Mercurial > cpython-lru_cache-weakref

diff Objects/setobject.c @ 32319:b9de6b665273 legacy-trunk

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Fixups to the hash function for frozensets. * Non-zero initial value so that hash(frozenset()) != hash(0). * Final permutation to differentiate nested sets. * Add logic to make sure that -1 is not a possible hash value.
author Raymond Hettinger <python@rcn.com>
date Thu, 10 Jun 2004 21:38:41 +0000
parents 679e5c8effae
children 87302ac07255
line wrap: on
line diff
--- a/Objects/setobject.c	Thu Jun 10 18:42:15 2004 +0000
+++ b/Objects/setobject.c	Thu Jun 10 21:38:41 2004 +0000
@@ -663,7 +663,7 @@
 	PySetObject *so = (PySetObject *)self;
 	PyObject *key, *value;
 	int pos = 0;
-	long hash = 0;
+	long hash = 1905176217L;
 
 	if (so->hash != -1)
 		return so->hash;
@@ -676,6 +676,9 @@
 		   collapse to only a handful of distinct hash values. */
 		hash ^= PyObject_Hash(key) * 3644798167u;
 	}
+	hash *= 69069L;
+	if (hash == -1)
+		hash = 590923713L;
 	so->hash = hash;
 	return hash;
 }