JpnForPhp\Transliterator\Romaji::transliterateSokuon PHP Метод

    protected function transliterateSokuon($str, $parameters)
    {
        if ($parameters['default']) {
            $str = preg_replace('/[っッ](.)/u', '${1}${1}', $str);
        }
        // As per Hepburn system ch > tch
        // (http://en.wikipedia.org/wiki/Hepburn_romanization#Double_consonants)
        if ($parameters['hepburn']) {
            $str = str_replace('cch', 'tch', $str);
        }
        return $str;
    }