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bpo-35664: Optimize operator.itemgetter (GH-11435)

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Raymond Hettinger 2019-01-07 09:38:41 -07:00 • committed by GitHub
parent 3f7983a25a
commit 2d53bed79c
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3 changed files with 54 additions and 5 deletions
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42
Modules/_operator.c
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@ -937,6 +937,7 @@ typedef struct {
PyObject_HEAD
Py_ssize_t nitems;
PyObject *item;
Py_ssize_t index; // -1 unless *item* is a single non-negative integer index
} itemgetterobject;
static PyTypeObject itemgetter_type;
@ -948,6 +949,7 @@ itemgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
itemgetterobject *ig;
PyObject *item;
Py_ssize_t nitems;
Py_ssize_t index;
if (!_PyArg_NoKeywords("itemgetter", kwds))
return NULL;
@ -967,6 +969,21 @@ itemgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
Py_INCREF(item);
ig->item = item;
ig->nitems = nitems;
ig->index = -1;
if (PyLong_CheckExact(item)) {
index = PyLong_AsSsize_t(item);
if (index < 0) {
/* If we get here, then either the index conversion failed
* due to being out of range, or the index was a negative
* integer. Either way, we clear any possible exception
* and fall back to the slow path, where ig->index is -1.
*/
PyErr_Clear();
}
else {
ig->index = index;
}
}
PyObject_GC_Track(ig);
return (PyObject *)ig;
@ -993,12 +1010,27 @@ itemgetter_call(itemgetterobject *ig, PyObject *args, PyObject *kw)
PyObject *obj, *result;
Py_ssize_t i, nitems=ig->nitems;
if (!_PyArg_NoKeywords("itemgetter", kw))
return NULL;
if (!PyArg_UnpackTuple(args, "itemgetter", 1, 1, &obj))
return NULL;
if (nitems == 1)
assert(PyTuple_CheckExact(args));
if (kw == NULL && PyTuple_GET_SIZE(args) == 1) {
obj = PyTuple_GET_ITEM(args, 0);
}
else {
if (!_PyArg_NoKeywords("itemgetter", kw))
return NULL;
if (!PyArg_UnpackTuple(args, "itemgetter", 1, 1, &obj))
return NULL;
}
if (nitems == 1) {
if (ig->index >= 0
&& PyTuple_CheckExact(obj)
&& ig->index < PyTuple_GET_SIZE(obj))
{
result = PyTuple_GET_ITEM(obj, ig->index);
Py_INCREF(result);
return result;
}
return PyObject_GetItem(obj, ig->item);
}
assert(PyTuple_Check(ig->item));
assert(PyTuple_GET_SIZE(ig->item) == nitems);