mosesdecoder/moses/FF/ConstrainedDecoding.cpp

#include "ConstrainedDecoding.h"
#include "moses/Hypothesis.h"
#include "moses/Manager.h"
#include "moses/ChartHypothesis.h"
#include "moses/ChartManager.h"
#include "moses/StaticData.h"
#include "moses/InputFileStream.h"
#include "moses/Util.h"
#include "util/exception.hh"

using namespace std;

namespace Moses
{
ConstrainedDecodingState::ConstrainedDecodingState(const Hypothesis &hypo)
{
	hypo.GetOutputPhrase(m_outputPhrase);
}

ConstrainedDecodingState::ConstrainedDecodingState(const ChartHypothesis &hypo)
{
	hypo.GetOutputPhrase(m_outputPhrase);
}

int ConstrainedDecodingState::Compare(const FFState& other) const
{
	const ConstrainedDecodingState &otherFF = static_cast<const ConstrainedDecodingState&>(other);
	bool ret = 	m_outputPhrase.Compare(otherFF.m_outputPhrase);
	return ret;
}

//////////////////////////////////////////////////////////////////
void ConstrainedDecoding::Load()
{
	const StaticData &staticData = StaticData::Instance();
	bool addBeginEndWord = (staticData.GetSearchAlgorithm() == ChartDecoding) || (staticData.GetSearchAlgorithm() == ChartIncremental);

	InputFileStream constraintFile(m_path);
	std::string line;
	long sentenceID = staticData.GetStartTranslationId() - 1;
	while (getline(constraintFile, line)) {
	  vector<string> vecStr = Tokenize(line, "\t");

	  Phrase phrase(0);
	  if (vecStr.size() == 1) {
		sentenceID++;
		phrase.CreateFromString(Output, staticData.GetOutputFactorOrder(), vecStr[0], staticData.GetFactorDelimiter(), NULL);
	  } else if (vecStr.size() == 2) {
		sentenceID = Scan<long>(vecStr[0]);
		phrase.CreateFromString(Output, staticData.GetOutputFactorOrder(), vecStr[1], staticData.GetFactorDelimiter(), NULL);
	  } else {
		CHECK(false);
	  }

	  if (addBeginEndWord) {
		phrase.InitStartEndWord();
	  }
	  m_constraints.insert(make_pair(sentenceID,phrase));

	}
}

std::vector<float> ConstrainedDecoding::DefaultWeights() const
{
	CHECK(m_numScoreComponents == 1);
	vector<float> ret(1, 1);
	return ret;
}

template <class H, class M>
const Phrase *GetConstraint(const std::map<long,Phrase> &constraints, const H &hypo)
{
	const M &mgr = hypo.GetManager();
	const InputType &input = mgr.GetSource();
	long id = input.GetTranslationId();

	map<long,Phrase>::const_iterator iter;
	iter = constraints.find(id);

	if (iter == constraints.end()) {
		return NULL;
	}
	else {
		return &iter->second;
	}
}

FFState* ConstrainedDecoding::Evaluate(
  const Hypothesis& hypo,
  const FFState* prev_state,
  ScoreComponentCollection* accumulator) const
{
	const Phrase *ref = GetConstraint<Hypothesis, Manager>(m_constraints, hypo);
	CHECK(ref);

	ConstrainedDecodingState *ret = new ConstrainedDecodingState(hypo);
	const Phrase &outputPhrase = ret->GetPhrase();

	size_t searchPos = ref->Find(outputPhrase, m_maxUnknowns);

	float score;
	if (hypo.IsSourceCompleted()) {
		// translated entire sentence.
		score = (searchPos == 0) && (ref->GetSize() == outputPhrase.GetSize())
						? 0 : - std::numeric_limits<float>::infinity();
	}
	else {
		score = (searchPos != NOT_FOUND) ? 0 : - std::numeric_limits<float>::infinity();
	}

	accumulator->PlusEquals(this, score);

	return ret;
}

FFState* ConstrainedDecoding::EvaluateChart(
  const ChartHypothesis &hypo,
  int /* featureID - used to index the state in the previous hypotheses */,
  ScoreComponentCollection* accumulator) const
{
	const Phrase *ref = GetConstraint<ChartHypothesis, ChartManager>(m_constraints, hypo);
	CHECK(ref);

	const ChartManager &mgr = hypo.GetManager();
	const Sentence &source = static_cast<const Sentence&>(mgr.GetSource());

	ConstrainedDecodingState *ret = new ConstrainedDecodingState(hypo);
	const Phrase &outputPhrase = ret->GetPhrase();
	size_t searchPos = ref->Find(outputPhrase, m_maxUnknowns);

	float score;
	if (hypo.GetCurrSourceRange().GetStartPos() == 0 &&
		hypo.GetCurrSourceRange().GetEndPos() == source.GetSize() - 1) {
		// translated entire sentence.
		score = (searchPos == 0) && (ref->GetSize() == outputPhrase.GetSize())
						? 0 : - std::numeric_limits<float>::infinity();
	}
	else {
		score = (searchPos != NOT_FOUND) ? 0 : - std::numeric_limits<float>::infinity();
	}

	accumulator->PlusEquals(this, score);

	return ret;
}

void ConstrainedDecoding::SetParameter(const std::string& key, const std::string& value)
{
  if (key == "path") {
	  m_path = value;
  }
  else if (key == "max-unknowns") {
	  m_maxUnknowns = Scan<int>(value);
  }
  else {
    StatefulFeatureFunction::SetParameter(key, value);
  }
}

}