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cpython/Objects/genobject.c

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/* Generator object implementation */
#include "Python.h"
#include "frameobject.h"
#include "structmember.h"
#include "opcode.h"
static PyObject *gen_close(PyGenObject *gen, PyObject *args);
static int
gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
{
Py_VISIT((PyObject *)gen->gi_frame);
Py_VISIT(gen->gi_code);
Py_VISIT(gen->gi_name);
Py_VISIT(gen->gi_qualname);
return 0;
}
void
_PyGen_Finalize(PyObject *self)
{
PyGenObject *gen = (PyGenObject *)self;
PyObject *res;
PyObject *error_type, *error_value, *error_traceback;
/* If `gen` is a coroutine, and if it was never awaited on,
issue a RuntimeWarning. */
if (gen->gi_code != NULL
&& ((PyCodeObject *)gen->gi_code)->co_flags & (CO_COROUTINE
| CO_ITERABLE_COROUTINE)
&& gen->gi_frame != NULL
&& gen->gi_frame->f_lasti == -1
&& !PyErr_Occurred()
&& PyErr_WarnFormat(PyExc_RuntimeWarning, 1,
"coroutine '%.50S' was never awaited",
gen->gi_qualname))
return;
if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
/* Generator isn't paused, so no need to close */
return;
/* Save the current exception, if any. */
PyErr_Fetch(&error_type, &error_value, &error_traceback);
res = gen_close(gen, NULL);
if (res == NULL)
PyErr_WriteUnraisable(self);
else
Py_DECREF(res);
/* Restore the saved exception. */
PyErr_Restore(error_type, error_value, error_traceback);
}
static void
gen_dealloc(PyGenObject *gen)
{
PyObject *self = (PyObject *) gen;
_PyObject_GC_UNTRACK(gen);
if (gen->gi_weakreflist != NULL)
PyObject_ClearWeakRefs(self);
_PyObject_GC_TRACK(self);
if (PyObject_CallFinalizerFromDealloc(self))
return; /* resurrected. :( */
_PyObject_GC_UNTRACK(self);
Py_CLEAR(gen->gi_frame);
Py_CLEAR(gen->gi_code);
Py_CLEAR(gen->gi_name);
Py_CLEAR(gen->gi_qualname);
PyObject_GC_Del(gen);
}
static PyObject *
gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
{
PyThreadState *tstate = PyThreadState_GET();
PyFrameObject *f = gen->gi_frame;
PyObject *result;
if (gen->gi_running) {
PyErr_SetString(PyExc_ValueError,
"generator already executing");
return NULL;
}
if (f == NULL || f->f_stacktop == NULL) {
/* Only set exception if called from send() */
if (arg && !exc)
PyErr_SetNone(PyExc_StopIteration);
return NULL;
}
if (f->f_lasti == -1) {
if (arg && arg != Py_None) {
PyErr_SetString(PyExc_TypeError,
"can't send non-None value to a "
"just-started generator");
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;
gen->gi_running = 1;
result = PyEval_EvalFrameEx(f, exc);
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 */
PyErr_SetNone(PyExc_StopIteration);
} else {
PyObject *e = PyObject_CallFunctionObjArgs(
PyExc_StopIteration, result, NULL);
if (e != NULL) {
PyErr_SetObject(PyExc_StopIteration, e);
Py_DECREF(e);
}
}
Py_CLEAR(result);
}
else if (!result) {
/* Check for __future__ generator_stop and conditionally turn
* a leaking StopIteration into RuntimeError (with its cause
* set appropriately). */
if ((((PyCodeObject *)gen->gi_code)->co_flags &
(CO_FUTURE_GENERATOR_STOP | CO_COROUTINE | CO_ITERABLE_COROUTINE))
&& PyErr_ExceptionMatches(PyExc_StopIteration))
{
PyObject *exc, *val, *val2, *tb;
PyErr_Fetch(&exc, &val, &tb);
PyErr_NormalizeException(&exc, &val, &tb);
if (tb != NULL)
PyException_SetTraceback(val, tb);
Py_DECREF(exc);
Py_XDECREF(tb);
PyErr_SetString(PyExc_RuntimeError,
"generator raised StopIteration");
PyErr_Fetch(&exc, &val2, &tb);
PyErr_NormalizeException(&exc, &val2, &tb);
Py_INCREF(val);
PyException_SetCause(val2, val);
PyException_SetContext(val2, val);
PyErr_Restore(exc, val2, tb);
}
}
if (!result || f->f_stacktop == NULL) {
/* generator can't be rerun, so release the frame */
/* first clean reference cycle through stored exception traceback */
PyObject *t, *v, *tb;
t = f->f_exc_type;
v = f->f_exc_value;
tb = f->f_exc_traceback;
f->f_exc_type = NULL;
f->f_exc_value = NULL;
f->f_exc_traceback = NULL;
Py_XDECREF(t);
Py_XDECREF(v);
Py_XDECREF(tb);
gen->gi_frame->f_gen = NULL;
gen->gi_frame = NULL;
Py_DECREF(f);
}
return result;
}
PyDoc_STRVAR(send_doc,
"send(arg) -> send 'arg' into generator,\n\
return next yielded value or raise StopIteration.");
PyObject *
_PyGen_Send(PyGenObject *gen, PyObject *arg)
{
return gen_send_ex(gen, arg, 0);
}
PyDoc_STRVAR(close_doc,
"close() -> raise GeneratorExit inside generator.");
/*
* This helper function is used by gen_close and gen_throw to
* close a subiterator being delegated to by yield-from.
*/
static int
gen_close_iter(PyObject *yf)
{
PyObject *retval = NULL;
_Py_IDENTIFIER(close);
if (PyGen_CheckExact(yf)) {
retval = gen_close((PyGenObject *)yf, NULL);
if (retval == NULL)
return -1;
} else {
PyObject *meth = _PyObject_GetAttrId(yf, &PyId_close);
if (meth == NULL) {
if (!PyErr_ExceptionMatches(PyExc_AttributeError))
PyErr_WriteUnraisable(yf);
PyErr_Clear();
} else {
retval = PyObject_CallFunction(meth, "");
Py_DECREF(meth);
if (retval == NULL)
return -1;
}
}
Py_XDECREF(retval);
return 0;
}
static PyObject *
gen_yf(PyGenObject *gen)
{
PyObject *yf = NULL;
PyFrameObject *f = gen->gi_frame;
if (f && f->f_stacktop) {
PyObject *bytecode = f->f_code->co_code;
unsigned char *code = (unsigned char *)PyBytes_AS_STRING(bytecode);
if (code[f->f_lasti + 1] != YIELD_FROM)
return NULL;
yf = f->f_stacktop[-1];
Py_INCREF(yf);
}
return yf;
}
static PyObject *
gen_close(PyGenObject *gen, PyObject *args)
{
PyObject *retval;
PyObject *yf = gen_yf(gen);
int err = 0;
if (yf) {
gen->gi_running = 1;
err = gen_close_iter(yf);
gen->gi_running = 0;
Py_DECREF(yf);
}
if (err == 0)
PyErr_SetNone(PyExc_GeneratorExit);
retval = gen_send_ex(gen, Py_None, 1);
if (retval) {
Py_DECREF(retval);
PyErr_SetString(PyExc_RuntimeError,
"generator ignored GeneratorExit");
return NULL;
}
if (PyErr_ExceptionMatches(PyExc_StopIteration)
|| PyErr_ExceptionMatches(PyExc_GeneratorExit)) {
PyErr_Clear(); /* ignore these errors */
Py_INCREF(Py_None);
return Py_None;
}
return NULL;
}
PyDoc_STRVAR(throw_doc,
"throw(typ[,val[,tb]]) -> raise exception in generator,\n\
return next yielded value or raise StopIteration.");
static PyObject *
gen_throw(PyGenObject *gen, PyObject *args)
{
PyObject *typ;
PyObject *tb = NULL;
PyObject *val = NULL;
PyObject *yf = gen_yf(gen);
_Py_IDENTIFIER(throw);
if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb))
return NULL;
if (yf) {
PyObject *ret;
int err;
if (PyErr_GivenExceptionMatches(typ, PyExc_GeneratorExit)) {
gen->gi_running = 1;
err = gen_close_iter(yf);
gen->gi_running = 0;
Py_DECREF(yf);
if (err < 0)
return gen_send_ex(gen, Py_None, 1);
goto throw_here;
}
if (PyGen_CheckExact(yf)) {
gen->gi_running = 1;
ret = gen_throw((PyGenObject *)yf, args);
gen->gi_running = 0;
} else {
PyObject *meth = _PyObject_GetAttrId(yf, &PyId_throw);
if (meth == NULL) {
if (!PyErr_ExceptionMatches(PyExc_AttributeError)) {
Py_DECREF(yf);
return NULL;
}
PyErr_Clear();
Py_DECREF(yf);
goto throw_here;
}
gen->gi_running = 1;
ret = PyObject_CallObject(meth, args);
gen->gi_running = 0;
Py_DECREF(meth);
}
Py_DECREF(yf);
if (!ret) {
PyObject *val;
/* Pop subiterator from stack */
ret = *(--gen->gi_frame->f_stacktop);
assert(ret == yf);
Py_DECREF(ret);
/* Termination repetition of YIELD_FROM */
gen->gi_frame->f_lasti++;
if (_PyGen_FetchStopIterationValue(&val) == 0) {
ret = gen_send_ex(gen, val, 0);
Py_DECREF(val);
} else {
ret = gen_send_ex(gen, Py_None, 1);
}
}
return ret;
}
throw_here:
/* First, check the traceback argument, replacing None with
NULL. */
if (tb == Py_None) {
tb = NULL;
}
else if (tb != NULL && !PyTraceBack_Check(tb)) {
PyErr_SetString(PyExc_TypeError,
"throw() third argument must be a traceback object");
return NULL;
}
Py_INCREF(typ);
Py_XINCREF(val);
Py_XINCREF(tb);
if (PyExceptionClass_Check(typ))
PyErr_NormalizeException(&typ, &val, &tb);
else if (PyExceptionInstance_Check(typ)) {
/* Raising an instance. The value should be a dummy. */
if (val && val != Py_None) {
PyErr_SetString(PyExc_TypeError,
"instance exception may not have a separate value");
goto failed_throw;
}
else {
/* Normalize to raise <class>, <instance> */
Py_XDECREF(val);
val = typ;
typ = PyExceptionInstance_Class(typ);
Py_INCREF(typ);
if (tb == NULL)
/* Returns NULL if there's no traceback */
tb = PyException_GetTraceback(val);
}
}
else {
/* Not something you can raise. throw() fails. */
PyErr_Format(PyExc_TypeError,
"exceptions must be classes or instances "
"deriving from BaseException, not %s",
Py_TYPE(typ)->tp_name);
goto failed_throw;
}
PyErr_Restore(typ, val, tb);
return gen_send_ex(gen, Py_None, 1);
failed_throw:
/* Didn't use our arguments, so restore their original refcounts */
Py_DECREF(typ);
Py_XDECREF(val);
Py_XDECREF(tb);
return NULL;
}
static PyObject *
gen_iternext(PyGenObject *gen)
{
if (((PyCodeObject*)gen->gi_code)->co_flags & CO_COROUTINE) {
PyErr_SetString(PyExc_TypeError,
"coroutine-objects do not support iteration");
return NULL;
}
return gen_send_ex(gen, NULL, 0);
}
/*
* If StopIteration exception is set, fetches its 'value'
* attribute if any, otherwise sets pvalue to None.
*
* Returns 0 if no exception or StopIteration is set.
* If any other exception is set, returns -1 and leaves
* pvalue unchanged.
*/
int
_PyGen_FetchStopIterationValue(PyObject **pvalue) {
PyObject *et, *ev, *tb;
PyObject *value = NULL;
if (PyErr_ExceptionMatches(PyExc_StopIteration)) {
PyErr_Fetch(&et, &ev, &tb);
if (ev) {
/* exception will usually be normalised already */
if (Py_TYPE(ev) == (PyTypeObject *) et
|| PyObject_IsInstance(ev, PyExc_StopIteration)) {
value = ((PyStopIterationObject *)ev)->value;
Py_INCREF(value);
Py_DECREF(ev);
} else if (et == PyExc_StopIteration) {
/* avoid normalisation and take ev as value */
value = ev;
} else {
/* normalisation required */
PyErr_NormalizeException(&et, &ev, &tb);
if (!PyObject_IsInstance(ev, PyExc_StopIteration)) {
PyErr_Restore(et, ev, tb);
return -1;
}
value = ((PyStopIterationObject *)ev)->value;
Py_INCREF(value);
Py_DECREF(ev);
}
}
Py_XDECREF(et);
Py_XDECREF(tb);
} else if (PyErr_Occurred()) {
return -1;
}
if (value == NULL) {
value = Py_None;
Py_INCREF(value);
}
*pvalue = value;
return 0;
}
static PyObject *
gen_repr(PyGenObject *gen)
{
if (PyGen_CheckCoroutineExact(gen)) {
return PyUnicode_FromFormat("<coroutine object %S at %p>",
gen->gi_qualname, gen);
}
else {
return PyUnicode_FromFormat("<generator object %S at %p>",
gen->gi_qualname, gen);
}
}
static PyObject *
gen_get_name(PyGenObject *op)
{
Py_INCREF(op->gi_name);
return op->gi_name;
}
static int
gen_set_name(PyGenObject *op, PyObject *value)
{
PyObject *tmp;
/* Not legal to del gen.gi_name or to set it to anything
* other than a string object. */
if (value == NULL || !PyUnicode_Check(value)) {
PyErr_SetString(PyExc_TypeError,
"__name__ must be set to a string object");
return -1;
}
tmp = op->gi_name;
Py_INCREF(value);
op->gi_name = value;
Py_DECREF(tmp);
return 0;
}
static PyObject *
gen_get_qualname(PyGenObject *op)
{
Py_INCREF(op->gi_qualname);
return op->gi_qualname;
}
static PyObject *
gen_get_iter(PyGenObject *gen)
{
if (((PyCodeObject*)gen->gi_code)->co_flags & CO_COROUTINE) {
PyErr_SetString(PyExc_TypeError,
"coroutine-objects do not support iteration");
return NULL;
}
Py_INCREF(gen);
return (PyObject *)gen;
}
static int
gen_set_qualname(PyGenObject *op, PyObject *value)
{
PyObject *tmp;
/* Not legal to del gen.__qualname__ or to set it to anything
* other than a string object. */
if (value == NULL || !PyUnicode_Check(value)) {
PyErr_SetString(PyExc_TypeError,
"__qualname__ must be set to a string object");
return -1;
}
tmp = op->gi_qualname;
Py_INCREF(value);
op->gi_qualname = value;
Py_DECREF(tmp);
return 0;
}
static PyGetSetDef gen_getsetlist[] = {
{"__name__", (getter)gen_get_name, (setter)gen_set_name,
PyDoc_STR("name of the generator")},
{"__qualname__", (getter)gen_get_qualname, (setter)gen_set_qualname,
PyDoc_STR("qualified name of the generator")},
{NULL} /* Sentinel */
};
static PyMemberDef gen_memberlist[] = {
{"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), READONLY},
{"gi_running", T_BOOL, offsetof(PyGenObject, gi_running), READONLY},
{"gi_code", T_OBJECT, offsetof(PyGenObject, gi_code), READONLY},
{NULL} /* Sentinel */
};
static PyMethodDef gen_methods[] = {
{"send",(PyCFunction)_PyGen_Send, METH_O, send_doc},
{"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
{"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
{NULL, NULL} /* Sentinel */
};
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 */
(getiterfunc)gen_get_iter, /* 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 */
};
PyObject *
PyGen_NewWithQualName(PyFrameObject *f, PyObject *name, PyObject *qualname)
{
PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);
if (gen == NULL) {
Py_DECREF(f);
return NULL;
}
gen->gi_frame = f;
f->f_gen = (PyObject *) gen;
Py_INCREF(f->f_code);
gen->gi_code = (PyObject *)(f->f_code);
gen->gi_running = 0;
gen->gi_weakreflist = NULL;
if (name != NULL)
gen->gi_name = name;
else
gen->gi_name = ((PyCodeObject *)gen->gi_code)->co_name;
Py_INCREF(gen->gi_name);
if (qualname != NULL)
gen->gi_qualname = qualname;
else
gen->gi_qualname = gen->gi_name;
Py_INCREF(gen->gi_qualname);
_PyObject_GC_TRACK(gen);
return (PyObject *)gen;
}
PyObject *
PyGen_New(PyFrameObject *f)
{
return PyGen_NewWithQualName(f, NULL, NULL);
}
int
PyGen_NeedsFinalizing(PyGenObject *gen)
{
int i;
PyFrameObject *f = gen->gi_frame;
if (f == NULL || f->f_stacktop == NULL)
return 0; /* no frame or empty blockstack == no finalization */
/* Any block type besides a loop requires cleanup. */
for (i = 0; i < f->f_iblock; i++)
if (f->f_blockstack[i].b_type != SETUP_LOOP)
return 1;
/* No blocks except loops, it's safe to skip finalization. */
return 0;
}
/*
* This helper function returns an awaitable for `o`:
* - `o` if `o` is a coroutine-object;
* - `type(o)->tp_as_async->am_await(o)`
*
* Raises a TypeError if it's not possible to return
* an awaitable and returns NULL.
*/
PyObject *
_PyGen_GetAwaitableIter(PyObject *o)
{
getawaitablefunc getter = NULL;
PyTypeObject *ot;
if (PyGen_CheckCoroutineExact(o)) {
/* Fast path. It's a central function for 'await'. */
Py_INCREF(o);
return o;
}
ot = Py_TYPE(o);
if (ot->tp_as_async != NULL) {
getter = ot->tp_as_async->am_await;
}
if (getter != NULL) {
PyObject *res = (*getter)(o);
if (res != NULL) {
if (!PyIter_Check(res)) {
PyErr_Format(PyExc_TypeError,
"__await__() returned non-iterator "
"of type '%.100s'",
Py_TYPE(res)->tp_name);
Py_CLEAR(res);
}
else {
if (PyGen_CheckCoroutineExact(res)) {
/* __await__ must return an *iterator*, not
a coroutine or another awaitable (see PEP 492) */
PyErr_SetString(PyExc_TypeError,
"__await__() returned a coroutine");
Py_CLEAR(res);
}
}
}
return res;
}
PyErr_Format(PyExc_TypeError,
"object %.100s can't be used in 'await' expression",
ot->tp_name);
return NULL;
}
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