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Code Issues 32 Releases Wiki Activity

queryset-refactor: Optimised len(qs) and iter(qs) a bit.

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git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7246 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-03-15 09:12:44 +00:00
parent d08ec81228
commit 7534ef1f7e
1 changed files with 19 additions and 3 deletions
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22
django/db/models/query.py
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@ -28,16 +28,32 @@ class _QuerySet(object):
######################## ########################
def __repr__(self): def __repr__(self):
return repr(list(iter(self))) return repr(list(self))
def __len__(self): def __len__(self):
return len(list(iter(self))) # Since __len__ is called quite frequently (as part of list(qs), which
# means as part of qs.get(), for example), we make some effort here to
# be as efficient as possible whilst not messing up any existing
# iterators against the queryset.
if self._result_cache is None:
if self._iter:
self._result_cache = list(self._iter())
else:
self._result_cache = list(self.iterator())
elif self._iter:
self.result_cache.extend(list(self._iter))
return len(self._result_cache)
def __iter__(self): def __iter__(self):
pos = 0
if self._result_cache is None: if self._result_cache is None:
self._iter = self.iterator() self._iter = self.iterator()
self._result_cache = [] self._result_cache = []
if self._iter:
return self._result_iter()
return iter(self._result_cache)
def _result_iter(self):
pos = 0
while 1: while 1:
upper = len(self._result_cache) upper = len(self._result_cache)
while pos < upper: while pos < upper: