Convert watch page to flask framework

1 files changed, 2852 insertions, 0 deletions

diff --git a/python/werkzeug/datastructures.py b/python/werkzeug/datastructures.py
new file mode 100644
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+++ 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