trellis.h

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#ifndef META_SEQUENCE_TRELLIS_H_
#define META_SEQUENCE_TRELLIS_H_

#include <vector>
#include <unordered_map>

#include "meta.h"
#include "sequence/observation.h"
#include "util/dense_matrix.h"

namespace meta
{
namespace sequence
{

class trellis
{
  protected:
    util::dense_matrix<double> trellis_;

  public:
    trellis(uint64_t size, uint64_t labels);

    uint64_t size() const;

    void probability(uint64_t idx, const label_id& tag, double prob);

    double probability(uint64_t idx, const label_id& tag) const;
};

class forward_trellis : public trellis
{
  private:
    std::vector<double> normalizers_;

  public:
    forward_trellis(uint64_t size, uint64_t labels);

    double normalizer(uint64_t idx) const;

    void normalize(uint64_t idx);
};

class viterbi_trellis : public trellis
{
  private:
    util::dense_matrix<label_id> paths_;

  public:
    viterbi_trellis(uint64_t size, uint64_t labels);

    void previous_tag(uint64_t idx, const label_id& current,
                      const label_id& previous);

    const label_id& previous_tag(uint64_t idx, const label_id& current) const;
};
}
}
#endif