mirror of
https://github.com/moses-smt/mosesdecoder.git
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137 lines
4.1 KiB
C++
137 lines
4.1 KiB
C++
/***********************************************************************
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Moses - factored phrase-based language decoder
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Copyright (C) 2012- 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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/**
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* This contains extra features that can be added to the scorer. To add a new feature:
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* 1. Implement a subclass of ScoreFeature
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* 2. Updated ScoreFeatureManager.configure() to configure your feature, and usage() to
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* display usage info.
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* 3. Write unit tests (see ScoreFeatureTest.cpp) and regression tests
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**/
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#pragma once
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#include <string>
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#include <map>
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#include <vector>
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#include <boost/shared_ptr.hpp>
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#include "util/exception.hh"
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#include "PhraseAlignment.h"
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namespace MosesTraining
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{
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struct MaybeLog{
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MaybeLog(bool useLog, float negativeLog):
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m_useLog(useLog), m_negativeLog(negativeLog) {}
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inline float operator() (float a) const
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{ return m_useLog ? m_negativeLog*log(a) : a; }
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float m_useLog;
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float m_negativeLog;
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};
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class ScoreFeatureArgumentException : public util::Exception
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{
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public:
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ScoreFeatureArgumentException() throw() {*this << "Unable to configure features: ";}
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~ScoreFeatureArgumentException() throw() {}
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};
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/** Passed to each feature to be used to calculate its values */
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struct ScoreFeatureContext
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{
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ScoreFeatureContext(
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const PhraseAlignmentCollection &thePhrasePair,
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float theCount, /* Total counts of all phrase pairs*/
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const MaybeLog& theMaybeLog
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) :
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phrasePair(thePhrasePair),
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count(theCount),
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maybeLog(theMaybeLog)
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{}
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const PhraseAlignmentCollection& phrasePair;
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float count;
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MaybeLog maybeLog;
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};
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/**
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* Abstract base class for extra features that can be added to the phrase table
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* during scoring.
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**/
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class ScoreFeature
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{
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public:
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/** Add the values for this feature function. */
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virtual void add(const ScoreFeatureContext& context,
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std::vector<float>& denseValues,
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std::map<std::string,float>& sparseValues) const = 0;
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/** Return true if the two phrase pairs are equal from the point of this feature. Assume
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that they already compare true according to PhraseAlignment.equals()
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**/
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virtual bool equals(const PhraseAlignment& lhs, const PhraseAlignment& rhs) const = 0;
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virtual ~ScoreFeature() {}
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};
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typedef boost::shared_ptr<ScoreFeature> ScoreFeaturePtr;
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class ScoreFeatureManager
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{
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public:
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ScoreFeatureManager():
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m_includeSentenceId(false) {}
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/** To be appended to the score usage message */
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const std::string& usage() const;
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/** Pass the unused command-line arguments to configure the extra features */
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void configure(const std::vector<std::string> args);
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/** Add all the features */
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void addFeatures(const ScoreFeatureContext& context,
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std::vector<float>& denseValues,
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std::map<std::string,float>& sparseValues) const;
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/**
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* Used to tell if the PhraseAlignment should be considered the same by all
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* extended features.
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**/
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bool equals(const PhraseAlignment& lhs, const PhraseAlignment& rhs) const;
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const std::vector<ScoreFeaturePtr>& getFeatures() const {return m_features;}
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/** Do we need to include sentence ids in phrase pairs? */
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bool includeSentenceId() const {return m_includeSentenceId;}
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private:
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std::vector<ScoreFeaturePtr> m_features;
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bool m_includeSentenceId;
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};
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}
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