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Fix for http://sourceforge.net/bugs/?func=detailbug&bug_id=111866&group_id=5470.

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This was a misleading bug -- the true "bug" was that hash(x) gave an error
return when x is an infinity.  Fixed that.  Added new Py_IS_INFINITY macro to
pyport.h.  Rearranged code to reduce growing duplication in hashing of float and
complex numbers, pushing Trent's earlier stab at that to a logical conclusion.
Fixed exceedingly rare bug where hashing of floats could return -1 even if there
wasn't an error (didn't waste time trying to construct a test case, it was simply
obvious from the code that it *could* happen).  Improved complex hash so that
hash(complex(x, y)) doesn't systematically equal hash(complex(y, x)) anymore.
This commit is contained in:
Tim Peters 2000-08-15 03:34:48 +00:00
parent 7aced17437
commit 39dce29365
5 changed files with 83 additions and 101 deletions
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63
Objects/complexobject.c
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@ -242,52 +242,23 @@ complex_compare(PyComplexObject *v, PyComplexObject *w)
static long
complex_hash(PyComplexObject *v)
{
double intpart, fractpart;
long x;
/* This is designed so that Python numbers with the same
value hash to the same value, otherwise comparisons
of mapping keys will turn out weird */
#ifdef MPW /* MPW C modf expects pointer to extended as second argument */
{
extended e;
fractpart = modf(v->cval.real, &e);
intpart = e;
}
#else
fractpart = modf(v->cval.real, &intpart);
#endif
if (fractpart == 0.0 && v->cval.imag == 0.0) {
if (intpart > LONG_MAX || -intpart > LONG_MAX) {
/* Convert to long int and use its hash... */
PyObject *w = PyLong_FromDouble(v->cval.real);
if (w == NULL)
return -1;
x = PyObject_Hash(w);
Py_DECREF(w);
return x;
}
x = (long)intpart;
}
else {
x = _Py_HashDouble(v->cval.real);
if (x == -1)
return -1;
if (v->cval.imag != 0.0) { /* Hash the imaginary part */
/* XXX Note that this hashes complex(x, y)
to the same value as complex(y, x).
Still better than it used to be :-) */
long y = _Py_HashDouble(v->cval.imag);
if (y == -1)
return -1;
x += y;
}
}
if (x == -1)
x = -2;
return x;
long hashreal, hashimag, combined;
hashreal = _Py_HashDouble(v->cval.real);
if (hashreal == -1)
return -1;
hashimag = _Py_HashDouble(v->cval.imag);
if (hashimag == -1)
return -1;
/* Note: if the imaginary part is 0, hashimag is 0 now,
* so the following returns hashreal unchanged. This is
* important because numbers of different types that
* 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;
}
static PyObject *