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

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(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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14
Include/pyport.h
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@ -126,6 +126,20 @@ Used in: PY_LONG_LONG
#endif
#endif
/* Parameters used for the numeric hash implementation. See notes for
_PyHash_Double in Objects/object.c. Numeric hashes are based on
reduction modulo the prime 2**_PyHASH_BITS - 1. */
#if SIZEOF_LONG >= 8
#define _PyHASH_BITS 61
#else
#define _PyHASH_BITS 31
#endif
#define _PyHASH_MODULUS ((1UL << _PyHASH_BITS) - 1)
#define _PyHASH_INF 314159
#define _PyHASH_NAN 0
#define _PyHASH_IMAG 1000003UL
/* uintptr_t is the C9X name for an unsigned integral type such that a
* legitimate void* can be cast to uintptr_t and then back to void* again
* without loss of information. Similarly for intptr_t, wrt a signed