// See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  
  #ifndef FST_SCRIPT_ARCITERATOR_CLASS_H_
  #define FST_SCRIPT_ARCITERATOR_CLASS_H_
  
  #include <memory>
  #include <utility>
  
  #include <fst/fstlib.h>
  #include <fst/script/fst-class.h>
  
  // Scripting API support for ArcIterator.
  //
  // A call to Value() causes the underlying arc to be used to construct the
  // associated ArcClass.
  
  namespace fst {
  namespace script {
  
  // Non-mutable arc iterators.
  
  // Virtual interface implemented by each concrete ArcIteratorImpl<F>.
  class ArcIteratorImplBase {
   public:
    virtual bool Done() const = 0;
    virtual uint32 Flags() const = 0;
    virtual void Next() = 0;
    virtual size_t Position() const = 0;
    virtual void Reset() = 0;
    virtual void Seek(size_t a) = 0;
    virtual void SetFlags(uint32 flags, uint32 mask) = 0;
    virtual ArcClass Value() const = 0;
    virtual ~ArcIteratorImplBase() {}
  };
  
  // Templated implementation.
  template <class Arc>
  class ArcIteratorClassImpl : public ArcIteratorImplBase {
   public:
    explicit ArcIteratorClassImpl(const Fst<Arc> &fst, int64 s)
        : aiter_(fst, s) {}
  
    bool Done() const final { return aiter_.Done(); }
  
    uint32 Flags() const final { return aiter_.Flags(); }
  
    void Next() final { aiter_.Next(); }
  
    size_t Position() const final { return aiter_.Position(); }
  
    void Reset() final { aiter_.Reset(); }
  
    void Seek(size_t a) final { aiter_.Seek(a); }
  
    void SetFlags(uint32 flags, uint32 mask) final {
      aiter_.SetFlags(flags, mask);
    }
  
    // This is returned by value because it has not yet been constructed, and
    // is likely to participate in return-value optimization.
    ArcClass Value() const final { return ArcClass(aiter_.Value()); }
  
    ~ArcIteratorClassImpl() final {}
  
   private:
    ArcIterator<Fst<Arc>> aiter_;
  };
  
  class ArcIteratorClass;
  
  using InitArcIteratorClassArgs =
      std::tuple<const FstClass &, int64, ArcIteratorClass *>;
  
  // Untemplated user-facing class holding a templated pimpl.
  class ArcIteratorClass {
   public:
    ArcIteratorClass(const FstClass &fst, int64 s);
  
    template <class Arc>
    ArcIteratorClass(const Fst<Arc> &fst, int64 s)
        : impl_(new ArcIteratorClassImpl<Arc>(fst, s)) {}
  
    bool Done() const { return impl_->Done(); }
  
    uint32 Flags() const { return impl_->Flags(); }
  
    void Next() { impl_->Next(); }
  
    size_t Position() const { return impl_->Position(); }
  
    void Reset() { impl_->Reset(); }
  
    void Seek(size_t a) { impl_->Seek(a); }
  
    void SetFlags(uint32 flags, uint32 mask) { impl_->SetFlags(flags, mask); }
  
    ArcClass Value() const { return impl_->Value(); }
  
    template <class Arc>
    friend void InitArcIteratorClass(InitArcIteratorClassArgs *args);
  
   private:
    std::unique_ptr<ArcIteratorImplBase> impl_;
  };
  
  template <class Arc>
  void InitArcIteratorClass(InitArcIteratorClassArgs *args) {
    const Fst<Arc> &fst = *(std::get<0>(*args).GetFst<Arc>());
    std::get<2>(*args)->impl_.reset(
        new ArcIteratorClassImpl<Arc>(fst, std::get<1>(*args)));
  }
  
  // Mutable arc iterators.
  
  // Virtual interface implemented by each concrete MutableArcIteratorImpl<F>.
  class MutableArcIteratorImplBase : public ArcIteratorImplBase {
   public:
    virtual void SetValue(const ArcClass &) = 0;
  
    ~MutableArcIteratorImplBase() override {}
  };
  
  // Templated implementation.
  template <class Arc>
  class MutableArcIteratorClassImpl
      : public MutableArcIteratorImplBase {
   public:
    explicit MutableArcIteratorClassImpl(MutableFst<Arc> *fst, int64 s)
        : aiter_(fst, s) {}
  
    bool Done() const final { return aiter_.Done(); }
  
    uint32 Flags() const final { return aiter_.Flags(); }
  
    void Next() final { aiter_.Next(); }
  
    size_t Position() const final { return aiter_.Position(); }
  
    void Reset() final { aiter_.Reset(); }
  
    void Seek(size_t a) final { aiter_.Seek(a); }
  
    void SetFlags(uint32 flags, uint32 mask) final {
      aiter_.SetFlags(flags, mask);
    }
  
    void SetValue(const Arc &arc) { aiter_.SetValue(arc); }
  
    void SetValue(const ArcClass &ac) final { aiter_.SetValue(ac.GetArc<Arc>()); }
  
    // This is returned by value because it has not yet been constructed, and
    // is likely to participate in return-value optimization.
    ArcClass Value() const final { return ArcClass(aiter_.Value()); }
  
    ~MutableArcIteratorClassImpl() override {}
  
   private:
    MutableArcIterator<MutableFst<Arc>> aiter_;
  };
  
  class MutableArcIteratorClass;
  
  using InitMutableArcIteratorClassArgs =
      std::tuple<MutableFstClass *, int64, MutableArcIteratorClass *>;
  
  // Untemplated user-facing class holding a templated pimpl.
  class MutableArcIteratorClass {
   public:
    MutableArcIteratorClass(MutableFstClass *fst, int64 s);
  
    template <class Arc>
    MutableArcIteratorClass(MutableFst<Arc> *fst, int64 s)
        : impl_(new MutableArcIteratorClassImpl<Arc>(fst, s)) {}
  
    bool Done() const { return impl_->Done(); }
  
    uint32 Flags() const { return impl_->Flags(); }
  
    void Next() { impl_->Next(); }
  
    size_t Position() const { return impl_->Position(); }
  
    void Reset() { impl_->Reset(); }
  
    void Seek(size_t a) { impl_->Seek(a); }
  
    void SetFlags(uint32 flags, uint32 mask) { impl_->SetFlags(flags, mask); }
  
    void SetValue(const ArcClass &ac) { impl_->SetValue(ac); }
  
    ArcClass Value() const { return impl_->Value(); }
  
    template <class Arc>
    friend void InitMutableArcIteratorClass(
        InitMutableArcIteratorClassArgs *args);
  
   private:
    std::unique_ptr<MutableArcIteratorImplBase> impl_;
  };
  
  template <class Arc>
  void InitMutableArcIteratorClass(InitMutableArcIteratorClassArgs *args) {
    MutableFst<Arc> *fst = std::get<0>(*args)->GetMutableFst<Arc>();
    std::get<2>(*args)->impl_.reset(
        new MutableArcIteratorClassImpl<Arc>(fst, std::get<1>(*args)));
  }
  
  }  // namespace script
  }  // namespace fst
  
  #endif  // FST_SCRIPT_ARCITERATOR_CLASS_H_