// See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  
  #include <fst/compat.h>
  #include <fst/extensions/linear/linear-fst.h>
  #include <fst/extensions/linear/loglinear-apply.h>
  #include <fst/vector-fst.h>
  
  #include <fst/flags.h>
  #include <fst/log.h>
  
  DEFINE_bool(normalize, true, "Normalize to get posterior");
  
  int main(int argc, char **argv) {
    string usage =
        "Applies an FST to another FST, treating the second as a log-linear "
        "model.
  
    "
        "Usage: ";
    usage += argv[0];
    usage += " in.fst linear.fst [out.fst]
  ";
  
    std::set_new_handler(FailedNewHandler);
    SET_FLAGS(usage.c_str(), &argc, &argv, true);
    if (argc < 3 || argc > 4) {
      ShowUsage();
      return 1;
    }
  
    string in_name = strcmp(argv[1], "-") != 0 ? argv[1] : "";
    string linear_name = (argc > 2 && (strcmp(argv[2], "-") != 0)) ? argv[2] : "";
    string out_name = argc > 3 ? argv[3] : "";
  
    if (in_name.empty() && linear_name.empty()) {
      LOG(ERROR) << argv[0] << ": Can't take both inputs from standard input.";
      return 1;
    }
  
    fst::StdFst *ifst1 = fst::StdFst::Read(in_name);
    if (!ifst1) return 1;
  
    fst::StdFst *ifst2 = fst::StdFst::Read(linear_name);
    if (!ifst2) return 1;
  
    fst::StdVectorFst ofst;
  
    LogLinearApply(*ifst1, *ifst2, &ofst, FLAGS_normalize);
  
    ofst.Write(out_name);
  
    return 0;
  }