[Python-checkins] python/dist/src/Objects setobject.c,1.9,1.10

Sat Nov 22 21:49:07 EST 2003

Update of /cvsroot/python/python/dist/src/Objects
In directory sc8-pr-cvs1:/tmp/cvs-serv14916/Objects
Modified Files:
	setobject.c 
Log Message:
* Simplify hash function and add test to show effectiveness of the hash 
 function.
* Add a better test for deepcopying.
* Add tests to show the __init__() function works like it does for list
 and tuple. Add related test.
* Have shallow copies of frozensets return self. Add related test.
* Have frozenset(f) return f if f is already a frozenset. Add related test.
* Beefed-up some existing tests.
Index: setobject.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Objects/setobject.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -C2 -d -r1.9 -r1.10
*** setobject.c	22 Nov 2003 03:55:23 -0000	1.9
--- setobject.c	23 Nov 2003 02:49:05 -0000	1.10
***************
*** 65,68 ****
--- 65,72 ----
 	if (!PyArg_UnpackTuple(args, type->tp_name, 0, 1, &iterable))
 		return NULL;
+ 	if (iterable != NULL && iterable->ob_type == &PyFrozenSet_Type) {
+ 		Py_INCREF(iterable);
+ 		return iterable;
+ 	}
 	return make_new_set(type, iterable);
 }
***************
*** 155,158 ****
--- 159,172 ----
 }

+ static PyObject *
+ frozenset_copy(PySetObject *so)
+ {
+ 	if (so->ob_type == &PyFrozenSet_Type) {
+ 		Py_INCREF(so);
+ 		return (PyObject *)so;
+ 	}
+ 	return set_copy(so);
+ }
+ 
 PyDoc_STRVAR(copy_doc, "Return a shallow copy of a set.");

***************
*** 687,691 ****
 	PyObject *it, *item;
 	PySetObject *so = (PySetObject *)self;
! 	long hash = 0, x;

 	if (so->hash != -1)
--- 701,705 ----
 	PyObject *it, *item;
 	PySetObject *so = (PySetObject *)self;
! 	long hash = 0;

 	if (so->hash != -1)
***************
*** 697,708 ****

 	while ((item = PyIter_Next(it)) != NULL) {
! 		x = PyObject_Hash(item);
! 		/* Applying x*(x+1) breaks-up linear relationships so that
! 		 h(1) ^ h(2) will be less likely to coincide with hash(3).
! 		 Multiplying by a large prime increases the dispersion 
! 		 between consecutive hashes. Adding one bit from the 
! 		 original restores the one bit lost during the multiply 
! 		 (all the products are even numbers). */
! 		hash ^= (x * (x+1) * 3644798167) | (x&1);
 		Py_DECREF(item);
 	}
--- 711,720 ----

 	while ((item = PyIter_Next(it)) != NULL) {
! 		/* Multiplying by a large prime increases the bit dispersion for
! 		 closely spaced hash values. The is important because some
! 		 use cases have many combinations of a small number of 
! 		 elements with nearby hashes so that many distinct combinations
! 		 collapse to only a handful of distinct hash values. */
! 		hash ^= PyObject_Hash(item) * 3644798167;
 		Py_DECREF(item);
 	}
***************
*** 1097,1111 ****

 static PyMethodDef frozenset_methods[] = {
! 	{"copy",	(PyCFunction)set_copy,		METH_NOARGS,
 	 copy_doc},
! 	{"__copy__",	(PyCFunction)set_copy,		METH_NOARGS,
 	 copy_doc},
! 	{"difference",(PyCFunction)set_difference,	METH_O,
 	 difference_doc},
 	{"intersection",(PyCFunction)set_intersection,	METH_O,
 	 intersection_doc},
! 	{"issubset",(PyCFunction)set_issubset,		METH_O,
 	 issubset_doc},
! 	{"issuperset",(PyCFunction)set_issuperset,	METH_O,
 	 issuperset_doc},
 	{"__reduce__",	(PyCFunction)set_reduce,	METH_NOARGS,
--- 1109,1123 ----

 static PyMethodDef frozenset_methods[] = {
! 	{"copy",	(PyCFunction)frozenset_copy,	METH_NOARGS,
 	 copy_doc},
! 	{"__copy__",	(PyCFunction)frozenset_copy,	METH_NOARGS,
 	 copy_doc},
! 	{"difference",	(PyCFunction)set_difference,	METH_O,
 	 difference_doc},
 	{"intersection",(PyCFunction)set_intersection,	METH_O,
 	 intersection_doc},
! 	{"issubset",	(PyCFunction)set_issubset,	METH_O,
 	 issubset_doc},
! 	{"issuperset",	(PyCFunction)set_issuperset,	METH_O,
 	 issuperset_doc},
 	{"__reduce__",	(PyCFunction)set_reduce,	METH_NOARGS,