''' OrderedSet
Copied from http://code.activestate.com/recipes/576694/
Created by Raymond Hettinger
Licensed under the MIT License
Modified by David L. Armstrong to avoid use of 'next' keyword
and add indexing support
'''
import collections
KEY, PREV, NEXT = range(3)
class OrderedSet(collections.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 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, prevItem, nextItem = self.map.pop(key)
prevItem[NEXT] = nextItem
nextItem[PREV] = prevItem
# indexing support
def __getitem__(self, key):
if not isinstance(key, int):
raise KeyError(key)
if key >= len(self) or key < (len(self) * -1):
raise KeyError(key)
counter = 0
if key >= 0:
item = self.end
while counter <= key:
item = item[NEXT]
counter += 1
return item[KEY]
else:
item = self.end
while counter > key: # > because 0 is the start, not 1
item = item[PREV]
counter -= 1
return item[KEY]
# catchall
raise KeyError(key)
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() # remove circular references