jelinek_mercer.h

Go to the documentation of this file.

#ifndef META_JELINEK_MERCER_H_
#define META_JELINEK_MERCER_H_

#include "index/ranker/lm_ranker.h"
#include "index/ranker/ranker_factory.h"

namespace meta
{
namespace index
{

class jelinek_mercer : public language_model_ranker
{
  public:
    const static std::string id;

    const static constexpr double default_lambda = 0.7;

    jelinek_mercer(double lambda = default_lambda);

    double smoothed_prob(const score_data& sd) const override;

    double doc_constant(const score_data& sd) const override;

  private:
    const double lambda_;
};

template <>
std::unique_ptr<ranker> make_ranker<jelinek_mercer>(const cpptoml::table&);
}
}

#endif