Make member variables const.

                const std::vector<int> *custom_rid_rank)

      : mapping_output_file_path_(mapping_output_file_path),

        mapping_output_format_(mapping_output_format),

        cell_barcode_length_(cell_barcode_length) {

        cell_barcode_length_(cell_barcode_length),

        custom_rid_rank_(custom_rid_rank != nullptr ? *custom_rid_rank

                                                    : std::vector<int>()) {

    if (barcode_translate_table_file_path != nullptr) {

      barcode_translator_.SetTranslateTable(*barcode_translate_table_file_path);

    }

    if (custom_rid_rank != nullptr) {

      custom_rid_rank_ = *custom_rid_rank;

    }

    mapping_output_file_ = fopen(mapping_output_file_path_.c_str(), "w");

    assert(mapping_output_file_ != nullptr);

  }

    return sequence;

  }

  std::string mapping_output_file_path_;

  const std::string mapping_output_file_path_;

  // TODO(Haowen): use this variable to decide output in BED or TagAlign. It

  // should be removed later.

  MappingOutputFormat mapping_output_format_ = MAPPINGFORMAT_BED;

  uint32_t cell_barcode_length_ = 16;

  const MappingOutputFormat mapping_output_format_;

  const uint32_t cell_barcode_length_;

  FILE *mapping_output_file_ = nullptr;

  BarcodeTranslator barcode_translator_;

  // for pairs

  std::vector<int> custom_rid_rank_;

  const std::vector<int> custom_rid_rank_;

};

// Specialization for BED format.