decoder.h

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#ifndef __ZGEN_SHIFTREDUCE_DECODER_H__
#define __ZGEN_SHIFTREDUCE_DECODER_H__

#include <iostream>
#include "knowledge/postag_constrain.h"
#include "shiftreduce/option.h"
#include "shiftreduce/types/state.h"
#include "shiftreduce/types/internal_types.h"
#include "shiftreduce/model/model.h"
#include "shiftreduce/decode/decode_context.h"

namespace ZGen {
namespace ShiftReduce {

class Decoder {
public:
  Decoder(const option_t& opts,
      DecodeContext* ctx,
      Model* model,
      const Knowledge::PostagConstrain* constrain);
  ~Decoder();
public:
  typedef std::pair<const StateItem*, const StateItem*> decode_result_t;

  decode_result_t decode(const dependency_t* input,
      const action_sequence_t& gold_actions);

protected:
  virtual void get_possible_actions(const StateItem& item) = 0;

  virtual void config_input(const dependency_t* input) = 0;

  void get_possible_shift_actions(const StateItem& item,
      int index, word_t word, postag_t postag);

  const option_t& opts;
  Model* model;
  DecodeContext* ctx;

  action_sequence_t possible_actions;
  packed_score_t packed_score;
  scored_transition_t candidate_transitions[kMaxBeamSize];
  const Knowledge::PostagConstrain* constraint;
private:
  void score_possible_actions(const StateItem& item);

  int extend_candidate_transition(const scored_transition_t& trans,
      int current_beam_size);

  void clear_candidate_transition();

  void transit(const StateItem& from, const action_t& act,
      floatval_t score, StateItem* to);

  const StateItem* search_correct_state(const action_t& act,
      const StateItem* previous_correct_state,
      StateItem* begin, StateItem* end);

  const StateItem* search_best_state(const StateItem* begin,
      const StateItem* end);
};

} //  end for namespace ShiftReduce
} //  end for namespace ZGen

#endif  //  end for __ZGEN_SHIFTREDUCE_DECODER_H__