githubmirror/node

src/aliased_struct.h
63 строки1 KB
James M Snell
src: add AliasedStruct utility
14 апр 2020, 03:21
14 апр 2020, 03:21cecb08f
#ifndef SRC_ALIASED_STRUCT_H_
#define SRC_ALIASED_STRUCT_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "node_internals.h"
#include "v8.h"
#include <memory>

namespace node {

// AliasedStruct is a utility that allows uses a V8 Backing Store
// to be exposed to the C++/C side as a struct and to the
// JavaScript side as an ArrayBuffer to efficiently share
// data without marshalling. It is similar in nature to
// AliasedBuffer.
//
//   struct Foo { int x; }
//
//   AliasedStruct<Foo> foo;
//   foo->x = 1;
//
//   Local<ArrayBuffer> ab = foo.GetArrayBuffer();
template <typename T>
class AliasedStruct final {
 public:
  template <typename... Args>
  explicit AliasedStruct(v8::Isolate* isolate, Args&&... args);

  inline AliasedStruct(const AliasedStruct& that);

  inline ~AliasedStruct();

  inline AliasedStruct& operator=(AliasedStruct&& that) noexcept;

  v8::Local<v8::ArrayBuffer> GetArrayBuffer() const {
    return buffer_.Get(isolate_);
  }

  const T* Data() const { return ptr_; }

  T* Data() { return ptr_; }

  const T& operator*() const { return *ptr_; }

  T& operator*()  { return *ptr_; }

  const T* operator->() const { return ptr_; }

  T* operator->() { return ptr_; }

 private:
  v8::Isolate* isolate_;
  std::shared_ptr<v8::BackingStore> store_;
  T* ptr_;
  v8::Global<v8::ArrayBuffer> buffer_;
};

}  // namespace node

#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif  // SRC_ALIASED_STRUCT_H_