Networking\InitCmsBundle\Helper\LanguageSwitcherHelper::getUrlencodedPrefix PHP Method

    protected function getUrlencodedPrefix($string, $prefix)
    {
        if (0 !== strpos(rawurldecode($string), $prefix)) {
            return false;
        }
        $len = strlen($prefix);
        if (preg_match("#^(%[[:xdigit:]]{2}|.){{$len}}#", $string, $match)) {
            return $match[0];
        }
        return false;
    }