Issue #11707: Fast C version of functools.cmp_to_key()
This commit is contained in:
Raymond Hettinger
parent
271b27e5fe
commit
7ab9e22e34
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@ -97,7 +97,7 @@ def cmp_to_key(mycmp):
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"""Convert a cmp= function into a key= function"""
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class K(object):
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__slots__ = ['obj']
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def __init__(self, obj, *args):
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def __init__(self, obj):
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self.obj = obj
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def __lt__(self, other):
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return mycmp(self.obj, other.obj) < 0
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@ -115,6 +115,11 @@ def cmp_to_key(mycmp):
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raise TypeError('hash not implemented')
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return K
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try:
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from _functools import cmp_to_key
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except ImportError:
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pass
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_CacheInfo = namedtuple("CacheInfo", "hits misses maxsize currsize")
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def lru_cache(maxsize=100):
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@ -435,18 +435,81 @@ class TestReduce(unittest.TestCase):
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self.assertEqual(self.func(add, d), "".join(d.keys()))
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class TestCmpToKey(unittest.TestCase):
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def test_cmp_to_key(self):
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def cmp1(x, y):
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return (x > y) - (x < y)
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key = functools.cmp_to_key(cmp1)
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self.assertEqual(key(3), key(3))
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self.assertGreater(key(3), key(1))
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def cmp2(x, y):
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return int(x) - int(y)
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key = functools.cmp_to_key(cmp2)
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self.assertEqual(key(4.0), key('4'))
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self.assertLess(key(2), key('35'))
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def test_cmp_to_key_arguments(self):
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def cmp1(x, y):
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return (x > y) - (x < y)
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key = functools.cmp_to_key(mycmp=cmp1)
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self.assertEqual(key(obj=3), key(obj=3))
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self.assertGreater(key(obj=3), key(obj=1))
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with self.assertRaises((TypeError, AttributeError)):
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key(3) > 1 # rhs is not a K object
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with self.assertRaises((TypeError, AttributeError)):
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1 < key(3) # lhs is not a K object
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with self.assertRaises(TypeError):
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key = functools.cmp_to_key() # too few args
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with self.assertRaises(TypeError):
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key = functools.cmp_to_key(cmp1, None) # too many args
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key = functools.cmp_to_key(cmp1)
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with self.assertRaises(TypeError):
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key() # too few args
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with self.assertRaises(TypeError):
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key(None, None) # too many args
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def test_bad_cmp(self):
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def cmp1(x, y):
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raise ZeroDivisionError
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key = functools.cmp_to_key(cmp1)
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with self.assertRaises(ZeroDivisionError):
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key(3) > key(1)
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class BadCmp:
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def __lt__(self, other):
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raise ZeroDivisionError
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def cmp1(x, y):
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return BadCmp()
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with self.assertRaises(ZeroDivisionError):
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key(3) > key(1)
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def test_obj_field(self):
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def cmp1(x, y):
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return (x > y) - (x < y)
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key = functools.cmp_to_key(mycmp=cmp1)
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self.assertEqual(key(50).obj, 50)
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def test_sort_int(self):
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def mycmp(x, y):
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return y - x
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self.assertEqual(sorted(range(5), key=functools.cmp_to_key(mycmp)),
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[4, 3, 2, 1, 0])
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def test_sort_int_str(self):
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def mycmp(x, y):
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x, y = int(x), int(y)
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return (x > y) - (x < y)
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values = [5, '3', 7, 2, '0', '1', 4, '10', 1]
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values = sorted(values, key=functools.cmp_to_key(mycmp))
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self.assertEqual([int(value) for value in values],
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[0, 1, 1, 2, 3, 4, 5, 7, 10])
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def test_hash(self):
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def mycmp(x, y):
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return y - x
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key = functools.cmp_to_key(mycmp)
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k = key(10)
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self.assertRaises(TypeError, hash(k))
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self.assertRaises(TypeError, hash, k)
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class TestTotalOrdering(unittest.TestCase):
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@ -655,6 +718,7 @@ class TestLRU(unittest.TestCase):
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def test_main(verbose=None):
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test_classes = (
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TestCmpToKey,
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TestPartial,
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TestPartialSubclass,
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TestPythonPartial,
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@ -97,6 +97,9 @@ Library
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- Issue #10791: Implement missing method GzipFile.read1(), allowing GzipFile
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to be wrapped in a TextIOWrapper. Patch by Nadeem Vawda.
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- Issue #11707: Added a fast C version of functools.cmp_to_key().
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Patch by Filip Gruszczyński.
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- Issue #11688: Add sqlite3.Connection.set_trace_callback(). Patch by
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Torsten Landschoff.
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@ -330,6 +330,165 @@ static PyTypeObject partial_type = {
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};
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/* cmp_to_key ***************************************************************/
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typedef struct {
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PyObject_HEAD;
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PyObject *cmp;
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PyObject *object;
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} keyobject;
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static void
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keyobject_dealloc(keyobject *ko)
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{
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Py_DECREF(ko->cmp);
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Py_XDECREF(ko->object);
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PyObject_FREE(ko);
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}
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static int
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keyobject_traverse(keyobject *ko, visitproc visit, void *arg)
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{
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Py_VISIT(ko->cmp);
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if (ko->object)
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Py_VISIT(ko->object);
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return 0;
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}
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static PyMemberDef keyobject_members[] = {
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{"obj", T_OBJECT,
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offsetof(keyobject, object), 0,
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PyDoc_STR("Value wrapped by a key function.")},
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{NULL}
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};
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static PyObject *
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keyobject_call(keyobject *ko, PyObject *args, PyObject *kw);
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static PyObject *
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keyobject_richcompare(PyObject *ko, PyObject *other, int op);
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static PyTypeObject keyobject_type = {
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PyVarObject_HEAD_INIT(&PyType_Type, 0)
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"functools.KeyWrapper", /* tp_name */
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sizeof(keyobject), /* tp_basicsize */
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0, /* tp_itemsize */
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/* methods */
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(destructor)keyobject_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_reserved */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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(ternaryfunc)keyobject_call, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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0, /* tp_doc */
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(traverseproc)keyobject_traverse, /* tp_traverse */
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0, /* tp_clear */
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keyobject_richcompare, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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0, /* tp_iter */
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0, /* tp_iternext */
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0, /* tp_methods */
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keyobject_members, /* tp_members */
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0, /* tp_getset */
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};
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static PyObject *
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keyobject_call(keyobject *ko, PyObject *args, PyObject *kwds)
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{
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PyObject *object;
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keyobject *result;
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static char *kwargs[] = {"obj", NULL};
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:K", kwargs, &object))
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return NULL;
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result = PyObject_New(keyobject, &keyobject_type);
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if (!result)
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return NULL;
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Py_INCREF(ko->cmp);
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result->cmp = ko->cmp;
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Py_INCREF(object);
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result->object = object;
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return (PyObject *)result;
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}
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static PyObject *
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keyobject_richcompare(PyObject *ko, PyObject *other, int op)
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{
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PyObject *res;
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PyObject *args;
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PyObject *x;
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PyObject *y;
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PyObject *compare;
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PyObject *answer;
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static PyObject *zero;
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if (zero == NULL) {
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zero = PyLong_FromLong(0);
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if (!zero)
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return NULL;
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}
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if (Py_TYPE(other) != &keyobject_type){
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PyErr_Format(PyExc_TypeError, "other argument must be K instance");
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return NULL;
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}
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compare = ((keyobject *) ko)->cmp;
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assert(compare != NULL);
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x = ((keyobject *) ko)->object;
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y = ((keyobject *) other)->object;
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if (!x || !y){
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PyErr_Format(PyExc_AttributeError, "object");
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return NULL;
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}
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/* Call the user's comparison function and translate the 3-way
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* result into true or false (or error).
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*/
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args = PyTuple_New(2);
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if (args == NULL)
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return NULL;
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Py_INCREF(x);
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Py_INCREF(y);
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PyTuple_SET_ITEM(args, 0, x);
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PyTuple_SET_ITEM(args, 1, y);
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res = PyObject_Call(compare, args, NULL);
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Py_DECREF(args);
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if (res == NULL)
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return NULL;
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answer = PyObject_RichCompare(res, zero, op);
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Py_DECREF(res);
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return answer;
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}
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static PyObject *
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functools_cmp_to_key(PyObject *self, PyObject *args, PyObject *kwds){
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PyObject *cmp;
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static char *kwargs[] = {"mycmp", NULL};
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:cmp_to_key", kwargs, &cmp))
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return NULL;
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keyobject *object = PyObject_New(keyobject, &keyobject_type);
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if (!object)
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return NULL;
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Py_INCREF(cmp);
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object->cmp = cmp;
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object->object = NULL;
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return (PyObject *)object;
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}
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PyDoc_STRVAR(functools_cmp_to_key_doc,
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"Convert a cmp= function into a key= function.");
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/* reduce (used to be a builtin) ********************************************/
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static PyObject *
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@ -413,6 +572,8 @@ PyDoc_STRVAR(module_doc,
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static PyMethodDef module_methods[] = {
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{"reduce", functools_reduce, METH_VARARGS, functools_reduce_doc},
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{"cmp_to_key", functools_cmp_to_key, METH_VARARGS | METH_KEYWORDS,
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functools_cmp_to_key_doc},
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{NULL, NULL} /* sentinel */
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};
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