# Copyright 2009 Raymond Hettinger
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# Note: Kay Hayen did some changes for Nuitka keeping this license. These
# changes are not improvements, use the original source instead, not this
# file.

""" This module is only an abstraction of OrderedSet as present in 2.7 and 3.1
but not in 2.6.

It was originally downloaded from http://code.activestate.com/recipes/576694/
"""

# pylint: disable=W0622,W0221

import collections

KEY, PREV, NEXT = range(3)

class OrderedSet(collections.MutableSet):

    def __init__(self, iterable=None):
        self.end = end = []
        end += [None, end, end]
        self.map = {}
        if iterable is not None:
            self |= iterable

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

    def __contains__(self, key):
        return key in self.map

    def add(self, key):
        if key not in self.map:
            end = self.end
            curr = end[PREV]
            curr[NEXT] = end[PREV] = self.map[key] = [key, curr, end]

    def update(self, values):
        for value in values:
            self.add( value )

    def discard(self, key):
        if key in self.map:
            key, prev, next = self.map.pop(key)
            prev[NEXT] = next
            next[PREV] = prev

    def __iter__(self):
        end = self.end
        curr = end[NEXT]
        while curr is not end:
            yield curr[KEY]
            curr = curr[NEXT]

    def __reversed__(self):
        end = self.end
        curr = end[PREV]
        while curr is not end:
            yield curr[KEY]
            curr = curr[PREV]

    def pop(self, last=True):
        if not self:
            raise KeyError('set is empty')
        key = next(reversed(self)) if last else next(iter(self))
        self.discard(key)
        return key

    def __repr__(self):
        if not self:
            return '%s()' % (self.__class__.__name__,)
        return '%s(%r)' % (self.__class__.__name__, list(self))

    def __eq__(self, other):
        if isinstance(other, OrderedSet):
            return len(self) == len(other) and list(self) == list(other)
        return set(self) == set(other)

    def __del__(self):
        self.clear()
