/* 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);

	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, 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)

{

	char *code_name;

	code_name = PyString_AsString(((PyCodeObject *)gen->gi_code)->co_name);

	if (code_name == NULL)

		return NULL;

	return PyString_FromFormat("<generator object %.200s at %p>",

				   code_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, NULL, gen__name__doc__},

	{NULL}

};

static PyMemberDef gen_memberlist[] = {

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

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

        {"gi_code",     T_OBJECT, offsetof(PyGenObject, gi_code),  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 = {

	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_compare */

	(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 || 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;

}