mosesdecoder/moses/src/Hypothesis.h

// $Id$
// vim:tabstop=2

/***********************************************************************
Moses - factored phrase-based language decoder
Copyright (C) 2006 University of Edinburgh

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 <iostream>
#include <vector>
#include "Phrase.h"
#include "TypeDef.h"
#include "WordsBitmap.h"
#include "Sentence.h"
#include "Phrase.h"
#include "PhraseDictionaryMemory.h"
#include "GenerationDictionary.h"
#include "LanguageModelSingleFactor.h"
#include "ScoreComponentCollection.h"
#include "LexicalReordering.h"
#include "InputType.h"
#include "ObjectPool.h"
#include "AlignmentPair.h"

namespace Moses
{

class SquareMatrix;
class StaticData;
class TranslationOption;
class WordsRange;
class Hypothesis;
class FFState;

typedef std::vector<Hypothesis*> ArcList;

/** Used to store a state in the beam search
    for the best translation. With its link back to the previous hypothesis
    m_prevHypo, we can trace back to the sentence start to read of the
    (partial) translation to this point.
    
		The expansion of hypotheses is handled in the class Manager, which
    stores active hypothesis in the search in hypothesis stacks.
***/
class Hypothesis
{
	friend std::ostream& operator<<(std::ostream&, const Hypothesis&);

protected:
	static ObjectPool<Hypothesis> s_objectPool;
	
	const Hypothesis* m_prevHypo; /*! backpointer to previous hypothesis (from which this one was created) */
//	const Phrase			&m_targetPhrase; /*! target phrase being created at the current decoding step */
	const TargetPhrase			&m_targetPhrase; /*! target phrase being created at the current decoding step */
	Phrase const*     m_sourcePhrase; /*! input sentence */
	WordsBitmap				m_sourceCompleted; /*! keeps track of which words have been translated so far */
	//TODO: how to integrate this into confusion network framework; what if
	//it's a confusion network in the end???
	InputType const&  m_sourceInput;
	WordsRange				m_currSourceWordsRange; /*! source word positions of the last phrase that was used to create this hypothesis */
	WordsRange        m_currTargetWordsRange; /*! target word positions of the last phrase that was used to create this hypothesis */
  bool							m_wordDeleted;
	float							m_totalScore;  /*! score so far */
	float							m_futureScore; /*! estimated future cost to translate rest of sentence */
	ScoreComponentCollection m_scoreBreakdown; /*! detailed score break-down by components (for instance language model, word penalty, etc) */
	std::vector<const FFState*> m_ffStates;
	const Hypothesis 	*m_winningHypo;
	ArcList 					*m_arcList; /*! all arcs that end at the same trellis point as this hypothesis */
	AlignmentPair     m_alignPair;
	const TranslationOption *m_transOpt;

	int m_id; /*! numeric ID of this hypothesis, used for logging */
	static unsigned int s_HypothesesCreated; // Statistics: how many hypotheses were created in total	

	/*! used by initial seeding of the translation process */
	Hypothesis(InputType const& source, const TargetPhrase &emptyTarget);
	/*! used when creating a new hypothesis using a translation option (phrase translation) */
	Hypothesis(const Hypothesis &prevHypo, const TranslationOption &transOpt);

public:
	static ObjectPool<Hypothesis> &GetObjectPool()
	{
		return s_objectPool;
	}

	~Hypothesis();
	
	/** return the subclass of Hypothesis most appropriate to the given translation option */
	static Hypothesis* Create(const Hypothesis &prevHypo, const TranslationOption &transOpt, const Phrase* constraint);

	static Hypothesis* Create(const WordsBitmap &initialCoverage);

	/** return the subclass of Hypothesis most appropriate to the given target phrase */
	static Hypothesis* Create(InputType const& source, const TargetPhrase &emptyTarget);
	
	/** return the subclass of Hypothesis most appropriate to the given translation option */
	Hypothesis* CreateNext(const TranslationOption &transOpt, const Phrase* constraint) const;

	void PrintHypothesis() const;

	/** return target phrase used to create this hypothesis */
//	const Phrase &GetCurrTargetPhrase() const
	const TargetPhrase &GetCurrTargetPhrase() const
	{
		return m_targetPhrase;
	}

 // void PrintLMScores(const LMList &lmListInitial, const LMList	&lmListEnd) const;
 
	/** return input positions covered by the translation option (phrasal translation) used to create this hypothesis */
	inline const WordsRange &GetCurrSourceWordsRange() const
	{
		return m_currSourceWordsRange;
	}
	
	inline const WordsRange &GetCurrTargetWordsRange() const
	{
		return m_currTargetWordsRange;
	}
	
	/** output length of the translation option used to create this hypothesis */
	inline size_t GetCurrTargetLength() const
	{
		return m_currTargetWordsRange.GetNumWordsCovered();
	}

	void ResetScore();

	void CalcScore(const SquareMatrix &futureScore);

  float CalcExpectedScore( const SquareMatrix &futureScore );
  void CalcRemainingScore();

	int GetId()const
	{
		return m_id;
	}

	const Hypothesis* GetPrevHypo() const;

	/** length of the partial translation (from the start of the sentence) */
	inline size_t GetSize() const
	{
		return m_currTargetWordsRange.GetEndPos() + 1;
	}

	inline const Phrase* GetSourcePhrase() const
	{
		return m_sourcePhrase;
	}

	std::string GetSourcePhraseStringRep(const vector<FactorType> factorsToPrint) const;
	std::string GetTargetPhraseStringRep(const vector<FactorType> factorsToPrint) const;
	inline const TargetPhrase GetTargetPhrase() const { return m_targetPhrase; }
	std::string GetSourcePhraseStringRep() const;
	std::string GetTargetPhraseStringRep() const;

	/** curr - pos is relative from CURRENT hypothesis's starting index
	 * (ie, start of sentence would be some negative number, which is
	 * not allowed- USE WITH CAUTION) */
	inline const Word &GetCurrWord(size_t pos) const
	{
		return m_targetPhrase.GetWord(pos);
	}
	inline const Factor *GetCurrFactor(size_t pos, FactorType factorType) const
	{
		return m_targetPhrase.GetFactor(pos, factorType);
	}
	/** recursive - pos is relative from start of sentence */
	inline const Word &GetWord(size_t pos) const
	{
		const Hypothesis *hypo = this;
		while (pos < hypo->GetCurrTargetWordsRange().GetStartPos())
		{
			hypo = hypo->GetPrevHypo();
			assert(hypo != NULL);
		}
		return hypo->GetCurrWord(pos - hypo->GetCurrTargetWordsRange().GetStartPos());
	}
	inline const Factor* GetFactor(size_t pos, FactorType factorType) const
	{
		return GetWord(pos)[factorType];
	}

	/***
	 * \return The bitmap of source words we cover
	 */
	inline const WordsBitmap &GetWordsBitmap() const
	{
		return m_sourceCompleted;
	}

	inline bool IsSourceCompleted() const {
		return m_sourceCompleted.IsComplete();
	}

	int RecombineCompare(const Hypothesis &compare) const;
	
	void ToStream(std::ostream& out) const
	{
		if (m_prevHypo != NULL)
		{
			m_prevHypo->ToStream(out);
		}
		out << (Phrase) GetCurrTargetPhrase();
	}
	
	inline bool PrintAlignmentInfo() const{ return GetCurrTargetPhrase().PrintAlignmentInfo(); }
	
	void SourceAlignmentToStream(std::ostream& out) const
	{
		if (m_prevHypo != NULL)
		{
			m_prevHypo->SourceAlignmentToStream(out);
			AlignmentPhrase alignSourcePhrase=GetCurrTargetPhrase().GetAlignmentPair().GetAlignmentPhrase(Input);
			alignSourcePhrase.Shift(m_currTargetWordsRange.GetStartPos());
			out << " ";
 /*
			out << "\nGetCurrTargetPhrase(): " << GetCurrTargetPhrase();
			out << "\nm_currTargetWordsRange: " << m_currTargetWordsRange << "->";
*/
			alignSourcePhrase.print(out,m_currSourceWordsRange.GetStartPos());
		}
	}

	void TargetAlignmentToStream(std::ostream& out) const
	{
		if (m_prevHypo != NULL)
		{
			m_prevHypo->TargetAlignmentToStream(out);
			AlignmentPhrase alignTargetPhrase=GetCurrTargetPhrase().GetAlignmentPair().GetAlignmentPhrase(Output);
			alignTargetPhrase.Shift(m_currSourceWordsRange.GetStartPos());
			out << " ";
/*
			 out << "\nGetCurrTargetPhrase(): " << GetCurrTargetPhrase();
			out << "\nm_currSourceWordsRange: " << m_currSourceWordsRange << "->";
*/
			alignTargetPhrase.print(out,m_currTargetWordsRange.GetStartPos());
		}
	}

	TO_STRING();

	inline void SetWinningHypo(const Hypothesis *hypo)
	{
		m_winningHypo = hypo;
	}
	inline const Hypothesis *GetWinningHypo() const
	{
		return m_winningHypo;
	}
	
	void AddArc(Hypothesis *loserHypo);
	void CleanupArcList();

	//! returns a list alternative previous hypotheses (or NULL if n-best support is disabled)
	inline const ArcList* GetArcList() const
	{
		return m_arcList;
	}
	const ScoreComponentCollection& GetScoreBreakdown() const
	{
		return m_scoreBreakdown;
	}
	float GetTotalScore() const { return m_totalScore; }
	float GetScore() const { return m_totalScore-m_futureScore; }
	
	
	
	//! vector of what source words were aligned to each target
	const AlignmentPair &GetAlignmentPair() const
	{
		return m_alignPair;
	}
	//! target span that trans opt would populate if applied to this hypo. Used for alignment check
	size_t GetNextStartPos(const TranslationOption &transOpt) const;
	
	std::vector<std::vector<unsigned int> > *GetLMStats() const { return NULL; }

	static unsigned int GetHypothesesCreated()
	{
		return s_HypothesesCreated;
	}

	const ScoreComponentCollection &GetCachedReorderingScore() const;

	const TranslationOption &GetTranslationOption() const
	{ return *m_transOpt; }
};

std::ostream& operator<<(std::ostream& out, const Hypothesis& hypothesis);

// sorting helper
struct CompareHypothesisTotalScore
{
	bool operator()(const Hypothesis* hypo1, const Hypothesis* hypo2) const
	{
		return hypo1->GetTotalScore() > hypo2->GetTotalScore();
	}
};

#ifdef USE_HYPO_POOL

#define FREEHYPO(hypo) \
{ \
	ObjectPool<Hypothesis> &pool = Hypothesis::GetObjectPool(); \
	pool.freeObject(hypo); \
} \

#else
#define FREEHYPO(hypo) delete hypo
#endif

/** defines less-than relation on hypotheses.
* The particular order is not important for us, we need just to figure out
* which hypothesis are equal based on:
*   the last n-1 target words are the same
*   and the covers (source words translated) are the same
*/
class HypothesisRecombinationOrderer
{
public:
	bool operator()(const Hypothesis* hypoA, const Hypothesis* hypoB) const
	{
		return hypoA->RecombineCompare(*hypoB) < 0;
	}
};

}