Convert iterator __len__() methods to a private API.

8 files changed, 111 insertions, 75 deletions

diff --git a/Objects/abstract.c b/Objects/abstract.c
index 94af3da..1f8feb5 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -81,6 +81,31 @@ PyObject_Length(PyObject *o)
 }
 #define PyObject_Length PyObject_Size
 
+int
+_PyObject_LengthCue(PyObject *o)
+{
+	int rv = PyObject_Size(o);
+	if (rv != -1)
+		return rv;
+	if (PyErr_ExceptionMatches(PyExc_TypeError) ||
+	    PyErr_ExceptionMatches(PyExc_AttributeError)) {
+		PyObject *err_type, *err_value, *err_tb, *ro;
+
+		PyErr_Fetch(&err_type, &err_value, &err_tb);
+		ro = PyObject_CallMethod(o, "_length_cue", NULL);
+		if (ro != NULL) {
+			rv = (int)PyInt_AsLong(ro);
+			Py_DECREF(ro);
+			Py_XDECREF(err_type);
+			Py_XDECREF(err_value);
+			Py_XDECREF(err_tb);
+			return rv;
+		}
+		PyErr_Restore(err_type, err_value, err_tb);
+	}
+	return -1;
+}
+
 PyObject *
 PyObject_GetItem(PyObject *o, PyObject *key)
 {
@@ -1399,7 +1424,7 @@ PySequence_Tuple(PyObject *v)
 		return NULL;
 
 	/* Guess result size and allocate space. */
-	n = PyObject_Size(v);
+	n = _PyObject_LengthCue(v);
 	if (n < 0) {
 		if (!PyErr_ExceptionMatches(PyExc_TypeError)  &&
 		    !PyErr_ExceptionMatches(PyExc_AttributeError)) {
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index e90aca4..42e55e8 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2054,17 +2054,20 @@ dictiter_dealloc(dictiterobject *di)
 	PyObject_Del(di);
 }
 
-static int
+static PyObject *
 dictiter_len(dictiterobject *di)
 {
+	int len = 0;
 	if (di->di_dict != NULL && di->di_used == di->di_dict->ma_used)
-		return di->len;
-	return 0;
+		len = di->len;
+	return PyInt_FromLong(len);
 }
 
-static PySequenceMethods dictiter_as_sequence = {
-	(inquiry)dictiter_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef dictiter_methods[] = {
+	{"_length_cue", (PyCFunction)dictiter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 static PyObject *dictiter_iternextkey(dictiterobject *di)
@@ -2120,7 +2123,7 @@ PyTypeObject PyDictIterKey_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&dictiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -2136,6 +2139,8 @@ PyTypeObject PyDictIterKey_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)dictiter_iternextkey,	/* tp_iternext */
+	dictiter_methods,			/* tp_methods */
+	0,
 };
 
 static PyObject *dictiter_iternextvalue(dictiterobject *di)
@@ -2191,7 +2196,7 @@ PyTypeObject PyDictIterValue_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&dictiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -2207,6 +2212,8 @@ PyTypeObject PyDictIterValue_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)dictiter_iternextvalue,	/* tp_iternext */
+	dictiter_methods,			/* tp_methods */
+	0,
 };
 
 static PyObject *dictiter_iternextitem(dictiterobject *di)
@@ -2276,7 +2283,7 @@ PyTypeObject PyDictIterItem_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&dictiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -2292,4 +2299,6 @@ PyTypeObject PyDictIterItem_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)dictiter_iternextitem,	/* tp_iternext */
+	dictiter_methods,			/* tp_methods */
+	0,
 };
diff --git a/Objects/enumobject.c b/Objects/enumobject.c
index aac88db..f74acdc 100644
--- a/Objects/enumobject.c
+++ b/Objects/enumobject.c
@@ -239,23 +239,25 @@ PyDoc_STRVAR(reversed_doc,
 "\n"
 "Return a reverse iterator");
 
-static int
+static PyObject *
 reversed_len(reversedobject *ro)
 {
 	int position, seqsize;
 
 	if (ro->seq == NULL)
-		return 0;
+		return PyInt_FromLong(0);
 	seqsize = PySequence_Size(ro->seq);
 	if (seqsize == -1)
-		return -1;
+		return NULL;
 	position = ro->index + 1;
-	return (seqsize < position)  ?  0  :  position;
+	return PyInt_FromLong((seqsize < position)  ?  0  :  position);
 }
 
-static PySequenceMethods reversed_as_sequence = {
-	(inquiry)reversed_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef reversediter_methods[] = {
+	{"_length_cue", (PyCFunction)reversed_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 PyTypeObject PyReversed_Type = {
@@ -272,7 +274,7 @@ PyTypeObject PyReversed_Type = {
 	0,                              /* tp_compare */
 	0,                              /* tp_repr */
 	0,                              /* tp_as_number */
-	&reversed_as_sequence,          /* tp_as_sequence */
+	0,				/* tp_as_sequence */
 	0,                              /* tp_as_mapping */
 	0,                              /* tp_hash */
 	0,                              /* tp_call */
@@ -289,7 +291,7 @@ PyTypeObject PyReversed_Type = {
 	0,                              /* tp_weaklistoffset */
 	PyObject_SelfIter,		/* tp_iter */
 	(iternextfunc)reversed_next,    /* tp_iternext */
-	0,				/* tp_methods */
+	reversediter_methods,		/* tp_methods */
 	0,                              /* tp_members */
 	0,                              /* tp_getset */
 	0,                              /* tp_base */
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index b414cc2..fdee3ca 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -71,7 +71,7 @@ iter_iternext(PyObject *iterator)
 	return NULL;
 }
 
-static int
+static PyObject *
 iter_len(seqiterobject *it)
 {
 	int seqsize, len;
@@ -79,17 +79,19 @@ iter_len(seqiterobject *it)
 	if (it->it_seq) {
 		seqsize = PySequence_Size(it->it_seq);
 		if (seqsize == -1)
-			return -1;
+			return NULL;
 		len = seqsize - it->it_index;
 		if (len >= 0)
-			return len;
+			return PyInt_FromLong(len);
 	}
-	return 0;
+	return PyInt_FromLong(0);
 }
 
-static PySequenceMethods iter_as_sequence = {
-	(inquiry)iter_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef seqiter_methods[] = {
+	{"_length_cue", (PyCFunction)iter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 PyTypeObject PySeqIter_Type = {
@@ -106,7 +108,7 @@ PyTypeObject PySeqIter_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&iter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -122,13 +124,8 @@ PyTypeObject PySeqIter_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)iter_iternext,		/* tp_iternext */
-	0,					/* tp_methods */
+	seqiter_methods,			/* tp_methods */
 	0,					/* tp_members */
-	0,					/* tp_getset */
-	0,					/* tp_base */
-	0,					/* tp_dict */
-	0,					/* tp_descr_get */
-	0,					/* tp_descr_set */
 };
 
 /* -------------------------------------- */
@@ -236,10 +233,4 @@ PyTypeObject PyCallIter_Type = {
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)calliter_iternext,	/* tp_iternext */
 	0,					/* tp_methods */
-	0,					/* tp_members */
-	0,					/* tp_getset */
-	0,					/* tp_base */
-	0,					/* tp_dict */
-	0,					/* tp_descr_get */
-	0,					/* tp_descr_set */
 };
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 3b7358a..1a96361 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -775,7 +775,7 @@ listextend(PyListObject *self, PyObject *b)
 	iternext = *it->ob_type->tp_iternext;
 
 	/* Guess a result list size. */
-	n = PyObject_Size(b);
+	n = _PyObject_LengthCue(b);
 	if (n < 0) {
 		if (!PyErr_ExceptionMatches(PyExc_TypeError)  &&
 		    !PyErr_ExceptionMatches(PyExc_AttributeError)) {
@@ -2764,21 +2764,23 @@ listiter_next(listiterobject *it)
 	return NULL;
 }
 
-static int
+static PyObject *
 listiter_len(listiterobject *it)
 {
 	int len;
 	if (it->it_seq) {
 		len = PyList_GET_SIZE(it->it_seq) - it->it_index;
 		if (len >= 0)
-			return len;
+			return PyInt_FromLong((long)len);
 	}
-	return 0;
+	return PyInt_FromLong(0);
 }
 
-static PySequenceMethods listiter_as_sequence = {
-	(inquiry)listiter_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef listiter_methods[] = {
+	{"_length_cue", (PyCFunction)listiter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 PyTypeObject PyListIter_Type = {
@@ -2795,7 +2797,7 @@ PyTypeObject PyListIter_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&listiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -2811,13 +2813,8 @@ PyTypeObject PyListIter_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)listiter_next,		/* tp_iternext */
-	0,					/* tp_methods */
+	listiter_methods,			/* tp_methods */
 	0,					/* tp_members */
-	0,					/* tp_getset */
-	0,					/* tp_base */
-	0,					/* tp_dict */
-	0,					/* tp_descr_get */
-	0,					/* tp_descr_set */
 };
 
 /*********************** List Reverse Iterator **************************/
diff --git a/Objects/rangeobject.c b/Objects/rangeobject.c
index 8b5650a..3cc5504 100644
--- a/Objects/rangeobject.c
+++ b/Objects/rangeobject.c
@@ -262,17 +262,18 @@ rangeiter_next(rangeiterobject *r)
 	return NULL;
 }
 
-static int
+static PyObject *
 rangeiter_len(rangeiterobject *r)
 {
-	return r->len - r->index;
+	return PyInt_FromLong(r->len - r->index);
 }
 
-static PySequenceMethods rangeiter_as_sequence = {
-	(inquiry)rangeiter_len,		/* sq_length */
-	0,				/* sq_concat */
-};
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyMethodDef rangeiter_methods[] = {
+	{"_length_cue", (PyCFunction)rangeiter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
+};
 
 static PyTypeObject Pyrangeiter_Type = {
 	PyObject_HEAD_INIT(&PyType_Type)
@@ -288,7 +289,7 @@ static PyTypeObject Pyrangeiter_Type = {
 	0,                                      /* tp_compare */
 	0,                                      /* tp_repr */
 	0,                                      /* tp_as_number */
-	&rangeiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,                                      /* tp_as_mapping */
 	0,                                      /* tp_hash */
 	0,                                      /* tp_call */
@@ -304,5 +305,6 @@ static PyTypeObject Pyrangeiter_Type = {
 	0,                                      /* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)rangeiter_next,		/* tp_iternext */
-	0,					/* tp_methods */
+	rangeiter_methods,			/* tp_methods */
+	0,
 };
diff --git a/Objects/setobject.c b/Objects/setobject.c
index c4cd562..29a9184 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -749,17 +749,20 @@ setiter_dealloc(setiterobject *si)
 	PyObject_Del(si);
 }
 
-static int
+static PyObject *
 setiter_len(setiterobject *si)
 {
+	int len = 0;
 	if (si->si_set != NULL && si->si_used == si->si_set->used)
-		return si->len;
-	return 0;
+		len = si->len;
+	return PyInt_FromLong(len);
 }
 
-static PySequenceMethods setiter_as_sequence = {
-	(inquiry)setiter_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef setiter_methods[] = {
+	{"_length_cue", (PyCFunction)setiter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 static PyObject *setiter_iternext(setiterobject *si)
@@ -814,7 +817,7 @@ static PyTypeObject PySetIter_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&setiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -830,6 +833,8 @@ static PyTypeObject PySetIter_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)setiter_iternext,		/* tp_iternext */
+	setiter_methods,			/* tp_methods */
+	0,
 };
 
 static int
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index ea7d753..76e5de3 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -851,17 +851,20 @@ tupleiter_next(tupleiterobject *it)
 	return NULL;
 }
 
-static int
+static PyObject *
 tupleiter_len(tupleiterobject *it)
 {
+	int len = 0;
 	if (it->it_seq)
-		return PyTuple_GET_SIZE(it->it_seq) - it->it_index;
-	return 0;
+		len = PyTuple_GET_SIZE(it->it_seq) - it->it_index;
+	return PyInt_FromLong(len);
 }
 
-static PySequenceMethods tupleiter_as_sequence = {
-	(inquiry)tupleiter_len,		/* sq_length */
-	0,				/* sq_concat */
+PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef tupleiter_methods[] = {
+	{"_length_cue", (PyCFunction)tupleiter_len, METH_NOARGS, length_cue_doc},
+ 	{NULL,		NULL}		/* sentinel */
 };
 
 PyTypeObject PyTupleIter_Type = {
@@ -878,7 +881,7 @@ PyTypeObject PyTupleIter_Type = {
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
-	&tupleiter_as_sequence,			/* tp_as_sequence */
+	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
@@ -894,4 +897,6 @@ PyTypeObject PyTupleIter_Type = {
 	0,					/* tp_weaklistoffset */
 	PyObject_SelfIter,			/* tp_iter */
 	(iternextfunc)tupleiter_next,		/* tp_iternext */
+	tupleiter_methods,			/* tp_methods */
+	0,
 };