diff options
Diffstat (limited to 'Modules/collectionsmodule.c')
| -rw-r--r-- | Modules/collectionsmodule.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/Modules/collectionsmodule.c b/Modules/collectionsmodule.c index d60ede1..0e0b2d6 100644 --- a/Modules/collectionsmodule.c +++ b/Modules/collectionsmodule.c @@ -247,14 +247,21 @@ PyDoc_STRVAR(extendleft_doc, static PyObject * deque_rotate(dequeobject *deque, PyObject *args) { - int i, n; + int i, n=1, len=deque->len, halflen=(len+1)>>1; PyObject *item, *rv; - if (!PyArg_ParseTuple(args, "i:rotate", &n)) + if (!PyArg_ParseTuple(args, "|i:rotate", &n)) return NULL; - if (n == 0 || deque->len == 0) + if (len == 0) Py_RETURN_NONE; + if (n > halflen || n < -halflen) { + n %= len; + if (n > halflen) + n -= len; + else if (n < -halflen) + n += len; + } for (i=0 ; i<n ; i++) { item = deque_pop(deque, NULL); @@ -280,7 +287,7 @@ deque_rotate(dequeobject *deque, PyObject *args) } PyDoc_STRVAR(rotate_doc, -"Rotate the deque n steps to the right. If n is negative, rotates left."); +"Rotate the deque n steps to the right (default n=1). If n is negative, rotates left."); static int deque_len(dequeobject *deque) |