Class Value

tensorflow/core/framework/variant.h:305–397

  template <typename T>
  struct Value : ValueInterface {
    template <class... Args>
    explicit Value(in_place_t /*tag*/, Args&&... args)
        : value(std::forward<Args>(args)...) {}

    // NOTE(ebrevdo): Destructor must be explicitly defined for CUDA to happily
    // build `alignof(Variant<void*>)`.
    ~Value() final = default;

    TypeIndex TypeId() const override {
      const TypeIndex value_type_index =
          MakeTypeIndex<typename std::decay<T>::type>();
      return value_type_index;
    }

    void* RawPtr() override { return &value; }

    const void* RawPtr() const override { return &value; }

    ValueInterface* Clone() const override {
      // NOTE: Use placement new here because we override `operator delete`,
      // and need to match the call to `port::Free()` with a call to
      // `port::Malloc()`.
      auto* clone = static_cast<Value*>(port::Malloc(sizeof(Value)));
      new (clone) Value(kInPlace, value);
      return clone;
    }

    void MoveAssign(ValueInterface* memory) override {
      CHECK(TypeId() == memory->TypeId())
          << TypeId().name() << " vs. " << memory->TypeId().name();
      static_cast<Value*>(memory)->value = std::move(value);
    }

    void CloneInto(ValueInterface* memory) const override {
      new (memory) Value(kInPlace, value);
    }

    void MoveInto(ValueInterface* memory) override {
      new (memory) Value(kInPlace, std::move(value));
    }

    void Swap(ValueInterface* memory) override {
      CHECK(TypeId() == memory->TypeId())
          << TypeId().name() << " vs. " << memory->TypeId().name();
      std::swap(value, static_cast<Value*>(memory)->value);
    }

    string TypeName() const override { return TypeNameVariant(value); }

    string DebugString() const override { return DebugStringVariant(value); }

    void Encode(VariantTensorData* data) const override {
      EncodeVariant(value, data);
    }

    bool Decode(VariantTensorData data) override {
      return DecodeVariant(&data, &value);