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// $Id$
/***********************************************************************
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 <vector>
#include "WordsBitmap.h"
#include "WordsRange.h"
#include "Phrase.h"
#include "TargetPhrase.h"
#include "Hypothesis.h"
#include "Util.h"
#include "TypeDef.h"
#include "ScoreComponentCollection.h"
#include "StaticData.h"
class PhraseDictionary;
class GenerationDictionary;
/** Available phrase translation for a particular sentence pair.
* In a multi-factor model, this is expanded from the entries in the
* translation tables and generation tables (and pruned to the maximum
* number allowed). By pre-computing the allowable phrase translations,
* efficient beam search in Manager is possible when expanding instances
* of the class Hypothesis - the states in the search.
*
* A translation option contains source and target phrase, aggregate
* and details scores (in m_scoreBreakdown), including an estimate
* how expensive this option will be in search (used to build the
* future cost matrix.)
*
* m_targetPhrase points to a phrase-table entry.
* The source word range is zero-indexed, so it can't refer to an empty range. The target phrase may be empty.
*/
class TranslationOption
{
friend std::ostream& operator<<(std::ostream& out, const TranslationOption& possibleTranslation);
protected:
Phrase m_targetPhrase; /*< output phrase when using this translation option */
Phrase *m_sourcePhrase; /*< input phrase translated by this */
const WordsRange m_sourceWordsRange; /*< word position in the input that are covered by this translation option */
float m_futureScore; /*< estimate of total cost when using this translation option, includes language model probabilities */
//! in TranslationOption, m_scoreBreakdown is not complete. It cannot,
//! for example, know the full n-gram score since the length of the
//! TargetPhrase may be shorter than the n-gram order. But, if it is
//! possible to estimate, it is included here.
ScoreComponentCollection m_scoreBreakdown;
ScoreComponentCollection m_reordering;
public:
/** constructor. Used by initial translation step */
TranslationOption(const WordsRange &wordsRange
, const TargetPhrase &targetPhrase
, const InputType &inputType);
/** constructor. Used to create trans opt from unknown word */
TranslationOption(const WordsRange &wordsRange
, const TargetPhrase &targetPhrase
, const InputType &inputType
, int);
/** copy constructor */
TranslationOption(const TranslationOption ©);
/** copy constructor, but change words range. used by caching */
TranslationOption(const TranslationOption ©, const WordsRange &sourceWordsRange);
~TranslationOption()
{
delete m_sourcePhrase;
}
/** returns true if all feature types in featuresToCheck are compatible between the two phrases */
bool IsCompatible(const Phrase& phrase, const std::vector<FactorType>& featuresToCheck) const;
/** used when precomputing (composing) translation options */
void MergeNewFeatures(const Phrase& phrase, const ScoreComponentCollection& score, const std::vector<FactorType>& featuresToMerge);
/** returns target phrase */
inline const Phrase &GetTargetPhrase() const
{
return m_targetPhrase;
}
/** returns source word range */
inline const WordsRange &GetSourceWordsRange() const
{
return m_sourceWordsRange;
}
/** returns source phrase */
const Phrase *GetSourcePhrase() const
{
return m_sourcePhrase;
}
/** whether source span overlaps with those of a hypothesis */
bool Overlap(const Hypothesis &hypothesis) const;
/** return start index of source phrase */
inline size_t GetStartPos() const
{
return m_sourceWordsRange.GetStartPos();
}
/** return end index of source phrase */
inline size_t GetEndPos() const
{
return m_sourceWordsRange.GetEndPos();
}
/** return length of source phrase */
inline size_t GetSize() const
{
return m_sourceWordsRange.GetEndPos() - m_sourceWordsRange.GetStartPos() + 1;
}
/** return estimate of total cost of this option */
inline float GetFutureScore() const
{
return m_futureScore;
}
/** return true if the source phrase translates into nothing */
inline bool IsDeletionOption() const
{
return m_targetPhrase.GetSize() == 0;
}
/** returns detailed component scores */
inline const ScoreComponentCollection &GetScoreBreakdown() const
{
return m_scoreBreakdown;
}
/** returns detailed component scores */
inline const ScoreComponentCollection &GetReorderingScore() const
{
return m_reordering;
}
/** Calculate future score and n-gram score of this trans option, plus the score breakdowns */
void CalcScore();
void CacheReorderingProb(const LexicalReordering &lexreordering
, const Score &score);
TO_STRING();
};
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