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Make deque.rotate() smarter. Beef-up related tests.

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This commit is contained in:
Raymond Hettinger 2004-02-08 04:05:26 +00:00
parent 3b6d025d9b
commit ee33b27ef0
2 changed files with 54 additions and 13 deletions
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15
Modules/collectionsmodule.c
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@ -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)