make PyIter_NextItem return 0 for exhausted iterator and 1 when it pr…

…ovides a new value
python · iritkatriel · Jun 1, 2023 · Jun 1, 2023 · Jun 1, 2023 · Jun 1, 2023
commit edc54c8507f0de242c7743452ab488c011591bdf
@@ -40,7 +40,7 @@ something like this::
 
    PyObject *item;
    int res;
-   while ((res = PyIter_NextItem(iterator, &item)) == 0 && item != NULL) {
+   while ((res = PyIter_NextItem(iterator, &item)) == 1) {
        /* do something with item */
        ...
        /* release reference when done */

diff --git a/Include/abstract.h b/Include/abstract.h
@@ -401,7 +401,8 @@ PyAPI_FUNC(int) PyAIter_Check(PyObject *);
    setting *item to the next value, or to NULL if the iterator
    is exhausted.
 
-   Return 0 on success and -1 on error. */
+   Return 1 if *item was set to a new value, 0 if the iterator is
+   exhausted and -1 on error. */
 PyAPI_FUNC(int) PyIter_NextItem(PyObject *iter, PyObject **item);
 
 /* Takes an iterator object and calls its tp_iternext slot,

diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
@@ -310,10 +310,14 @@ call_pyiter_nextitem(PyObject* self, PyObject *args)
     if (ret < 0) {
         return NULL;
     }
-    if (item == NULL) {
+    else if (ret == 0) {
+        assert(item == NULL);
         assert(!PyErr_Occurred());
         Py_RETURN_NONE;
     }
+    assert(ret == 1);
+    assert(item != NULL);
+    assert(!PyErr_Occurred());
     return item;
 }
 

@@ -377,7 +377,7 @@ static int fuzz_csv_reader(const char* data, size_t size) {
     if (reader) {
         /* Consume all of the reader as an iterator */
         PyObject* parsed_line;
-        while (PyIter_NextItem(reader, &parsed_line) == 0) {
+        while (PyIter_NextItem(reader, &parsed_line) == 1) {
             Py_DECREF(parsed_line);
         }
     }

diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -2833,9 +2833,10 @@ PyAIter_Check(PyObject *obj)
             tp->tp_as_async->am_anext != &_PyObject_NextNotImplemented);
 }
 
-/* Set *item to the next item. Return 0 on success and -1 on error.
- * If the iteration terminates normally, set *item to NULL and clear
- * the PyExc_StopIteration exception (if it was set).
+/* If the iterator has another value to return, set *item to this value
+ * and return 1.
+ * If the iterator is exhausted, set *item to NULL and return 0.
+ * On error (other than StopIteration) from tp_iternext, return -1.
  */
 int
 PyIter_NextItem(PyObject *iter, PyObject **item)
@@ -2852,8 +2853,9 @@ PyIter_NextItem(PyObject *iter, PyObject **item)
                 return -1;
             }
         }
+        return 0;
     }
-    return 0;
+    return 1;
 }
 
 /* Return next item.