fstprune-main.cc

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// Copyright 2005-2020 Google LLC
//
// 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.
//
// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
//
// Prunes states and arcs of an FST w.r.t. the shortest path weight.

#include <cstring>
#include <memory>
#include <string>

#include <fst/flags.h>
#include <fst/script/prune.h>

DECLARE_double(delta);
DECLARE_int64(nstate);
DECLARE_string(weight);

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

  std::string usage = "Prunes states and arcs of 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;
  }

  const std::string in_name =
      (argc > 1 && strcmp(argv[1], "-") != 0) ? argv[1] : "";
  const std::string out_name =
      (argc > 2 && strcmp(argv[2], "-") != 0) ? argv[2] : "";

  std::unique_ptr<MutableFstClass> fst(MutableFstClass::Read(in_name, true));
  if (!fst) return 1;

  const auto weight_threshold =
      FST_FLAGS_weight.empty()
          ? WeightClass::Zero(fst->WeightType())
          : WeightClass(fst->WeightType(), FST_FLAGS_weight);

  s::Prune(fst.get(), weight_threshold, FST_FLAGS_nstate,
           FST_FLAGS_delta);

  return !fst->Write(out_name);
}