        if query_args is None:
+            query_args = self.query_args
+        method = (method or self.default_method).upper()
+
+        path = u"%s|%s" % (
+            self.map.host_matching and self.server_name or self.subdomain,
+            path_info and "/%s" % path_info.lstrip("/"),
+        )
+
+        have_match_for = set()
+        for rule in self.map._rules:
+            try:
+                rv = rule.match(path, method)
+            except RequestSlash:
+                raise RequestRedirect(
+                    self.make_redirect_url(
+                        url_quote(path_info, self.map.charset, safe="/:|+") + "/",
+                        query_args,
+                    )
+                )
+            except RequestAliasRedirect as e:
+                raise RequestRedirect(
+                    self.make_alias_redirect_url(
+                        path, rule.endpoint, e.matched_values, method, query_args
+                    )
+                )
+            if rv is None:
+                continue
+            if rule.methods is not None and method not in rule.methods:
+                have_match_for.update(rule.methods)
+                continue
+
+            if self.map.redirect_defaults:
+                redirect_url = self.get_default_redirect(rule, method, rv, query_args)
+                if redirect_url is not None:
+                    raise RequestRedirect(redirect_url)
+
+            if rule.redirect_to is not None:
+                if isinstance(rule.redirect_to, string_types):
+
+                    def _handle_match(match):
+                        value = rv[match.group(1)]
+                        return rule._converters[match.group(1)].to_url(value)
+
+                    redirect_url = _simple_rule_re.sub(_handle_match, rule.redirect_to)
+                else:
+                    redirect_url = rule.redirect_to(self, **rv)
+                raise RequestRedirect(
+                    str(
+                        url_join(
+                            "%s://%s%s%s"
+                            % (
+                                self.url_scheme or "http",
+                                self.subdomain + "." if self.subdomain else "",
+                                self.server_name,
+                                self.script_name,
+                            ),
+                            redirect_url,
+                        )
+                    )
+                )
+
+            if return_rule:
+                return rule, rv
+            else:
+                return rule.endpoint, rv
+
+        if have_match_for:
+            raise MethodNotAllowed(valid_methods=list(have_match_for))
+        raise NotFound()
+
+    def test(self, path_info=None, method=None):
+        """Test if a rule would match.  Works like `match` but returns `True`
+        if the URL matches, or `False` if it does not exist.
+
+        :param path_info: the path info to use for matching.  Overrides the
+                          path info specified on binding.
+        :param method: the HTTP method used for matching.  Overrides the
+                       method specified on binding.
+        """
+        try:
+            self.match(path_info, method)
+        except RequestRedirect:
+            pass
+        except HTTPException:
+            return False
+        return True
+
+    def allowed_methods(self, path_info=None):
+        """Returns the valid methods that match for a given path.
+
+        .. versionadded:: 0.7
+        """
+        try:
+            self.match(path_info, method="--")
+        except MethodNotAllowed as e:
+            return e.valid_methods
+        except HTTPException:
+            pass
+        return []
+
+    def get_host(self, domain_part):
+        """Figures out the full host name for the given domain part.  The
+        domain part is a subdomain in case host matching is disabled or
+        a full host name.
+        """
+        if self.map.host_matching:
+            if domain_part is None:
+                return self.server_name
+            return to_unicode(domain_part, "ascii")
+        subdomain = domain_part
+        if subdomain is None:
+            subdomain = self.subdomain
+        else:
+            subdomain = to_unicode(subdomain, "ascii")
+        return (subdomain + u"." if subdomain else u"") + self.server_name
+
+    def get_default_redirect(self, rule, method, values, query_args):
+        """A helper that returns the URL to redirect to if it finds one.
+        This is used for default redirecting only.
+
+        :internal:
+        """
+        assert self.map.redirect_defaults
+        for r in self.map._rules_by_endpoint[rule.endpoint]:
+            # every rule that comes after this one, including ourself
+            # has a lower priority for the defaults.  We order the ones
+            # with the highest priority up for building.
+            if r is rule:
+                break
+            if r.provides_defaults_for(rule) and r.suitable_for(values, method):
+                values.update(r.defaults)
+                domain_part, path = r.build(values)
+                return self.make_redirect_url(path, query_args, domain_part=domain_part)
+
+    def encode_query_args(self, query_args):
+        if not isinstance(query_args, string_types):
+            query_args = url_encode(query_args, self.map.charset)
+        return query_args
+
+    def make_redirect_url(self, path_info, query_args=None, domain_part=None):
+        """Creates a redirect URL.
+
+        :internal:
+        """
+        suffix = ""
+        if query_args:
+            suffix = "?" + self.encode_query_args(query_args)
+        return str(
+            "%s://%s/%s%s"
+            % (
+                self.url_scheme or "http",
+                self.get_host(domain_part),
+                posixpath.join(
+                    self.script_name[:-1].lstrip("/"), path_info.lstrip("/")
+                ),
+                suffix,
+            )
+        )
+
+    def make_alias_redirect_url(self, path, endpoint, values, method, query_args):
+        """Internally called to make an alias redirect URL."""
+        url = self.build(
+            endpoint, values, method, append_unknown=False, force_external=True
+        )
+        if query_args:
+            url += "?" + self.encode_query_args(query_args)
+        assert url != path, "detected invalid alias setting. No canonical URL found"
+        return url
+
+    def _partial_build(self, endpoint, values, method, append_unknown):
+        """Helper for :meth:`build`.  Returns subdomain and path for the
+        rule that accepts this endpoint, values and method.
+
+        :internal:
+        """
+        # in case the method is none, try with the default method first
+        if method is None:
+            rv = self._partial_build(
+                endpoint, values, self.default_method, append_unknown
+            )
+            if rv is not None:
+                return rv
+
+        # default method did not match or a specific method is passed,
+        # check all and go with first result.
+        for rule in self.map._rules_by_endpoint.get(endpoint, ()):
+            if rule.suitable_for(values, method):
+                rv = rule.build(values, append_unknown)
+                if rv is not None:
+                    return rv
+
+    def build(
+        self,
+        endpoint,
+        values=None,
+        method=None,
+        force_external=False,
+        append_unknown=True,
+    ):
+        """Building URLs works pretty much the other way round.  Instead of
+        `match` you call `build` and pass it the endpoint and a dict of
+        arguments for the placeholders.
+
+        The `build` function also accepts an argument called `force_external`
+        which, if you set it to `True` will force external URLs. Per default
+        external URLs (include the server name) will only be used if the
+        target URL is on a different subdomain.
+
+        >>> m = Map([
+        ...     Rule('/', endpoint='index'),
+        ...     Rule('/downloads/', endpoint='downloads/index'),
+        ...     Rule('/downloads/<int:id>', endpoint='downloads/show')
+        ... ])
+        >>> urls = m.bind("example.com", "/")
+        >>> urls.build("index", {})
+        '/'
+        >>> urls.build("downloads/show", {'id': 42})
+        '/downloads/42'
+        >>> urls.build("downloads/show", {'id': 42}, force_external=True)
+        'http://example.com/downloads/42'
+
+        Because URLs cannot contain non ASCII data you will always get
+        bytestrings back.  Non ASCII characters are urlencoded with the
+        charset defined on the map instance.
+
+        Additional values are converted to unicode and appended to the URL as
+        URL querystring parameters:
+
+        >>> urls.build("index", {'q': 'My Searchstring'})
+        '/?q=My+Searchstring'
+
+        When processing those additional values, lists are furthermore
+        interpreted as multiple values (as per
+        :py:class:`werkzeug.datastructures.MultiDict`):
+
+        >>> urls.build("index", {'q': ['a', 'b', 'c']})
+        '/?q=a&q=b&q=c'
+
+        Passing a ``MultiDict`` will also add multiple values:
+
+        >>> urls.build("index", MultiDict((('p', 'z'), ('q', 'a'), ('q', 'b'))))
+        '/?p=z&q=a&q=b'
+
+        If a rule does not exist when building a `BuildError` exception is
+        raised.
+
+        The build method accepts an argument called `method` which allows you
+        to specify the method you want to have an URL built for if you have
+        different methods for the same endpoint specified.
+
+        .. versionadded:: 0.6
+           the `append_unknown` parameter was added.
+
+        :param endpoint: the endpoint of the URL to build.
+        :param values: the values for the URL to build.  Unhandled values are
+                       appended to the URL as query parameters.
+        :param method: the HTTP method for the rule if there are different
+                       URLs for different methods on the same endpoint.
+        :param force_external: enforce full canonical external URLs. If the URL
+                               scheme is not provided, this will generate
+                               a protocol-relative URL.
+        :param append_unknown: unknown parameters are appended to the generated
+                               URL as query string argument.  Disable this
+                               if you want the builder to ignore those.
+        """
+        self.map.update()
+
+        if values:
+            if isinstance(values, MultiDict):
+                temp_values = {}
+                # iteritems(dict, values) is like `values.lists()`
+                # without the call or `list()` coercion overhead.
+                for key, value in iteritems(dict, values):
+                    if not value:
+                        continue
+                    if len(value) == 1:  # flatten single item lists
+                        value = value[0]
+                        if value is None:  # drop None
+                            continue
+                    temp_values[key] = value
+                values = temp_values
+            else:
+                # drop None
+                values = dict(i for i in iteritems(values) if i[1] is not None)
+        else:
+            values = {}
+
+        rv = self._partial_build(endpoint, values, method, append_unknown)
+        if rv is None:
+            raise BuildError(endpoint, values, method, self)
+        domain_part, path = rv
+
+        host = self.get_host(domain_part)
+
+        # shortcut this.
+        if not force_external and (
+            (self.map.host_matching and host == self.server_name)
+            or (not self.map.host_matching and domain_part == self.subdomain)
+        ):
+            return "%s/%s" % (self.script_name.rstrip("/"), path.lstrip("/"))
+        return str(
+            "%s//%s%s/%s"
+            % (
+                self.url_scheme + ":" if self.url_scheme else "",
+                host,
+                self.script_name[:-1],
+                path.lstrip("/"),
+            )
+        )
diff --git a/python/werkzeug/security.py b/python/werkzeug/security.py
new file mode 100644
index 0000000..1842afd
--- /dev/null
+++ b/python/werkzeug/security.py
@@ -0,0 +1,241 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.security
+    ~~~~~~~~~~~~~~~~~
+
+    Security related helpers such as secure password hashing tools.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import hashlib
+import hmac
+import os
+import posixpath
+from random import SystemRandom
+from struct import Struct
+
+from ._compat import izip
+from ._compat import PY2
+from ._compat import range_type
+from ._compat import text_type
+from ._compat import to_bytes
+from ._compat import to_native
+
+SALT_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+DEFAULT_PBKDF2_ITERATIONS = 150000
+
+_pack_int = Struct(">I").pack
+_builtin_safe_str_cmp = getattr(hmac, "compare_digest", None)
+_sys_rng = SystemRandom()
+_os_alt_seps = list(
+    sep for sep in [os.path.sep, os.path.altsep] if sep not in (None, "/")
+)
+
+
+def pbkdf2_hex(
+    data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS, keylen=None, hashfunc=None
+):
+    """Like :func:`pbkdf2_bin`, but returns a hex-encoded string.
+
+    .. versionadded:: 0.9
+
+    :param data: the data to derive.
+    :param salt: the salt for the derivation.
+    :param iterations: the number of iterations.
+    :param keylen: the length of the resulting key.  If not provided,
+                   the digest size will be used.
+    :param hashfunc: the hash function to use.  This can either be the
+                     string name of a known hash function, or a function
+                     from the hashlib module.  Defaults to sha256.
+    """
+    rv = pbkdf2_bin(data, salt, iterations, keylen, hashfunc)
+    return to_native(codecs.encode(rv, "hex_codec"))
+
+
+def pbkdf2_bin(
+    data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS, keylen=None, hashfunc=None
+):
+    """Returns a binary digest for the PBKDF2 hash algorithm of `data`
+    with the given `salt`. It iterates `iterations` times and produces a
+    key of `keylen` bytes. By default, SHA-256 is used as hash function;
+    a different hashlib `hashfunc` can be provided.
+
+    .. versionadded:: 0.9
+
+    :param data: the data to derive.
+    :param salt: the salt for the derivation.
+    :param iterations: the number of iterations.
+    :param keylen: the length of the resulting key.  If not provided
+                   the digest size will be used.
+    :param hashfunc: the hash function to use.  This can either be the
+                     string name of a known hash function or a function
+                     from the hashlib module.  Defaults to sha256.
+    """
+    if not hashfunc:
+        hashfunc = "sha256"
+
+    data = to_bytes(data)
+    salt = to_bytes(salt)
+
+    if callable(hashfunc):
+        _test_hash = hashfunc()
+        hash_name = getattr(_test_hash, "name", None)
+    else:
+        hash_name = hashfunc
+    return hashlib.pbkdf2_hmac(hash_name, data, salt, iterations, keylen)
+
+
+def safe_str_cmp(a, b):
+    """This function compares strings in somewhat constant time.  This
+    requires that the length of at least one string is known in advance.
+
+    Returns `True` if the two strings are equal, or `False` if they are not.
+
+    .. versionadded:: 0.7
+    """
+    if isinstance(a, text_type):
+        a = a.encode("utf-8")
+    if isinstance(b, text_type):
+        b = b.encode("utf-8")
+
+    if _builtin_safe_str_cmp is not None:
+        return _builtin_safe_str_cmp(a, b)
+
+    if len(a) != len(b):
+        return False
+
+    rv = 0
+    if PY2:
+        for x, y in izip(a, b):
+            rv |= ord(x) ^ ord(y)
+    else:
+        for x, y in izip(a, b):
+            rv |= x ^ y
+
+    return rv == 0
+
+
+def gen_salt(length):
+    """Generate a random string of SALT_CHARS with specified ``length``."""
+    if length <= 0:
+        raise ValueError("Salt length must be positive")
+    return "".join(_sys_rng.choice(SALT_CHARS) for _ in range_type(length))
+
+
+def _hash_internal(method, salt, password):
+    """Internal password hash helper.  Supports plaintext without salt,
+    unsalted and salted passwords.  In case salted passwords are used
+    hmac is used.
+    """
+    if method == "plain":
+        return password, method
+
+    if isinstance(password, text_type):
+        password = password.encode("utf-8")
+
+    if method.startswith("pbkdf2:"):
+        args = method[7:].split(":")
+        if len(args) not in (1, 2):
+            raise ValueError("Invalid number of arguments for PBKDF2")
+        method = args.pop(0)
+        iterations = args and int(args[0] or 0) or DEFAULT_PBKDF2_ITERATIONS
+        is_pbkdf2 = True
+        actual_method = "pbkdf2:%s:%d" % (method, iterations)
+    else:
+        is_pbkdf2 = False
+        actual_method = method
+
+    if is_pbkdf2:
+        if not salt:
+            raise ValueError("Salt is required for PBKDF2")
+        rv = pbkdf2_hex(password, salt, iterations, hashfunc=method)
+    elif salt:
+        if isinstance(salt, text_type):
+            salt = salt.encode("utf-8")
+        mac = _create_mac(salt, password, method)
+        rv = mac.hexdigest()
+    else:
+        rv = hashlib.new(method, password).hexdigest()
+    return rv, actual_method
+
+
+def _create_mac(key, msg, method):
+    if callable(method):
+        return hmac.HMAC(key, msg, method)
+
+    def hashfunc(d=b""):
+        return hashlib.new(method, d)
+
+    # Python 2.7 used ``hasattr(digestmod, '__call__')``
+    # to detect if hashfunc is callable
+    hashfunc.__call__ = hashfunc
+    return hmac.HMAC(key, msg, hashfunc)
+
+
+def generate_password_hash(password, method="pbkdf2:sha256", salt_length=8):
+    """Hash a password with the given method and salt with a string of
+    the given length. The format of the string returned includes the method
+    that was used so that :func:`check_password_hash` can check the hash.
+
+    The format for the hashed string looks like this::
+
+        method$salt$hash
+
+    This method can **not** generate unsalted passwords but it is possible
+    to set param method='plain' in order to enforce plaintext passwords.
+    If a salt is used, hmac is used internally to salt the password.
+
+    If PBKDF2 is wanted it can be enabled by setting the method to
+    ``pbkdf2:method:iterations`` where iterations is optional::
+
+        pbkdf2:sha256:80000$salt$hash
+        pbkdf2:sha256$salt$hash
+
+    :param password: the password to hash.
+    :param method: the hash method to use (one that hashlib supports). Can
+                   optionally be in the format ``pbkdf2:<method>[:iterations]``
+                   to enable PBKDF2.
+    :param salt_length: the length of the salt in letters.
+    """
+    salt = gen_salt(salt_length) if method != "plain" else ""
+    h, actual_method = _hash_internal(method, salt, password)
+    return "%s$%s$%s" % (actual_method, salt, h)
+
+
+def check_password_hash(pwhash, password):
+    """check a password against a given salted and hashed password value.
+    In order to support unsalted legacy passwords this method supports
+    plain text passwords, md5 and sha1 hashes (both salted and unsalted).
+
+    Returns `True` if the password matched, `False` otherwise.
+
+    :param pwhash: a hashed string like returned by
+                   :func:`generate_password_hash`.
+    :param password: the plaintext password to compare against the hash.
+    """
+    if pwhash.count("$") < 2:
+        return False
+    method, salt, hashval = pwhash.split("$", 2)
+    return safe_str_cmp(_hash_internal(method, salt, password)[0], hashval)
+
+
+def safe_join(directory, *pathnames):
+    """Safely join `directory` and one or more untrusted `pathnames`.  If this
+    cannot be done, this function returns ``None``.
+
+    :param directory: the base directory.
+    :param pathnames: the untrusted pathnames relative to that directory.
+    """
+    parts = [directory]
+    for filename in pathnames:
+        if filename != "":
+            filename = posixpath.normpath(filename)
+        for sep in _os_alt_seps:
+            if sep in filename:
+                return None
+        if os.path.isabs(filename) or filename == ".." or filename.startswith("../"):
+            return None
+        parts.append(filename)
+    return posixpath.join(*parts)
diff --git a/python/werkzeug/serving.py b/python/werkzeug/serving.py
new file mode 100644
index 0000000..ff9f880
--- /dev/null
+++ b/python/werkzeug/serving.py
@@ -0,0 +1,1074 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.serving
+    ~~~~~~~~~~~~~~~~
+
+    There are many ways to serve a WSGI application.  While you're developing
+    it you usually don't want a full blown webserver like Apache but a simple
+    standalone one.  From Python 2.5 onwards there is the `wsgiref`_ server in
+    the standard library.  If you're using older versions of Python you can
+    download the package from the cheeseshop.
+
+    However there are some caveats. Sourcecode won't reload itself when
+    changed and each time you kill the server using ``^C`` you get an
+    `KeyboardInterrupt` error.  While the latter is easy to solve the first
+    one can be a pain in the ass in some situations.
+
+    The easiest way is creating a small ``start-myproject.py`` that runs the
+    application::
+
+        #!/usr/bin/env python
+        # -*- coding: utf-8 -*-
+        from myproject import make_app
+        from werkzeug.serving import run_simple
+
+        app = make_app(...)
+        run_simple('localhost', 8080, app, use_reloader=True)
+
+    You can also pass it a `extra_files` keyword argument with a list of
+    additional files (like configuration files) you want to observe.
+
+    For bigger applications you should consider using `click`
+    (http://click.pocoo.org) instead of a simple start file.
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import io
+import os
+import signal
+import socket
+import sys
+
+import werkzeug
+from ._compat import PY2
+from ._compat import reraise
+from ._compat import WIN
+from ._compat import wsgi_encoding_dance
+from ._internal import _log
+from .exceptions import InternalServerError
+from .urls import uri_to_iri
+from .urls import url_parse
+from .urls import url_unquote
+
+try:
+    import socketserver
+    from http.server import BaseHTTPRequestHandler
+    from http.server import HTTPServer
+except ImportError:
+    import SocketServer as socketserver
+    from BaseHTTPServer import HTTPServer
+    from BaseHTTPServer import BaseHTTPRequestHandler
+
+try:
+    import ssl
+except ImportError:
+
+    class _SslDummy(object):
+        def __getattr__(self, name):
+            raise RuntimeError("SSL support unavailable")
+
+    ssl = _SslDummy()
+
+try:
+    import termcolor
+except ImportError:
+    termcolor = None
+
+
+def _get_openssl_crypto_module():
+    try:
+        from OpenSSL import crypto
+    except ImportError:
+        raise TypeError("Using ad-hoc certificates requires the pyOpenSSL library.")
+    else:
+        return crypto
+
+
+ThreadingMixIn = socketserver.ThreadingMixIn
+can_fork = hasattr(os, "fork")
+
+if can_fork:
+    ForkingMixIn = socketserver.ForkingMixIn
+else:
+
+    class ForkingMixIn(object):
+        pass
+
+
+try:
+    af_unix = socket.AF_UNIX
+except AttributeError:
+    af_unix = None
+
+
+LISTEN_QUEUE = 128
+can_open_by_fd = not WIN and hasattr(socket, "fromfd")
+
+# On Python 3, ConnectionError represents the same errnos as
+# socket.error from Python 2, while socket.error is an alias for the
+# more generic OSError.
+if PY2:
+    _ConnectionError = socket.error
+else:
+    _ConnectionError = ConnectionError
+
+
+class DechunkedInput(io.RawIOBase):
+    """An input stream that handles Transfer-Encoding 'chunked'"""
+
+    def __init__(self, rfile):
+        self._rfile = rfile
+        self._done = False
+        self._len = 0
+
+    def readable(self):
+        return True
+
+    def read_chunk_len(self):
+        try:
+            line = self._rfile.readline().decode("latin1")
+            _len = int(line.strip(), 16)
+        except ValueError:
+            raise IOError("Invalid chunk header")
+        if _len < 0:
+            raise IOError("Negative chunk length not allowed")
+        return _len
+
+    def readinto(self, buf):
+        read = 0
+        while not self._done and read < len(buf):
+            if self._len == 0:
+                # This is the first chunk or we fully consumed the previous
+                # one. Read the next length of the next chunk
+                self._len = self.read_chunk_len()
+
+            if self._len == 0:
+                # Found the final chunk of size 0. The stream is now exhausted,
+                # but there is still a final newline that should be consumed
+                self._done = True
+
+            if self._len > 0:
+                # There is data (left) in this chunk, so append it to the
+                # buffer. If this operation fully consumes the chunk, this will
+                # reset self._len to 0.
+                n = min(len(buf), self._len)
+                buf[read : read + n] = self._rfile.read(n)
+                self._len -= n
+                read += n
+
+            if self._len == 0:
+                # Skip the terminating newline of a chunk that has been fully
+                # consumed. This also applies to the 0-sized final chunk
+                terminator = self._rfile.readline()
+                if terminator not in (b"\n", b"\r\n", b"\r"):
+                    raise IOError("Missing chunk terminating newline")
+
+        return read
+
+
+class WSGIRequestHandler(BaseHTTPRequestHandler, object):
+
+    """A request handler that implements WSGI dispatching."""
+
+    @property
+    def server_version(self):
+        return "Werkzeug/" + werkzeug.__version__
+
+    def make_environ(self):
+        request_url = url_parse(self.path)
+
+        def shutdown_server():
+            self.server.shutdown_signal = True
+
+        url_scheme = "http" if self.server.ssl_context is None else "https"
+        if not self.client_address:
+            self.client_address = "<local>"
+        if isinstance(self.client_address, str):
+            self.client_address = (self.client_address, 0)
+        else:
+            pass
+        path_info = url_unquote(request_url.path)
+
+        environ = {
+            "wsgi.version": (1, 0),
+            "wsgi.url_scheme": url_scheme,
+            "wsgi.input": self.rfile,
+            "wsgi.errors": sys.stderr,
+            "wsgi.multithread": self.server.multithread,
+            "wsgi.multiprocess": self.server.multiprocess,
+            "wsgi.run_once": False,
+            "werkzeug.server.shutdown": shutdown_server,
+            "SERVER_SOFTWARE": self.server_version,
+            "REQUEST_METHOD": self.command,
+            "SCRIPT_NAME": "",
+            "PATH_INFO": wsgi_encoding_dance(path_info),
+            "QUERY_STRING": wsgi_encoding_dance(request_url.query),
+            # Non-standard, added by mod_wsgi, uWSGI
+            "REQUEST_URI": wsgi_encoding_dance(self.path),
+            # Non-standard, added by gunicorn
+            "RAW_URI": wsgi_encoding_dance(self.path),
+            "REMOTE_ADDR": self.address_string(),
+            "REMOTE_PORT": self.port_integer(),
+            "SERVER_NAME": self.server.server_address[0],
+            "SERVER_PORT": str(self.server.server_address[1]),
+            "SERVER_PROTOCOL": self.request_version,
+        }
+
+        for key, value in self.get_header_items():
+            key = key.upper().replace("-", "_")
+            value = value.replace("\r\n", "")
+            if key not in ("CONTENT_TYPE", "CONTENT_LENGTH"):
+                key = "HTTP_" + key
+                if key in environ:
+                    value = "{},{}".format(environ[key], value)
+            environ[key] = value
+
+        if environ.get("HTTP_TRANSFER_ENCODING", "").strip().lower() == "chunked":
+            environ["wsgi.input_terminated"] = True
+            environ["wsgi.input"] = DechunkedInput(environ["wsgi.input"])
+
+        if request_url.scheme and request_url.netloc:
+            environ["HTTP_HOST"] = request_url.netloc
+
+        return environ
+
+    def run_wsgi(self):
+        if self.headers.get("Expect", "").lower().strip() == "100-continue":
+            self.wfile.write(b"HTTP/1.1 100 Continue\r\n\r\n")
+
+        self.environ = environ = self.make_environ()
+        headers_set = []
+        headers_sent = []
+
+        def write(data):
+            assert headers_set, "write() before start_response"
+            if not headers_sent:
+                status, response_headers = headers_sent[:] = headers_set
+                try:
+                    code, msg = status.split(None, 1)
+                except ValueError:
+                    code, msg = status, ""
+                code = int(code)
+                self.send_response(code, msg)
+                header_keys = set()
+                for key, value in response_headers:
+                    self.send_header(key, value)
+                    key = key.lower()
+                    header_keys.add(key)
+                if not (
+                    "content-length" in header_keys
+                    or environ["REQUEST_METHOD"] == "HEAD"
+                    or code < 200
+                    or code in (204, 304)
+                ):
+                    self.close_connection = True
+                    self.send_header("Connection", "close")
+                if "server" not in header_keys:
+                    self.send_header("Server", self.version_string())
+                if "date" not in header_keys:
+                    self.send_header("Date", self.date_time_string())
+                self.end_headers()
+
+            assert isinstance(data, bytes), "applications must write bytes"
+            self.wfile.write(data)
+            self.wfile.flush()
+
+        def start_response(status, response_headers, exc_info=None):
+            if exc_info:
+                try:
+                    if headers_sent:
+                        reraise(*exc_info)
+                finally:
+                    exc_info = None
+            elif headers_set:
+                raise AssertionError("Headers already set")
+            headers_set[:] = [status, response_headers]
+            return write
+
+        def execute(app):
+            application_iter = app(environ, start_response)
+            try:
+                for data in application_iter:
+                    write(data)
+                if not headers_sent:
+                    write(b"")
+            finally:
+                if hasattr(application_iter, "close"):
+                    application_iter.close()
+                application_iter = None
+
+        try:
+            execute(self.server.app)
+        except (_ConnectionError, socket.timeout) as e:
+            self.connection_dropped(e, environ)
+        except Exception:
+            if self.server.passthrough_errors:
+                raise
+            from .debug.tbtools import get_current_traceback
+
+            traceback = get_current_traceback(ignore_system_exceptions=True)
+            try:
+                # if we haven't yet sent the headers but they are set
+                # we roll back to be able to set them again.
+                if not headers_sent:
+                    del headers_set[:]
+                execute(InternalServerError())
+            except Exception:
+                pass
+            self.server.log("error", "Error on request:\n%s", traceback.plaintext)
+
+    def handle(self):
+        """Handles a request ignoring dropped connections."""
+        rv = None
+        try:
+            rv = BaseHTTPRequestHandler.handle(self)
+        except (_ConnectionError, socket.timeout) as e:
+            self.connection_dropped(e)
+        except Exception as e:
+            if self.server.ssl_context is None or not is_ssl_error(e):
+                raise
+        if self.server.shutdown_signal:
+            self.initiate_shutdown()
+        return rv
+
+    def initiate_shutdown(self):
+        """A horrible, horrible way to kill the server for Python 2.6 and
+        later.  It's the best we can do.
+        """
+        # Windows does not provide SIGKILL, go with SIGTERM then.
+        sig = getattr(signal, "SIGKILL", signal.SIGTERM)
+        # reloader active
+        if is_running_from_reloader():
+            os.kill(os.getpid(), sig)
+        # python 2.7
+        self.server._BaseServer__shutdown_request = True
+        # python 2.6
+        self.server._BaseServer__serving = False
+
+    def connection_dropped(self, error, environ=None):
+        """Called if the connection was closed by the client.  By default
+        nothing happens.
+        """
+
+    def handle_one_request(self):
+        """Handle a single HTTP request."""
+        self.raw_requestline = self.rfile.readline()
+        if not self.raw_requestline:
+            self.close_connection = 1
+        elif self.parse_request():
+            return self.run_wsgi()
+
+    def send_response(self, code, message=None):
+        """Send the response header and log the response code."""
+        self.log_request(code)
+        if message is None:
+            message = code in self.responses and self.responses[code][0] or ""
+        if self.request_version != "HTTP/0.9":
+            hdr = "%s %d %s\r\n" % (self.protocol_version, code, message)
+            self.wfile.write(hdr.encode("ascii"))
+
+    def version_string(self):
+        return BaseHTTPRequestHandler.version_string(self).strip()
+
+    def address_string(self):
+        if getattr(self, "environ", None):
+            return self.environ["REMOTE_ADDR"]
+        elif not self.client_address:
+            return "<local>"
+        elif isinstance(self.client_address, str):
+            return self.client_address
+        else:
+            return self.client_address[0]
+
+    def port_integer(self):
+        return self.client_address[1]
+
+    def log_request(self, code="-", size="-"):
+        try:
+            path = uri_to_iri(self.path)
+            msg = "%s %s %s" % (self.command, path, self.request_version)
+        except AttributeError:
+            # path isn't set if the requestline was bad
+            msg = self.requestline
+
+        code = str(code)
+
+        if termcolor:
+            color = termcolor.colored
+
+            if code[0] == "1":  # 1xx - Informational
+                msg = color(msg, attrs=["bold"])
+            elif code[0] == "2":  # 2xx - Success
+                msg = color(msg, color="white")
+            elif code == "304":  # 304 - Resource Not Modified
+                msg = color(msg, color="cyan")
+            elif code[0] == "3":  # 3xx - Redirection
+                msg = color(msg, color="green")
+            elif code == "404":  # 404 - Resource Not Found
+                msg = color(msg, color="yellow")
+            elif code[0] == "4":  # 4xx - Client Error
+                msg = color(msg, color="red", attrs=["bold"])
+            else:  # 5xx, or any other response
+                msg = color(msg, color="magenta", attrs=["bold"])
+
+        self.log("info", '"%s" %s %s', msg, code, size)
+
+    def log_error(self, *args):
+        self.log("error", *args)
+
+    def log_message(self, format, *args):
+        self.log("info", format, *args)
+
+    def log(self, type, message, *args):
+        _log(
+            type,
+            "%s - - [%s] %s\n"
+            % (self.address_string(), self.log_date_time_string(), message % args),
+        )
+
+    def get_header_items(self):
+        """
+        Get an iterable list of key/value pairs representing headers.
+
+        This function provides Python 2/3 compatibility as related to the
+        parsing of request headers. Python 2.7 is not compliant with
+        RFC 3875 Section 4.1.18 which requires multiple values for headers
+        to be provided or RFC 2616 which allows for folding of multi-line
+        headers. This function will return a matching list regardless
+        of Python version. It can be removed once Python 2.7 support
+        is dropped.
+
+        :return: List of tuples containing header hey/value pairs
+        """
+        if PY2:
+            # For Python 2, process the headers manually according to
+            # W3C RFC 2616 Section 4.2.
+            items = []
+            for header in self.headers.headers:
+                # Remove "\r\n" from the header and split on ":" to get
+                # the field name and value.
+                try:
+                    key, value = header[0:-2].split(":", 1)
+                except ValueError:
+                    # If header could not be slit with : but starts with white
+                    # space and it follows an existing header, it's a folded
+                    # header.
+                    if header[0] in ("\t", " ") and items:
+                        # Pop off the last header
+                        key, value = items.pop()
+                        # Append the current header to the value of the last
+                        # header which will be placed back on the end of the
+                        # list
+                        value = value + header
+                    # Otherwise it's just a bad header and should error
+                    else:
+                        # Re-raise the value error
+                        raise
+
+                # Add the key and the value once stripped of leading
+                # white space. The specification allows for stripping
+                # trailing white space but the Python 3 code does not
+                # strip trailing white space. Therefore, trailing space
+                # will be left as is to match the Python 3 behavior.
+                items.append((key, value.lstrip()))
+        else:
+            items = self.headers.items()
+
+        return items
+
+
+#: backwards compatible name if someone is subclassing it
+BaseRequestHandler = WSGIRequestHandler
+
+
+def generate_adhoc_ssl_pair(cn=None):
+    from random import random
+
+    crypto = _get_openssl_crypto_module()
+
+    # pretty damn sure that this is not actually accepted by anyone
+    if cn is None:
+        cn = "*"
+
+    cert = crypto.X509()
+    cert.set_serial_number(int(random() * sys.maxsize))
+    cert.gmtime_adj_notBefore(0)
+    cert.gmtime_adj_notAfter(60 * 60 * 24 * 365)
+
+    subject = cert.get_subject()
+    subject.CN = cn
+    subject.O = "Dummy Certificate"  # noqa: E741
+
+    issuer = cert.get_issuer()
+    issuer.CN = subject.CN
+    issuer.O = subject.O  # noqa: E741
+
+    pkey = crypto.PKey()
+    pkey.generate_key(crypto.TYPE_RSA, 2048)
+    cert.set_pubkey(pkey)
+    cert.sign(pkey, "sha256")
+
+    return cert, pkey
+
+
+def make_ssl_devcert(base_path, host=None, cn=None):
+    """Creates an SSL key for development.  This should be used instead of
+    the ``'adhoc'`` key which generates a new cert on each server start.
+    It accepts a path for where it should store the key and cert and
+    either a host or CN.  If a host is given it will use the CN
+    ``*.host/CN=host``.
+
+    For more information see :func:`run_simple`.
+
+    .. versionadded:: 0.9
+
+    :param base_path: the path to the certificate and key.  The extension
+                      ``.crt`` is added for the certificate, ``.key`` is
+                      added for the key.
+    :param host: the name of the host.  This can be used as an alternative
+                 for the `cn`.
+    :param cn: the `CN` to use.
+    """
+    from OpenSSL import crypto
+
+    if host is not None:
+        cn = "*.%s/CN=%s" % (host, host)
+    cert, pkey = generate_adhoc_ssl_pair(cn=cn)
+
+    cert_file = base_path + ".crt"
+    pkey_file = base_path + ".key"
+
+    with open(cert_file, "wb") as f:
+        f.write(crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
+    with open(pkey_file, "wb") as f:
+        f.write(crypto.dump_privatekey(crypto.FILETYPE_PEM, pkey))
+
+    return cert_file, pkey_file
+
+
+def generate_adhoc_ssl_context():
+    """Generates an adhoc SSL context for the development server."""
+    crypto = _get_openssl_crypto_module()
+    import tempfile
+    import atexit
+
+    cert, pkey = generate_adhoc_ssl_pair()
+    cert_handle, cert_file = tempfile.mkstemp()
+    pkey_handle, pkey_file = tempfile.mkstemp()
+    atexit.register(os.remove, pkey_file)
+    atexit.register(os.remove, cert_file)
+
+    os.write(cert_handle, crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
+    os.write(pkey_handle, crypto.dump_privatekey(crypto.FILETYPE_PEM, pkey))
+    os.close(cert_handle)
+    os.close(pkey_handle)
+    ctx = load_ssl_context(cert_file, pkey_file)
+    return ctx
+
+
+def load_ssl_context(cert_file, pkey_file=None, protocol=None):
+    """Loads SSL context from cert/private key files and optional protocol.
+    Many parameters are directly taken from the API of
+    :py:class:`ssl.SSLContext`.
+
+    :param cert_file: Path of the certificate to use.
+    :param pkey_file: Path of the private key to use. If not given, the key
+                      will be obtained from the certificate file.
+    :param protocol: One of the ``PROTOCOL_*`` constants in the stdlib ``ssl``
+                     module. Defaults to ``PROTOCOL_SSLv23``.
+    """
+    if protocol is None:
+        protocol = ssl.PROTOCOL_SSLv23
+    ctx = _SSLContext(protocol)
+    ctx.load_cert_chain(cert_file, pkey_file)
+    return ctx
+
+
+class _SSLContext(object):
+
+    """A dummy class with a small subset of Python3's ``ssl.SSLContext``, only
+    intended to be used with and by Werkzeug."""
+
+    def __init__(self, protocol):
+        self._protocol = protocol
+        self._certfile = None
+        self._keyfile = None
+        self._password = None
+
+    def load_cert_chain(self, certfile, keyfile=None, password=None):
+        self._certfile = certfile
+        self._keyfile = keyfile or certfile
+        self._password = password
+
+    def wrap_socket(self, sock, **kwargs):
+        return ssl.wrap_socket(
+            sock,
+            keyfile=self._keyfile,
+            certfile=self._certfile,
+            ssl_version=self._protocol,
+            **kwargs
+        )
+
+
+def is_ssl_error(error=None):
+    """Checks if the given error (or the current one) is an SSL error."""
+    exc_types = (ssl.SSLError,)
+    try:
+        from OpenSSL.SSL import Error
+
+        exc_types += (Error,)
+    except ImportError:
+        pass
+
+    if error is None:
+        error = sys.exc_info()[1]
+    return isinstance(error, exc_types)
+
+
+def select_address_family(host, port):
+    """Return ``AF_INET4``, ``AF_INET6``, or ``AF_UNIX`` depending on
+    the host and port."""
+    # disabled due to problems with current ipv6 implementations
+    # and various operating systems.  Probably this code also is
+    # not supposed to work, but I can't come up with any other
+    # ways to implement this.
+    # try:
+    #     info = socket.getaddrinfo(host, port, socket.AF_UNSPEC,
+    #                               socket.SOCK_STREAM, 0,
+    #                               socket.AI_PASSIVE)
+    #     if info:
+    #         return info[0][0]
+    # except socket.gaierror:
+    #     pass
+    if host.startswith("unix://"):
+        return socket.AF_UNIX
+    elif ":" in host and hasattr(socket, "AF_INET6"):
+        return socket.AF_INET6
+    return socket.AF_INET
+
+
+def get_sockaddr(host, port, family):
+    """Return a fully qualified socket address that can be passed to
+    :func:`socket.bind`."""
+    if family == af_unix:
+        return host.split("://", 1)[1]
+    try:
+        res = socket.getaddrinfo(
+            host, port, family, socket.SOCK_STREAM, socket.IPPROTO_TCP
+        )
+    except socket.gaierror:
+        return host, port
+    return res[0][4]
+
+
+class BaseWSGIServer(HTTPServer, object):
+
+    """Simple single-threaded, single-process WSGI server."""
+
+    multithread = False
+    multiprocess = False
+    request_queue_size = LISTEN_QUEUE
+
+    def __init__(
+        self,
+        host,
+        port,
+        app,
+        handler=None,
+        passthrough_errors=False,
+        ssl_context=None,
+        fd=None,
+    ):
+        if handler is None:
+            handler = WSGIRequestHandler
+
+        self.address_family = select_address_family(host, port)
+
+        if fd is not None:
+            real_sock = socket.fromfd(fd, self.address_family, socket.SOCK_STREAM)
+            port = 0
+
+        server_address = get_sockaddr(host, int(port), self.address_family)
+
+        # remove socket file if it already exists
+        if self.address_family == af_unix and os.path.exists(server_address):
+            os.unlink(server_address)
+        HTTPServer.__init__(self, server_address, handler)
+
+        self.app = app
+        self.passthrough_errors = passthrough_errors
+        self.shutdown_signal = False
+        self.host = host
+        self.port = self.socket.getsockname()[1]
+
+        # Patch in the original socket.
+        if fd is not None:
+            self.socket.close()
+            self.socket = real_sock
+            self.server_address = self.socket.getsockname()
+
+        if ssl_context is not None:
+            if isinstance(ssl_context, tuple):
+                ssl_context = load_ssl_context(*ssl_context)
+            if ssl_context == "adhoc":
+                ssl_context = generate_adhoc_ssl_context()
+            # If we are on Python 2 the return value from socket.fromfd
+            # is an internal socket object but what we need for ssl wrap
+            # is the wrapper around it :(
+            sock = self.socket
+            if PY2 and not isinstance(sock, socket.socket):
+                sock = socket.socket(sock.family, sock.type, sock.proto, sock)
+            self.socket = ssl_context.wrap_socket(sock, server_side=True)
+            self.ssl_context = ssl_context
+        else:
+            self.ssl_context = None
+
+    def log(self, type, message, *args):
+        _log(type, message, *args)
+
+    def serve_forever(self):
+        self.shutdown_signal = False
+        try:
+            HTTPServer.serve_forever(self)
+        except KeyboardInterrupt:
+            pass
+        finally:
+            self.server_close()
+
+    def handle_error(self, request, client_address):
+        if self.passthrough_errors:
+            raise
+        # Python 2 still causes a socket.error after the earlier
+        # handling, so silence it here.
+        if isinstance(sys.exc_info()[1], _ConnectionError):
+            return
+        return HTTPServer.handle_error(self, request, client_address)
+
+    def get_request(self):
+        con, info = self.socket.accept()
+        return con, info
+
+
+class ThreadedWSGIServer(ThreadingMixIn, BaseWSGIServer):
+
+    """A WSGI server that does threading."""
+
+    multithread = True
+    daemon_threads = True
+
+
+class ForkingWSGIServer(ForkingMixIn, BaseWSGIServer):
+
+    """A WSGI server that does forking."""
+
+    multiprocess = True
+
+    def __init__(
+        self,
+        host,
+        port,
+        app,
+        processes=40,
+        handler=None,
+        passthrough_errors=False,
+        ssl_context=None,
+        fd=None,
+    ):
+        if not can_fork:
+            raise ValueError("Your platform does not support forking.")
+        BaseWSGIServer.__init__(
+            self, host, port, app, handler, passthrough_errors, ssl_context, fd
+        )
+        self.max_children = processes
+
+
+def make_server(
+    host=None,
+    port=None,
+    app=None,
+    threaded=False,
+    processes=1,
+    request_handler=None,
+    passthrough_errors=False,
+    ssl_context=None,
+    fd=None,
+):
+    """Create a new server instance that is either threaded, or forks
+    or just processes one request after another.
+    """
+    if threaded and processes > 1:
+        raise ValueError("cannot have a multithreaded and multi process server.")
+    elif threaded:
+        return ThreadedWSGIServer(
+            host, port, app, request_handler, passthrough_errors, ssl_context, fd=fd
+        )
+    elif processes > 1:
+        return ForkingWSGIServer(
+            host,
+            port,
+            app,
+            processes,
+            request_handler,
+            passthrough_errors,
+            ssl_context,
+            fd=fd,
+        )
+    else:
+        return BaseWSGIServer(
+            host, port, app, request_handler, passthrough_errors, ssl_context, fd=fd
+        )
+
+
+def is_running_from_reloader():
+    """Checks if the application is running from within the Werkzeug
+    reloader subprocess.
+
+    .. versionadded:: 0.10
+    """
+    return os.environ.get("WERKZEUG_RUN_MAIN") == "true"
+
+
+def run_simple(
+    hostname,
+    port,
+    application,
+    use_reloader=False,
+    use_debugger=False,
+    use_evalex=True,
+    extra_files=None,
+    reloader_interval=1,
+    reloader_type="auto",
+    threaded=False,
+    processes=1,
+    request_handler=None,
+    static_files=None,
+    passthrough_errors=False,
+    ssl_context=None,
+):
+    """Start a WSGI application. Optional features include a reloader,
+    multithreading and fork support.
+
+    This function has a command-line interface too::
+
+        python -m werkzeug.serving --help
+
+    .. versionadded:: 0.5
+       `static_files` was added to simplify serving of static files as well
+       as `passthrough_errors`.
+
+    .. versionadded:: 0.6
+       support for SSL was added.
+
+    .. versionadded:: 0.8
+       Added support for automatically loading a SSL context from certificate
+       file and private key.
+
+    .. versionadded:: 0.9
+       Added command-line interface.
+
+    .. versionadded:: 0.10
+       Improved the reloader and added support for changing the backend
+       through the `reloader_type` parameter.  See :ref:`reloader`
+       for more information.
+
+    .. versionchanged:: 0.15
+        Bind to a Unix socket by passing a path that starts with
+        ``unix://`` as the ``hostname``.
+
+    :param hostname: The host to bind to, for example ``'localhost'``.
+        If the value is a path that starts with ``unix://`` it will bind
+        to a Unix socket instead of a TCP socket..
+    :param port: The port for the server.  eg: ``8080``
+    :param application: the WSGI application to execute
+    :param use_reloader: should the server automatically restart the python
+                         process if modules were changed?
+    :param use_debugger: should the werkzeug debugging system be used?
+    :param use_evalex: should the exception evaluation feature be enabled?
+    :param extra_files: a list of files the reloader should watch
+                        additionally to the modules.  For example configuration
+                        files.
+    :param reloader_interval: the interval for the reloader in seconds.
+    :param reloader_type: the type of reloader to use.  The default is
+                          auto detection.  Valid values are ``'stat'`` and
+                          ``'watchdog'``. See :ref:`reloader` for more
+                          information.
+    :param threaded: should the process handle each request in a separate
+                     thread?
+    :param processes: if greater than 1 then handle each request in a new process
+                      up to this maximum number of concurrent processes.
+    :param request_handler: optional parameter that can be used to replace
+                            the default one.  You can use this to replace it
+                            with a different
+                            :class:`~BaseHTTPServer.BaseHTTPRequestHandler`
+                            subclass.
+    :param static_files: a list or dict of paths for static files.  This works
+                         exactly like :class:`SharedDataMiddleware`, it's actually
+                         just wrapping the application in that middleware before
+                         serving.
+    :param passthrough_errors: set this to `True` to disable the error catching.
+                               This means that the server will die on errors but
+                               it can be useful to hook debuggers in (pdb etc.)
+    :param ssl_context: an SSL context for the connection. Either an
+                        :class:`ssl.SSLContext`, a tuple in the form
+                        ``(cert_file, pkey_file)``, the string ``'adhoc'`` if
+                        the server should automatically create one, or ``None``
+                        to disable SSL (which is the default).
+    """
+    if not isinstance(port, int):
+        raise TypeError("port must be an integer")
+    if use_debugger:
+        from .debug import DebuggedApplication
+
+        application = DebuggedApplication(application, use_evalex)
+    if static_files:
+        from .middleware.shared_data import SharedDataMiddleware
+
+        application = SharedDataMiddleware(application, static_files)
+
+    def log_startup(sock):
+        display_hostname = hostname if hostname not in ("", "*") else "localhost"
+        quit_msg = "(Press CTRL+C to quit)"
+        if sock.family == af_unix:
+            _log("info", " * Running on %s %s", display_hostname, quit_msg)
+        else:
+            if ":" in display_hostname:
+                display_hostname = "[%s]" % display_hostname
+            port = sock.getsockname()[1]
+            _log(
+                "info",
+                " * Running on %s://%s:%d/ %s",
+                "http" if ssl_context is None else "https",
+                display_hostname,
+                port,
+                quit_msg,
+            )
+
+    def inner():
+        try:
+            fd = int(os.environ["WERKZEUG_SERVER_FD"])
+        except (LookupError, ValueError):
+            fd = None
+        srv = make_server(
+            hostname,
+            port,
+            application,
+            threaded,
+            processes,
+            request_handler,
+            passthrough_errors,
+            ssl_context,
+            fd=fd,
+        )
+        if fd is None:
+            log_startup(srv.socket)
+        srv.serve_forever()
+
+    if use_reloader:
+        # If we're not running already in the subprocess that is the
+        # reloader we want to open up a socket early to make sure the
+        # port is actually available.
+        if not is_running_from_reloader():
+            if port == 0 and not can_open_by_fd:
+                raise ValueError(
+                    "Cannot bind to a random port with enabled "
+                    "reloader if the Python interpreter does "
+                    "not support socket opening by fd."
+                )
+
+            # Create and destroy a socket so that any exceptions are
+            # raised before we spawn a separate Python interpreter and
+            # lose this ability.
+            address_family = select_address_family(hostname, port)
+            server_address = get_sockaddr(hostname, port, address_family)
+            s = socket.socket(address_family, socket.SOCK_STREAM)
+            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            s.bind(server_address)
+            if hasattr(s, "set_inheritable"):
+                s.set_inheritable(True)
+
+            # If we can open the socket by file descriptor, then we can just
+            # reuse this one and our socket will survive the restarts.
+            if can_open_by_fd:
+                os.environ["WERKZEUG_SERVER_FD"] = str(s.fileno())
+                s.listen(LISTEN_QUEUE)
+                log_startup(s)
+            else:
+                s.close()
+                if address_family == af_unix:
+                    _log("info", "Unlinking %s" % server_address)
+                    os.unlink(server_address)
+
+        # Do not use relative imports, otherwise "python -m werkzeug.serving"
+        # breaks.
+        from ._reloader import run_with_reloader
+
+        run_with_reloader(inner, extra_files, reloader_interval, reloader_type)
+    else:
+        inner()
+
+
+def run_with_reloader(*args, **kwargs):
+    # People keep using undocumented APIs.  Do not use this function
+    # please, we do not guarantee that it continues working.
+    from ._reloader import run_with_reloader
+
+    return run_with_reloader(*args, **kwargs)
+
+
+def main():
+    """A simple command-line interface for :py:func:`run_simple`."""
+
+    # in contrast to argparse, this works at least under Python < 2.7
+    import optparse
+    from .utils import import_string
+
+    parser = optparse.OptionParser(usage="Usage: %prog [options] app_module:app_object")
+    parser.add_option(
+        "-b",
+        "--bind",
+        dest="address",
+        help="The hostname:port the app should listen on.",
+    )
+    parser.add_option(
+        "-d",
+        "--debug",
+        dest="use_debugger",
+        action="store_true",
+        default=False,
+        help="Use Werkzeug's debugger.",
+    )
+    parser.add_option(
+        "-r",
+        "--reload",
+        dest="use_reloader",
+        action="store_true",
+        default=False,
+        help="Reload Python process if modules change.",
+    )
+    options, args = parser.parse_args()
+
+    hostname, port = None, None
+    if options.address:
+        address = options.address.split(":")
+        hostname = address[0]
+        if len(address) > 1:
+            port = address[1]
+
+    if len(args) != 1:
+        sys.stdout.write("No application supplied, or too much. See --help\n")
+        sys.exit(1)
+    app = import_string(args[0])
+
+    run_simple(
+        hostname=(hostname or "127.0.0.1"),
+        port=int(port or 5000),
+        application=app,
+        use_reloader=options.use_reloader,
+        use_debugger=options.use_debugger,
+    )
+
+
+if __name__ == "__main__":
+    main()
diff --git a/python/werkzeug/test.py b/python/werkzeug/test.py
new file mode 100644
index 0000000..6148665
--- /dev/null
+++ b/python/werkzeug/test.py
@@ -0,0 +1,1146 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.test
+    ~~~~~~~~~~~~~
+
+    This module implements a client to WSGI applications for testing.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import mimetypes
+import sys
+from io import BytesIO
+from itertools import chain
+from random import random
+from tempfile import TemporaryFile
+from time import time
+
+from ._compat import iteritems
+from ._compat import iterlists
+from ._compat import itervalues
+from ._compat import make_literal_wrapper
+from ._compat import reraise
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import to_bytes
+from ._compat import wsgi_encoding_dance
+from ._internal import _get_environ
+from .datastructures import CallbackDict
+from .datastructures import CombinedMultiDict
+from .datastructures import EnvironHeaders
+from .datastructures import FileMultiDict
+from .datastructures import FileStorage
+from .datastructures import Headers
+from .datastructures import MultiDict
+from .http import dump_cookie
+from .http import dump_options_header
+from .http import parse_options_header
+from .urls import iri_to_uri
+from .urls import url_encode
+from .urls import url_fix
+from .urls import url_parse
+from .urls import url_unparse
+from .urls import url_unquote
+from .utils import get_content_type
+from .wrappers import BaseRequest
+from .wsgi import ClosingIterator
+from .wsgi import get_current_url
+
+try:
+    from urllib.request import Request as U2Request
+except ImportError:
+    from urllib2 import Request as U2Request
+
+try:
+    from http.cookiejar import CookieJar
+except ImportError:
+    from cookielib import CookieJar
+
+
+def stream_encode_multipart(
+    values, use_tempfile=True, threshold=1024 * 500, boundary=None, charset="utf-8"
+):
+    """Encode a dict of values (either strings or file descriptors or
+    :class:`FileStorage` objects.) into a multipart encoded string stored
+    in a file descriptor.
+    """
+    if boundary is None:
+        boundary = "---------------WerkzeugFormPart_%s%s" % (time(), random())
+    _closure = [BytesIO(), 0, False]
+
+    if use_tempfile:
+
+        def write_binary(string):
+            stream, total_length, on_disk = _closure
+            if on_disk:
+                stream.write(string)
+            else:
+                length = len(string)
+                if length + _closure[1] <= threshold:
+                    stream.write(string)
+                else:
+                    new_stream = TemporaryFile("wb+")
+                    new_stream.write(stream.getvalue())
+                    new_stream.write(string)
+                    _closure[0] = new_stream
+                    _closure[2] = True
+                _closure[1] = total_length + length
+
+    else:
+        write_binary = _closure[0].write
+
+    def write(string):
+        write_binary(string.encode(charset))
+
+    if not isinstance(values, MultiDict):
+        values = MultiDict(values)
+
+    for key, values in iterlists(values):
+        for value in values:
+            write('--%s\r\nContent-Disposition: form-data; name="%s"' % (boundary, key))
+            reader = getattr(value, "read", None)
+            if reader is not None:
+                filename = getattr(value, "filename", getattr(value, "name", None))
+                content_type = getattr(value, "content_type", None)
+                if content_type is None:
+                    content_type = (
+                        filename
+                        and mimetypes.guess_type(filename)[0]
+                        or "application/octet-stream"
+                    )
+                if filename is not None:
+                    write('; filename="%s"\r\n' % filename)
+                else:
+                    write("\r\n")
+                write("Content-Type: %s\r\n\r\n" % content_type)
+                while 1:
+                    chunk = reader(16384)
+                    if not chunk:
+                        break
+                    write_binary(chunk)
+            else:
+                if not isinstance(value, string_types):
+                    value = str(value)
+
+                value = to_bytes(value, charset)
+                write("\r\n\r\n")
+                write_binary(value)
+            write("\r\n")
+    write("--%s--\r\n" % boundary)
+
+    length = int(_closure[0].tell())
+    _closure[0].seek(0)
+    return _closure[0], length, boundary
+
+
+def encode_multipart(values, boundary=None, charset="utf-8"):
+    """Like `stream_encode_multipart` but returns a tuple in the form
+    (``boundary``, ``data``) where data is a bytestring.
+    """
+    stream, length, boundary = stream_encode_multipart(
+        values, use_tempfile=False, boundary=boundary, charset=charset
+    )
+    return boundary, stream.read()
+
+
+def File(fd, filename=None, mimetype=None):
+    """Backwards compat.
+
+    .. deprecated:: 0.5
+    """
+    from warnings import warn
+
+    warn(
+        "'werkzeug.test.File' is deprecated as of version 0.5 and will"
+        " be removed in version 1.0. Use 'EnvironBuilder' or"
+        " 'FileStorage' instead.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return FileStorage(fd, filename=filename, content_type=mimetype)
+
+
+class _TestCookieHeaders(object):
+
+    """A headers adapter for cookielib
+    """
+
+    def __init__(self, headers):
+        self.headers = headers
+
+    def getheaders(self, name):
+        headers = []
+        name = name.lower()
+        for k, v in self.headers:
+            if k.lower() == name:
+                headers.append(v)
+        return headers
+
+    def get_all(self, name, default=None):
+        rv = []
+        for k, v in self.headers:
+            if k.lower() == name.lower():
+                rv.append(v)
+        return rv or default or []
+
+
+class _TestCookieResponse(object):
+
+    """Something that looks like a httplib.HTTPResponse, but is actually just an
+    adapter for our test responses to make them available for cookielib.
+    """
+
+    def __init__(self, headers):
+        self.headers = _TestCookieHeaders(headers)
+
+    def info(self):
+        return self.headers
+
+
+class _TestCookieJar(CookieJar):
+
+    """A cookielib.CookieJar modified to inject and read cookie headers from
+    and to wsgi environments, and wsgi application responses.
+    """
+
+    def inject_wsgi(self, environ):
+        """Inject the cookies as client headers into the server's wsgi
+        environment.
+        """
+        cvals = ["%s=%s" % (c.name, c.value) for c in self]
+
+        if cvals:
+            environ["HTTP_COOKIE"] = "; ".join(cvals)
+        else:
+            environ.pop("HTTP_COOKIE", None)
+
+    def extract_wsgi(self, environ, headers):
+        """Extract the server's set-cookie headers as cookies into the
+        cookie jar.
+        """
+        self.extract_cookies(
+            _TestCookieResponse(headers), U2Request(get_current_url(environ))
+        )
+
+
+def _iter_data(data):
+    """Iterates over a `dict` or :class:`MultiDict` yielding all keys and
+    values.
+    This is used to iterate over the data passed to the
+    :class:`EnvironBuilder`.
+    """
+    if isinstance(data, MultiDict):
+        for key, values in iterlists(data):
+            for value in values:
+                yield key, value
+    else:
+        for key, values in iteritems(data):
+            if isinstance(values, list):
+                for value in values:
+                    yield key, value
+            else:
+                yield key, values
+
+
+class EnvironBuilder(object):
+    """This class can be used to conveniently create a WSGI environment
+    for testing purposes.  It can be used to quickly create WSGI environments
+    or request objects from arbitrary data.
+
+    The signature of this class is also used in some other places as of
+    Werkzeug 0.5 (:func:`create_environ`, :meth:`BaseResponse.from_values`,
+    :meth:`Client.open`).  Because of this most of the functionality is
+    available through the constructor alone.
+
+    Files and regular form data can be manipulated independently of each
+    other with the :attr:`form` and :attr:`files` attributes, but are
+    passed with the same argument to the constructor: `data`.
+
+    `data` can be any of these values:
+
+    -   a `str` or `bytes` object: The object is converted into an
+        :attr:`input_stream`, the :attr:`content_length` is set and you have to
+        provide a :attr:`content_type`.
+    -   a `dict` or :class:`MultiDict`: The keys have to be strings. The values
+        have to be either any of the following objects, or a list of any of the
+        following objects:
+
+        -   a :class:`file`-like object:  These are converted into
+            :class:`FileStorage` objects automatically.
+        -   a `tuple`:  The :meth:`~FileMultiDict.add_file` method is called
+            with the key and the unpacked `tuple` items as positional
+            arguments.
+        -   a `str`:  The string is set as form data for the associated key.
+    -   a file-like object: The object content is loaded in memory and then
+        handled like a regular `str` or a `bytes`.
+
+    :param path: the path of the request.  In the WSGI environment this will
+                 end up as `PATH_INFO`.  If the `query_string` is not defined
+                 and there is a question mark in the `path` everything after
+                 it is used as query string.
+    :param base_url: the base URL is a URL that is used to extract the WSGI
+                     URL scheme, host (server name + server port) and the
+                     script root (`SCRIPT_NAME`).
+    :param query_string: an optional string or dict with URL parameters.
+    :param method: the HTTP method to use, defaults to `GET`.
+    :param input_stream: an optional input stream.  Do not specify this and
+                         `data`.  As soon as an input stream is set you can't
+                         modify :attr:`args` and :attr:`files` unless you
+                         set the :attr:`input_stream` to `None` again.
+    :param content_type: The content type for the request.  As of 0.5 you
+                         don't have to provide this when specifying files
+                         and form data via `data`.
+    :param content_length: The content length for the request.  You don't
+                           have to specify this when providing data via
+                           `data`.
+    :param errors_stream: an optional error stream that is used for
+                          `wsgi.errors`.  Defaults to :data:`stderr`.
+    :param multithread: controls `wsgi.multithread`.  Defaults to `False`.
+    :param multiprocess: controls `wsgi.multiprocess`.  Defaults to `False`.
+    :param run_once: controls `wsgi.run_once`.  Defaults to `False`.
+    :param headers: an optional list or :class:`Headers` object of headers.
+    :param data: a string or dict of form data or a file-object.
+                 See explanation above.
+    :param json: An object to be serialized and assigned to ``data``.
+        Defaults the content type to ``"application/json"``.
+        Serialized with the function assigned to :attr:`json_dumps`.
+    :param environ_base: an optional dict of environment defaults.
+    :param environ_overrides: an optional dict of environment overrides.
+    :param charset: the charset used to encode unicode data.
+
+    .. versionadded:: 0.15
+        The ``json`` param and :meth:`json_dumps` method.
+
+    .. versionadded:: 0.15
+        The environ has keys ``REQUEST_URI`` and ``RAW_URI`` containing
+        the path before perecent-decoding. This is not part of the WSGI
+        PEP, but many WSGI servers include it.
+
+    .. versionchanged:: 0.6
+       ``path`` and ``base_url`` can now be unicode strings that are
+       encoded with :func:`iri_to_uri`.
+    """
+
+    #: the server protocol to use.  defaults to HTTP/1.1
+    server_protocol = "HTTP/1.1"
+
+    #: the wsgi version to use.  defaults to (1, 0)
+    wsgi_version = (1, 0)
+
+    #: the default request class for :meth:`get_request`
+    request_class = BaseRequest
+
+    import json
+
+    #: The serialization function used when ``json`` is passed.
+    json_dumps = staticmethod(json.dumps)
+    del json
+
+    def __init__(
+        self,
+        path="/",
+        base_url=None,
+        query_string=None,
+        method="GET",
+        input_stream=None,
+        content_type=None,
+        content_length=None,
+        errors_stream=None,
+        multithread=False,
+        multiprocess=False,
+        run_once=False,
+        headers=None,
+        data=None,
+        environ_base=None,
+        environ_overrides=None,
+        charset="utf-8",
+        mimetype=None,
+        json=None,
+    ):
+        path_s = make_literal_wrapper(path)
+        if query_string is not None and path_s("?") in path:
+            raise ValueError("Query string is defined in the path and as an argument")
+        if query_string is None and path_s("?") in path:
+            path, query_string = path.split(path_s("?"), 1)
+        self.charset = charset
+        self.path = iri_to_uri(path)
+        if base_url is not None:
+            base_url = url_fix(iri_to_uri(base_url, charset), charset)
+        self.base_url = base_url
+        if isinstance(query_string, (bytes, text_type)):
+            self.query_string = query_string
+        else:
+            if query_string is None:
+                query_string = MultiDict()
+            elif not isinstance(query_string, MultiDict):
+                query_string = MultiDict(query_string)
+            self.args = query_string
+        self.method = method
+        if headers is None:
+            headers = Headers()
+        elif not isinstance(headers, Headers):
+            headers = Headers(headers)
+        self.headers = headers
+        if content_type is not None:
+            self.content_type = content_type
+        if errors_stream is None:
+            errors_stream = sys.stderr
+        self.errors_stream = errors_stream
+        self.multithread = multithread
+        self.multiprocess = multiprocess
+        self.run_once = run_once
+        self.environ_base = environ_base
+        self.environ_overrides = environ_overrides
+        self.input_stream = input_stream
+        self.content_length = content_length
+        self.closed = False
+
+        if json is not None:
+            if data is not None:
+                raise TypeError("can't provide both json and data")
+
+            data = self.json_dumps(json)
+
+            if self.content_type is None:
+                self.content_type = "application/json"
+
+        if data:
+            if input_stream is not None:
+                raise TypeError("can't provide input stream and data")
+            if hasattr(data, "read"):
+                data = data.read()
+            if isinstance(data, text_type):
+                data = data.encode(self.charset)
+            if isinstance(data, bytes):
+                self.input_stream = BytesIO(data)
+                if self.content_length is None:
+                    self.content_length = len(data)
+            else:
+                for key, value in _iter_data(data):
+                    if isinstance(value, (tuple, dict)) or hasattr(value, "read"):
+                        self._add_file_from_data(key, value)
+                    else:
+                        self.form.setlistdefault(key).append(value)
+
+        if mimetype is not None:
+            self.mimetype = mimetype
+
+    @classmethod
+    def from_environ(cls, environ, **kwargs):
+        """Turn an environ dict back into a builder. Any extra kwargs
+        override the args extracted from the environ.
+
+        .. versionadded:: 0.15
+        """
+        headers = Headers(EnvironHeaders(environ))
+        out = {
+            "path": environ["PATH_INFO"],
+            "base_url": cls._make_base_url(
+                environ["wsgi.url_scheme"], headers.pop("Host"), environ["SCRIPT_NAME"]
+            ),
+            "query_string": environ["QUERY_STRING"],
+            "method": environ["REQUEST_METHOD"],
+            "input_stream": environ["wsgi.input"],
+            "content_type": headers.pop("Content-Type", None),
+            "content_length": headers.pop("Content-Length", None),
+            "errors_stream": environ["wsgi.errors"],
+            "multithread": environ["wsgi.multithread"],
+            "multiprocess": environ["wsgi.multiprocess"],
+            "run_once": environ["wsgi.run_once"],
+            "headers": headers,
+        }
+        out.update(kwargs)
+        return cls(**out)
+
+    def _add_file_from_data(self, key, value):
+        """Called in the EnvironBuilder to add files from the data dict."""
+        if isinstance(value, tuple):
+            self.files.add_file(key, *value)
+        elif isinstance(value, dict):
+            from warnings import warn
+
+            warn(
+                "Passing a dict as file data is deprecated as of"
+                " version 0.5 and will be removed in version 1.0. Use"
+                " a tuple or 'FileStorage' object instead.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            value = dict(value)
+            mimetype = value.pop("mimetype", None)
+            if mimetype is not None:
+                value["content_type"] = mimetype
+            self.files.add_file(key, **value)
+        else:
+            self.files.add_file(key, value)
+
+    @staticmethod
+    def _make_base_url(scheme, host, script_root):
+        return url_unparse((scheme, host, script_root, "", "")).rstrip("/") + "/"
+
+    @property
+    def base_url(self):
+        """The base URL is used to extract the URL scheme, host name,
+        port, and root path.
+        """
+        return self._make_base_url(self.url_scheme, self.host, self.script_root)
+
+    @base_url.setter
+    def base_url(self, value):
+        if value is None:
+            scheme = "http"
+            netloc = "localhost"
+            script_root = ""
+        else:
+            scheme, netloc, script_root, qs, anchor = url_parse(value)
+            if qs or anchor:
+                raise ValueError("base url must not contain a query string or fragment")
+        self.script_root = script_root.rstrip("/")
+        self.host = netloc
+        self.url_scheme = scheme
+
+    def _get_content_type(self):
+        ct = self.headers.get("Content-Type")
+        if ct is None and not self._input_stream:
+            if self._files:
+                return "multipart/form-data"
+            elif self._form:
+                return "application/x-www-form-urlencoded"
+            return None
+        return ct
+
+    def _set_content_type(self, value):
+        if value is None:
+            self.headers.pop("Content-Type", None)
+        else:
+            self.headers["Content-Type"] = value
+
+    content_type = property(
+        _get_content_type,
+        _set_content_type,
+        doc="""The content type for the request.  Reflected from and to
+        the :attr:`headers`.  Do not set if you set :attr:`files` or
+        :attr:`form` for auto detection.""",
+    )
+    del _get_content_type, _set_content_type
+
+    def _get_content_length(self):
+        return self.headers.get("Content-Length", type=int)
+
+    def _get_mimetype(self):
+        ct = self.content_type
+        if ct:
+            return ct.split(";")[0].strip()
+
+    def _set_mimetype(self, value):
+        self.content_type = get_content_type(value, self.charset)
+
+    def _get_mimetype_params(self):
+        def on_update(d):
+            self.headers["Content-Type"] = dump_options_header(self.mimetype, d)
+
+        d = parse_options_header(self.headers.get("content-type", ""))[1]
+        return CallbackDict(d, on_update)
+
+    mimetype = property(
+        _get_mimetype,
+        _set_mimetype,
+        doc="""The mimetype (content type without charset etc.)
+
+        .. versionadded:: 0.14
+    """,
+    )
+    mimetype_params = property(
+        _get_mimetype_params,
+        doc=""" The mimetype parameters as dict.  For example if the
+        content type is ``text/html; charset=utf-8`` the params would be
+        ``{'charset': 'utf-8'}``.
+
+        .. versionadded:: 0.14
+        """,
+    )
+    del _get_mimetype, _set_mimetype, _get_mimetype_params
+
+    def _set_content_length(self, value):
+        if value is None:
+            self.headers.pop("Content-Length", None)
+        else:
+            self.headers["Content-Length"] = str(value)
+
+    content_length = property(
+        _get_content_length,
+        _set_content_length,
+        doc="""The content length as integer.  Reflected from and to the
+        :attr:`headers`.  Do not set if you set :attr:`files` or
+        :attr:`form` for auto detection.""",
+    )
+    del _get_content_length, _set_content_length
+
+    def form_property(name, storage, doc):  # noqa: B902
+        key = "_" + name
+
+        def getter(self):
+            if self._input_stream is not None:
+                raise AttributeError("an input stream is defined")
+            rv = getattr(self, key)
+            if rv is None:
+                rv = storage()
+                setattr(self, key, rv)
+
+            return rv
+
+        def setter(self, value):
+            self._input_stream = None
+            setattr(self, key, value)
+
+        return property(getter, setter, doc=doc)
+
+    form = form_property("form", MultiDict, doc="A :class:`MultiDict` of form values.")
+    files = form_property(
+        "files",
+        FileMultiDict,
+        doc="""A :class:`FileMultiDict` of uploaded files.  You can use
+        the :meth:`~FileMultiDict.add_file` method to add new files to
+        the dict.""",
+    )
+    del form_property
+
+    def _get_input_stream(self):
+        return self._input_stream
+
+    def _set_input_stream(self, value):
+        self._input_stream = value
+        self._form = self._files = None
+
+    input_stream = property(
+        _get_input_stream,
+        _set_input_stream,
+        doc="""An optional input stream.  If you set this it will clear
+        :attr:`form` and :attr:`files`.""",
+    )
+    del _get_input_stream, _set_input_stream
+
+    def _get_query_string(self):
+        if self._query_string is None:
+            if self._args is not None:
+                return url_encode(self._args, charset=self.charset)
+            return ""
+        return self._query_string
+
+    def _set_query_string(self, value):
+        self._query_string = value
+        self._args = None
+
+    query_string = property(
+        _get_query_string,
+        _set_query_string,
+        doc="""The query string.  If you set this to a string
+        :attr:`args` will no longer be available.""",
+    )
+    del _get_query_string, _set_query_string
+
+    def _get_args(self):
+        if self._query_string is not None:
+            raise AttributeError("a query string is defined")
+        if self._args is None:
+            self._args = MultiDict()
+        return self._args
+
+    def _set_args(self, value):
+        self._query_string = None
+        self._args = value
+
+    args = property(
+        _get_args, _set_args, doc="The URL arguments as :class:`MultiDict`."
+    )
+    del _get_args, _set_args
+
+    @property
+    def server_name(self):
+        """The server name (read-only, use :attr:`host` to set)"""
+        return self.host.split(":", 1)[0]
+
+    @property
+    def server_port(self):
+        """The server port as integer (read-only, use :attr:`host` to set)"""
+        pieces = self.host.split(":", 1)
+        if len(pieces) == 2 and pieces[1].isdigit():
+            return int(pieces[1])
+        elif self.url_scheme == "https":
+            return 443
+        return 80
+
+    def __del__(self):
+        try:
+            self.close()
+        except Exception:
+            pass
+
+    def close(self):
+        """Closes all files.  If you put real :class:`file` objects into the
+        :attr:`files` dict you can call this method to automatically close
+        them all in one go.
+        """
+        if self.closed:
+            return
+        try:
+            files = itervalues(self.files)
+        except AttributeError:
+            files = ()
+        for f in files:
+            try:
+                f.close()
+            except Exception:
+                pass
+        self.closed = True
+
+    def get_environ(self):
+        """Return the built environ.
+
+        .. versionchanged:: 0.15
+            The content type and length headers are set based on
+            input stream detection. Previously this only set the WSGI
+            keys.
+        """
+        input_stream = self.input_stream
+        content_length = self.content_length
+
+        mimetype = self.mimetype
+        content_type = self.content_type
+
+        if input_stream is not None:
+            start_pos = input_stream.tell()
+            input_stream.seek(0, 2)
+            end_pos = input_stream.tell()
+            input_stream.seek(start_pos)
+            content_length = end_pos - start_pos
+        elif mimetype == "multipart/form-data":
+            values = CombinedMultiDict([self.form, self.files])
+            input_stream, content_length, boundary = stream_encode_multipart(
+                values, charset=self.charset
+            )
+            content_type = mimetype + '; boundary="%s"' % boundary
+        elif mimetype == "application/x-www-form-urlencoded":
+            # XXX: py2v3 review
+            values = url_encode(self.form, charset=self.charset)
+            values = values.encode("ascii")
+            content_length = len(values)
+            input_stream = BytesIO(values)
+        else:
+            input_stream = BytesIO()
+
+        result = {}
+        if self.environ_base:
+            result.update(self.environ_base)
+
+        def _path_encode(x):
+            return wsgi_encoding_dance(url_unquote(x, self.charset), self.charset)
+
+        qs = wsgi_encoding_dance(self.query_string)
+
+        result.update(
+            {
+                "REQUEST_METHOD": self.method,
+                "SCRIPT_NAME": _path_encode(self.script_root),
+                "PATH_INFO": _path_encode(self.path),
+                "QUERY_STRING": qs,
+                # Non-standard, added by mod_wsgi, uWSGI
+                "REQUEST_URI": wsgi_encoding_dance(self.path),
+                # Non-standard, added by gunicorn
+                "RAW_URI": wsgi_encoding_dance(self.path),
+                "SERVER_NAME": self.server_name,
+                "SERVER_PORT": str(self.server_port),
+                "HTTP_HOST": self.host,
+                "SERVER_PROTOCOL": self.server_protocol,
+                "wsgi.version": self.wsgi_version,
+                "wsgi.url_scheme": self.url_scheme,
+                "wsgi.input": input_stream,
+                "wsgi.errors": self.errors_stream,
+                "wsgi.multithread": self.multithread,
+                "wsgi.multiprocess": self.multiprocess,
+                "wsgi.run_once": self.run_once,
+            }
+        )
+
+        headers = self.headers.copy()
+
+        if content_type is not None:
+            result["CONTENT_TYPE"] = content_type
+            headers.set("Content-Type", content_type)
+
+        if content_length is not None:
+            result["CONTENT_LENGTH"] = str(content_length)
+            headers.set("Content-Length", content_length)
+
+        for key, value in headers.to_wsgi_list():
+            result["HTTP_%s" % key.upper().replace("-", "_")] = value
+
+        if self.environ_overrides:
+            result.update(self.environ_overrides)
+
+        return result
+
+    def get_request(self, cls=None):
+        """Returns a request with the data.  If the request class is not
+        specified :attr:`request_class` is used.
+
+        :param cls: The request wrapper to use.
+        """
+        if cls is None:
+            cls = self.request_class
+        return cls(self.get_environ())
+
+
+class ClientRedirectError(Exception):
+    """If a redirect loop is detected when using follow_redirects=True with
+    the :cls:`Client`, then this exception is raised.
+    """
+
+
+class Client(object):
+    """This class allows you to send requests to a wrapped application.
+
+    The response wrapper can be a class or factory function that takes
+    three arguments: app_iter, status and headers.  The default response
+    wrapper just returns a tuple.
+
+    Example::
+
+        class ClientResponse(BaseResponse):
+            ...
+
+        client = Client(MyApplication(), response_wrapper=ClientResponse)
+
+    The use_cookies parameter indicates whether cookies should be stored and
+    sent for subsequent requests. This is True by default, but passing False
+    will disable this behaviour.
+
+    If you want to request some subdomain of your application you may set
+    `allow_subdomain_redirects` to `True` as if not no external redirects
+    are allowed.
+
+    .. versionadded:: 0.5
+       `use_cookies` is new in this version.  Older versions did not provide
+       builtin cookie support.
+
+    .. versionadded:: 0.14
+       The `mimetype` parameter was added.
+
+    .. versionadded:: 0.15
+        The ``json`` parameter.
+    """
+
+    def __init__(
+        self,
+        application,
+        response_wrapper=None,
+        use_cookies=True,
+        allow_subdomain_redirects=False,
+    ):
+        self.application = application
+        self.response_wrapper = response_wrapper
+        if use_cookies:
+            self.cookie_jar = _TestCookieJar()
+        else:
+            self.cookie_jar = None
+        self.allow_subdomain_redirects = allow_subdomain_redirects
+
+    def set_cookie(
+        self,
+        server_name,
+        key,
+        value="",
+        max_age=None,
+        expires=None,
+        path="/",
+        domain=None,
+        secure=None,
+        httponly=False,
+        charset="utf-8",
+    ):
+        """Sets a cookie in the client's cookie jar.  The server name
+        is required and has to match the one that is also passed to
+        the open call.
+        """
+        assert self.cookie_jar is not None, "cookies disabled"
+        header = dump_cookie(
+            key, value, max_age, expires, path, domain, secure, httponly, charset
+        )
+        environ = create_environ(path, base_url="http://" + server_name)
+        headers = [("Set-Cookie", header)]
+        self.cookie_jar.extract_wsgi(environ, headers)
+
+    def delete_cookie(self, server_name, key, path="/", domain=None):
+        """Deletes a cookie in the test client."""
+        self.set_cookie(
+            server_name, key, expires=0, max_age=0, path=path, domain=domain
+        )
+
+    def run_wsgi_app(self, environ, buffered=False):
+        """Runs the wrapped WSGI app with the given environment."""
+        if self.cookie_jar is not None:
+            self.cookie_jar.inject_wsgi(environ)
+        rv = run_wsgi_app(self.application, environ, buffered=buffered)
+        if self.cookie_jar is not None:
+            self.cookie_jar.extract_wsgi(environ, rv[2])
+        return rv
+
+    def resolve_redirect(self, response, new_location, environ, buffered=False):
+        """Perform a new request to the location given by the redirect
+        response to the previous request.
+        """
+        scheme, netloc, path, qs, anchor = url_parse(new_location)
+        builder = EnvironBuilder.from_environ(environ, query_string=qs)
+
+        to_name_parts = netloc.split(":", 1)[0].split(".")
+        from_name_parts = builder.server_name.split(".")
+
+        if to_name_parts != [""]:
+            # The new location has a host, use it for the base URL.
+            builder.url_scheme = scheme
+            builder.host = netloc
+        else:
+            # A local redirect with autocorrect_location_header=False
+            # doesn't have a host, so use the request's host.
+            to_name_parts = from_name_parts
+
+        # Explain why a redirect to a different server name won't be followed.
+        if to_name_parts != from_name_parts:
+            if to_name_parts[-len(from_name_parts) :] == from_name_parts:
+                if not self.allow_subdomain_redirects:
+                    raise RuntimeError("Following subdomain redirects is not enabled.")
+            else:
+                raise RuntimeError("Following external redirects is not supported.")
+
+        path_parts = path.split("/")
+        root_parts = builder.script_root.split("/")
+
+        if path_parts[: len(root_parts)] == root_parts:
+            # Strip the script root from the path.
+            builder.path = path[len(builder.script_root) :]
+        else:
+            # The new location is not under the script root, so use the
+            # whole path and clear the previous root.
+            builder.path = path
+            builder.script_root = ""
+
+        status_code = int(response[1].split(None, 1)[0])
+
+        # Only 307 and 308 preserve all of the original request.
+        if status_code not in {307, 308}:
+            # HEAD is preserved, everything else becomes GET.
+            if builder.method != "HEAD":
+                builder.method = "GET"
+
+            # Clear the body and the headers that describe it.
+            builder.input_stream = None
+            builder.content_type = None
+            builder.content_length = None
+            builder.headers.pop("Transfer-Encoding", None)
+
+        # Disable the response wrapper while handling redirects. Not
+        # thread safe, but the client should not be shared anyway.
+        old_response_wrapper = self.response_wrapper
+        self.response_wrapper = None
+
+        try:
+            return self.open(builder, as_tuple=True, buffered=buffered)
+        finally:
+            self.response_wrapper = old_response_wrapper
+
+    def open(self, *args, **kwargs):
+        """Takes the same arguments as the :class:`EnvironBuilder` class with
+        some additions:  You can provide a :class:`EnvironBuilder` or a WSGI
+        environment as only argument instead of the :class:`EnvironBuilder`
+        arguments and two optional keyword arguments (`as_tuple`, `buffered`)
+        that change the type of the return value or the way the application is
+        executed.
+
+        .. versionchanged:: 0.5
+           If a dict is provided as file in the dict for the `data` parameter
+           the content type has to be called `content_type` now instead of
+           `mimetype`.  This change was made for consistency with
+           :class:`werkzeug.FileWrapper`.
+
+            The `follow_redirects` parameter was added to :func:`open`.
+
+        Additional parameters:
+
+        :param as_tuple: Returns a tuple in the form ``(environ, result)``
+        :param buffered: Set this to True to buffer the application run.
+                         This will automatically close the application for
+                         you as well.
+        :param follow_redirects: Set this to True if the `Client` should
+                                 follow HTTP redirects.
+        """
+        as_tuple = kwargs.pop("as_tuple", False)
+        buffered = kwargs.pop("buffered", False)
+        follow_redirects = kwargs.pop("follow_redirects", False)
+        environ = None
+        if not kwargs and len(args) == 1:
+            if isinstance(args[0], EnvironBuilder):
+                environ = args[0].get_environ()
+            elif isinstance(args[0], dict):
+                environ = args[0]
+        if environ is None:
+            builder = EnvironBuilder(*args, **kwargs)
+            try:
+                environ = builder.get_environ()
+            finally:
+                builder.close()
+
+        response = self.run_wsgi_app(environ.copy(), buffered=buffered)
+
+        # handle redirects
+        redirect_chain = []
+        while 1:
+            status_code = int(response[1].split(None, 1)[0])
+            if (
+                status_code not in {301, 302, 303, 305, 307, 308}
+                or not follow_redirects
+            ):
+                break
+
+            # Exhaust intermediate response bodies to ensure middleware
+            # that returns an iterator runs any cleanup code.
+            if not buffered:
+                for _ in response[0]:
+                    pass
+
+            new_location = response[2]["location"]
+            new_redirect_entry = (new_location, status_code)
+            if new_redirect_entry in redirect_chain:
+                raise ClientRedirectError("loop detected")
+            redirect_chain.append(new_redirect_entry)
+            environ, response = self.resolve_redirect(
+                response, new_location, environ, buffered=buffered
+            )
+
+        if self.response_wrapper is not None:
+            response = self.response_wrapper(*response)
+        if as_tuple:
+            return environ, response
+        return response
+
+    def get(self, *args, **kw):
+        """Like open but method is enforced to GET."""
+        kw["method"] = "GET"
+        return self.open(*args, **kw)
+
+    def patch(self, *args, **kw):
+        """Like open but method is enforced to PATCH."""
+        kw["method"] = "PATCH"
+        return self.open(*args, **kw)
+
+    def post(self, *args, **kw):
+        """Like open but method is enforced to POST."""
+        kw["method"] = "POST"
+        return self.open(*args, **kw)
+
+    def head(self, *args, **kw):
+        """Like open but method is enforced to HEAD."""
+        kw["method"] = "HEAD"
+        return self.open(*args, **kw)
+
+    def put(self, *args, **kw):
+        """Like open but method is enforced to PUT."""
+        kw["method"] = "PUT"
+        return self.open(*args, **kw)
+
+    def delete(self, *args, **kw):
+        """Like open but method is enforced to DELETE."""
+        kw["method"] = "DELETE"
+        return self.open(*args, **kw)
+
+    def options(self, *args, **kw):
+        """Like open but method is enforced to OPTIONS."""
+        kw["method"] = "OPTIONS"
+        return self.open(*args, **kw)
+
+    def trace(self, *args, **kw):
+        """Like open but method is enforced to TRACE."""
+        kw["method"] = "TRACE"
+        return self.open(*args, **kw)
+
+    def __repr__(self):
+        return "<%s %r>" % (self.__class__.__name__, self.application)
+
+
+def create_environ(*args, **kwargs):
+    """Create a new WSGI environ dict based on the values passed.  The first
+    parameter should be the path of the request which defaults to '/'.  The
+    second one can either be an absolute path (in that case the host is
+    localhost:80) or a full path to the request with scheme, netloc port and
+    the path to the script.
+
+    This accepts the same arguments as the :class:`EnvironBuilder`
+    constructor.
+
+    .. versionchanged:: 0.5
+       This function is now a thin wrapper over :class:`EnvironBuilder` which
+       was added in 0.5.  The `headers`, `environ_base`, `environ_overrides`
+       and `charset` parameters were added.
+    """
+    builder = EnvironBuilder(*args, **kwargs)
+    try:
+        return builder.get_environ()
+    finally:
+        builder.close()
+
+
+def run_wsgi_app(app, environ, buffered=False):
+    """Return a tuple in the form (app_iter, status, headers) of the
+    application output.  This works best if you pass it an application that
+    returns an iterator all the time.
+
+    Sometimes applications may use the `write()` callable returned
+    by the `start_response` function.  This tries to resolve such edge
+    cases automatically.  But if you don't get the expected output you
+    should set `buffered` to `True` which enforces buffering.
+
+    If passed an invalid WSGI application the behavior of this function is
+    undefined.  Never pass non-conforming WSGI applications to this function.
+
+    :param app: the application to execute.
+    :param buffered: set to `True` to enforce buffering.
+    :return: tuple in the form ``(app_iter, status, headers)``
+    """
+    environ = _get_environ(environ)
+    response = []
+    buffer = []
+
+    def start_response(status, headers, exc_info=None):
+        if exc_info is not None:
+            reraise(*exc_info)
+        response[:] = [status, headers]
+        return buffer.append
+
+    app_rv = app(environ, start_response)
+    close_func = getattr(app_rv, "close", None)
+    app_iter = iter(app_rv)
+
+    # when buffering we emit the close call early and convert the
+    # application iterator into a regular list
+    if buffered:
+        try:
+            app_iter = list(app_iter)
+        finally:
+            if close_func is not None:
+                close_func()
+
+    # otherwise we iterate the application iter until we have a response, chain
+    # the already received data with the already collected data and wrap it in
+    # a new `ClosingIterator` if we need to restore a `close` callable from the
+    # original return value.
+    else:
+        for item in app_iter:
+            buffer.append(item)
+            if response:
+                break
+        if buffer:
+            app_iter = chain(buffer, app_iter)
+        if close_func is not None and app_iter is not app_rv:
+            app_iter = ClosingIterator(app_iter, close_func)
+
+    return app_iter, response[0], Headers(response[1])
diff --git a/python/werkzeug/testapp.py b/python/werkzeug/testapp.py
new file mode 100644
index 0000000..8ea23be
--- /dev/null
+++ b/python/werkzeug/testapp.py
@@ -0,0 +1,241 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.testapp
+    ~~~~~~~~~~~~~~~~
+
+    Provide a small test application that can be used to test a WSGI server
+    and check it for WSGI compliance.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import base64
+import os
+import sys
+from textwrap import wrap
+
+import werkzeug
+from .utils import escape
+from .wrappers import BaseRequest as Request
+from .wrappers import BaseResponse as Response
+
+logo = Response(
+    base64.b64decode(
+        """
+R0lGODlhoACgAOMIAAEDACwpAEpCAGdgAJaKAM28AOnVAP3rAP/////////
+//////////////////////yH5BAEKAAgALAAAAACgAKAAAAT+EMlJq704680R+F0ojmRpnuj0rWnrv
+nB8rbRs33gu0bzu/0AObxgsGn3D5HHJbCUFyqZ0ukkSDlAidctNFg7gbI9LZlrBaHGtzAae0eloe25
+7w9EDOX2fst/xenyCIn5/gFqDiVVDV4aGeYiKkhSFjnCQY5OTlZaXgZp8nJ2ekaB0SQOjqphrpnOiq
+ncEn65UsLGytLVmQ6m4sQazpbtLqL/HwpnER8bHyLrLOc3Oz8PRONPU1crXN9na263dMt/g4SzjMeX
+m5yDpLqgG7OzJ4u8lT/P69ej3JPn69kHzN2OIAHkB9RUYSFCFQYQJFTIkCDBiwoXWGnowaLEjRm7+G
+p9A7Hhx4rUkAUaSLJlxHMqVMD/aSycSZkyTplCqtGnRAM5NQ1Ly5OmzZc6gO4d6DGAUKA+hSocWYAo
+SlM6oUWX2O/o0KdaVU5vuSQLAa0ADwQgMEMB2AIECZhVSnTno6spgbtXmHcBUrQACcc2FrTrWS8wAf
+78cMFBgwIBgbN+qvTt3ayikRBk7BoyGAGABAdYyfdzRQGV3l4coxrqQ84GpUBmrdR3xNIDUPAKDBSA
+ADIGDhhqTZIWaDcrVX8EsbNzbkvCOxG8bN5w8ly9H8jyTJHC6DFndQydbguh2e/ctZJFXRxMAqqPVA
+tQH5E64SPr1f0zz7sQYjAHg0In+JQ11+N2B0XXBeeYZgBZFx4tqBToiTCPv0YBgQv8JqA6BEf6RhXx
+w1ENhRBnWV8ctEX4Ul2zc3aVGcQNC2KElyTDYyYUWvShdjDyMOGMuFjqnII45aogPhz/CodUHFwaDx
+lTgsaOjNyhGWJQd+lFoAGk8ObghI0kawg+EV5blH3dr+digkYuAGSaQZFHFz2P/cTaLmhF52QeSb45
+Jwxd+uSVGHlqOZpOeJpCFZ5J+rkAkFjQ0N1tah7JJSZUFNsrkeJUJMIBi8jyaEKIhKPomnC91Uo+NB
+yyaJ5umnnpInIFh4t6ZSpGaAVmizqjpByDegYl8tPE0phCYrhcMWSv+uAqHfgH88ak5UXZmlKLVJhd
+dj78s1Fxnzo6yUCrV6rrDOkluG+QzCAUTbCwf9SrmMLzK6p+OPHx7DF+bsfMRq7Ec61Av9i6GLw23r
+idnZ+/OO0a99pbIrJkproCQMA17OPG6suq3cca5ruDfXCCDoS7BEdvmJn5otdqscn+uogRHHXs8cbh
+EIfYaDY1AkrC0cqwcZpnM6ludx72x0p7Fo/hZAcpJDjax0UdHavMKAbiKltMWCF3xxh9k25N/Viud8
+ba78iCvUkt+V6BpwMlErmcgc502x+u1nSxJSJP9Mi52awD1V4yB/QHONsnU3L+A/zR4VL/indx/y64
+gqcj+qgTeweM86f0Qy1QVbvmWH1D9h+alqg254QD8HJXHvjQaGOqEqC22M54PcftZVKVSQG9jhkv7C
+JyTyDoAJfPdu8v7DRZAxsP/ky9MJ3OL36DJfCFPASC3/aXlfLOOON9vGZZHydGf8LnxYJuuVIbl83y
+Az5n/RPz07E+9+zw2A2ahz4HxHo9Kt79HTMx1Q7ma7zAzHgHqYH0SoZWyTuOLMiHwSfZDAQTn0ajk9
+YQqodnUYjByQZhZak9Wu4gYQsMyEpIOAOQKze8CmEF45KuAHTvIDOfHJNipwoHMuGHBnJElUoDmAyX
+c2Qm/R8Ah/iILCCJOEokGowdhDYc/yoL+vpRGwyVSCWFYZNljkhEirGXsalWcAgOdeAdoXcktF2udb
+qbUhjWyMQxYO01o6KYKOr6iK3fE4MaS+DsvBsGOBaMb0Y6IxADaJhFICaOLmiWTlDAnY1KzDG4ambL
+cWBA8mUzjJsN2KjSaSXGqMCVXYpYkj33mcIApyhQf6YqgeNAmNvuC0t4CsDbSshZJkCS1eNisKqlyG
+cF8G2JeiDX6tO6Mv0SmjCa3MFb0bJaGPMU0X7c8XcpvMaOQmCajwSeY9G0WqbBmKv34DsMIEztU6Y2
+KiDlFdt6jnCSqx7Dmt6XnqSKaFFHNO5+FmODxMCWBEaco77lNDGXBM0ECYB/+s7nKFdwSF5hgXumQe
+EZ7amRg39RHy3zIjyRCykQh8Zo2iviRKyTDn/zx6EefptJj2Cw+Ep2FSc01U5ry4KLPYsTyWnVGnvb
+UpyGlhjBUljyjHhWpf8OFaXwhp9O4T1gU9UeyPPa8A2l0p1kNqPXEVRm1AOs1oAGZU596t6SOR2mcB
+Oco1srWtkaVrMUzIErrKri85keKqRQYX9VX0/eAUK1hrSu6HMEX3Qh2sCh0q0D2CtnUqS4hj62sE/z
+aDs2Sg7MBS6xnQeooc2R2tC9YrKpEi9pLXfYXp20tDCpSP8rKlrD4axprb9u1Df5hSbz9QU0cRpfgn
+kiIzwKucd0wsEHlLpe5yHXuc6FrNelOl7pY2+11kTWx7VpRu97dXA3DO1vbkhcb4zyvERYajQgAADs
+="""
+    ),
+    mimetype="image/png",
+)
+
+
+TEMPLATE = u"""\
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+  "http://www.w3.org/TR/html4/loose.dtd">
+<title>WSGI Information</title>
+<style type="text/css">
+  @import url(https://fonts.googleapis.com/css?family=Ubuntu);
+
+  body       { font-family: 'Lucida Grande', 'Lucida Sans Unicode', 'Geneva',
+               'Verdana', sans-serif; background-color: white; color: #000;
+               font-size: 15px; text-align: center; }
+  #logo      { float: right; padding: 0 0 10px 10px; }
+  div.box    { text-align: left; width: 45em; margin: auto; padding: 50px 0;
+               background-color: white; }
+  h1, h2     { font-family: 'Ubuntu', 'Lucida Grande', 'Lucida Sans Unicode',
+               'Geneva', 'Verdana', sans-serif; font-weight: normal; }
+  h1         { margin: 0 0 30px 0; }
+  h2         { font-size: 1.4em; margin: 1em 0 0.5em 0; }
+  table      { width: 100%%; border-collapse: collapse; border: 1px solid #AFC5C9 }
+  table th   { background-color: #AFC1C4; color: white; font-size: 0.72em;
+               font-weight: normal; width: 18em; vertical-align: top;
+               padding: 0.5em 0 0.1em 0.5em; }
+  table td   { border: 1px solid #AFC5C9; padding: 0.1em 0 0.1em 0.5em; }
+  code       { font-family: 'Consolas', 'Monaco', 'Bitstream Vera Sans Mono',
+               monospace; font-size: 0.7em; }
+  ul li      { line-height: 1.5em; }
+  ul.path    { font-size: 0.7em; margin: 0 -30px; padding: 8px 30px;
+               list-style: none; background: #E8EFF0; }
+  ul.path li { line-height: 1.6em; }
+  li.virtual { color: #999; text-decoration: underline; }
+  li.exp     { background: white; }
+</style>
+<div class="box">
+  <img src="?resource=logo" id="logo" alt="[The Werkzeug Logo]" />
+  <h1>WSGI Information</h1>
+  <p>
+    This page displays all available information about the WSGI server and
+    the underlying Python interpreter.
+  <h2 id="python-interpreter">Python Interpreter</h2>
+  <table>
+    <tr>
+      <th>Python Version
+      <td>%(python_version)s
+    <tr>
+      <th>Platform
+      <td>%(platform)s [%(os)s]
+    <tr>
+      <th>API Version
+      <td>%(api_version)s
+    <tr>
+      <th>Byteorder
+      <td>%(byteorder)s
+    <tr>
+      <th>Werkzeug Version
+      <td>%(werkzeug_version)s
+  </table>
+  <h2 id="wsgi-environment">WSGI Environment</h2>
+  <table>%(wsgi_env)s</table>
+  <h2 id="installed-eggs">Installed Eggs</h2>
+  <p>
+    The following python packages were installed on the system as
+    Python eggs:
+  <ul>%(python_eggs)s</ul>
+  <h2 id="sys-path">System Path</h2>
+  <p>
+    The following paths are the current contents of the load path.  The
+    following entries are looked up for Python packages.  Note that not
+    all items in this path are folders.  Gray and underlined items are
+    entries pointing to invalid resources or used by custom import hooks
+    such as the zip importer.
+  <p>
+    Items with a bright background were expanded for display from a relative
+    path.  If you encounter such paths in the output you might want to check
+    your setup as relative paths are usually problematic in multithreaded
+    environments.
+  <ul class="path">%(sys_path)s</ul>
+</div>
+"""
+
+
+def iter_sys_path():
+    if os.name == "posix":
+
+        def strip(x):
+            prefix = os.path.expanduser("~")
+            if x.startswith(prefix):
+                x = "~" + x[len(prefix) :]
+            return x
+
+    else:
+
+        def strip(x):
+            return x
+
+    cwd = os.path.abspath(os.getcwd())
+    for item in sys.path:
+        path = os.path.join(cwd, item or os.path.curdir)
+        yield strip(os.path.normpath(path)), not os.path.isdir(path), path != item
+
+
+def render_testapp(req):
+    try:
+        import pkg_resources
+    except ImportError:
+        eggs = ()
+    else:
+        eggs = sorted(pkg_resources.working_set, key=lambda x: x.project_name.lower())
+    python_eggs = []
+    for egg in eggs:
+        try:
+            version = egg.version
+        except (ValueError, AttributeError):
+            version = "unknown"
+        python_eggs.append(
+            "<li>%s <small>[%s]</small>" % (escape(egg.project_name), escape(version))
+        )
+
+    wsgi_env = []
+    sorted_environ = sorted(req.environ.items(), key=lambda x: repr(x[0]).lower())
+    for key, value in sorted_environ:
+        wsgi_env.append(
+            "<tr><th>%s<td><code>%s</code>"
+            % (escape(str(key)), " ".join(wrap(escape(repr(value)))))
+        )
+
+    sys_path = []
+    for item, virtual, expanded in iter_sys_path():
+        class_ = []
+        if virtual:
+            class_.append("virtual")
+        if expanded:
+            class_.append("exp")
+        sys_path.append(
+            "<li%s>%s"
+            % (' class="%s"' % " ".join(class_) if class_ else "", escape(item))
+        )
+
+    return (
+        TEMPLATE
+        % {
+            "python_version": "<br>".join(escape(sys.version).splitlines()),
+            "platform": escape(sys.platform),
+            "os": escape(os.name),
+            "api_version": sys.api_version,
+            "byteorder": sys.byteorder,
+            "werkzeug_version": werkzeug.__version__,
+            "python_eggs": "\n".join(python_eggs),
+            "wsgi_env": "\n".join(wsgi_env),
+            "sys_path": "\n".join(sys_path),
+        }
+    ).encode("utf-8")
+
+
+def test_app(environ, start_response):
+    """Simple test application that dumps the environment.  You can use
+    it to check if Werkzeug is working properly:
+
+    .. sourcecode:: pycon
+
+        >>> from werkzeug.serving import run_simple
+        >>> from werkzeug.testapp import test_app
+        >>> run_simple('localhost', 3000, test_app)
+         * Running on http://localhost:3000/
+
+    The application displays important information from the WSGI environment,
+    the Python interpreter and the installed libraries.
+    """
+    req = Request(environ, populate_request=False)
+    if req.args.get("resource") == "logo":
+        response = logo
+    else:
+        response = Response(render_testapp(req), mimetype="text/html")
+    return response(environ, start_response)
+
+
+if __name__ == "__main__":
+    from .serving import run_simple
+
+    run_simple("localhost", 5000, test_app, use_reloader=True)
diff --git a/python/werkzeug/urls.py b/python/werkzeug/urls.py
new file mode 100644
index 0000000..38e9e5a
--- /dev/null
+++ b/python/werkzeug/urls.py
@@ -0,0 +1,1134 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.urls
+    ~~~~~~~~~~~~~
+
+    ``werkzeug.urls`` used to provide several wrapper functions for Python 2
+    urlparse, whose main purpose were to work around the behavior of the Py2
+    stdlib and its lack of unicode support. While this was already a somewhat
+    inconvenient situation, it got even more complicated because Python 3's
+    ``urllib.parse`` actually does handle unicode properly. In other words,
+    this module would wrap two libraries with completely different behavior. So
+    now this module contains a 2-and-3-compatible backport of Python 3's
+    ``urllib.parse``, which is mostly API-compatible.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import os
+import re
+from collections import namedtuple
+
+from ._compat import fix_tuple_repr
+from ._compat import implements_to_string
+from ._compat import make_literal_wrapper
+from ._compat import normalize_string_tuple
+from ._compat import PY2
+from ._compat import text_type
+from ._compat import to_native
+from ._compat import to_unicode
+from ._compat import try_coerce_native
+from ._internal import _decode_idna
+from ._internal import _encode_idna
+from .datastructures import iter_multi_items
+from .datastructures import MultiDict
+
+# A regular expression for what a valid schema looks like
+_scheme_re = re.compile(r"^[a-zA-Z0-9+-.]+$")
+
+# Characters that are safe in any part of an URL.
+_always_safe = frozenset(
+    bytearray(
+        b"abcdefghijklmnopqrstuvwxyz"
+        b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        b"0123456789"
+        b"-._~"
+    )
+)
+
+_hexdigits = "0123456789ABCDEFabcdef"
+_hextobyte = dict(
+    ((a + b).encode(), int(a + b, 16)) for a in _hexdigits for b in _hexdigits
+)
+_bytetohex = [("%%%02X" % char).encode("ascii") for char in range(256)]
+
+
+_URLTuple = fix_tuple_repr(
+    namedtuple("_URLTuple", ["scheme", "netloc", "path", "query", "fragment"])
+)
+
+
+class BaseURL(_URLTuple):
+    """Superclass of :py:class:`URL` and :py:class:`BytesURL`."""
+
+    __slots__ = ()
+
+    def replace(self, **kwargs):
+        """Return an URL with the same values, except for those parameters
+        given new values by whichever keyword arguments are specified."""
+        return self._replace(**kwargs)
+
+    @property
+    def host(self):
+        """The host part of the URL if available, otherwise `None`.  The
+        host is either the hostname or the IP address mentioned in the
+        URL.  It will not contain the port.
+        """
+        return self._split_host()[0]
+
+    @property
+    def ascii_host(self):
+        """Works exactly like :attr:`host` but will return a result that
+        is restricted to ASCII.  If it finds a netloc that is not ASCII
+        it will attempt to idna decode it.  This is useful for socket
+        operations when the URL might include internationalized characters.
+        """
+        rv = self.host
+        if rv is not None and isinstance(rv, text_type):
+            try:
+                rv = _encode_idna(rv)
+            except UnicodeError:
+                rv = rv.encode("ascii", "ignore")
+        return to_native(rv, "ascii", "ignore")
+
+    @property
+    def port(self):
+        """The port in the URL as an integer if it was present, `None`
+        otherwise.  This does not fill in default ports.
+        """
+        try:
+            rv = int(to_native(self._split_host()[1]))
+            if 0 <= rv <= 65535:
+                return rv
+        except (ValueError, TypeError):
+            pass
+
+    @property
+    def auth(self):
+        """The authentication part in the URL if available, `None`
+        otherwise.
+        """
+        return self._split_netloc()[0]
+
+    @property
+    def username(self):
+        """The username if it was part of the URL, `None` otherwise.
+        This undergoes URL decoding and will always be a unicode string.
+        """
+        rv = self._split_auth()[0]
+        if rv is not None:
+            return _url_unquote_legacy(rv)
+
+    @property
+    def raw_username(self):
+        """The username if it was part of the URL, `None` otherwise.
+        Unlike :attr:`username` this one is not being decoded.
+        """
+        return self._split_auth()[0]
+
+    @property
+    def password(self):
+        """The password if it was part of the URL, `None` otherwise.
+        This undergoes URL decoding and will always be a unicode string.
+        """
+        rv = self._split_auth()[1]
+        if rv is not None:
+            return _url_unquote_legacy(rv)
+
+    @property
+    def raw_password(self):
+        """The password if it was part of the URL, `None` otherwise.
+        Unlike :attr:`password` this one is not being decoded.
+        """
+        return self._split_auth()[1]
+
+    def decode_query(self, *args, **kwargs):
+        """Decodes the query part of the URL.  Ths is a shortcut for
+        calling :func:`url_decode` on the query argument.  The arguments and
+        keyword arguments are forwarded to :func:`url_decode` unchanged.
+        """
+        return url_decode(self.query, *args, **kwargs)
+
+    def join(self, *args, **kwargs):
+        """Joins this URL with another one.  This is just a convenience
+        function for calling into :meth:`url_join` and then parsing the
+        return value again.
+        """
+        return url_parse(url_join(self, *args, **kwargs))
+
+    def to_url(self):
+        """Returns a URL string or bytes depending on the type of the
+        information stored.  This is just a convenience function
+        for calling :meth:`url_unparse` for this URL.
+        """
+        return url_unparse(self)
+
+    def decode_netloc(self):
+        """Decodes the netloc part into a string."""
+        rv = _decode_idna(self.host or "")
+
+        if ":" in rv:
+            rv = "[%s]" % rv
+        port = self.port
+        if port is not None:
+            rv = "%s:%d" % (rv, port)
+        auth = ":".join(
+            filter(
+                None,
+                [
+                    _url_unquote_legacy(self.raw_username or "", "/:%@"),
+                    _url_unquote_legacy(self.raw_password or "", "/:%@"),
+                ],
+            )
+        )
+        if auth:
+            rv = "%s@%s" % (auth, rv)
+        return rv
+
+    def to_uri_tuple(self):
+        """Returns a :class:`BytesURL` tuple that holds a URI.  This will
+        encode all the information in the URL properly to ASCII using the
+        rules a web browser would follow.
+
+        It's usually more interesting to directly call :meth:`iri_to_uri` which
+        will return a string.
+        """
+        return url_parse(iri_to_uri(self).encode("ascii"))
+
+    def to_iri_tuple(self):
+        """Returns a :class:`URL` tuple that holds a IRI.  This will try
+        to decode as much information as possible in the URL without
+        losing information similar to how a web browser does it for the
+        URL bar.
+
+        It's usually more interesting to directly call :meth:`uri_to_iri` which
+        will return a string.
+        """
+        return url_parse(uri_to_iri(self))
+
+    def get_file_location(self, pathformat=None):
+        """Returns a tuple with the location of the file in the form
+        ``(server, location)``.  If the netloc is empty in the URL or
+        points to localhost, it's represented as ``None``.
+
+        The `pathformat` by default is autodetection but needs to be set
+        when working with URLs of a specific system.  The supported values
+        are ``'windows'`` when working with Windows or DOS paths and
+        ``'posix'`` when working with posix paths.
+
+        If the URL does not point to a local file, the server and location
+        are both represented as ``None``.
+
+        :param pathformat: The expected format of the path component.
+                           Currently ``'windows'`` and ``'posix'`` are
+                           supported.  Defaults to ``None`` which is
+                           autodetect.
+        """
+        if self.scheme != "file":
+            return None, None
+
+        path = url_unquote(self.path)
+        host = self.netloc or None
+
+        if pathformat is None:
+            if os.name == "nt":
+                pathformat = "windows"
+            else:
+                pathformat = "posix"
+
+        if pathformat == "windows":
+            if path[:1] == "/" and path[1:2].isalpha() and path[2:3] in "|:":
+                path = path[1:2] + ":" + path[3:]
+            windows_share = path[:3] in ("\\" * 3, "/" * 3)
+            import ntpath
+
+            path = ntpath.normpath(path)
+            # Windows shared drives are represented as ``\\host\\directory``.
+            # That results in a URL like ``file://///host/directory``, and a
+            # path like ``///host/directory``. We need to special-case this
+            # because the path contains the hostname.
+            if windows_share and host is None:
+                parts = path.lstrip("\\").split("\\", 1)
+                if len(parts) == 2:
+                    host, path = parts
+                else:
+                    host = parts[0]
+                    path = ""
+        elif pathformat == "posix":
+            import posixpath
+
+            path = posixpath.normpath(path)
+        else:
+            raise TypeError("Invalid path format %s" % repr(pathformat))
+
+        if host in ("127.0.0.1", "::1", "localhost"):
+            host = None
+
+        return host, path
+
+    def _split_netloc(self):
+        if self._at in self.netloc:
+            return self.netloc.split(self._at, 1)
+        return None, self.netloc
+
+    def _split_auth(self):
+        auth = self._split_netloc()[0]
+        if not auth:
+            return None, None
+        if self._colon not in auth:
+            return auth, None
+        return auth.split(self._colon, 1)
+
+    def _split_host(self):
+        rv = self._split_netloc()[1]
+        if not rv:
+            return None, None
+
+        if not rv.startswith(self._lbracket):
+            if self._colon in rv:
+                return rv.split(self._colon, 1)
+            return rv, None
+
+        idx = rv.find(self._rbracket)
+        if idx < 0:
+            return rv, None
+
+        host = rv[1:idx]
+        rest = rv[idx + 1 :]
+        if rest.startswith(self._colon):
+            return host, rest[1:]
+        return host, None
+
+
+@implements_to_string
+class URL(BaseURL):
+    """Represents a parsed URL.  This behaves like a regular tuple but
+    also has some extra attributes that give further insight into the
+    URL.
+    """
+
+    __slots__ = ()
+    _at = "@"
+    _colon = ":"
+    _lbracket = "["
+    _rbracket = "]"
+
+    def __str__(self):
+        return self.to_url()
+
+    def encode_netloc(self):
+        """Encodes the netloc part to an ASCII safe URL as bytes."""
+        rv = self.ascii_host or ""
+        if ":" in rv:
+            rv = "[%s]" % rv
+        port = self.port
+        if port is not None:
+            rv = "%s:%d" % (rv, port)
+        auth = ":".join(
+            filter(
+                None,
+                [
+                    url_quote(self.raw_username or "", "utf-8", "strict", "/:%"),
+                    url_quote(self.raw_password or "", "utf-8", "strict", "/:%"),
+                ],
+            )
+        )
+        if auth:
+            rv = "%s@%s" % (auth, rv)
+        return to_native(rv)
+
+    def encode(self, charset="utf-8", errors="replace"):
+        """Encodes the URL to a tuple made out of bytes.  The charset is
+        only being used for the path, query and fragment.
+        """
+        return BytesURL(
+            self.scheme.encode("ascii"),
+            self.encode_netloc(),
+            self.path.encode(charset, errors),
+            self.query.encode(charset, errors),
+            self.fragment.encode(charset, errors),
+        )
+
+
+class BytesURL(BaseURL):
+    """Represents a parsed URL in bytes."""
+
+    __slots__ = ()
+    _at = b"@"
+    _colon = b":"
+    _lbracket = b"["
+    _rbracket = b"]"
+
+    def __str__(self):
+        return self.to_url().decode("utf-8", "replace")
+
+    def encode_netloc(self):
+        """Returns the netloc unchanged as bytes."""
+        return self.netloc
+
+    def decode(self, charset="utf-8", errors="replace"):
+        """Decodes the URL to a tuple made out of strings.  The charset is
+        only being used for the path, query and fragment.
+        """
+        return URL(
+            self.scheme.decode("ascii"),
+            self.decode_netloc(),
+            self.path.decode(charset, errors),
+            self.query.decode(charset, errors),
+            self.fragment.decode(charset, errors),
+        )
+
+
+_unquote_maps = {frozenset(): _hextobyte}
+
+
+def _unquote_to_bytes(string, unsafe=""):
+    if isinstance(string, text_type):
+        string = string.encode("utf-8")
+
+    if isinstance(unsafe, text_type):
+        unsafe = unsafe.encode("utf-8")
+
+    unsafe = frozenset(bytearray(unsafe))
+    groups = iter(string.split(b"%"))
+    result = bytearray(next(groups, b""))
+
+    try:
+        hex_to_byte = _unquote_maps[unsafe]
+    except KeyError:
+        hex_to_byte = _unquote_maps[unsafe] = {
+            h: b for h, b in _hextobyte.items() if b not in unsafe
+        }
+
+    for group in groups:
+        code = group[:2]
+
+        if code in hex_to_byte:
+            result.append(hex_to_byte[code])
+            result.extend(group[2:])
+        else:
+            result.append(37)  # %
+            result.extend(group)
+
+    return bytes(result)
+
+
+def _url_encode_impl(obj, charset, encode_keys, sort, key):
+    iterable = iter_multi_items(obj)
+    if sort:
+        iterable = sorted(iterable, key=key)
+    for key, value in iterable:
+        if value is None:
+            continue
+        if not isinstance(key, bytes):
+            key = text_type(key).encode(charset)
+        if not isinstance(value, bytes):
+            value = text_type(value).encode(charset)
+        yield _fast_url_quote_plus(key) + "=" + _fast_url_quote_plus(value)
+
+
+def _url_unquote_legacy(value, unsafe=""):
+    try:
+        return url_unquote(value, charset="utf-8", errors="strict", unsafe=unsafe)
+    except UnicodeError:
+        return url_unquote(value, charset="latin1", unsafe=unsafe)
+
+
+def url_parse(url, scheme=None, allow_fragments=True):
+    """Parses a URL from a string into a :class:`URL` tuple.  If the URL
+    is lacking a scheme it can be provided as second argument. Otherwise,
+    it is ignored.  Optionally fragments can be stripped from the URL
+    by setting `allow_fragments` to `False`.
+
+    The inverse of this function is :func:`url_unparse`.
+
+    :param url: the URL to parse.
+    :param scheme: the default schema to use if the URL is schemaless.
+    :param allow_fragments: if set to `False` a fragment will be removed
+                            from the URL.
+    """
+    s = make_literal_wrapper(url)
+    is_text_based = isinstance(url, text_type)
+
+    if scheme is None:
+        scheme = s("")
+    netloc = query = fragment = s("")
+    i = url.find(s(":"))
+    if i > 0 and _scheme_re.match(to_native(url[:i], errors="replace")):
+        # make sure "iri" is not actually a port number (in which case
+        # "scheme" is really part of the path)
+        rest = url[i + 1 :]
+        if not rest or any(c not in s("0123456789") for c in rest):
+            # not a port number
+            scheme, url = url[:i].lower(), rest
+
+    if url[:2] == s("//"):
+        delim = len(url)
+        for c in s("/?#"):
+            wdelim = url.find(c, 2)
+            if wdelim >= 0:
+                delim = min(delim, wdelim)
+        netloc, url = url[2:delim], url[delim:]
+        if (s("[") in netloc and s("]") not in netloc) or (
+            s("]") in netloc and s("[") not in netloc
+        ):
+            raise ValueError("Invalid IPv6 URL")
+
+    if allow_fragments and s("#") in url:
+        url, fragment = url.split(s("#"), 1)
+    if s("?") in url:
+        url, query = url.split(s("?"), 1)
+
+    result_type = URL if is_text_based else BytesURL
+    return result_type(scheme, netloc, url, query, fragment)
+
+
+def _make_fast_url_quote(charset="utf-8", errors="strict", safe="/:", unsafe=""):
+    """Precompile the translation table for a URL encoding function.
+
+    Unlike :func:`url_quote`, the generated function only takes the
+    string to quote.
+
+    :param charset: The charset to encode the result with.
+    :param errors: How to handle encoding errors.
+    :param safe: An optional sequence of safe characters to never encode.
+    :param unsafe: An optional sequence of unsafe characters to always encode.
+    """
+    if isinstance(safe, text_type):
+        safe = safe.encode(charset, errors)
+
+    if isinstance(unsafe, text_type):
+        unsafe = unsafe.encode(charset, errors)
+
+    safe = (frozenset(bytearray(safe)) | _always_safe) - frozenset(bytearray(unsafe))
+    table = [chr(c) if c in safe else "%%%02X" % c for c in range(256)]
+
+    if not PY2:
+
+        def quote(string):
+            return "".join([table[c] for c in string])
+
+    else:
+
+        def quote(string):
+            return "".join([table[c] for c in bytearray(string)])
+
+    return quote
+
+
+_fast_url_quote = _make_fast_url_quote()
+_fast_quote_plus = _make_fast_url_quote(safe=" ", unsafe="+")
+
+
+def _fast_url_quote_plus(string):
+    return _fast_quote_plus(string).replace(" ", "+")
+
+
+def url_quote(string, charset="utf-8", errors="strict", safe="/:", unsafe=""):
+    """URL encode a single string with a given encoding.
+
+    :param s: the string to quote.
+    :param charset: the charset to be used.
+    :param safe: an optional sequence of safe characters.
+    :param unsafe: an optional sequence of unsafe characters.
+
+    .. versionadded:: 0.9.2
+       The `unsafe` parameter was added.
+    """
+    if not isinstance(string, (text_type, bytes, bytearray)):
+        string = text_type(string)
+    if isinstance(string, text_type):
+        string = string.encode(charset, errors)
+    if isinstance(safe, text_type):
+        safe = safe.encode(charset, errors)
+    if isinstance(unsafe, text_type):
+        unsafe = unsafe.encode(charset, errors)
+    safe = (frozenset(bytearray(safe)) | _always_safe) - frozenset(bytearray(unsafe))
+    rv = bytearray()
+    for char in bytearray(string):
+        if char in safe:
+            rv.append(char)
+        else:
+            rv.extend(_bytetohex[char])
+    return to_native(bytes(rv))
+
+
+def url_quote_plus(string, charset="utf-8", errors="strict", safe=""):
+    """URL encode a single string with the given encoding and convert
+    whitespace to "+".
+
+    :param s: The string to quote.
+    :param charset: The charset to be used.
+    :param safe: An optional sequence of safe characters.
+    """
+    return url_quote(string, charset, errors, safe + " ", "+").replace(" ", "+")
+
+
+def url_unparse(components):
+    """The reverse operation to :meth:`url_parse`.  This accepts arbitrary
+    as well as :class:`URL` tuples and returns a URL as a string.
+
+    :param components: the parsed URL as tuple which should be converted
+                       into a URL string.
+    """
+    scheme, netloc, path, query, fragment = normalize_string_tuple(components)
+    s = make_literal_wrapper(scheme)
+    url = s("")
+
+    # We generally treat file:///x and file:/x the same which is also
+    # what browsers seem to do.  This also allows us to ignore a schema
+    # register for netloc utilization or having to differenciate between
+    # empty and missing netloc.
+    if netloc or (scheme and path.startswith(s("/"))):
+        if path and path[:1] != s("/"):
+            path = s("/") + path
+        url = s("//") + (netloc or s("")) + path
+    elif path:
+        url += path
+    if scheme:
+        url = scheme + s(":") + url
+    if query:
+        url = url + s("?") + query
+    if fragment:
+        url = url + s("#") + fragment
+    return url
+
+
+def url_unquote(string, charset="utf-8", errors="replace", unsafe=""):
+    """URL decode a single string with a given encoding.  If the charset
+    is set to `None` no unicode decoding is performed and raw bytes
+    are returned.
+
+    :param s: the string to unquote.
+    :param charset: the charset of the query string.  If set to `None`
+                    no unicode decoding will take place.
+    :param errors: the error handling for the charset decoding.
+    """
+    rv = _unquote_to_bytes(string, unsafe)
+    if charset is not None:
+        rv = rv.decode(charset, errors)
+    return rv
+
+
+def url_unquote_plus(s, charset="utf-8", errors="replace"):
+    """URL decode a single string with the given `charset` and decode "+" to
+    whitespace.
+
+    Per default encoding errors are ignored.  If you want a different behavior
+    you can set `errors` to ``'replace'`` or ``'strict'``.  In strict mode a
+    :exc:`HTTPUnicodeError` is raised.
+
+    :param s: The string to unquote.
+    :param charset: the charset of the query string.  If set to `None`
+                    no unicode decoding will take place.
+    :param errors: The error handling for the `charset` decoding.
+    """
+    if isinstance(s, text_type):
+        s = s.replace(u"+", u" ")
+    else:
+        s = s.replace(b"+", b" ")
+    return url_unquote(s, charset, errors)
+
+
+def url_fix(s, charset="utf-8"):
+    r"""Sometimes you get an URL by a user that just isn't a real URL because
+    it contains unsafe characters like ' ' and so on. This function can fix
+    some of the problems in a similar way browsers handle data entered by the
+    user:
+
+    >>> url_fix(u'http://de.wikipedia.org/wiki/Elf (Begriffskl\xe4rung)')
+    'http://de.wikipedia.org/wiki/Elf%20(Begriffskl%C3%A4rung)'
+
+    :param s: the string with the URL to fix.
+    :param charset: The target charset for the URL if the url was given as
+                    unicode string.
+    """
+    # First step is to switch to unicode processing and to convert
+    # backslashes (which are invalid in URLs anyways) to slashes.  This is
+    # consistent with what Chrome does.
+    s = to_unicode(s, charset, "replace").replace("\\", "/")
+
+    # For the specific case that we look like a malformed windows URL
+    # we want to fix this up manually:
+    if s.startswith("file://") and s[7:8].isalpha() and s[8:10] in (":/", "|/"):
+        s = "file:///" + s[7:]
+
+    url = url_parse(s)
+    path = url_quote(url.path, charset, safe="/%+$!*'(),")
+    qs = url_quote_plus(url.query, charset, safe=":&%=+$!*'(),")
+    anchor = url_quote_plus(url.fragment, charset, safe=":&%=+$!*'(),")
+    return to_native(url_unparse((url.scheme, url.encode_netloc(), path, qs, anchor)))
+
+
+# not-unreserved characters remain quoted when unquoting to IRI
+_to_iri_unsafe = "".join([chr(c) for c in range(128) if c not in _always_safe])
+
+
+def _codec_error_url_quote(e):
+    """Used in :func:`uri_to_iri` after unquoting to re-quote any
+    invalid bytes.
+    """
+    out = _fast_url_quote(e.object[e.start : e.end])
+
+    if PY2:
+        out = out.decode("utf-8")
+
+    return out, e.end
+
+
+codecs.register_error("werkzeug.url_quote", _codec_error_url_quote)
+
+
+def uri_to_iri(uri, charset="utf-8", errors="werkzeug.url_quote"):
+    """Convert a URI to an IRI. All valid UTF-8 characters are unquoted,
+    leaving all reserved and invalid characters quoted. If the URL has
+    a domain, it is decoded from Punycode.
+
+    >>> uri_to_iri("http://xn--n3h.net/p%C3%A5th?q=%C3%A8ry%DF")
+    'http://\\u2603.net/p\\xe5th?q=\\xe8ry%DF'
+
+    :param uri: The URI to convert.
+    :param charset: The encoding to encode unquoted bytes with.
+    :param errors: Error handler to use during ``bytes.encode``. By
+        default, invalid bytes are left quoted.
+
+    .. versionchanged:: 0.15
+        All reserved and invalid characters remain quoted. Previously,
+        only some reserved characters were preserved, and invalid bytes
+        were replaced instead of left quoted.
+
+    .. versionadded:: 0.6
+    """
+    if isinstance(uri, tuple):
+        uri = url_unparse(uri)
+
+    uri = url_parse(to_unicode(uri, charset))
+    path = url_unquote(uri.path, charset, errors, _to_iri_unsafe)
+    query = url_unquote(uri.query, charset, errors, _to_iri_unsafe)
+    fragment = url_unquote(uri.fragment, charset, errors, _to_iri_unsafe)
+    return url_unparse((uri.scheme, uri.decode_netloc(), path, query, fragment))
+
+
+# reserved characters remain unquoted when quoting to URI
+_to_uri_safe = ":/?#[]@!$&'()*+,;=%"
+
+
+def iri_to_uri(iri, charset="utf-8", errors="strict", safe_conversion=False):
+    """Convert an IRI to a URI. All non-ASCII and unsafe characters are
+    quoted. If the URL has a domain, it is encoded to Punycode.
+
+    >>> iri_to_uri('http://\\u2603.net/p\\xe5th?q=\\xe8ry%DF')
+    'http://xn--n3h.net/p%C3%A5th?q=%C3%A8ry%DF'
+
+    :param iri: The IRI to convert.
+    :param charset: The encoding of the IRI.
+    :param errors: Error handler to use during ``bytes.encode``.
+    :param safe_conversion: Return the URL unchanged if it only contains
+        ASCII characters and no whitespace. See the explanation below.
+
+    There is a general problem with IRI conversion with some protocols
+    that are in violation of the URI specification. Consider the
+    following two IRIs::
+
+        magnet:?xt=uri:whatever
+        itms-services://?action=download-manifest
+
+    After parsing, we don't know if the scheme requires the ``//``,
+    which is dropped if empty, but conveys different meanings in the
+    final URL if it's present or not. In this case, you can use
+    ``safe_conversion``, which will return the URL unchanged if it only
+    contains ASCII characters and no whitespace. This can result in a
+    URI with unquoted characters if it was not already quoted correctly,
+    but preserves the URL's semantics. Werkzeug uses this for the
+    ``Location`` header for redirects.
+
+    .. versionchanged:: 0.15
+        All reserved characters remain unquoted. Previously, only some
+        reserved characters were left unquoted.
+
+    .. versionchanged:: 0.9.6
+       The ``safe_conversion`` parameter was added.
+
+    .. versionadded:: 0.6
+    """
+    if isinstance(iri, tuple):
+        iri = url_unparse(iri)
+
+    if safe_conversion:
+        # If we're not sure if it's safe to convert the URL, and it only
+        # contains ASCII characters, return it unconverted.
+        try:
+            native_iri = to_native(iri)
+            ascii_iri = native_iri.encode("ascii")
+
+            # Only return if it doesn't have whitespace. (Why?)
+            if len(ascii_iri.split()) == 1:
+                return native_iri
+        except UnicodeError:
+            pass
+
+    iri = url_parse(to_unicode(iri, charset, errors))
+    path = url_quote(iri.path, charset, errors, _to_uri_safe)
+    query = url_quote(iri.query, charset, errors, _to_uri_safe)
+    fragment = url_quote(iri.fragment, charset, errors, _to_uri_safe)
+    return to_native(
+        url_unparse((iri.scheme, iri.encode_netloc(), path, query, fragment))
+    )
+
+
+def url_decode(
+    s,
+    charset="utf-8",
+    decode_keys=False,
+    include_empty=True,
+    errors="replace",
+    separator="&",
+    cls=None,
+):
+    """
+    Parse a querystring and return it as :class:`MultiDict`.  There is a
+    difference in key decoding on different Python versions.  On Python 3
+    keys will always be fully decoded whereas on Python 2, keys will
+    remain bytestrings if they fit into ASCII.  On 2.x keys can be forced
+    to be unicode by setting `decode_keys` to `True`.
+
+    If the charset is set to `None` no unicode decoding will happen and
+    raw bytes will be returned.
+
+    Per default a missing value for a key will default to an empty key.  If
+    you don't want that behavior you can set `include_empty` to `False`.
+
+    Per default encoding errors are ignored.  If you want a different behavior
+    you can set `errors` to ``'replace'`` or ``'strict'``.  In strict mode a
+    `HTTPUnicodeError` is raised.
+
+    .. versionchanged:: 0.5
+       In previous versions ";" and "&" could be used for url decoding.
+       This changed in 0.5 where only "&" is supported.  If you want to
+       use ";" instead a different `separator` can be provided.
+
+       The `cls` parameter was added.
+
+    :param s: a string with the query string to decode.
+    :param charset: the charset of the query string.  If set to `None`
+                    no unicode decoding will take place.
+    :param decode_keys: Used on Python 2.x to control whether keys should
+                        be forced to be unicode objects.  If set to `True`
+                        then keys will be unicode in all cases. Otherwise,
+                        they remain `str` if they fit into ASCII.
+    :param include_empty: Set to `False` if you don't want empty values to
+                          appear in the dict.
+    :param errors: the decoding error behavior.
+    :param separator: the pair separator to be used, defaults to ``&``
+    :param cls: an optional dict class to use.  If this is not specified
+                       or `None` the default :class:`MultiDict` is used.
+    """
+    if cls is None:
+        cls = MultiDict
+    if isinstance(s, text_type) and not isinstance(separator, text_type):
+        separator = separator.decode(charset or "ascii")
+    elif isinstance(s, bytes) and not isinstance(separator, bytes):
+        separator = separator.encode(charset or "ascii")
+    return cls(
+        _url_decode_impl(
+            s.split(separator), charset, decode_keys, include_empty, errors
+        )
+    )
+
+
+def url_decode_stream(
+    stream,
+    charset="utf-8",
+    decode_keys=False,
+    include_empty=True,
+    errors="replace",
+    separator="&",
+    cls=None,
+    limit=None,
+    return_iterator=False,
+):
+    """Works like :func:`url_decode` but decodes a stream.  The behavior
+    of stream and limit follows functions like
+    :func:`~werkzeug.wsgi.make_line_iter`.  The generator of pairs is
+    directly fed to the `cls` so you can consume the data while it's
+    parsed.
+
+    .. versionadded:: 0.8
+
+    :param stream: a stream with the encoded querystring
+    :param charset: the charset of the query string.  If set to `None`
+                    no unicode decoding will take place.
+    :param decode_keys: Used on Python 2.x to control whether keys should
+                        be forced to be unicode objects.  If set to `True`,
+                        keys will be unicode in all cases. Otherwise, they
+                        remain `str` if they fit into ASCII.
+    :param include_empty: Set to `False` if you don't want empty values to
+                          appear in the dict.
+    :param errors: the decoding error behavior.
+    :param separator: the pair separator to be used, defaults to ``&``
+    :param cls: an optional dict class to use.  If this is not specified
+                       or `None` the default :class:`MultiDict` is used.
+    :param limit: the content length of the URL data.  Not necessary if
+                  a limited stream is provided.
+    :param return_iterator: if set to `True` the `cls` argument is ignored
+                            and an iterator over all decoded pairs is
+                            returned
+    """
+    from .wsgi import make_chunk_iter
+
+    pair_iter = make_chunk_iter(stream, separator, limit)
+    decoder = _url_decode_impl(pair_iter, charset, decode_keys, include_empty, errors)
+
+    if return_iterator:
+        return decoder
+
+    if cls is None:
+        cls = MultiDict
+
+    return cls(decoder)
+
+
+def _url_decode_impl(pair_iter, charset, decode_keys, include_empty, errors):
+    for pair in pair_iter:
+        if not pair:
+            continue
+        s = make_literal_wrapper(pair)
+        equal = s("=")
+        if equal in pair:
+            key, value = pair.split(equal, 1)
+        else:
+            if not include_empty:
+                continue
+            key = pair
+            value = s("")
+        key = url_unquote_plus(key, charset, errors)
+        if charset is not None and PY2 and not decode_keys:
+            key = try_coerce_native(key)
+        yield key, url_unquote_plus(value, charset, errors)
+
+
+def url_encode(
+    obj, charset="utf-8", encode_keys=False, sort=False, key=None, separator=b"&"
+):
+    """URL encode a dict/`MultiDict`.  If a value is `None` it will not appear
+    in the result string.  Per default only values are encoded into the target
+    charset strings.  If `encode_keys` is set to ``True`` unicode keys are
+    supported too.
+
+    If `sort` is set to `True` the items are sorted by `key` or the default
+    sorting algorithm.
+
+    .. versionadded:: 0.5
+        `sort`, `key`, and `separator` were added.
+
+    :param obj: the object to encode into a query string.
+    :param charset: the charset of the query string.
+    :param encode_keys: set to `True` if you have unicode keys. (Ignored on
+                        Python 3.x)
+    :param sort: set to `True` if you want parameters to be sorted by `key`.
+    :param separator: the separator to be used for the pairs.
+    :param key: an optional function to be used for sorting.  For more details
+                check out the :func:`sorted` documentation.
+    """
+    separator = to_native(separator, "ascii")
+    return separator.join(_url_encode_impl(obj, charset, encode_keys, sort, key))
+
+
+def url_encode_stream(
+    obj,
+    stream=None,
+    charset="utf-8",
+    encode_keys=False,
+    sort=False,
+    key=None,
+    separator=b"&",
+):
+    """Like :meth:`url_encode` but writes the results to a stream
+    object.  If the stream is `None` a generator over all encoded
+    pairs is returned.
+
+    .. versionadded:: 0.8
+
+    :param obj: the object to encode into a query string.
+    :param stream: a stream to write the encoded object into or `None` if
+                   an iterator over the encoded pairs should be returned.  In
+                   that case the separator argument is ignored.
+    :param charset: the charset of the query string.
+    :param encode_keys: set to `True` if you have unicode keys. (Ignored on
+                        Python 3.x)
+    :param sort: set to `True` if you want parameters to be sorted by `key`.
+    :param separator: the separator to be used for the pairs.
+    :param key: an optional function to be used for sorting.  For more details
+                check out the :func:`sorted` documentation.
+    """
+    separator = to_native(separator, "ascii")
+    gen = _url_encode_impl(obj, charset, encode_keys, sort, key)
+    if stream is None:
+        return gen
+    for idx, chunk in enumerate(gen):
+        if idx:
+            stream.write(separator)
+        stream.write(chunk)
+
+
+def url_join(base, url, allow_fragments=True):
+    """Join a base URL and a possibly relative URL to form an absolute
+    interpretation of the latter.
+
+    :param base: the base URL for the join operation.
+    :param url: the URL to join.
+    :param allow_fragments: indicates whether fragments should be allowed.
+    """
+    if isinstance(base, tuple):
+        base = url_unparse(base)
+    if isinstance(url, tuple):
+        url = url_unparse(url)
+
+    base, url = normalize_string_tuple((base, url))
+    s = make_literal_wrapper(base)
+
+    if not base:
+        return url
+    if not url:
+        return base
+
+    bscheme, bnetloc, bpath, bquery, bfragment = url_parse(
+        base, allow_fragments=allow_fragments
+    )
+    scheme, netloc, path, query, fragment = url_parse(url, bscheme, allow_fragments)
+    if scheme != bscheme:
+        return url
+    if netloc:
+        return url_unparse((scheme, netloc, path, query, fragment))
+    netloc = bnetloc
+
+    if path[:1] == s("/"):
+        segments = path.split(s("/"))
+    elif not path:
+        segments = bpath.split(s("/"))
+        if not query:
+            query = bquery
+    else:
+        segments = bpath.split(s("/"))[:-1] + path.split(s("/"))
+
+    # If the rightmost part is "./" we want to keep the slash but
+    # remove the dot.
+    if segments[-1] == s("."):
+        segments[-1] = s("")
+
+    # Resolve ".." and "."
+    segments = [segment for segment in segments if segment != s(".")]
+    while 1:
+        i = 1
+        n = len(segments) - 1
+        while i < n:
+            if segments[i] == s("..") and segments[i - 1] not in (s(""), s("..")):
+                del segments[i - 1 : i + 1]
+                break
+            i += 1
+        else:
+            break
+
+    # Remove trailing ".." if the URL is absolute
+    unwanted_marker = [s(""), s("..")]
+    while segments[:2] == unwanted_marker:
+        del segments[1]
+
+    path = s("/").join(segments)
+    return url_unparse((scheme, netloc, path, query, fragment))
+
+
+class Href(object):
+    """Implements a callable that constructs URLs with the given base. The
+    function can be called with any number of positional and keyword
+    arguments which than are used to assemble the URL.  Works with URLs
+    and posix paths.
+
+    Positional arguments are appended as individual segments to
+    the path of the URL:
+
+    >>> href = Href('/foo')
+    >>> href('bar', 23)
+    '/foo/bar/23'
+    >>> href('foo', bar=23)
+    '/foo/foo?bar=23'
+
+    If any of the arguments (positional or keyword) evaluates to `None` it
+    will be skipped.  If no keyword arguments are given the last argument
+    can be a :class:`dict` or :class:`MultiDict` (or any other dict subclass),
+    otherwise the keyword arguments are used for the query parameters, cutting
+    off the first trailing underscore of the parameter name:
+
+    >>> href(is_=42)
+    '/foo?is=42'
+    >>> href({'foo': 'bar'})
+    '/foo?foo=bar'
+
+    Combining of both methods is not allowed:
+
+    >>> href({'foo': 'bar'}, bar=42)
+    Traceback (most recent call last):
+      ...
+    TypeError: keyword arguments and query-dicts can't be combined
+
+    Accessing attributes on the href object creates a new href object with
+    the attribute name as prefix:
+
+    >>> bar_href = href.bar
+    >>> bar_href("blub")
+    '/foo/bar/blub'
+
+    If `sort` is set to `True` the items are sorted by `key` or the default
+    sorting algorithm:
+
+    >>> href = Href("/", sort=True)
+    >>> href(a=1, b=2, c=3)
+    '/?a=1&b=2&c=3'
+
+    .. versionadded:: 0.5
+        `sort` and `key` were added.
+    """
+
+    def __init__(self, base="./", charset="utf-8", sort=False, key=None):
+        if not base:
+            base = "./"
+        self.base = base
+        self.charset = charset
+        self.sort = sort
+        self.key = key
+
+    def __getattr__(self, name):
+        if name[:2] == "__":
+            raise AttributeError(name)
+        base = self.base
+        if base[-1:] != "/":
+            base += "/"
+        return Href(url_join(base, name), self.charset, self.sort, self.key)
+
+    def __call__(self, *path, **query):
+        if path and isinstance(path[-1], dict):
+            if query:
+                raise TypeError("keyword arguments and query-dicts can't be combined")
+            query, path = path[-1], path[:-1]
+        elif query:
+            query = dict(
+                [(k.endswith("_") and k[:-1] or k, v) for k, v in query.items()]
+            )
+        path = "/".join(
+            [
+                to_unicode(url_quote(x, self.charset), "ascii")
+                for x in path
+                if x is not None
+            ]
+        ).lstrip("/")
+        rv = self.base
+        if path:
+            if not rv.endswith("/"):
+                rv += "/"
+            rv = url_join(rv, "./" + path)
+        if query:
+            rv += "?" + to_unicode(
+                url_encode(query, self.charset, sort=self.sort, key=self.key), "ascii"
+            )
+        return to_native(rv)
diff --git a/python/werkzeug/useragents.py b/python/werkzeug/useragents.py
new file mode 100644
index 0000000..e265e09
--- /dev/null
+++ b/python/werkzeug/useragents.py
@@ -0,0 +1,220 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.useragents
+    ~~~~~~~~~~~~~~~~~~~
+
+    This module provides a helper to inspect user agent strings.  This module
+    is far from complete but should work for most of the currently available
+    browsers.
+
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import re
+import warnings
+
+
+class UserAgentParser(object):
+    """A simple user agent parser.  Used by the `UserAgent`."""
+
+    platforms = (
+        ("cros", "chromeos"),
+        ("iphone|ios", "iphone"),
+        ("ipad", "ipad"),
+        (r"darwin|mac|os\s*x", "macos"),
+        ("win", "windows"),
+        (r"android", "android"),
+        ("netbsd", "netbsd"),
+        ("openbsd", "openbsd"),
+        ("freebsd", "freebsd"),
+        ("dragonfly", "dragonflybsd"),
+        ("(sun|i86)os", "solaris"),
+        (r"x11|lin(\b|ux)?", "linux"),
+        (r"nintendo\s+wii", "wii"),
+        ("irix", "irix"),
+        ("hp-?ux", "hpux"),
+        ("aix", "aix"),
+        ("sco|unix_sv", "sco"),
+        ("bsd", "bsd"),
+        ("amiga", "amiga"),
+        ("blackberry|playbook", "blackberry"),
+        ("symbian", "symbian"),
+    )
+    browsers = (
+        ("googlebot", "google"),
+        ("msnbot", "msn"),
+        ("yahoo", "yahoo"),
+        ("ask jeeves", "ask"),
+        (r"aol|america\s+online\s+browser", "aol"),
+        ("opera", "opera"),
+        ("edge", "edge"),
+        ("chrome|crios", "chrome"),
+        ("seamonkey", "seamonkey"),
+        ("firefox|firebird|phoenix|iceweasel", "firefox"),
+        ("galeon", "galeon"),
+        ("safari|version", "safari"),
+        ("webkit", "webkit"),
+        ("camino", "camino"),
+        ("konqueror", "konqueror"),
+        ("k-meleon", "kmeleon"),
+        ("netscape", "netscape"),
+        (r"msie|microsoft\s+internet\s+explorer|trident/.+? rv:", "msie"),
+        ("lynx", "lynx"),
+        ("links", "links"),
+        ("Baiduspider", "baidu"),
+        ("bingbot", "bing"),
+        ("mozilla", "mozilla"),
+    )
+
+    _browser_version_re = r"(?:%s)[/\sa-z(]*(\d+[.\da-z]+)?"
+    _language_re = re.compile(
+        r"(?:;\s*|\s+)(\b\w{2}\b(?:-\b\w{2}\b)?)\s*;|"
+        r"(?:\(|\[|;)\s*(\b\w{2}\b(?:-\b\w{2}\b)?)\s*(?:\]|\)|;)"
+    )
+
+    def __init__(self):
+        self.platforms = [(b, re.compile(a, re.I)) for a, b in self.platforms]
+        self.browsers = [
+            (b, re.compile(self._browser_version_re % a, re.I))
+            for a, b in self.browsers
+        ]
+
+    def __call__(self, user_agent):
+        for platform, regex in self.platforms:  # noqa: B007
+            match = regex.search(user_agent)
+            if match is not None:
+                break
+        else:
+            platform = None
+        for browser, regex in self.browsers:  # noqa: B007
+            match = regex.search(user_agent)
+            if match is not None:
+                version = match.group(1)
+                break
+        else:
+            browser = version = None
+        match = self._language_re.search(user_agent)
+        if match is not None:
+            language = match.group(1) or match.group(2)
+        else:
+            language = None
+        return platform, browser, version, language
+
+
+class UserAgent(object):
+    """Represents a user agent.  Pass it a WSGI environment or a user agent
+    string and you can inspect some of the details from the user agent
+    string via the attributes.  The following attributes exist:
+
+    .. attribute:: string
+
+       the raw user agent string
+
+    .. attribute:: platform
+
+       the browser platform.  The following platforms are currently
+       recognized:
+
+       -   `aix`
+       -   `amiga`
+       -   `android`
+       -   `blackberry`
+       -   `bsd`
+       -   `chromeos`
+       -   `dragonflybsd`
+       -   `freebsd`
+       -   `hpux`
+       -   `ipad`
+       -   `iphone`
+       -   `irix`
+       -   `linux`
+       -   `macos`
+       -   `netbsd`
+       -   `openbsd`
+       -   `sco`
+       -   `solaris`
+       -   `symbian`
+       -   `wii`
+       -   `windows`
+
+    .. attribute:: browser
+
+        the name of the browser.  The following browsers are currently
+        recognized:
+
+        -   `aol` *
+        -   `ask` *
+        -   `baidu` *
+        -   `bing` *
+        -   `camino`
+        -   `chrome`
+        -   `edge`
+        -   `firefox`
+        -   `galeon`
+        -   `google` *
+        -   `kmeleon`
+        -   `konqueror`
+        -   `links`
+        -   `lynx`
+        -   `mozilla`
+        -   `msie`
+        -   `msn`
+        -   `netscape`
+        -   `opera`
+        -   `safari`
+        -   `seamonkey`
+        -   `webkit`
+        -   `yahoo` *
+
+        (Browsers marked with a star (``*``) are crawlers.)
+
+    .. attribute:: version
+
+        the version of the browser
+
+    .. attribute:: language
+
+        the language of the browser
+    """
+
+    _parser = UserAgentParser()
+
+    def __init__(self, environ_or_string):
+        if isinstance(environ_or_string, dict):
+            environ_or_string = environ_or_string.get("HTTP_USER_AGENT", "")
+        self.string = environ_or_string
+        self.platform, self.browser, self.version, self.language = self._parser(
+            environ_or_string
+        )
+
+    def to_header(self):
+        return self.string
+
+    def __str__(self):
+        return self.string
+
+    def __nonzero__(self):
+        return bool(self.browser)
+
+    __bool__ = __nonzero__
+
+    def __repr__(self):
+        return "<%s %r/%s>" % (self.__class__.__name__, self.browser, self.version)
+
+
+# DEPRECATED
+from .wrappers import UserAgentMixin as _UserAgentMixin
+
+
+class UserAgentMixin(_UserAgentMixin):
+    @property
+    def user_agent(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.useragents.UserAgentMixin' should be imported"
+            " from 'werkzeug.wrappers.UserAgentMixin'. This old import"
+            " will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return super(_UserAgentMixin, self).user_agent
diff --git a/python/werkzeug/utils.py b/python/werkzeug/utils.py
new file mode 100644
index 0000000..2062057
--- /dev/null
+++ b/python/werkzeug/utils.py
@@ -0,0 +1,836 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.utils
+    ~~~~~~~~~~~~~~
+
+    This module implements various utilities for WSGI applications.  Most of
+    them are used by the request and response wrappers but especially for
+    middleware development it makes sense to use them without the wrappers.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import codecs
+import os
+import pkgutil
+import re
+import sys
+import warnings
+
+from ._compat import iteritems
+from ._compat import PY2
+from ._compat import reraise
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import unichr
+from ._internal import _DictAccessorProperty
+from ._internal import _missing
+from ._internal import _parse_signature
+
+try:
+    from html.entities import name2codepoint
+except ImportError:
+    from htmlentitydefs import name2codepoint
+
+
+_format_re = re.compile(r"\$(?:(%s)|\{(%s)\})" % (("[a-zA-Z_][a-zA-Z0-9_]*",) * 2))
+_entity_re = re.compile(r"&([^;]+);")
+_filename_ascii_strip_re = re.compile(r"[^A-Za-z0-9_.-]")
+_windows_device_files = (
+    "CON",
+    "AUX",
+    "COM1",
+    "COM2",
+    "COM3",
+    "COM4",
+    "LPT1",
+    "LPT2",
+    "LPT3",
+    "PRN",
+    "NUL",
+)
+
+
+class cached_property(property):
+    """A decorator that converts a function into a lazy property.  The
+    function wrapped is called the first time to retrieve the result
+    and then that calculated result is used the next time you access
+    the value::
+
+        class Foo(object):
+
+            @cached_property
+            def foo(self):
+                # calculate something important here
+                return 42
+
+    The class has to have a `__dict__` in order for this property to
+    work.
+    """
+
+    # implementation detail: A subclass of python's builtin property
+    # decorator, we override __get__ to check for a cached value. If one
+    # chooses to invoke __get__ by hand the property will still work as
+    # expected because the lookup logic is replicated in __get__ for
+    # manual invocation.
+
+    def __init__(self, func, name=None, doc=None):
+        self.__name__ = name or func.__name__
+        self.__module__ = func.__module__
+        self.__doc__ = doc or func.__doc__
+        self.func = func
+
+    def __set__(self, obj, value):
+        obj.__dict__[self.__name__] = value
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+        value = obj.__dict__.get(self.__name__, _missing)
+        if value is _missing:
+            value = self.func(obj)
+            obj.__dict__[self.__name__] = value
+        return value
+
+
+class environ_property(_DictAccessorProperty):
+    """Maps request attributes to environment variables. This works not only
+    for the Werzeug request object, but also any other class with an
+    environ attribute:
+
+    >>> class Test(object):
+    ...     environ = {'key': 'value'}
+    ...     test = environ_property('key')
+    >>> var = Test()
+    >>> var.test
+    'value'
+
+    If you pass it a second value it's used as default if the key does not
+    exist, the third one can be a converter that takes a value and converts
+    it.  If it raises :exc:`ValueError` or :exc:`TypeError` the default value
+    is used. If no default value is provided `None` is used.
+
+    Per default the property is read only.  You have to explicitly enable it
+    by passing ``read_only=False`` to the constructor.
+    """
+
+    read_only = True
+
+    def lookup(self, obj):
+        return obj.environ
+
+
+class header_property(_DictAccessorProperty):
+    """Like `environ_property` but for headers."""
+
+    def lookup(self, obj):
+        return obj.headers
+
+
+class HTMLBuilder(object):
+    """Helper object for HTML generation.
+
+    Per default there are two instances of that class.  The `html` one, and
+    the `xhtml` one for those two dialects.  The class uses keyword parameters
+    and positional parameters to generate small snippets of HTML.
+
+    Keyword parameters are converted to XML/SGML attributes, positional
+    arguments are used as children.  Because Python accepts positional
+    arguments before keyword arguments it's a good idea to use a list with the
+    star-syntax for some children:
+
+    >>> html.p(class_='foo', *[html.a('foo', href='foo.html'), ' ',
+    ...                        html.a('bar', href='bar.html')])
+    u'<p class="foo"><a href="foo.html">foo</a> <a href="bar.html">bar</a></p>'
+
+    This class works around some browser limitations and can not be used for
+    arbitrary SGML/XML generation.  For that purpose lxml and similar
+    libraries exist.
+
+    Calling the builder escapes the string passed:
+
+    >>> html.p(html("<foo>"))
+    u'<p>&lt;foo&gt;</p>'
+    """
+
+    _entity_re = re.compile(r"&([^;]+);")
+    _entities = name2codepoint.copy()
+    _entities["apos"] = 39
+    _empty_elements = {
+        "area",
+        "base",
+        "basefont",
+        "br",
+        "col",
+        "command",
+        "embed",
+        "frame",
+        "hr",
+        "img",
+        "input",
+        "keygen",
+        "isindex",
+        "link",
+        "meta",
+        "param",
+        "source",
+        "wbr",
+    }
+    _boolean_attributes = {
+        "selected",
+        "checked",
+        "compact",
+        "declare",
+        "defer",
+        "disabled",
+        "ismap",
+        "multiple",
+        "nohref",
+        "noresize",
+        "noshade",
+        "nowrap",
+    }
+    _plaintext_elements = {"textarea"}
+    _c_like_cdata = {"script", "style"}
+
+    def __init__(self, dialect):
+        self._dialect = dialect
+
+    def __call__(self, s):
+        return escape(s)
+
+    def __getattr__(self, tag):
+        if tag[:2] == "__":
+            raise AttributeError(tag)
+
+        def proxy(*children, **arguments):
+            buffer = "<" + tag
+            for key, value in iteritems(arguments):
+                if value is None:
+                    continue
+                if key[-1] == "_":
+                    key = key[:-1]
+                if key in self._boolean_attributes:
+                    if not value:
+                        continue
+                    if self._dialect == "xhtml":
+                        value = '="' + key + '"'
+                    else:
+                        value = ""
+                else:
+                    value = '="' + escape(value) + '"'
+                buffer += " " + key + value
+            if not children and tag in self._empty_elements:
+                if self._dialect == "xhtml":
+                    buffer += " />"
+                else:
+                    buffer += ">"
+                return buffer
+            buffer += ">"
+
+            children_as_string = "".join(
+                [text_type(x) for x in children if x is not None]
+            )
+
+            if children_as_string:
+                if tag in self._plaintext_elements:
+                    children_as_string = escape(children_as_string)
+                elif tag in self._c_like_cdata and self._dialect == "xhtml":
+                    children_as_string = (
+                        "/*<![CDATA[*/" + children_as_string + "/*]]>*/"
+                    )
+            buffer += children_as_string + "</" + tag + ">"
+            return buffer
+
+        return proxy
+
+    def __repr__(self):
+        return "<%s for %r>" % (self.__class__.__name__, self._dialect)
+
+
+html = HTMLBuilder("html")
+xhtml = HTMLBuilder("xhtml")
+
+# https://cgit.freedesktop.org/xdg/shared-mime-info/tree/freedesktop.org.xml.in
+# https://www.iana.org/assignments/media-types/media-types.xhtml
+# Types listed in the XDG mime info that have a charset in the IANA registration.
+_charset_mimetypes = {
+    "application/ecmascript",
+    "application/javascript",
+    "application/sql",
+    "application/xml",
+    "application/xml-dtd",
+    "application/xml-external-parsed-entity",
+}
+
+
+def get_content_type(mimetype, charset):
+    """Returns the full content type string with charset for a mimetype.
+
+    If the mimetype represents text, the charset parameter will be
+    appended, otherwise the mimetype is returned unchanged.
+
+    :param mimetype: The mimetype to be used as content type.
+    :param charset: The charset to be appended for text mimetypes.
+    :return: The content type.
+
+    .. verionchanged:: 0.15
+        Any type that ends with ``+xml`` gets a charset, not just those
+        that start with ``application/``. Known text types such as
+        ``application/javascript`` are also given charsets.
+    """
+    if (
+        mimetype.startswith("text/")
+        or mimetype in _charset_mimetypes
+        or mimetype.endswith("+xml")
+    ):
+        mimetype += "; charset=" + charset
+
+    return mimetype
+
+
+def detect_utf_encoding(data):
+    """Detect which UTF encoding was used to encode the given bytes.
+
+    The latest JSON standard (:rfc:`8259`) suggests that only UTF-8 is
+    accepted. Older documents allowed 8, 16, or 32. 16 and 32 can be big
+    or little endian. Some editors or libraries may prepend a BOM.
+
+    :internal:
+
+    :param data: Bytes in unknown UTF encoding.
+    :return: UTF encoding name
+
+    .. versionadded:: 0.15
+    """
+    head = data[:4]
+
+    if head[:3] == codecs.BOM_UTF8:
+        return "utf-8-sig"
+
+    if b"\x00" not in head:
+        return "utf-8"
+
+    if head in (codecs.BOM_UTF32_BE, codecs.BOM_UTF32_LE):
+        return "utf-32"
+
+    if head[:2] in (codecs.BOM_UTF16_BE, codecs.BOM_UTF16_LE):
+        return "utf-16"
+
+    if len(head) == 4:
+        if head[:3] == b"\x00\x00\x00":
+            return "utf-32-be"
+
+        if head[::2] == b"\x00\x00":
+            return "utf-16-be"
+
+        if head[1:] == b"\x00\x00\x00":
+            return "utf-32-le"
+
+        if head[1::2] == b"\x00\x00":
+            return "utf-16-le"
+
+    if len(head) == 2:
+        return "utf-16-be" if head.startswith(b"\x00") else "utf-16-le"
+
+    return "utf-8"
+
+
+def format_string(string, context):
+    """String-template format a string:
+
+    >>> format_string('$foo and ${foo}s', dict(foo=42))
+    '42 and 42s'
+
+    This does not do any attribute lookup etc.  For more advanced string
+    formattings have a look at the `werkzeug.template` module.
+
+    :param string: the format string.
+    :param context: a dict with the variables to insert.
+    """
+
+    def lookup_arg(match):
+        x = context[match.group(1) or match.group(2)]
+        if not isinstance(x, string_types):
+            x = type(string)(x)
+        return x
+
+    return _format_re.sub(lookup_arg, string)
+
+
+def secure_filename(filename):
+    r"""Pass it a filename and it will return a secure version of it.  This
+    filename can then safely be stored on a regular file system and passed
+    to :func:`os.path.join`.  The filename returned is an ASCII only string
+    for maximum portability.
+
+    On windows systems the function also makes sure that the file is not
+    named after one of the special device files.
+
+    >>> secure_filename("My cool movie.mov")
+    'My_cool_movie.mov'
+    >>> secure_filename("../../../etc/passwd")
+    'etc_passwd'
+    >>> secure_filename(u'i contain cool \xfcml\xe4uts.txt')
+    'i_contain_cool_umlauts.txt'
+
+    The function might return an empty filename.  It's your responsibility
+    to ensure that the filename is unique and that you abort or
+    generate a random filename if the function returned an empty one.
+
+    .. versionadded:: 0.5
+
+    :param filename: the filename to secure
+    """
+    if isinstance(filename, text_type):
+        from unicodedata import normalize
+
+        filename = normalize("NFKD", filename).encode("ascii", "ignore")
+        if not PY2:
+            filename = filename.decode("ascii")
+    for sep in os.path.sep, os.path.altsep:
+        if sep:
+            filename = filename.replace(sep, " ")
+    filename = str(_filename_ascii_strip_re.sub("", "_".join(filename.split()))).strip(
+        "._"
+    )
+
+    # on nt a couple of special files are present in each folder.  We
+    # have to ensure that the target file is not such a filename.  In
+    # this case we prepend an underline
+    if (
+        os.name == "nt"
+        and filename
+        and filename.split(".")[0].upper() in _windows_device_files
+    ):
+        filename = "_" + filename
+
+    return filename
+
+
+def escape(s, quote=None):
+    """Replace special characters "&", "<", ">" and (") to HTML-safe sequences.
+
+    There is a special handling for `None` which escapes to an empty string.
+
+    .. versionchanged:: 0.9
+       `quote` is now implicitly on.
+
+    :param s: the string to escape.
+    :param quote: ignored.
+    """
+    if s is None:
+        return ""
+    elif hasattr(s, "__html__"):
+        return text_type(s.__html__())
+    elif not isinstance(s, string_types):
+        s = text_type(s)
+    if quote is not None:
+        from warnings import warn
+
+        warn(
+            "The 'quote' parameter is no longer used as of version 0.9"
+            " and will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+    s = (
+        s.replace("&", "&amp;")
+        .replace("<", "&lt;")
+        .replace(">", "&gt;")
+        .replace('"', "&quot;")
+    )
+    return s
+
+
+def unescape(s):
+    """The reverse function of `escape`.  This unescapes all the HTML
+    entities, not only the XML entities inserted by `escape`.
+
+    :param s: the string to unescape.
+    """
+
+    def handle_match(m):
+        name = m.group(1)
+        if name in HTMLBuilder._entities:
+            return unichr(HTMLBuilder._entities[name])
+        try:
+            if name[:2] in ("#x", "#X"):
+                return unichr(int(name[2:], 16))
+            elif name.startswith("#"):
+                return unichr(int(name[1:]))
+        except ValueError:
+            pass
+        return u""
+
+    return _entity_re.sub(handle_match, s)
+
+
+def redirect(location, code=302, Response=None):
+    """Returns a response object (a WSGI application) that, if called,
+    redirects the client to the target location. Supported codes are
+    301, 302, 303, 305, 307, and 308. 300 is not supported because
+    it's not a real redirect and 304 because it's the answer for a
+    request with a request with defined If-Modified-Since headers.
+
+    .. versionadded:: 0.6
+       The location can now be a unicode string that is encoded using
+       the :func:`iri_to_uri` function.
+
+    .. versionadded:: 0.10
+        The class used for the Response object can now be passed in.
+
+    :param location: the location the response should redirect to.
+    :param code: the redirect status code. defaults to 302.
+    :param class Response: a Response class to use when instantiating a
+        response. The default is :class:`werkzeug.wrappers.Response` if
+        unspecified.
+    """
+    if Response is None:
+        from .wrappers import Response
+
+    display_location = escape(location)
+    if isinstance(location, text_type):
+        # Safe conversion is necessary here as we might redirect
+        # to a broken URI scheme (for instance itms-services).
+        from .urls import iri_to_uri
+
+        location = iri_to_uri(location, safe_conversion=True)
+    response = Response(
+        '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n'
+        "<title>Redirecting...</title>\n"
+        "<h1>Redirecting...</h1>\n"
+        "<p>You should be redirected automatically to target URL: "
+        '<a href="%s">%s</a>.  If not click the link.'
+        % (escape(location), display_location),
+        code,
+        mimetype="text/html",
+    )
+    response.headers["Location"] = location
+    return response
+
+
+def append_slash_redirect(environ, code=301):
+    """Redirects to the same URL but with a slash appended.  The behavior
+    of this function is undefined if the path ends with a slash already.
+
+    :param environ: the WSGI environment for the request that triggers
+                    the redirect.
+    :param code: the status code for the redirect.
+    """
+    new_path = environ["PATH_INFO"].strip("/") + "/"
+    query_string = environ.get("QUERY_STRING")
+    if query_string:
+        new_path += "?" + query_string
+    return redirect(new_path, code)
+
+
+def import_string(import_name, silent=False):
+    """Imports an object based on a string.  This is useful if you want to
+    use import paths as endpoints or something similar.  An import path can
+    be specified either in dotted notation (``xml.sax.saxutils.escape``)
+    or with a colon as object delimiter (``xml.sax.saxutils:escape``).
+
+    If `silent` is True the return value will be `None` if the import fails.
+
+    :param import_name: the dotted name for the object to import.
+    :param silent: if set to `True` import errors are ignored and
+                   `None` is returned instead.
+    :return: imported object
+    """
+    # force the import name to automatically convert to strings
+    # __import__ is not able to handle unicode strings in the fromlist
+    # if the module is a package
+    import_name = str(import_name).replace(":", ".")
+    try:
+        try:
+            __import__(import_name)
+        except ImportError:
+            if "." not in import_name:
+                raise
+        else:
+            return sys.modules[import_name]
+
+        module_name, obj_name = import_name.rsplit(".", 1)
+        module = __import__(module_name, globals(), locals(), [obj_name])
+        try:
+            return getattr(module, obj_name)
+        except AttributeError as e:
+            raise ImportError(e)
+
+    except ImportError as e:
+        if not silent:
+            reraise(
+                ImportStringError, ImportStringError(import_name, e), sys.exc_info()[2]
+            )
+
+
+def find_modules(import_path, include_packages=False, recursive=False):
+    """Finds all the modules below a package.  This can be useful to
+    automatically import all views / controllers so that their metaclasses /
+    function decorators have a chance to register themselves on the
+    application.
+
+    Packages are not returned unless `include_packages` is `True`.  This can
+    also recursively list modules but in that case it will import all the
+    packages to get the correct load path of that module.
+
+    :param import_path: the dotted name for the package to find child modules.
+    :param include_packages: set to `True` if packages should be returned, too.
+    :param recursive: set to `True` if recursion should happen.
+    :return: generator
+    """
+    module = import_string(import_path)
+    path = getattr(module, "__path__", None)
+    if path is None:
+        raise ValueError("%r is not a package" % import_path)
+    basename = module.__name__ + "."
+    for _importer, modname, ispkg in pkgutil.iter_modules(path):
+        modname = basename + modname
+        if ispkg:
+            if include_packages:
+                yield modname
+            if recursive:
+                for item in find_modules(modname, include_packages, True):
+                    yield item
+        else:
+            yield modname
+
+
+def validate_arguments(func, args, kwargs, drop_extra=True):
+    """Checks if the function accepts the arguments and keyword arguments.
+    Returns a new ``(args, kwargs)`` tuple that can safely be passed to
+    the function without causing a `TypeError` because the function signature
+    is incompatible.  If `drop_extra` is set to `True` (which is the default)
+    any extra positional or keyword arguments are dropped automatically.
+
+    The exception raised provides three attributes:
+
+    `missing`
+        A set of argument names that the function expected but where
+        missing.
+
+    `extra`
+        A dict of keyword arguments that the function can not handle but
+        where provided.
+
+    `extra_positional`
+        A list of values that where given by positional argument but the
+        function cannot accept.
+
+    This can be useful for decorators that forward user submitted data to
+    a view function::
+
+        from werkzeug.utils import ArgumentValidationError, validate_arguments
+
+        def sanitize(f):
+            def proxy(request):
+                data = request.values.to_dict()
+                try:
+                    args, kwargs = validate_arguments(f, (request,), data)
+                except ArgumentValidationError:
+                    raise BadRequest('The browser failed to transmit all '
+                                     'the data expected.')
+                return f(*args, **kwargs)
+            return proxy
+
+    :param func: the function the validation is performed against.
+    :param args: a tuple of positional arguments.
+    :param kwargs: a dict of keyword arguments.
+    :param drop_extra: set to `False` if you don't want extra arguments
+                       to be silently dropped.
+    :return: tuple in the form ``(args, kwargs)``.
+    """
+    parser = _parse_signature(func)
+    args, kwargs, missing, extra, extra_positional = parser(args, kwargs)[:5]
+    if missing:
+        raise ArgumentValidationError(tuple(missing))
+    elif (extra or extra_positional) and not drop_extra:
+        raise ArgumentValidationError(None, extra, extra_positional)
+    return tuple(args), kwargs
+
+
+def bind_arguments(func, args, kwargs):
+    """Bind the arguments provided into a dict.  When passed a function,
+    a tuple of arguments and a dict of keyword arguments `bind_arguments`
+    returns a dict of names as the function would see it.  This can be useful
+    to implement a cache decorator that uses the function arguments to build
+    the cache key based on the values of the arguments.
+
+    :param func: the function the arguments should be bound for.
+    :param args: tuple of positional arguments.
+    :param kwargs: a dict of keyword arguments.
+    :return: a :class:`dict` of bound keyword arguments.
+    """
+    (
+        args,
+        kwargs,
+        missing,
+        extra,
+        extra_positional,
+        arg_spec,
+        vararg_var,
+        kwarg_var,
+    ) = _parse_signature(func)(args, kwargs)
+    values = {}
+    for (name, _has_default, _default), value in zip(arg_spec, args):
+        values[name] = value
+    if vararg_var is not None:
+        values[vararg_var] = tuple(extra_positional)
+    elif extra_positional:
+        raise TypeError("too many positional arguments")
+    if kwarg_var is not None:
+        multikw = set(extra) & set([x[0] for x in arg_spec])
+        if multikw:
+            raise TypeError(
+                "got multiple values for keyword argument " + repr(next(iter(multikw)))
+            )
+        values[kwarg_var] = extra
+    elif extra:
+        raise TypeError("got unexpected keyword argument " + repr(next(iter(extra))))
+    return values
+
+
+class ArgumentValidationError(ValueError):
+
+    """Raised if :func:`validate_arguments` fails to validate"""
+
+    def __init__(self, missing=None, extra=None, extra_positional=None):
+        self.missing = set(missing or ())
+        self.extra = extra or {}
+        self.extra_positional = extra_positional or []
+        ValueError.__init__(
+            self,
+            "function arguments invalid. (%d missing, %d additional)"
+            % (len(self.missing), len(self.extra) + len(self.extra_positional)),
+        )
+
+
+class ImportStringError(ImportError):
+    """Provides information about a failed :func:`import_string` attempt."""
+
+    #: String in dotted notation that failed to be imported.
+    import_name = None
+    #: Wrapped exception.
+    exception = None
+
+    def __init__(self, import_name, exception):
+        self.import_name = import_name
+        self.exception = exception
+
+        msg = (
+            "import_string() failed for %r. Possible reasons are:\n\n"
+            "- missing __init__.py in a package;\n"
+            "- package or module path not included in sys.path;\n"
+            "- duplicated package or module name taking precedence in "
+            "sys.path;\n"
+            "- missing module, class, function or variable;\n\n"
+            "Debugged import:\n\n%s\n\n"
+            "Original exception:\n\n%s: %s"
+        )
+
+        name = ""
+        tracked = []
+        for part in import_name.replace(":", ".").split("."):
+            name += (name and ".") + part
+            imported = import_string(name, silent=True)
+            if imported:
+                tracked.append((name, getattr(imported, "__file__", None)))
+            else:
+                track = ["- %r found in %r." % (n, i) for n, i in tracked]
+                track.append("- %r not found." % name)
+                msg = msg % (
+                    import_name,
+                    "\n".join(track),
+                    exception.__class__.__name__,
+                    str(exception),
+                )
+                break
+
+        ImportError.__init__(self, msg)
+
+    def __repr__(self):
+        return "<%s(%r, %r)>" % (
+            self.__class__.__name__,
+            self.import_name,
+            self.exception,
+        )
+
+
+# DEPRECATED
+from .datastructures import CombinedMultiDict as _CombinedMultiDict
+from .datastructures import EnvironHeaders as _EnvironHeaders
+from .datastructures import Headers as _Headers
+from .datastructures import MultiDict as _MultiDict
+from .http import dump_cookie as _dump_cookie
+from .http import parse_cookie as _parse_cookie
+
+
+class MultiDict(_MultiDict):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.utils.MultiDict' has moved to 'werkzeug"
+            ".datastructures.MultiDict' as of version 0.5. This old"
+            " import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(MultiDict, self).__init__(*args, **kwargs)
+
+
+class CombinedMultiDict(_CombinedMultiDict):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.utils.CombinedMultiDict' has moved to 'werkzeug"
+            ".datastructures.CombinedMultiDict' as of version 0.5. This"
+            " old import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(CombinedMultiDict, self).__init__(*args, **kwargs)
+
+
+class Headers(_Headers):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.utils.Headers' has moved to 'werkzeug"
+            ".datastructures.Headers' as of version 0.5. This old"
+            " import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(Headers, self).__init__(*args, **kwargs)
+
+
+class EnvironHeaders(_EnvironHeaders):
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.utils.EnvironHeaders' has moved to 'werkzeug"
+            ".datastructures.EnvironHeaders' as of version 0.5. This"
+            " old import will be removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(EnvironHeaders, self).__init__(*args, **kwargs)
+
+
+def parse_cookie(*args, **kwargs):
+    warnings.warn(
+        "'werkzeug.utils.parse_cookie' as moved to 'werkzeug.http"
+        ".parse_cookie' as of version 0.5. This old import will be"
+        " removed in version 1.0.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return _parse_cookie(*args, **kwargs)
+
+
+def dump_cookie(*args, **kwargs):
+    warnings.warn(
+        "'werkzeug.utils.dump_cookie' as moved to 'werkzeug.http"
+        ".dump_cookie' as of version 0.5. This old import will be"
+        " removed in version 1.0.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return _dump_cookie(*args, **kwargs)
diff --git a/python/werkzeug/wrappers/__init__.py b/python/werkzeug/wrappers/__init__.py
new file mode 100644
index 0000000..56c764a
--- /dev/null
+++ b/python/werkzeug/wrappers/__init__.py
@@ -0,0 +1,36 @@
+"""
+werkzeug.wrappers
+~~~~~~~~~~~~~~~~~
+
+The wrappers are simple request and response objects which you can
+subclass to do whatever you want them to do.  The request object contains
+the information transmitted by the client (webbrowser) and the response
+object contains all the information sent back to the browser.
+
+An important detail is that the request object is created with the WSGI
+environ and will act as high-level proxy whereas the response object is an
+actual WSGI application.
+
+Like everything else in Werkzeug these objects will work correctly with
+unicode data.  Incoming form data parsed by the response object will be
+decoded into an unicode object if possible and if it makes sense.
+
+:copyright: 2007 Pallets
+:license: BSD-3-Clause
+"""
+from .accept import AcceptMixin
+from .auth import AuthorizationMixin
+from .auth import WWWAuthenticateMixin
+from .base_request import BaseRequest
+from .base_response import BaseResponse
+from .common_descriptors import CommonRequestDescriptorsMixin
+from .common_descriptors import CommonResponseDescriptorsMixin
+from .etag import ETagRequestMixin
+from .etag import ETagResponseMixin
+from .request import PlainRequest
+from .request import Request
+from .request import StreamOnlyMixin
+from .response import Response
+from .response import ResponseStream
+from .response import ResponseStreamMixin
+from .user_agent import UserAgentMixin
diff --git a/python/werkzeug/wrappers/accept.py b/python/werkzeug/wrappers/accept.py
new file mode 100644
index 0000000..d0620a0
--- /dev/null
+++ b/python/werkzeug/wrappers/accept.py
@@ -0,0 +1,50 @@
+from ..datastructures import CharsetAccept
+from ..datastructures import LanguageAccept
+from ..datastructures import MIMEAccept
+from ..http import parse_accept_header
+from ..utils import cached_property
+
+
+class AcceptMixin(object):
+    """A mixin for classes with an :attr:`~BaseResponse.environ` attribute
+    to get all the HTTP accept headers as
+    :class:`~werkzeug.datastructures.Accept` objects (or subclasses
+    thereof).
+    """
+
+    @cached_property
+    def accept_mimetypes(self):
+        """List of mimetypes this client supports as
+        :class:`~werkzeug.datastructures.MIMEAccept` object.
+        """
+        return parse_accept_header(self.environ.get("HTTP_ACCEPT"), MIMEAccept)
+
+    @cached_property
+    def accept_charsets(self):
+        """List of charsets this client supports as
+        :class:`~werkzeug.datastructures.CharsetAccept` object.
+        """
+        return parse_accept_header(
+            self.environ.get("HTTP_ACCEPT_CHARSET"), CharsetAccept
+        )
+
+    @cached_property
+    def accept_encodings(self):
+        """List of encodings this client accepts.  Encodings in a HTTP term
+        are compression encodings such as gzip.  For charsets have a look at
+        :attr:`accept_charset`.
+        """
+        return parse_accept_header(self.environ.get("HTTP_ACCEPT_ENCODING"))
+
+    @cached_property
+    def accept_languages(self):
+        """List of languages this client accepts as
+        :class:`~werkzeug.datastructures.LanguageAccept` object.
+
+        .. versionchanged 0.5
+           In previous versions this was a regular
+           :class:`~werkzeug.datastructures.Accept` object.
+        """
+        return parse_accept_header(
+            self.environ.get("HTTP_ACCEPT_LANGUAGE"), LanguageAccept
+        )
diff --git a/python/werkzeug/wrappers/auth.py b/python/werkzeug/wrappers/auth.py
new file mode 100644
index 0000000..714f755
--- /dev/null
+++ b/python/werkzeug/wrappers/auth.py
@@ -0,0 +1,33 @@
+from ..http import parse_authorization_header
+from ..http import parse_www_authenticate_header
+from ..utils import cached_property
+
+
+class AuthorizationMixin(object):
+    """Adds an :attr:`authorization` property that represents the parsed
+    value of the `Authorization` header as
+    :class:`~werkzeug.datastructures.Authorization` object.
+    """
+
+    @cached_property
+    def authorization(self):
+        """The `Authorization` object in parsed form."""
+        header = self.environ.get("HTTP_AUTHORIZATION")
+        return parse_authorization_header(header)
+
+
+class WWWAuthenticateMixin(object):
+    """Adds a :attr:`www_authenticate` property to a response object."""
+
+    @property
+    def www_authenticate(self):
+        """The `WWW-Authenticate` header in a parsed form."""
+
+        def on_update(www_auth):
+            if not www_auth and "www-authenticate" in self.headers:
+                del self.headers["www-authenticate"]
+            elif www_auth:
+                self.headers["WWW-Authenticate"] = www_auth.to_header()
+
+        header = self.headers.get("www-authenticate")
+        return parse_www_authenticate_header(header, on_update)
diff --git a/python/werkzeug/wrappers/base_request.py b/python/werkzeug/wrappers/base_request.py
new file mode 100644
index 0000000..41e8aad
--- /dev/null
+++ b/python/werkzeug/wrappers/base_request.py
@@ -0,0 +1,693 @@
+import warnings
+from functools import update_wrapper
+from io import BytesIO
+
+from .._compat import to_native
+from .._compat import to_unicode
+from .._compat import wsgi_decoding_dance
+from .._compat import wsgi_get_bytes
+from ..datastructures import CombinedMultiDict
+from ..datastructures import EnvironHeaders
+from ..datastructures import ImmutableList
+from ..datastructures import ImmutableMultiDict
+from ..datastructures import ImmutableTypeConversionDict
+from ..datastructures import iter_multi_items
+from ..datastructures import MultiDict
+from ..formparser import default_stream_factory
+from ..formparser import FormDataParser
+from ..http import parse_cookie
+from ..http import parse_options_header
+from ..urls import url_decode
+from ..utils import cached_property
+from ..utils import environ_property
+from ..wsgi import get_content_length
+from ..wsgi import get_current_url
+from ..wsgi import get_host
+from ..wsgi import get_input_stream
+
+
+class BaseRequest(object):
+    """Very basic request object.  This does not implement advanced stuff like
+    entity tag parsing or cache controls.  The request object is created with
+    the WSGI environment as first argument and will add itself to the WSGI
+    environment as ``'werkzeug.request'`` unless it's created with
+    `populate_request` set to False.
+
+    There are a couple of mixins available that add additional functionality
+    to the request object, there is also a class called `Request` which
+    subclasses `BaseRequest` and all the important mixins.
+
+    It's a good idea to create a custom subclass of the :class:`BaseRequest`
+    and add missing functionality either via mixins or direct implementation.
+    Here an example for such subclasses::
+
+        from werkzeug.wrappers import BaseRequest, ETagRequestMixin
+
+        class Request(BaseRequest, ETagRequestMixin):
+            pass
+
+    Request objects are **read only**.  As of 0.5 modifications are not
+    allowed in any place.  Unlike the lower level parsing functions the
+    request object will use immutable objects everywhere possible.
+
+    Per default the request object will assume all the text data is `utf-8`
+    encoded.  Please refer to :doc:`the unicode chapter </unicode>` for more
+    details about customizing the behavior.
+
+    Per default the request object will be added to the WSGI
+    environment as `werkzeug.request` to support the debugging system.
+    If you don't want that, set `populate_request` to `False`.
+
+    If `shallow` is `True` the environment is initialized as shallow
+    object around the environ.  Every operation that would modify the
+    environ in any way (such as consuming form data) raises an exception
+    unless the `shallow` attribute is explicitly set to `False`.  This
+    is useful for middlewares where you don't want to consume the form
+    data by accident.  A shallow request is not populated to the WSGI
+    environment.
+
+    .. versionchanged:: 0.5
+       read-only mode was enforced by using immutables classes for all
+       data.
+    """
+
+    #: the charset for the request, defaults to utf-8
+    charset = "utf-8"
+
+    #: the error handling procedure for errors, defaults to 'replace'
+    encoding_errors = "replace"
+
+    #: the maximum content length.  This is forwarded to the form data
+    #: parsing function (:func:`parse_form_data`).  When set and the
+    #: :attr:`form` or :attr:`files` attribute is accessed and the
+    #: parsing fails because more than the specified value is transmitted
+    #: a :exc:`~werkzeug.exceptions.RequestEntityTooLarge` exception is raised.
+    #:
+    #: Have a look at :ref:`dealing-with-request-data` for more details.
+    #:
+    #: .. versionadded:: 0.5
+    max_content_length = None
+
+    #: the maximum form field size.  This is forwarded to the form data
+    #: parsing function (:func:`parse_form_data`).  When set and the
+    #: :attr:`form` or :attr:`files` attribute is accessed and the
+    #: data in memory for post data is longer than the specified value a
+    #: :exc:`~werkzeug.exceptions.RequestEntityTooLarge` exception is raised.
+    #:
+    #: Have a look at :ref:`dealing-with-request-data` for more details.
+    #:
+    #: .. versionadded:: 0.5
+    max_form_memory_size = None
+
+    #: the class to use for `args` and `form`.  The default is an
+    #: :class:`~werkzeug.datastructures.ImmutableMultiDict` which supports
+    #: multiple values per key.  alternatively it makes sense to use an
+    #: :class:`~werkzeug.datastructures.ImmutableOrderedMultiDict` which
+    #: preserves order or a :class:`~werkzeug.datastructures.ImmutableDict`
+    #: which is the fastest but only remembers the last key.  It is also
+    #: possible to use mutable structures, but this is not recommended.
+    #:
+    #: .. versionadded:: 0.6
+    parameter_storage_class = ImmutableMultiDict
+
+    #: the type to be used for list values from the incoming WSGI environment.
+    #: By default an :class:`~werkzeug.datastructures.ImmutableList` is used
+    #: (for example for :attr:`access_list`).
+    #:
+    #: .. versionadded:: 0.6
+    list_storage_class = ImmutableList
+
+    #: the type to be used for dict values from the incoming WSGI environment.
+    #: By default an
+    #: :class:`~werkzeug.datastructures.ImmutableTypeConversionDict` is used
+    #: (for example for :attr:`cookies`).
+    #:
+    #: .. versionadded:: 0.6
+    dict_storage_class = ImmutableTypeConversionDict
+
+    #: The form data parser that shoud be used.  Can be replaced to customize
+    #: the form date parsing.
+    form_data_parser_class = FormDataParser
+
+    #: Optionally a list of hosts that is trusted by this request.  By default
+    #: all hosts are trusted which means that whatever the client sends the
+    #: host is will be accepted.
+    #:
+    #: Because `Host` and `X-Forwarded-Host` headers can be set to any value by
+    #: a malicious client, it is recommended to either set this property or
+    #: implement similar validation in the proxy (if application is being run
+    #: behind one).
+    #:
+    #: .. versionadded:: 0.9
+    trusted_hosts = None
+
+    #: Indicates whether the data descriptor should be allowed to read and
+    #: buffer up the input stream.  By default it's enabled.
+    #:
+    #: .. versionadded:: 0.9
+    disable_data_descriptor = False
+
+    def __init__(self, environ, populate_request=True, shallow=False):
+        self.environ = environ
+        if populate_request and not shallow:
+            self.environ["werkzeug.request"] = self
+        self.shallow = shallow
+
+    def __repr__(self):
+        # make sure the __repr__ even works if the request was created
+        # from an invalid WSGI environment.  If we display the request
+        # in a debug session we don't want the repr to blow up.
+        args = []
+        try:
+            args.append("'%s'" % to_native(self.url, self.url_charset))
+            args.append("[%s]" % self.method)
+        except Exception:
+            args.append("(invalid WSGI environ)")
+
+        return "<%s %s>" % (self.__class__.__name__, " ".join(args))
+
+    @property
+    def url_charset(self):
+        """The charset that is assumed for URLs.  Defaults to the value
+        of :attr:`charset`.
+
+        .. versionadded:: 0.6
+        """
+        return self.charset
+
+    @classmethod
+    def from_values(cls, *args, **kwargs):
+        """Create a new request object based on the values provided.  If
+        environ is given missing values are filled from there.  This method is
+        useful for small scripts when you need to simulate a request from an URL.
+        Do not use this method for unittesting, there is a full featured client
+        object (:class:`Client`) that allows to create multipart requests,
+        support for cookies etc.
+
+        This accepts the same options as the
+        :class:`~werkzeug.test.EnvironBuilder`.
+
+        .. versionchanged:: 0.5
+           This method now accepts the same arguments as
+           :class:`~werkzeug.test.EnvironBuilder`.  Because of this the
+           `environ` parameter is now called `environ_overrides`.
+
+        :return: request object
+        """
+        from ..test import EnvironBuilder
+
+        charset = kwargs.pop("charset", cls.charset)
+        kwargs["charset"] = charset
+        builder = EnvironBuilder(*args, **kwargs)
+        try:
+            return builder.get_request(cls)
+        finally:
+            builder.close()
+
+    @classmethod
+    def application(cls, f):
+        """Decorate a function as responder that accepts the request as first
+        argument.  This works like the :func:`responder` decorator but the
+        function is passed the request object as first argument and the
+        request object will be closed automatically::
+
+            @Request.application
+            def my_wsgi_app(request):
+                return Response('Hello World!')
+
+        As of Werkzeug 0.14 HTTP exceptions are automatically caught and
+        converted to responses instead of failing.
+
+        :param f: the WSGI callable to decorate
+        :return: a new WSGI callable
+        """
+        #: return a callable that wraps the -2nd argument with the request
+        #: and calls the function with all the arguments up to that one and
+        #: the request.  The return value is then called with the latest
+        #: two arguments.  This makes it possible to use this decorator for
+        #: both methods and standalone WSGI functions.
+        from ..exceptions import HTTPException
+
+        def application(*args):
+            request = cls(args[-2])
+            with request:
+                try:
+                    resp = f(*args[:-2] + (request,))
+                except HTTPException as e:
+                    resp = e.get_response(args[-2])
+                return resp(*args[-2:])
+
+        return update_wrapper(application, f)
+
+    def _get_file_stream(
+        self, total_content_length, content_type, filename=None, content_length=None
+    ):
+        """Called to get a stream for the file upload.
+
+        This must provide a file-like class with `read()`, `readline()`
+        and `seek()` methods that is both writeable and readable.
+
+        The default implementation returns a temporary file if the total
+        content length is higher than 500KB.  Because many browsers do not
+        provide a content length for the files only the total content
+        length matters.
+
+        :param total_content_length: the total content length of all the
+                                     data in the request combined.  This value
+                                     is guaranteed to be there.
+        :param content_type: the mimetype of the uploaded file.
+        :param filename: the filename of the uploaded file.  May be `None`.
+        :param content_length: the length of this file.  This value is usually
+                               not provided because webbrowsers do not provide
+                               this value.
+        """
+        return default_stream_factory(
+            total_content_length=total_content_length,
+            filename=filename,
+            content_type=content_type,
+            content_length=content_length,
+        )
+
+    @property
+    def want_form_data_parsed(self):
+        """Returns True if the request method carries content.  As of
+        Werkzeug 0.9 this will be the case if a content type is transmitted.
+
+        .. versionadded:: 0.8
+        """
+        return bool(self.environ.get("CONTENT_TYPE"))
+
+    def make_form_data_parser(self):
+        """Creates the form data parser. Instantiates the
+        :attr:`form_data_parser_class` with some parameters.
+
+        .. versionadded:: 0.8
+        """
+        return self.form_data_parser_class(
+            self._get_file_stream,
+            self.charset,
+            self.encoding_errors,
+            self.max_form_memory_size,
+            self.max_content_length,
+            self.parameter_storage_class,
+        )
+
+    def _load_form_data(self):
+        """Method used internally to retrieve submitted data.  After calling
+        this sets `form` and `files` on the request object to multi dicts
+        filled with the incoming form data.  As a matter of fact the input
+        stream will be empty afterwards.  You can also call this method to
+        force the parsing of the form data.
+
+        .. versionadded:: 0.8
+        """
+        # abort early if we have already consumed the stream
+        if "form" in self.__dict__:
+            return
+
+        _assert_not_shallow(self)
+
+        if self.want_form_data_parsed:
+            content_type = self.environ.get("CONTENT_TYPE", "")
+            content_length = get_content_length(self.environ)
+            mimetype, options = parse_options_header(content_type)
+            parser = self.make_form_data_parser()
+            data = parser.parse(
+                self._get_stream_for_parsing(), mimetype, content_length, options
+            )
+        else:
+            data = (
+                self.stream,
+                self.parameter_storage_class(),
+                self.parameter_storage_class(),
+            )
+
+        # inject the values into the instance dict so that we bypass
+        # our cached_property non-data descriptor.
+        d = self.__dict__
+        d["stream"], d["form"], d["files"] = data
+
+    def _get_stream_for_parsing(self):
+        """This is the same as accessing :attr:`stream` with the difference
+        that if it finds cached data from calling :meth:`get_data` first it
+        will create a new stream out of the cached data.
+
+        .. versionadded:: 0.9.3
+        """
+        cached_data = getattr(self, "_cached_data", None)
+        if cached_data is not None:
+            return BytesIO(cached_data)
+        return self.stream
+
+    def close(self):
+        """Closes associated resources of this request object.  This
+        closes all file handles explicitly.  You can also use the request
+        object in a with statement which will automatically close it.
+
+        .. versionadded:: 0.9
+        """
+        files = self.__dict__.get("files")
+        for _key, value in iter_multi_items(files or ()):
+            value.close()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.close()
+
+    @cached_property
+    def stream(self):
+        """
+        If the incoming form data was not encoded with a known mimetype
+        the data is stored unmodified in this stream for consumption.  Most
+        of the time it is a better idea to use :attr:`data` which will give
+        you that data as a string.  The stream only returns the data once.
+
+        Unlike :attr:`input_stream` this stream is properly guarded that you
+        can't accidentally read past the length of the input.  Werkzeug will
+        internally always refer to this stream to read data which makes it
+        possible to wrap this object with a stream that does filtering.
+
+        .. versionchanged:: 0.9
+           This stream is now always available but might be consumed by the
+           form parser later on.  Previously the stream was only set if no
+           parsing happened.
+        """
+        _assert_not_shallow(self)
+        return get_input_stream(self.environ)
+
+    input_stream = environ_property(
+        "wsgi.input",
+        """The WSGI input stream.
+
+        In general it's a bad idea to use this one because you can
+        easily read past the boundary.  Use the :attr:`stream`
+        instead.""",
+    )
+
+    @cached_property
+    def args(self):
+        """The parsed URL parameters (the part in the URL after the question
+        mark).
+
+        By default an
+        :class:`~werkzeug.datastructures.ImmutableMultiDict`
+        is returned from this function.  This can be changed by setting
+        :attr:`parameter_storage_class` to a different type.  This might
+        be necessary if the order of the form data is important.
+        """
+        return url_decode(
+            wsgi_get_bytes(self.environ.get("QUERY_STRING", "")),
+            self.url_charset,
+            errors=self.encoding_errors,
+            cls=self.parameter_storage_class,
+        )
+
+    @cached_property
+    def data(self):
+        """
+        Contains the incoming request data as string in case it came with
+        a mimetype Werkzeug does not handle.
+        """
+
+        if self.disable_data_descriptor:
+            raise AttributeError("data descriptor is disabled")
+        # XXX: this should eventually be deprecated.
+
+        # We trigger form data parsing first which means that the descriptor
+        # will not cache the data that would otherwise be .form or .files
+        # data.  This restores the behavior that was there in Werkzeug
+        # before 0.9.  New code should use :meth:`get_data` explicitly as
+        # this will make behavior explicit.
+        return self.get_data(parse_form_data=True)
+
+    def get_data(self, cache=True, as_text=False, parse_form_data=False):
+        """This reads the buffered incoming data from the client into one
+        bytestring.  By default this is cached but that behavior can be
+        changed by setting `cache` to `False`.
+
+        Usually it's a bad idea to call this method without checking the
+        content length first as a client could send dozens of megabytes or more
+        to cause memory problems on the server.
+
+        Note that if the form data was already parsed this method will not
+        return anything as form data parsing does not cache the data like
+        this method does.  To implicitly invoke form data parsing function
+        set `parse_form_data` to `True`.  When this is done the return value
+        of this method will be an empty string if the form parser handles
+        the data.  This generally is not necessary as if the whole data is
+        cached (which is the default) the form parser will used the cached
+        data to parse the form data.  Please be generally aware of checking
+        the content length first in any case before calling this method
+        to avoid exhausting server memory.
+
+        If `as_text` is set to `True` the return value will be a decoded
+        unicode string.
+
+        .. versionadded:: 0.9
+        """
+        rv = getattr(self, "_cached_data", None)
+        if rv is None:
+            if parse_form_data:
+                self._load_form_data()
+            rv = self.stream.read()
+            if cache:
+                self._cached_data = rv
+        if as_text:
+            rv = rv.decode(self.charset, self.encoding_errors)
+        return rv
+
+    @cached_property
+    def form(self):
+        """The form parameters.  By default an
+        :class:`~werkzeug.datastructures.ImmutableMultiDict`
+        is returned from this function.  This can be changed by setting
+        :attr:`parameter_storage_class` to a different type.  This might
+        be necessary if the order of the form data is important.
+
+        Please keep in mind that file uploads will not end up here, but instead
+        in the :attr:`files` attribute.
+
+        .. versionchanged:: 0.9
+
+            Previous to Werkzeug 0.9 this would only contain form data for POST
+            and PUT requests.
+        """
+        self._load_form_data()
+        return self.form
+
+    @cached_property
+    def values(self):
+        """A :class:`werkzeug.datastructures.CombinedMultiDict` that combines
+        :attr:`args` and :attr:`form`."""
+        args = []
+        for d in self.args, self.form:
+            if not isinstance(d, MultiDict):
+                d = MultiDict(d)
+            args.append(d)
+        return CombinedMultiDict(args)
+
+    @cached_property
+    def files(self):
+        """:class:`~werkzeug.datastructures.MultiDict` object containing
+        all uploaded files.  Each key in :attr:`files` is the name from the
+        ``<input type="file" name="">``.  Each value in :attr:`files` is a
+        Werkzeug :class:`~werkzeug.datastructures.FileStorage` object.
+
+        It basically behaves like a standard file object you know from Python,
+        with the difference that it also has a
+        :meth:`~werkzeug.datastructures.FileStorage.save` function that can
+        store the file on the filesystem.
+
+        Note that :attr:`files` will only contain data if the request method was
+        POST, PUT or PATCH and the ``<form>`` that posted to the request had
+        ``enctype="multipart/form-data"``.  It will be empty otherwise.
+
+        See the :class:`~werkzeug.datastructures.MultiDict` /
+        :class:`~werkzeug.datastructures.FileStorage` documentation for
+        more details about the used data structure.
+        """
+        self._load_form_data()
+        return self.files
+
+    @cached_property
+    def cookies(self):
+        """A :class:`dict` with the contents of all cookies transmitted with
+        the request."""
+        return parse_cookie(
+            self.environ,
+            self.charset,
+            self.encoding_errors,
+            cls=self.dict_storage_class,
+        )
+
+    @cached_property
+    def headers(self):
+        """The headers from the WSGI environ as immutable
+        :class:`~werkzeug.datastructures.EnvironHeaders`.
+        """
+        return EnvironHeaders(self.environ)
+
+    @cached_property
+    def path(self):
+        """Requested path as unicode.  This works a bit like the regular path
+        info in the WSGI environment but will always include a leading slash,
+        even if the URL root is accessed.
+        """
+        raw_path = wsgi_decoding_dance(
+            self.environ.get("PATH_INFO") or "", self.charset, self.encoding_errors
+        )
+        return "/" + raw_path.lstrip("/")
+
+    @cached_property
+    def full_path(self):
+        """Requested path as unicode, including the query string."""
+        return self.path + u"?" + to_unicode(self.query_string, self.url_charset)
+
+    @cached_property
+    def script_root(self):
+        """The root path of the script without the trailing slash."""
+        raw_path = wsgi_decoding_dance(
+            self.environ.get("SCRIPT_NAME") or "", self.charset, self.encoding_errors
+        )
+        return raw_path.rstrip("/")
+
+    @cached_property
+    def url(self):
+        """The reconstructed current URL as IRI.
+        See also: :attr:`trusted_hosts`.
+        """
+        return get_current_url(self.environ, trusted_hosts=self.trusted_hosts)
+
+    @cached_property
+    def base_url(self):
+        """Like :attr:`url` but without the querystring
+        See also: :attr:`trusted_hosts`.
+        """
+        return get_current_url(
+            self.environ, strip_querystring=True, trusted_hosts=self.trusted_hosts
+        )
+
+    @cached_property
+    def url_root(self):
+        """The full URL root (with hostname), this is the application
+        root as IRI.
+        See also: :attr:`trusted_hosts`.
+        """
+        return get_current_url(self.environ, True, trusted_hosts=self.trusted_hosts)
+
+    @cached_property
+    def host_url(self):
+        """Just the host with scheme as IRI.
+        See also: :attr:`trusted_hosts`.
+        """
+        return get_current_url(
+            self.environ, host_only=True, trusted_hosts=self.trusted_hosts
+        )
+
+    @cached_property
+    def host(self):
+        """Just the host including the port if available.
+        See also: :attr:`trusted_hosts`.
+        """
+        return get_host(self.environ, trusted_hosts=self.trusted_hosts)
+
+    query_string = environ_property(
+        "QUERY_STRING",
+        "",
+        read_only=True,
+        load_func=wsgi_get_bytes,
+        doc="The URL parameters as raw bytestring.",
+    )
+    method = environ_property(
+        "REQUEST_METHOD",
+        "GET",
+        read_only=True,
+        load_func=lambda x: x.upper(),
+        doc="The request method. (For example ``'GET'`` or ``'POST'``).",
+    )
+
+    @cached_property
+    def access_route(self):
+        """If a forwarded header exists this is a list of all ip addresses
+        from the client ip to the last proxy server.
+        """
+        if "HTTP_X_FORWARDED_FOR" in self.environ:
+            addr = self.environ["HTTP_X_FORWARDED_FOR"].split(",")
+            return self.list_storage_class([x.strip() for x in addr])
+        elif "REMOTE_ADDR" in self.environ:
+            return self.list_storage_class([self.environ["REMOTE_ADDR"]])
+        return self.list_storage_class()
+
+    @property
+    def remote_addr(self):
+        """The remote address of the client."""
+        return self.environ.get("REMOTE_ADDR")
+
+    remote_user = environ_property(
+        "REMOTE_USER",
+        doc="""If the server supports user authentication, and the
+        script is protected, this attribute contains the username the
+        user has authenticated as.""",
+    )
+
+    scheme = environ_property(
+        "wsgi.url_scheme",
+        doc="""
+        URL scheme (http or https).
+
+        .. versionadded:: 0.7""",
+    )
+
+    @property
+    def is_xhr(self):
+        """True if the request was triggered via a JavaScript XMLHttpRequest.
+        This only works with libraries that support the ``X-Requested-With``
+        header and set it to "XMLHttpRequest".  Libraries that do that are
+        prototype, jQuery and Mochikit and probably some more.
+
+        .. deprecated:: 0.13
+            ``X-Requested-With`` is not standard and is unreliable. You
+            may be able to use :attr:`AcceptMixin.accept_mimetypes`
+            instead.
+        """
+        warnings.warn(
+            "'Request.is_xhr' is deprecated as of version 0.13 and will"
+            " be removed in version 1.0. The 'X-Requested-With' header"
+            " is not standard and is unreliable. You may be able to use"
+            " 'accept_mimetypes' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.environ.get("HTTP_X_REQUESTED_WITH", "").lower() == "xmlhttprequest"
+
+    is_secure = property(
+        lambda self: self.environ["wsgi.url_scheme"] == "https",
+        doc="`True` if the request is secure.",
+    )
+    is_multithread = environ_property(
+        "wsgi.multithread",
+        doc="""boolean that is `True` if the application is served by a
+        multithreaded WSGI server.""",
+    )
+    is_multiprocess = environ_property(
+        "wsgi.multiprocess",
+        doc="""boolean that is `True` if the application is served by a
+        WSGI server that spawns multiple processes.""",
+    )
+    is_run_once = environ_property(
+        "wsgi.run_once",
+        doc="""boolean that is `True` if the application will be
+        executed only once in a process lifetime.  This is the case for
+        CGI for example, but it's not guaranteed that the execution only
+        happens one time.""",
+    )
+
+
+def _assert_not_shallow(request):
+    if request.shallow:
+        raise RuntimeError(
+            "A shallow request tried to consume form data. If you really"
+            " want to do that, set `shallow` to False."
+        )
diff --git a/python/werkzeug/wrappers/base_response.py b/python/werkzeug/wrappers/base_response.py
new file mode 100644
index 0000000..d944a7d
--- /dev/null
+++ b/python/werkzeug/wrappers/base_response.py
@@ -0,0 +1,702 @@
+import warnings
+
+from .._compat import integer_types
+from .._compat import string_types
+from .._compat import text_type
+from .._compat import to_bytes
+from .._compat import to_native
+from ..datastructures import Headers
+from ..http import dump_cookie
+from ..http import HTTP_STATUS_CODES
+from ..http import remove_entity_headers
+from ..urls import iri_to_uri
+from ..urls import url_join
+from ..utils import get_content_type
+from ..wsgi import ClosingIterator
+from ..wsgi import get_current_url
+
+
+def _run_wsgi_app(*args):
+    """This function replaces itself to ensure that the test module is not
+    imported unless required.  DO NOT USE!
+    """
+    global _run_wsgi_app
+    from ..test import run_wsgi_app as _run_wsgi_app
+
+    return _run_wsgi_app(*args)
+
+
+def _warn_if_string(iterable):
+    """Helper for the response objects to check if the iterable returned
+    to the WSGI server is not a string.
+    """
+    if isinstance(iterable, string_types):
+        warnings.warn(
+            "Response iterable was set to a string. This will appear to"
+            " work but means that the server will send the data to the"
+            " client one character at a time. This is almost never"
+            " intended behavior, use 'response.data' to assign strings"
+            " to the response object.",
+            stacklevel=2,
+        )
+
+
+def _iter_encoded(iterable, charset):
+    for item in iterable:
+        if isinstance(item, text_type):
+            yield item.encode(charset)
+        else:
+            yield item
+
+
+def _clean_accept_ranges(accept_ranges):
+    if accept_ranges is True:
+        return "bytes"
+    elif accept_ranges is False:
+        return "none"
+    elif isinstance(accept_ranges, text_type):
+        return to_native(accept_ranges)
+    raise ValueError("Invalid accept_ranges value")
+
+
+class BaseResponse(object):
+    """Base response class.  The most important fact about a response object
+    is that it's a regular WSGI application.  It's initialized with a couple
+    of response parameters (headers, body, status code etc.) and will start a
+    valid WSGI response when called with the environ and start response
+    callable.
+
+    Because it's a WSGI application itself processing usually ends before the
+    actual response is sent to the server.  This helps debugging systems
+    because they can catch all the exceptions before responses are started.
+
+    Here a small example WSGI application that takes advantage of the
+    response objects::
+
+        from werkzeug.wrappers import BaseResponse as Response
+
+        def index():
+            return Response('Index page')
+
+        def application(environ, start_response):
+            path = environ.get('PATH_INFO') or '/'
+            if path == '/':
+                response = index()
+            else:
+                response = Response('Not Found', status=404)
+            return response(environ, start_response)
+
+    Like :class:`BaseRequest` which object is lacking a lot of functionality
+    implemented in mixins.  This gives you a better control about the actual
+    API of your response objects, so you can create subclasses and add custom
+    functionality.  A full featured response object is available as
+    :class:`Response` which implements a couple of useful mixins.
+
+    To enforce a new type of already existing responses you can use the
+    :meth:`force_type` method.  This is useful if you're working with different
+    subclasses of response objects and you want to post process them with a
+    known interface.
+
+    Per default the response object will assume all the text data is `utf-8`
+    encoded.  Please refer to :doc:`the unicode chapter </unicode>` for more
+    details about customizing the behavior.
+
+    Response can be any kind of iterable or string.  If it's a string it's
+    considered being an iterable with one item which is the string passed.
+    Headers can be a list of tuples or a
+    :class:`~werkzeug.datastructures.Headers` object.
+
+    Special note for `mimetype` and `content_type`:  For most mime types
+    `mimetype` and `content_type` work the same, the difference affects
+    only 'text' mimetypes.  If the mimetype passed with `mimetype` is a
+    mimetype starting with `text/`, the charset parameter of the response
+    object is appended to it.  In contrast the `content_type` parameter is
+    always added as header unmodified.
+
+    .. versionchanged:: 0.5
+       the `direct_passthrough` parameter was added.
+
+    :param response: a string or response iterable.
+    :param status: a string with a status or an integer with the status code.
+    :param headers: a list of headers or a
+                    :class:`~werkzeug.datastructures.Headers` object.
+    :param mimetype: the mimetype for the response.  See notice above.
+    :param content_type: the content type for the response.  See notice above.
+    :param direct_passthrough: if set to `True` :meth:`iter_encoded` is not
+                               called before iteration which makes it
+                               possible to pass special iterators through
+                               unchanged (see :func:`wrap_file` for more
+                               details.)
+    """
+
+    #: the charset of the response.
+    charset = "utf-8"
+
+    #: the default status if none is provided.
+    default_status = 200
+
+    #: the default mimetype if none is provided.
+    default_mimetype = "text/plain"
+
+    #: if set to `False` accessing properties on the response object will
+    #: not try to consume the response iterator and convert it into a list.
+    #:
+    #: .. versionadded:: 0.6.2
+    #:
+    #:    That attribute was previously called `implicit_seqence_conversion`.
+    #:    (Notice the typo).  If you did use this feature, you have to adapt
+    #:    your code to the name change.
+    implicit_sequence_conversion = True
+
+    #: Should this response object correct the location header to be RFC
+    #: conformant?  This is true by default.
+    #:
+    #: .. versionadded:: 0.8
+    autocorrect_location_header = True
+
+    #: Should this response object automatically set the content-length
+    #: header if possible?  This is true by default.
+    #:
+    #: .. versionadded:: 0.8
+    automatically_set_content_length = True
+
+    #: Warn if a cookie header exceeds this size. The default, 4093, should be
+    #: safely `supported by most browsers <cookie_>`_. A cookie larger than
+    #: this size will still be sent, but it may be ignored or handled
+    #: incorrectly by some browsers. Set to 0 to disable this check.
+    #:
+    #: .. versionadded:: 0.13
+    #:
+    #: .. _`cookie`: http://browsercookielimits.squawky.net/
+    max_cookie_size = 4093
+
+    def __init__(
+        self,
+        response=None,
+        status=None,
+        headers=None,
+        mimetype=None,
+        content_type=None,
+        direct_passthrough=False,
+    ):
+        if isinstance(headers, Headers):
+            self.headers = headers
+        elif not headers:
+            self.headers = Headers()
+        else:
+            self.headers = Headers(headers)
+
+        if content_type is None:
+            if mimetype is None and "content-type" not in self.headers:
+                mimetype = self.default_mimetype
+            if mimetype is not None:
+                mimetype = get_content_type(mimetype, self.charset)
+            content_type = mimetype
+        if content_type is not None:
+            self.headers["Content-Type"] = content_type
+        if status is None:
+            status = self.default_status
+        if isinstance(status, integer_types):
+            self.status_code = status
+        else:
+            self.status = status
+
+        self.direct_passthrough = direct_passthrough
+        self._on_close = []
+
+        # we set the response after the headers so that if a class changes
+        # the charset attribute, the data is set in the correct charset.
+        if response is None:
+            self.response = []
+        elif isinstance(response, (text_type, bytes, bytearray)):
+            self.set_data(response)
+        else:
+            self.response = response
+
+    def call_on_close(self, func):
+        """Adds a function to the internal list of functions that should
+        be called as part of closing down the response.  Since 0.7 this
+        function also returns the function that was passed so that this
+        can be used as a decorator.
+
+        .. versionadded:: 0.6
+        """
+        self._on_close.append(func)
+        return func
+
+    def __repr__(self):
+        if self.is_sequence:
+            body_info = "%d bytes" % sum(map(len, self.iter_encoded()))
+        else:
+            body_info = "streamed" if self.is_streamed else "likely-streamed"
+        return "<%s %s [%s]>" % (self.__class__.__name__, body_info, self.status)
+
+    @classmethod
+    def force_type(cls, response, environ=None):
+        """Enforce that the WSGI response is a response object of the current
+        type.  Werkzeug will use the :class:`BaseResponse` internally in many
+        situations like the exceptions.  If you call :meth:`get_response` on an
+        exception you will get back a regular :class:`BaseResponse` object, even
+        if you are using a custom subclass.
+
+        This method can enforce a given response type, and it will also
+        convert arbitrary WSGI callables into response objects if an environ
+        is provided::
+
+            # convert a Werkzeug response object into an instance of the
+            # MyResponseClass subclass.
+            response = MyResponseClass.force_type(response)
+
+            # convert any WSGI application into a response object
+            response = MyResponseClass.force_type(response, environ)
+
+        This is especially useful if you want to post-process responses in
+        the main dispatcher and use functionality provided by your subclass.
+
+        Keep in mind that this will modify response objects in place if
+        possible!
+
+        :param response: a response object or wsgi application.
+        :param environ: a WSGI environment object.
+        :return: a response object.
+        """
+        if not isinstance(response, BaseResponse):
+            if environ is None:
+                raise TypeError(
+                    "cannot convert WSGI application into response"
+                    " objects without an environ"
+                )
+            response = BaseResponse(*_run_wsgi_app(response, environ))
+        response.__class__ = cls
+        return response
+
+    @classmethod
+    def from_app(cls, app, environ, buffered=False):
+        """Create a new response object from an application output.  This
+        works best if you pass it an application that returns a generator all
+        the time.  Sometimes applications may use the `write()` callable
+        returned by the `start_response` function.  This tries to resolve such
+        edge cases automatically.  But if you don't get the expected output
+        you should set `buffered` to `True` which enforces buffering.
+
+        :param app: the WSGI application to execute.
+        :param environ: the WSGI environment to execute against.
+        :param buffered: set to `True` to enforce buffering.
+        :return: a response object.
+        """
+        return cls(*_run_wsgi_app(app, environ, buffered))
+
+    def _get_status_code(self):
+        return self._status_code
+
+    def _set_status_code(self, code):
+        self._status_code = code
+        try:
+            self._status = "%d %s" % (code, HTTP_STATUS_CODES[code].upper())
+        except KeyError:
+            self._status = "%d UNKNOWN" % code
+
+    status_code = property(
+        _get_status_code, _set_status_code, doc="The HTTP Status code as number"
+    )
+    del _get_status_code, _set_status_code
+
+    def _get_status(self):
+        return self._status
+
+    def _set_status(self, value):
+        try:
+            self._status = to_native(value)
+        except AttributeError:
+            raise TypeError("Invalid status argument")
+
+        try:
+            self._status_code = int(self._status.split(None, 1)[0])
+        except ValueError:
+            self._status_code = 0
+            self._status = "0 %s" % self._status
+        except IndexError:
+            raise ValueError("Empty status argument")
+
+    status = property(_get_status, _set_status, doc="The HTTP Status code")
+    del _get_status, _set_status
+
+    def get_data(self, as_text=False):
+        """The string representation of the request body.  Whenever you call
+        this property the request iterable is encoded and flattened.  This
+        can lead to unwanted behavior if you stream big data.
+
+        This behavior can be disabled by setting
+        :attr:`implicit_sequence_conversion` to `False`.
+
+        If `as_text` is set to `True` the return value will be a decoded
+        unicode string.
+
+        .. versionadded:: 0.9
+        """
+        self._ensure_sequence()
+        rv = b"".join(self.iter_encoded())
+        if as_text:
+            rv = rv.decode(self.charset)
+        return rv
+
+    def set_data(self, value):
+        """Sets a new string as response.  The value set must either by a
+        unicode or bytestring.  If a unicode string is set it's encoded
+        automatically to the charset of the response (utf-8 by default).
+
+        .. versionadded:: 0.9
+        """
+        # if an unicode string is set, it's encoded directly so that we
+        # can set the content length
+        if isinstance(value, text_type):
+            value = value.encode(self.charset)
+        else:
+            value = bytes(value)
+        self.response = [value]
+        if self.automatically_set_content_length:
+            self.headers["Content-Length"] = str(len(value))
+
+    data = property(
+        get_data,
+        set_data,
+        doc="A descriptor that calls :meth:`get_data` and :meth:`set_data`.",
+    )
+
+    def calculate_content_length(self):
+        """Returns the content length if available or `None` otherwise."""
+        try:
+            self._ensure_sequence()
+        except RuntimeError:
+            return None
+        return sum(len(x) for x in self.iter_encoded())
+
+    def _ensure_sequence(self, mutable=False):
+        """This method can be called by methods that need a sequence.  If
+        `mutable` is true, it will also ensure that the response sequence
+        is a standard Python list.
+
+        .. versionadded:: 0.6
+        """
+        if self.is_sequence:
+            # if we need a mutable object, we ensure it's a list.
+            if mutable and not isinstance(self.response, list):
+                self.response = list(self.response)
+            return
+        if self.direct_passthrough:
+            raise RuntimeError(
+                "Attempted implicit sequence conversion but the"
+                " response object is in direct passthrough mode."
+            )
+        if not self.implicit_sequence_conversion:
+            raise RuntimeError(
+                "The response object required the iterable to be a"
+                " sequence, but the implicit conversion was disabled."
+                " Call make_sequence() yourself."
+            )
+        self.make_sequence()
+
+    def make_sequence(self):
+        """Converts the response iterator in a list.  By default this happens
+        automatically if required.  If `implicit_sequence_conversion` is
+        disabled, this method is not automatically called and some properties
+        might raise exceptions.  This also encodes all the items.
+
+        .. versionadded:: 0.6
+        """
+        if not self.is_sequence:
+            # if we consume an iterable we have to ensure that the close
+            # method of the iterable is called if available when we tear
+            # down the response
+            close = getattr(self.response, "close", None)
+            self.response = list(self.iter_encoded())
+            if close is not None:
+                self.call_on_close(close)
+
+    def iter_encoded(self):
+        """Iter the response encoded with the encoding of the response.
+        If the response object is invoked as WSGI application the return
+        value of this method is used as application iterator unless
+        :attr:`direct_passthrough` was activated.
+        """
+        if __debug__:
+            _warn_if_string(self.response)
+        # Encode in a separate function so that self.response is fetched
+        # early.  This allows us to wrap the response with the return
+        # value from get_app_iter or iter_encoded.
+        return _iter_encoded(self.response, self.charset)
+
+    def set_cookie(
+        self,
+        key,
+        value="",
+        max_age=None,
+        expires=None,
+        path="/",
+        domain=None,
+        secure=False,
+        httponly=False,
+        samesite=None,
+    ):
+        """Sets a cookie. The parameters are the same as in the cookie `Morsel`
+        object in the Python standard library but it accepts unicode data, too.
+
+        A warning is raised if the size of the cookie header exceeds
+        :attr:`max_cookie_size`, but the header will still be set.
+
+        :param key: the key (name) of the cookie to be set.
+        :param value: the value of the cookie.
+        :param max_age: should be a number of seconds, or `None` (default) if
+                        the cookie should last only as long as the client's
+                        browser session.
+        :param expires: should be a `datetime` object or UNIX timestamp.
+        :param path: limits the cookie to a given path, per default it will
+                     span the whole domain.
+        :param domain: if you want to set a cross-domain cookie.  For example,
+                       ``domain=".example.com"`` will set a cookie that is
+                       readable by the domain ``www.example.com``,
+                       ``foo.example.com`` etc.  Otherwise, a cookie will only
+                       be readable by the domain that set it.
+        :param secure: If `True`, the cookie will only be available via HTTPS
+        :param httponly: disallow JavaScript to access the cookie.  This is an
+                         extension to the cookie standard and probably not
+                         supported by all browsers.
+        :param samesite: Limits the scope of the cookie such that it will only
+                         be attached to requests if those requests are
+                         "same-site".
+        """
+        self.headers.add(
+            "Set-Cookie",
+            dump_cookie(
+                key,
+                value=value,
+                max_age=max_age,
+                expires=expires,
+                path=path,
+                domain=domain,
+                secure=secure,
+                httponly=httponly,
+                charset=self.charset,
+                max_size=self.max_cookie_size,
+                samesite=samesite,
+            ),
+        )
+
+    def delete_cookie(self, key, path="/", domain=None):
+        """Delete a cookie.  Fails silently if key doesn't exist.
+
+        :param key: the key (name) of the cookie to be deleted.
+        :param path: if the cookie that should be deleted was limited to a
+                     path, the path has to be defined here.
+        :param domain: if the cookie that should be deleted was limited to a
+                       domain, that domain has to be defined here.
+        """
+        self.set_cookie(key, expires=0, max_age=0, path=path, domain=domain)
+
+    @property
+    def is_streamed(self):
+        """If the response is streamed (the response is not an iterable with
+        a length information) this property is `True`.  In this case streamed
+        means that there is no information about the number of iterations.
+        This is usually `True` if a generator is passed to the response object.
+
+        This is useful for checking before applying some sort of post
+        filtering that should not take place for streamed responses.
+        """
+        try:
+            len(self.response)
+        except (TypeError, AttributeError):
+            return True
+        return False
+
+    @property
+    def is_sequence(self):
+        """If the iterator is buffered, this property will be `True`.  A
+        response object will consider an iterator to be buffered if the
+        response attribute is a list or tuple.
+
+        .. versionadded:: 0.6
+        """
+        return isinstance(self.response, (tuple, list))
+
+    def close(self):
+        """Close the wrapped response if possible.  You can also use the object
+        in a with statement which will automatically close it.
+
+        .. versionadded:: 0.9
+           Can now be used in a with statement.
+        """
+        if hasattr(self.response, "close"):
+            self.response.close()
+        for func in self._on_close:
+            func()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.close()
+
+    def freeze(self):
+        """Call this method if you want to make your response object ready for
+        being pickled.  This buffers the generator if there is one.  It will
+        also set the `Content-Length` header to the length of the body.
+
+        .. versionchanged:: 0.6
+           The `Content-Length` header is now set.
+        """
+        # we explicitly set the length to a list of the *encoded* response
+        # iterator.  Even if the implicit sequence conversion is disabled.
+        self.response = list(self.iter_encoded())
+        self.headers["Content-Length"] = str(sum(map(len, self.response)))
+
+    def get_wsgi_headers(self, environ):
+        """This is automatically called right before the response is started
+        and returns headers modified for the given environment.  It returns a
+        copy of the headers from the response with some modifications applied
+        if necessary.
+
+        For example the location header (if present) is joined with the root
+        URL of the environment.  Also the content length is automatically set
+        to zero here for certain status codes.
+
+        .. versionchanged:: 0.6
+           Previously that function was called `fix_headers` and modified
+           the response object in place.  Also since 0.6, IRIs in location
+           and content-location headers are handled properly.
+
+           Also starting with 0.6, Werkzeug will attempt to set the content
+           length if it is able to figure it out on its own.  This is the
+           case if all the strings in the response iterable are already
+           encoded and the iterable is buffered.
+
+        :param environ: the WSGI environment of the request.
+        :return: returns a new :class:`~werkzeug.datastructures.Headers`
+                 object.
+        """
+        headers = Headers(self.headers)
+        location = None
+        content_location = None
+        content_length = None
+        status = self.status_code
+
+        # iterate over the headers to find all values in one go.  Because
+        # get_wsgi_headers is used each response that gives us a tiny
+        # speedup.
+        for key, value in headers:
+            ikey = key.lower()
+            if ikey == u"location":
+                location = value
+            elif ikey == u"content-location":
+                content_location = value
+            elif ikey == u"content-length":
+                content_length = value
+
+        # make sure the location header is an absolute URL
+        if location is not None:
+            old_location = location
+            if isinstance(location, text_type):
+                # Safe conversion is necessary here as we might redirect
+                # to a broken URI scheme (for instance itms-services).
+                location = iri_to_uri(location, safe_conversion=True)
+
+            if self.autocorrect_location_header:
+                current_url = get_current_url(environ, strip_querystring=True)
+                if isinstance(current_url, text_type):
+                    current_url = iri_to_uri(current_url)
+                location = url_join(current_url, location)
+            if location != old_location:
+                headers["Location"] = location
+
+        # make sure the content location is a URL
+        if content_location is not None and isinstance(content_location, text_type):
+            headers["Content-Location"] = iri_to_uri(content_location)
+
+        if 100 <= status < 200 or status == 204:
+            # Per section 3.3.2 of RFC 7230, "a server MUST NOT send a
+            # Content-Length header field in any response with a status
+            # code of 1xx (Informational) or 204 (No Content)."
+            headers.remove("Content-Length")
+        elif status == 304:
+            remove_entity_headers(headers)
+
+        # if we can determine the content length automatically, we
+        # should try to do that.  But only if this does not involve
+        # flattening the iterator or encoding of unicode strings in
+        # the response.  We however should not do that if we have a 304
+        # response.
+        if (
+            self.automatically_set_content_length
+            and self.is_sequence
+            and content_length is None
+            and status not in (204, 304)
+            and not (100 <= status < 200)
+        ):
+            try:
+                content_length = sum(len(to_bytes(x, "ascii")) for x in self.response)
+            except UnicodeError:
+                # aha, something non-bytestringy in there, too bad, we
+                # can't safely figure out the length of the response.
+                pass
+            else:
+                headers["Content-Length"] = str(content_length)
+
+        return headers
+
+    def get_app_iter(self, environ):
+        """Returns the application iterator for the given environ.  Depending
+        on the request method and the current status code the return value
+        might be an empty response rather than the one from the response.
+
+        If the request method is `HEAD` or the status code is in a range
+        where the HTTP specification requires an empty response, an empty
+        iterable is returned.
+
+        .. versionadded:: 0.6
+
+        :param environ: the WSGI environment of the request.
+        :return: a response iterable.
+        """
+        status = self.status_code
+        if (
+            environ["REQUEST_METHOD"] == "HEAD"
+            or 100 <= status < 200
+            or status in (204, 304)
+        ):
+            iterable = ()
+        elif self.direct_passthrough:
+            if __debug__:
+                _warn_if_string(self.response)
+            return self.response
+        else:
+            iterable = self.iter_encoded()
+        return ClosingIterator(iterable, self.close)
+
+    def get_wsgi_response(self, environ):
+        """Returns the final WSGI response as tuple.  The first item in
+        the tuple is the application iterator, the second the status and
+        the third the list of headers.  The response returned is created
+        specially for the given environment.  For example if the request
+        method in the WSGI environment is ``'HEAD'`` the response will
+        be empty and only the headers and status code will be present.
+
+        .. versionadded:: 0.6
+
+        :param environ: the WSGI environment of the request.
+        :return: an ``(app_iter, status, headers)`` tuple.
+        """
+        headers = self.get_wsgi_headers(environ)
+        app_iter = self.get_app_iter(environ)
+        return app_iter, self.status, headers.to_wsgi_list()
+
+    def __call__(self, environ, start_response):
+        """Process this response as WSGI application.
+
+        :param environ: the WSGI environment.
+        :param start_response: the response callable provided by the WSGI
+                               server.
+        :return: an application iterator
+        """
+        app_iter, status, headers = self.get_wsgi_response(environ)
+        start_response(status, headers)
+        return app_iter
diff --git a/python/werkzeug/wrappers/common_descriptors.py b/python/werkzeug/wrappers/common_descriptors.py
new file mode 100644
index 0000000..e4107ee
--- /dev/null
+++ b/python/werkzeug/wrappers/common_descriptors.py
@@ -0,0 +1,322 @@
+from datetime import datetime
+from datetime import timedelta
+
+from .._compat import string_types
+from ..datastructures import CallbackDict
+from ..http import dump_age
+from ..http import dump_header
+from ..http import dump_options_header
+from ..http import http_date
+from ..http import parse_age
+from ..http import parse_date
+from ..http import parse_options_header
+from ..http import parse_set_header
+from ..utils import cached_property
+from ..utils import environ_property
+from ..utils import get_content_type
+from ..utils import header_property
+from ..wsgi import get_content_length
+
+
+class CommonRequestDescriptorsMixin(object):
+    """A mixin for :class:`BaseRequest` subclasses.  Request objects that
+    mix this class in will automatically get descriptors for a couple of
+    HTTP headers with automatic type conversion.
+
+    .. versionadded:: 0.5
+    """
+
+    content_type = environ_property(
+        "CONTENT_TYPE",
+        doc="""The Content-Type entity-header field indicates the media
+        type of the entity-body sent to the recipient or, in the case of
+        the HEAD method, the media type that would have been sent had
+        the request been a GET.""",
+    )
+
+    @cached_property
+    def content_length(self):
+        """The Content-Length entity-header field indicates the size of the
+        entity-body in bytes or, in the case of the HEAD method, the size of
+        the entity-body that would have been sent had the request been a
+        GET.
+        """
+        return get_content_length(self.environ)
+
+    content_encoding = environ_property(
+        "HTTP_CONTENT_ENCODING",
+        doc="""The Content-Encoding entity-header field is used as a
+        modifier to the media-type. When present, its value indicates
+        what additional content codings have been applied to the
+        entity-body, and thus what decoding mechanisms must be applied
+        in order to obtain the media-type referenced by the Content-Type
+        header field.
+
+        .. versionadded:: 0.9""",
+    )
+    content_md5 = environ_property(
+        "HTTP_CONTENT_MD5",
+        doc="""The Content-MD5 entity-header field, as defined in
+        RFC 1864, is an MD5 digest of the entity-body for the purpose of
+        providing an end-to-end message integrity check (MIC) of the
+        entity-body. (Note: a MIC is good for detecting accidental
+        modification of the entity-body in transit, but is not proof
+        against malicious attacks.)
+
+        .. versionadded:: 0.9""",
+    )
+    referrer = environ_property(
+        "HTTP_REFERER",
+        doc="""The Referer[sic] request-header field allows the client
+        to specify, for the server's benefit, the address (URI) of the
+        resource from which the Request-URI was obtained (the
+        "referrer", although the header field is misspelled).""",
+    )
+    date = environ_property(
+        "HTTP_DATE",
+        None,
+        parse_date,
+        doc="""The Date general-header field represents the date and
+        time at which the message was originated, having the same
+        semantics as orig-date in RFC 822.""",
+    )
+    max_forwards = environ_property(
+        "HTTP_MAX_FORWARDS",
+        None,
+        int,
+        doc="""The Max-Forwards request-header field provides a
+        mechanism with the TRACE and OPTIONS methods to limit the number
+        of proxies or gateways that can forward the request to the next
+        inbound server.""",
+    )
+
+    def _parse_content_type(self):
+        if not hasattr(self, "_parsed_content_type"):
+            self._parsed_content_type = parse_options_header(
+                self.environ.get("CONTENT_TYPE", "")
+            )
+
+    @property
+    def mimetype(self):
+        """Like :attr:`content_type`, but without parameters (eg, without
+        charset, type etc.) and always lowercase.  For example if the content
+        type is ``text/HTML; charset=utf-8`` the mimetype would be
+        ``'text/html'``.
+        """
+        self._parse_content_type()
+        return self._parsed_content_type[0].lower()
+
+    @property
+    def mimetype_params(self):
+        """The mimetype parameters as dict.  For example if the content
+        type is ``text/html; charset=utf-8`` the params would be
+        ``{'charset': 'utf-8'}``.
+        """
+        self._parse_content_type()
+        return self._parsed_content_type[1]
+
+    @cached_property
+    def pragma(self):
+        """The Pragma general-header field is used to include
+        implementation-specific directives that might apply to any recipient
+        along the request/response chain.  All pragma directives specify
+        optional behavior from the viewpoint of the protocol; however, some
+        systems MAY require that behavior be consistent with the directives.
+        """
+        return parse_set_header(self.environ.get("HTTP_PRAGMA", ""))
+
+
+class CommonResponseDescriptorsMixin(object):
+    """A mixin for :class:`BaseResponse` subclasses.  Response objects that
+    mix this class in will automatically get descriptors for a couple of
+    HTTP headers with automatic type conversion.
+    """
+
+    @property
+    def mimetype(self):
+        """The mimetype (content type without charset etc.)"""
+        ct = self.headers.get("content-type")
+        if ct:
+            return ct.split(";")[0].strip()
+
+    @mimetype.setter
+    def mimetype(self, value):
+        self.headers["Content-Type"] = get_content_type(value, self.charset)
+
+    @property
+    def mimetype_params(self):
+        """The mimetype parameters as dict. For example if the
+        content type is ``text/html; charset=utf-8`` the params would be
+        ``{'charset': 'utf-8'}``.
+
+        .. versionadded:: 0.5
+        """
+
+        def on_update(d):
+            self.headers["Content-Type"] = dump_options_header(self.mimetype, d)
+
+        d = parse_options_header(self.headers.get("content-type", ""))[1]
+        return CallbackDict(d, on_update)
+
+    location = header_property(
+        "Location",
+        doc="""The Location response-header field is used to redirect
+        the recipient to a location other than the Request-URI for
+        completion of the request or identification of a new
+        resource.""",
+    )
+    age = header_property(
+        "Age",
+        None,
+        parse_age,
+        dump_age,
+        doc="""The Age response-header field conveys the sender's
+        estimate of the amount of time since the response (or its
+        revalidation) was generated at the origin server.
+
+        Age values are non-negative decimal integers, representing time
+        in seconds.""",
+    )
+    content_type = header_property(
+        "Content-Type",
+        doc="""The Content-Type entity-header field indicates the media
+        type of the entity-body sent to the recipient or, in the case of
+        the HEAD method, the media type that would have been sent had
+        the request been a GET.""",
+    )
+    content_length = header_property(
+        "Content-Length",
+        None,
+        int,
+        str,
+        doc="""The Content-Length entity-header field indicates the size
+        of the entity-body, in decimal number of OCTETs, sent to the
+        recipient or, in the case of the HEAD method, the size of the
+        entity-body that would have been sent had the request been a
+        GET.""",
+    )
+    content_location = header_property(
+        "Content-Location",
+        doc="""The Content-Location entity-header field MAY be used to
+        supply the resource location for the entity enclosed in the
+        message when that entity is accessible from a location separate
+        from the requested resource's URI.""",
+    )
+    content_encoding = header_property(
+        "Content-Encoding",
+        doc="""The Content-Encoding entity-header field is used as a
+        modifier to the media-type. When present, its value indicates
+        what additional content codings have been applied to the
+        entity-body, and thus what decoding mechanisms must be applied
+        in order to obtain the media-type referenced by the Content-Type
+        header field.""",
+    )
+    content_md5 = header_property(
+        "Content-MD5",
+        doc="""The Content-MD5 entity-header field, as defined in
+        RFC 1864, is an MD5 digest of the entity-body for the purpose of
+        providing an end-to-end message integrity check (MIC) of the
+        entity-body. (Note: a MIC is good for detecting accidental
+        modification of the entity-body in transit, but is not proof
+        against malicious attacks.)""",
+    )
+    date = header_property(
+        "Date",
+        None,
+        parse_date,
+        http_date,
+        doc="""The Date general-header field represents the date and
+        time at which the message was originated, having the same
+        semantics as orig-date in RFC 822.""",
+    )
+    expires = header_property(
+        "Expires",
+        None,
+        parse_date,
+        http_date,
+        doc="""The Expires entity-header field gives the date/time after
+        which the response is considered stale. A stale cache entry may
+        not normally be returned by a cache.""",
+    )
+    last_modified = header_property(
+        "Last-Modified",
+        None,
+        parse_date,
+        http_date,
+        doc="""The Last-Modified entity-header field indicates the date
+        and time at which the origin server believes the variant was
+        last modified.""",
+    )
+
+    @property
+    def retry_after(self):
+        """The Retry-After response-header field can be used with a
+        503 (Service Unavailable) response to indicate how long the
+        service is expected to be unavailable to the requesting client.
+
+        Time in seconds until expiration or date.
+        """
+        value = self.headers.get("retry-after")
+        if value is None:
+            return
+        elif value.isdigit():
+            return datetime.utcnow() + timedelta(seconds=int(value))
+        return parse_date(value)
+
+    @retry_after.setter
+    def retry_after(self, value):
+        if value is None:
+            if "retry-after" in self.headers:
+                del self.headers["retry-after"]
+            return
+        elif isinstance(value, datetime):
+            value = http_date(value)
+        else:
+            value = str(value)
+        self.headers["Retry-After"] = value
+
+    def _set_property(name, doc=None):  # noqa: B902
+        def fget(self):
+            def on_update(header_set):
+                if not header_set and name in self.headers:
+                    del self.headers[name]
+                elif header_set:
+                    self.headers[name] = header_set.to_header()
+
+            return parse_set_header(self.headers.get(name), on_update)
+
+        def fset(self, value):
+            if not value:
+                del self.headers[name]
+            elif isinstance(value, string_types):
+                self.headers[name] = value
+            else:
+                self.headers[name] = dump_header(value)
+
+        return property(fget, fset, doc=doc)
+
+    vary = _set_property(
+        "Vary",
+        doc="""The Vary field value indicates the set of request-header
+        fields that fully determines, while the response is fresh,
+        whether a cache is permitted to use the response to reply to a
+        subsequent request without revalidation.""",
+    )
+    content_language = _set_property(
+        "Content-Language",
+        doc="""The Content-Language entity-header field describes the
+        natural language(s) of the intended audience for the enclosed
+        entity. Note that this might not be equivalent to all the
+        languages used within the entity-body.""",
+    )
+    allow = _set_property(
+        "Allow",
+        doc="""The Allow entity-header field lists the set of methods
+        supported by the resource identified by the Request-URI. The
+        purpose of this field is strictly to inform the recipient of
+        valid methods associated with the resource. An Allow header
+        field MUST be present in a 405 (Method Not Allowed)
+        response.""",
+    )
+
+    del _set_property
diff --git a/python/werkzeug/wrappers/etag.py b/python/werkzeug/wrappers/etag.py
new file mode 100644
index 0000000..0733506
--- /dev/null
+++ b/python/werkzeug/wrappers/etag.py
@@ -0,0 +1,304 @@
+from .._compat import string_types
+from .._internal import _get_environ
+from ..datastructures import ContentRange
+from ..datastructures import RequestCacheControl
+from ..datastructures import ResponseCacheControl
+from ..http import generate_etag
+from ..http import http_date
+from ..http import is_resource_modified
+from ..http import parse_cache_control_header
+from ..http import parse_content_range_header
+from ..http import parse_date
+from ..http import parse_etags
+from ..http import parse_if_range_header
+from ..http import parse_range_header
+from ..http import quote_etag
+from ..http import unquote_etag
+from ..utils import cached_property
+from ..utils import header_property
+from ..wrappers.base_response import _clean_accept_ranges
+from ..wsgi import _RangeWrapper
+
+
+class ETagRequestMixin(object):
+    """Add entity tag and cache descriptors to a request object or object with
+    a WSGI environment available as :attr:`~BaseRequest.environ`.  This not
+    only provides access to etags but also to the cache control header.
+    """
+
+    @cached_property
+    def cache_control(self):
+        """A :class:`~werkzeug.datastructures.RequestCacheControl` object
+        for the incoming cache control headers.
+        """
+        cache_control = self.environ.get("HTTP_CACHE_CONTROL")
+        return parse_cache_control_header(cache_control, None, RequestCacheControl)
+
+    @cached_property
+    def if_match(self):
+        """An object containing all the etags in the `If-Match` header.
+
+        :rtype: :class:`~werkzeug.datastructures.ETags`
+        """
+        return parse_etags(self.environ.get("HTTP_IF_MATCH"))
+
+    @cached_property
+    def if_none_match(self):
+        """An object containing all the etags in the `If-None-Match` header.
+
+        :rtype: :class:`~werkzeug.datastructures.ETags`
+        """
+        return parse_etags(self.environ.get("HTTP_IF_NONE_MATCH"))
+
+    @cached_property
+    def if_modified_since(self):
+        """The parsed `If-Modified-Since` header as datetime object."""
+        return parse_date(self.environ.get("HTTP_IF_MODIFIED_SINCE"))
+
+    @cached_property
+    def if_unmodified_since(self):
+        """The parsed `If-Unmodified-Since` header as datetime object."""
+        return parse_date(self.environ.get("HTTP_IF_UNMODIFIED_SINCE"))
+
+    @cached_property
+    def if_range(self):
+        """The parsed `If-Range` header.
+
+        .. versionadded:: 0.7
+
+        :rtype: :class:`~werkzeug.datastructures.IfRange`
+        """
+        return parse_if_range_header(self.environ.get("HTTP_IF_RANGE"))
+
+    @cached_property
+    def range(self):
+        """The parsed `Range` header.
+
+        .. versionadded:: 0.7
+
+        :rtype: :class:`~werkzeug.datastructures.Range`
+        """
+        return parse_range_header(self.environ.get("HTTP_RANGE"))
+
+
+class ETagResponseMixin(object):
+    """Adds extra functionality to a response object for etag and cache
+    handling.  This mixin requires an object with at least a `headers`
+    object that implements a dict like interface similar to
+    :class:`~werkzeug.datastructures.Headers`.
+
+    If you want the :meth:`freeze` method to automatically add an etag, you
+    have to mixin this method before the response base class.  The default
+    response class does not do that.
+    """
+
+    @property
+    def cache_control(self):
+        """The Cache-Control general-header field is used to specify
+        directives that MUST be obeyed by all caching mechanisms along the
+        request/response chain.
+        """
+
+        def on_update(cache_control):
+            if not cache_control and "cache-control" in self.headers:
+                del self.headers["cache-control"]
+            elif cache_control:
+                self.headers["Cache-Control"] = cache_control.to_header()
+
+        return parse_cache_control_header(
+            self.headers.get("cache-control"), on_update, ResponseCacheControl
+        )
+
+    def _wrap_response(self, start, length):
+        """Wrap existing Response in case of Range Request context."""
+        if self.status_code == 206:
+            self.response = _RangeWrapper(self.response, start, length)
+
+    def _is_range_request_processable(self, environ):
+        """Return ``True`` if `Range` header is present and if underlying
+        resource is considered unchanged when compared with `If-Range` header.
+        """
+        return (
+            "HTTP_IF_RANGE" not in environ
+            or not is_resource_modified(
+                environ,
+                self.headers.get("etag"),
+                None,
+                self.headers.get("last-modified"),
+                ignore_if_range=False,
+            )
+        ) and "HTTP_RANGE" in environ
+
+    def _process_range_request(self, environ, complete_length=None, accept_ranges=None):
+        """Handle Range Request related headers (RFC7233).  If `Accept-Ranges`
+        header is valid, and Range Request is processable, we set the headers
+        as described by the RFC, and wrap the underlying response in a
+        RangeWrapper.
+
+        Returns ``True`` if Range Request can be fulfilled, ``False`` otherwise.
+
+        :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable`
+                 if `Range` header could not be parsed or satisfied.
+        """
+        from ..exceptions import RequestedRangeNotSatisfiable
+
+        if accept_ranges is None:
+            return False
+        self.headers["Accept-Ranges"] = accept_ranges
+        if not self._is_range_request_processable(environ) or complete_length is None:
+            return False
+        parsed_range = parse_range_header(environ.get("HTTP_RANGE"))
+        if parsed_range is None:
+            raise RequestedRangeNotSatisfiable(complete_length)
+        range_tuple = parsed_range.range_for_length(complete_length)
+        content_range_header = parsed_range.to_content_range_header(complete_length)
+        if range_tuple is None or content_range_header is None:
+            raise RequestedRangeNotSatisfiable(complete_length)
+        content_length = range_tuple[1] - range_tuple[0]
+        # Be sure not to send 206 response
+        # if requested range is the full content.
+        if content_length != complete_length:
+            self.headers["Content-Length"] = content_length
+            self.content_range = content_range_header
+            self.status_code = 206
+            self._wrap_response(range_tuple[0], content_length)
+            return True
+        return False
+
+    def make_conditional(
+        self, request_or_environ, accept_ranges=False, complete_length=None
+    ):
+        """Make the response conditional to the request.  This method works
+        best if an etag was defined for the response already.  The `add_etag`
+        method can be used to do that.  If called without etag just the date
+        header is set.
+
+        This does nothing if the request method in the request or environ is
+        anything but GET or HEAD.
+
+        For optimal performance when handling range requests, it's recommended
+        that your response data object implements `seekable`, `seek` and `tell`
+        methods as described by :py:class:`io.IOBase`.  Objects returned by
+        :meth:`~werkzeug.wsgi.wrap_file` automatically implement those methods.
+
+        It does not remove the body of the response because that's something
+        the :meth:`__call__` function does for us automatically.
+
+        Returns self so that you can do ``return resp.make_conditional(req)``
+        but modifies the object in-place.
+
+        :param request_or_environ: a request object or WSGI environment to be
+                                   used to make the response conditional
+                                   against.
+        :param accept_ranges: This parameter dictates the value of
+                              `Accept-Ranges` header. If ``False`` (default),
+                              the header is not set. If ``True``, it will be set
+                              to ``"bytes"``. If ``None``, it will be set to
+                              ``"none"``. If it's a string, it will use this
+                              value.
+        :param complete_length: Will be used only in valid Range Requests.
+                                It will set `Content-Range` complete length
+                                value and compute `Content-Length` real value.
+                                This parameter is mandatory for successful
+                                Range Requests completion.
+        :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable`
+                 if `Range` header could not be parsed or satisfied.
+        """
+        environ = _get_environ(request_or_environ)
+        if environ["REQUEST_METHOD"] in ("GET", "HEAD"):
+            # if the date is not in the headers, add it now.  We however
+            # will not override an already existing header.  Unfortunately
+            # this header will be overriden by many WSGI servers including
+            # wsgiref.
+            if "date" not in self.headers:
+                self.headers["Date"] = http_date()
+            accept_ranges = _clean_accept_ranges(accept_ranges)
+            is206 = self._process_range_request(environ, complete_length, accept_ranges)
+            if not is206 and not is_resource_modified(
+                environ,
+                self.headers.get("etag"),
+                None,
+                self.headers.get("last-modified"),
+            ):
+                if parse_etags(environ.get("HTTP_IF_MATCH")):
+                    self.status_code = 412
+                else:
+                    self.status_code = 304
+            if (
+                self.automatically_set_content_length
+                and "content-length" not in self.headers
+            ):
+                length = self.calculate_content_length()
+                if length is not None:
+                    self.headers["Content-Length"] = length
+        return self
+
+    def add_etag(self, overwrite=False, weak=False):
+        """Add an etag for the current response if there is none yet."""
+        if overwrite or "etag" not in self.headers:
+            self.set_etag(generate_etag(self.get_data()), weak)
+
+    def set_etag(self, etag, weak=False):
+        """Set the etag, and override the old one if there was one."""
+        self.headers["ETag"] = quote_etag(etag, weak)
+
+    def get_etag(self):
+        """Return a tuple in the form ``(etag, is_weak)``.  If there is no
+        ETag the return value is ``(None, None)``.
+        """
+        return unquote_etag(self.headers.get("ETag"))
+
+    def freeze(self, no_etag=False):
+        """Call this method if you want to make your response object ready for
+        pickeling.  This buffers the generator if there is one.  This also
+        sets the etag unless `no_etag` is set to `True`.
+        """
+        if not no_etag:
+            self.add_etag()
+        super(ETagResponseMixin, self).freeze()
+
+    accept_ranges = header_property(
+        "Accept-Ranges",
+        doc="""The `Accept-Ranges` header. Even though the name would
+        indicate that multiple values are supported, it must be one
+        string token only.
+
+        The values ``'bytes'`` and ``'none'`` are common.
+
+        .. versionadded:: 0.7""",
+    )
+
+    def _get_content_range(self):
+        def on_update(rng):
+            if not rng:
+                del self.headers["content-range"]
+            else:
+                self.headers["Content-Range"] = rng.to_header()
+
+        rv = parse_content_range_header(self.headers.get("content-range"), on_update)
+        # always provide a content range object to make the descriptor
+        # more user friendly.  It provides an unset() method that can be
+        # used to remove the header quickly.
+        if rv is None:
+            rv = ContentRange(None, None, None, on_update=on_update)
+        return rv
+
+    def _set_content_range(self, value):
+        if not value:
+            del self.headers["content-range"]
+        elif isinstance(value, string_types):
+            self.headers["Content-Range"] = value
+        else:
+            self.headers["Content-Range"] = value.to_header()
+
+    content_range = property(
+        _get_content_range,
+        _set_content_range,
+        doc="""The ``Content-Range`` header as
+        :class:`~werkzeug.datastructures.ContentRange` object. Even if
+        the header is not set it wil provide such an object for easier
+        manipulation.
+
+        .. versionadded:: 0.7""",
+    )
+    del _get_content_range, _set_content_range
diff --git a/python/werkzeug/wrappers/json.py b/python/werkzeug/wrappers/json.py
new file mode 100644
index 0000000..6d5dc33
--- /dev/null
+++ b/python/werkzeug/wrappers/json.py
@@ -0,0 +1,145 @@
+from __future__ import absolute_import
+
+import datetime
+import uuid
+
+from .._compat import text_type
+from ..exceptions import BadRequest
+from ..utils import detect_utf_encoding
+
+try:
+    import simplejson as _json
+except ImportError:
+    import json as _json
+
+
+class _JSONModule(object):
+    @staticmethod
+    def _default(o):
+        if isinstance(o, datetime.date):
+            return o.isoformat()
+
+        if isinstance(o, uuid.UUID):
+            return str(o)
+
+        if hasattr(o, "__html__"):
+            return text_type(o.__html__())
+
+        raise TypeError()
+
+    @classmethod
+    def dumps(cls, obj, **kw):
+        kw.setdefault("separators", (",", ":"))
+        kw.setdefault("default", cls._default)
+        kw.setdefault("sort_keys", True)
+        return _json.dumps(obj, **kw)
+
+    @staticmethod
+    def loads(s, **kw):
+        if isinstance(s, bytes):
+            # Needed for Python < 3.6
+            encoding = detect_utf_encoding(s)
+            s = s.decode(encoding)
+
+        return _json.loads(s, **kw)
+
+
+class JSONMixin(object):
+    """Mixin to parse :attr:`data` as JSON. Can be mixed in for both
+    :class:`~werkzeug.wrappers.Request` and
+    :class:`~werkzeug.wrappers.Response` classes.
+
+    If `simplejson`_ is installed it is preferred over Python's built-in
+    :mod:`json` module.
+
+    .. _simplejson: https://simplejson.readthedocs.io/en/latest/
+    """
+
+    #: A module or other object that has ``dumps`` and ``loads``
+    #: functions that match the API of the built-in :mod:`json` module.
+    json_module = _JSONModule
+
+    @property
+    def json(self):
+        """The parsed JSON data if :attr:`mimetype` indicates JSON
+        (:mimetype:`application/json`, see :meth:`is_json`).
+
+        Calls :meth:`get_json` with default arguments.
+        """
+        return self.get_json()
+
+    @property
+    def is_json(self):
+        """Check if the mimetype indicates JSON data, either
+        :mimetype:`application/json` or :mimetype:`application/*+json`.
+        """
+        mt = self.mimetype
+        return (
+            mt == "application/json"
+            or mt.startswith("application/")
+            and mt.endswith("+json")
+        )
+
+    def _get_data_for_json(self, cache):
+        try:
+            return self.get_data(cache=cache)
+        except TypeError:
+            # Response doesn't have cache param.
+            return self.get_data()
+
+    # Cached values for ``(silent=False, silent=True)``. Initialized
+    # with sentinel values.
+    _cached_json = (Ellipsis, Ellipsis)
+
+    def get_json(self, force=False, silent=False, cache=True):
+        """Parse :attr:`data` as JSON.
+
+        If the mimetype does not indicate JSON
+        (:mimetype:`application/json`, see :meth:`is_json`), this
+        returns ``None``.
+
+        If parsing fails, :meth:`on_json_loading_failed` is called and
+        its return value is used as the return value.
+
+        :param force: Ignore the mimetype and always try to parse JSON.
+        :param silent: Silence parsing errors and return ``None``
+            instead.
+        :param cache: Store the parsed JSON to return for subsequent
+            calls.
+        """
+        if cache and self._cached_json[silent] is not Ellipsis:
+            return self._cached_json[silent]
+
+        if not (force or self.is_json):
+            return None
+
+        data = self._get_data_for_json(cache=cache)
+
+        try:
+            rv = self.json_module.loads(data)
+        except ValueError as e:
+            if silent:
+                rv = None
+
+                if cache:
+                    normal_rv, _ = self._cached_json
+                    self._cached_json = (normal_rv, rv)
+            else:
+                rv = self.on_json_loading_failed(e)
+
+                if cache:
+                    _, silent_rv = self._cached_json
+                    self._cached_json = (rv, silent_rv)
+        else:
+            if cache:
+                self._cached_json = (rv, rv)
+
+        return rv
+
+    def on_json_loading_failed(self, e):
+        """Called if :meth:`get_json` parsing fails and isn't silenced.
+        If this method returns a value, it is used as the return value
+        for :meth:`get_json`. The default implementation raises
+        :exc:`~werkzeug.exceptions.BadRequest`.
+        """
+        raise BadRequest("Failed to decode JSON object: {0}".format(e))
diff --git a/python/werkzeug/wrappers/request.py b/python/werkzeug/wrappers/request.py
new file mode 100644
index 0000000..d1c71b6
--- /dev/null
+++ b/python/werkzeug/wrappers/request.py
@@ -0,0 +1,44 @@
+from .accept import AcceptMixin
+from .auth import AuthorizationMixin
+from .base_request import BaseRequest
+from .common_descriptors import CommonRequestDescriptorsMixin
+from .etag import ETagRequestMixin
+from .user_agent import UserAgentMixin
+
+
+class Request(
+    BaseRequest,
+    AcceptMixin,
+    ETagRequestMixin,
+    UserAgentMixin,
+    AuthorizationMixin,
+    CommonRequestDescriptorsMixin,
+):
+    """Full featured request object implementing the following mixins:
+
+    - :class:`AcceptMixin` for accept header parsing
+    - :class:`ETagRequestMixin` for etag and cache control handling
+    - :class:`UserAgentMixin` for user agent introspection
+    - :class:`AuthorizationMixin` for http auth handling
+    - :class:`CommonRequestDescriptorsMixin` for common headers
+    """
+
+
+class StreamOnlyMixin(object):
+    """If mixed in before the request object this will change the bahavior
+    of it to disable handling of form parsing.  This disables the
+    :attr:`files`, :attr:`form` attributes and will just provide a
+    :attr:`stream` attribute that however is always available.
+
+    .. versionadded:: 0.9
+    """
+
+    disable_data_descriptor = True
+    want_form_data_parsed = False
+
+
+class PlainRequest(StreamOnlyMixin, Request):
+    """A request object without special form parsing capabilities.
+
+    .. versionadded:: 0.9
+    """
diff --git a/python/werkzeug/wrappers/response.py b/python/werkzeug/wrappers/response.py
new file mode 100644
index 0000000..cd86cac
--- /dev/null
+++ b/python/werkzeug/wrappers/response.py
@@ -0,0 +1,78 @@
+from ..utils import cached_property
+from .auth import WWWAuthenticateMixin
+from .base_response import BaseResponse
+from .common_descriptors import CommonResponseDescriptorsMixin
+from .etag import ETagResponseMixin
+
+
+class ResponseStream(object):
+    """A file descriptor like object used by the :class:`ResponseStreamMixin` to
+    represent the body of the stream.  It directly pushes into the response
+    iterable of the response object.
+    """
+
+    mode = "wb+"
+
+    def __init__(self, response):
+        self.response = response
+        self.closed = False
+
+    def write(self, value):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        self.response._ensure_sequence(mutable=True)
+        self.response.response.append(value)
+        self.response.headers.pop("Content-Length", None)
+        return len(value)
+
+    def writelines(self, seq):
+        for item in seq:
+            self.write(item)
+
+    def close(self):
+        self.closed = True
+
+    def flush(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+
+    def isatty(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        return False
+
+    def tell(self):
+        self.response._ensure_sequence()
+        return sum(map(len, self.response.response))
+
+    @property
+    def encoding(self):
+        return self.response.charset
+
+
+class ResponseStreamMixin(object):
+    """Mixin for :class:`BaseRequest` subclasses.  Classes that inherit from
+    this mixin will automatically get a :attr:`stream` property that provides
+    a write-only interface to the response iterable.
+    """
+
+    @cached_property
+    def stream(self):
+        """The response iterable as write-only stream."""
+        return ResponseStream(self)
+
+
+class Response(
+    BaseResponse,
+    ETagResponseMixin,
+    ResponseStreamMixin,
+    CommonResponseDescriptorsMixin,
+    WWWAuthenticateMixin,
+):
+    """Full featured response object implementing the following mixins:
+
+    - :class:`ETagResponseMixin` for etag and cache control handling
+    - :class:`ResponseStreamMixin` to add support for the `stream` property
+    - :class:`CommonResponseDescriptorsMixin` for various HTTP descriptors
+    - :class:`WWWAuthenticateMixin` for HTTP authentication support
+    """
diff --git a/python/werkzeug/wrappers/user_agent.py b/python/werkzeug/wrappers/user_agent.py
new file mode 100644
index 0000000..72588dd
--- /dev/null
+++ b/python/werkzeug/wrappers/user_agent.py
@@ -0,0 +1,15 @@
+from ..utils import cached_property
+
+
+class UserAgentMixin(object):
+    """Adds a `user_agent` attribute to the request object which
+    contains the parsed user agent of the browser that triggered the
+    request as a :class:`~werkzeug.useragents.UserAgent` object.
+    """
+
+    @cached_property
+    def user_agent(self):
+        """The current user agent."""
+        from ..useragents import UserAgent
+
+        return UserAgent(self.environ)
diff --git a/python/werkzeug/wsgi.py b/python/werkzeug/wsgi.py
new file mode 100644
index 0000000..f069f2d
--- /dev/null
+++ b/python/werkzeug/wsgi.py
@@ -0,0 +1,1067 @@
+# -*- coding: utf-8 -*-
+"""
+    werkzeug.wsgi
+    ~~~~~~~~~~~~~
+
+    This module implements WSGI related helpers.
+
+    :copyright: 2007 Pallets
+    :license: BSD-3-Clause
+"""
+import io
+import re
+import warnings
+from functools import partial
+from functools import update_wrapper
+from itertools import chain
+
+from ._compat import BytesIO
+from ._compat import implements_iterator
+from ._compat import make_literal_wrapper
+from ._compat import string_types
+from ._compat import text_type
+from ._compat import to_bytes
+from ._compat import to_unicode
+from ._compat import try_coerce_native
+from ._compat import wsgi_get_bytes
+from ._internal import _encode_idna
+from .urls import uri_to_iri
+from .urls import url_join
+from .urls import url_parse
+from .urls import url_quote
+
+
+def responder(f):
+    """Marks a function as responder.  Decorate a function with it and it
+    will automatically call the return value as WSGI application.
+
+    Example::
+
+        @responder
+        def application(environ, start_response):
+            return Response('Hello World!')
+    """
+    return update_wrapper(lambda *a: f(*a)(*a[-2:]), f)
+
+
+def get_current_url(
+    environ,
+    root_only=False,
+    strip_querystring=False,
+    host_only=False,
+    trusted_hosts=None,
+):
+    """A handy helper function that recreates the full URL as IRI for the
+    current request or parts of it.  Here's an example:
+
+    >>> from werkzeug.test import create_environ
+    >>> env = create_environ("/?param=foo", "http://localhost/script")
+    >>> get_current_url(env)
+    'http://localhost/script/?param=foo'
+    >>> get_current_url(env, root_only=True)
+    'http://localhost/script/'
+    >>> get_current_url(env, host_only=True)
+    'http://localhost/'
+    >>> get_current_url(env, strip_querystring=True)
+    'http://localhost/script/'
+
+    This optionally it verifies that the host is in a list of trusted hosts.
+    If the host is not in there it will raise a
+    :exc:`~werkzeug.exceptions.SecurityError`.
+
+    Note that the string returned might contain unicode characters as the
+    representation is an IRI not an URI.  If you need an ASCII only
+    representation you can use the :func:`~werkzeug.urls.iri_to_uri`
+    function:
+
+    >>> from werkzeug.urls import iri_to_uri
+    >>> iri_to_uri(get_current_url(env))
+    'http://localhost/script/?param=foo'
+
+    :param environ: the WSGI environment to get the current URL from.
+    :param root_only: set `True` if you only want the root URL.
+    :param strip_querystring: set to `True` if you don't want the querystring.
+    :param host_only: set to `True` if the host URL should be returned.
+    :param trusted_hosts: a list of trusted hosts, see :func:`host_is_trusted`
+                          for more information.
+    """
+    tmp = [environ["wsgi.url_scheme"], "://", get_host(environ, trusted_hosts)]
+    cat = tmp.append
+    if host_only:
+        return uri_to_iri("".join(tmp) + "/")
+    cat(url_quote(wsgi_get_bytes(environ.get("SCRIPT_NAME", ""))).rstrip("/"))
+    cat("/")
+    if not root_only:
+        cat(url_quote(wsgi_get_bytes(environ.get("PATH_INFO", "")).lstrip(b"/")))
+        if not strip_querystring:
+            qs = get_query_string(environ)
+            if qs:
+                cat("?" + qs)
+    return uri_to_iri("".join(tmp))
+
+
+def host_is_trusted(hostname, trusted_list):
+    """Checks if a host is trusted against a list.  This also takes care
+    of port normalization.
+
+    .. versionadded:: 0.9
+
+    :param hostname: the hostname to check
+    :param trusted_list: a list of hostnames to check against.  If a
+                         hostname starts with a dot it will match against
+                         all subdomains as well.
+    """
+    if not hostname:
+        return False
+
+    if isinstance(trusted_list, string_types):
+        trusted_list = [trusted_list]
+
+    def _normalize(hostname):
+        if ":" in hostname:
+            hostname = hostname.rsplit(":", 1)[0]
+        return _encode_idna(hostname)
+
+    try:
+        hostname = _normalize(hostname)
+    except UnicodeError:
+        return False
+    for ref in trusted_list:
+        if ref.startswith("."):
+            ref = ref[1:]
+            suffix_match = True
+        else:
+            suffix_match = False
+        try:
+            ref = _normalize(ref)
+        except UnicodeError:
+            return False
+        if ref == hostname:
+            return True
+        if suffix_match and hostname.endswith(b"." + ref):
+            return True
+    return False
+
+
+def get_host(environ, trusted_hosts=None):
+    """Return the host for the given WSGI environment. This first checks
+    the ``Host`` header. If it's not present, then ``SERVER_NAME`` and
+    ``SERVER_PORT`` are used. The host will only contain the port if it
+    is different than the standard port for the protocol.
+
+    Optionally, verify that the host is trusted using
+    :func:`host_is_trusted` and raise a
+    :exc:`~werkzeug.exceptions.SecurityError` if it is not.
+
+    :param environ: The WSGI environment to get the host from.
+    :param trusted_hosts: A list of trusted hosts.
+    :return: Host, with port if necessary.
+    :raise ~werkzeug.exceptions.SecurityError: If the host is not
+        trusted.
+    """
+    if "HTTP_HOST" in environ:
+        rv = environ["HTTP_HOST"]
+        if environ["wsgi.url_scheme"] == "http" and rv.endswith(":80"):
+            rv = rv[:-3]
+        elif environ["wsgi.url_scheme"] == "https" and rv.endswith(":443"):
+            rv = rv[:-4]
+    else:
+        rv = environ["SERVER_NAME"]
+        if (environ["wsgi.url_scheme"], environ["SERVER_PORT"]) not in (
+            ("https", "443"),
+            ("http", "80"),
+        ):
+            rv += ":" + environ["SERVER_PORT"]
+    if trusted_hosts is not None:
+        if not host_is_trusted(rv, trusted_hosts):
+            from .exceptions import SecurityError
+
+            raise SecurityError('Host "%s" is not trusted' % rv)
+    return rv
+
+
+def get_content_length(environ):
+    """Returns the content length from the WSGI environment as
+    integer. If it's not available or chunked transfer encoding is used,
+    ``None`` is returned.
+
+    .. versionadded:: 0.9
+
+    :param environ: the WSGI environ to fetch the content length from.
+    """
+    if environ.get("HTTP_TRANSFER_ENCODING", "") == "chunked":
+        return None
+
+    content_length = environ.get("CONTENT_LENGTH")
+    if content_length is not None:
+        try:
+            return max(0, int(content_length))
+        except (ValueError, TypeError):
+            pass
+
+
+def get_input_stream(environ, safe_fallback=True):
+    """Returns the input stream from the WSGI environment and wraps it
+    in the most sensible way possible. The stream returned is not the
+    raw WSGI stream in most cases but one that is safe to read from
+    without taking into account the content length.
+
+    If content length is not set, the stream will be empty for safety reasons.
+    If the WSGI server supports chunked or infinite streams, it should set
+    the ``wsgi.input_terminated`` value in the WSGI environ to indicate that.
+
+    .. versionadded:: 0.9
+
+    :param environ: the WSGI environ to fetch the stream from.
+    :param safe_fallback: use an empty stream as a safe fallback when the
+        content length is not set. Disabling this allows infinite streams,
+        which can be a denial-of-service risk.
+    """
+    stream = environ["wsgi.input"]
+    content_length = get_content_length(environ)
+
+    # A wsgi extension that tells us if the input is terminated.  In
+    # that case we return the stream unchanged as we know we can safely
+    # read it until the end.
+    if environ.get("wsgi.input_terminated"):
+        return stream
+
+    # If the request doesn't specify a content length, returning the stream is
+    # potentially dangerous because it could be infinite, malicious or not. If
+    # safe_fallback is true, return an empty stream instead for safety.
+    if content_length is None:
+        return BytesIO() if safe_fallback else stream
+
+    # Otherwise limit the stream to the content length
+    return LimitedStream(stream, content_length)
+
+
+def get_query_string(environ):
+    """Returns the `QUERY_STRING` from the WSGI environment.  This also takes
+    care about the WSGI decoding dance on Python 3 environments as a
+    native string.  The string returned will be restricted to ASCII
+    characters.
+
+    .. versionadded:: 0.9
+
+    :param environ: the WSGI environment object to get the query string from.
+    """
+    qs = wsgi_get_bytes(environ.get("QUERY_STRING", ""))
+    # QUERY_STRING really should be ascii safe but some browsers
+    # will send us some unicode stuff (I am looking at you IE).
+    # In that case we want to urllib quote it badly.
+    return try_coerce_native(url_quote(qs, safe=":&%=+$!*'(),"))
+
+
+def get_path_info(environ, charset="utf-8", errors="replace"):
+    """Returns the `PATH_INFO` from the WSGI environment and properly
+    decodes it.  This also takes care about the WSGI decoding dance
+    on Python 3 environments.  if the `charset` is set to `None` a
+    bytestring is returned.
+
+    .. versionadded:: 0.9
+
+    :param environ: the WSGI environment object to get the path from.
+    :param charset: the charset for the path info, or `None` if no
+                    decoding should be performed.
+    :param errors: the decoding error handling.
+    """
+    path = wsgi_get_bytes(environ.get("PATH_INFO", ""))
+    return to_unicode(path, charset, errors, allow_none_charset=True)
+
+
+def get_script_name(environ, charset="utf-8", errors="replace"):
+    """Returns the `SCRIPT_NAME` from the WSGI environment and properly
+    decodes it.  This also takes care about the WSGI decoding dance
+    on Python 3 environments.  if the `charset` is set to `None` a
+    bytestring is returned.
+
+    .. versionadded:: 0.9
+
+    :param environ: the WSGI environment object to get the path from.
+    :param charset: the charset for the path, or `None` if no
+                    decoding should be performed.
+    :param errors: the decoding error handling.
+    """
+    path = wsgi_get_bytes(environ.get("SCRIPT_NAME", ""))
+    return to_unicode(path, charset, errors, allow_none_charset=True)
+
+
+def pop_path_info(environ, charset="utf-8", errors="replace"):
+    """Removes and returns the next segment of `PATH_INFO`, pushing it onto
+    `SCRIPT_NAME`.  Returns `None` if there is nothing left on `PATH_INFO`.
+
+    If the `charset` is set to `None` a bytestring is returned.
+
+    If there are empty segments (``'/foo//bar``) these are ignored but
+    properly pushed to the `SCRIPT_NAME`:
+
+    >>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}
+    >>> pop_path_info(env)
+    'a'
+    >>> env['SCRIPT_NAME']
+    '/foo/a'
+    >>> pop_path_info(env)
+    'b'
+    >>> env['SCRIPT_NAME']
+    '/foo/a/b'
+
+    .. versionadded:: 0.5
+
+    .. versionchanged:: 0.9
+       The path is now decoded and a charset and encoding
+       parameter can be provided.
+
+    :param environ: the WSGI environment that is modified.
+    """
+    path = environ.get("PATH_INFO")
+    if not path:
+        return None
+
+    script_name = environ.get("SCRIPT_NAME", "")
+
+    # shift multiple leading slashes over
+    old_path = path
+    path = path.lstrip("/")
+    if path != old_path:
+        script_name += "/" * (len(old_path) - len(path))
+
+    if "/" not in path:
+        environ["PATH_INFO"] = ""
+        environ["SCRIPT_NAME"] = script_name + path
+        rv = wsgi_get_bytes(path)
+    else:
+        segment, path = path.split("/", 1)
+        environ["PATH_INFO"] = "/" + path
+        environ["SCRIPT_NAME"] = script_name + segment
+        rv = wsgi_get_bytes(segment)
+
+    return to_unicode(rv, charset, errors, allow_none_charset=True)
+
+
+def peek_path_info(environ, charset="utf-8", errors="replace"):
+    """Returns the next segment on the `PATH_INFO` or `None` if there
+    is none.  Works like :func:`pop_path_info` without modifying the
+    environment:
+
+    >>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}
+    >>> peek_path_info(env)
+    'a'
+    >>> peek_path_info(env)
+    'a'
+
+    If the `charset` is set to `None` a bytestring is returned.
+
+    .. versionadded:: 0.5
+
+    .. versionchanged:: 0.9
+       The path is now decoded and a charset and encoding
+       parameter can be provided.
+
+    :param environ: the WSGI environment that is checked.
+    """
+    segments = environ.get("PATH_INFO", "").lstrip("/").split("/", 1)
+    if segments:
+        return to_unicode(
+            wsgi_get_bytes(segments[0]), charset, errors, allow_none_charset=True
+        )
+
+
+def extract_path_info(
+    environ_or_baseurl,
+    path_or_url,
+    charset="utf-8",
+    errors="werkzeug.url_quote",
+    collapse_http_schemes=True,
+):
+    """Extracts the path info from the given URL (or WSGI environment) and
+    path.  The path info returned is a unicode string, not a bytestring
+    suitable for a WSGI environment.  The URLs might also be IRIs.
+
+    If the path info could not be determined, `None` is returned.
+
+    Some examples:
+
+    >>> extract_path_info('http://example.com/app', '/app/hello')
+    u'/hello'
+    >>> extract_path_info('http://example.com/app',
+    ...                   'https://example.com/app/hello')
+    u'/hello'
+    >>> extract_path_info('http://example.com/app',
+    ...                   'https://example.com/app/hello',
+    ...                   collapse_http_schemes=False) is None
+    True
+
+    Instead of providing a base URL you can also pass a WSGI environment.
+
+    :param environ_or_baseurl: a WSGI environment dict, a base URL or
+                               base IRI.  This is the root of the
+                               application.
+    :param path_or_url: an absolute path from the server root, a
+                        relative path (in which case it's the path info)
+                        or a full URL.  Also accepts IRIs and unicode
+                        parameters.
+    :param charset: the charset for byte data in URLs
+    :param errors: the error handling on decode
+    :param collapse_http_schemes: if set to `False` the algorithm does
+                                  not assume that http and https on the
+                                  same server point to the same
+                                  resource.
+
+    .. versionchanged:: 0.15
+        The ``errors`` parameter defaults to leaving invalid bytes
+        quoted instead of replacing them.
+
+    .. versionadded:: 0.6
+    """
+
+    def _normalize_netloc(scheme, netloc):
+        parts = netloc.split(u"@", 1)[-1].split(u":", 1)
+        if len(parts) == 2:
+            netloc, port = parts
+            if (scheme == u"http" and port == u"80") or (
+                scheme == u"https" and port == u"443"
+            ):
+                port = None
+        else:
+            netloc = parts[0]
+            port = None
+        if port is not None:
+            netloc += u":" + port
+        return netloc
+
+    # make sure whatever we are working on is a IRI and parse it
+    path = uri_to_iri(path_or_url, charset, errors)
+    if isinstance(environ_or_baseurl, dict):
+        environ_or_baseurl = get_current_url(environ_or_baseurl, root_only=True)
+    base_iri = uri_to_iri(environ_or_baseurl, charset, errors)
+    base_scheme, base_netloc, base_path = url_parse(base_iri)[:3]
+    cur_scheme, cur_netloc, cur_path, = url_parse(url_join(base_iri, path))[:3]
+
+    # normalize the network location
+    base_netloc = _normalize_netloc(base_scheme, base_netloc)
+    cur_netloc = _normalize_netloc(cur_scheme, cur_netloc)
+
+    # is that IRI even on a known HTTP scheme?
+    if collapse_http_schemes:
+        for scheme in base_scheme, cur_scheme:
+            if scheme not in (u"http", u"https"):
+                return None
+    else:
+        if not (base_scheme in (u"http", u"https") and base_scheme == cur_scheme):
+            return None
+
+    # are the netlocs compatible?
+    if base_netloc != cur_netloc:
+        return None
+
+    # are we below the application path?
+    base_path = base_path.rstrip(u"/")
+    if not cur_path.startswith(base_path):
+        return None
+
+    return u"/" + cur_path[len(base_path) :].lstrip(u"/")
+
+
+@implements_iterator
+class ClosingIterator(object):
+    """The WSGI specification requires that all middlewares and gateways
+    respect the `close` callback of the iterable returned by the application.
+    Because it is useful to add another close action to a returned iterable
+    and adding a custom iterable is a boring task this class can be used for
+    that::
+
+        return ClosingIterator(app(environ, start_response), [cleanup_session,
+                                                              cleanup_locals])
+
+    If there is just one close function it can be passed instead of the list.
+
+    A closing iterator is not needed if the application uses response objects
+    and finishes the processing if the response is started::
+
+        try:
+            return response(environ, start_response)
+        finally:
+            cleanup_session()
+            cleanup_locals()
+    """
+
+    def __init__(self, iterable, callbacks=None):
+        iterator = iter(iterable)
+        self._next = partial(next, iterator)
+        if callbacks is None:
+            callbacks = []
+        elif callable(callbacks):
+            callbacks = [callbacks]
+        else:
+            callbacks = list(callbacks)
+        iterable_close = getattr(iterable, "close", None)
+        if iterable_close:
+            callbacks.insert(0, iterable_close)
+        self._callbacks = callbacks
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self._next()
+
+    def close(self):
+        for callback in self._callbacks:
+            callback()
+
+
+def wrap_file(environ, file, buffer_size=8192):
+    """Wraps a file.  This uses the WSGI server's file wrapper if available
+    or otherwise the generic :class:`FileWrapper`.
+
+    .. versionadded:: 0.5
+
+    If the file wrapper from the WSGI server is used it's important to not
+    iterate over it from inside the application but to pass it through
+    unchanged.  If you want to pass out a file wrapper inside a response
+    object you have to set :attr:`~BaseResponse.direct_passthrough` to `True`.
+
+    More information about file wrappers are available in :pep:`333`.
+
+    :param file: a :class:`file`-like object with a :meth:`~file.read` method.
+    :param buffer_size: number of bytes for one iteration.
+    """
+    return environ.get("wsgi.file_wrapper", FileWrapper)(file, buffer_size)
+
+
+@implements_iterator
+class FileWrapper(object):
+    """This class can be used to convert a :class:`file`-like object into
+    an iterable.  It yields `buffer_size` blocks until the file is fully
+    read.
+
+    You should not use this class directly but rather use the
+    :func:`wrap_file` function that uses the WSGI server's file wrapper
+    support if it's available.
+
+    .. versionadded:: 0.5
+
+    If you're using this object together with a :class:`BaseResponse` you have
+    to use the `direct_passthrough` mode.
+
+    :param file: a :class:`file`-like object with a :meth:`~file.read` method.
+    :param buffer_size: number of bytes for one iteration.
+    """
+
+    def __init__(self, file, buffer_size=8192):
+        self.file = file
+        self.buffer_size = buffer_size
+
+    def close(self):
+        if hasattr(self.file, "close"):
+            self.file.close()
+
+    def seekable(self):
+        if hasattr(self.file, "seekable"):
+            return self.file.seekable()
+        if hasattr(self.file, "seek"):
+            return True
+        return False
+
+    def seek(self, *args):
+        if hasattr(self.file, "seek"):
+            self.file.seek(*args)
+
+    def tell(self):
+        if hasattr(self.file, "tell"):
+            return self.file.tell()
+        return None
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        data = self.file.read(self.buffer_size)
+        if data:
+            return data
+        raise StopIteration()
+
+
+@implements_iterator
+class _RangeWrapper(object):
+    # private for now, but should we make it public in the future ?
+
+    """This class can be used to convert an iterable object into
+    an iterable that will only yield a piece of the underlying content.
+    It yields blocks until the underlying stream range is fully read.
+    The yielded blocks will have a size that can't exceed the original
+    iterator defined block size, but that can be smaller.
+
+    If you're using this object together with a :class:`BaseResponse` you have
+    to use the `direct_passthrough` mode.
+
+    :param iterable: an iterable object with a :meth:`__next__` method.
+    :param start_byte: byte from which read will start.
+    :param byte_range: how many bytes to read.
+    """
+
+    def __init__(self, iterable, start_byte=0, byte_range=None):
+        self.iterable = iter(iterable)
+        self.byte_range = byte_range
+        self.start_byte = start_byte
+        self.end_byte = None
+        if byte_range is not None:
+            self.end_byte = self.start_byte + self.byte_range
+        self.read_length = 0
+        self.seekable = hasattr(iterable, "seekable") and iterable.seekable()
+        self.end_reached = False
+
+    def __iter__(self):
+        return self
+
+    def _next_chunk(self):
+        try:
+            chunk = next(self.iterable)
+            self.read_length += len(chunk)
+            return chunk
+        except StopIteration:
+            self.end_reached = True
+            raise
+
+    def _first_iteration(self):
+        chunk = None
+        if self.seekable:
+            self.iterable.seek(self.start_byte)
+            self.read_length = self.iterable.tell()
+            contextual_read_length = self.read_length
+        else:
+            while self.read_length <= self.start_byte:
+                chunk = self._next_chunk()
+            if chunk is not None:
+                chunk = chunk[self.start_byte - self.read_length :]
+            contextual_read_length = self.start_byte
+        return chunk, contextual_read_length
+
+    def _next(self):
+        if self.end_reached:
+            raise StopIteration()
+        chunk = None
+        contextual_read_length = self.read_length
+        if self.read_length == 0:
+            chunk, contextual_read_length = self._first_iteration()
+        if chunk is None:
+            chunk = self._next_chunk()
+        if self.end_byte is not None and self.read_length >= self.end_byte:
+            self.end_reached = True
+            return chunk[: self.end_byte - contextual_read_length]
+        return chunk
+
+    def __next__(self):
+        chunk = self._next()
+        if chunk:
+            return chunk
+        self.end_reached = True
+        raise StopIteration()
+
+    def close(self):
+        if hasattr(self.iterable, "close"):
+            self.iterable.close()
+
+
+def _make_chunk_iter(stream, limit, buffer_size):
+    """Helper for the line and chunk iter functions."""
+    if isinstance(stream, (bytes, bytearray, text_type)):
+        raise TypeError(
+            "Passed a string or byte object instead of true iterator or stream."
+        )
+    if not hasattr(stream, "read"):
+        for item in stream:
+            if item:
+                yield item
+        return
+    if not isinstance(stream, LimitedStream) and limit is not None:
+        stream = LimitedStream(stream, limit)
+    _read = stream.read
+    while 1:
+        item = _read(buffer_size)
+        if not item:
+            break
+        yield item
+
+
+def make_line_iter(stream, limit=None, buffer_size=10 * 1024, cap_at_buffer=False):
+    """Safely iterates line-based over an input stream.  If the input stream
+    is not a :class:`LimitedStream` the `limit` parameter is mandatory.
+
+    This uses the stream's :meth:`~file.read` method internally as opposite
+    to the :meth:`~file.readline` method that is unsafe and can only be used
+    in violation of the WSGI specification.  The same problem applies to the
+    `__iter__` function of the input stream which calls :meth:`~file.readline`
+    without arguments.
+
+    If you need line-by-line processing it's strongly recommended to iterate
+    over the input stream using this helper function.
+
+    .. versionchanged:: 0.8
+       This function now ensures that the limit was reached.
+
+    .. versionadded:: 0.9
+       added support for iterators as input stream.
+
+    .. versionadded:: 0.11.10
+       added support for the `cap_at_buffer` parameter.
+
+    :param stream: the stream or iterate to iterate over.
+    :param limit: the limit in bytes for the stream.  (Usually
+                  content length.  Not necessary if the `stream`
+                  is a :class:`LimitedStream`.
+    :param buffer_size: The optional buffer size.
+    :param cap_at_buffer: if this is set chunks are split if they are longer
+                          than the buffer size.  Internally this is implemented
+                          that the buffer size might be exhausted by a factor
+                          of two however.
+    """
+    _iter = _make_chunk_iter(stream, limit, buffer_size)
+
+    first_item = next(_iter, "")
+    if not first_item:
+        return
+
+    s = make_literal_wrapper(first_item)
+    empty = s("")
+    cr = s("\r")
+    lf = s("\n")
+    crlf = s("\r\n")
+
+    _iter = chain((first_item,), _iter)
+
+    def _iter_basic_lines():
+        _join = empty.join
+        buffer = []
+        while 1:
+            new_data = next(_iter, "")
+            if not new_data:
+                break
+            new_buf = []
+            buf_size = 0
+            for item in chain(buffer, new_data.splitlines(True)):
+                new_buf.append(item)
+                buf_size += len(item)
+                if item and item[-1:] in crlf:
+                    yield _join(new_buf)
+                    new_buf = []
+                elif cap_at_buffer and buf_size >= buffer_size:
+                    rv = _join(new_buf)
+                    while len(rv) >= buffer_size:
+                        yield rv[:buffer_size]
+                        rv = rv[buffer_size:]
+                    new_buf = [rv]
+            buffer = new_buf
+        if buffer:
+            yield _join(buffer)
+
+    # This hackery is necessary to merge 'foo\r' and '\n' into one item
+    # of 'foo\r\n' if we were unlucky and we hit a chunk boundary.
+    previous = empty
+    for item in _iter_basic_lines():
+        if item == lf and previous[-1:] == cr:
+            previous += item
+            item = empty
+        if previous:
+            yield previous
+        previous = item
+    if previous:
+        yield previous
+
+
+def make_chunk_iter(
+    stream, separator, limit=None, buffer_size=10 * 1024, cap_at_buffer=False
+):
+    """Works like :func:`make_line_iter` but accepts a separator
+    which divides chunks.  If you want newline based processing
+    you should use :func:`make_line_iter` instead as it
+    supports arbitrary newline markers.
+
+    .. versionadded:: 0.8
+
+    .. versionadded:: 0.9
+       added support for iterators as input stream.
+
+    .. versionadded:: 0.11.10
+       added support for the `cap_at_buffer` parameter.
+
+    :param stream: the stream or iterate to iterate over.
+    :param separator: the separator that divides chunks.
+    :param limit: the limit in bytes for the stream.  (Usually
+                  content length.  Not necessary if the `stream`
+                  is otherwise already limited).
+    :param buffer_size: The optional buffer size.
+    :param cap_at_buffer: if this is set chunks are split if they are longer
+                          than the buffer size.  Internally this is implemented
+                          that the buffer size might be exhausted by a factor
+                          of two however.
+    """
+    _iter = _make_chunk_iter(stream, limit, buffer_size)
+
+    first_item = next(_iter, "")
+    if not first_item:
+        return
+
+    _iter = chain((first_item,), _iter)
+    if isinstance(first_item, text_type):
+        separator = to_unicode(separator)
+        _split = re.compile(r"(%s)" % re.escape(separator)).split
+        _join = u"".join
+    else:
+        separator = to_bytes(separator)
+        _split = re.compile(b"(" + re.escape(separator) + b")").split
+        _join = b"".join
+
+    buffer = []
+    while 1:
+        new_data = next(_iter, "")
+        if not new_data:
+            break
+        chunks = _split(new_data)
+        new_buf = []
+        buf_size = 0
+        for item in chain(buffer, chunks):
+            if item == separator:
+                yield _join(new_buf)
+                new_buf = []
+                buf_size = 0
+            else:
+                buf_size += len(item)
+                new_buf.append(item)
+
+                if cap_at_buffer and buf_size >= buffer_size:
+                    rv = _join(new_buf)
+                    while len(rv) >= buffer_size:
+                        yield rv[:buffer_size]
+                        rv = rv[buffer_size:]
+                    new_buf = [rv]
+                    buf_size = len(rv)
+
+        buffer = new_buf
+    if buffer:
+        yield _join(buffer)
+
+
+@implements_iterator
+class LimitedStream(io.IOBase):
+    """Wraps a stream so that it doesn't read more than n bytes.  If the
+    stream is exhausted and the caller tries to get more bytes from it
+    :func:`on_exhausted` is called which by default returns an empty
+    string.  The return value of that function is forwarded
+    to the reader function.  So if it returns an empty string
+    :meth:`read` will return an empty string as well.
+
+    The limit however must never be higher than what the stream can
+    output.  Otherwise :meth:`readlines` will try to read past the
+    limit.
+
+    .. admonition:: Note on WSGI compliance
+
+       calls to :meth:`readline` and :meth:`readlines` are not
+       WSGI compliant because it passes a size argument to the
+       readline methods.  Unfortunately the WSGI PEP is not safely
+       implementable without a size argument to :meth:`readline`
+       because there is no EOF marker in the stream.  As a result
+       of that the use of :meth:`readline` is discouraged.
+
+       For the same reason iterating over the :class:`LimitedStream`
+       is not portable.  It internally calls :meth:`readline`.
+
+       We strongly suggest using :meth:`read` only or using the
+       :func:`make_line_iter` which safely iterates line-based
+       over a WSGI input stream.
+
+    :param stream: the stream to wrap.
+    :param limit: the limit for the stream, must not be longer than
+                  what the string can provide if the stream does not
+                  end with `EOF` (like `wsgi.input`)
+    """
+
+    def __init__(self, stream, limit):
+        self._read = stream.read
+        self._readline = stream.readline
+        self._pos = 0
+        self.limit = limit
+
+    def __iter__(self):
+        return self
+
+    @property
+    def is_exhausted(self):
+        """If the stream is exhausted this attribute is `True`."""
+        return self._pos >= self.limit
+
+    def on_exhausted(self):
+        """This is called when the stream tries to read past the limit.
+        The return value of this function is returned from the reading
+        function.
+        """
+        # Read null bytes from the stream so that we get the
+        # correct end of stream marker.
+        return self._read(0)
+
+    def on_disconnect(self):
+        """What should happen if a disconnect is detected?  The return
+        value of this function is returned from read functions in case
+        the client went away.  By default a
+        :exc:`~werkzeug.exceptions.ClientDisconnected` exception is raised.
+        """
+        from .exceptions import ClientDisconnected
+
+        raise ClientDisconnected()
+
+    def exhaust(self, chunk_size=1024 * 64):
+        """Exhaust the stream.  This consumes all the data left until the
+        limit is reached.
+
+        :param chunk_size: the size for a chunk.  It will read the chunk
+                           until the stream is exhausted and throw away
+                           the results.
+        """
+        to_read = self.limit - self._pos
+        chunk = chunk_size
+        while to_read > 0:
+            chunk = min(to_read, chunk)
+            self.read(chunk)
+            to_read -= chunk
+
+    def read(self, size=None):
+        """Read `size` bytes or if size is not provided everything is read.
+
+        :param size: the number of bytes read.
+        """
+        if self._pos >= self.limit:
+            return self.on_exhausted()
+        if size is None or size == -1:  # -1 is for consistence with file
+            size = self.limit
+        to_read = min(self.limit - self._pos, size)
+        try:
+            read = self._read(to_read)
+        except (IOError, ValueError):
+            return self.on_disconnect()
+        if to_read and len(read) != to_read:
+            return self.on_disconnect()
+        self._pos += len(read)
+        return read
+
+    def readline(self, size=None):
+        """Reads one line from the stream."""
+        if self._pos >= self.limit:
+            return self.on_exhausted()
+        if size is None:
+            size = self.limit - self._pos
+        else:
+            size = min(size, self.limit - self._pos)
+        try:
+            line = self._readline(size)
+        except (ValueError, IOError):
+            return self.on_disconnect()
+        if size and not line:
+            return self.on_disconnect()
+        self._pos += len(line)
+        return line
+
+    def readlines(self, size=None):
+        """Reads a file into a list of strings.  It calls :meth:`readline`
+        until the file is read to the end.  It does support the optional
+        `size` argument if the underlaying stream supports it for
+        `readline`.
+        """
+        last_pos = self._pos
+        result = []
+        if size is not None:
+            end = min(self.limit, last_pos + size)
+        else:
+            end = self.limit
+        while 1:
+            if size is not None:
+                size -= last_pos - self._pos
+            if self._pos >= end:
+                break
+            result.append(self.readline(size))
+            if size is not None:
+                last_pos = self._pos
+        return result
+
+    def tell(self):
+        """Returns the position of the stream.
+
+        .. versionadded:: 0.9
+        """
+        return self._pos
+
+    def __next__(self):
+        line = self.readline()
+        if not line:
+            raise StopIteration()
+        return line
+
+    def readable(self):
+        return True
+
+
+# DEPRECATED
+from .middleware.dispatcher import DispatcherMiddleware as _DispatcherMiddleware
+from .middleware.http_proxy import ProxyMiddleware as _ProxyMiddleware
+from .middleware.shared_data import SharedDataMiddleware as _SharedDataMiddleware
+
+
+class ProxyMiddleware(_ProxyMiddleware):
+    """
+    .. deprecated:: 0.15
+        ``werkzeug.wsgi.ProxyMiddleware`` has moved to
+        :mod:`werkzeug.middleware.http_proxy`. This import will be
+        removed in 1.0.
+    """
+
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.wsgi.ProxyMiddleware' has moved to 'werkzeug"
+            ".middleware.http_proxy.ProxyMiddleware'. This import is"
+            " deprecated as of version 0.15 and will be removed in"
+            " version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(ProxyMiddleware, self).__init__(*args, **kwargs)
+
+
+class SharedDataMiddleware(_SharedDataMiddleware):
+    """
+    .. deprecated:: 0.15
+        ``werkzeug.wsgi.SharedDataMiddleware`` has moved to
+        :mod:`werkzeug.middleware.shared_data`. This import will be
+        removed in 1.0.
+    """
+
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.wsgi.SharedDataMiddleware' has moved to"
+            " 'werkzeug.middleware.shared_data.SharedDataMiddleware'."
+            " This import is deprecated as of version 0.15 and will be"
+            " removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(SharedDataMiddleware, self).__init__(*args, **kwargs)
+
+
+class DispatcherMiddleware(_DispatcherMiddleware):
+    """
+    .. deprecated:: 0.15
+        ``werkzeug.wsgi.DispatcherMiddleware`` has moved to
+        :mod:`werkzeug.middleware.dispatcher`. This import will be
+        removed in 1.0.
+    """
+
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            "'werkzeug.wsgi.DispatcherMiddleware' has moved to"
+            " 'werkzeug.middleware.dispatcher.DispatcherMiddleware'."
+            " This import is deprecated as of version 0.15 and will be"
+            " removed in version 1.0.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        super(DispatcherMiddleware, self).__init__(*args, **kwargs)
diff --git a/server.py b/server.py
index 3f400a3..917be79 100644
--- a/server.py
+++ b/server.py
@@ -2,9 +2,12 @@ from gevent import monkey
 monkey.patch_all()
 import gevent.socket
 
-from youtube.youtube import youtube
+from youtube import yt_app
 from youtube import util
-import http_errors
+
+# these are just so the files get run - they import yt_app and add routes to it
+from youtube import watch
+
 import settings
 
 from gevent.pywsgi import WSGIServer
@@ -22,7 +25,7 @@ def youtu_be(env, start_response):
     id = env['PATH_INFO'][1:]
     env['PATH_INFO'] = '/watch'
     env['QUERY_STRING'] = 'v=' + id
-    return youtube(env, start_response)
+    yield from yt_app(env, start_response)
 
 def proxy_site(env, start_response):
     headers = {
@@ -41,10 +44,10 @@ def proxy_site(env, start_response):
         headers = headers.items()
 
     start_response('200 OK', headers )
-    return content
+    yield content
 
 site_handlers = {
-    'youtube.com':youtube,
+    'youtube.com':yt_app,
     'youtu.be':youtu_be,
     'ytimg.com': proxy_site,
     'yt3.ggpht.com': proxy_site,
@@ -96,12 +99,12 @@ def site_dispatch(env, start_response):
             except KeyError:
                 continue
             else:
-                yield handler(env, start_response)
+                yield from handler(env, start_response)
                 break
         else:   # did not break
             yield error_code('404 Not Found', start_response)
             return
-
+        '''
     except http_errors.Code200 as e:    # Raised in scenarios where a simple status message is to be returned, such as a terminated channel
         start_response('200 OK', ())
         yield str(e).encode('utf-8')
@@ -118,7 +121,7 @@ def site_dispatch(env, start_response):
         start_response('502 Bad Gateway', ())
         print(str(e))
         yield b'502 Bad Gateway'
-        
+        '''
     except Exception:
         start_response('500 Internal Server Error', ())
         yield b'500 Internal Server Error'
diff --git a/youtube/__init__.py b/youtube/__init__.py
new file mode 100644
index 0000000..0df56d1
--- /dev/null
+++ b/youtube/__init__.py
@@ -0,0 +1,2 @@
+import flask
+yt_app = flask.Flask(__name__)
\ No newline at end of file
diff --git a/youtube/comments.css b/youtube/static/comments.css
index 4cec3e1..4cec3e1 100644
--- a/youtube/comments.css
+++ b/youtube/static/comments.css
diff --git a/youtube/favicon.ico b/youtube/static/favicon.ico
index 9d6417c..9d6417c 100644
--- a/youtube/favicon.ico
+++ b/youtube/static/favicon.ico
diff --git a/youtube/shared.css b/youtube/static/shared.css
index 1b25d7f..1b25d7f 100644
--- a/youtube/shared.css
+++ b/youtube/static/shared.css
diff --git a/youtube/templates/error.html b/youtube/templates/error.html
new file mode 100644
index 0000000..f253807
--- /dev/null
+++ b/youtube/templates/error.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <meta charset="utf-8">
+        <title>Error</title>
+        <link href="/youtube.com/shared.css" type="text/css" rel="stylesheet">
+        <link href="/youtube.com/comments.css" type="text/css" rel="stylesheet">
+        <link href="/youtube.com/favicon.ico" type="image/x-icon" rel="icon">
+        <link title="Youtube local" href="/youtube.com/opensearch.xml" rel="search" type="application/opensearchdescription+xml">
+    </head>
+    <body>
+{{ header|safe }}
+        <main>
+{{ error_message }}
+        </main>
+    </body>
+</html>
diff --git a/yt_watch_template.html b/youtube/templates/watch.html
index 59b588a..7e83306 100644
--- a/yt_watch_template.html
+++ b/youtube/templates/watch.html
@@ -2,10 +2,10 @@
 <html>
     <head>
         <meta charset="utf-8">
-        <title>$page_title</title>
-        <link href="/youtube.com/shared.css" type="text/css" rel="stylesheet">
-        <link href="/youtube.com/comments.css" type="text/css" rel="stylesheet">
-        <link href="/youtube.com/favicon.ico" type="image/x-icon" rel="icon">
+        <title>{{ title }}</title>
+        <link href="/youtube.com/static/shared.css" type="text/css" rel="stylesheet">
+        <link href="/youtube.com/static/comments.css" type="text/css" rel="stylesheet">
+        <link href="/youtube.com/static/favicon.ico" type="image/x-icon" rel="icon">
         <link title="Youtube local" href="/youtube.com/opensearch.xml" rel="search" type="application/opensearchdescription+xml">
         <style type="text/css">
             main{
@@ -153,52 +153,70 @@
         </style>
     </head>
     <body>
-$header
+{{ header|safe }}
         <main>
                 <div id="left">
                 </div>
-                <article class="full-item">          
+                <article class="full-item">
 
                     <video width="640" height="360" controls autofocus>
-$video_sources
-                    </video>
+{% for video_source in video_sources %}
+                        <source src="{{ video_source['src'] }}" type="{{ video_source['type'] }}">
+{% endfor %}
+
+{% for source in subtitle_sources %}
+    {% if source['on'] %}
+                        <track label="{{ source['label'] }}" src="{{ source['url'] }}" kind="subtitles" srclang="{{ source['srclang'] }}" default>
+    {% else %}
+                        <track label="{{ source['label'] }}" src="{{ source['url'] }}" kind="subtitles" srclang="{{ source['srclang'] }}">
+    {% endif %}
+{% endfor %}
 
-                    <h2 class="title">$video_title</h2>
-$is_unlisted
+                    </video>
 
-                    <address>Uploaded by <a href="$uploader_channel_url">$uploader</a></address>
-                    <span class="views">$views views</span>
+                    <h2 class="title">{{ title }}</h2>
+{% if unlisted %}
+                    <span class="is-unlisted">Unlisted</span>
+{% endif %}
+                    <address>Uploaded by <a href="{{ uploader_channel_url }}">{{ uploader }}</a></address>
+                    <span class="views">{{ views }} views</span>
 
 
-                    <time datetime="$upload_date">Published on $upload_date</time>
-                    <span class="likes-dislikes">$likes likes $dislikes dislikes</span>
+                    <time datetime="$upload_date">Published on {{ upload_date }}</time>
+                    <span class="likes-dislikes">{{ likes }} likes {{ dislikes }} dislikes</span>
                     <div class="download-dropdown">
                         <button class="download-dropdown-label">Download</button>
                         <div class="download-dropdown-content">
-$download_options
+{% for format in download_formats %}
+                            <a href="{{ format['url'] }}">
+                                <span>{{ format['ext'] }}</span>
+                                <span>{{ format['resolution'] }}</span>
+                                <span>{{ format['note'] }}</span>
+                            </a>
+{% endfor  %}
                         </div>
                     </div>
-                    <input class="checkbox" name="video_info_list" value="$video_info" form="playlist-edit" type="checkbox">
+                    <input class="checkbox" name="video_info_list" value="{{ video_info }}" form="playlist-edit" type="checkbox">
 
-                    <span class="description">$description</span>
+                    <span class="description">{{ description }}</span>
                     <div class="music-list">
-$music_list
+{{ music_list|safe }}
                     </div>
-$comments
+{{ comments|safe }}
                 </article>
 
-            
-            
+
+
 
                 <nav id="related">
-$related
+{{ related|safe }}
                 </nav>
 
         </main>
-    
-    
-    
-    
-    
+
+
+
+
+
     </body>
 </html>
diff --git a/youtube/watch.py b/youtube/watch.py
index 06b525a..48fd7e3 100644
--- a/youtube/watch.py
+++ b/youtube/watch.py
@@ -1,127 +1,17 @@
+from youtube import yt_app
 from youtube import util, html_common, comments
+import settings
+
+from flask import request
+import flask
 
 from youtube_dl.YoutubeDL import YoutubeDL
 from youtube_dl.extractor.youtube import YoutubeError
 import json
-import urllib
-from string import Template
 import html
-
 import gevent
-import settings
 import os
 
-video_height_priority = (360, 480, 240, 720, 1080)
-
-
-_formats = {
-    '5': {'ext': 'flv', 'width': 400, 'height': 240, 'acodec': 'mp3', 'abr': 64, 'vcodec': 'h263'},
-    '6': {'ext': 'flv', 'width': 450, 'height': 270, 'acodec': 'mp3', 'abr': 64, 'vcodec': 'h263'},
-    '13': {'ext': '3gp', 'acodec': 'aac', 'vcodec': 'mp4v'},
-    '17': {'ext': '3gp', 'width': 176, 'height': 144, 'acodec': 'aac', 'abr': 24, 'vcodec': 'mp4v'},
-    '18': {'ext': 'mp4', 'width': 640, 'height': 360, 'acodec': 'aac', 'abr': 96, 'vcodec': 'h264'},
-    '22': {'ext': 'mp4', 'width': 1280, 'height': 720, 'acodec': 'aac', 'abr': 192, 'vcodec': 'h264'},
-    '34': {'ext': 'flv', 'width': 640, 'height': 360, 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264'},
-    '35': {'ext': 'flv', 'width': 854, 'height': 480, 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264'},
-    # itag 36 videos are either 320x180 (BaW_jenozKc) or 320x240 (__2ABJjxzNo), abr varies as well
-    '36': {'ext': '3gp', 'width': 320, 'acodec': 'aac', 'vcodec': 'mp4v'},
-    '37': {'ext': 'mp4', 'width': 1920, 'height': 1080, 'acodec': 'aac', 'abr': 192, 'vcodec': 'h264'},
-    '38': {'ext': 'mp4', 'width': 4096, 'height': 3072, 'acodec': 'aac', 'abr': 192, 'vcodec': 'h264'},
-    '43': {'ext': 'webm', 'width': 640, 'height': 360, 'acodec': 'vorbis', 'abr': 128, 'vcodec': 'vp8'},
-    '44': {'ext': 'webm', 'width': 854, 'height': 480, 'acodec': 'vorbis', 'abr': 128, 'vcodec': 'vp8'},
-    '45': {'ext': 'webm', 'width': 1280, 'height': 720, 'acodec': 'vorbis', 'abr': 192, 'vcodec': 'vp8'},
-    '46': {'ext': 'webm', 'width': 1920, 'height': 1080, 'acodec': 'vorbis', 'abr': 192, 'vcodec': 'vp8'},
-    '59': {'ext': 'mp4', 'width': 854, 'height': 480, 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264'},
-    '78': {'ext': 'mp4', 'width': 854, 'height': 480, 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264'},
-
-
-    # 3D videos
-    '82': {'ext': 'mp4', 'height': 360, 'format_note': '3D', 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264', 'preference': -20},
-    '83': {'ext': 'mp4', 'height': 480, 'format_note': '3D', 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264', 'preference': -20},
-    '84': {'ext': 'mp4', 'height': 720, 'format_note': '3D', 'acodec': 'aac', 'abr': 192, 'vcodec': 'h264', 'preference': -20},
-    '85': {'ext': 'mp4', 'height': 1080, 'format_note': '3D', 'acodec': 'aac', 'abr': 192, 'vcodec': 'h264', 'preference': -20},
-    '100': {'ext': 'webm', 'height': 360, 'format_note': '3D', 'acodec': 'vorbis', 'abr': 128, 'vcodec': 'vp8', 'preference': -20},
-    '101': {'ext': 'webm', 'height': 480, 'format_note': '3D', 'acodec': 'vorbis', 'abr': 192, 'vcodec': 'vp8', 'preference': -20},
-    '102': {'ext': 'webm', 'height': 720, 'format_note': '3D', 'acodec': 'vorbis', 'abr': 192, 'vcodec': 'vp8', 'preference': -20},
-
-    # Apple HTTP Live Streaming
-    '91': {'ext': 'mp4', 'height': 144, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 48, 'vcodec': 'h264', 'preference': -10},
-    '92': {'ext': 'mp4', 'height': 240, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 48, 'vcodec': 'h264', 'preference': -10},
-    '93': {'ext': 'mp4', 'height': 360, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264', 'preference': -10},
-    '94': {'ext': 'mp4', 'height': 480, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 128, 'vcodec': 'h264', 'preference': -10},
-    '95': {'ext': 'mp4', 'height': 720, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 256, 'vcodec': 'h264', 'preference': -10},
-    '96': {'ext': 'mp4', 'height': 1080, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 256, 'vcodec': 'h264', 'preference': -10},
-    '132': {'ext': 'mp4', 'height': 240, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 48, 'vcodec': 'h264', 'preference': -10},
-    '151': {'ext': 'mp4', 'height': 72, 'format_note': 'HLS', 'acodec': 'aac', 'abr': 24, 'vcodec': 'h264', 'preference': -10},
-
-    # DASH mp4 video
-    '133': {'ext': 'mp4', 'height': 240, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '134': {'ext': 'mp4', 'height': 360, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '135': {'ext': 'mp4', 'height': 480, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '136': {'ext': 'mp4', 'height': 720, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '137': {'ext': 'mp4', 'height': 1080, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '138': {'ext': 'mp4', 'format_note': 'DASH video', 'vcodec': 'h264'},  # Height can vary (https://github.com/rg3/youtube-dl/issues/4559)
-    '160': {'ext': 'mp4', 'height': 144, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '212': {'ext': 'mp4', 'height': 480, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '264': {'ext': 'mp4', 'height': 1440, 'format_note': 'DASH video', 'vcodec': 'h264'},
-    '298': {'ext': 'mp4', 'height': 720, 'format_note': 'DASH video', 'vcodec': 'h264', 'fps': 60},
-    '299': {'ext': 'mp4', 'height': 1080, 'format_note': 'DASH video', 'vcodec': 'h264', 'fps': 60},
-    '266': {'ext': 'mp4', 'height': 2160, 'format_note': 'DASH video', 'vcodec': 'h264'},
-
-    # Dash mp4 audio
-    '139': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'aac', 'abr': 48, 'container': 'm4a_dash'},
-    '140': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'aac', 'abr': 128, 'container': 'm4a_dash'},
-    '141': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'aac', 'abr': 256, 'container': 'm4a_dash'},
-    '256': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'aac', 'container': 'm4a_dash'},
-    '258': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'aac', 'container': 'm4a_dash'},
-    '325': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'dtse', 'container': 'm4a_dash'},
-    '328': {'ext': 'm4a', 'format_note': 'DASH audio', 'acodec': 'ec-3', 'container': 'm4a_dash'},
-
-    # Dash webm
-    '167': {'ext': 'webm', 'height': 360, 'width': 640, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '168': {'ext': 'webm', 'height': 480, 'width': 854, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '169': {'ext': 'webm', 'height': 720, 'width': 1280, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '170': {'ext': 'webm', 'height': 1080, 'width': 1920, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '218': {'ext': 'webm', 'height': 480, 'width': 854, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '219': {'ext': 'webm', 'height': 480, 'width': 854, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp8'},
-    '278': {'ext': 'webm', 'height': 144, 'format_note': 'DASH video', 'container': 'webm', 'vcodec': 'vp9'},
-    '242': {'ext': 'webm', 'height': 240, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '243': {'ext': 'webm', 'height': 360, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '244': {'ext': 'webm', 'height': 480, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '245': {'ext': 'webm', 'height': 480, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '246': {'ext': 'webm', 'height': 480, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '247': {'ext': 'webm', 'height': 720, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '248': {'ext': 'webm', 'height': 1080, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '271': {'ext': 'webm', 'height': 1440, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    # itag 272 videos are either 3840x2160 (e.g. RtoitU2A-3E) or 7680x4320 (sLprVF6d7Ug)
-    '272': {'ext': 'webm', 'height': 2160, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '302': {'ext': 'webm', 'height': 720, 'format_note': 'DASH video', 'vcodec': 'vp9', 'fps': 60},
-    '303': {'ext': 'webm', 'height': 1080, 'format_note': 'DASH video', 'vcodec': 'vp9', 'fps': 60},
-    '308': {'ext': 'webm', 'height': 1440, 'format_note': 'DASH video', 'vcodec': 'vp9', 'fps': 60},
-    '313': {'ext': 'webm', 'height': 2160, 'format_note': 'DASH video', 'vcodec': 'vp9'},
-    '315': {'ext': 'webm', 'height': 2160, 'format_note': 'DASH video', 'vcodec': 'vp9', 'fps': 60},
-
-    # Dash webm audio
-    '171': {'ext': 'webm', 'acodec': 'vorbis', 'format_note': 'DASH audio', 'abr': 128},
-    '172': {'ext': 'webm', 'acodec': 'vorbis', 'format_note': 'DASH audio', 'abr': 256},
-
-    # Dash webm audio with opus inside
-    '249': {'ext': 'webm', 'format_note': 'DASH audio', 'acodec': 'opus', 'abr': 50},
-    '250': {'ext': 'webm', 'format_note': 'DASH audio', 'acodec': 'opus', 'abr': 70},
-    '251': {'ext': 'webm', 'format_note': 'DASH audio', 'acodec': 'opus', 'abr': 160},
-
-    # RTMP (unnamed)
-    '_rtmp': {'protocol': 'rtmp'},
-}
-
-
-
-
-
-
-with open("yt_watch_template.html", "r") as file:
-    yt_watch_template = Template(file.read())
-    
 
 def get_related_items_html(info):
     result = ""
@@ -156,51 +46,45 @@ def watch_page_related_playlist_info(item):
         'thumbnail': util.get_thumbnail_url(item['video_id']),
     }
 
-    
-def sort_formats(info):
-    sorted_formats = info['formats'].copy()
-    sorted_formats.sort(key=lambda x: util.default_multi_get(_formats, x['format_id'], 'height', default=0))
-    for index, format in enumerate(sorted_formats):
-        if util.default_multi_get(_formats, format['format_id'], 'height', default=0) >= 360:
-            break
-    sorted_formats = sorted_formats[index:] + sorted_formats[0:index]
-    sorted_formats = [format for format in info['formats'] if format['acodec'] != 'none' and format['vcodec'] != 'none']
-    return sorted_formats
-
-source_tag_template = Template('''
-<source src="$src" type="$type">''')
-def formats_html(formats):
-    result = ''
-    for format in formats:
-        result += source_tag_template.substitute(
-            src=format['url'],
-            type='audio/' + format['ext'] if format['vcodec'] == "none" else 'video/' + format['ext'],
-        )
-    return result
+def get_video_sources(info):
+    video_sources = []
+    for format in info['formats']:
+        if format['acodec'] != 'none' and format['vcodec'] != 'none':
+            video_sources.append({
+                'src': format['url'],
+                'type': 'video/' + format['ext'],
+            })
 
+    return video_sources
 
-subtitles_tag_template = Template('''
-<track label="$label" src="$src" kind="subtitles" srclang="$srclang" $default>''')
-def subtitles_html(info):
-    result = ''
+def get_subtitle_sources(info):
+    sources = []
     default_found = False
-    default = ''
+    default = None
     for language, formats in info['subtitles'].items():
         for format in formats:
             if format['ext'] == 'vtt':
-                append = subtitles_tag_template.substitute(
-                    src = html.escape('/' + format['url']),
-                    label = html.escape(language),
-                    srclang = html.escape(language),
-                    default = 'default' if language == settings.subtitles_language and settings.subtitles_mode > 0 else '',
-                )
+                source = {
+                    'url': '/' + format['url'],
+                    'label': language,
+                    'srclang': language,
+
+                    # set as on by default if this is the preferred language and a default-on subtitles mode is in settings
+                    'on': language == settings.subtitles_language and settings.subtitles_mode > 0,
+                }
+
                 if language == settings.subtitles_language:
                     default_found = True
-                    default = append
+                    default = source
                 else:
-                    result += append
+                    result.append(source)
                 break
-    result += default
+
+    # Put it at the end to avoid browser bug when there are too many languages
+    # (in firefox, it is impossible to select a language near the top of the list because it is cut off)
+    if default_found:
+        sources.append(default)
+
     try:
         formats = info['automatic_captions'][settings.subtitles_language]
     except KeyError:
@@ -208,19 +92,60 @@ def subtitles_html(info):
     else:
         for format in formats:
             if format['ext'] == 'vtt':
-                result += subtitles_tag_template.substitute(
-                    src = html.escape('/' + format['url']),
-                    label = settings.subtitles_language + ' - Automatic',
-                    srclang = settings.subtitles_language,
-                    default = 'default' if settings.subtitles_mode == 2 and not default_found else '',
-                )
-    return result
+                sources.append({
+                    'url': '/' + format['url'],
+                    'label': settings.subtitles_language + ' - Automatic',
+                    'srclang': settings.subtitles_language,
+
+                    # set as on by default if this is the preferred language and a default-on subtitles mode is in settings
+                    'on': settings.subtitles_mode == 2 and not default_found,
+
+                })
+
+    return sources
+
+
+def get_music_list_html(music_list):
+    if len(music_list) == 0:
+        music_list_html = ''
+    else:
+        # get the set of attributes which are used by atleast 1 track
+        # so there isn't an empty, extraneous album column which no tracks use, for example
+        used_attributes = set()
+        for track in music_list:
+            used_attributes = used_attributes | track.keys()
+
+        # now put them in the right order
+        ordered_attributes = []
+        for attribute in ('Artist', 'Title', 'Album'):
+            if attribute.lower() in used_attributes:
+                ordered_attributes.append(attribute)
+
+        music_list_html = '''<hr>
+<table>
+<caption>Music</caption>
+<tr>
+'''
+        # table headings
+        for attribute in ordered_attributes:
+            music_list_html += "<th>" + attribute + "</th>\n"
+        music_list_html += '''</tr>\n'''
+
+        for track in music_list:
+            music_list_html += '''<tr>\n'''
+            for attribute in ordered_attributes:
+                try:
+                    value = track[attribute.lower()]
+                except KeyError:
+                    music_list_html += '''<td></td>'''
+                else:
+                    music_list_html += '''<td>''' + html.escape(value) + '''</td>'''
+            music_list_html += '''</tr>\n'''
+        music_list_html += '''</table>\n'''
+    return music_list_html
 
 
-more_comments_template = Template('''<a class="page-button more-comments" href="$url">More comments</a>''')
 
-download_link_template = Template('''
-<a href="$url"> <span>$ext</span> <span>$resolution</span> <span>$note</span></a>''')
 
 def extract_info(downloader, *args, **kwargs):
     try:
@@ -228,136 +153,87 @@ def extract_info(downloader, *args, **kwargs):
     except YoutubeError as e:
         return str(e)
 
-music_list_table_row = Template('''<tr>
-    <td>$attribute</td>
-    <td>$value</td>
-''')
-def get_watch_page(env, start_response):
-        video_id = env['parameters']['v'][0]
-        if len(video_id) < 11:
-            start_response('404 Not Found', [('Content-type', 'text/plain'),])
-            return b'Incomplete video id (too short): ' + video_id.encode('ascii')
-
-        start_response('200 OK', [('Content-type','text/html'),])
-
-        lc = util.default_multi_get(env['parameters'], 'lc', 0, default='')
-        if settings.route_tor:
-            proxy = 'socks5://127.0.0.1:9150/'
-        else:
-            proxy = ''
-        downloader = YoutubeDL(params={'youtube_include_dash_manifest':False, 'proxy':proxy})
-        tasks = (
-            gevent.spawn(comments.video_comments, video_id, int(settings.default_comment_sorting), lc=lc ),
-            gevent.spawn(extract_info, downloader, "https://www.youtube.com/watch?v=" + video_id, download=False)
-        )
-        gevent.joinall(tasks)
-        comments_html, info = tasks[0].value, tasks[1].value
-
-
-        #comments_html = comments.comments_html(video_id(url))
-        #info = YoutubeDL().extract_info(url, download=False)
-        
-        #chosen_format = choose_format(info)
-
-        if isinstance(info, str): # youtube error
-            return html_common.yt_basic_template.substitute(
-                page_title = "Error",
-                style = "",
-                header = html_common.get_header(),
-                page = html.escape(info),
-            ).encode('utf-8')
-            
-        sorted_formats = sort_formats(info)
-        
-        video_info = {
-            "duration": util.seconds_to_timestamp(info["duration"]),
-            "id":       info['id'],
-            "title":    info['title'],
-            "author":   info['uploader'],
-        }
-
-        upload_year = info["upload_date"][0:4]
-        upload_month = info["upload_date"][4:6]
-        upload_day = info["upload_date"][6:8]
-        upload_date = upload_month + "/" + upload_day + "/" + upload_year
-        
-        if settings.enable_related_videos:
-            related_videos_html = get_related_items_html(info)
-        else:
-            related_videos_html = ''
 
-        music_list = info['music_list']
-        if len(music_list) == 0:
-            music_list_html = ''
-        else:
-            # get the set of attributes which are used by atleast 1 track
-            # so there isn't an empty, extraneous album column which no tracks use, for example
-            used_attributes = set()
-            for track in music_list:
-                used_attributes = used_attributes | track.keys()
-
-            # now put them in the right order
-            ordered_attributes = []
-            for attribute in ('Artist', 'Title', 'Album'):
-                if attribute.lower() in used_attributes:
-                    ordered_attributes.append(attribute)
-
-            music_list_html = '''<hr>
-<table>
-    <caption>Music</caption>
-    <tr>
-'''
-            # table headings
-            for attribute in ordered_attributes:
-                music_list_html += "<th>" + attribute + "</th>\n"
-            music_list_html += '''</tr>\n'''
 
-            for track in music_list:
-                music_list_html += '''<tr>\n'''
-                for attribute in ordered_attributes:
-                    try:
-                        value = track[attribute.lower()]
-                    except KeyError:
-                        music_list_html += '''<td></td>'''
-                    else:
-                        music_list_html += '''<td>''' + html.escape(value) + '''</td>'''
-                music_list_html += '''</tr>\n'''
-            music_list_html += '''</table>\n'''
-        if settings.gather_googlevideo_domains:
-            with open(os.path.join(settings.data_dir, 'googlevideo-domains.txt'), 'a+', encoding='utf-8') as f:
-                url = info['formats'][0]['url']
-                subdomain = url[0:url.find(".googlevideo.com")]
-                f.write(subdomain + "\n")
-
-        download_options = ''
-        for format in info['formats']:
-            download_options += download_link_template.substitute(
-                url        = html.escape(format['url']),
-                ext         = html.escape(format['ext']),
-                resolution  = html.escape(downloader.format_resolution(format)),
-                note        = html.escape(downloader._format_note(format)),
-            )
-
-
-        page = yt_watch_template.substitute(
-            video_title             = html.escape(info["title"]),
-            page_title              = html.escape(info["title"]),
-            header                  = html_common.get_header(),
-            uploader                = html.escape(info["uploader"]),
-            uploader_channel_url    = '/' + info["uploader_url"],
-            upload_date             = upload_date,
-            views           = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("view_count", None)),
-            likes           = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("like_count", None)),
-            dislikes        = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("dislike_count", None)),
-            download_options        = download_options,
-            video_info              = html.escape(json.dumps(video_info)),
-            description             = html.escape(info["description"]),
-            video_sources           = formats_html(sorted_formats) + subtitles_html(info),
-            related                 = related_videos_html,
-
-            comments                = comments_html,
-
-            music_list              = music_list_html,
-            is_unlisted             = '<span class="is-unlisted">Unlisted</span>' if info['unlisted'] else '',
-        )
-        return page.encode('utf-8')
+
+@yt_app.route('/watch')
+def get_watch_page():
+    video_id = request.args['v']
+    if len(video_id) < 11:
+        abort(404)
+        abort(Response('Incomplete video id (too short): ' + video_id))
+
+    lc = request.args.get('lc', '')
+    if settings.route_tor:
+        proxy = 'socks5://127.0.0.1:9150/'
+    else:
+        proxy = ''
+    yt_dl_downloader = YoutubeDL(params={'youtube_include_dash_manifest':False, 'proxy':proxy})
+    tasks = (
+        gevent.spawn(comments.video_comments, video_id, int(settings.default_comment_sorting), lc=lc ),
+        gevent.spawn(extract_info, yt_dl_downloader, "https://www.youtube.com/watch?v=" + video_id, download=False)
+    )
+    gevent.joinall(tasks)
+    comments_html, info = tasks[0].value, tasks[1].value
+
+    if isinstance(info, str): # youtube error
+        return flask.render_template('error.html', header = html_common.get_header, error_mesage = info)
+
+    video_info = {
+        "duration": util.seconds_to_timestamp(info["duration"]),
+        "id":       info['id'],
+        "title":    info['title'],
+        "author":   info['uploader'],
+    }
+
+    upload_year = info["upload_date"][0:4]
+    upload_month = info["upload_date"][4:6]
+    upload_day = info["upload_date"][6:8]
+    upload_date = upload_month + "/" + upload_day + "/" + upload_year
+    
+    if settings.enable_related_videos:
+        related_videos_html = get_related_items_html(info)
+    else:
+        related_videos_html = ''
+
+
+    if settings.gather_googlevideo_domains:
+        with open(os.path.join(settings.data_dir, 'googlevideo-domains.txt'), 'a+', encoding='utf-8') as f:
+            url = info['formats'][0]['url']
+            subdomain = url[0:url.find(".googlevideo.com")]
+            f.write(subdomain + "\n")
+
+
+    download_formats = []
+
+    for format in info['formats']:
+        download_formats.append({
+            'url': format['url'],
+            'ext': format['ext'],
+            'resolution': yt_dl_downloader.format_resolution(format),
+            'note': yt_dl_downloader._format_note(format),
+        })
+
+
+    return flask.render_template('watch.html',
+        header                  = html_common.get_header(),
+        uploader_channel_url    = '/' + info['uploader_url'],
+        upload_date             = upload_date,
+        views           = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("view_count", None)),
+        likes           = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("like_count", None)),
+        dislikes        = (lambda x: '{:,}'.format(x) if x is not None else "")(info.get("dislike_count", None)),
+        download_formats        = download_formats,
+        video_info              = json.dumps(video_info),
+        video_sources           = get_video_sources(info),
+        subtitle_sources        = get_subtitle_sources(info),
+
+        # TODO: refactor these
+        related                 = related_videos_html,
+        comments                = comments_html,
+        music_list              = get_music_list_html(info['music_list']),
+
+        title       = info['title'],
+        uploader    = info['uploader'],
+        description = info['description'],
+        unlisted    = info['unlisted'],
+    )
diff --git a/youtube/youtube.py b/youtube/youtube.py
deleted file mode 100644
index a6a216e..0000000
--- a/youtube/youtube.py
+++ /dev/null
@@ -1,105 +0,0 @@
-import mimetypes
-import urllib.parse
-import os
-from youtube import local_playlist, watch, search, playlist, channel, comments, post_comment, accounts, util
-import settings
-YOUTUBE_FILES = (
-    "/shared.css",
-    '/comments.css',
-    '/favicon.ico',
-)
-get_handlers = {
-    'search':           search.get_search_page,
-    '':                 search.get_search_page,
-    'watch':            watch.get_watch_page,
-    'playlist':         playlist.get_playlist_page,
-
-    'channel':          channel.get_channel_page,
-    'user':             channel.get_channel_page_general_url,
-    'c':                channel.get_channel_page_general_url,
-
-    'playlists':        local_playlist.get_playlist_page,
-
-    'comments':         comments.get_comments_page,
-    'post_comment':     post_comment.get_post_comment_page,
-    'delete_comment':   post_comment.get_delete_comment_page,
-    'login':            accounts.get_account_login_page,
-}
-post_handlers = {
-    'edit_playlist':    local_playlist.edit_playlist,
-    'playlists':        local_playlist.path_edit_playlist,
-
-    'login':            accounts.add_account,
-    'comments':         post_comment.post_comment,
-    'post_comment':     post_comment.post_comment,
-    'delete_comment':   post_comment.delete_comment,
-}
-
-def youtube(env, start_response):
-    path, method, query_string = env['PATH_INFO'], env['REQUEST_METHOD'], env['QUERY_STRING']
-    env['qs_parameters'] = urllib.parse.parse_qs(query_string)
-    env['parameters'] = dict(env['qs_parameters'])
-
-    path_parts = path.rstrip('/').lstrip('/').split('/')
-    env['path_parts'] = path_parts
-
-    if method == "GET":
-        try:
-            handler = get_handlers[path_parts[0]]
-        except KeyError:
-            pass
-        else:
-            return handler(env, start_response)
-
-        if path in YOUTUBE_FILES:
-            with open("youtube" + path, 'rb') as f:
-                mime_type = mimetypes.guess_type(path)[0] or 'application/octet-stream'
-                start_response('200 OK',  (('Content-type',mime_type),) )
-                return f.read()
-
-        elif path.startswith("/data/playlist_thumbnails/"):
-            with open(os.path.join(settings.data_dir, os.path.normpath(path[6:])), 'rb') as f:
-                start_response('200 OK',  (('Content-type', "image/jpeg"),) )
-                return f.read()
-
-        elif path.startswith("/api/"):
-            start_response('200 OK',  [('Content-type', 'text/vtt'),] )
-            result = util.fetch_url('https://www.youtube.com' + path + ('?' + query_string if query_string else ''))
-            result = result.replace(b"align:start position:0%", b"")
-            return result
-
-        elif path == "/opensearch.xml":
-            with open("youtube" + path, 'rb') as f:
-                mime_type = mimetypes.guess_type(path)[0] or 'application/octet-stream'
-                start_response('200 OK',  (('Content-type',mime_type),) )
-                return f.read().replace(b'$port_number', str(settings.port_number).encode())
-
-        elif path == "/comment_delete_success":
-            start_response('200 OK', [('Content-type', 'text/plain'),] )
-            return b'Successfully deleted comment'
-
-        elif path == "/comment_delete_fail":
-            start_response('200 OK',  [('Content-type', 'text/plain'),] )
-            return b'Failed to deleted comment'
-
-        else:
-            return channel.get_channel_page_general_url(env, start_response)
-
-    elif method == "POST":
-        post_parameters = urllib.parse.parse_qs(env['wsgi.input'].read().decode())
-        env['post_parameters'] = post_parameters
-        env['parameters'].update(post_parameters)
-
-        try:
-            handler = post_handlers[path_parts[0]]
-        except KeyError:
-            pass
-        else:
-            return handler(env, start_response)
-
-        start_response('404 Not Found', [('Content-type', 'text/plain'),])
-        return b'404 Not Found'
-
-    else:
-        start_response('501 Not Implemented', [('Content-type', 'text/plain'),])
-        return b'501 Not Implemented'