diff --git a/Lib/test/test_operator.py b/Lib/test/test_operator.py index 6254091e78f..f46d94a2267 100644 --- a/Lib/test/test_operator.py +++ b/Lib/test/test_operator.py @@ -401,6 +401,19 @@ class OperatorTestCase: self.assertEqual(operator.itemgetter(2,10,5)(data), ('2', '10', '5')) self.assertRaises(TypeError, operator.itemgetter(2, 'x', 5), data) + # interesting indices + t = tuple('abcde') + self.assertEqual(operator.itemgetter(-1)(t), 'e') + self.assertEqual(operator.itemgetter(slice(2, 4))(t), ('c', 'd')) + + # interesting sequences + class T(tuple): + 'Tuple subclass' + pass + self.assertEqual(operator.itemgetter(0)(T('abc')), 'a') + self.assertEqual(operator.itemgetter(0)(['a', 'b', 'c']), 'a') + self.assertEqual(operator.itemgetter(0)(range(100, 200)), 100) + def test_methodcaller(self): operator = self.module self.assertRaises(TypeError, operator.methodcaller) diff --git a/Misc/NEWS.d/next/Library/2019-01-04-22-18-25.bpo-35664.Z-Gyyj.rst b/Misc/NEWS.d/next/Library/2019-01-04-22-18-25.bpo-35664.Z-Gyyj.rst new file mode 100644 index 00000000000..f4acc5ae57e --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-01-04-22-18-25.bpo-35664.Z-Gyyj.rst @@ -0,0 +1,4 @@ +Improve operator.itemgetter() performance by 33% with optimized argument +handling and with adding a fast path for the common case of a single +non-negative integer index into a tuple (which is the typical use case in +the standard library). diff --git a/Modules/_operator.c b/Modules/_operator.c index 3bf8c1276d7..d6c6a18d81b 100644 --- a/Modules/_operator.c +++ b/Modules/_operator.c @@ -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);