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Make OrderedDict.popitem() a bit smarter and faster

This commit is contained in:
Raymond Hettinger 2010-09-02 18:44:16 +00:00
parent 19e5a6fb4a
commit 331722d411
1 changed files with 23 additions and 11 deletions
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34
Lib/collections.py
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@ -108,6 +108,29 @@ class OrderedDict(dict, MutableMapping):
pass pass
dict.clear(self) dict.clear(self)
def popitem(self, last=True, PREV=0, NEXT=1, KEY=2, dict_pop=dict.pop):
'''od.popitem() -> (k, v), return and remove a (key, value) pair.
Pairs are returned in LIFO order if last is true or FIFO order if false.
'''
if not self:
raise KeyError('dictionary is empty')
root = self.__root
if last: # link_prev <--> link <--> root
link = root[PREV]
link_prev = link[PREV]
link_prev[NEXT] = root
root[PREV] = link_prev
else: # root <--> link <--> link_next
link = root[NEXT]
link_next = link[NEXT]
root[NEXT] = link_next
link_next[PREV] = root
key = link[KEY]
del self.__map[key]
value = dict_pop(self, key)
return key, value
setdefault = MutableMapping.setdefault setdefault = MutableMapping.setdefault
update = MutableMapping.update update = MutableMapping.update
pop = MutableMapping.pop pop = MutableMapping.pop
@ -116,17 +139,6 @@ class OrderedDict(dict, MutableMapping):
items = MutableMapping.items items = MutableMapping.items
__ne__ = MutableMapping.__ne__ __ne__ = MutableMapping.__ne__
def popitem(self, last=True):
'''od.popitem() -> (k, v), return and remove a (key, value) pair.
Pairs are returned in LIFO order if last is true or FIFO order if false.
'''
if not self:
raise KeyError('dictionary is empty')
key = next(reversed(self) if last else iter(self))
value = self.pop(key)
return key, value
def __repr__(self): def __repr__(self):
'od.__repr__() <==> repr(od)' 'od.__repr__() <==> repr(od)'
if not self: if not self: