mosesdecoder/moses/ChartHypothesis.h

// vim:tabstop=2
/***********************************************************************
 Moses - factored phrase-based language decoder
 Copyright (C) 2010 Hieu Hoang

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 ***********************************************************************/

#pragma once

#include <vector>
#include "Util.h"
#include "WordsRange.h"
#include "ScoreComponentCollection.h"
#include "Phrase.h"
#include "ChartTranslationOptions.h"
#include "ObjectPool.h"

namespace Moses
{

class ChartHypothesis;
class ChartManager;
class RuleCubeItem;

typedef std::vector<ChartHypothesis*> ChartArcList;

/** a hypothesis in the hierarchical/syntax decoder.
 * Contain a pointer to the current target phrase, a vector of previous hypos, and some scores
 */
class ChartHypothesis
{
  friend std::ostream& operator<<(std::ostream&, const ChartHypothesis&);

protected:
#ifdef USE_HYPO_POOL
  static ObjectPool<ChartHypothesis> s_objectPool;
#endif

  const TargetPhrase &m_targetPhrase;

  WordsRange					m_currSourceWordsRange;
	std::vector<const FFState*> m_ffStates; /*! stateful feature function states */
  ScoreComponentCollection m_scoreBreakdown /*! detailed score break-down by components (for instance language model, word penalty, etc) */
  ,m_lmNGram
  ,m_lmPrefix;
  float m_totalScore;

  ChartArcList 					*m_arcList; /*! all arcs that end at the same trellis point as this hypothesis */
  const ChartHypothesis 	*m_winningHypo;

  std::vector<const ChartHypothesis*> m_prevHypos; // always sorted by source position?

  ChartManager& m_manager;

  unsigned m_id; /* pkoehn wants to log the order in which hypotheses were generated */

  //! not implemented
  ChartHypothesis(); 
  
  //! not implemented
  ChartHypothesis(const ChartHypothesis &copy);

public:
#ifdef USE_HYPO_POOL
  void *operator new(size_t /* num_bytes */) {
    void *ptr = s_objectPool.getPtr();
    return ptr;
  }

  //! delete \param hypo. Works with object pool too
  static void Delete(ChartHypothesis *hypo) {
    s_objectPool.freeObject(hypo);
  }
#else
  //! delete \param hypo. Works with object pool too
  static void Delete(ChartHypothesis *hypo) {
    delete hypo;
  }
#endif

  ChartHypothesis(const ChartTranslationOptions &, const RuleCubeItem &item,
                  ChartManager &manager);

  ~ChartHypothesis();

  unsigned GetId() const { return m_id; }

  //! Get the rule that created this hypothesis
  const TargetPhrase &GetCurrTargetPhrase()const {
    return m_targetPhrase;
  }
  
  //! the source range that this hypothesis spans
  const WordsRange &GetCurrSourceRange()const {
    return m_currSourceWordsRange;
  }
  
  //! the arc list when creating n-best lists
  inline const ChartArcList* GetArcList() const {
    return m_arcList;
  }
  
  //! the feature function states for a particular feature \param featureID
	inline const FFState* GetFFState( size_t featureID ) const {
		return m_ffStates[ featureID ];
	}
  
  //! reference back to the manager
	inline const ChartManager& GetManager() const { return m_manager; }

  void CreateOutputPhrase(Phrase &outPhrase) const;
  Phrase GetOutputPhrase() const;

	int RecombineCompare(const ChartHypothesis &compare) const;

  void CalcScore();

  void AddArc(ChartHypothesis *loserHypo);
  void CleanupArcList();
  void SetWinningHypo(const ChartHypothesis *hypo);

  //! get the unweighted score for each feature function
  const ScoreComponentCollection &GetScoreBreakdown() const 
  { return m_scoreBreakdown; }
  
  //! Get the weighted total score
  float GetTotalScore() const 
  { return m_totalScore; }

  //! vector of previous hypotheses this hypo is built on 
  const std::vector<const ChartHypothesis*> &GetPrevHypos() const
  { return m_prevHypos; }

  //! get a particular previous hypos
	const ChartHypothesis* GetPrevHypo(size_t pos) const {
		return m_prevHypos[pos];
	}
  
  //! get the constituency label that covers this hypo
  const Word &GetTargetLHS() const {
    return GetCurrTargetPhrase().GetTargetLHS();
  }

  //! get the best hypo in the arc list when doing n-best list creation. It's either this hypothesis, or the best hypo is this hypo is in the arc list
	const ChartHypothesis* GetWinningHypothesis() const 
  {	return m_winningHypo;	}

  TO_STRING();

}; // class ChartHypothesis

}