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perform yield from delegation by repeating YIELD_FROM opcode (closes #14230)

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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.
This commit is contained in:
Benjamin Peterson 2012-03-15 15:37:39 -05:00
parent 3270d11d8a
commit 2afe6aeae8
9 changed files with 113 additions and 166 deletions
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58
Python/ceval.c
View file

@ -1170,6 +1170,8 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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)

6
Python/compile.c
View file

@ -840,9 +840,9 @@ opcode_stack_effect(int opcode, int oparg)
case IMPORT_STAR:
return -1;
case YIELD_VALUE:
case YIELD_FROM:
return 0;
case YIELD_FROM:
return -1;
case POP_BLOCK:
return 0;
case POP_EXCEPT:
@ -3323,6 +3323,8 @@ compiler_visit_expr(struct compiler *c, expr_ty e)
ADDOP_O(c, LOAD_CONST, Py_None, consts);
}
if (e->kind == YieldFrom_kind) {
ADDOP(c, GET_ITER);
ADDOP_O(c, LOAD_CONST, Py_None, consts);
ADDOP(c, YIELD_FROM);
}
else {

3
Python/import.c
View file

@ -104,7 +104,8 @@ typedef unsigned short mode_t;
Python 3.2a2 3180 (add DELETE_DEREF)
Python 3.3a0 3190 __class__ super closure changed
Python 3.3a0 3200 (__qualname__ added)
3210 (added size modulo 2**32 to the pyc header)
Python 3.3a1 3210 (added size modulo 2**32 to the pyc header)
3220 (changed PEP 380 implementation)
*/
/* MAGIC must change whenever the bytecode emitted by the compiler may no