Add count() method to collections.deque().
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 978bd9a..5d3fc6b 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -504,6 +504,46 @@
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 @@
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,