v8-weak-callback-info.h

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// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef INCLUDE_V8_WEAK_CALLBACK_INFO_H_
#define INCLUDE_V8_WEAK_CALLBACK_INFO_H_
 
#include <cstring>
 
#include "cppgc/internal/conditional-stack-allocated.h"  // NOLINT(build/include_directory)
#include "v8config.h"  // NOLINT(build/include_directory)
 
namespace v8 {
 
class Isolate;
 
namespace api_internal {
V8_EXPORT void InternalFieldOutOfBounds(int index);
}  // namespace api_internal
 
static constexpr int kInternalFieldsInWeakCallback = 2;
static constexpr int kEmbedderFieldsInWeakCallback = 2;
 
template <typename T>
class WeakCallbackInfo
    : public cppgc::internal::ConditionalStackAllocatedBase<T> {
 public:
  using Callback = void (*)(const WeakCallbackInfo<T>& data);
 
  WeakCallbackInfo(Isolate* isolate, T* parameter,
                   void* embedder_fields[kEmbedderFieldsInWeakCallback],
                   Callback* callback)
      : isolate_(isolate), parameter_(parameter), callback_(callback) {
    memcpy(embedder_fields_, embedder_fields,
           sizeof(embedder_fields[0]) * kEmbedderFieldsInWeakCallback);
  }
 
  V8_INLINE Isolate* GetIsolate() const { return isolate_; }
  V8_INLINE T* GetParameter() const { return parameter_; }
  V8_INLINE void* GetInternalField(int index) const;

  void SetSecondPassCallback(Callback callback) const { *callback_ = callback; }
 
 private:
  Isolate* isolate_;
  T* parameter_;
  Callback* callback_;
  void* embedder_fields_[kEmbedderFieldsInWeakCallback];
};

enum class WeakCallbackType {
  kParameter,
  kInternalFields,
};
 
template <class T>
void* WeakCallbackInfo<T>::GetInternalField(int index) const {
#ifdef V8_ENABLE_CHECKS
  if (index < 0 || index >= kEmbedderFieldsInWeakCallback) {
    api_internal::InternalFieldOutOfBounds(index);
  }
#endif
  return embedder_fields_[index];
}
 
}  // namespace v8
 
#endif  // INCLUDE_V8_WEAK_CALLBACK_INFO_H_