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#!/usr/bin/env python
# -*- mode:python; tab-width: 2; coding: utf-8 -*-
"""Partially backported python ABC classes"""
from __future__ import absolute_import
try:
from collections import MutableSet
except ImportError:
# Running in Python <= 2.5
from ._abc import MutableSet
KEY, PREV, NEXT = range(3)
class OrderedSet(MutableSet):
def __init__(self, iterable=None):
self.end = end = []
end += [None, end, end] # sentinel node for doubly linked list
self.map = {} # key --> [key, prev, next]
if iterable is not None:
self |= iterable
def __len__(self):
return len(self.map)
def __contains__(self, key):
return key in self.map
def __getitem__(self, key):
return list(self)[key]
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 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):
if all([KEY, PREV, NEXT]):
self.clear() # remove circular references
oset = OrderedSet
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