SF patch 1546297 (with some tweaks):
Create a real zip iterator object; not using itertools.izip
(Brian Holmes).
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index cf839f4..dc4c583 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -230,3 +230,174 @@
(iternextfunc)calliter_iternext, /* tp_iternext */
0, /* tp_methods */
};
+
+
+/*********************** Zip Iterator **************************/
+/* Largely copied from itertools.c by Brian Holmes */
+
+typedef struct zipiterobject_t {
+ PyObject_HEAD
+ PyTupleObject *it_tuple; /* Set to NULL when iterator is exhausted */
+ Py_ssize_t resultsize;
+ PyTupleObject *result; /* Reusable tuple for optimization */
+} zipiterobject;
+
+static PyTypeObject PyZipIter_Type; /* Forward */
+
+PyObject *
+_PyZip_CreateIter(PyObject* args)
+{
+ Py_ssize_t i;
+ Py_ssize_t tuplesize;
+ PyObject* ziptuple;
+ PyObject* result;
+ struct zipiterobject_t* zipiter;
+
+ assert(PyTuple_Check(args));
+
+ if (PyZipIter_Type.ob_type == NULL) {
+ if (PyType_Ready(&PyZipIter_Type) < 0)
+ return NULL;
+ }
+
+ tuplesize = PySequence_Length((PyObject*) args);
+
+ ziptuple = PyTuple_New(tuplesize);
+ if (ziptuple == NULL)
+ return NULL;
+
+ for (i = 0; i < tuplesize; i++) {
+ PyObject *o = PyTuple_GET_ITEM(args, i);
+ PyObject *it = PyObject_GetIter(o);
+ if (it == NULL) {
+ /* XXX Should we do this?
+ if (PyErr_ExceptionMatches(PyExc_TypeError))
+ PyErr_Format(PyExc_TypeError,
+ "zip argument #%zd must support iteration",
+ I+1);
+ */
+ Py_DECREF(ziptuple);
+ return NULL;
+ }
+ PyTuple_SET_ITEM(ziptuple, i, it);
+ }
+
+ /* create a reusable result holder */
+ result = PyTuple_New(tuplesize);
+ if (result == NULL) {
+ Py_DECREF(ziptuple);
+ return NULL;
+ }
+ for (i = 0; i < tuplesize; i++) {
+ Py_INCREF(Py_None);
+ PyTuple_SET_ITEM(result, i, Py_None);
+ }
+
+ zipiter = PyObject_GC_New(zipiterobject, &PyZipIter_Type);
+ if (zipiter == NULL) {
+ Py_DECREF(ziptuple);
+ Py_DECREF(result);
+ return NULL;
+ }
+
+ zipiter->result = (PyTupleObject*) result;
+ zipiter->resultsize = tuplesize;
+ Py_INCREF(ziptuple);
+ zipiter->it_tuple = (PyTupleObject *) ziptuple;
+ _PyObject_GC_TRACK(zipiter);
+ return (PyObject *)zipiter;
+}
+
+static void
+zipiter_dealloc(zipiterobject *it)
+{
+ _PyObject_GC_UNTRACK(it);
+ Py_XDECREF(it->it_tuple);
+ Py_XDECREF(it->result);
+ PyObject_GC_Del(it);
+}
+
+static int
+zipiter_traverse(zipiterobject *it, visitproc visit, void *arg)
+{
+ Py_VISIT(it->it_tuple);
+ Py_VISIT(it->result);
+ return 0;
+}
+
+static PyObject *
+zipiter_next(zipiterobject *zit)
+{
+ Py_ssize_t i;
+ Py_ssize_t tuplesize = zit->resultsize;
+ PyObject *result = (PyObject*) zit->result;
+ PyObject *olditem;
+
+ if (tuplesize == 0)
+ return NULL;
+
+ if (result->ob_refcnt == 1) {
+ Py_INCREF(result);
+ for (i = 0; i < tuplesize; i++) {
+ PyObject *it = PyTuple_GET_ITEM(zit->it_tuple, i);
+ assert(PyIter_Check(it));
+ PyObject *item = (*it->ob_type->tp_iternext)(it);
+ if (item == NULL) {
+ Py_DECREF(result);
+ return NULL;
+ }
+ olditem = PyTuple_GET_ITEM(result, i);
+ PyTuple_SET_ITEM(result, i, item);
+ Py_DECREF(olditem);
+ }
+ } else {
+ result = PyTuple_New(tuplesize);
+ if (result == NULL)
+ return NULL;
+ for (i = 0; i < tuplesize; i++) {
+ PyObject *it = PyTuple_GET_ITEM(zit->it_tuple, i);
+ assert(PyIter_Check(it));
+ PyObject *item = (*it->ob_type->tp_iternext)(it);
+ if (item == NULL) {
+ Py_DECREF(result);
+ return NULL;
+ }
+ PyTuple_SET_ITEM(result, i, item);
+ }
+ }
+ return result;
+}
+
+static PyTypeObject PyZipIter_Type = {
+ PyObject_HEAD_INIT(0)
+ 0, /* ob_size */
+ "zipiterator", /* tp_name */
+ sizeof(zipiterobject), /* tp_basicsize */
+ 0, /* tp_itemsize */
+ /* methods */
+ (destructor)zipiter_dealloc, /* tp_dealloc */
+ 0, /* tp_print */
+ 0, /* tp_getattr */
+ 0, /* tp_setattr */
+ 0, /* tp_compare */
+ 0, /* tp_repr */
+ 0, /* tp_as_number */
+ 0, /* tp_as_sequence */
+ 0, /* tp_as_mapping */
+ 0, /* tp_hash */
+ 0, /* tp_call */
+ 0, /* tp_str */
+ PyObject_GenericGetAttr, /* tp_getattro */
+ 0, /* tp_setattro */
+ 0, /* tp_as_buffer */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
+ 0, /* tp_doc */
+ (traverseproc)zipiter_traverse, /* tp_traverse */
+ 0, /* tp_clear */
+ 0, /* tp_richcompare */
+ 0, /* tp_weakzipoffset */
+ PyObject_SelfIter, /* tp_iter */
+ (iternextfunc)zipiter_next, /* tp_iternext */
+ 0, /* tp_methods */
+ 0, /* tp_members */
+};