mosesdecoder/moses/ChartTranslationOptions.cpp

/***********************************************************************
 Moses - factored phrase-based language decoder
 Copyright (C) 2010 Hieu Hoang

 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 "ChartTranslationOptions.h"
#include "ChartHypothesis.h"
#include "ChartCellLabel.h"
#include "ChartTranslationOption.h"
#include "InputPath.h"
#include "StaticData.h"

using namespace std;

namespace Moses
{

ChartTranslationOptions::ChartTranslationOptions(const TargetPhraseCollection &targetPhraseColl,
    const StackVec &stackVec,
    const WordsRange &wordsRange,
    float score)
  : m_stackVec(stackVec)
  , m_wordsRange(&wordsRange)
  , m_estimateOfBestScore(score)
{
  TargetPhraseCollection::const_iterator iter;
  for (iter = targetPhraseColl.begin(); iter != targetPhraseColl.end(); ++iter) {
    const TargetPhrase *origTP = *iter;

    boost::shared_ptr<ChartTranslationOption> ptr(new ChartTranslationOption(*origTP));
    m_collection.push_back(ptr);
  }
}

ChartTranslationOptions::~ChartTranslationOptions()
{

}

//! functor to compare (chart) hypotheses by (descending) score
class ChartTranslationOptionScoreOrderer
{
public:
  bool operator()(const boost::shared_ptr<ChartTranslationOption> &transOptA
                  , const boost::shared_ptr<ChartTranslationOption> &transOptB) const {
    const ScoreComponentCollection &scoresA = transOptA->GetScores();
    const ScoreComponentCollection &scoresB = transOptB->GetScores();
    return scoresA.GetWeightedScore() > scoresB.GetWeightedScore();
  }
};

void ChartTranslationOptions::EvaluateWithSourceContext(const InputType &input, const InputPath &inputPath)
{
  SetInputPath(&inputPath);
  if (StaticData::Instance().GetPlaceholderFactor() != NOT_FOUND) {
    CreateSourceRuleFromInputPath();
  }

  CollType::iterator iter;
  for (iter = m_collection.begin(); iter != m_collection.end(); ++iter) {
    ChartTranslationOption &transOpt = **iter;
    transOpt.SetInputPath(&inputPath);
    transOpt.EvaluateWithSourceContext(input, inputPath, m_stackVec);
  }

  // get rid of -inf trans opts
  size_t numDiscard = 0;
  for (size_t i = 0; i < m_collection.size(); ++i) {
    ChartTranslationOption *transOpt = m_collection[i].get();

    if (transOpt->GetScores().GetWeightedScore() == - std::numeric_limits<float>::infinity()) {
      ++numDiscard;
    } else if (numDiscard) {
      m_collection[i - numDiscard] = m_collection[i];
    }
  }

  size_t newSize = m_collection.size() - numDiscard;
  m_collection.resize(newSize);

  // sort if necessary
  const StaticData &staticData = StaticData::Instance();
  if (staticData.RequireSortingAfterSourceContext()) {
    std::sort(m_collection.begin()
              , m_collection.begin() + newSize
              , ChartTranslationOptionScoreOrderer());
  }

}

void ChartTranslationOptions::SetInputPath(const InputPath *inputPath)
{
  CollType::iterator iter;
  for (iter = m_collection.begin(); iter != m_collection.end(); ++iter) {
    ChartTranslationOption &transOpt = **iter;
    transOpt.SetInputPath(inputPath);
  }
}

void ChartTranslationOptions::CreateSourceRuleFromInputPath()
{
  if (m_collection.size() == 0) {
    return;
  }

  const InputPath *inputPath = m_collection.front()->GetInputPath();
  assert(inputPath);
  std::vector<const Word*> &ruleSourceFromInputPath = inputPath->AddRuleSourceFromInputPath();

  size_t chartCellIndex = 0;
  const ChartCellLabel *chartCellLabel = (chartCellIndex < m_stackVec.size()) ? m_stackVec[chartCellIndex] : NULL;

  size_t ind = 0;
  for (size_t sourcePos = m_wordsRange->GetStartPos(); sourcePos <= m_wordsRange->GetEndPos(); ++sourcePos, ++ind) {
    if (chartCellLabel) {
      if (sourcePos == chartCellLabel->GetCoverage().GetEndPos()) {
        // end of child range. push an empty word to denote non-term
        ruleSourceFromInputPath.push_back(NULL);
        ++chartCellIndex;
        chartCellLabel = (chartCellIndex < m_stackVec.size()) ? m_stackVec[chartCellIndex] : NULL;
      } else if (sourcePos >= chartCellLabel->GetCoverage().GetStartPos()) {
        // in the range of child hypo. do nothing
      } else {
        // not yet reached child range. add word
        ruleSourceFromInputPath.push_back(&inputPath->GetPhrase().GetWord(ind));
      }
    } else {
      // no child in sight. add word
      ruleSourceFromInputPath.push_back(&inputPath->GetPhrase().GetWord(ind));
    }
  }

  // save it to each trans opt
  CollType::iterator iter;
  for (iter = m_collection.begin(); iter != m_collection.end(); ++iter) {
    ChartTranslationOption &transOpt = **iter;
    transOpt.SetSourceRuleFromInputPath(&ruleSourceFromInputPath);
  }

}

std::ostream& operator<<(std::ostream &out, const ChartTranslationOptions &obj)
{
  for (size_t i = 0; i < obj.m_collection.size(); ++i) {
    const ChartTranslationOption &transOpt = *obj.m_collection[i];
    out << transOpt << endl;
  }

  return out;
}

}