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| author | Raymond Hettinger <python@rcn.com> | 2004-06-10 21:38:41 (GMT) |
|---|---|---|
| committer | Raymond Hettinger <python@rcn.com> | 2004-06-10 21:38:41 (GMT) |
| commit | 27e403ebe914294d307348d2b83c39f96059e133 (patch) | |
| tree | 418e9e758aa28a8458564a140063f70d6c2acec1 /Objects/setobject.c | |
| parent | 57c2d930f688ca50248241919bd815c85bf39939 (diff) | |
| download | cpython-27e403ebe914294d307348d2b83c39f96059e133.zip cpython-27e403ebe914294d307348d2b83c39f96059e133.tar.gz cpython-27e403ebe914294d307348d2b83c39f96059e133.tar.bz2 | |
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.
Diffstat (limited to 'Objects/setobject.c')
| -rw-r--r-- | Objects/setobject.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/Objects/setobject.c b/Objects/setobject.c index fbff077..8de0419 100644 --- a/Objects/setobject.c +++ b/Objects/setobject.c @@ -663,7 +663,7 @@ frozenset_hash(PyObject *self) 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 @@ frozenset_hash(PyObject *self) 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; } |