Add count() method to collections.deque().
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 5a6f0de..f4ba51a 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -358,6 +358,12 @@
Remove all elements from the deque leaving it with length 0.
+ .. method:: count(x)
+
+ Count the number of deque elements equal to *x*.
+
+ .. versionadded:: 2.7
+
.. method:: extend(iterable)
Extend the right side of the deque by appending elements from the iterable
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 7de016f..3021f63 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -113,6 +113,13 @@
d = deque('abc')
d.maxlen = 10
+ def test_count(self):
+ for s in ('', 'abracadabra', 'simsalabim'*500+'abc'):
+ s = list(s)
+ d = deque(s)
+ for letter in 'abcdefghijklmnopqrstuvwxyz':
+ self.assertEqual(s.count(letter), d.count(letter), (s, d, letter))
+
def test_comparisons(self):
d = deque('xabc'); d.popleft()
for e in [d, deque('abc'), deque('ab'), deque(), list(d)]:
diff --git a/Misc/NEWS b/Misc/NEWS
index e942fb7..5001145 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1223,7 +1223,7 @@
Library
-------
-- Add a reverse() method to collections.deque().
+- Add count() and reverse() methods to collections.deque().
- Fix variations of extending deques: d.extend(d) d.extendleft(d) d+=d
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,