protected function getNormalizedOptionNameMap() {

    if (!isset($this->normalized_option_name_map)) {
      $this->normalized_option_name_map = array();

      foreach ($this->argument_spec_data['options'] as $argument_spec) {
        $long_name = $argument_spec['long'];
        if (strlen($long_name)) {
          $this->normalized_option_name_map[$long_name] = $long_name;
        } else {
          $long_name = null;
        }

        $short_name = $argument_spec['short'];
        if (strlen($short_name)) {
          $this->normalized_option_name_map[$short_name] = (strlen($long_name) ? $long_name : $short_name);
        }
      }
    }

    return $this->normalized_option_name_map;
  }