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https://github.com/moses-smt/mosesdecoder.git
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92 lines
3.2 KiB
C++
92 lines
3.2 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_LanguageModelBackward_h
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#define moses_LanguageModelBackward_h
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#include <string>
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#include "moses/LM/Ken.h"
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#include "moses/LM/BackwardLMState.h"
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#include "lm/state.hh"
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namespace Moses
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{
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//! This will also load. Returns a templated backward LM.
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LanguageModel *ConstructBackwardLM(const std::string &file, FactorType factorType, bool lazy);
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class FFState;
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// template<typename M> class BackwardLanguageModelTest;
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class BackwardLanguageModelTest;
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/*
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* An implementation of single factor backward LM using Kenneth's code.
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*/
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template <class Model> class BackwardLanguageModel : public LanguageModelKen<Model>
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{
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public:
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BackwardLanguageModel(const std::string &file, FactorType factorType, bool lazy);
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virtual const FFState *EmptyHypothesisState(const InputType &/*input*/) const;
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virtual void CalcScore(const Phrase &phrase, float &fullScore, float &ngramScore, size_t &oovCount) const;
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virtual FFState *Evaluate(const Hypothesis &hypo, const FFState *ps, ScoreComponentCollection *out) const;
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FFState *Evaluate(const Phrase &phrase, const FFState *ps, float &returnedScore) const;
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private:
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// These lines are required to make the parent class's protected members visible to this class
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using LanguageModelKen<Model>::m_ngram;
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using LanguageModelKen<Model>::m_beginSentenceFactor;
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using LanguageModelKen<Model>::m_factorType;
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using LanguageModelKen<Model>::TranslateID;
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// friend class Moses::BackwardLanguageModelTest<Model>;
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friend class Moses::BackwardLanguageModelTest;
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/*
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lm::ngram::ChartState* GetState(FFState *ffState) {
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return NULL;
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}
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*/
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/*
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double Score(FFState *ffState) {
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BackwardLMState *lmState = static_cast< BackwardLMState* >(ffState);
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lm::ngram::ChartState &state = lmState->state;
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lm::ngram::RuleScore<Model> ruleScore(*m_ngram, lmState);
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return ruleScore.Finish();
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}
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*/
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};
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} // namespace Moses
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#endif
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// To create a sample backward language model using SRILM:
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//
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// (ngram-count and reverse-text are SRILM programs)
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//
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// head -n 49 ./contrib/synlm/hhmm/LICENSE | tail -n 45 | tr '\n' ' ' | ./scripts/ems/support/split-sentences.perl | ./scripts/tokenizer/lowercase.perl | ./scripts/tokenizer/tokenizer.perl | reverse-text | ngram-count -order 3 -text - -lm - > lm/backward.arpa
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