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// $Id$
// vim:tabstop=2
/***********************************************************************
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 <algorithm>
#include "TranslationOptionCollection.h"
#include "Sentence.h"
#include "DecodeStep.h"
#include "LanguageModel.h"
#include "PhraseDictionaryMemory.h"
#include "FactorCollection.h"
#include "InputType.h"
#include "Util.h"
#include "StaticData.h"
#include "DecodeStepTranslation.h"
#include "DecodeGraph.h"
using namespace std;
/** constructor; since translation options are indexed by coverage span, the corresponding data structure is initialized here
* This fn should be called by inherited classes
*/
TranslationOptionCollection::TranslationOptionCollection(InputType const& src, size_t maxNoTransOptPerCoverage)
: m_source(src)
,m_futureScore(src.GetSize())
,m_maxNoTransOptPerCoverage(maxNoTransOptPerCoverage)
{
// create 2-d vector
size_t size = src.GetSize();
for (size_t startPos = 0 ; startPos < size ; ++startPos)
{
m_collection.push_back( vector< TranslationOptionList >() );
size_t maxSize = size - startPos + 1;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; ++endPos)
{
m_collection[startPos].push_back( TranslationOptionList() );
}
}
}
/** destructor, clears out data structures */
TranslationOptionCollection::~TranslationOptionCollection()
{
size_t size = m_source.GetSize();
for (size_t startPos = 0 ; startPos < size ; ++startPos)
{
size_t maxSize = size - startPos + 1;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; ++endPos)
{
RemoveAllInColl(GetTranslationOptionList(startPos, endPos));
}
}
RemoveAllInColl(m_unksrcs);
}
/** helper for pruning */
bool CompareTranslationOption(const TranslationOption *a, const TranslationOption *b)
{
return a->GetFutureScore() > b->GetFutureScore();
}
void TranslationOptionCollection::Prune()
{
size_t size = m_source.GetSize();
// prune to max no. of trans opt
if (m_maxNoTransOptPerCoverage == 0)
return;
size_t total = 0;
size_t totalPruned = 0;
for (size_t startPos = 0 ; startPos < size; ++startPos)
{
size_t maxSize = size - startPos;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; ++endPos)
{
TranslationOptionList &fullList = GetTranslationOptionList(startPos, endPos);
total += fullList.size();
if (fullList.size() <= m_maxNoTransOptPerCoverage)
continue;
// sort in vector
nth_element(fullList.begin(), fullList.begin() + m_maxNoTransOptPerCoverage, fullList.end(), CompareTranslationOption);
totalPruned += fullList.size() - m_maxNoTransOptPerCoverage;
// delete the rest
for (size_t i = m_maxNoTransOptPerCoverage ; i < fullList.size() ; ++i)
{
delete fullList[i];
}
fullList.resize(m_maxNoTransOptPerCoverage);
}
}
VERBOSE(2," Total translation options: " << total << std::endl
<< "Total translation options pruned: " << totalPruned << std::endl);
}
/** Force a creation of a translation option where there are none for a particular source position.
* ie. where a source word has not been translated, create a translation option by
* 1. not observing the table limits on phrase/generation tables
* 2. using the handler ProcessUnknownWord()
* Call this function once translation option collection has been filled with translation options
*
* This function calls for unknown words is complicated by the fact it must handle different input types.
* The call stack is
* Base::ProcessUnknownWord()
* Inherited::ProcessUnknownWord(position)
* Base::ProcessOneUnknownWord()
*
* \param decodeStepList list of decoding steps
* \param factorCollection input sentence with all factors
*/
void TranslationOptionCollection::ProcessUnknownWord(const std::vector <DecodeGraph*> &decodeStepVL)
{
size_t size = m_source.GetSize();
// try to translation for coverage with no trans by expanding table limit
for (size_t startVL = 0 ; startVL < decodeStepVL.size() ; startVL++)
{
const DecodeGraph &decodeStepList = *decodeStepVL[startVL];
for (size_t pos = 0 ; pos < size ; ++pos)
{
TranslationOptionList &fullList = GetTranslationOptionList(pos, pos);
size_t numTransOpt = fullList.size();
if (numTransOpt == 0)
{
CreateTranslationOptionsForRange(decodeStepList
, pos, pos, false);
}
}
}
bool alwaysCreateDirectTranslationOption = StaticData::Instance().IsAlwaysCreateDirectTranslationOption();
// create unknown words for 1 word coverage where we don't have any trans options
for (size_t pos = 0 ; pos < size ; ++pos)
{
TranslationOptionList &fullList = GetTranslationOptionList(pos, pos);
if (fullList.size() == 0 || alwaysCreateDirectTranslationOption)
ProcessUnknownWord(pos);
}
}
/** special handling of ONE unknown words. Either add temporarily add word to translation table,
* or drop the translation.
* This function should be called by the ProcessOneUnknownWord() in the inherited class
* At the moment, this unknown word handler is a bit of a hack, if copies over each factor from source
* to target word, or uses the 'UNK' factor.
* Ideally, this function should be in a class which can be expanded upon, for example,
* to create a morphologically aware handler.
*
* \param sourceWord the unknown word
* \param sourcePos
* \param factorCollection input sentence with all factors
*/
void TranslationOptionCollection::ProcessOneUnknownWord(const Word &sourceWord,
size_t sourcePos, size_t length)
{
// unknown word, add as trans opt
FactorCollection &factorCollection = FactorCollection::Instance();
size_t isDigit = 0;
if (StaticData::Instance().GetDropUnknown())
{
const Factor *f = sourceWord[0]; // TODO hack. shouldn't know which factor is surface
const string &s = f->GetString();
isDigit = s.find_first_of("0123456789");
if (isDigit == string::npos)
isDigit = 0;
else
isDigit = 1;
// modify the starting bitmap
}
Phrase* m_unksrc = new Phrase(Input); m_unksrc->AddWord() = sourceWord;
m_unksrcs.push_back(m_unksrc);
TranslationOption *transOpt;
if (! StaticData::Instance().GetDropUnknown() || isDigit)
{
// add to dictionary
TargetPhrase targetPhrase(Output);
Word &targetWord = targetPhrase.AddWord();
for (unsigned int currFactor = 0 ; currFactor < MAX_NUM_FACTORS ; currFactor++)
{
FactorType factorType = static_cast<FactorType>(currFactor);
const Factor *sourceFactor = sourceWord[currFactor];
if (sourceFactor == NULL)
targetWord[factorType] = factorCollection.AddFactor(Output, factorType, UNKNOWN_FACTOR);
else
targetWord[factorType] = factorCollection.AddFactor(Output, factorType, sourceFactor->GetString());
}
targetPhrase.SetScore();
targetPhrase.SetSourcePhrase(m_unksrc);
transOpt = new TranslationOption(WordsRange(sourcePos, sourcePos + length - 1), targetPhrase, m_source, 0);
}
else
{ // drop source word. create blank trans opt
TargetPhrase targetPhrase(Output);
targetPhrase.SetSourcePhrase(m_unksrc);
transOpt = new TranslationOption(WordsRange(sourcePos, sourcePos + length - 1), targetPhrase, m_source, 0);
}
transOpt->CalcScore();
Add(transOpt);
}
/** compute future score matrix in a dynamic programming fashion.
* This matrix used in search.
* Call this function once translation option collection has been filled with translation options
*/
void TranslationOptionCollection::CalcFutureScore()
{
// setup the matrix (ignore lower triangle, set upper triangle to -inf
size_t size = m_source.GetSize(); // the width of the matrix
for(size_t row=0; row<size; row++) {
for(size_t col=row; col<size; col++) {
m_futureScore.SetScore(row, col, -numeric_limits<float>::infinity());
}
}
// walk all the translation options and record the cheapest option for each span
for (size_t startPos = 0 ; startPos < m_source.GetSize() ; ++startPos)
{
size_t maxSize = m_source.GetSize() - startPos;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; ++endPos)
{
TranslationOptionList &transOptList = GetTranslationOptionList(startPos, endPos);
TranslationOptionList::const_iterator iterTransOpt;
for(iterTransOpt = transOptList.begin() ; iterTransOpt != transOptList.end() ; ++iterTransOpt)
{
const TranslationOption &transOpt = **iterTransOpt;
float score = transOpt.GetFutureScore();
if (score > m_futureScore.GetScore(startPos, endPos))
m_futureScore.SetScore(startPos, endPos, score);
}
}
}
// now fill all the cells in the strictly upper triangle
// there is no way to modify the diagonal now, in the case
// where no translation option covers a single-word span,
// we leave the +inf in the matrix
// like in chart parsing we want each cell to contain the highest score
// of the full-span trOpt or the sum of scores of joining two smaller spans
for(size_t colstart = 1; colstart < size ; colstart++) {
for(size_t diagshift = 0; diagshift < size-colstart ; diagshift++) {
size_t startPos = diagshift;
size_t endPos = colstart+diagshift;
for(size_t joinAt = startPos; joinAt < endPos ; joinAt++) {
float joinedScore = m_futureScore.GetScore(startPos, joinAt)
+ m_futureScore.GetScore(joinAt+1, endPos);
/* // uncomment to see the cell filling scheme
TRACE_ERR( "[" <<startPos<<","<<endPos<<"] <-? ["<<startPos<<","<<joinAt<<"]+["<<joinAt+1<<","<<endPos
<< "] (colstart: "<<colstart<<", diagshift: "<<diagshift<<")"<<endl);
*/
if (joinedScore > m_futureScore.GetScore(startPos, endPos))
m_futureScore.SetScore(startPos, endPos, joinedScore);
}
}
}
IFVERBOSE(3)
{
int total = 0;
for(size_t row=0; row<size; row++)
{
size_t maxSize = size - row;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for(size_t col=row; col<row+maxSize; col++)
{
int count = GetTranslationOptionList(row, col).size();
TRACE_ERR( "translation options spanning from "
<< row <<" to "<< col <<" is "
<< count <<endl);
total += count;
}
}
TRACE_ERR( "translation options generated in total: "<< total << endl);
for(size_t row=0; row<size; row++)
for(size_t col=row; col<size; col++)
TRACE_ERR( "future cost from "<< row <<" to "<< col <<" is "<< m_futureScore.GetScore(row, col) <<endl);
}
}
/** Create all possible translations from the phrase tables
* for a particular input sentence. This implies applying all
* translation and generation steps. Also computes future cost matrix.
* \param decodeStepList list of decoding steps
* \param factorCollection input sentence with all factors
*/
void TranslationOptionCollection::CreateTranslationOptions(const vector <DecodeGraph*> &decodeStepVL)
{
// loop over all substrings of the source sentence, look them up
// in the phraseDictionary (which is the- possibly filtered-- phrase
// table loaded on initialization), generate TranslationOption objects
// for all phrases
for (size_t startVL = 0 ; startVL < decodeStepVL.size() ; startVL++)
{
const DecodeGraph &decodeStepList = *decodeStepVL[startVL];
for (size_t startPos = 0 ; startPos < m_source.GetSize() ; startPos++)
{
size_t maxSize = m_source.GetSize() - startPos;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; endPos++)
{
CreateTranslationOptionsForRange( decodeStepList, startPos, endPos, true);
}
}
}
VERBOSE(3,"Translation Option Collection\n " << *this << endl);
ProcessUnknownWord(decodeStepVL);
// Prune
Prune();
// future score matrix
CalcFutureScore();
// Cached lex reodering costs
CacheLexReordering();
}
/** create translation options that exactly cover a specific input span.
* Called by CreateTranslationOptions() and ProcessUnknownWord()
* \param decodeStepList list of decoding steps
* \param factorCollection input sentence with all factors
* \param startPos first position in input sentence
* \param lastPos last position in input sentence
* \param adhereTableLimit whether phrase & generation table limits are adhered to
*/
void TranslationOptionCollection::CreateTranslationOptionsForRange(
const DecodeGraph &decodeStepList
, size_t startPos
, size_t endPos
, bool adhereTableLimit)
{
if ((StaticData::Instance().GetXmlInputType() != XmlExclusive) || !HasXmlOptionsOverlappingRange(startPos,endPos))
{
Phrase *sourcePhrase = NULL; // can't initialise with substring, in case it's confusion network
// consult persistent (cross-sentence) cache for stored translation options
bool skipTransOptCreation = false
, useCache = StaticData::Instance().GetUseTransOptCache();
if (useCache)
{
const WordsRange wordsRange(startPos, endPos);
sourcePhrase = new Phrase(m_source.GetSubString(wordsRange));
const TranslationOptionList *transOptList = StaticData::Instance().FindTransOptListInCache(*sourcePhrase);
// is phrase in cache?
if (transOptList != NULL) {
skipTransOptCreation = true;
TranslationOptionList::const_iterator iterTransOpt;
for (iterTransOpt = transOptList->begin() ; iterTransOpt != transOptList->end() ; ++iterTransOpt)
{
TranslationOption *transOpt = new TranslationOption(**iterTransOpt, wordsRange);
Add(transOpt);
}
}
} // useCache
if (!skipTransOptCreation)
{
// partial trans opt stored in here
PartialTranslOptColl* oldPtoc = new PartialTranslOptColl;
size_t totalEarlyPruned = 0;
// initial translation step
list <const DecodeStep* >::const_iterator iterStep = decodeStepList.begin();
const DecodeStep &decodeStep = **iterStep;
static_cast<const DecodeStepTranslation&>(decodeStep).ProcessInitialTranslation
(m_source, *oldPtoc
, startPos, endPos, adhereTableLimit );
// do rest of decode steps
int indexStep = 0;
for (++iterStep ; iterStep != decodeStepList.end() ; ++iterStep)
{
const DecodeStep &decodeStep = **iterStep;
PartialTranslOptColl* newPtoc = new PartialTranslOptColl;
// go thru each intermediate trans opt just created
const vector<TranslationOption*>& partTransOptList = oldPtoc->GetList();
vector<TranslationOption*>::const_iterator iterPartialTranslOpt;
for (iterPartialTranslOpt = partTransOptList.begin() ; iterPartialTranslOpt != partTransOptList.end() ; ++iterPartialTranslOpt)
{
TranslationOption &inputPartialTranslOpt = **iterPartialTranslOpt;
decodeStep.Process(inputPartialTranslOpt
, decodeStep
, *newPtoc
, this
, adhereTableLimit);
}
// last but 1 partial trans not required anymore
totalEarlyPruned += newPtoc->GetPrunedCount();
delete oldPtoc;
oldPtoc = newPtoc;
indexStep++;
} // for (++iterStep
// add to fully formed translation option list
PartialTranslOptColl &lastPartialTranslOptColl = *oldPtoc;
const vector<TranslationOption*>& partTransOptList = lastPartialTranslOptColl.GetList();
vector<TranslationOption*>::const_iterator iterColl;
for (iterColl = partTransOptList.begin() ; iterColl != partTransOptList.end() ; ++iterColl)
{
TranslationOption *transOpt = *iterColl;
transOpt->CalcScore();
Add(transOpt);
}
// storing translation options in persistent cache (kept across sentences)
if (useCache)
{
if (partTransOptList.size() > 0)
{
vector<TranslationOption*> cachedTransOptList = GetTranslationOptionList(startPos, endPos);
vector<TranslationOption*>::iterator iterList;
for (size_t i = 0 ; i < cachedTransOptList.size() ; ++i)
{
cachedTransOptList[i] = new TranslationOption(*cachedTransOptList[i]);
}
StaticData::Instance().AddTransOptListToCache(*sourcePhrase, cachedTransOptList);
}
}
lastPartialTranslOptColl.DetachAll();
totalEarlyPruned += oldPtoc->GetPrunedCount();
delete oldPtoc;
// TRACE_ERR( "Early translation options pruned: " << totalEarlyPruned << endl);
} // if (!skipTransOptCreation)
if (useCache)
delete sourcePhrase;
} // if ((StaticData::Instance().GetXmlInputType() != XmlExclusive) || !HasXmlOptionsOverlappingRange(startPos,endPos))
if ((StaticData::Instance().GetXmlInputType() != XmlPassThrough) && HasXmlOptionsOverlappingRange(startPos,endPos))
{
CreateXmlOptionsForRange(startPos, endPos);
}
}
/** Check if this range overlaps with any XML options. This doesn't need to be an exact match, only an overlap.
* by default, we don't support XML options. subclasses need to override this function.
* called by CreateTranslationOptionsForRange()
* \param startPos first position in input sentence
* \param lastPos last position in input sentence
* \param adhereTableLimit whether phrase & generation table limits are adhered to
*/
bool TranslationOptionCollection::HasXmlOptionsOverlappingRange(size_t, size_t) const {
return false;
}
/** Populates the current Collection with XML options exactly covering the range specified. Default implementation does nothing.
* called by CreateTranslationOptionsForRange()
* \param startPos first position in input sentence
* \param lastPos last position in input sentence
*/
void TranslationOptionCollection::CreateXmlOptionsForRange(size_t, size_t) {
//not implemented for base class
};
/** add translation option to the list
* \param translationOption translation option to be added */
void TranslationOptionCollection::Add(TranslationOption *translationOption)
{
const WordsRange &coverage = translationOption->GetSourceWordsRange();
m_collection[coverage.GetStartPos()][coverage.GetEndPos() - coverage.GetStartPos()].push_back(translationOption);
}
TO_STRING_BODY(TranslationOptionCollection);
inline std::ostream& operator<<(std::ostream& out, const TranslationOptionCollection& coll)
{
size_t size = coll.GetSize();
for (size_t startPos = 0 ; startPos < size ; ++startPos)
{
size_t maxSize = size - startPos;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize ; ++endPos)
{
TranslationOptionList fullList = coll.GetTranslationOptionList(startPos, endPos);
size_t sizeFull = fullList.size();
for (size_t i = 0; i < sizeFull; i++)
{
out << *fullList[i] << std::endl;
}
}
}
//std::vector< std::vector< TranslationOptionList > >::const_iterator i = coll.m_collection.begin();
//size_t j = 0;
//for (; i!=coll.m_collection.end(); ++i) {
//out << "s[" << j++ << "].size=" << i->size() << std::endl;
//}
return out;
}
void TranslationOptionCollection::CacheLexReordering()
{
const std::vector<LexicalReordering*> &lexReorderingModels = StaticData::Instance().GetReorderModels();
std::vector<LexicalReordering*>::const_iterator iterLexreordering;
for (iterLexreordering = lexReorderingModels.begin() ; iterLexreordering != lexReorderingModels.end() ; ++iterLexreordering)
{
LexicalReordering &lexreordering = **iterLexreordering;
for (size_t startPos = 0 ; startPos < m_source.GetSize() ; startPos++)
{
size_t maxSize = m_source.GetSize() - startPos;
size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
maxSize = (maxSize < maxSizePhrase) ? maxSize : maxSizePhrase;
for (size_t endPos = startPos ; endPos < startPos + maxSize; endPos++)
{
TranslationOptionList &transOptList = GetTranslationOptionList( startPos, endPos);
TranslationOptionList::iterator iterTransOpt;
for(iterTransOpt = transOptList.begin() ; iterTransOpt != transOptList.end() ; ++iterTransOpt)
{
TranslationOption &transOpt = **iterTransOpt;
const Phrase *sourcePhrase = transOpt.GetSourcePhrase();
if (sourcePhrase)
{
Score score = lexreordering.GetProb(*sourcePhrase
, transOpt.GetTargetPhrase());
// TODO should have better handling of unknown reordering entries
if (!score.empty())
transOpt.CacheReorderingProb(lexreordering, score);
}
}
}
}
}
}
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