Author: Lukas Diekmann <[email protected]>
Branch: set-strategies
Changeset: r49263:001538c05f0e
Date: 2011-11-03 17:19 +0100
http://bitbucket.org/pypy/pypy/changeset/001538c05f0e/
Log: in intersection_multiple start with the smallest to avoid
unnecessary comparisons
diff --git a/pypy/objspace/std/setobject.py b/pypy/objspace/std/setobject.py
--- a/pypy/objspace/std/setobject.py
+++ b/pypy/objspace/std/setobject.py
@@ -626,7 +626,29 @@
def intersect_multiple(self, w_set, others_w):
#XXX find smarter implementations
result = w_set.copy_real()
+
+ # find smallest set in others_w to reduce comparisons
+ # XXX maybe we can do this smarter
+ if len(others_w) > 1:
+ startset, startlength = None, 0
+ for w_other in others_w:
+ try:
+ length = self.space.len(w_other)
+ except OperationError, e:
+ if not e.match(self.space, self.space.w_TypeError):
+ raise
+ continue
+
+ if startset is None or
self.space.is_true(self.space.lt(length, startlength)):
+ startset = w_other
+ startlength = length
+
+ others_w[others_w.index(startset)] = others_w[0]
+ others_w[0] = startset
+
for w_other in others_w:
+ if result.length() == 0:
+ break
if isinstance(w_other, W_BaseSetObject):
# optimization only
result.intersect_update(w_other)
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