// See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  //
  // Applies an operation to each arc of an FST.
  
  #include <cstring>
  
  #include <memory>
  #include <string>
  
  #include <fst/flags.h>
  #include <fst/log.h>
  #include <fst/script/getters.h>
  #include <fst/script/map.h>
  
  DECLARE_double(delta);
  DECLARE_string(map_type);
  DECLARE_double(power);
  DECLARE_string(weight);
  
  int fstmap_main(int argc, char **argv) {
    namespace s = fst::script;
    using fst::script::FstClass;
    using fst::script::WeightClass;
  
    string usage = "Applies an operation to each arc of an FST.
  
    Usage: ";
    usage += argv[0];
    usage += " [in.fst [out.fst]]
  ";
  
    std::set_new_handler(FailedNewHandler);
    SET_FLAGS(usage.c_str(), &argc, &argv, true);
    if (argc > 3) {
      ShowUsage();
      return 1;
    }
  
    const string in_name = (argc > 1 && strcmp(argv[1], "-") != 0) ? argv[1] : "";
    const string out_name = argc > 2 ? argv[2] : "";
  
    std::unique_ptr<FstClass> ifst(FstClass::Read(in_name));
    if (!ifst) return 1;
  
    s::MapType map_type;
    if (!s::GetMapType(FLAGS_map_type, &map_type)) {
      LOG(ERROR) << argv[0] << ": Unknown or unsupported map type "
                 << FLAGS_map_type;
      return 1;
    }
  
    const auto weight_param =
        !FLAGS_weight.empty()
            ? WeightClass(ifst->WeightType(), FLAGS_weight)
            : (FLAGS_map_type == "times" ? WeightClass::One(ifst->WeightType())
                                         : WeightClass::Zero(ifst->WeightType()));
  
    std::unique_ptr<FstClass> ofst(
        s::Map(*ifst, map_type, FLAGS_delta, FLAGS_power, weight_param));
  
    return !ofst->Write(out_name);
  }