import collections
import operator
import functools


class frozendict(collections.Mapping):

    def __init__(self, *args, **kwargs):
        self.__dict = dict(*args, **kwargs)
        self.__hash = None

    def __getitem__(self, key):
        return self.__dict[key]

    def copy(self, **add_or_replace):
        return frozendict(self, **add_or_replace)

    def __iter__(self):
        return iter(self.__dict)

    def __len__(self):
        return len(self.__dict)

    def __repr__(self):
        return '<frozendict %s>' % repr(self.__dict)

    def __hash__(self):
        if self.__hash is None:
            hashes = map(hash, self.items())
            self.__hash = functools.reduce(operator.xor, hashes, 0)

        return self.__hash


class FrozenOrderedDict(collections.Mapping):
    """
    It is an immutable wrapper around ordered dictionaries that implements the complete :py:class:`collections.Mapping`
    interface. It can be used as a drop-in replacement for dictionaries where immutability and ordering are desired.
    """

    def __init__(self, *args, **kwargs):
        self.__dict = collections.OrderedDict(*args, **kwargs)
        self.__hash = None

    def __getitem__(self, key):
        return self.__dict[key]

    def copy(self, **add_or_replace):
        return FrozenOrderedDict(self, **add_or_replace)

    def __iter__(self):
        return iter(self.__dict)

    def __len__(self):
        return len(self.__dict)

    def __repr__(self):
        return '<FrozenOrderedDict %s>' % repr(self.__dict)

    def __hash__(self):
        if self.__hash is None:
            hashes = map(hash, self.items())
            self.__hash = functools.reduce(operator.xor, hashes, 0)

        return self.__hash