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Issue #8188: Introduce a new scheme for computing hashes of numbers

Browse source 
(instances of int, float, complex, decimal.Decimal and
fractions.Fraction) that makes it easy to maintain the invariant that
hash(x) == hash(y) whenever x and y have equal value.
This commit is contained in:
Mark Dickinson 2010-05-23 13:33:13 +00:00
parent 03721133a6
commit dc787d2055
14 changed files with 566 additions and 137 deletions
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18
Objects/complexobject.c
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@ -403,12 +403,12 @@ complex_str(PyComplexObject *v)
static long
complex_hash(PyComplexObject *v)
{
long hashreal, hashimag, combined;
hashreal = _Py_HashDouble(v->cval.real);
if (hashreal == -1)
unsigned long hashreal, hashimag, combined;
hashreal = (unsigned long)_Py_HashDouble(v->cval.real);
if (hashreal == (unsigned long)-1)
return -1;
hashimag = _Py_HashDouble(v->cval.imag);
if (hashimag == -1)
hashimag = (unsigned long)_Py_HashDouble(v->cval.imag);
if (hashimag == (unsigned long)-1)
return -1;
/* Note: if the imaginary part is 0, hashimag is 0 now,
* so the following returns hashreal unchanged. This is
@ -416,10 +416,10 @@ complex_hash(PyComplexObject *v)
* compare equal must have the same hash value, so that
* hash(x + 0*j) must equal hash(x).
*/
combined = hashreal + 1000003 * hashimag;
if (combined == -1)
combined = -2;
return combined;
combined = hashreal + _PyHASH_IMAG * hashimag;
if (combined == (unsigned long)-1)
combined = (unsigned long)-2;
return (long)combined;
}
/* This macro may return! */