Merge flask framework and other stuff from master

1 files changed, 1721 insertions, 0 deletions

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)