third_party/WebKit/Source/bindings/core/v8/ScopedPersistent.h

/*
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#ifndef ScopedPersistent_h
#define ScopedPersistent_h

#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"
#include <memory>
#include <v8.h>

namespace blink {

template <typename T>
class ScopedPersistent {
  USING_FAST_MALLOC(ScopedPersistent);
  WTF_MAKE_NONCOPYABLE(ScopedPersistent);

 public:
  ScopedPersistent() {}

  ScopedPersistent(v8::Isolate* isolate, v8::Local<T> handle)
      : m_handle(isolate, handle) {}

  ScopedPersistent(v8::Isolate* isolate, v8::MaybeLocal<T> maybe) {
    v8::Local<T> local;
    if (maybe.ToLocal(&local))
      m_handle.Reset(isolate, local);
  }

  ~ScopedPersistent() { clear(); }

  ALWAYS_INLINE v8::Local<T> newLocal(v8::Isolate* isolate) const {
    return v8::Local<T>::New(isolate, m_handle);
  }

  // If you don't need to get weak callback, use setPhantom instead.
  // setPhantom is faster than setWeak.
  template <typename P>
  void setWeak(P* parameters,
               void (*callback)(const v8::WeakCallbackInfo<P>&),
               v8::WeakCallbackType type = v8::WeakCallbackType::kParameter) {
    m_handle.SetWeak(parameters, callback, type);
  }

  // Turns this handle into a weak phantom handle without
  // finalization callback.
  void setPhantom() { m_handle.SetWeak(); }

  void clearWeak() { m_handle.template ClearWeak<void>(); }

  bool isEmpty() const { return m_handle.IsEmpty(); }
  bool isWeak() const { return m_handle.IsWeak(); }

  void set(v8::Isolate* isolate, v8::Local<T> handle) {
    m_handle.Reset(isolate, handle);
  }

  // Note: This is clear in the std::unique_ptr sense, not the v8::Handle sense.
  void clear() { m_handle.Reset(); }

  void setReference(const v8::Persistent<v8::Object>& parent,
                    v8::Isolate* isolate) {
    isolate->SetReference(parent, m_handle);
  }

  bool operator==(const ScopedPersistent<T>& other) {
    return m_handle == other.m_handle;
  }

  template <class S>
  bool operator==(const v8::Local<S> other) const {
    return m_handle == other;
  }

  ALWAYS_INLINE v8::Persistent<T>& get() { return m_handle; }

 private:
  v8::Persistent<T> m_handle;
};

}  // namespace blink

#endif  // ScopedPersistent_h