bitpos command implementation

redis/client.py

@@ -293,10 +293,10 @@ class StrictRedis(object):
             bool
         ),
         string_keys_to_dict(
-            'BITCOUNT DECRBY DEL GETBIT HDEL HLEN INCRBY LINSERT LLEN LPUSHX '
-            'PFADD PFCOUNT RPUSHX SADD SCARD SDIFFSTORE SETBIT SETRANGE '
-            'SINTERSTORE SREM STRLEN SUNIONSTORE ZADD ZCARD ZLEXCOUNT ZREM '
-            'ZREMRANGEBYLEX ZREMRANGEBYRANK ZREMRANGEBYSCORE',
+            'BITCOUNT BITPOS DECRBY DEL GETBIT HDEL HLEN INCRBY LINSERT LLEN '
+            'LPUSHX PFADD PFCOUNT RPUSHX SADD SCARD SDIFFSTORE SETBIT '
+            'SETRANGE SINTERSTORE SREM STRLEN SUNIONSTORE ZADD ZCARD '
+            'ZLEXCOUNT ZREM ZREMRANGEBYLEX ZREMRANGEBYRANK ZREMRANGEBYSCORE',
             int
         ),
         string_keys_to_dict('INCRBYFLOAT HINCRBYFLOAT', float),
@@ -782,6 +782,26 @@ def bitop(self, operation, dest, *keys):
         """
         return self.execute_command('BITOP', operation, dest, *keys)
 
+    def bitpos(self, key, bit, start=None, end=None):
+        """
+        Return the position of the first bit set to 1 or 0 in a string.
+        ``start`` and ``end`` difines search range. The range is interpreted
+        as a range of bytes and not a range of bits, so start=0 and end=2
+        means to look at the first three bytes.
+        """
+        if bit not in (0, 1):
+            raise RedisError('bit must be 0 or 1')
+        params = [key, bit]
+
+        start is not None and params.append(start)
+
+        if start is not None and end is not None:
+            params.append(end)
+        elif start is None and end is not None:
+            raise RedisError("start argument is not set, "
+                             "when end is specified")
+        return self.execute_command('BITPOS', *params)
+
     def decr(self, name, amount=1):
         """
         Decrements the value of ``key`` by ``amount``.  If no key exists,

tests/test_commands.py

@@ -230,6 +230,28 @@ def test_bitop_string_operands(self, r):
         assert int(binascii.hexlify(r['res2']), 16) == 0x0102FFFF
         assert int(binascii.hexlify(r['res3']), 16) == 0x000000FF
 
+    @skip_if_server_version_lt('2.8.7')
+    def test_bitpos(self, r):
+        key = 'key:bitpos'
+        r.set(key, '\xff\xf0\x00')
+        assert r.bitpos(key, 0) == 12
+        assert r.bitpos(key, 0, 2, -1) == 16
+        assert r.bitpos(key, 0, -2, -1) == 12
+        r.set(key, '\x00\xff\xf0')
+        assert r.bitpos(key, 1, 0) == 8
+        assert r.bitpos(key, 1, 1) == 8
+        r.set(key, '\x00\x00\x00')
+        assert r.bitpos(key, 1) == -1
+
+    @skip_if_server_version_lt('2.8.7')
+    def test_bitpos_wrong_arguments(self, r):
+        key = 'key:bitpos:wrong:args'
+        r.set(key, '\xff\xf0\x00')
+        with pytest.raises(exceptions.RedisError):
+            r.bitpos(key, 0, end=1) == 12
+        with pytest.raises(exceptions.RedisError):
+            r.bitpos(key, 7) == 12
+
     def test_decr(self, r):
         assert r.decr('a') == -1
         assert r['a'] == b('-1')