Improve algorithm for set.difference when the input is not a set.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 36072ce..4fbb645 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -357,49 +357,6 @@
}
static PyObject *
-set_difference(PySetObject *so, PyObject *other)
-{
- PySetObject *result, *otherset=NULL;
- PyObject *otherdata, *tgtdata;
- PyObject *key, *value;
- int pos = 0;
-
- result = (PySetObject *)make_new_set(so->ob_type, NULL);
- if (result == NULL)
- return NULL;
- tgtdata = result->data;
-
- if (PyDict_Check(other))
- otherdata = other;
- else if (PyAnySet_Check(other))
- otherdata = ((PySetObject *)other)->data;
- else {
- otherset = (PySetObject *)make_new_set(so->ob_type, other);
- if (otherset == NULL) {
- Py_DECREF(result);
- return NULL;
- }
- otherdata = otherset->data;
- }
-
- while (PyDict_Next(so->data, &pos, &key, &value)) {
- if (!PyDict_Contains(otherdata, key)) {
- if (PyDict_SetItem(tgtdata, key, Py_True) == -1) {
- Py_XDECREF(otherset);
- return NULL;
- }
- }
- }
- Py_XDECREF(otherset);
- return (PyObject *)result;
-}
-
-PyDoc_STRVAR(difference_doc,
-"Return the difference of two sets as a new set.\n\
-\n\
-(i.e. all elements that are in this set but not the other.)");
-
-static PyObject *
set_difference_update(PySetObject *so, PyObject *other)
{
PyObject *item, *tgtdata, *it;
@@ -431,6 +388,49 @@
"Remove all elements of another set from this set.");
static PyObject *
+set_difference(PySetObject *so, PyObject *other)
+{
+ PyObject *result, *tmp;
+ PyObject *otherdata, *tgtdata;
+ PyObject *key, *value;
+ int pos = 0;
+
+ if (PyDict_Check(other))
+ otherdata = other;
+ else if (PyAnySet_Check(other))
+ otherdata = ((PySetObject *)other)->data;
+ else {
+ result = set_copy(so);
+ if (result == NULL)
+ return result;
+ tmp = set_difference_update((PySetObject *)result, other);
+ if (tmp != NULL) {
+ Py_DECREF(tmp);
+ return result;
+ }
+ Py_DECREF(result);
+ return NULL;
+ }
+
+ result = make_new_set(so->ob_type, NULL);
+ if (result == NULL)
+ return NULL;
+ tgtdata = ((PySetObject *)result)->data;
+
+ while (PyDict_Next(so->data, &pos, &key, &value)) {
+ if (!PyDict_Contains(otherdata, key)) {
+ if (PyDict_SetItem(tgtdata, key, Py_True) == -1)
+ return NULL;
+ }
+ }
+ return result;
+}
+
+PyDoc_STRVAR(difference_doc,
+"Return the difference of two sets as a new set.\n\
+\n\
+(i.e. all elements that are in this set but not the other.)");
+static PyObject *
set_sub(PySetObject *so, PyObject *other)
{
if (!PyAnySet_Check(so) || !PyAnySet_Check(other)) {