import collections
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[1]
curr[2] = end[1] = self.map[key] = [key, curr, end]
def discard(self, key):
if key in self.map:
key, prev, next = self.map.pop(key)
prev[2] = next
next[1] = prev
def __iter__(self):
end = self.end
curr = end[2]
while curr is not end:
yield curr[0]
curr = curr[2]
def __reversed__(self):
end = self.end
curr = end[1]
while curr is not end:
yield curr[0]
curr = curr[1]
def pop(self, last=True):
if not self:
raise KeyError('set is empty')
key = self.end[1][0] if last else self.end[2][0]
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)
if __name__ == '__main__':
s = OrderedSet('abracadaba')
t = OrderedSet('simsalabim')
print(s | t)
print(s & t)
print(s - t)
Diff to Previous Revision
--- revision 8 2012-12-18 20:38:26
+++ revision 9 2012-12-19 07:12:32
@@ -1,6 +1,4 @@
import collections
-
-KEY, PREV, NEXT = range(3)
class OrderedSet(collections.MutableSet):
@@ -20,33 +18,33 @@
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]
+ curr = end[1]
+ curr[2] = end[1] = 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
+ prev[2] = next
+ next[1] = prev
def __iter__(self):
end = self.end
- curr = end[NEXT]
+ curr = end[2]
while curr is not end:
- yield curr[KEY]
- curr = curr[NEXT]
+ yield curr[0]
+ curr = curr[2]
def __reversed__(self):
end = self.end
- curr = end[PREV]
+ curr = end[1]
while curr is not end:
- yield curr[KEY]
- curr = curr[PREV]
+ yield curr[0]
+ curr = curr[1]
def pop(self, last=True):
if not self:
raise KeyError('set is empty')
- key = next(reversed(self)) if last else next(iter(self))
+ key = self.end[1][0] if last else self.end[2][0]
self.discard(key)
return key
@@ -62,5 +60,8 @@
if __name__ == '__main__':
- print(OrderedSet('abracadaba'))
- print(OrderedSet('simsalabim'))
+ s = OrderedSet('abracadaba')
+ t = OrderedSet('simsalabim')
+ print(s | t)
+ print(s & t)
+ print(s - t)
