private function inferArrayElementTypeFromDesc($desc)
    {
        if (preg_match_all('#array\s+of\s+``([^`]+)``#', $desc, $matches)) {
            $types = array();
            foreach ($matches[1] as $m) {
                $types[] = $m.'[]';
            }

            return implode('|', $types);
        }

        return null;
    }