SF bug 433228: repr(list) woes when len(list) big.
Gave Python linear-time repr() implementations for dicts, lists, strings.
This means, e.g., that repr(range(50000)) is no longer 50x slower than
pprint.pprint() in 2.2 <wink>.
I don't consider this a bugfix candidate, as it's a performance boost.
Added _PyString_Join() to the internal string API. If we want that in the
public API, fine, but then it requires runtime error checks instead of
asserts.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index e595c85..6fb3145 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -246,26 +246,68 @@
static PyObject *
list_repr(PyListObject *v)
{
- PyObject *s, *comma;
int i;
+ PyObject *s, *temp;
+ PyObject *pieces = NULL, *result = NULL;
i = Py_ReprEnter((PyObject*)v);
if (i != 0) {
- if (i > 0)
- return PyString_FromString("[...]");
- return NULL;
+ return i > 0 ? PyString_FromString("[...]") : NULL;
}
+
+ if (v->ob_size == 0) {
+ result = PyString_FromString("[]");
+ goto Done;
+ }
+
+ pieces = PyList_New(0);
+ if (pieces == NULL)
+ goto Done;
+
+ /* Do repr() on each element. Note that this may mutate the list,
+ so must refetch the list size on each iteration. */
+ for (i = 0; i < v->ob_size; ++i) {
+ int status;
+ s = PyObject_Repr(v->ob_item[i]);
+ if (s == NULL)
+ goto Done;
+ status = PyList_Append(pieces, s);
+ Py_DECREF(s); /* append created a new ref */
+ if (status < 0)
+ goto Done;
+ }
+
+ /* Add "[]" decorations to the first and last items. */
+ assert(PyList_GET_SIZE(pieces) > 0);
s = PyString_FromString("[");
- comma = PyString_FromString(", ");
- for (i = 0; i < v->ob_size && s != NULL; i++) {
- if (i > 0)
- PyString_Concat(&s, comma);
- PyString_ConcatAndDel(&s, PyObject_Repr(v->ob_item[i]));
- }
- Py_XDECREF(comma);
- PyString_ConcatAndDel(&s, PyString_FromString("]"));
+ if (s == NULL)
+ goto Done;
+ temp = PyList_GET_ITEM(pieces, 0);
+ PyString_ConcatAndDel(&s, temp);
+ PyList_SET_ITEM(pieces, 0, s);
+ if (s == NULL)
+ goto Done;
+
+ s = PyString_FromString("]");
+ if (s == NULL)
+ goto Done;
+ temp = PyList_GET_ITEM(pieces, PyList_GET_SIZE(pieces) - 1);
+ PyString_ConcatAndDel(&temp, s);
+ PyList_SET_ITEM(pieces, PyList_GET_SIZE(pieces) - 1, temp);
+ if (temp == NULL)
+ goto Done;
+
+ /* Paste them all together with ", " between. */
+ s = PyString_FromString(", ");
+ if (s == NULL)
+ goto Done;
+ result = _PyString_Join(s, pieces);
+ Py_DECREF(s);
+
+Done:
+ Py_XDECREF(pieces);
Py_ReprLeave((PyObject *)v);
- return s;
+ return result;
}
static int