PhiMatcher skip matching

gistfile1.txt

//Compile something like this
//g++ main.cc -o main -O2 -lfst

#include <iostream>
#include <fst/compose.h>
#include <fst/vector-fst.h>


using namespace std;
using namespace fst;



template<class Arc>
void BuildChain(const string& str, const SymbolTable& syms, VectorFst<Arc>* fst, typename Arc::Label phi = -1) {
  typedef typename Arc::StateId S;
  typedef typename Arc::Label L;
  typedef typename Arc::Weight W;
  vector<string> fields;
  fst->DeleteStates();
  S s = fst->AddState();
  fst->SetStart(s);
  for (int i = 0; i != str.size(); ++i) {
    S d = fst->AddState();
    L l = syms.Find(fields[i]);
    fst->AddArc(s, Arc(l, l, W::One(), d));
  }
}

template<class Arc>
void BuildLinearChainAutomata(const string& str, VectorFst<Arc>* ofst, SymbolTable* syms, typename Arc::Label phi = -1) {
  typedef typename Arc::Label L;
  typedef typename Arc::StateId S;
  typedef typename Arc::Weight W;
  char* cstr = new char[str.size() + 1];
  strcpy(cstr, str.c_str());
  vector<char*> fields;
  SplitToVector(cstr, " ", &fields, true);
  S s = ofst->AddState();
  ofst->SetStart(s);
  for (size_t i = 0; i != fields.size(); ++i) {
    S d = ofst->AddState();
    L l = syms->AddSymbol(fields[i]);
    ofst->AddArc(s, Arc(l, l, W::One(), d));
    s = d;
  }
  S d = ofst->AddState();
  ofst->AddArc(s, Arc(0, 0, W::One(), d));
  s = d;
  ofst->SetFinal(s, W::One());
  if (phi != -1) 
    for (S s = 0; s != ofst->NumStates();  ++s) 
      ofst->AddArc(s, Arc(phi, phi, W::One(), s));
  delete[] cstr;
}


template<class Arc>
bool PhiCompose(const Fst<Arc> &fst1,
                const Fst<Arc> &fst2,
                typename Arc::Label phi,
                MutableFst<Arc> *ofst) {
  typedef Fst<Arc> F;
  typedef PhiMatcher<SortedMatcher<F> > M;
  ComposeFstOptions<Arc, M> copts;
  M *matcher = new M(fst1, MATCH_OUTPUT, phi);
  copts.matcher1 = matcher;
  *ofst = ComposeFst<Arc>(fst1, fst2, copts);
  Connect(ofst);
  return ofst->NumStates() > 0;
}


int main(int argc, char** argv) {
  SymbolTable syms("syms");
  syms.AddSymbol("<eps>", 0);
  StdArc::Label phi = syms.AddSymbol("<phi>");
  ifstream ifs(argv[1]);
  if (!ifs.is_open())
    LOG(ERROR) << "Could not open file : " << argv[1];
  string s;
  getline(ifs, s);
  StdVectorFst needle;
  BuildLinearChainAutomata(s, &needle, &syms, phi);
  ArcSort(&needle, OLabelCompare<StdArc>());
  for (; getline(ifs, s); ) {
    StdVectorFst haystack;
    BuildLinearChainAutomata(s, &haystack, &syms);
    StdVectorFst res;
    if (PhiCompose(needle, haystack, phi, &res)) {
      cout << s << endl;
    }
  }
  return 0;
}