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#ifndef MERT_BLEU_SCORER_H_
#define MERT_BLEU_SCORER_H_
#include <ostream>
#include <string>
#include <vector>
#include "Types.h"
#include "ScoreData.h"
#include "StatisticsBasedScorer.h"
#include "ScopedVector.h"
namespace MosesTuning
{
const int kBleuNgramOrder = 4;
class NgramCounts;
class Reference;
/**
* Bleu scoring
*/
class BleuScorer: public StatisticsBasedScorer
{
public:
enum ReferenceLengthType {
AVERAGE,
CLOSEST,
SHORTEST
};
explicit BleuScorer(const std::string& config = "");
~BleuScorer();
static std::vector<float> ScoreNbestList(const std::string& scoreFile, const std::string& featureFile);
static float sentenceLevelBleuPlusOne(const std::vector<float>& stats);
virtual void setReferenceFiles(const std::vector<std::string>& referenceFiles);
virtual void prepareStats(std::size_t sid, const std::string& text, ScoreStats& entry);
virtual statscore_t calculateScore(const std::vector<int>& comps) const;
virtual std::size_t NumberOfScores() const { return 2 * kBleuNgramOrder + 1; }
int CalcReferenceLength(std::size_t sentence_id, std::size_t length);
ReferenceLengthType GetReferenceLengthType() const { return m_ref_length_type; }
void SetReferenceLengthType(ReferenceLengthType type) { m_ref_length_type = type; }
const std::vector<Reference*>& GetReferences() const { return m_references.get(); }
/**
* Count the ngrams of each type, up to the given length in the input line.
*/
std::size_t CountNgrams(const std::string& line, NgramCounts& counts, unsigned int n, bool is_testing=false);
void DumpCounts(std::ostream* os, const NgramCounts& counts) const;
bool OpenReference(const char* filename, std::size_t file_id);
// NOTE: this function is used for unit testing.
bool OpenReferenceStream(std::istream* is, std::size_t file_id);
private:
ReferenceLengthType m_ref_length_type;
// reference translations.
ScopedVector<Reference> m_references;
// no copying allowed
BleuScorer(const BleuScorer&);
BleuScorer& operator=(const BleuScorer&);
};
/** Computes sentence-level BLEU+1 score.
* This function is used in PRO.
*/
float sentenceLevelBleuPlusOne(const std::vector<float>& stats);
/** Computes sentence-level BLEU score given a background corpus.
* This function is used in batch MIRA.
*/
float sentenceLevelBackgroundBleu(const std::vector<float>& sent, const std::vector<float>& bg);
/**
* Computes plain old BLEU from a vector of stats
*/
float unsmoothedBleu(const std::vector<float>& stats);
}
#endif // MERT_BLEU_SCORER_H_
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