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#ifndef MOZC_PREDICTION_PREDICTOR_INTERFACE_H_
#define MOZC_PREDICTION_PREDICTOR_INTERFACE_H_

#include <string>

#include "base/port_string.h"

namespace mozc {

class ConversionRequest;
class Segments;

class PredictorInterface {
 public:
  virtual ~PredictorInterface() = default;

  // Returns suggestions.
  // You may need to change the behavior according to the
  // Segments::request_type flag
  // SUGGESTION: automatic suggestions
  // PREDICTION: invoked only when user pushes "tab" key.
  // less aggressive than SUGGESTION mode.
  virtual bool PredictForRequest(const ConversionRequest &request,
                                 Segments *segments) const = 0;

  // Hook(s) for all mutable operations.
  virtual void Finish(const ConversionRequest &request, Segments *segments) {}

  // Reverts the last Finish operation.
  virtual void Revert(Segments *segments) {}

  // Clears all history data of UserHistoryPredictor.
  virtual bool ClearAllHistory() { return true; }

  // Clears unused history data of UserHistoryPredictor.
  virtual bool ClearUnusedHistory() { return true; }

  // Clears a specific history data of UserHistoryPredictor.
  virtual bool ClearHistoryEntry(const string &key,
                                 const string &value) { return true; }

  // Syncs user history to local disk.
  virtual bool Sync() { return true; }

  // Reloads user history data from local disk.
  virtual bool Reload() { return true; }

  // Waits for syncer thread to complete.
  virtual bool Wait() { return true; }

  virtual const string &GetPredictorName() const = 0;

 protected:
  // Disable the construction.
  PredictorInterface() = default;
};

}  // namespace mozc

#endif  // MOZC_PREDICTION_PREDICTOR_INTERFACE_H_