Class InlineValue

tensorflow/core/framework/variant.h:402–492

  using HeapValue = std::unique_ptr<ValueInterface>;

  struct InlineValue {
    // We try to size InlineValue so that sizeof(Variant) <= 64 and it can fit
    // into the aligned space of a TensorBuffer.
    static constexpr int kMaxValueSize = (64 - /*some extra padding=*/16);

    typedef char ValueDataArray[kMaxValueSize];
    alignas(kMaxInlineValueAlignSize) ValueDataArray value_data;
    bool has_value = false;

    explicit InlineValue() {}

    InlineValue(const InlineValue& other) noexcept
        : has_value(other.has_value) {
      if (other.has_value) {
        other.AsValueInterface()->CloneInto(AsValueInterface());
      }
    }

    InlineValue(InlineValue&& other) noexcept : has_value(other.has_value) {
      if (other.has_value) {
        other.AsValueInterface()->MoveInto(AsValueInterface());
        other.Cleanup();
      }
    }

    void Cleanup() {
      // **NOTE** This must be a no-op if the memory representation of
      // InlineValue is all zeros, in order to properly interact with
      // HeapOrInline::ResetMemory().
      if (has_value) {
        // This doesn't actually delete anything on the heap; the delete
        // operator of Value<VT> is overridden to do nothing for inline
        // values; the side-effect of delete is that the virtual destructor is
        // called.
        //
        // We leave it to callers to overwrite the data buffer in value_data
        // with new objects.
        delete AsValueInterface();
      }
      has_value = false;
    }

    InlineValue& operator=(const InlineValue& other) {
      if (&other == this) return *this;
      Cleanup();
      if (other.has_value) {
        other.AsValueInterface()->CloneInto(AsValueInterface());
      }
      has_value = other.has_value;
      return *this;
    }

    InlineValue& operator=(InlineValue&& other) {
      if (&other == this) return *this;
      if (other.has_value) {
        if (has_value && AsValueInterface()->TypeId() ==
                             other.AsValueInterface()->TypeId()) {
          other.AsValueInterface()->Swap(AsValueInterface());