private static function _encodeConstants(\ReflectionClass $cls)
    {
        $result    = "constants : {";
        $constants = $cls->getConstants();

        $tmpArray = array();
        if (!empty($constants)) {
            foreach ($constants as $key => $value) {
                $tmpArray[] = "$key: " . self::encode($value);
            }

            $result .= implode(', ', $tmpArray);
        }

        return $result . "}";
    }