2008-06-11 14:52:57 +04:00
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// $Id$
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/***********************************************************************
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Moses - factored phrase-based language decoder
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Copyright (C) 2006 University of Edinburgh
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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***********************************************************************/
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#pragma once
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#include <vector>
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#include "WordsBitmap.h"
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#include "WordsRange.h"
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#include "Phrase.h"
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#include "TargetPhrase.h"
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#include "Hypothesis.h"
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#include "Util.h"
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#include "TypeDef.h"
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#include "ScoreComponentCollection.h"
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#include "StaticData.h"
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2008-10-09 03:51:26 +04:00
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namespace Moses
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{
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2008-06-11 14:52:57 +04:00
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class PhraseDictionary;
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class GenerationDictionary;
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/** Available phrase translation for a particular sentence pair.
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* In a multi-factor model, this is expanded from the entries in the
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* translation tables and generation tables (and pruned to the maximum
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* number allowed). By pre-computing the allowable phrase translations,
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* efficient beam search in Manager is possible when expanding instances
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* of the class Hypothesis - the states in the search.
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*
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* A translation option contains source and target phrase, aggregate
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* and details scores (in m_scoreBreakdown), including an estimate
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* how expensive this option will be in search (used to build the
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* future cost matrix.)
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*
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* m_targetPhrase points to a phrase-table entry.
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* The source word range is zero-indexed, so it can't refer to an empty range. The target phrase may be empty.
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*/
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class TranslationOption
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{
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friend std::ostream& operator<<(std::ostream& out, const TranslationOption& possibleTranslation);
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protected:
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2008-09-12 22:09:06 +04:00
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TargetPhrase m_targetPhrase; /*< output phrase when using this translation option */
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2008-06-11 14:52:57 +04:00
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Phrase *m_sourcePhrase; /*< input phrase translated by this */
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const WordsRange m_sourceWordsRange; /*< word position in the input that are covered by this translation option */
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float m_futureScore; /*< estimate of total cost when using this translation option, includes language model probabilities */
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std::vector<TranslationOption*> m_linkedTransOpts; /* list of linked TOs which must be included with this in any hypothesis */
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//! in TranslationOption, m_scoreBreakdown is not complete. It cannot,
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//! for example, know the full n-gram score since the length of the
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//! TargetPhrase may be shorter than the n-gram order. But, if it is
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//! possible to estimate, it is included here.
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ScoreComponentCollection m_scoreBreakdown;
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ScoreComponentCollection m_reordering;
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public:
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/** constructor. Used by initial translation step */
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TranslationOption(const WordsRange &wordsRange
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, const TargetPhrase &targetPhrase
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, const InputType &inputType);
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/** constructor. Used to create trans opt from unknown word */
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TranslationOption(const WordsRange &wordsRange
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, const TargetPhrase &targetPhrase
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, const InputType &inputType
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, int);
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/** copy constructor */
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TranslationOption(const TranslationOption ©);
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/** copy constructor, but change words range. used by caching */
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TranslationOption(const TranslationOption ©, const WordsRange &sourceWordsRange);
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~TranslationOption()
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{
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delete m_sourcePhrase;
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}
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/** returns true if all feature types in featuresToCheck are compatible between the two phrases */
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bool IsCompatible(const Phrase& phrase, const std::vector<FactorType>& featuresToCheck) const;
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/** used when precomputing (composing) translation options */
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void MergeNewFeatures(const Phrase& phrase, const ScoreComponentCollection& score, const std::vector<FactorType>& featuresToMerge);
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/** returns target phrase */
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inline const TargetPhrase &GetTargetPhrase() const
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{
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return m_targetPhrase;
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}
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/** returns source word range */
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inline const WordsRange &GetSourceWordsRange() const
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{
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return m_sourceWordsRange;
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}
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/** returns source phrase */
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const Phrase *GetSourcePhrase() const
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{
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return m_sourcePhrase;
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}
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/** returns linked TOs */
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inline const std::vector<TranslationOption*> &GetLinkedTransOpts() const
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{
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return m_linkedTransOpts;
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}
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/** add link to another TO */
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inline void AddLinkedTransOpt(TranslationOption* to)
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{
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m_linkedTransOpts.push_back(to);
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}
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/** whether source span overlaps with those of a hypothesis */
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bool Overlap(const Hypothesis &hypothesis) const;
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/** return start index of source phrase */
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inline size_t GetStartPos() const
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{
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return m_sourceWordsRange.GetStartPos();
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}
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/** return end index of source phrase */
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inline size_t GetEndPos() const
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{
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return m_sourceWordsRange.GetEndPos();
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}
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/** return length of source phrase */
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inline size_t GetSize() const
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{
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return m_sourceWordsRange.GetEndPos() - m_sourceWordsRange.GetStartPos() + 1;
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}
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/** return estimate of total cost of this option */
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inline float GetFutureScore() const
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{
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return m_futureScore;
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}
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/** return true if the source phrase translates into nothing */
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inline bool IsDeletionOption() const
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{
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return m_targetPhrase.GetSize() == 0;
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}
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/** returns detailed component scores */
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inline const ScoreComponentCollection &GetScoreBreakdown() const
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{
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return m_scoreBreakdown;
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}
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/** returns detailed component scores */
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inline const ScoreComponentCollection &GetReorderingScore() const
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{
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return m_reordering;
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}
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/** Calculate future score and n-gram score of this trans option, plus the score breakdowns */
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void CalcScore();
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void CacheReorderingProb(const LexicalReordering &lexreordering
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, const Score &score);
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TO_STRING();
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};
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2008-10-09 03:51:26 +04:00
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}
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2008-06-11 14:52:57 +04:00
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