perform yield from delegation by repeating YIELD_FROM opcode (closes #14230)
This allows generators that are using yield from to be seen by debuggers. It
also kills the f_yieldfrom field on frame objects.
Patch mostly from Mark Shannon with a few tweaks by me.
diff --git a/Python/ceval.c b/Python/ceval.c
index 017dc4a..5498056 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1170,6 +1170,8 @@
f->f_lasti to -1 (i.e. the index *before* the first instruction)
and YIELD_VALUE doesn't fiddle with f_lasti any more. So this
does work. Promise.
+ YIELD_FROM sets f_lasti to itself, in order to repeated yield
+ multiple values.
When the PREDICT() macros are enabled, some opcode pairs follow in
direct succession without updating f->f_lasti. A successful
@@ -1830,49 +1832,35 @@
TARGET(YIELD_FROM)
u = POP();
- x = PyObject_GetIter(u);
+ x = TOP();
+ /* send u to x */
+ if (PyGen_CheckExact(x)) {
+ retval = _PyGen_Send((PyGenObject *)x, u);
+ } else {
+ if (u == Py_None)
+ retval = PyIter_Next(x);
+ else
+ retval = PyObject_CallMethod(x, "send", "O", u);
+ }
Py_DECREF(u);
- if (x == NULL)
- break;
- /* x is now the iterator, make the first next() call */
- retval = (*Py_TYPE(x)->tp_iternext)(x);
if (!retval) {
- PyObject *et, *ev, *tb;
- /* iter may be exhausted */
- Py_CLEAR(x);
- if (PyErr_Occurred() &&
- !PyErr_ExceptionMatches(PyExc_StopIteration)) {
- /* some other exception */
+ PyObject *val;
+ x = POP(); /* Remove iter from stack */
+ Py_DECREF(x);
+ err = PyGen_FetchStopIterationValue(&val);
+ if (err < 0) {
+ x = NULL;
break;
}
- /* try to get return value from exception */
- PyErr_Fetch(&et, &ev, &tb);
- Py_XDECREF(et);
- Py_XDECREF(tb);
- /* u is return value */
- u = NULL;
- if (ev) {
- u = PyObject_GetAttrString(ev, "value");
- Py_DECREF(ev);
- if (u == NULL) {
- if (!PyErr_ExceptionMatches(PyExc_AttributeError)) {
- /* some other exception */
- break;
- }
- PyErr_Clear();
- }
- }
- if (u == NULL) {
- u = Py_None;
- Py_INCREF(u);
- }
- PUSH(u);
+ x = val;
+ PUSH(x);
continue;
}
- /* x is iterator, retval is value to be yielded */
- f->f_yieldfrom = x;
+ /* x remains on stack, retval is value to be yielded */
f->f_stacktop = stack_pointer;
why = WHY_YIELD;
+ /* and repeat... */
+ f->f_lasti--;
goto fast_yield;
TARGET(YIELD_VALUE)