text: #ifndef LIGHTGBM_DATASET_LOADER_H_
  #define LIGHTGBM_DATASET_LOADER_H_
  
  #include <LightGBM/dataset.h>
  
  namespace LightGBM {
  
  class DatasetLoader {
  public:
  
    DatasetLoader(const IOConfig& io_config, const PredictFunction& predict_fun);
  
    ~DatasetLoader();
  
    void SetHeader(const char* filename);
  
    Dataset* LoadFromFile(const char* filename, int rank, int num_machines);
  
    Dataset* LoadFromFile(const char* filename) {
      return LoadFromFile(filename, 0, 1);
    }
  
    Dataset* LoadFromFileAlignWithOtherDataset(const char* filename, const Dataset* train_data);
  
    Dataset* LoadFromBinFile(const char* bin_filename, int rank, int num_machines);
  
    Dataset* CostructFromSampleData(std::vector<std::vector<double>>& sample_values, size_t total_sample_size, data_size_t num_data);
  
    /*! \brief Disable copy */
    DatasetLoader& operator=(const DatasetLoader&) = delete;
    /*! \brief Disable copy */
    DatasetLoader(const DatasetLoader&) = delete;
  
  private:
    void CheckDataset(const Dataset* dataset);
  
    std::vector<std::string> LoadTextDataToMemory(const char* filename, const Metadata& metadata, int rank, int num_machines, int* num_global_data, std::vector<data_size_t>* used_data_indices);
  
    std::vector<std::string> SampleTextDataFromMemory(const std::vector<std::string>& data);
  
    std::vector<std::string> SampleTextDataFromFile(const char* filename, const Metadata& metadata, int rank, int num_machines, int* num_global_data, std::vector<data_size_t>* used_data_indices);
  
    void ConstructBinMappersFromTextData(int rank, int num_machines, const std::vector<std::string>& sample_data, const Parser* parser, Dataset* dataset);
  
    /*! \brief Extract local features from memory */
    void ExtractFeaturesFromMemory(std::vector<std::string>& text_data, const Parser* parser, Dataset* dataset);
  
    /*! \brief Extract local features from file */
    void ExtractFeaturesFromFile(const char* filename, const Parser* parser, const std::vector<data_size_t>& used_data_indices, Dataset* dataset);
  
    /*! \brief Check can load from binary file */
    bool CheckCanLoadFromBin(const char* filename);
  
    const IOConfig& io_config_;
    /*! \brief Random generator*/
    Random random_;
    /*! \brief prediction function for initial model */
    const PredictFunction& predict_fun_;
    /*! \brief index of label column */
    int label_idx_ = 0;
    /*! \brief index of weight column */
    int weight_idx_ = NO_SPECIFIC;
    /*! \brief index of group column */
    int group_idx_ = NO_SPECIFIC;
    /*! \brief Mapper from real feature index to used index*/
    std::unordered_set<int> ignore_features_;
    /*! \brief store feature names */
    std::vector<std::string> feature_names_;
  
  };
  
  }
  
  #endif // LIGHTGBM_DATASET_LOADER_H_