From 613bed3726af921be64900bd0cb8209193873411 Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Tue, 16 Jul 2002 20:24:46 +0000 Subject: [PATCH] Make StopIteration a sink state. This is done by clearing out the object references (it_seq for seqiterobject, it_callable and it_sentinel for calliterobject) when the end of the list is reached. Also remove the next() methods -- one is supplied automatically by PyType_Ready() because the tp_iternext slot is set. That's a good thing, because the implementation given here was buggy (it never raised StopIteration). --- Objects/iterobject.c | 109 +++++++++++++++++++------------------------ 1 file changed, 47 insertions(+), 62 deletions(-) diff --git a/Objects/iterobject.c b/Objects/iterobject.c index ce1fe3dc89d..447edbac503 100644 --- a/Objects/iterobject.c +++ b/Objects/iterobject.c @@ -5,7 +5,7 @@ typedef struct { PyObject_HEAD long it_index; - PyObject *it_seq; + PyObject *it_seq; /* Set to NULL when iterator is exhausted */ } seqiterobject; PyObject * @@ -26,31 +26,23 @@ PySeqIter_New(PyObject *seq) _PyObject_GC_TRACK(it); return (PyObject *)it; } + static void iter_dealloc(seqiterobject *it) { _PyObject_GC_UNTRACK(it); - Py_DECREF(it->it_seq); + Py_XDECREF(it->it_seq); PyObject_GC_Del(it); } static int iter_traverse(seqiterobject *it, visitproc visit, void *arg) { + if (it->it_seq == NULL) + return 0; return visit(it->it_seq, arg); } -static PyObject * -iter_next(seqiterobject *it) -{ - PyObject *seq = it->it_seq; - PyObject *result = PySequence_GetItem(seq, it->it_index++); - - if (result == NULL && PyErr_ExceptionMatches(PyExc_IndexError)) - PyErr_SetObject(PyExc_StopIteration, Py_None); - return result; -} - static PyObject * iter_getiter(PyObject *it) { @@ -67,6 +59,8 @@ iter_iternext(PyObject *iterator) assert(PySeqIter_Check(iterator)); it = (seqiterobject *)iterator; seq = it->it_seq; + if (seq == NULL) + return NULL; if (PyTuple_CheckExact(seq)) { if (it->it_index < PyTuple_GET_SIZE(seq)) { @@ -76,31 +70,27 @@ iter_iternext(PyObject *iterator) Py_INCREF(item); return item; } + Py_DECREF(seq); + it->it_seq = NULL; return NULL; } else { - PyObject *result = PySequence_ITEM(seq, it->it_index); - it->it_index++; + PyObject *result = PySequence_GetItem(seq, it->it_index); if (result != NULL) { + it->it_index++; return result; } if (PyErr_ExceptionMatches(PyExc_IndexError) || - PyErr_ExceptionMatches(PyExc_StopIteration)) { + PyErr_ExceptionMatches(PyExc_StopIteration)) + { PyErr_Clear(); - return NULL; - } - else { - return NULL; + Py_DECREF(seq); + it->it_seq = NULL; } + return NULL; } } -static PyMethodDef iter_methods[] = { - {"next", (PyCFunction)iter_next, METH_NOARGS, - "it.next() -- get the next value, or raise StopIteration"}, - {NULL, NULL} /* sentinel */ -}; - PyTypeObject PySeqIter_Type = { PyObject_HEAD_INIT(&PyType_Type) 0, /* ob_size */ @@ -131,7 +121,7 @@ PyTypeObject PySeqIter_Type = { 0, /* tp_weaklistoffset */ (getiterfunc)iter_getiter, /* tp_iter */ (iternextfunc)iter_iternext, /* tp_iternext */ - iter_methods, /* tp_methods */ + 0, /* tp_methods */ 0, /* tp_members */ 0, /* tp_getset */ 0, /* tp_base */ @@ -144,8 +134,8 @@ PyTypeObject PySeqIter_Type = { typedef struct { PyObject_HEAD - PyObject *it_callable; - PyObject *it_sentinel; + PyObject *it_callable; /* Set to NULL when iterator is exhausted */ + PyObject *it_sentinel; /* Set to NULL when iterator is exhausted */ } calliterobject; PyObject * @@ -166,8 +156,8 @@ static void calliter_dealloc(calliterobject *it) { _PyObject_GC_UNTRACK(it); - Py_DECREF(it->it_callable); - Py_DECREF(it->it_sentinel); + Py_XDECREF(it->it_callable); + Py_XDECREF(it->it_sentinel); PyObject_GC_Del(it); } @@ -175,47 +165,42 @@ static int calliter_traverse(calliterobject *it, visitproc visit, void *arg) { int err; - if ((err = visit(it->it_callable, arg))) + if (it->it_callable != NULL && (err = visit(it->it_callable, arg))) return err; - if ((err = visit(it->it_sentinel, arg))) + if (it->it_sentinel != NULL && (err = visit(it->it_sentinel, arg))) return err; return 0; } -static PyObject * -calliter_next(calliterobject *it, PyObject *args) -{ - PyObject *result = PyObject_CallObject(it->it_callable, NULL); - if (result != NULL) { - if (PyObject_RichCompareBool(result, it->it_sentinel, Py_EQ)) { - PyErr_SetObject(PyExc_StopIteration, Py_None); - Py_DECREF(result); - result = NULL; - } - } - return result; -} - -static PyMethodDef calliter_methods[] = { - {"next", (PyCFunction)calliter_next, METH_VARARGS, - "it.next() -- get the next value, or raise StopIteration"}, - {NULL, NULL} /* sentinel */ -}; - static PyObject * calliter_iternext(calliterobject *it) { - PyObject *result = PyObject_CallObject(it->it_callable, NULL); - if (result != NULL) { - if (PyObject_RichCompareBool(result, it->it_sentinel, Py_EQ)) { + if (it->it_callable != NULL) { + PyObject *result = PyObject_CallObject(it->it_callable, NULL); + if (result != NULL) { + int ok; + ok = PyObject_RichCompareBool(result, + it->it_sentinel, + Py_EQ); + if (ok == 0) + return result; /* Common case, fast path */ Py_DECREF(result); - result = NULL; + if (ok > 0) { + Py_DECREF(it->it_callable); + it->it_callable = NULL; + Py_DECREF(it->it_sentinel); + it->it_sentinel = NULL; + } + } + else if (PyErr_ExceptionMatches(PyExc_StopIteration)) { + PyErr_Clear(); + Py_DECREF(it->it_callable); + it->it_callable = NULL; + Py_DECREF(it->it_sentinel); + it->it_sentinel = NULL; } } - else if (PyErr_ExceptionMatches(PyExc_StopIteration)) { - PyErr_Clear(); - } - return result; + return NULL; } PyTypeObject PyCallIter_Type = { @@ -248,7 +233,7 @@ PyTypeObject PyCallIter_Type = { 0, /* tp_weaklistoffset */ (getiterfunc)iter_getiter, /* tp_iter */ (iternextfunc)calliter_iternext, /* tp_iternext */ - calliter_methods, /* tp_methods */ + 0, /* tp_methods */ 0, /* tp_members */ 0, /* tp_getset */ 0, /* tp_base */