src/include/fst/script/register.h

// 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: jpr@google.com (Jake Ratkiewicz)

#ifndef FST_SCRIPT_REGISTER_H_
#define FST_SCRIPT_REGISTER_H_

#include <string>

#include <fst/generic-register.h>
#include <fst/script/fst-class.h>
#include <fst/script/weight-class.h>

// Holds methods and classes responsible for maintaining
// the register for FstClass arc types.

namespace fst {
namespace script {

//
// Registers for reading and converting various kinds of FST classes.
//

// This class definition is to avoid a nested class definition inside
// the IORegistration struct.
template<class Reader, class Creator, class Converter>
struct FstClassRegEntry {
  Reader reader;
  Creator creator;
  Converter converter;

  FstClassRegEntry(Reader r, Creator cr, Converter co) :
      reader(r), creator(cr), converter(co) { }
  FstClassRegEntry() : reader(0), creator(0), converter(0) { }
};

template<class Reader, class Creator, class Converter>
class FstClassIORegister
    : public GenericRegister<string,
                             FstClassRegEntry<Reader, Creator, Converter>,
                             FstClassIORegister<Reader, Creator,
                                                Converter> > {
 public:
  Reader GetReader(const string &arc_type) const {
    return this->GetEntry(arc_type).reader;
  }

  Creator GetCreator(const string &arc_type) const {
    return this->GetEntry(arc_type).creator;
  }

  Converter GetConverter(const string &arc_type) const {
    return this->GetEntry(arc_type).converter;
  }

 protected:
  virtual string ConvertKeyToSoFilename(
      const string& key) const {
    string legal_type(key);
    ConvertToLegalCSymbol(&legal_type);

    return legal_type + "-arc.so";
  }
};

//
// Struct containing everything needed to register a particular type
// of FST class (e.g. a plain FstClass, or a MutableFstClass, etc)
//
template<class FstClassType>
struct IORegistration {
  typedef FstClassType *(*Reader)(istream &stream,
                                  const FstReadOptions &opts);

  typedef FstClassImplBase *(*Creator)();
  typedef FstClassImplBase *(*Converter)(const FstClass &other);

  typedef FstClassRegEntry<Reader, Creator, Converter> Entry;

  // FST class Register
  typedef FstClassIORegister<Reader, Creator, Converter> Register;

  // FST class Register-er
  typedef GenericRegisterer<FstClassIORegister<Reader, Creator, Converter> >
    Registerer;
};


//
// REGISTRATION MACROS
//

#define REGISTER_FST_CLASS(Class, Arc)                                  \
  static IORegistration<Class>::Registerer Class ## _ ## Arc ## _registerer( \
      Arc::Type(),                                                      \
      IORegistration<Class>::Entry(Class::Read<Arc>,                    \
                                   Class::Create<Arc>,                  \
                                   Class::Convert<Arc>))

#define REGISTER_FST_CLASSES(Arc)               \
  REGISTER_FST_CLASS(FstClass, Arc);            \
  REGISTER_FST_CLASS(MutableFstClass, Arc);     \
  REGISTER_FST_CLASS(VectorFstClass, Arc);

}  // namespace script
}  // namespace fst

#endif  // FST_SCRIPT_REGISTER_H_