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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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56
Python/sysmodule.c
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@ -570,6 +570,57 @@ sys_setrecursionlimit(PyObject *self, PyObject *args)
return Py_None;
}
static PyTypeObject Hash_InfoType;
PyDoc_STRVAR(hash_info_doc,
"hash_info\n\
\n\
A struct sequence providing parameters used for computing\n\
numeric hashes. The attributes are read only.");
static PyStructSequence_Field hash_info_fields[] = {
{"width", "width of the type used for hashing, in bits"},
{"modulus", "prime number giving the modulus on which the hash "
"function is based"},
{"inf", "value to be used for hash of a positive infinity"},
{"nan", "value to be used for hash of a nan"},
{"imag", "multiplier used for the imaginary part of a complex number"},
{NULL, NULL}
};
static PyStructSequence_Desc hash_info_desc = {
"sys.hash_info",
hash_info_doc,
hash_info_fields,
5,
};
PyObject *
get_hash_info(void)
{
PyObject *hash_info;
int field = 0;
hash_info = PyStructSequence_New(&Hash_InfoType);
if (hash_info == NULL)
return NULL;
PyStructSequence_SET_ITEM(hash_info, field++,
PyLong_FromLong(8*sizeof(long)));
PyStructSequence_SET_ITEM(hash_info, field++,
PyLong_FromLong(_PyHASH_MODULUS));
PyStructSequence_SET_ITEM(hash_info, field++,
PyLong_FromLong(_PyHASH_INF));
PyStructSequence_SET_ITEM(hash_info, field++,
PyLong_FromLong(_PyHASH_NAN));
PyStructSequence_SET_ITEM(hash_info, field++,
PyLong_FromLong(_PyHASH_IMAG));
if (PyErr_Occurred()) {
Py_CLEAR(hash_info);
return NULL;
}
return hash_info;
}
PyDoc_STRVAR(setrecursionlimit_doc,
"setrecursionlimit(n)\n\
\n\
@ -1482,6 +1533,11 @@ _PySys_Init(void)
PyFloat_GetInfo());
SET_SYS_FROM_STRING("int_info",
PyLong_GetInfo());
/* initialize hash_info */
if (Hash_InfoType.tp_name == 0)
PyStructSequence_InitType(&Hash_InfoType, &hash_info_desc);
SET_SYS_FROM_STRING("hash_info",
get_hash_info());
SET_SYS_FROM_STRING("maxunicode",
PyLong_FromLong(PyUnicode_GetMax()));
SET_SYS_FROM_STRING("builtin_module_names",