public function registerClasses($classes, $merge = true)
    {
        if (DIRECTORY_SEPARATOR === '\\') {
            foreach ($classes as $key => $path) {
                $classes[$key] = strtr($path, '\\', '/');
            }
        }

        $this->_classes = $merge ? array_merge($this->_classes, $classes) : $classes;

        return $this;
    }