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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 int
gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
{
Py_VISIT((PyObject *)gen->gi_frame);
Py_VISIT(gen->gi_code);
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 */
Py_TYPE(gen)->tp_del(self);
if (self->ob_refcnt > 0)
return; /* resurrected. :( */
}
_PyObject_GC_UNTRACK(self);
Py_CLEAR(gen->gi_frame);
Py_CLEAR(gen->gi_code);
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 PyObject *
gen_repr(PyGenObject *gen)
{
return PyUnicode_FromFormat("<generator object %S at %p>",
((PyCodeObject *)gen->gi_code)->co_name,
gen);
}
static PyObject *
gen_get_name(PyGenObject *gen)
{
PyObject *name = ((PyCodeObject *)gen->gi_code)->co_name;
Py_INCREF(name);
return name;
}
PyDoc_STRVAR(gen__name__doc__,
"Return the name of the generator's associated code object.");
static PyGetSetDef gen_getsetlist[] = {
{"__name__", (getter)gen_get_name, NULL, gen__name__doc__},
{NULL}
};
static PyMemberDef gen_memberlist[] = {
{"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), READONLY},
{"gi_running", T_INT, offsetof(PyGenObject, gi_running), READONLY},
{"gi_code", T_OBJECT, offsetof(PyGenObject, gi_code), READONLY},
{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 = {
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_reserved */
(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,/* tp_flags */
0, /* tp_doc */
(traverseproc)gen_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)gen_iternext, /* tp_iternext */
gen_methods, /* tp_methods */
gen_memberlist, /* tp_members */
gen_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
0, /* tp_free */
0, /* tp_is_gc */
0, /* tp_bases */
0, /* tp_mro */
0, /* tp_cache */
0, /* tp_subclasses */
0, /* tp_weaklist */
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;
Py_INCREF(f->f_code);
gen->gi_code = (PyObject *)(f->f_code);
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)
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;
}
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