src/bin/fstshortestpath.cc

// fstshortestpath.cc

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Copyright 2005-2010 Google, Inc.
// Author: allauzen@google.com (Cyril Allauzen)
// Modified: jpr@google.com (Jake Ratkiewicz) to use FstClass
//
// \file
// Find shortest path(s) in an FST.

#include <fst/script/shortest-path.h>

DEFINE_double(delta, fst::kDelta, "Comparison/quantization delta");
DEFINE_int64(nshortest, 1, "Return N-shortest paths");
DEFINE_bool(unique, false, "Return unique strings");
DEFINE_string(weight, "", "Weight threshold");
DEFINE_int64(nstate, fst::kNoStateId, "State number threshold");
DEFINE_string(queue_type, "auto", "Queue type: one of \"auto\", "
              "\"fifo\", \"lifo\", \"shortest\', \"state\", \"top\"");

int main(int argc, char **argv) {
  namespace s = fst::script;
  using fst::script::FstClass;
  using fst::script::MutableFstClass;
  using fst::script::VectorFstClass;
  using fst::script::WeightClass;

  string usage = "Finds shortest path(s) in an FST.\n\n  Usage: ";
  usage += argv[0];
  usage += " [in.fst [out.fst]]\n";


  std::set_new_handler(FailedNewHandler);
  SET_FLAGS(usage.c_str(), &argc, &argv, true);
  if (argc > 3) {
    ShowUsage();
    return 1;
  }

  string in_fname = (argc > 1 && (strcmp(argv[1], "-") != 0)) ? argv[1] : "";
  string out_fname = argc > 2 ? argv[2] : "";

  FstClass *ifst = FstClass::Read(in_fname);
  if (!ifst) return 1;

  WeightClass weight_threshold = FLAGS_weight.empty() ?
      WeightClass::Zero() :
      WeightClass(ifst->WeightType(), FLAGS_weight);

  VectorFstClass ofst(ifst->ArcType());
  vector<WeightClass> distance;

  fst::QueueType qt;

  if (FLAGS_queue_type == "auto") {
    qt = fst::AUTO_QUEUE;
  } else if (FLAGS_queue_type == "fifo") {
    qt = fst::FIFO_QUEUE;
  } else if (FLAGS_queue_type == "lifo") {
    qt = fst::LIFO_QUEUE;
  } else if (FLAGS_queue_type == "shortest") {
    qt = fst::SHORTEST_FIRST_QUEUE;
  } else if (FLAGS_queue_type == "state") {
    qt = fst::STATE_ORDER_QUEUE;
  } else if (FLAGS_queue_type == "top") {
    qt = fst::TOP_ORDER_QUEUE;
  } else {
    LOG(ERROR) << "Unknown or unsupported queue type: " << FLAGS_queue_type;
    return 1;
  }

  s::ShortestPathOptions opts(
      qt, FLAGS_nshortest, FLAGS_unique, false, FLAGS_delta,
      false, weight_threshold, FLAGS_nstate);

  s::ShortestPath(*ifst, &ofst, &distance, opts);

  ofst.Write(out_fname);

  return 0;
}