add code for analysis of data

1 files changed, 1010 insertions, 0 deletions

diff --git a/venv/lib/python3.8/site-packages/werkzeug/datastructures/structures.py b/venv/lib/python3.8/site-packages/werkzeug/datastructures/structures.py
new file mode 100644
index 0000000..4279ceb
--- /dev/null
+++ b/venv/lib/python3.8/site-packages/werkzeug/datastructures/structures.py
@@ -0,0 +1,1010 @@
+from __future__ import annotations
+
+from collections.abc import MutableSet
+from copy import deepcopy
+
+from .. import exceptions
+from .._internal import _missing
+from .mixins import ImmutableDictMixin
+from .mixins import ImmutableListMixin
+from .mixins import ImmutableMultiDictMixin
+from .mixins import UpdateDictMixin
+
+
+def is_immutable(self):
+    raise TypeError(f"{type(self).__name__!r} objects are immutable")
+
+
+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):
+        yield from mapping.items(multi=True)
+    elif isinstance(mapping, dict):
+        for key, value in mapping.items():
+            if isinstance(value, (tuple, list)):
+                for v in value:
+                    yield key, v
+            else:
+                yield key, value
+    else:
+        yield from mapping
+
+
+class ImmutableList(ImmutableListMixin, list):
+    """An immutable :class:`list`.
+
+    .. versionadded:: 0.5
+
+    :private:
+    """
+
+    def __repr__(self):
+        return f"{type(self).__name__}({list.__repr__(self)})"
+
+
+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` or a
+                     :exc:`TypeError` is raised by this callable the default
+                     value is returned.
+
+        .. versionchanged:: 3.0.2
+           Returns the default value on :exc:`TypeError`, too.
+        """
+        try:
+            rv = self[key]
+        except KeyError:
+            return default
+        if type is not None:
+            try:
+                rv = type(rv)
+            except (ValueError, TypeError):
+                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 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, vs[:]) for k, vs in mapping.lists()))
+        elif isinstance(mapping, dict):
+            tmp = {}
+            for key, value in mapping.items():
+                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 __iter__(self):
+        # Work around https://bugs.python.org/issue43246.
+        # (`return super().__iter__()` also works here, which makes this look
+        # even more like it should be a no-op, yet it isn't.)
+        return dict.__iter__(self)
+
+    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 like `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 dict.items(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 dict.items(self):
+            yield key, list(values)
+
+    def values(self):
+        """Returns an iterator of the first value on every key's value list."""
+        for values in dict.values(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 dict.values(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(self.items())
+        return dict(self.lists())
+
+    def update(self, mapping):
+        """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(mapping):
+            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) from None
+
+    def popitem(self):
+        """Pop an item from the dict."""
+        try:
+            item = dict.popitem(self)
+
+            if len(item[1]) == 0:
+                raise exceptions.BadRequestKeyError(item[0])
+
+            return (item[0], item[1][0])
+        except KeyError as e:
+            raise exceptions.BadRequestKeyError(e.args[0]) from None
+
+    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]) from None
+
+    def __copy__(self):
+        return self.copy()
+
+    def __deepcopy__(self, memo):
+        return self.deepcopy(memo=memo)
+
+    def __repr__(self):
+        return f"{type(self).__name__}({list(self.items(multi=True))!r})"
+
+
+class _omd_bucket:
+    """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
+
+
+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 = iter(self.items(multi=True))
+            iter2 = iter(other.items(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 self.lists():
+            if other.getlist(key) != values:
+                return False
+        return True
+
+    __hash__ = None
+
+    def __reduce_ex__(self, protocol):
+        return type(self), (list(self.items(multi=True)),)
+
+    def __getstate__(self):
+        return list(self.items(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 self.items())
+
+    def __iter__(self):
+        return iter(self.keys())
+
+    def values(self):
+        return (value for key, value in self.items())
+
+    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 self.lists():
+            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) from None
+
+        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]) from None
+
+        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]) from None
+
+        for bucket in buckets:
+            bucket.unlink(self)
+
+        return key, [x.value for x in buckets]
+
+
+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 = list(dicts) or []
+
+    @classmethod
+    def fromkeys(cls, keys, value=None):
+        raise TypeError(f"cannot create {cls.__name__!r} instances by fromkeys")
+
+    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.
+        """
+        rv = set()
+        rv.update(*self.dicts)
+        return rv
+
+    def keys(self):
+        return self._keys_impl()
+
+    def __iter__(self):
+        return iter(self.keys())
+
+    def items(self, multi=False):
+        found = set()
+        for d in self.dicts:
+            for key, value in d.items(multi):
+                if multi:
+                    yield key, value
+                elif key not in found:
+                    found.add(key)
+                    yield key, value
+
+    def values(self):
+        for _key, value in self.items():
+            yield value
+
+    def lists(self):
+        rv = {}
+        for d in self.dicts:
+            for key, values in d.lists():
+                rv.setdefault(key, []).extend(values)
+        return list(rv.items())
+
+    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`
+        """
+        if flat:
+            return dict(self.items())
+
+        return dict(self.lists())
+
+    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
+
+    def __repr__(self):
+        return f"{type(self).__name__}({self.dicts!r})"
+
+
+class ImmutableDict(ImmutableDictMixin, dict):
+    """An immutable :class:`dict`.
+
+    .. versionadded:: 0.5
+    """
+
+    def __repr__(self):
+        return f"{type(self).__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(self.items(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
+
+
+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 f"<{type(self).__name__} {dict.__repr__(self)}>"
+
+
+class HeaderSet(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 = {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:
+            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(http.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 __bool__(self):
+        return bool(self._set)
+
+    def __str__(self):
+        return self.to_header()
+
+    def __repr__(self):
+        return f"{type(self).__name__}({self._headers!r})"
+
+
+# circular dependencies
+from .. import http