// DefaultDatasetMerger.h

#ifndef dset__DefaultDatasetMerger_H
#define dset__DefaultDatasetMerger_H

// David Adams
// April 2004
//
// This dataset merger merges datasets into the same type using
// their merge method.
//
// All compound datasets returned as results are stored in
// the current default dataset repository.
//
// The merger manages the datasets it returns in its result.
// A call to result deletes the dataset returned in the
// previous call if it has changed.

#include "dataset_util/Text.h"
#include "dataset_split/DatasetMerger.h"

namespace dset {

class Dataset;

class DefaultDatasetMerger : public DatasetMerger {

private:  // data

  std::string m_dir;
  int m_err;
  DatasetList m_dsts;
  Dataset* m_pdst;
  Dataset* m_pdstres;
  DatasetMergeResult* m_pres;
  bool m_open;

private:  // No copy or assignment

  // Copy.
  DefaultDatasetMerger(const DefaultDatasetMerger& rhs);

  // Assignment.
  DefaultDatasetMerger& operator=(const DefaultDatasetMerger& rhs);

public:  // constructors and destructor.

  // Constructor.
  // Argument is the working directory.
  DefaultDatasetMerger(std::string dir);

  // Destructor.
  ~DefaultDatasetMerger();

public:  // inherited functions

  // Validity.
  bool is_valid() const;

  // Closed.
  bool is_open() const;

  // Append a dataset.
  int append(const Dataset& dst);

  // Return the result.
  // This should not be blocking--if the result will require a long
  // time to calculate, then this method should quickly return a
  // (consistent) partial result.
  DatasetMergeResult result();

  // Close.
  int close();

  // Output stream.
  std::ostream& ostr(std::ostream& str) const;

public:  // local functions

  // Set error and return error code.
  int set_error(int err);

  // Return the error code.
  int error() const;

};

}  // end namespace dset

#endif