Score.cpp

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//Copyright (c) 2012, University of Cambridge
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#include "Score.h"

Sentence GetBestHypothesisTokens (const
                                  fst::VectorFst<fst::ArcTpl<FeatureWeight> >* fst) {
  fst::VectorFst<fst::ArcTpl<FeatureWeight> > fsttmp1;
  fst::ShortestPath (*fst, &fsttmp1);
  fst::Project (&fsttmp1, fst::PROJECT_INPUT);
  fst::RmEpsilon (&fsttmp1);
  fst::TopSort (&fsttmp1);
  Sentence best;
  for (fst::StateIterator<fst::VectorFst<fst::ArcTpl<FeatureWeight> > > si (
         fsttmp1);
       !si.Done(); si.Next() ) {
    for (fst::ArcIterator<fst::VectorFst<fst::ArcTpl<FeatureWeight> > > ai (fsttmp1,
         si.Value() ); !ai.Done(); ai.Next() ) {
      best.push_back (ai.Value().ilabel);
    }
  }
  return best;
}

Sentence GetBestHypothesis (const TupleArcFst* fst, const PARAMS& lambda) {
  fst::VectorFst<fst::ArcTpl<FeatureWeight> > * fsttmp1 = new fst::VectorFst <
  fst::ArcTpl<FeatureWeight> > ();
  fst::DotProductMap<double> m (lambda);
  Map (
    *fst,
    fsttmp1,
    fst::GeneralMapper<TupleArc, fst::ArcTpl<FeatureWeight>, fst::DotProductMap<double> >
    (
      m) );
  fst::VectorFst<fst::ArcTpl<FeatureWeight> > *fsttmp2 = new fst::VectorFst <
  fst::ArcTpl<FeatureWeight> >;
  ShortestPath (*fsttmp1, fsttmp2);
  delete fsttmp1;
  Sentence h = GetBestHypothesisTokens (fsttmp2);
  delete fsttmp2;
  int offset;
  h.size() < 2 ? offset = 0 : offset = 1;
  Sentence s = NGram (h.begin() + offset,
                      h.end() - offset); // Trim sentence start and end markers from hypothesis
  return s;
}