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()); } }