private function indentationModeSwitch(string $line): int
  {
    $mode = 0;

    if (substr($line, 0, 5)=='case ')
    {
      $mode |= self::C_INDENT_INCREMENT_AFTER;
    }

    if (substr($line, 0, 8)=='default:')
    {
      $this->defaultLevel[] = 0;

      $mode |= self::C_INDENT_INCREMENT_AFTER;
    }

    if (substr($line, 0, 6)=='break;')
    {
      $mode |= self::C_INDENT_DECREMENT_AFTER;
    }

    return $mode;
  }