Rack::swap PHP Method

    public static function swap($target, $name, $file = null)
    {
        if (!self::$constructed) {
            if (array_key_exists($target, self::$middleware)) {
                $keys = array_keys(self::$middleware);
                $length = count($keys);
                $middleware = array();
                for ($i = 0; $i < $length; $i++) {
                    if ($keys[$i] == $target) {
                        $middleware[$name] = true;
                    } else {
                        $middleware[$keys[$i]] =& self::$middleware[$keys[$i]];
                    }
                }
                self::$middleware = $middleware;
                self::require_file($file);
                return false;
            }
        }
        return false;
    }