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177 lines
5.6 KiB
C++
177 lines
5.6 KiB
C++
// $Id$
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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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#ifndef moses_TranslationOption_h
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#define moses_TranslationOption_h
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#include <map>
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#include <vector>
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#include <boost/functional/hash.hpp>
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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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namespace Moses
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{
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class PhraseDictionary;
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class GenerationDictionary;
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class FeatureFunction;
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class LexicalReordering;
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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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TargetPhrase m_targetPhrase; /*< output phrase when using this translation option */
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const InputPath *m_inputPath;
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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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typedef std::map<const LexicalReordering*, Scores> _ScoreCacheMap;
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_ScoreCacheMap m_lexReorderingScores;
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public:
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explicit TranslationOption(); // For initial hypo that does translate nothing
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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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/** 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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/** returns target phrase */
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inline const TargetPhrase &GetTargetPhrase() const {
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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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return m_sourceWordsRange;
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}
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/** returns source phrase */
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const InputPath &GetInputPath() const;
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void SetInputPath(const InputPath &inputPath);
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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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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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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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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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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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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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return m_targetPhrase.GetScoreBreakdown();
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}
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inline ScoreComponentCollection &GetScoreBreakdown() {
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return m_targetPhrase.GetScoreBreakdown();
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}
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void Evaluate(const InputType &input);
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/** returns cached scores */
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inline const Scores *GetLexReorderingScores(const LexicalReordering *scoreProducer) const {
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_ScoreCacheMap::const_iterator it = m_lexReorderingScores.find(scoreProducer);
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if(it == m_lexReorderingScores.end())
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return NULL;
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else
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return &(it->second);
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}
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void CacheLexReorderingScores(const LexicalReordering &scoreProducer, const Scores &score);
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TO_STRING();
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bool operator== (const TranslationOption &rhs) const {
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return m_sourceWordsRange == rhs.m_sourceWordsRange &&
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m_targetPhrase == rhs.m_targetPhrase;
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}
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};
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//XXX: This doesn't look at the alignment. Is this correct?
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inline size_t hash_value(const TranslationOption& translationOption)
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{
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size_t seed = 0;
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boost::hash_combine(seed, translationOption.GetTargetPhrase());
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boost::hash_combine(seed, translationOption.GetStartPos());
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boost::hash_combine(seed, translationOption.GetEndPos());
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return seed;
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}
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}
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#endif
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