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Issue #6334: Fix buggy internal length calculation in builtin range function

This commit is contained in:
Mark Dickinson 2009-06-24 18:36:46 +00:00
parent eeb575f329
commit eb36d31bb8
2 changed files with 20 additions and 9 deletions
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18
Lib/test/test_builtin.py
View File

@ -924,6 +924,24 @@ class BuiltinTest(unittest.TestCase):
self.assertEqual(list(range(1, 10, 3)), [1, 4, 7])
#self.assertEqual(list(range(5, -5, -3)), [5, 2, -1, -4])
#issue 6334: the internal stored range length was being
#computed incorrectly in some cases involving large arguments.
x = range(10**20, 10**20+10, 3)
self.assertEqual(len(x), 4)
self.assertEqual(len(list(x)), 4)
x = range(10**20+10, 10**20, 3)
self.assertEqual(len(x), 0)
self.assertEqual(len(list(x)), 0)
x = range(10**20, 10**20+10, -3)
self.assertEqual(len(x), 0)
self.assertEqual(len(list(x)), 0)
x = range(10**20+10, 10**20, -3)
self.assertEqual(len(x), 4)
self.assertEqual(len(list(x)), 4)
""" XXX(nnorwitz):
# Now test range() with longs
self.assertEqual(list(range(-2**100)), [])

11
Objects/rangeobject.c
View File

@ -581,7 +581,6 @@ range_iter(PyObject *seq)
{
rangeobject *r = (rangeobject *)seq;
longrangeiterobject *it;
PyObject *tmp, *len;
long lstart, lstop, lstep;
assert(PyRange_Check(seq));
@ -612,15 +611,9 @@ range_iter(PyObject *seq)
it->len = it->index = NULL;
/* Calculate length: (r->stop - r->start) / r->step */
tmp = PyNumber_Subtract(r->stop, r->start);
if (!tmp)
it->len = range_length_obj(r);
if (!it->len)
goto create_failure;
len = PyNumber_FloorDivide(tmp, r->step);
Py_DECREF(tmp);
if (!len)
goto create_failure;
it->len = len;
it->index = PyLong_FromLong(0);
if (!it->index)
goto create_failure;