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Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted.

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Patch by Anton Afanasyev.
This commit is contained in:
Antoine Pitrou 2014-04-29 12:14:47 +02:00
commit 32497f89bb
4 changed files with 37 additions and 5 deletions
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25
Modules/itertoolsmodule.c
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@ -1492,19 +1492,22 @@ islice_next(isliceobject *lz)
Py_ssize_t oldnext;
PyObject *(*iternext)(PyObject *);
if (it == NULL)
return NULL;
iternext = *Py_TYPE(it)->tp_iternext;
while (lz->cnt < lz->next) {
item = iternext(it);
if (item == NULL)
return NULL;
goto empty;
Py_DECREF(item);
lz->cnt++;
}
if (stop != -1 && lz->cnt >= stop)
return NULL;
goto empty;
item = iternext(it);
if (item == NULL)
return NULL;
goto empty;
lz->cnt++;
oldnext = lz->next;
/* The (size_t) cast below avoids the danger of undefined
@ -1513,6 +1516,10 @@ islice_next(isliceobject *lz)
if (lz->next < oldnext || (stop != -1 && lz->next > stop))
lz->next = stop;
return item;
empty:
Py_CLEAR(lz->it);
return NULL;
}
static PyObject *
@ -1522,6 +1529,18 @@ islice_reduce(isliceobject *lz)
* then 'setstate' with the next and count
*/
PyObject *stop;
if (lz->it == NULL) {
PyObject *empty_list;
PyObject *empty_it;
empty_list = PyList_New(0);
if (empty_list == NULL)
return NULL;
empty_it = PyObject_GetIter(empty_list);
Py_DECREF(empty_list);
if (empty_it == NULL)
return NULL;
return Py_BuildValue("O(Nn)n", Py_TYPE(lz), empty_it, 0, 0);
}
if (lz->stop == -1) {
stop = Py_None;
Py_INCREF(stop);