mosesdecoder/moses/DummyScoreProducers.cpp
2012-11-12 19:56:18 +00:00

141 lines
4.1 KiB
C++

// $Id$
#include "util/check.hh"
#include "FFState.h"
#include "StaticData.h"
#include "DummyScoreProducers.h"
#include "WordsRange.h"
#include "TranslationOption.h"
namespace Moses
{
struct DistortionState_traditional : public FFState {
WordsRange range;
int first_gap;
DistortionState_traditional(const WordsRange& wr, int fg) : range(wr), first_gap(fg) {}
int Compare(const FFState& other) const {
const DistortionState_traditional& o =
static_cast<const DistortionState_traditional&>(other);
if (range.GetEndPos() < o.range.GetEndPos()) return -1;
if (range.GetEndPos() > o.range.GetEndPos()) return 1;
return 0;
}
};
const FFState* DistortionScoreProducer::EmptyHypothesisState(const InputType &input) const
{
// fake previous translated phrase start and end
size_t start = NOT_FOUND;
size_t end = NOT_FOUND;
if (input.m_frontSpanCoveredLength > 0) {
// can happen with --continue-partial-translation
start = 0;
end = input.m_frontSpanCoveredLength -1;
}
return new DistortionState_traditional(
WordsRange(start, end),
NOT_FOUND);
}
std::string DistortionScoreProducer::GetScoreProducerWeightShortName(unsigned) const
{
return "d";
}
float DistortionScoreProducer::CalculateDistortionScore(const Hypothesis& hypo,
const WordsRange &prev, const WordsRange &curr, const int FirstGap) const
{
if(!StaticData::Instance().UseEarlyDistortionCost()) {
return - (float) hypo.GetInput().ComputeDistortionDistance(prev, curr);
}
else {
/* Pay distortion score as soon as possible, from Moore and Quirk MT Summit 2007
Definitions:
S : current source range
S' : last translated source phrase range
S'' : longest fully-translated initial segment
*/
int prefixEndPos = (int)FirstGap-1;
if((int)FirstGap==-1)
prefixEndPos = -1;
// case1: S is adjacent to S'' => return 0
if ((int) curr.GetStartPos() == prefixEndPos+1) {
IFVERBOSE(4) std::cerr<< "MQ07disto:case1" << std::endl;
return 0;
}
// case2: S is to the left of S' => return 2(length(S))
if ((int) curr.GetEndPos() < (int) prev.GetEndPos()) {
IFVERBOSE(4) std::cerr<< "MQ07disto:case2" << std::endl;
return (float) -2*(int)curr.GetNumWordsCovered();
}
// case3: S' is a subsequence of S'' => return 2(nbWordBetween(S,S'')+length(S))
if ((int) prev.GetEndPos() <= prefixEndPos) {
IFVERBOSE(4) std::cerr<< "MQ07disto:case3" << std::endl;
int z = (int)curr.GetStartPos()-prefixEndPos - 1;
return (float) -2*(z + (int)curr.GetNumWordsCovered());
}
// case4: otherwise => return 2(nbWordBetween(S,S')+length(S))
IFVERBOSE(4) std::cerr<< "MQ07disto:case4" << std::endl;
return (float) -2*((int)curr.GetNumWordsBetween(prev) + (int)curr.GetNumWordsCovered());
}
}
FFState* DistortionScoreProducer::Evaluate(
const Hypothesis& hypo,
const FFState* prev_state,
ScoreComponentCollection* out) const
{
const DistortionState_traditional* prev = static_cast<const DistortionState_traditional*>(prev_state);
const float distortionScore = CalculateDistortionScore(
hypo,
prev->range,
hypo.GetCurrSourceWordsRange(),
prev->first_gap);
out->PlusEquals(this, distortionScore);
DistortionState_traditional* res = new DistortionState_traditional(
hypo.GetCurrSourceWordsRange(),
hypo.GetWordsBitmap().GetFirstGapPos());
return res;
}
std::string WordPenaltyProducer::GetScoreProducerWeightShortName(unsigned) const
{
return "w";
}
void WordPenaltyProducer::Evaluate(
const PhraseBasedFeatureContext& context,
ScoreComponentCollection* out) const
{
const TargetPhrase& tp = context.GetTargetPhrase();
out->PlusEquals(this, -static_cast<float>(tp.GetSize()));
}
std::string UnknownWordPenaltyProducer::GetScoreProducerWeightShortName(unsigned) const
{
return "u";
}
bool UnknownWordPenaltyProducer::ComputeValueInTranslationOption() const
{
return true;
}
std::string MetaFeatureProducer::GetScoreProducerWeightShortName(unsigned) const
{
return "m"+m_shortName;
}
}