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Add count() method to collections.deque().

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This commit is contained in:
Raymond Hettinger 2010-04-03 18:10:37 +00:00
parent 30583e3f38
commit 5f516edd77
4 changed files with 56 additions and 1 deletions
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42
Modules/_collectionsmodule.c
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@ -504,6 +504,46 @@ deque_reverse(dequeobject *deque, PyObject *unused)
PyDoc_STRVAR(reverse_doc,
"D.reverse() -- reverse *IN PLACE*");
static PyObject *
deque_count(dequeobject *deque, PyObject *v)
{
block *leftblock = deque->leftblock;
Py_ssize_t leftindex = deque->leftindex;
Py_ssize_t n = (deque->len);
Py_ssize_t i;
Py_ssize_t count = 0;
PyObject *item;
long start_state = deque->state;
int cmp;
for (i=0 ; i<n ; i++) {
item = leftblock->data[leftindex];
cmp = PyObject_RichCompareBool(item, v, Py_EQ);
if (cmp > 0)
count++;
else if (cmp < 0)
return NULL;
if (start_state != deque->state) {
PyErr_SetString(PyExc_RuntimeError,
"deque mutated during iteration");
return NULL;
}
/* Advance left block/index pair */
leftindex++;
if (leftindex == BLOCKLEN) {
assert (leftblock->rightlink != NULL);
leftblock = leftblock->rightlink;
leftindex = 0;
}
}
return PyInt_FromSsize_t(count);
}
PyDoc_STRVAR(count_doc,
"D.count(value) -> integer -- return number of occurrences of value");
static Py_ssize_t
deque_len(dequeobject *deque)
{
@ -991,6 +1031,8 @@ static PyMethodDef deque_methods[] = {
METH_NOARGS, clear_doc},
{"__copy__", (PyCFunction)deque_copy,
METH_NOARGS, copy_doc},
{"count", (PyCFunction)deque_count,
METH_O, count_doc},
{"extend", (PyCFunction)deque_extend,
METH_O, extend_doc},
{"extendleft", (PyCFunction)deque_extendleft,