ManaPHP\Http\Filter::_filter_length PHP Метод

    protected function _filter_length($value, $parameters)
    {
        if (function_exists('mb_strlen')) {
            $length = mb_strlen($value);
        } else {
            $length = strlen($value);
        }
        if ($length >= $parameters[0] && $length <= $parameters[1]) {
            return $value;
        } else {
            return null;
        }
    }