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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).
This commit is contained in:
Guido van Rossum 2002-07-16 20:24:46 +00:00
parent 6b6272c857
commit 613bed3726
1 changed files with 47 additions and 62 deletions
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97
Objects/iterobject.c
View File

@ -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)) {
@ -76,30 +70,26 @@ 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;
Py_DECREF(seq);
it->it_seq = NULL;
}
else {
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)
@ -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)
{
if (it->it_callable != NULL) {
PyObject *result = PyObject_CallObject(it->it_callable, NULL);
if (result != NULL) {
if (PyObject_RichCompareBool(result, it->it_sentinel, Py_EQ)) {
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;
}
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 */