mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-11-10 10:59:21 +03:00
114 lines
3.6 KiB
C++
114 lines
3.6 KiB
C++
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#include "DistortionScoreProducer.h"
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#include "FFState.h"
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#include "moses/WordsRange.h"
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#include "moses/StaticData.h"
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#include "moses/Hypothesis.h"
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using namespace std;
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namespace Moses
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{
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struct DistortionState_traditional : public FFState {
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WordsRange range;
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int first_gap;
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DistortionState_traditional(const WordsRange& wr, int fg) : range(wr), first_gap(fg) {}
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int Compare(const FFState& other) const {
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const DistortionState_traditional& o =
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static_cast<const DistortionState_traditional&>(other);
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if (range.GetEndPos() < o.range.GetEndPos()) return -1;
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if (range.GetEndPos() > o.range.GetEndPos()) return 1;
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return 0;
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}
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};
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std::vector<const DistortionScoreProducer*> DistortionScoreProducer::s_staticColl;
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DistortionScoreProducer::DistortionScoreProducer(const std::string &line)
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: StatefulFeatureFunction(1, line)
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{
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s_staticColl.push_back(this);
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ReadParameters();
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}
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const FFState* DistortionScoreProducer::EmptyHypothesisState(const InputType &input) const
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{
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// fake previous translated phrase start and end
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size_t start = NOT_FOUND;
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size_t end = NOT_FOUND;
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if (input.m_frontSpanCoveredLength > 0) {
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// can happen with --continue-partial-translation
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start = 0;
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end = input.m_frontSpanCoveredLength -1;
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}
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return new DistortionState_traditional(
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WordsRange(start, end),
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NOT_FOUND);
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}
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float DistortionScoreProducer::CalculateDistortionScore(const Hypothesis& hypo,
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const WordsRange &prev, const WordsRange &curr, const int FirstGap)
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{
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if(!StaticData::Instance().UseEarlyDistortionCost()) {
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return - (float) hypo.GetInput().ComputeDistortionDistance(prev, curr);
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} else {
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/* Pay distortion score as soon as possible, from Moore and Quirk MT Summit 2007
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Definitions:
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S : current source range
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S' : last translated source phrase range
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S'' : longest fully-translated initial segment
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*/
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int prefixEndPos = (int)FirstGap-1;
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if((int)FirstGap==-1)
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prefixEndPos = -1;
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// case1: S is adjacent to S'' => return 0
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if ((int) curr.GetStartPos() == prefixEndPos+1) {
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IFVERBOSE(4) std::cerr<< "MQ07disto:case1" << std::endl;
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return 0;
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}
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// case2: S is to the left of S' => return 2(length(S))
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if ((int) curr.GetEndPos() < (int) prev.GetEndPos()) {
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IFVERBOSE(4) std::cerr<< "MQ07disto:case2" << std::endl;
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return (float) -2*(int)curr.GetNumWordsCovered();
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}
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// case3: S' is a subsequence of S'' => return 2(nbWordBetween(S,S'')+length(S))
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if ((int) prev.GetEndPos() <= prefixEndPos) {
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IFVERBOSE(4) std::cerr<< "MQ07disto:case3" << std::endl;
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int z = (int)curr.GetStartPos()-prefixEndPos - 1;
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return (float) -2*(z + (int)curr.GetNumWordsCovered());
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}
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// case4: otherwise => return 2(nbWordBetween(S,S')+length(S))
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IFVERBOSE(4) std::cerr<< "MQ07disto:case4" << std::endl;
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return (float) -2*((int)curr.GetNumWordsBetween(prev) + (int)curr.GetNumWordsCovered());
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}
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}
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FFState* DistortionScoreProducer::EvaluateWhenApplied(
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const Hypothesis& hypo,
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const FFState* prev_state,
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ScoreComponentCollection* out) const
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{
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const DistortionState_traditional* prev = static_cast<const DistortionState_traditional*>(prev_state);
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const float distortionScore = CalculateDistortionScore(
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hypo,
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prev->range,
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hypo.GetCurrSourceWordsRange(),
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prev->first_gap);
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out->PlusEquals(this, distortionScore);
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DistortionState_traditional* res = new DistortionState_traditional(
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hypo.GetCurrSourceWordsRange(),
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hypo.GetWordsBitmap().GetFirstGapPos());
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return res;
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}
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}
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