/* Generator object implementation */

#include "Python.h"

#include "frameobject.h"

#include "genobject.h"

#include "ceval.h"

#include "structmember.h"

#include "opcode.h"

static int

gen_traverse(PyGenObject *gen, visitproc visit, void *arg)

{

Py_VISIT((PyObject *)gen->gi_frame);

return 0;

}

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 (gen->gi_frame != NULL && gen->gi_frame->f_stacktop != NULL) {

/* Generator is paused, so we need to close */

gen->ob_type->tp_del(self);

if (self->ob_refcnt > 0)

return; /* resurrected. :( */

}

_PyObject_GC_UNTRACK(self);

Py_CLEAR(gen->gi_frame);

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 == Py_None && f->f_stacktop == NULL) {

Py_DECREF(result);

result = NULL;

/* Set exception if not called by gen_iternext() */

if (arg)

PyErr_SetNone(PyExc_StopIteration);

}

if (!result || f->f_stacktop == NULL) {

/* generator can't be rerun, so release the frame */

Py_DECREF(f);

gen->gi_frame = NULL;

}

return result;

}

PyDoc_STRVAR(send_doc,

"send(arg) -> send 'arg' into generator,\n\

return next yielded value or raise StopIteration.");

static PyObject *

gen_send(PyGenObject *gen, PyObject *arg)

{

return gen_send_ex(gen, arg, 0);

}

PyDoc_STRVAR(close_doc,

"close(arg) -> raise GeneratorExit inside generator.");

static PyObject *

gen_close(PyGenObject *gen, PyObject *args)

{

PyObject *retval;

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;

}

static void

gen_del(PyObject *self)

{

PyObject *res;

PyObject *error_type, *error_value, *error_traceback;

PyGenObject *gen = (PyGenObject *)self;

if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)

/* Generator isn't paused, so no need to close */

return;

/* Temporarily resurrect the object. */

assert(self->ob_refcnt == 0);

self->ob_refcnt = 1;

/* 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);

/* Undo the temporary resurrection; can't use DECREF here, it would

* cause a recursive call.

*/

assert(self->ob_refcnt > 0);

if (--self->ob_refcnt == 0)

return; /* this is the normal path out */

/* close() resurrected it! Make it look like the original Py_DECREF

* never happened.

*/

{

Py_ssize_t refcnt = self->ob_refcnt;

_Py_NewReference(self);

self->ob_refcnt = refcnt;

}

assert(PyType_IS_GC(self->ob_type) &&

_Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);

/* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so

* we need to undo that. */

_Py_DEC_REFTOTAL;

/* If Py_TRACE_REFS, _Py_NewReference re-added self to the object

* chain, so no more to do there.

* If COUNT_ALLOCS, the original decref bumped tp_frees, and

* _Py_NewReference bumped tp_allocs: both of those need to be

* undone.

*/

#ifdef COUNT_ALLOCS

--self->ob_type->tp_frees;

--self->ob_type->tp_allocs;

#endif

}

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;

if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb))

return NULL;

/* 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);

}

}

else {

/* Not something you can raise. throw() fails. */

PyErr_Format(PyExc_TypeError,

"exceptions must be classes or instances "

"deriving from BaseException, not %s",

typ->ob_type->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)

{

return gen_send_ex(gen, NULL, 0);

}

static PyMemberDef gen_memberlist[] = {

{"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), RO},

{"gi_running", T_INT, offsetof(PyGenObject, gi_running), RO},

{NULL} /* Sentinel */

};

static PyMethodDef gen_methods[] = {

{"send",(PyCFunction)gen_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 = {

PyObject_HEAD_INIT(&PyType_Type)

0, /* ob_size */

"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_compare */

0, /* 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,/* tp_flags */

0, /* tp_doc */

(traverseproc)gen_traverse, /* tp_traverse */

0, /* tp_clear */

0, /* tp_richcompare */

offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */

PyObject_SelfIter, /* tp_iter */

(iternextfunc)gen_iternext, /* tp_iternext */

gen_methods, /* tp_methods */

gen_memberlist, /* tp_members */

0, /* 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 */

gen_del, /* tp_del */

};

PyObject *

PyGen_New(PyFrameObject *f)

{

PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);

if (gen == NULL) {

Py_DECREF(f);

return NULL;

}

gen->gi_frame = f;

gen->gi_running = 0;

gen->gi_weakreflist = NULL;

_PyObject_GC_TRACK(gen);

return (PyObject *)gen;

}

int

PyGen_NeedsFinalizing(PyGenObject *gen)

{

int i;

PyFrameObject *f = gen->gi_frame;

if (f == NULL || f->f_stacktop == NULL || f->f_iblock <= 0)

return 0; /* no frame or empty blockstack == no finalization */

/* Any block type besides a loop requires cleanup. */

i = f->f_iblock;

while (--i >= 0) {

if (f->f_blockstack[i].b_type != SETUP_LOOP)

return 1;

}

/* No blocks except loops, it's safe to skip finalization. */

return 0;

}