private static function _init_detab()
    {
        if (function_exists(self::$utf8_strlen)) {
            return;
        }
        self::$utf8_strlen = create_function('$text', 'return preg_match_all(
			"/[\\\\x00-\\\\xBF]|[\\\\xC0-\\\\xFF][\\\\x80-\\\\xBF]*/",
			$text, $m);');
    }