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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
***********************************************************************/
#include <assert.h>
#include <limits>
#include <iostream>
#include <fstream>
#include "ngram.h"
#include "lmtable.h"
#include "dictionary.h"
#include "LanguageModel_IRST.h"
#include "TypeDef.h"
#include "Util.h"
#include "FactorCollection.h"
#include "Phrase.h"
#include "InputFileStream.h"
using namespace std;
LanguageModel_IRST::LanguageModel_IRST()
:m_lmtb(0)
{
}
LanguageModel_IRST::~LanguageModel_IRST()
{
delete m_lmtb;
}
void LanguageModel_IRST::Load(const std::string &fileName
, FactorCollection &factorCollection
, FactorType factorType
, float weight
, size_t nGramOrder)
{
m_factorType = factorType;
m_weight = weight;
m_nGramOrder = nGramOrder;
m_filename = fileName;
InputFileStream inp(fileName);
m_lmtb = new lmtable(inp);
// LM can be ok, just outputs warnings
CreateFactors(factorCollection);
m_unknownId = m_lmtb->dict->oovcode();
std::cerr << "IRST: m_unknownId=" << m_unknownId << std::endl;
}
void LanguageModel_IRST::CreateFactors(FactorCollection &factorCollection)
{ // add factors which have srilm id
// code copied & paste from SRI LM class. should do template function
std::map<size_t, int> lmIdMap;
size_t maxFactorId = 0; // to create lookup vector later on
dict_entry *entry;
dictionary_iter iter(m_lmtb->dict);
while ( (entry = iter.next()) != NULL)
{
size_t factorId = factorCollection.AddFactor(Output, m_factorType, entry->word)->GetId();
lmIdMap[factorId] = entry->code;
maxFactorId = (factorId > maxFactorId) ? factorId : maxFactorId;
}
int lmId;
size_t factorId;
lmId = GetLmID(BOS_);
m_sentenceStart = factorCollection.AddFactor(Output, m_factorType, SENTENCE_START);
factorId = m_sentenceStart->GetId();
lmIdMap[factorId] = lmId;
lmId = GetLmID(EOS_);
m_sentenceEnd = factorCollection.AddFactor(Output, m_factorType, SENTENCE_END);
factorId = m_sentenceEnd->GetId();
lmIdMap[factorId] = lmId;
// add to lookup vector in object
m_lmIdLookup.resize(maxFactorId+1);
fill(m_lmIdLookup.begin(), m_lmIdLookup.end(), m_unknownId);
map<size_t, int>::iterator iterMap;
for (iterMap = lmIdMap.begin() ; iterMap != lmIdMap.end() ; ++iterMap)
{
m_lmIdLookup[iterMap->first] = iterMap->second;
}
}
int LanguageModel_IRST::GetLmID( const std::string &str ) const
{
return m_lmtb->dict->encode( str.c_str() );
}
int LanguageModel_IRST::GetLmID( const Factor *factor ) const
{
size_t factorId = factor->GetId();
return ( factorId >= m_lmIdLookup.size()) ? m_unknownId : m_lmIdLookup[factorId];
}
float LanguageModel_IRST::GetValue(const vector<const Factor*> &contextFactor, State* finalState) const
{
// set up context
size_t count = contextFactor.size();
ngram ng(m_lmtb->dict);
for (size_t i = 0 ; i < count ; i++)
{
#undef CDYER_DEBUG_LMSCORE
#ifdef CDYER_DEBUG_LMSCORE
std::cout << i <<"="<<contextFactor[i]->GetLmId().irst <<"," << contextFactor[i]->GetString()<<" ";
#endif
int lmId = GetLmID(contextFactor[i]);
ng.pushc(lmId);
}
#ifdef CDYER_DEBUG_LMSCORE
std::cout <<" (ng='" << ng << "')\n";
#endif
if (finalState) {
assert("!LM State needs to be implemented!");
}
return TransformScore(m_lmtb->prob(ng));
}
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