farconvert-main.cc

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// Copyright 2005-2024 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.
//
// Converts FST and container type of FARs.

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

#include <fst/flags.h>
#include <fst/log.h>
#include <fst/extensions/far/far-class.h>
#include <fst/extensions/far/far.h>
#include <fst/extensions/far/farscript.h>
#include <fst/extensions/far/getters.h>
#include <fst/util.h>
#include <fst/script/arg-packs.h>

DECLARE_string(far_type);
DECLARE_string(fst_type);

int farconvert_main(int argc, char **argv) {
  namespace s = fst::script;
  using fst::script::FarReaderClass;
  using fst::script::FarWriterClass;

  std::string usage = "Converts FST and container types.\n\n  Usage: ";
  usage += argv[0];
  usage += " [in.far [out.far]]\n";

  SET_FLAGS(usage.c_str(), &argc, &argv, true);
  s::ExpandArgs(argc, argv, &argc, &argv);

  if (argc > 3) {
    ShowUsage();
    return 1;
  }

  // No args: read from stdin and write to stdout.
  // One arg: read from in.far and write to stdout.
  // Note that only STList can be written to stdout.
  const std::string in_name =
      argc > 1 && std::strcmp(argv[1], "-") != 0 ? argv[1] : "";
  const std::string out_name =
      argc > 2 && std::strcmp(argv[2], "-") != 0 ? argv[2] : "";

  fst::FarType far_type;
  if (!s::GetFarType(FST_FLAGS_far_type, &far_type)) {
    LOG(ERROR) << "Unknown --far_type " << FST_FLAGS_far_type;
    return 1;
  }

  std::unique_ptr<FarReaderClass> reader(FarReaderClass::Open(in_name));
  if (!reader) return 1;

  // This uses a different meaning of far_type; since DEFAULT means "same as
  // input", we must determine the input FarType.
  if (far_type == fst::FarType::DEFAULT) far_type = reader->Type();

  const auto arc_type = reader->ArcType();
  if (arc_type.empty()) return 1;

  std::unique_ptr<FarWriterClass> writer(
      FarWriterClass::Create(out_name, arc_type, far_type));
  if (!writer) return 1;

  // An unspecified fst_type entails that the input FST types are preserved.
  s::Convert(*reader, *writer, FST_FLAGS_fst_type);

  if (reader->Error()) {
    FSTERROR() << "Error reading FAR: " << in_name;
    return 1;
  }
  if (writer->Error()) {
    FSTERROR() << "Error writing FAR: " << out_name;
    return 1;
  }

  return 0;
}