diff options
| -rw-r--r-- | Lib/test/test_itertools.py | 5 | ||||
| -rw-r--r-- | Misc/NEWS | 4 | ||||
| -rw-r--r-- | Modules/itertoolsmodule.c | 7 |
3 files changed, 13 insertions, 3 deletions
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py index 06777a1..fe6131a 100644 --- a/Lib/test/test_itertools.py +++ b/Lib/test/test_itertools.py @@ -788,6 +788,11 @@ class TestBasicOps(unittest.TestCase): self.assertRaises(ValueError, islice, range(10), 1, 'a', 1) self.assertEqual(len(list(islice(count(), 1, 10, maxsize))), 1) + # Issue #10323: Less islice in a predictable state + c = count() + self.assertEqual(list(islice(c, 1, 3, 50)), [1]) + self.assertEqual(next(c), 3) + def test_takewhile(self): data = [1, 3, 5, 20, 2, 4, 6, 8] underten = lambda x: x<10 @@ -43,6 +43,10 @@ Core and Builtins Library ------- +- Issue #10323: itertools.islice() now consumes the minimum number of + inputs before stopping. Formerly, the final state of the underlying + iterator was undefined. + - Issue #10565: The collections.Iterator ABC now checks for both __iter__ and __next__. diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c index ba8d6df..d5336f2 100644 --- a/Modules/itertoolsmodule.c +++ b/Modules/itertoolsmodule.c @@ -1215,6 +1215,7 @@ islice_next(isliceobject *lz) { PyObject *item; PyObject *it = lz->it; + Py_ssize_t stop = lz->stop; Py_ssize_t oldnext; PyObject *(*iternext)(PyObject *); @@ -1226,7 +1227,7 @@ islice_next(isliceobject *lz) Py_DECREF(item); lz->cnt++; } - if (lz->stop != -1 && lz->cnt >= lz->stop) + if (stop != -1 && lz->cnt >= stop) return NULL; item = iternext(it); if (item == NULL) @@ -1234,8 +1235,8 @@ islice_next(isliceobject *lz) lz->cnt++; oldnext = lz->next; lz->next += lz->step; - if (lz->next < oldnext) /* Check for overflow */ - lz->next = lz->stop; + if (lz->next < oldnext || (stop != -1 && lz->next > stop)) + lz->next = stop; return item; } |