PEP 342 implementation. Per Guido's comments, the generator throw()

method still needs to support string exceptions, and allow None for the
third argument.  Documentation updates are needed, too.

1 files changed, 234 insertions, 5 deletions

diff --git a/Objects/genobject.c b/Objects/genobject.c
index 174c697..d281274 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -15,15 +15,31 @@ gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
 static void
 gen_dealloc(PyGenObject *gen)
 {
+	PyObject *self = (PyObject *) gen;
+
 	_PyObject_GC_UNTRACK(gen);
+
 	if (gen->gi_weakreflist != NULL)
 		PyObject_ClearWeakRefs((PyObject *) gen);
-	Py_DECREF(gen->gi_frame);
+
+
+	_PyObject_GC_TRACK(self);
+
+	if (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_XDECREF(gen->gi_frame);
 	PyObject_GC_Del(gen);
 }
 
+
 static PyObject *
-gen_iternext(PyGenObject *gen)
+gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
 {
 	PyThreadState *tstate = PyThreadState_GET();
 	PyFrameObject *f = gen->gi_frame;
@@ -34,8 +50,24 @@ gen_iternext(PyGenObject *gen)
 				"generator already executing");
 		return NULL;
 	}
-	if (f->f_stacktop == NULL)
+	if ((PyObject *)f == Py_None || 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. */
@@ -44,7 +76,7 @@ gen_iternext(PyGenObject *gen)
 	f->f_back = tstate->frame;
 
 	gen->gi_running = 1;
-	result = PyEval_EvalFrame(f);
+	result = PyEval_EvalFrameEx(f, exc);
 	gen->gi_running = 0;
 
 	/* Don't keep the reference to f_back any longer than necessary.  It
@@ -58,17 +90,199 @@ gen_iternext(PyGenObject *gen)
 	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 = (PyFrameObject *)Py_None;
+		Py_INCREF(Py_None);
 	}
 
 	return result;
 }
 
+PyDoc_STRVAR(send_doc,
+"send(arg) -> send 'arg' into generator, 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 ((PyObject *)gen->gi_frame == Py_None || 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((PyGenObject *)self, NULL);
+
+	if (res == NULL)
+		PyErr_WriteUnraisable((PyObject *)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.
+         */
+        {
+                int 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, 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_ParseTuple(args, "O|OO:throw", &typ, &val, &tb))
+		return NULL;
+
+	if (tb && !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 (PyClass_Check(typ)) {
+		PyErr_NormalizeException(&typ, &val, &tb);
+	}
+
+	else if (PyInstance_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> */
+			val = typ;
+			typ = (PyObject*) ((PyInstanceObject*)typ)->in_class;
+			Py_INCREF(typ);
+		}
+	}
+	else {
+		/* Not something you can raise.  You get an exception
+		   anyway, just not what you specified :-) */
+		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 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 */
@@ -99,11 +313,26 @@ PyTypeObject PyGen_Type = {
 	offsetof(PyGenObject, gi_weakreflist),	/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)gen_iternext,		/* tp_iternext */
-	0,					/* tp_methods */
+	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 *