protected function _applySort($url)
    {
        if (!$this->_sortEnabled) {
            return $url;
        }

        if (!empty($this->request->getQuery('s'))) {
            $url['?']['s'] = $this->request->getQuery('s');
        }

        if (!empty($this->request->getQuery('d'))) {
            $url['?']['d'] = $this->request->getQuery('d');
        }

        return $url;
    }