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Issue #11707: Fast C version of functools.cmp_to_key()

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This commit is contained in:
Raymond Hettinger 2011-04-05 02:33:54 -07:00
parent 271b27e5fe
commit 7ab9e22e34
4 changed files with 235 additions and 2 deletions
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161
Modules/_functoolsmodule.c
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@ -330,6 +330,165 @@ static PyTypeObject partial_type = {
};
/* cmp_to_key ***************************************************************/
typedef struct {
PyObject_HEAD;
PyObject *cmp;
PyObject *object;
} keyobject;
static void
keyobject_dealloc(keyobject *ko)
{
Py_DECREF(ko->cmp);
Py_XDECREF(ko->object);
PyObject_FREE(ko);
}
static int
keyobject_traverse(keyobject *ko, visitproc visit, void *arg)
{
Py_VISIT(ko->cmp);
if (ko->object)
Py_VISIT(ko->object);
return 0;
}
static PyMemberDef keyobject_members[] = {
{"obj", T_OBJECT,
offsetof(keyobject, object), 0,
PyDoc_STR("Value wrapped by a key function.")},
{NULL}
};
static PyObject *
keyobject_call(keyobject *ko, PyObject *args, PyObject *kw);
static PyObject *
keyobject_richcompare(PyObject *ko, PyObject *other, int op);
static PyTypeObject keyobject_type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"functools.KeyWrapper", /* tp_name */
sizeof(keyobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)keyobject_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
(ternaryfunc)keyobject_call, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
(traverseproc)keyobject_traverse, /* tp_traverse */
0, /* tp_clear */
keyobject_richcompare, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
0, /* tp_methods */
keyobject_members, /* tp_members */
0, /* tp_getset */
};
static PyObject *
keyobject_call(keyobject *ko, PyObject *args, PyObject *kwds)
{
PyObject *object;
keyobject *result;
static char *kwargs[] = {"obj", NULL};
if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:K", kwargs, &object))
return NULL;
result = PyObject_New(keyobject, &keyobject_type);
if (!result)
return NULL;
Py_INCREF(ko->cmp);
result->cmp = ko->cmp;
Py_INCREF(object);
result->object = object;
return (PyObject *)result;
}
static PyObject *
keyobject_richcompare(PyObject *ko, PyObject *other, int op)
{
PyObject *res;
PyObject *args;
PyObject *x;
PyObject *y;
PyObject *compare;
PyObject *answer;
static PyObject *zero;
if (zero == NULL) {
zero = PyLong_FromLong(0);
if (!zero)
return NULL;
}
if (Py_TYPE(other) != &keyobject_type){
PyErr_Format(PyExc_TypeError, "other argument must be K instance");
return NULL;
}
compare = ((keyobject *) ko)->cmp;
assert(compare != NULL);
x = ((keyobject *) ko)->object;
y = ((keyobject *) other)->object;
if (!x || !y){
PyErr_Format(PyExc_AttributeError, "object");
return NULL;
}
/* Call the user's comparison function and translate the 3-way
* result into true or false (or error).
*/
args = PyTuple_New(2);
if (args == NULL)
return NULL;
Py_INCREF(x);
Py_INCREF(y);
PyTuple_SET_ITEM(args, 0, x);
PyTuple_SET_ITEM(args, 1, y);
res = PyObject_Call(compare, args, NULL);
Py_DECREF(args);
if (res == NULL)
return NULL;
answer = PyObject_RichCompare(res, zero, op);
Py_DECREF(res);
return answer;
}
static PyObject *
functools_cmp_to_key(PyObject *self, PyObject *args, PyObject *kwds){
PyObject *cmp;
static char *kwargs[] = {"mycmp", NULL};
if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:cmp_to_key", kwargs, &cmp))
return NULL;
keyobject *object = PyObject_New(keyobject, &keyobject_type);
if (!object)
return NULL;
Py_INCREF(cmp);
object->cmp = cmp;
object->object = NULL;
return (PyObject *)object;
}
PyDoc_STRVAR(functools_cmp_to_key_doc,
"Convert a cmp= function into a key= function.");
/* reduce (used to be a builtin) ********************************************/
static PyObject *
@ -413,6 +572,8 @@ PyDoc_STRVAR(module_doc,
static PyMethodDef module_methods[] = {
{"reduce", functools_reduce, METH_VARARGS, functools_reduce_doc},
{"cmp_to_key", functools_cmp_to_key, METH_VARARGS | METH_KEYWORDS,
functools_cmp_to_key_doc},
{NULL, NULL} /* sentinel */
};