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      1 /* Generator object implementation */
      2 
      3 #include "Python.h"
      4 #include "internal/pystate.h"
      5 #include "frameobject.h"
      6 #include "structmember.h"
      7 #include "opcode.h"
      8 
      9 static PyObject *gen_close(PyGenObject *, PyObject *);
     10 static PyObject *async_gen_asend_new(PyAsyncGenObject *, PyObject *);
     11 static PyObject *async_gen_athrow_new(PyAsyncGenObject *, PyObject *);
     12 
     13 static char *NON_INIT_CORO_MSG = "can't send non-None value to a "
     14                                  "just-started coroutine";
     15 
     16 static char *ASYNC_GEN_IGNORED_EXIT_MSG =
     17                                  "async generator ignored GeneratorExit";
     18 
     19 static inline int
     20 exc_state_traverse(_PyErr_StackItem *exc_state, visitproc visit, void *arg)
     21 {
     22     Py_VISIT(exc_state->exc_type);
     23     Py_VISIT(exc_state->exc_value);
     24     Py_VISIT(exc_state->exc_traceback);
     25     return 0;
     26 }
     27 
     28 static int
     29 gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
     30 {
     31     Py_VISIT((PyObject *)gen->gi_frame);
     32     Py_VISIT(gen->gi_code);
     33     Py_VISIT(gen->gi_name);
     34     Py_VISIT(gen->gi_qualname);
     35     /* No need to visit cr_origin, because it's just tuples/str/int, so can't
     36        participate in a reference cycle. */
     37     return exc_state_traverse(&gen->gi_exc_state, visit, arg);
     38 }
     39 
     40 void
     41 _PyGen_Finalize(PyObject *self)
     42 {
     43     PyGenObject *gen = (PyGenObject *)self;
     44     PyObject *res = NULL;
     45     PyObject *error_type, *error_value, *error_traceback;
     46 
     47     if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL) {
     48         /* Generator isn't paused, so no need to close */
     49         return;
     50     }
     51 
     52     if (PyAsyncGen_CheckExact(self)) {
     53         PyAsyncGenObject *agen = (PyAsyncGenObject*)self;
     54         PyObject *finalizer = agen->ag_finalizer;
     55         if (finalizer && !agen->ag_closed) {
     56             /* Save the current exception, if any. */
     57             PyErr_Fetch(&error_type, &error_value, &error_traceback);
     58 
     59             res = PyObject_CallFunctionObjArgs(finalizer, self, NULL);
     60 
     61             if (res == NULL) {
     62                 PyErr_WriteUnraisable(self);
     63             } else {
     64                 Py_DECREF(res);
     65             }
     66             /* Restore the saved exception. */
     67             PyErr_Restore(error_type, error_value, error_traceback);
     68             return;
     69         }
     70     }
     71 
     72     /* Save the current exception, if any. */
     73     PyErr_Fetch(&error_type, &error_value, &error_traceback);
     74 
     75     /* If `gen` is a coroutine, and if it was never awaited on,
     76        issue a RuntimeWarning. */
     77     if (gen->gi_code != NULL &&
     78         ((PyCodeObject *)gen->gi_code)->co_flags & CO_COROUTINE &&
     79         gen->gi_frame->f_lasti == -1)
     80     {
     81         _PyErr_WarnUnawaitedCoroutine((PyObject *)gen);
     82     }
     83     else {
     84         res = gen_close(gen, NULL);
     85     }
     86 
     87     if (res == NULL) {
     88         if (PyErr_Occurred()) {
     89             PyErr_WriteUnraisable(self);
     90         }
     91     }
     92     else {
     93         Py_DECREF(res);
     94     }
     95 
     96     /* Restore the saved exception. */
     97     PyErr_Restore(error_type, error_value, error_traceback);
     98 }
     99 
    100 static inline void
    101 exc_state_clear(_PyErr_StackItem *exc_state)
    102 {
    103     PyObject *t, *v, *tb;
    104     t = exc_state->exc_type;
    105     v = exc_state->exc_value;
    106     tb = exc_state->exc_traceback;
    107     exc_state->exc_type = NULL;
    108     exc_state->exc_value = NULL;
    109     exc_state->exc_traceback = NULL;
    110     Py_XDECREF(t);
    111     Py_XDECREF(v);
    112     Py_XDECREF(tb);
    113 }
    114 
    115 static void
    116 gen_dealloc(PyGenObject *gen)
    117 {
    118     PyObject *self = (PyObject *) gen;
    119 
    120     _PyObject_GC_UNTRACK(gen);
    121 
    122     if (gen->gi_weakreflist != NULL)
    123         PyObject_ClearWeakRefs(self);
    124 
    125     _PyObject_GC_TRACK(self);
    126 
    127     if (PyObject_CallFinalizerFromDealloc(self))
    128         return;                     /* resurrected.  :( */
    129 
    130     _PyObject_GC_UNTRACK(self);
    131     if (PyAsyncGen_CheckExact(gen)) {
    132         /* We have to handle this case for asynchronous generators
    133            right here, because this code has to be between UNTRACK
    134            and GC_Del. */
    135         Py_CLEAR(((PyAsyncGenObject*)gen)->ag_finalizer);
    136     }
    137     if (gen->gi_frame != NULL) {
    138         gen->gi_frame->f_gen = NULL;
    139         Py_CLEAR(gen->gi_frame);
    140     }
    141     if (((PyCodeObject *)gen->gi_code)->co_flags & CO_COROUTINE) {
    142         Py_CLEAR(((PyCoroObject *)gen)->cr_origin);
    143     }
    144     Py_CLEAR(gen->gi_code);
    145     Py_CLEAR(gen->gi_name);
    146     Py_CLEAR(gen->gi_qualname);
    147     exc_state_clear(&gen->gi_exc_state);
    148     PyObject_GC_Del(gen);
    149 }
    150 
    151 static PyObject *
    152 gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
    153 {
    154     PyThreadState *tstate = PyThreadState_GET();
    155     PyFrameObject *f = gen->gi_frame;
    156     PyObject *result;
    157 
    158     if (gen->gi_running) {
    159         const char *msg = "generator already executing";
    160         if (PyCoro_CheckExact(gen)) {
    161             msg = "coroutine already executing";
    162         }
    163         else if (PyAsyncGen_CheckExact(gen)) {
    164             msg = "async generator already executing";
    165         }
    166         PyErr_SetString(PyExc_ValueError, msg);
    167         return NULL;
    168     }
    169     if (f == NULL || f->f_stacktop == NULL) {
    170         if (PyCoro_CheckExact(gen) && !closing) {
    171             /* `gen` is an exhausted coroutine: raise an error,
    172                except when called from gen_close(), which should
    173                always be a silent method. */
    174             PyErr_SetString(
    175                 PyExc_RuntimeError,
    176                 "cannot reuse already awaited coroutine");
    177         }
    178         else if (arg && !exc) {
    179             /* `gen` is an exhausted generator:
    180                only set exception if called from send(). */
    181             if (PyAsyncGen_CheckExact(gen)) {
    182                 PyErr_SetNone(PyExc_StopAsyncIteration);
    183             }
    184             else {
    185                 PyErr_SetNone(PyExc_StopIteration);
    186             }
    187         }
    188         return NULL;
    189     }
    190 
    191     if (f->f_lasti == -1) {
    192         if (arg && arg != Py_None) {
    193             const char *msg = "can't send non-None value to a "
    194                               "just-started generator";
    195             if (PyCoro_CheckExact(gen)) {
    196                 msg = NON_INIT_CORO_MSG;
    197             }
    198             else if (PyAsyncGen_CheckExact(gen)) {
    199                 msg = "can't send non-None value to a "
    200                       "just-started async generator";
    201             }
    202             PyErr_SetString(PyExc_TypeError, msg);
    203             return NULL;
    204         }
    205     } else {
    206         /* Push arg onto the frame's value stack */
    207         result = arg ? arg : Py_None;
    208         Py_INCREF(result);
    209         *(f->f_stacktop++) = result;
    210     }
    211 
    212     /* Generators always return to their most recent caller, not
    213      * necessarily their creator. */
    214     Py_XINCREF(tstate->frame);
    215     assert(f->f_back == NULL);
    216     f->f_back = tstate->frame;
    217 
    218     gen->gi_running = 1;
    219     gen->gi_exc_state.previous_item = tstate->exc_info;
    220     tstate->exc_info = &gen->gi_exc_state;
    221     result = PyEval_EvalFrameEx(f, exc);
    222     tstate->exc_info = gen->gi_exc_state.previous_item;
    223     gen->gi_exc_state.previous_item = NULL;
    224     gen->gi_running = 0;
    225 
    226     /* Don't keep the reference to f_back any longer than necessary.  It
    227      * may keep a chain of frames alive or it could create a reference
    228      * cycle. */
    229     assert(f->f_back == tstate->frame);
    230     Py_CLEAR(f->f_back);
    231 
    232     /* If the generator just returned (as opposed to yielding), signal
    233      * that the generator is exhausted. */
    234     if (result && f->f_stacktop == NULL) {
    235         if (result == Py_None) {
    236             /* Delay exception instantiation if we can */
    237             if (PyAsyncGen_CheckExact(gen)) {
    238                 PyErr_SetNone(PyExc_StopAsyncIteration);
    239             }
    240             else {
    241                 PyErr_SetNone(PyExc_StopIteration);
    242             }
    243         }
    244         else {
    245             /* Async generators cannot return anything but None */
    246             assert(!PyAsyncGen_CheckExact(gen));
    247             _PyGen_SetStopIterationValue(result);
    248         }
    249         Py_CLEAR(result);
    250     }
    251     else if (!result && PyErr_ExceptionMatches(PyExc_StopIteration)) {
    252         const char *msg = "generator raised StopIteration";
    253         if (PyCoro_CheckExact(gen)) {
    254             msg = "coroutine raised StopIteration";
    255         }
    256         else if PyAsyncGen_CheckExact(gen) {
    257             msg = "async generator raised StopIteration";
    258         }
    259         _PyErr_FormatFromCause(PyExc_RuntimeError, "%s", msg);
    260 
    261     }
    262     else if (!result && PyAsyncGen_CheckExact(gen) &&
    263              PyErr_ExceptionMatches(PyExc_StopAsyncIteration))
    264     {
    265         /* code in `gen` raised a StopAsyncIteration error:
    266            raise a RuntimeError.
    267         */
    268         const char *msg = "async generator raised StopAsyncIteration";
    269         _PyErr_FormatFromCause(PyExc_RuntimeError, "%s", msg);
    270     }
    271 
    272     if (!result || f->f_stacktop == NULL) {
    273         /* generator can't be rerun, so release the frame */
    274         /* first clean reference cycle through stored exception traceback */
    275         exc_state_clear(&gen->gi_exc_state);
    276         gen->gi_frame->f_gen = NULL;
    277         gen->gi_frame = NULL;
    278         Py_DECREF(f);
    279     }
    280 
    281     return result;
    282 }
    283 
    284 PyDoc_STRVAR(send_doc,
    285 "send(arg) -> send 'arg' into generator,\n\
    286 return next yielded value or raise StopIteration.");
    287 
    288 PyObject *
    289 _PyGen_Send(PyGenObject *gen, PyObject *arg)
    290 {
    291     return gen_send_ex(gen, arg, 0, 0);
    292 }
    293 
    294 PyDoc_STRVAR(close_doc,
    295 "close() -> raise GeneratorExit inside generator.");
    296 
    297 /*
    298  *   This helper function is used by gen_close and gen_throw to
    299  *   close a subiterator being delegated to by yield-from.
    300  */
    301 
    302 static int
    303 gen_close_iter(PyObject *yf)
    304 {
    305     PyObject *retval = NULL;
    306     _Py_IDENTIFIER(close);
    307 
    308     if (PyGen_CheckExact(yf) || PyCoro_CheckExact(yf)) {
    309         retval = gen_close((PyGenObject *)yf, NULL);
    310         if (retval == NULL)
    311             return -1;
    312     }
    313     else {
    314         PyObject *meth;
    315         if (_PyObject_LookupAttrId(yf, &PyId_close, &meth) < 0) {
    316             PyErr_WriteUnraisable(yf);
    317         }
    318         if (meth) {
    319             retval = _PyObject_CallNoArg(meth);
    320             Py_DECREF(meth);
    321             if (retval == NULL)
    322                 return -1;
    323         }
    324     }
    325     Py_XDECREF(retval);
    326     return 0;
    327 }
    328 
    329 PyObject *
    330 _PyGen_yf(PyGenObject *gen)
    331 {
    332     PyObject *yf = NULL;
    333     PyFrameObject *f = gen->gi_frame;
    334 
    335     if (f && f->f_stacktop) {
    336         PyObject *bytecode = f->f_code->co_code;
    337         unsigned char *code = (unsigned char *)PyBytes_AS_STRING(bytecode);
    338 
    339         if (f->f_lasti < 0) {
    340             /* Return immediately if the frame didn't start yet. YIELD_FROM
    341                always come after LOAD_CONST: a code object should not start
    342                with YIELD_FROM */
    343             assert(code[0] != YIELD_FROM);
    344             return NULL;
    345         }
    346 
    347         if (code[f->f_lasti + sizeof(_Py_CODEUNIT)] != YIELD_FROM)
    348             return NULL;
    349         yf = f->f_stacktop[-1];
    350         Py_INCREF(yf);
    351     }
    352 
    353     return yf;
    354 }
    355 
    356 static PyObject *
    357 gen_close(PyGenObject *gen, PyObject *args)
    358 {
    359     PyObject *retval;
    360     PyObject *yf = _PyGen_yf(gen);
    361     int err = 0;
    362 
    363     if (yf) {
    364         gen->gi_running = 1;
    365         err = gen_close_iter(yf);
    366         gen->gi_running = 0;
    367         Py_DECREF(yf);
    368     }
    369     if (err == 0)
    370         PyErr_SetNone(PyExc_GeneratorExit);
    371     retval = gen_send_ex(gen, Py_None, 1, 1);
    372     if (retval) {
    373         const char *msg = "generator ignored GeneratorExit";
    374         if (PyCoro_CheckExact(gen)) {
    375             msg = "coroutine ignored GeneratorExit";
    376         } else if (PyAsyncGen_CheckExact(gen)) {
    377             msg = ASYNC_GEN_IGNORED_EXIT_MSG;
    378         }
    379         Py_DECREF(retval);
    380         PyErr_SetString(PyExc_RuntimeError, msg);
    381         return NULL;
    382     }
    383     if (PyErr_ExceptionMatches(PyExc_StopIteration)
    384         || PyErr_ExceptionMatches(PyExc_GeneratorExit)) {
    385         PyErr_Clear();          /* ignore these errors */
    386         Py_RETURN_NONE;
    387     }
    388     return NULL;
    389 }
    390 
    391 
    392 PyDoc_STRVAR(throw_doc,
    393 "throw(typ[,val[,tb]]) -> raise exception in generator,\n\
    394 return next yielded value or raise StopIteration.");
    395 
    396 static PyObject *
    397 _gen_throw(PyGenObject *gen, int close_on_genexit,
    398            PyObject *typ, PyObject *val, PyObject *tb)
    399 {
    400     PyObject *yf = _PyGen_yf(gen);
    401     _Py_IDENTIFIER(throw);
    402 
    403     if (yf) {
    404         PyObject *ret;
    405         int err;
    406         if (PyErr_GivenExceptionMatches(typ, PyExc_GeneratorExit) &&
    407             close_on_genexit
    408         ) {
    409             /* Asynchronous generators *should not* be closed right away.
    410                We have to allow some awaits to work it through, hence the
    411                `close_on_genexit` parameter here.
    412             */
    413             gen->gi_running = 1;
    414             err = gen_close_iter(yf);
    415             gen->gi_running = 0;
    416             Py_DECREF(yf);
    417             if (err < 0)
    418                 return gen_send_ex(gen, Py_None, 1, 0);
    419             goto throw_here;
    420         }
    421         if (PyGen_CheckExact(yf) || PyCoro_CheckExact(yf)) {
    422             /* `yf` is a generator or a coroutine. */
    423             gen->gi_running = 1;
    424             /* Close the generator that we are currently iterating with
    425                'yield from' or awaiting on with 'await'. */
    426             ret = _gen_throw((PyGenObject *)yf, close_on_genexit,
    427                              typ, val, tb);
    428             gen->gi_running = 0;
    429         } else {
    430             /* `yf` is an iterator or a coroutine-like object. */
    431             PyObject *meth;
    432             if (_PyObject_LookupAttrId(yf, &PyId_throw, &meth) < 0) {
    433                 Py_DECREF(yf);
    434                 return NULL;
    435             }
    436             if (meth == NULL) {
    437                 Py_DECREF(yf);
    438                 goto throw_here;
    439             }
    440             gen->gi_running = 1;
    441             ret = PyObject_CallFunctionObjArgs(meth, typ, val, tb, NULL);
    442             gen->gi_running = 0;
    443             Py_DECREF(meth);
    444         }
    445         Py_DECREF(yf);
    446         if (!ret) {
    447             PyObject *val;
    448             /* Pop subiterator from stack */
    449             ret = *(--gen->gi_frame->f_stacktop);
    450             assert(ret == yf);
    451             Py_DECREF(ret);
    452             /* Termination repetition of YIELD_FROM */
    453             assert(gen->gi_frame->f_lasti >= 0);
    454             gen->gi_frame->f_lasti += sizeof(_Py_CODEUNIT);
    455             if (_PyGen_FetchStopIterationValue(&val) == 0) {
    456                 ret = gen_send_ex(gen, val, 0, 0);
    457                 Py_DECREF(val);
    458             } else {
    459                 ret = gen_send_ex(gen, Py_None, 1, 0);
    460             }
    461         }
    462         return ret;
    463     }
    464 
    465 throw_here:
    466     /* First, check the traceback argument, replacing None with
    467        NULL. */
    468     if (tb == Py_None) {
    469         tb = NULL;
    470     }
    471     else if (tb != NULL && !PyTraceBack_Check(tb)) {
    472         PyErr_SetString(PyExc_TypeError,
    473             "throw() third argument must be a traceback object");
    474         return NULL;
    475     }
    476 
    477     Py_INCREF(typ);
    478     Py_XINCREF(val);
    479     Py_XINCREF(tb);
    480 
    481     if (PyExceptionClass_Check(typ))
    482         PyErr_NormalizeException(&typ, &val, &tb);
    483 
    484     else if (PyExceptionInstance_Check(typ)) {
    485         /* Raising an instance.  The value should be a dummy. */
    486         if (val && val != Py_None) {
    487             PyErr_SetString(PyExc_TypeError,
    488               "instance exception may not have a separate value");
    489             goto failed_throw;
    490         }
    491         else {
    492             /* Normalize to raise <class>, <instance> */
    493             Py_XDECREF(val);
    494             val = typ;
    495             typ = PyExceptionInstance_Class(typ);
    496             Py_INCREF(typ);
    497 
    498             if (tb == NULL)
    499                 /* Returns NULL if there's no traceback */
    500                 tb = PyException_GetTraceback(val);
    501         }
    502     }
    503     else {
    504         /* Not something you can raise.  throw() fails. */
    505         PyErr_Format(PyExc_TypeError,
    506                      "exceptions must be classes or instances "
    507                      "deriving from BaseException, not %s",
    508                      Py_TYPE(typ)->tp_name);
    509             goto failed_throw;
    510     }
    511 
    512     PyErr_Restore(typ, val, tb);
    513     return gen_send_ex(gen, Py_None, 1, 0);
    514 
    515 failed_throw:
    516     /* Didn't use our arguments, so restore their original refcounts */
    517     Py_DECREF(typ);
    518     Py_XDECREF(val);
    519     Py_XDECREF(tb);
    520     return NULL;
    521 }
    522 
    523 
    524 static PyObject *
    525 gen_throw(PyGenObject *gen, PyObject *args)
    526 {
    527     PyObject *typ;
    528     PyObject *tb = NULL;
    529     PyObject *val = NULL;
    530 
    531     if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb)) {
    532         return NULL;
    533     }
    534 
    535     return _gen_throw(gen, 1, typ, val, tb);
    536 }
    537 
    538 
    539 static PyObject *
    540 gen_iternext(PyGenObject *gen)
    541 {
    542     return gen_send_ex(gen, NULL, 0, 0);
    543 }
    544 
    545 /*
    546  * Set StopIteration with specified value.  Value can be arbitrary object
    547  * or NULL.
    548  *
    549  * Returns 0 if StopIteration is set and -1 if any other exception is set.
    550  */
    551 int
    552 _PyGen_SetStopIterationValue(PyObject *value)
    553 {
    554     PyObject *e;
    555 
    556     if (value == NULL ||
    557         (!PyTuple_Check(value) && !PyExceptionInstance_Check(value)))
    558     {
    559         /* Delay exception instantiation if we can */
    560         PyErr_SetObject(PyExc_StopIteration, value);
    561         return 0;
    562     }
    563     /* Construct an exception instance manually with
    564      * PyObject_CallFunctionObjArgs and pass it to PyErr_SetObject.
    565      *
    566      * We do this to handle a situation when "value" is a tuple, in which
    567      * case PyErr_SetObject would set the value of StopIteration to
    568      * the first element of the tuple.
    569      *
    570      * (See PyErr_SetObject/_PyErr_CreateException code for details.)
    571      */
    572     e = PyObject_CallFunctionObjArgs(PyExc_StopIteration, value, NULL);
    573     if (e == NULL) {
    574         return -1;
    575     }
    576     PyErr_SetObject(PyExc_StopIteration, e);
    577     Py_DECREF(e);
    578     return 0;
    579 }
    580 
    581 /*
    582  *   If StopIteration exception is set, fetches its 'value'
    583  *   attribute if any, otherwise sets pvalue to None.
    584  *
    585  *   Returns 0 if no exception or StopIteration is set.
    586  *   If any other exception is set, returns -1 and leaves
    587  *   pvalue unchanged.
    588  */
    589 
    590 int
    591 _PyGen_FetchStopIterationValue(PyObject **pvalue)
    592 {
    593     PyObject *et, *ev, *tb;
    594     PyObject *value = NULL;
    595 
    596     if (PyErr_ExceptionMatches(PyExc_StopIteration)) {
    597         PyErr_Fetch(&et, &ev, &tb);
    598         if (ev) {
    599             /* exception will usually be normalised already */
    600             if (PyObject_TypeCheck(ev, (PyTypeObject *) et)) {
    601                 value = ((PyStopIterationObject *)ev)->value;
    602                 Py_INCREF(value);
    603                 Py_DECREF(ev);
    604             } else if (et == PyExc_StopIteration && !PyTuple_Check(ev)) {
    605                 /* Avoid normalisation and take ev as value.
    606                  *
    607                  * Normalization is required if the value is a tuple, in
    608                  * that case the value of StopIteration would be set to
    609                  * the first element of the tuple.
    610                  *
    611                  * (See _PyErr_CreateException code for details.)
    612                  */
    613                 value = ev;
    614             } else {
    615                 /* normalisation required */
    616                 PyErr_NormalizeException(&et, &ev, &tb);
    617                 if (!PyObject_TypeCheck(ev, (PyTypeObject *)PyExc_StopIteration)) {
    618                     PyErr_Restore(et, ev, tb);
    619                     return -1;
    620                 }
    621                 value = ((PyStopIterationObject *)ev)->value;
    622                 Py_INCREF(value);
    623                 Py_DECREF(ev);
    624             }
    625         }
    626         Py_XDECREF(et);
    627         Py_XDECREF(tb);
    628     } else if (PyErr_Occurred()) {
    629         return -1;
    630     }
    631     if (value == NULL) {
    632         value = Py_None;
    633         Py_INCREF(value);
    634     }
    635     *pvalue = value;
    636     return 0;
    637 }
    638 
    639 static PyObject *
    640 gen_repr(PyGenObject *gen)
    641 {
    642     return PyUnicode_FromFormat("<generator object %S at %p>",
    643                                 gen->gi_qualname, gen);
    644 }
    645 
    646 static PyObject *
    647 gen_get_name(PyGenObject *op, void *Py_UNUSED(ignored))
    648 {
    649     Py_INCREF(op->gi_name);
    650     return op->gi_name;
    651 }
    652 
    653 static int
    654 gen_set_name(PyGenObject *op, PyObject *value, void *Py_UNUSED(ignored))
    655 {
    656     /* Not legal to del gen.gi_name or to set it to anything
    657      * other than a string object. */
    658     if (value == NULL || !PyUnicode_Check(value)) {
    659         PyErr_SetString(PyExc_TypeError,
    660                         "__name__ must be set to a string object");
    661         return -1;
    662     }
    663     Py_INCREF(value);
    664     Py_XSETREF(op->gi_name, value);
    665     return 0;
    666 }
    667 
    668 static PyObject *
    669 gen_get_qualname(PyGenObject *op, void *Py_UNUSED(ignored))
    670 {
    671     Py_INCREF(op->gi_qualname);
    672     return op->gi_qualname;
    673 }
    674 
    675 static int
    676 gen_set_qualname(PyGenObject *op, PyObject *value, void *Py_UNUSED(ignored))
    677 {
    678     /* Not legal to del gen.__qualname__ or to set it to anything
    679      * other than a string object. */
    680     if (value == NULL || !PyUnicode_Check(value)) {
    681         PyErr_SetString(PyExc_TypeError,
    682                         "__qualname__ must be set to a string object");
    683         return -1;
    684     }
    685     Py_INCREF(value);
    686     Py_XSETREF(op->gi_qualname, value);
    687     return 0;
    688 }
    689 
    690 static PyObject *
    691 gen_getyieldfrom(PyGenObject *gen, void *Py_UNUSED(ignored))
    692 {
    693     PyObject *yf = _PyGen_yf(gen);
    694     if (yf == NULL)
    695         Py_RETURN_NONE;
    696     return yf;
    697 }
    698 
    699 static PyGetSetDef gen_getsetlist[] = {
    700     {"__name__", (getter)gen_get_name, (setter)gen_set_name,
    701      PyDoc_STR("name of the generator")},
    702     {"__qualname__", (getter)gen_get_qualname, (setter)gen_set_qualname,
    703      PyDoc_STR("qualified name of the generator")},
    704     {"gi_yieldfrom", (getter)gen_getyieldfrom, NULL,
    705      PyDoc_STR("object being iterated by yield from, or None")},
    706     {NULL} /* Sentinel */
    707 };
    708 
    709 static PyMemberDef gen_memberlist[] = {
    710     {"gi_frame",     T_OBJECT, offsetof(PyGenObject, gi_frame),    READONLY},
    711     {"gi_running",   T_BOOL,   offsetof(PyGenObject, gi_running),  READONLY},
    712     {"gi_code",      T_OBJECT, offsetof(PyGenObject, gi_code),     READONLY},
    713     {NULL}      /* Sentinel */
    714 };
    715 
    716 static PyMethodDef gen_methods[] = {
    717     {"send",(PyCFunction)_PyGen_Send, METH_O, send_doc},
    718     {"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
    719     {"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
    720     {NULL, NULL}        /* Sentinel */
    721 };
    722 
    723 PyTypeObject PyGen_Type = {
    724     PyVarObject_HEAD_INIT(&PyType_Type, 0)
    725     "generator",                                /* tp_name */
    726     sizeof(PyGenObject),                        /* tp_basicsize */
    727     0,                                          /* tp_itemsize */
    728     /* methods */
    729     (destructor)gen_dealloc,                    /* tp_dealloc */
    730     0,                                          /* tp_print */
    731     0,                                          /* tp_getattr */
    732     0,                                          /* tp_setattr */
    733     0,                                          /* tp_as_async */
    734     (reprfunc)gen_repr,                         /* tp_repr */
    735     0,                                          /* tp_as_number */
    736     0,                                          /* tp_as_sequence */
    737     0,                                          /* tp_as_mapping */
    738     0,                                          /* tp_hash */
    739     0,                                          /* tp_call */
    740     0,                                          /* tp_str */
    741     PyObject_GenericGetAttr,                    /* tp_getattro */
    742     0,                                          /* tp_setattro */
    743     0,                                          /* tp_as_buffer */
    744     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
    745         Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
    746     0,                                          /* tp_doc */
    747     (traverseproc)gen_traverse,                 /* tp_traverse */
    748     0,                                          /* tp_clear */
    749     0,                                          /* tp_richcompare */
    750     offsetof(PyGenObject, gi_weakreflist),      /* tp_weaklistoffset */
    751     PyObject_SelfIter,                          /* tp_iter */
    752     (iternextfunc)gen_iternext,                 /* tp_iternext */
    753     gen_methods,                                /* tp_methods */
    754     gen_memberlist,                             /* tp_members */
    755     gen_getsetlist,                             /* tp_getset */
    756     0,                                          /* tp_base */
    757     0,                                          /* tp_dict */
    758 
    759     0,                                          /* tp_descr_get */
    760     0,                                          /* tp_descr_set */
    761     0,                                          /* tp_dictoffset */
    762     0,                                          /* tp_init */
    763     0,                                          /* tp_alloc */
    764     0,                                          /* tp_new */
    765     0,                                          /* tp_free */
    766     0,                                          /* tp_is_gc */
    767     0,                                          /* tp_bases */
    768     0,                                          /* tp_mro */
    769     0,                                          /* tp_cache */
    770     0,                                          /* tp_subclasses */
    771     0,                                          /* tp_weaklist */
    772     0,                                          /* tp_del */
    773     0,                                          /* tp_version_tag */
    774     _PyGen_Finalize,                            /* tp_finalize */
    775 };
    776 
    777 static PyObject *
    778 gen_new_with_qualname(PyTypeObject *type, PyFrameObject *f,
    779                       PyObject *name, PyObject *qualname)
    780 {
    781     PyGenObject *gen = PyObject_GC_New(PyGenObject, type);
    782     if (gen == NULL) {
    783         Py_DECREF(f);
    784         return NULL;
    785     }
    786     gen->gi_frame = f;
    787     f->f_gen = (PyObject *) gen;
    788     Py_INCREF(f->f_code);
    789     gen->gi_code = (PyObject *)(f->f_code);
    790     gen->gi_running = 0;
    791     gen->gi_weakreflist = NULL;
    792     gen->gi_exc_state.exc_type = NULL;
    793     gen->gi_exc_state.exc_value = NULL;
    794     gen->gi_exc_state.exc_traceback = NULL;
    795     gen->gi_exc_state.previous_item = NULL;
    796     if (name != NULL)
    797         gen->gi_name = name;
    798     else
    799         gen->gi_name = ((PyCodeObject *)gen->gi_code)->co_name;
    800     Py_INCREF(gen->gi_name);
    801     if (qualname != NULL)
    802         gen->gi_qualname = qualname;
    803     else
    804         gen->gi_qualname = gen->gi_name;
    805     Py_INCREF(gen->gi_qualname);
    806     _PyObject_GC_TRACK(gen);
    807     return (PyObject *)gen;
    808 }
    809 
    810 PyObject *
    811 PyGen_NewWithQualName(PyFrameObject *f, PyObject *name, PyObject *qualname)
    812 {
    813     return gen_new_with_qualname(&PyGen_Type, f, name, qualname);
    814 }
    815 
    816 PyObject *
    817 PyGen_New(PyFrameObject *f)
    818 {
    819     return gen_new_with_qualname(&PyGen_Type, f, NULL, NULL);
    820 }
    821 
    822 int
    823 PyGen_NeedsFinalizing(PyGenObject *gen)
    824 {
    825     int i;
    826     PyFrameObject *f = gen->gi_frame;
    827 
    828     if (f == NULL || f->f_stacktop == NULL)
    829         return 0; /* no frame or empty blockstack == no finalization */
    830 
    831     /* Any block type besides a loop requires cleanup. */
    832     for (i = 0; i < f->f_iblock; i++)
    833         if (f->f_blockstack[i].b_type != SETUP_LOOP)
    834             return 1;
    835 
    836     /* No blocks except loops, it's safe to skip finalization. */
    837     return 0;
    838 }
    839 
    840 /* Coroutine Object */
    841 
    842 typedef struct {
    843     PyObject_HEAD
    844     PyCoroObject *cw_coroutine;
    845 } PyCoroWrapper;
    846 
    847 static int
    848 gen_is_coroutine(PyObject *o)
    849 {
    850     if (PyGen_CheckExact(o)) {
    851         PyCodeObject *code = (PyCodeObject *)((PyGenObject*)o)->gi_code;
    852         if (code->co_flags & CO_ITERABLE_COROUTINE) {
    853             return 1;
    854         }
    855     }
    856     return 0;
    857 }
    858 
    859 /*
    860  *   This helper function returns an awaitable for `o`:
    861  *     - `o` if `o` is a coroutine-object;
    862  *     - `type(o)->tp_as_async->am_await(o)`
    863  *
    864  *   Raises a TypeError if it's not possible to return
    865  *   an awaitable and returns NULL.
    866  */
    867 PyObject *
    868 _PyCoro_GetAwaitableIter(PyObject *o)
    869 {
    870     unaryfunc getter = NULL;
    871     PyTypeObject *ot;
    872 
    873     if (PyCoro_CheckExact(o) || gen_is_coroutine(o)) {
    874         /* 'o' is a coroutine. */
    875         Py_INCREF(o);
    876         return o;
    877     }
    878 
    879     ot = Py_TYPE(o);
    880     if (ot->tp_as_async != NULL) {
    881         getter = ot->tp_as_async->am_await;
    882     }
    883     if (getter != NULL) {
    884         PyObject *res = (*getter)(o);
    885         if (res != NULL) {
    886             if (PyCoro_CheckExact(res) || gen_is_coroutine(res)) {
    887                 /* __await__ must return an *iterator*, not
    888                    a coroutine or another awaitable (see PEP 492) */
    889                 PyErr_SetString(PyExc_TypeError,
    890                                 "__await__() returned a coroutine");
    891                 Py_CLEAR(res);
    892             } else if (!PyIter_Check(res)) {
    893                 PyErr_Format(PyExc_TypeError,
    894                              "__await__() returned non-iterator "
    895                              "of type '%.100s'",
    896                              Py_TYPE(res)->tp_name);
    897                 Py_CLEAR(res);
    898             }
    899         }
    900         return res;
    901     }
    902 
    903     PyErr_Format(PyExc_TypeError,
    904                  "object %.100s can't be used in 'await' expression",
    905                  ot->tp_name);
    906     return NULL;
    907 }
    908 
    909 static PyObject *
    910 coro_repr(PyCoroObject *coro)
    911 {
    912     return PyUnicode_FromFormat("<coroutine object %S at %p>",
    913                                 coro->cr_qualname, coro);
    914 }
    915 
    916 static PyObject *
    917 coro_await(PyCoroObject *coro)
    918 {
    919     PyCoroWrapper *cw = PyObject_GC_New(PyCoroWrapper, &_PyCoroWrapper_Type);
    920     if (cw == NULL) {
    921         return NULL;
    922     }
    923     Py_INCREF(coro);
    924     cw->cw_coroutine = coro;
    925     _PyObject_GC_TRACK(cw);
    926     return (PyObject *)cw;
    927 }
    928 
    929 static PyObject *
    930 coro_get_cr_await(PyCoroObject *coro, void *Py_UNUSED(ignored))
    931 {
    932     PyObject *yf = _PyGen_yf((PyGenObject *) coro);
    933     if (yf == NULL)
    934         Py_RETURN_NONE;
    935     return yf;
    936 }
    937 
    938 static PyGetSetDef coro_getsetlist[] = {
    939     {"__name__", (getter)gen_get_name, (setter)gen_set_name,
    940      PyDoc_STR("name of the coroutine")},
    941     {"__qualname__", (getter)gen_get_qualname, (setter)gen_set_qualname,
    942      PyDoc_STR("qualified name of the coroutine")},
    943     {"cr_await", (getter)coro_get_cr_await, NULL,
    944      PyDoc_STR("object being awaited on, or None")},
    945     {NULL} /* Sentinel */
    946 };
    947 
    948 static PyMemberDef coro_memberlist[] = {
    949     {"cr_frame",     T_OBJECT, offsetof(PyCoroObject, cr_frame),    READONLY},
    950     {"cr_running",   T_BOOL,   offsetof(PyCoroObject, cr_running),  READONLY},
    951     {"cr_code",      T_OBJECT, offsetof(PyCoroObject, cr_code),     READONLY},
    952     {"cr_origin",    T_OBJECT, offsetof(PyCoroObject, cr_origin),   READONLY},
    953     {NULL}      /* Sentinel */
    954 };
    955 
    956 PyDoc_STRVAR(coro_send_doc,
    957 "send(arg) -> send 'arg' into coroutine,\n\
    958 return next iterated value or raise StopIteration.");
    959 
    960 PyDoc_STRVAR(coro_throw_doc,
    961 "throw(typ[,val[,tb]]) -> raise exception in coroutine,\n\
    962 return next iterated value or raise StopIteration.");
    963 
    964 PyDoc_STRVAR(coro_close_doc,
    965 "close() -> raise GeneratorExit inside coroutine.");
    966 
    967 static PyMethodDef coro_methods[] = {
    968     {"send",(PyCFunction)_PyGen_Send, METH_O, coro_send_doc},
    969     {"throw",(PyCFunction)gen_throw, METH_VARARGS, coro_throw_doc},
    970     {"close",(PyCFunction)gen_close, METH_NOARGS, coro_close_doc},
    971     {NULL, NULL}        /* Sentinel */
    972 };
    973 
    974 static PyAsyncMethods coro_as_async = {
    975     (unaryfunc)coro_await,                      /* am_await */
    976     0,                                          /* am_aiter */
    977     0                                           /* am_anext */
    978 };
    979 
    980 PyTypeObject PyCoro_Type = {
    981     PyVarObject_HEAD_INIT(&PyType_Type, 0)
    982     "coroutine",                                /* tp_name */
    983     sizeof(PyCoroObject),                       /* tp_basicsize */
    984     0,                                          /* tp_itemsize */
    985     /* methods */
    986     (destructor)gen_dealloc,                    /* tp_dealloc */
    987     0,                                          /* tp_print */
    988     0,                                          /* tp_getattr */
    989     0,                                          /* tp_setattr */
    990     &coro_as_async,                             /* tp_as_async */
    991     (reprfunc)coro_repr,                        /* tp_repr */
    992     0,                                          /* tp_as_number */
    993     0,                                          /* tp_as_sequence */
    994     0,                                          /* tp_as_mapping */
    995     0,                                          /* tp_hash */
    996     0,                                          /* tp_call */
    997     0,                                          /* tp_str */
    998     PyObject_GenericGetAttr,                    /* tp_getattro */
    999     0,                                          /* tp_setattro */
   1000     0,                                          /* tp_as_buffer */
   1001     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
   1002         Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
   1003     0,                                          /* tp_doc */
   1004     (traverseproc)gen_traverse,                 /* tp_traverse */
   1005     0,                                          /* tp_clear */
   1006     0,                                          /* tp_richcompare */
   1007     offsetof(PyCoroObject, cr_weakreflist),     /* tp_weaklistoffset */
   1008     0,                                          /* tp_iter */
   1009     0,                                          /* tp_iternext */
   1010     coro_methods,                               /* tp_methods */
   1011     coro_memberlist,                            /* tp_members */
   1012     coro_getsetlist,                            /* tp_getset */
   1013     0,                                          /* tp_base */
   1014     0,                                          /* tp_dict */
   1015     0,                                          /* tp_descr_get */
   1016     0,                                          /* tp_descr_set */
   1017     0,                                          /* tp_dictoffset */
   1018     0,                                          /* tp_init */
   1019     0,                                          /* tp_alloc */
   1020     0,                                          /* tp_new */
   1021     0,                                          /* tp_free */
   1022     0,                                          /* tp_is_gc */
   1023     0,                                          /* tp_bases */
   1024     0,                                          /* tp_mro */
   1025     0,                                          /* tp_cache */
   1026     0,                                          /* tp_subclasses */
   1027     0,                                          /* tp_weaklist */
   1028     0,                                          /* tp_del */
   1029     0,                                          /* tp_version_tag */
   1030     _PyGen_Finalize,                            /* tp_finalize */
   1031 };
   1032 
   1033 static void
   1034 coro_wrapper_dealloc(PyCoroWrapper *cw)
   1035 {
   1036     _PyObject_GC_UNTRACK((PyObject *)cw);
   1037     Py_CLEAR(cw->cw_coroutine);
   1038     PyObject_GC_Del(cw);
   1039 }
   1040 
   1041 static PyObject *
   1042 coro_wrapper_iternext(PyCoroWrapper *cw)
   1043 {
   1044     return gen_send_ex((PyGenObject *)cw->cw_coroutine, NULL, 0, 0);
   1045 }
   1046 
   1047 static PyObject *
   1048 coro_wrapper_send(PyCoroWrapper *cw, PyObject *arg)
   1049 {
   1050     return gen_send_ex((PyGenObject *)cw->cw_coroutine, arg, 0, 0);
   1051 }
   1052 
   1053 static PyObject *
   1054 coro_wrapper_throw(PyCoroWrapper *cw, PyObject *args)
   1055 {
   1056     return gen_throw((PyGenObject *)cw->cw_coroutine, args);
   1057 }
   1058 
   1059 static PyObject *
   1060 coro_wrapper_close(PyCoroWrapper *cw, PyObject *args)
   1061 {
   1062     return gen_close((PyGenObject *)cw->cw_coroutine, args);
   1063 }
   1064 
   1065 static int
   1066 coro_wrapper_traverse(PyCoroWrapper *cw, visitproc visit, void *arg)
   1067 {
   1068     Py_VISIT((PyObject *)cw->cw_coroutine);
   1069     return 0;
   1070 }
   1071 
   1072 static PyMethodDef coro_wrapper_methods[] = {
   1073     {"send",(PyCFunction)coro_wrapper_send, METH_O, coro_send_doc},
   1074     {"throw",(PyCFunction)coro_wrapper_throw, METH_VARARGS, coro_throw_doc},
   1075     {"close",(PyCFunction)coro_wrapper_close, METH_NOARGS, coro_close_doc},
   1076     {NULL, NULL}        /* Sentinel */
   1077 };
   1078 
   1079 PyTypeObject _PyCoroWrapper_Type = {
   1080     PyVarObject_HEAD_INIT(&PyType_Type, 0)
   1081     "coroutine_wrapper",
   1082     sizeof(PyCoroWrapper),                      /* tp_basicsize */
   1083     0,                                          /* tp_itemsize */
   1084     (destructor)coro_wrapper_dealloc,           /* destructor tp_dealloc */
   1085     0,                                          /* tp_print */
   1086     0,                                          /* tp_getattr */
   1087     0,                                          /* tp_setattr */
   1088     0,                                          /* tp_as_async */
   1089     0,                                          /* tp_repr */
   1090     0,                                          /* tp_as_number */
   1091     0,                                          /* tp_as_sequence */
   1092     0,                                          /* tp_as_mapping */
   1093     0,                                          /* tp_hash */
   1094     0,                                          /* tp_call */
   1095     0,                                          /* tp_str */
   1096     PyObject_GenericGetAttr,                    /* tp_getattro */
   1097     0,                                          /* tp_setattro */
   1098     0,                                          /* tp_as_buffer */
   1099     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
   1100     "A wrapper object implementing __await__ for coroutines.",
   1101     (traverseproc)coro_wrapper_traverse,        /* tp_traverse */
   1102     0,                                          /* tp_clear */
   1103     0,                                          /* tp_richcompare */
   1104     0,                                          /* tp_weaklistoffset */
   1105     PyObject_SelfIter,                          /* tp_iter */
   1106     (iternextfunc)coro_wrapper_iternext,        /* tp_iternext */
   1107     coro_wrapper_methods,                       /* tp_methods */
   1108     0,                                          /* tp_members */
   1109     0,                                          /* tp_getset */
   1110     0,                                          /* tp_base */
   1111     0,                                          /* tp_dict */
   1112     0,                                          /* tp_descr_get */
   1113     0,                                          /* tp_descr_set */
   1114     0,                                          /* tp_dictoffset */
   1115     0,                                          /* tp_init */
   1116     0,                                          /* tp_alloc */
   1117     0,                                          /* tp_new */
   1118     0,                                          /* tp_free */
   1119 };
   1120 
   1121 static PyObject *
   1122 compute_cr_origin(int origin_depth)
   1123 {
   1124     PyFrameObject *frame = PyEval_GetFrame();
   1125     /* First count how many frames we have */
   1126     int frame_count = 0;
   1127     for (; frame && frame_count < origin_depth; ++frame_count) {
   1128         frame = frame->f_back;
   1129     }
   1130 
   1131     /* Now collect them */
   1132     PyObject *cr_origin = PyTuple_New(frame_count);
   1133     if (cr_origin == NULL) {
   1134         return NULL;
   1135     }
   1136     frame = PyEval_GetFrame();
   1137     for (int i = 0; i < frame_count; ++i) {
   1138         PyObject *frameinfo = Py_BuildValue(
   1139             "OiO",
   1140             frame->f_code->co_filename,
   1141             PyFrame_GetLineNumber(frame),
   1142             frame->f_code->co_name);
   1143         if (!frameinfo) {
   1144             Py_DECREF(cr_origin);
   1145             return NULL;
   1146         }
   1147         PyTuple_SET_ITEM(cr_origin, i, frameinfo);
   1148         frame = frame->f_back;
   1149     }
   1150 
   1151     return cr_origin;
   1152 }
   1153 
   1154 PyObject *
   1155 PyCoro_New(PyFrameObject *f, PyObject *name, PyObject *qualname)
   1156 {
   1157     PyObject *coro = gen_new_with_qualname(&PyCoro_Type, f, name, qualname);
   1158     if (!coro) {
   1159         return NULL;
   1160     }
   1161 
   1162     PyThreadState *tstate = PyThreadState_GET();
   1163     int origin_depth = tstate->coroutine_origin_tracking_depth;
   1164 
   1165     if (origin_depth == 0) {
   1166         ((PyCoroObject *)coro)->cr_origin = NULL;
   1167     } else {
   1168         PyObject *cr_origin = compute_cr_origin(origin_depth);
   1169         ((PyCoroObject *)coro)->cr_origin = cr_origin;
   1170         if (!cr_origin) {
   1171             Py_DECREF(coro);
   1172             return NULL;
   1173         }
   1174     }
   1175 
   1176     return coro;
   1177 }
   1178 
   1179 
   1180 /* ========= Asynchronous Generators ========= */
   1181 
   1182 
   1183 typedef enum {
   1184     AWAITABLE_STATE_INIT,   /* new awaitable, has not yet been iterated */
   1185     AWAITABLE_STATE_ITER,   /* being iterated */
   1186     AWAITABLE_STATE_CLOSED, /* closed */
   1187 } AwaitableState;
   1188 
   1189 
   1190 typedef struct {
   1191     PyObject_HEAD
   1192     PyAsyncGenObject *ags_gen;
   1193 
   1194     /* Can be NULL, when in the __anext__() mode
   1195        (equivalent of "asend(None)") */
   1196     PyObject *ags_sendval;
   1197 
   1198     AwaitableState ags_state;
   1199 } PyAsyncGenASend;
   1200 
   1201 
   1202 typedef struct {
   1203     PyObject_HEAD
   1204     PyAsyncGenObject *agt_gen;
   1205 
   1206     /* Can be NULL, when in the "aclose()" mode
   1207        (equivalent of "athrow(GeneratorExit)") */
   1208     PyObject *agt_args;
   1209 
   1210     AwaitableState agt_state;
   1211 } PyAsyncGenAThrow;
   1212 
   1213 
   1214 typedef struct {
   1215     PyObject_HEAD
   1216     PyObject *agw_val;
   1217 } _PyAsyncGenWrappedValue;
   1218 
   1219 
   1220 #ifndef _PyAsyncGen_MAXFREELIST
   1221 #define _PyAsyncGen_MAXFREELIST 80
   1222 #endif
   1223 
   1224 /* Freelists boost performance 6-10%; they also reduce memory
   1225    fragmentation, as _PyAsyncGenWrappedValue and PyAsyncGenASend
   1226    are short-living objects that are instantiated for every
   1227    __anext__ call.
   1228 */
   1229 
   1230 static _PyAsyncGenWrappedValue *ag_value_freelist[_PyAsyncGen_MAXFREELIST];
   1231 static int ag_value_freelist_free = 0;
   1232 
   1233 static PyAsyncGenASend *ag_asend_freelist[_PyAsyncGen_MAXFREELIST];
   1234 static int ag_asend_freelist_free = 0;
   1235 
   1236 #define _PyAsyncGenWrappedValue_CheckExact(o) \
   1237                     (Py_TYPE(o) == &_PyAsyncGenWrappedValue_Type)
   1238 
   1239 #define PyAsyncGenASend_CheckExact(o) \
   1240                     (Py_TYPE(o) == &_PyAsyncGenASend_Type)
   1241 
   1242 
   1243 static int
   1244 async_gen_traverse(PyAsyncGenObject *gen, visitproc visit, void *arg)
   1245 {
   1246     Py_VISIT(gen->ag_finalizer);
   1247     return gen_traverse((PyGenObject*)gen, visit, arg);
   1248 }
   1249 
   1250 
   1251 static PyObject *
   1252 async_gen_repr(PyAsyncGenObject *o)
   1253 {
   1254     return PyUnicode_FromFormat("<async_generator object %S at %p>",
   1255                                 o->ag_qualname, o);
   1256 }
   1257 
   1258 
   1259 static int
   1260 async_gen_init_hooks(PyAsyncGenObject *o)
   1261 {
   1262     PyThreadState *tstate;
   1263     PyObject *finalizer;
   1264     PyObject *firstiter;
   1265 
   1266     if (o->ag_hooks_inited) {
   1267         return 0;
   1268     }
   1269 
   1270     o->ag_hooks_inited = 1;
   1271 
   1272     tstate = PyThreadState_GET();
   1273 
   1274     finalizer = tstate->async_gen_finalizer;
   1275     if (finalizer) {
   1276         Py_INCREF(finalizer);
   1277         o->ag_finalizer = finalizer;
   1278     }
   1279 
   1280     firstiter = tstate->async_gen_firstiter;
   1281     if (firstiter) {
   1282         PyObject *res;
   1283 
   1284         Py_INCREF(firstiter);
   1285         res = PyObject_CallFunctionObjArgs(firstiter, o, NULL);
   1286         Py_DECREF(firstiter);
   1287         if (res == NULL) {
   1288             return 1;
   1289         }
   1290         Py_DECREF(res);
   1291     }
   1292 
   1293     return 0;
   1294 }
   1295 
   1296 
   1297 static PyObject *
   1298 async_gen_anext(PyAsyncGenObject *o)
   1299 {
   1300     if (async_gen_init_hooks(o)) {
   1301         return NULL;
   1302     }
   1303     return async_gen_asend_new(o, NULL);
   1304 }
   1305 
   1306 
   1307 static PyObject *
   1308 async_gen_asend(PyAsyncGenObject *o, PyObject *arg)
   1309 {
   1310     if (async_gen_init_hooks(o)) {
   1311         return NULL;
   1312     }
   1313     return async_gen_asend_new(o, arg);
   1314 }
   1315 
   1316 
   1317 static PyObject *
   1318 async_gen_aclose(PyAsyncGenObject *o, PyObject *arg)
   1319 {
   1320     if (async_gen_init_hooks(o)) {
   1321         return NULL;
   1322     }
   1323     return async_gen_athrow_new(o, NULL);
   1324 }
   1325 
   1326 static PyObject *
   1327 async_gen_athrow(PyAsyncGenObject *o, PyObject *args)
   1328 {
   1329     if (async_gen_init_hooks(o)) {
   1330         return NULL;
   1331     }
   1332     return async_gen_athrow_new(o, args);
   1333 }
   1334 
   1335 
   1336 static PyGetSetDef async_gen_getsetlist[] = {
   1337     {"__name__", (getter)gen_get_name, (setter)gen_set_name,
   1338      PyDoc_STR("name of the async generator")},
   1339     {"__qualname__", (getter)gen_get_qualname, (setter)gen_set_qualname,
   1340      PyDoc_STR("qualified name of the async generator")},
   1341     {"ag_await", (getter)coro_get_cr_await, NULL,
   1342      PyDoc_STR("object being awaited on, or None")},
   1343     {NULL} /* Sentinel */
   1344 };
   1345 
   1346 static PyMemberDef async_gen_memberlist[] = {
   1347     {"ag_frame",   T_OBJECT, offsetof(PyAsyncGenObject, ag_frame),   READONLY},
   1348     {"ag_running", T_BOOL,   offsetof(PyAsyncGenObject, ag_running), READONLY},
   1349     {"ag_code",    T_OBJECT, offsetof(PyAsyncGenObject, ag_code),    READONLY},
   1350     {NULL}      /* Sentinel */
   1351 };
   1352 
   1353 PyDoc_STRVAR(async_aclose_doc,
   1354 "aclose() -> raise GeneratorExit inside generator.");
   1355 
   1356 PyDoc_STRVAR(async_asend_doc,
   1357 "asend(v) -> send 'v' in generator.");
   1358 
   1359 PyDoc_STRVAR(async_athrow_doc,
   1360 "athrow(typ[,val[,tb]]) -> raise exception in generator.");
   1361 
   1362 static PyMethodDef async_gen_methods[] = {
   1363     {"asend", (PyCFunction)async_gen_asend, METH_O, async_asend_doc},
   1364     {"athrow",(PyCFunction)async_gen_athrow, METH_VARARGS, async_athrow_doc},
   1365     {"aclose", (PyCFunction)async_gen_aclose, METH_NOARGS, async_aclose_doc},
   1366     {NULL, NULL}        /* Sentinel */
   1367 };
   1368 
   1369 
   1370 static PyAsyncMethods async_gen_as_async = {
   1371     0,                                          /* am_await */
   1372     PyObject_SelfIter,                          /* am_aiter */
   1373     (unaryfunc)async_gen_anext                  /* am_anext */
   1374 };
   1375 
   1376 
   1377 PyTypeObject PyAsyncGen_Type = {
   1378     PyVarObject_HEAD_INIT(&PyType_Type, 0)
   1379     "async_generator",                          /* tp_name */
   1380     sizeof(PyAsyncGenObject),                   /* tp_basicsize */
   1381     0,                                          /* tp_itemsize */
   1382     /* methods */
   1383     (destructor)gen_dealloc,                    /* tp_dealloc */
   1384     0,                                          /* tp_print */
   1385     0,                                          /* tp_getattr */
   1386     0,                                          /* tp_setattr */
   1387     &async_gen_as_async,                        /* tp_as_async */
   1388     (reprfunc)async_gen_repr,                   /* tp_repr */
   1389     0,                                          /* tp_as_number */
   1390     0,                                          /* tp_as_sequence */
   1391     0,                                          /* tp_as_mapping */
   1392     0,                                          /* tp_hash */
   1393     0,                                          /* tp_call */
   1394     0,                                          /* tp_str */
   1395     PyObject_GenericGetAttr,                    /* tp_getattro */
   1396     0,                                          /* tp_setattro */
   1397     0,                                          /* tp_as_buffer */
   1398     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
   1399         Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
   1400     0,                                          /* tp_doc */
   1401     (traverseproc)async_gen_traverse,           /* tp_traverse */
   1402     0,                                          /* tp_clear */
   1403     0,                                          /* tp_richcompare */
   1404     offsetof(PyAsyncGenObject, ag_weakreflist), /* tp_weaklistoffset */
   1405     0,                                          /* tp_iter */
   1406     0,                                          /* tp_iternext */
   1407     async_gen_methods,                          /* tp_methods */
   1408     async_gen_memberlist,                       /* tp_members */
   1409     async_gen_getsetlist,                       /* tp_getset */
   1410     0,                                          /* tp_base */
   1411     0,                                          /* tp_dict */
   1412     0,                                          /* tp_descr_get */
   1413     0,                                          /* tp_descr_set */
   1414     0,                                          /* tp_dictoffset */
   1415     0,                                          /* tp_init */
   1416     0,                                          /* tp_alloc */
   1417     0,                                          /* tp_new */
   1418     0,                                          /* tp_free */
   1419     0,                                          /* tp_is_gc */
   1420     0,                                          /* tp_bases */
   1421     0,                                          /* tp_mro */
   1422     0,                                          /* tp_cache */
   1423     0,                                          /* tp_subclasses */
   1424     0,                                          /* tp_weaklist */
   1425     0,                                          /* tp_del */
   1426     0,                                          /* tp_version_tag */
   1427     _PyGen_Finalize,                            /* tp_finalize */
   1428 };
   1429 
   1430 
   1431 PyObject *
   1432 PyAsyncGen_New(PyFrameObject *f, PyObject *name, PyObject *qualname)
   1433 {
   1434     PyAsyncGenObject *o;
   1435     o = (PyAsyncGenObject *)gen_new_with_qualname(
   1436         &PyAsyncGen_Type, f, name, qualname);
   1437     if (o == NULL) {
   1438         return NULL;
   1439     }
   1440     o->ag_finalizer = NULL;
   1441     o->ag_closed = 0;
   1442     o->ag_hooks_inited = 0;
   1443     return (PyObject*)o;
   1444 }
   1445 
   1446 
   1447 int
   1448 PyAsyncGen_ClearFreeLists(void)
   1449 {
   1450     int ret = ag_value_freelist_free + ag_asend_freelist_free;
   1451 
   1452     while (ag_value_freelist_free) {
   1453         _PyAsyncGenWrappedValue *o;
   1454         o = ag_value_freelist[--ag_value_freelist_free];
   1455         assert(_PyAsyncGenWrappedValue_CheckExact(o));
   1456         PyObject_GC_Del(o);
   1457     }
   1458 
   1459     while (ag_asend_freelist_free) {
   1460         PyAsyncGenASend *o;
   1461         o = ag_asend_freelist[--ag_asend_freelist_free];
   1462         assert(Py_TYPE(o) == &_PyAsyncGenASend_Type);
   1463         PyObject_GC_Del(o);
   1464     }
   1465 
   1466     return ret;
   1467 }
   1468 
   1469 void
   1470 PyAsyncGen_Fini(void)
   1471 {
   1472     PyAsyncGen_ClearFreeLists();
   1473 }
   1474 
   1475 
   1476 static PyObject *
   1477 async_gen_unwrap_value(PyAsyncGenObject *gen, PyObject *result)
   1478 {
   1479     if (result == NULL) {
   1480         if (!PyErr_Occurred()) {
   1481             PyErr_SetNone(PyExc_StopAsyncIteration);
   1482         }
   1483 
   1484         if (PyErr_ExceptionMatches(PyExc_StopAsyncIteration)
   1485             || PyErr_ExceptionMatches(PyExc_GeneratorExit)
   1486         ) {
   1487             gen->ag_closed = 1;
   1488         }
   1489 
   1490         return NULL;
   1491     }
   1492 
   1493     if (_PyAsyncGenWrappedValue_CheckExact(result)) {
   1494         /* async yield */
   1495         _PyGen_SetStopIterationValue(((_PyAsyncGenWrappedValue*)result)->agw_val);
   1496         Py_DECREF(result);
   1497         return NULL;
   1498     }
   1499 
   1500     return result;
   1501 }
   1502 
   1503 
   1504 /* ---------- Async Generator ASend Awaitable ------------ */
   1505 
   1506 
   1507 static void
   1508 async_gen_asend_dealloc(PyAsyncGenASend *o)
   1509 {
   1510     _PyObject_GC_UNTRACK((PyObject *)o);
   1511     Py_CLEAR(o->ags_gen);
   1512     Py_CLEAR(o->ags_sendval);
   1513     if (ag_asend_freelist_free < _PyAsyncGen_MAXFREELIST) {
   1514         assert(PyAsyncGenASend_CheckExact(o));
   1515         ag_asend_freelist[ag_asend_freelist_free++] = o;
   1516     } else {
   1517         PyObject_GC_Del(o);
   1518     }
   1519 }
   1520 
   1521 static int
   1522 async_gen_asend_traverse(PyAsyncGenASend *o, visitproc visit, void *arg)
   1523 {
   1524     Py_VISIT(o->ags_gen);
   1525     Py_VISIT(o->ags_sendval);
   1526     return 0;
   1527 }
   1528 
   1529 
   1530 static PyObject *
   1531 async_gen_asend_send(PyAsyncGenASend *o, PyObject *arg)
   1532 {
   1533     PyObject *result;
   1534 
   1535     if (o->ags_state == AWAITABLE_STATE_CLOSED) {
   1536         PyErr_SetNone(PyExc_StopIteration);
   1537         return NULL;
   1538     }
   1539 
   1540     if (o->ags_state == AWAITABLE_STATE_INIT) {
   1541         if (arg == NULL || arg == Py_None) {
   1542             arg = o->ags_sendval;
   1543         }
   1544         o->ags_state = AWAITABLE_STATE_ITER;
   1545     }
   1546 
   1547     result = gen_send_ex((PyGenObject*)o->ags_gen, arg, 0, 0);
   1548     result = async_gen_unwrap_value(o->ags_gen, result);
   1549 
   1550     if (result == NULL) {
   1551         o->ags_state = AWAITABLE_STATE_CLOSED;
   1552     }
   1553 
   1554     return result;
   1555 }
   1556 
   1557 
   1558 static PyObject *
   1559 async_gen_asend_iternext(PyAsyncGenASend *o)
   1560 {
   1561     return async_gen_asend_send(o, NULL);
   1562 }
   1563 
   1564 
   1565 static PyObject *
   1566 async_gen_asend_throw(PyAsyncGenASend *o, PyObject *args)
   1567 {
   1568     PyObject *result;
   1569 
   1570     if (o->ags_state == AWAITABLE_STATE_CLOSED) {
   1571         PyErr_SetNone(PyExc_StopIteration);
   1572         return NULL;
   1573     }
   1574 
   1575     result = gen_throw((PyGenObject*)o->ags_gen, args);
   1576     result = async_gen_unwrap_value(o->ags_gen, result);
   1577 
   1578     if (result == NULL) {
   1579         o->ags_state = AWAITABLE_STATE_CLOSED;
   1580     }
   1581 
   1582     return result;
   1583 }
   1584 
   1585 
   1586 static PyObject *
   1587 async_gen_asend_close(PyAsyncGenASend *o, PyObject *args)
   1588 {
   1589     o->ags_state = AWAITABLE_STATE_CLOSED;
   1590     Py_RETURN_NONE;
   1591 }
   1592 
   1593 
   1594 static PyMethodDef async_gen_asend_methods[] = {
   1595     {"send", (PyCFunction)async_gen_asend_send, METH_O, send_doc},
   1596     {"throw", (PyCFunction)async_gen_asend_throw, METH_VARARGS, throw_doc},
   1597     {"close", (PyCFunction)async_gen_asend_close, METH_NOARGS, close_doc},
   1598     {NULL, NULL}        /* Sentinel */
   1599 };
   1600 
   1601 
   1602 static PyAsyncMethods async_gen_asend_as_async = {
   1603     PyObject_SelfIter,                          /* am_await */
   1604     0,                                          /* am_aiter */
   1605     0                                           /* am_anext */
   1606 };
   1607 
   1608 
   1609 PyTypeObject _PyAsyncGenASend_Type = {
   1610     PyVarObject_HEAD_INIT(&PyType_Type, 0)
   1611     "async_generator_asend",                    /* tp_name */
   1612     sizeof(PyAsyncGenASend),                    /* tp_basicsize */
   1613     0,                                          /* tp_itemsize */
   1614     /* methods */
   1615     (destructor)async_gen_asend_dealloc,        /* tp_dealloc */
   1616     0,                                          /* tp_print */
   1617     0,                                          /* tp_getattr */
   1618     0,                                          /* tp_setattr */
   1619     &async_gen_asend_as_async,                  /* tp_as_async */
   1620     0,                                          /* tp_repr */
   1621     0,                                          /* tp_as_number */
   1622     0,                                          /* tp_as_sequence */
   1623     0,                                          /* tp_as_mapping */
   1624     0,                                          /* tp_hash */
   1625     0,                                          /* tp_call */
   1626     0,                                          /* tp_str */
   1627     PyObject_GenericGetAttr,                    /* tp_getattro */
   1628     0,                                          /* tp_setattro */
   1629     0,                                          /* tp_as_buffer */
   1630     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
   1631     0,                                          /* tp_doc */
   1632     (traverseproc)async_gen_asend_traverse,     /* tp_traverse */
   1633     0,                                          /* tp_clear */
   1634     0,                                          /* tp_richcompare */
   1635     0,                                          /* tp_weaklistoffset */
   1636     PyObject_SelfIter,                          /* tp_iter */
   1637     (iternextfunc)async_gen_asend_iternext,     /* tp_iternext */
   1638     async_gen_asend_methods,                    /* tp_methods */
   1639     0,                                          /* tp_members */
   1640     0,                                          /* tp_getset */
   1641     0,                                          /* tp_base */
   1642     0,                                          /* tp_dict */
   1643     0,                                          /* tp_descr_get */
   1644     0,                                          /* tp_descr_set */
   1645     0,                                          /* tp_dictoffset */
   1646     0,                                          /* tp_init */
   1647     0,                                          /* tp_alloc */
   1648     0,                                          /* tp_new */
   1649 };
   1650 
   1651 
   1652 static PyObject *
   1653 async_gen_asend_new(PyAsyncGenObject *gen, PyObject *sendval)
   1654 {
   1655     PyAsyncGenASend *o;
   1656     if (ag_asend_freelist_free) {
   1657         ag_asend_freelist_free--;
   1658         o = ag_asend_freelist[ag_asend_freelist_free];
   1659         _Py_NewReference((PyObject *)o);
   1660     } else {
   1661         o = PyObject_GC_New(PyAsyncGenASend, &_PyAsyncGenASend_Type);
   1662         if (o == NULL) {
   1663             return NULL;
   1664         }
   1665     }
   1666 
   1667     Py_INCREF(gen);
   1668     o->ags_gen = gen;
   1669 
   1670     Py_XINCREF(sendval);
   1671     o->ags_sendval = sendval;
   1672 
   1673     o->ags_state = AWAITABLE_STATE_INIT;
   1674 
   1675     _PyObject_GC_TRACK((PyObject*)o);
   1676     return (PyObject*)o;
   1677 }
   1678 
   1679 
   1680 /* ---------- Async Generator Value Wrapper ------------ */
   1681 
   1682 
   1683 static void
   1684 async_gen_wrapped_val_dealloc(_PyAsyncGenWrappedValue *o)
   1685 {
   1686     _PyObject_GC_UNTRACK((PyObject *)o);
   1687     Py_CLEAR(o->agw_val);
   1688     if (ag_value_freelist_free < _PyAsyncGen_MAXFREELIST) {
   1689         assert(_PyAsyncGenWrappedValue_CheckExact(o));
   1690         ag_value_freelist[ag_value_freelist_free++] = o;
   1691     } else {
   1692         PyObject_GC_Del(o);
   1693     }
   1694 }
   1695 
   1696 
   1697 static int
   1698 async_gen_wrapped_val_traverse(_PyAsyncGenWrappedValue *o,
   1699                                visitproc visit, void *arg)
   1700 {
   1701     Py_VISIT(o->agw_val);
   1702     return 0;
   1703 }
   1704 
   1705 
   1706 PyTypeObject _PyAsyncGenWrappedValue_Type = {
   1707     PyVarObject_HEAD_INIT(&PyType_Type, 0)
   1708     "async_generator_wrapped_value",            /* tp_name */
   1709     sizeof(_PyAsyncGenWrappedValue),            /* tp_basicsize */
   1710     0,                                          /* tp_itemsize */
   1711     /* methods */
   1712     (destructor)async_gen_wrapped_val_dealloc,  /* tp_dealloc */
   1713     0,                                          /* tp_print */
   1714     0,                                          /* tp_getattr */
   1715     0,                                          /* tp_setattr */
   1716     0,                                          /* tp_as_async */
   1717     0,                                          /* tp_repr */
   1718     0,                                          /* tp_as_number */
   1719     0,                                          /* tp_as_sequence */
   1720     0,                                          /* tp_as_mapping */
   1721     0,                                          /* tp_hash */
   1722     0,                                          /* tp_call */
   1723     0,                                          /* tp_str */
   1724     PyObject_GenericGetAttr,                    /* tp_getattro */
   1725     0,                                          /* tp_setattro */
   1726     0,                                          /* tp_as_buffer */
   1727     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
   1728     0,                                          /* tp_doc */
   1729     (traverseproc)async_gen_wrapped_val_traverse, /* tp_traverse */
   1730     0,                                          /* tp_clear */
   1731     0,                                          /* tp_richcompare */
   1732     0,                                          /* tp_weaklistoffset */
   1733     0,                                          /* tp_iter */
   1734     0,                                          /* tp_iternext */
   1735     0,                                          /* tp_methods */
   1736     0,                                          /* tp_members */
   1737     0,                                          /* tp_getset */
   1738     0,                                          /* tp_base */
   1739     0,                                          /* tp_dict */
   1740     0,                                          /* tp_descr_get */
   1741     0,                                          /* tp_descr_set */
   1742     0,                                          /* tp_dictoffset */
   1743     0,                                          /* tp_init */
   1744     0,                                          /* tp_alloc */
   1745     0,                                          /* tp_new */
   1746 };
   1747 
   1748 
   1749 PyObject *
   1750 _PyAsyncGenValueWrapperNew(PyObject *val)
   1751 {
   1752     _PyAsyncGenWrappedValue *o;
   1753     assert(val);
   1754 
   1755     if (ag_value_freelist_free) {
   1756         ag_value_freelist_free--;
   1757         o = ag_value_freelist[ag_value_freelist_free];
   1758         assert(_PyAsyncGenWrappedValue_CheckExact(o));
   1759         _Py_NewReference((PyObject*)o);
   1760     } else {
   1761         o = PyObject_GC_New(_PyAsyncGenWrappedValue,
   1762                             &_PyAsyncGenWrappedValue_Type);
   1763         if (o == NULL) {
   1764             return NULL;
   1765         }
   1766     }
   1767     o->agw_val = val;
   1768     Py_INCREF(val);
   1769     _PyObject_GC_TRACK((PyObject*)o);
   1770     return (PyObject*)o;
   1771 }
   1772 
   1773 
   1774 /* ---------- Async Generator AThrow awaitable ------------ */
   1775 
   1776 
   1777 static void
   1778 async_gen_athrow_dealloc(PyAsyncGenAThrow *o)
   1779 {
   1780     _PyObject_GC_UNTRACK((PyObject *)o);
   1781     Py_CLEAR(o->agt_gen);
   1782     Py_CLEAR(o->agt_args);
   1783     PyObject_GC_Del(o);
   1784 }
   1785 
   1786 
   1787 static int
   1788 async_gen_athrow_traverse(PyAsyncGenAThrow *o, visitproc visit, void *arg)
   1789 {
   1790     Py_VISIT(o->agt_gen);
   1791     Py_VISIT(o->agt_args);
   1792     return 0;
   1793 }
   1794 
   1795 
   1796 static PyObject *
   1797 async_gen_athrow_send(PyAsyncGenAThrow *o, PyObject *arg)
   1798 {
   1799     PyGenObject *gen = (PyGenObject*)o->agt_gen;
   1800     PyFrameObject *f = gen->gi_frame;
   1801     PyObject *retval;
   1802 
   1803     if (f == NULL || f->f_stacktop == NULL ||
   1804             o->agt_state == AWAITABLE_STATE_CLOSED) {
   1805         PyErr_SetNone(PyExc_StopIteration);
   1806         return NULL;
   1807     }
   1808 
   1809     if (o->agt_state == AWAITABLE_STATE_INIT) {
   1810         if (o->agt_gen->ag_closed) {
   1811             PyErr_SetNone(PyExc_StopIteration);
   1812             return NULL;
   1813         }
   1814 
   1815         if (arg != Py_None) {
   1816             PyErr_SetString(PyExc_RuntimeError, NON_INIT_CORO_MSG);
   1817             return NULL;
   1818         }
   1819 
   1820         o->agt_state = AWAITABLE_STATE_ITER;
   1821 
   1822         if (o->agt_args == NULL) {
   1823             /* aclose() mode */
   1824             o->agt_gen->ag_closed = 1;
   1825 
   1826             retval = _gen_throw((PyGenObject *)gen,
   1827                                 0,  /* Do not close generator when
   1828                                        PyExc_GeneratorExit is passed */
   1829                                 PyExc_GeneratorExit, NULL, NULL);
   1830 
   1831             if (retval && _PyAsyncGenWrappedValue_CheckExact(retval)) {
   1832                 Py_DECREF(retval);
   1833                 goto yield_close;
   1834             }
   1835         } else {
   1836             PyObject *typ;
   1837             PyObject *tb = NULL;
   1838             PyObject *val = NULL;
   1839 
   1840             if (!PyArg_UnpackTuple(o->agt_args, "athrow", 1, 3,
   1841                                    &typ, &val, &tb)) {
   1842                 return NULL;
   1843             }
   1844 
   1845             retval = _gen_throw((PyGenObject *)gen,
   1846                                 0,  /* Do not close generator when
   1847                                        PyExc_GeneratorExit is passed */
   1848                                 typ, val, tb);
   1849             retval = async_gen_unwrap_value(o->agt_gen, retval);
   1850         }
   1851         if (retval == NULL) {
   1852             goto check_error;
   1853         }
   1854         return retval;
   1855     }
   1856 
   1857     assert(o->agt_state == AWAITABLE_STATE_ITER);
   1858 
   1859     retval = gen_send_ex((PyGenObject *)gen, arg, 0, 0);
   1860     if (o->agt_args) {
   1861         return async_gen_unwrap_value(o->agt_gen, retval);
   1862     } else {
   1863         /* aclose() mode */
   1864         if (retval) {
   1865             if (_PyAsyncGenWrappedValue_CheckExact(retval)) {
   1866                 Py_DECREF(retval);
   1867                 goto yield_close;
   1868             }
   1869             else {
   1870                 return retval;
   1871             }
   1872         }
   1873         else {
   1874             goto check_error;
   1875         }
   1876     }
   1877 
   1878 yield_close:
   1879     PyErr_SetString(
   1880         PyExc_RuntimeError, ASYNC_GEN_IGNORED_EXIT_MSG);
   1881     return NULL;
   1882 
   1883 check_error:
   1884     if (PyErr_ExceptionMatches(PyExc_StopAsyncIteration)) {
   1885         o->agt_state = AWAITABLE_STATE_CLOSED;
   1886         if (o->agt_args == NULL) {
   1887             /* when aclose() is called we don't want to propagate
   1888                StopAsyncIteration; just raise StopIteration, signalling
   1889                that 'aclose()' is done. */
   1890             PyErr_Clear();
   1891             PyErr_SetNone(PyExc_StopIteration);
   1892         }
   1893     }
   1894     else if (PyErr_ExceptionMatches(PyExc_GeneratorExit)) {
   1895         o->agt_state = AWAITABLE_STATE_CLOSED;
   1896         PyErr_Clear();          /* ignore these errors */
   1897         PyErr_SetNone(PyExc_StopIteration);
   1898     }
   1899     return NULL;
   1900 }
   1901 
   1902 
   1903 static PyObject *
   1904 async_gen_athrow_throw(PyAsyncGenAThrow *o, PyObject *args)
   1905 {
   1906     PyObject *retval;
   1907 
   1908     if (o->agt_state == AWAITABLE_STATE_INIT) {
   1909         PyErr_SetString(PyExc_RuntimeError, NON_INIT_CORO_MSG);
   1910         return NULL;
   1911     }
   1912 
   1913     if (o->agt_state == AWAITABLE_STATE_CLOSED) {
   1914         PyErr_SetNone(PyExc_StopIteration);
   1915         return NULL;
   1916     }
   1917 
   1918     retval = gen_throw((PyGenObject*)o->agt_gen, args);
   1919     if (o->agt_args) {
   1920         return async_gen_unwrap_value(o->agt_gen, retval);
   1921     } else {
   1922         /* aclose() mode */
   1923         if (retval && _PyAsyncGenWrappedValue_CheckExact(retval)) {
   1924             Py_DECREF(retval);
   1925             PyErr_SetString(PyExc_RuntimeError, ASYNC_GEN_IGNORED_EXIT_MSG);
   1926             return NULL;
   1927         }
   1928         return retval;
   1929     }
   1930 }
   1931 
   1932 
   1933 static PyObject *
   1934 async_gen_athrow_iternext(PyAsyncGenAThrow *o)
   1935 {
   1936     return async_gen_athrow_send(o, Py_None);
   1937 }
   1938 
   1939 
   1940 static PyObject *
   1941 async_gen_athrow_close(PyAsyncGenAThrow *o, PyObject *args)
   1942 {
   1943     o->agt_state = AWAITABLE_STATE_CLOSED;
   1944     Py_RETURN_NONE;
   1945 }
   1946 
   1947 
   1948 static PyMethodDef async_gen_athrow_methods[] = {
   1949     {"send", (PyCFunction)async_gen_athrow_send, METH_O, send_doc},
   1950     {"throw", (PyCFunction)async_gen_athrow_throw, METH_VARARGS, throw_doc},
   1951     {"close", (PyCFunction)async_gen_athrow_close, METH_NOARGS, close_doc},
   1952     {NULL, NULL}        /* Sentinel */
   1953 };
   1954 
   1955 
   1956 static PyAsyncMethods async_gen_athrow_as_async = {
   1957     PyObject_SelfIter,                          /* am_await */
   1958     0,                                          /* am_aiter */
   1959     0                                           /* am_anext */
   1960 };
   1961 
   1962 
   1963 PyTypeObject _PyAsyncGenAThrow_Type = {
   1964     PyVarObject_HEAD_INIT(&PyType_Type, 0)
   1965     "async_generator_athrow",                   /* tp_name */
   1966     sizeof(PyAsyncGenAThrow),                   /* tp_basicsize */
   1967     0,                                          /* tp_itemsize */
   1968     /* methods */
   1969     (destructor)async_gen_athrow_dealloc,       /* tp_dealloc */
   1970     0,                                          /* tp_print */
   1971     0,                                          /* tp_getattr */
   1972     0,                                          /* tp_setattr */
   1973     &async_gen_athrow_as_async,                 /* tp_as_async */
   1974     0,                                          /* tp_repr */
   1975     0,                                          /* tp_as_number */
   1976     0,                                          /* tp_as_sequence */
   1977     0,                                          /* tp_as_mapping */
   1978     0,                                          /* tp_hash */
   1979     0,                                          /* tp_call */
   1980     0,                                          /* tp_str */
   1981     PyObject_GenericGetAttr,                    /* tp_getattro */
   1982     0,                                          /* tp_setattro */
   1983     0,                                          /* tp_as_buffer */
   1984     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
   1985     0,                                          /* tp_doc */
   1986     (traverseproc)async_gen_athrow_traverse,    /* tp_traverse */
   1987     0,                                          /* tp_clear */
   1988     0,                                          /* tp_richcompare */
   1989     0,                                          /* tp_weaklistoffset */
   1990     PyObject_SelfIter,                          /* tp_iter */
   1991     (iternextfunc)async_gen_athrow_iternext,    /* tp_iternext */
   1992     async_gen_athrow_methods,                   /* tp_methods */
   1993     0,                                          /* tp_members */
   1994     0,                                          /* tp_getset */
   1995     0,                                          /* tp_base */
   1996     0,                                          /* tp_dict */
   1997     0,                                          /* tp_descr_get */
   1998     0,                                          /* tp_descr_set */
   1999     0,                                          /* tp_dictoffset */
   2000     0,                                          /* tp_init */
   2001     0,                                          /* tp_alloc */
   2002     0,                                          /* tp_new */
   2003 };
   2004 
   2005 
   2006 static PyObject *
   2007 async_gen_athrow_new(PyAsyncGenObject *gen, PyObject *args)
   2008 {
   2009     PyAsyncGenAThrow *o;
   2010     o = PyObject_GC_New(PyAsyncGenAThrow, &_PyAsyncGenAThrow_Type);
   2011     if (o == NULL) {
   2012         return NULL;
   2013     }
   2014     o->agt_gen = gen;
   2015     o->agt_args = args;
   2016     o->agt_state = AWAITABLE_STATE_INIT;
   2017     Py_INCREF(gen);
   2018     Py_XINCREF(args);
   2019     _PyObject_GC_TRACK((PyObject*)o);
   2020     return (PyObject*)o;
   2021 }
   2022