absolute_discount.h

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#ifndef META_ABSOLUTE_DISCOUNT_H_
#define META_ABSOLUTE_DISCOUNT_H_

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

namespace meta
{
namespace index
{

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

    absolute_discount(double delta = 0.7);

    double smoothed_prob(const score_data& sd) const override;

    double doc_constant(const score_data& sd) const override;

  private:
    const double delta_;
};

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