# 关键源码
# PyGenObject
/* _PyGenObject_HEAD defines the initial segment of generator
and coroutine objects. */
#define _PyGenObject_HEAD(prefix) \
PyObject_HEAD \
/* Note: gi_frame can be NULL if the generator is "finished" */ \
struct _frame *prefix##_frame; \
/* True if generator is being executed. */ \
char prefix##_running; \
/* The code object backing the generator */ \
PyObject *prefix##_code; \
/* List of weak reference. */ \
PyObject *prefix##_weakreflist; \
/* Name of the generator. */ \
PyObject *prefix##_name; \
/* Qualified name of the generator. */ \
PyObject *prefix##_qualname; \
_PyErr_StackItem prefix##_exc_state;
typedef struct {
/* The gi_ prefix is intended to remind of generator-iterator. */
_PyGenObject_HEAD(gi)
} PyGenObject;
# PyGen_Type
PyTypeObject PyGen_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"generator", /* tp_name */
sizeof(PyGenObject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)gen_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
(reprfunc)gen_repr, /* 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 |
Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
0, /* tp_doc */
(traverseproc)gen_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)gen_iternext, /* tp_iternext */
gen_methods, /* tp_methods */
gen_memberlist, /* tp_members */
gen_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
0, /* tp_free */
0, /* tp_is_gc */
0, /* tp_bases */
0, /* tp_mro */
0, /* tp_cache */
0, /* tp_subclasses */
0, /* tp_weaklist */
0, /* tp_del */
0, /* tp_version_tag */
_PyGen_Finalize, /* tp_finalize */
};
# builtin_next
static PyObject *
builtin_next(PyObject *self, PyObject *const *args, Py_ssize_t nargs)
{
PyObject *it, *res;
PyObject *def = NULL;
if (!_PyArg_UnpackStack(args, nargs, "next", 1, 2, &it, &def))
return NULL;
if (!PyIter_Check(it)) {
PyErr_Format(PyExc_TypeError,
"'%.200s' object is not an iterator",
it->ob_type->tp_name);
return NULL;
}
res = (*it->ob_type->tp_iternext)(it); // 关键之处
if (res != NULL) {
return res;
} else if (def != NULL) {
if (PyErr_Occurred()) {
if(!PyErr_ExceptionMatches(PyExc_StopIteration))
return NULL;
PyErr_Clear();
}
Py_INCREF(def);
return def;
} else if (PyErr_Occurred()) {
return NULL;
} else {
PyErr_SetNone(PyExc_StopIteration);
return NULL;
}
}
# gen_iternext
static PyObject *
gen_iternext(PyGenObject *gen)
{
return gen_send_ex(gen, NULL, 0, 0);
}
# gen_send_ex
static PyObject *
gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
{
PyThreadState *tstate = PyThreadState_GET();
PyFrameObject *f = gen->gi_frame;
PyObject *result;
if (gen->gi_running) {
const char *msg = "generator already executing";
if (PyCoro_CheckExact(gen)) {
msg = "coroutine already executing";
}
else if (PyAsyncGen_CheckExact(gen)) {
msg = "async generator already executing";
}
PyErr_SetString(PyExc_ValueError, msg);
return NULL;
}
if (f == NULL || f->f_stacktop == NULL) {
if (PyCoro_CheckExact(gen) && !closing) {
/* `gen` is an exhausted coroutine: raise an error,
except when called from gen_close(), which should
always be a silent method. */
PyErr_SetString(
PyExc_RuntimeError,
"cannot reuse already awaited coroutine");
}
else if (arg && !exc) {
/* `gen` is an exhausted generator:
only set exception if called from send(). */
if (PyAsyncGen_CheckExact(gen)) {
PyErr_SetNone(PyExc_StopAsyncIteration);
}
else {
PyErr_SetNone(PyExc_StopIteration);
}
}
return NULL;
}
if (f->f_lasti == -1) {
if (arg && arg != Py_None) {
const char *msg = "can't send non-None value to a "
"just-started generator";
if (PyCoro_CheckExact(gen)) {
msg = NON_INIT_CORO_MSG;
}
else if (PyAsyncGen_CheckExact(gen)) {
msg = "can't send non-None value to a "
"just-started async generator";
}
PyErr_SetString(PyExc_TypeError, msg);
return NULL;
}
} else {
/* Push arg onto the frame's value stack */
result = arg ? arg : Py_None;
Py_INCREF(result);
*(f->f_stacktop++) = result;
}
/* Generators always return to their most recent caller, not
* necessarily their creator. */
Py_XINCREF(tstate->frame);
assert(f->f_back == NULL);
f->f_back = tstate->frame; // 关键
gen->gi_running = 1;
gen->gi_exc_state.previous_item = tstate->exc_info;
tstate->exc_info = &gen->gi_exc_state;
result = PyEval_EvalFrameEx(f, exc); // 关键
tstate->exc_info = gen->gi_exc_state.previous_item;
gen->gi_exc_state.previous_item = NULL;
gen->gi_running = 0;
/* Don't keep the reference to f_back any longer than necessary. It
* may keep a chain of frames alive or it could create a reference
* cycle. */
assert(f->f_back == tstate->frame);
Py_CLEAR(f->f_back);
/* If the generator just returned (as opposed to yielding), signal
* that the generator is exhausted. */
if (result && f->f_stacktop == NULL) {
if (result == Py_None) {
/* Delay exception instantiation if we can */
if (PyAsyncGen_CheckExact(gen)) {
PyErr_SetNone(PyExc_StopAsyncIteration);
}
else {
PyErr_SetNone(PyExc_StopIteration);
}
}
else {
/* Async generators cannot return anything but None */
assert(!PyAsyncGen_CheckExact(gen));
_PyGen_SetStopIterationValue(result);
}
Py_CLEAR(result);
}
else if (!result && PyErr_ExceptionMatches(PyExc_StopIteration)) {
const char *msg = "generator raised StopIteration";
if (PyCoro_CheckExact(gen)) {
msg = "coroutine raised StopIteration";
}
else if PyAsyncGen_CheckExact(gen) {
msg = "async generator raised StopIteration";
}
_PyErr_FormatFromCause(PyExc_RuntimeError, "%s", msg);
}
else if (!result && PyAsyncGen_CheckExact(gen) &&
PyErr_ExceptionMatches(PyExc_StopAsyncIteration))
{
/* code in `gen` raised a StopAsyncIteration error:
raise a RuntimeError.
*/
const char *msg = "async generator raised StopAsyncIteration";
_PyErr_FormatFromCause(PyExc_RuntimeError, "%s", msg);
}
if (!result || f->f_stacktop == NULL) {
/* generator can't be rerun, so release the frame */
/* first clean reference cycle through stored exception traceback */
exc_state_clear(&gen->gi_exc_state);
gen->gi_frame->f_gen = NULL;
gen->gi_frame = NULL;
Py_DECREF(f);
}
return result;
}
# YIELD_VALUE
TARGET(YIELD_VALUE) {
retval = POP();
if (co->co_flags & CO_ASYNC_GENERATOR) {
PyObject *w = _PyAsyncGenValueWrapperNew(retval);
Py_DECREF(retval);
if (w == NULL) {
retval = NULL;
goto error;
}
retval = w;
}
f->f_stacktop = stack_pointer;
why = WHY_YIELD;
goto fast_yield;