BITCOUNT command

txredis/client.py

@@ -267,6 +267,22 @@ def setbit(self, key, offset, value):
         self._send('SETBIT', key, offset, value)
         return self.getResponse()
 
+    def bitcount(self, key, start=None, end=None):
+        """
+        Count the number of set bits (population counting) in a string.
+
+        @param key: The Redis key to get bit count from.
+        @param start: Optional starting index for bytes to scan (inclusive)
+        @param end: Optional ending index for bytes to scan (inclusive). End index is
+        required when start is given.
+        """
+        start_end = []
+        if start is not None:
+            start_end.append(start)
+            start_end.append(end)
+        self._send('BITCOUNT', key, *start_end)
+        return self.getResponse()
+
     # Commands operating on the key space
     def keys(self, pattern):
         """

txredis/tests/test_client.py

@@ -651,6 +651,30 @@ def test_getbit(self):
         self.assertEqual(a, 1)
 
 
+    @defer.inlineCallbacks
+    def test_bitcount(self):
+        r = self.redis
+        # TODO tearDown or setUp should flushdb?
+        yield r.delete('bittest')
+
+        yield r.setbit('bittest', 10, 1)
+        yield r.setbit('bittest', 25, 1)
+        yield r.setbit('bittest', 3, 1)
+        ct = yield r.bitcount('bittest')
+        self.assertEqual(ct, 3)
+
+    @defer.inlineCallbacks
+    def test_bitcount_with_start_and_end(self):
+        r = self.redis
+        yield r.delete('bittest')
+
+        yield r.setbit('bittest', 10, 1)
+        yield r.setbit('bittest', 25, 1)
+        yield r.setbit('bittest', 3, 1)
+        ct = yield r.bitcount('bittest', 1, 2)
+        self.assertEqual(ct, 1)
+
+
 class ListsCommandsTestCase(CommandsBaseTestCase):
     """Test commands that operate on lists.
     """