text: // See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  //
  // Two FSTS are isomorphic (equal up to state and arc re-ordering) iff their
  // exit status is zero. FSTs should be deterministic when viewed as unweighted
  // automata.
  
  #include <cstring>
  
  #include <memory>
  #include <string>
  
  #include <fst/flags.h>
  #include <fst/log.h>
  #include <fst/script/isomorphic.h>
  
  DECLARE_double(delta);
  
  int fstisomorphic_main(int argc, char **argv) {
    namespace s = fst::script;
    using fst::script::FstClass;
  
    string usage =
        "Two FSTs are isomorphic iff the exit status is zero.\n\n  Usage: ";
    usage += argv[0];
    usage += " in1.fst in2.fst\n";
  
    std::set_new_handler(FailedNewHandler);
    SET_FLAGS(usage.c_str(), &argc, &argv, true);
    if (argc != 3) {
      ShowUsage();
      return 1;
    }
  
    const string in1_name = strcmp(argv[1], "-") == 0 ? "" : argv[1];
    const string in2_name = strcmp(argv[2], "-") == 0 ? "" : argv[2];
  
    if (in1_name.empty() && in2_name.empty()) {
      LOG(ERROR) << argv[0] << ": Can't take both inputs from standard input";
      return 1;
    }
  
    std::unique_ptr<FstClass> ifst1(FstClass::Read(in1_name));
    if (!ifst1) return 1;
  
    std::unique_ptr<FstClass> ifst2(FstClass::Read(in2_name));
    if (!ifst2) return 1;
  
    bool result = s::Isomorphic(*ifst1, *ifst2, FLAGS_delta);
    if (!result) VLOG(1) << "FSTs are not isomorphic";
  
    return result ? 0 : 2;
  }
  