bleu.hpp

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#ifndef MLPACK_CORE_METRICS_BLEU_HPP
#define MLPACK_CORE_METRICS_BLEU_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace metric {

template <typename ElemType = float,
          typename PrecisionType = std::vector<ElemType>
>
class BLEU
{
 public:
  BLEU(const size_t maxOrder = 4);

  template <typename ReferenceCorpusType, typename TranslationCorpusType>
  ElemType Evaluate(const ReferenceCorpusType& referenceCorpus,
                    const TranslationCorpusType& translationCorpus,
                    const bool smooth = false);

  template<typename Archive>
  void serialize(Archive& ar, const uint32_t version);

  size_t MaxOrder() const { return maxOrder; }
  size_t& MaxOrder() { return maxOrder; }

  ElemType BLEUScore() const { return bleuScore; }

  ElemType BrevityPenalty() const { return brevityPenalty; }

  size_t TranslationLength() const { return translationLength; }

  size_t ReferenceLength() const { return referenceLength; }

  ElemType Ratio() const { return ratio; }

  PrecisionType const& Precisions() const { return precisions; }

 private:
  template <typename WordVector>
  std::map<WordVector, size_t> GetNGrams(const WordVector& segment);

  size_t maxOrder;

  ElemType bleuScore;

  ElemType brevityPenalty;

  size_t translationLength;

  size_t referenceLength;

  ElemType ratio;

  PrecisionType precisions;
};

} // namespace metric
} // namespace mlpack

// Include implementation.
#include "bleu_impl.hpp"

#endif