// See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  
  #include <fst/script/fst-class.h>
  #include <fst/script/difference.h>
  #include <fst/script/script-impl.h>
  
  namespace fst {
  namespace script {
  
  void Difference(const FstClass &ifst1, const FstClass &ifst2,
                  MutableFstClass *ofst, const ComposeOptions &opts) {
    if (!internal::ArcTypesMatch(ifst1, ifst2, "Difference") ||
        !internal::ArcTypesMatch(*ofst, ifst1, "Difference")) {
      ofst->SetProperties(kError, kError);
      return;
    }
    DifferenceArgs args(ifst1, ifst2, ofst, opts);
    Apply<Operation<DifferenceArgs>>("Difference", ifst1.ArcType(), &args);
  }
  
  REGISTER_FST_OPERATION(Difference, StdArc, DifferenceArgs);
  REGISTER_FST_OPERATION(Difference, LogArc, DifferenceArgs);
  REGISTER_FST_OPERATION(Difference, Log64Arc, DifferenceArgs);
  
  }  // namespace script
  }  // namespace fst