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bpo-36781: Optimize sum() for bools. (#13074) 

* Optimize sum() for bools.

* Fix sum([], False).

* Add a NEWS entry.
This commit is contained in:
Serhiy Storchaka 2019-09-10 16:31:01 +03:00 committed by Dino Viehland
parent c1d8c1cb8e
commit 88bdb9280b
3 changed files with 24 additions and 2 deletions
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21
Lib/test/test_builtin.py
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@ -1373,6 +1373,24 @@ class BuiltinTest(unittest.TestCase):
self.assertEqual(sum(range(10), 1000), 1045) self.assertEqual(sum(range(10), 1000), 1045)
self.assertEqual(sum(range(10), start=1000), 1045) self.assertEqual(sum(range(10), start=1000), 1045)
self.assertEqual(sum(range(10), 2**31-5), 2**31+40)
self.assertEqual(sum(range(10), 2**63-5), 2**63+40)
self.assertEqual(sum(i % 2 != 0 for i in range(10)), 5)
self.assertEqual(sum((i % 2 != 0 for i in range(10)), 2**31-3),
2**31+2)
self.assertEqual(sum((i % 2 != 0 for i in range(10)), 2**63-3),
2**63+2)
self.assertIs(sum([], False), False)
self.assertEqual(sum(i / 2 for i in range(10)), 22.5)
self.assertEqual(sum((i / 2 for i in range(10)), 1000), 1022.5)
self.assertEqual(sum((i / 2 for i in range(10)), 1000.25), 1022.75)
self.assertEqual(sum([0.5, 1]), 1.5)
self.assertEqual(sum([1, 0.5]), 1.5)
self.assertEqual(repr(sum([-0.0])), '0.0')
self.assertEqual(repr(sum([-0.0], -0.0)), '-0.0')
self.assertEqual(repr(sum([], -0.0)), '-0.0')
self.assertRaises(TypeError, sum) self.assertRaises(TypeError, sum)
self.assertRaises(TypeError, sum, 42) self.assertRaises(TypeError, sum, 42)
@ -1384,6 +1402,9 @@ class BuiltinTest(unittest.TestCase):
self.assertRaises(TypeError, sum, [[1], [2], [3]]) self.assertRaises(TypeError, sum, [[1], [2], [3]])
self.assertRaises(TypeError, sum, [{2:3}]) self.assertRaises(TypeError, sum, [{2:3}])
self.assertRaises(TypeError, sum, [{2:3}]*2, {2:3}) self.assertRaises(TypeError, sum, [{2:3}]*2, {2:3})
self.assertRaises(TypeError, sum, [], '')
self.assertRaises(TypeError, sum, [], b'')
self.assertRaises(TypeError, sum, [], bytearray())
class BadSeq: class BadSeq:
def __getitem__(self, index): def __getitem__(self, index):

1
Misc/NEWS.d/next/Core and Builtins/2019-05-06-09-59-31.bpo-36781.uocWt6.rst Normal file
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@ -0,0 +1 @@
:func:`sum` has been optimized for boolean values.

4
Python/bltinmodule.c
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@ -2342,7 +2342,7 @@ builtin_sum_impl(PyObject *module, PyObject *iterable, PyObject *start)
return NULL; return NULL;
return PyLong_FromLong(i_result); return PyLong_FromLong(i_result);
} }
if (PyLong_CheckExact(item)) { if (PyLong_CheckExact(item) || PyBool_Check(item)) {
long b = PyLong_AsLongAndOverflow(item, &overflow); long b = PyLong_AsLongAndOverflow(item, &overflow);
if (overflow == 0 && if (overflow == 0 &&
(i_result >= 0 ? (b <= LONG_MAX - i_result) (i_result >= 0 ? (b <= LONG_MAX - i_result)
@ -2390,7 +2390,7 @@ builtin_sum_impl(PyObject *module, PyObject *iterable, PyObject *start)
Py_DECREF(item); Py_DECREF(item);
continue; continue;
} }
if (PyLong_CheckExact(item)) { if (PyLong_Check(item)) {
long value; long value;
int overflow; int overflow;
value = PyLong_AsLongAndOverflow(item, &overflow); value = PyLong_AsLongAndOverflow(item, &overflow);