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This patch addresses two main issues: (1) There exist some non-fatal

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errors in some of the hash algorithms. For exmaple, in float_hash and
complex_hash a certain part of the value is not included in the hash
calculation. See Tim's, Guido's, and my discussion of this on
python-dev in May under the title "fix float_hash and complex_hash for
64-bit *nix"

(2) The hash algorithms that use pointers (e.g. func_hash, code_hash)
are universally not correct on Win64 (they assume that sizeof(long) ==
sizeof(void*))

As well, this patch significantly cleans up the hash code. It adds the
two function _Py_HashDouble and _PyHash_VoidPtr that the various
hashing routine are changed to use.

These help maintain the hash function invariant: (a==b) =>
(hash(a)==hash(b))) I have added Lib/test/test_hash.py and
Lib/test/output/test_hash to test this for some cases.
This commit is contained in:
Fred Drake 2000-06-29 19:17:04 +00:00
parent b46696c0ed
commit 13634cf7a4
10 changed files with 126 additions and 49 deletions
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26
Lib/test/test_hash.py Normal file
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# test the invariant that
# iff a==b then hash(a)==hash(b)
#
import test_support
def same_hash(*objlist):
# hash each object given an raise TestFailed if
# the hash values are not all the same
hashed = map(hash, objlist)
for h in hashed[1:]:
if h != hashed[0]:
raise TestFailed, "hashed values differ: %s" % `objlist`
same_hash(1, 1L, 1.0, 1.0+0.0j)
same_hash(int(1), long(1), float(1), complex(1))
same_hash(long(1.23e300), float(1.23e300))
same_hash(float(0.5), complex(0.5, 0.0))