v8.h

Go to the documentation of this file.

// Copyright 2012 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_H_
#define INCLUDE_V8_H_
 
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
 
#include <memory>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>
 
#include "cppgc/common.h"
#include "v8-internal.h"  // NOLINT(build/include_directory)
#include "v8-version.h"   // NOLINT(build/include_directory)
#include "v8config.h"     // NOLINT(build/include_directory)
 
// We reserve the V8_* prefix for macros defined in V8 public API and
// assume there are no name conflicts with the embedder's code.
 
namespace v8 {
 
class AccessorSignature;
class Array;
class ArrayBuffer;
class BigInt;
class BigIntObject;
class Boolean;
class BooleanObject;
class Context;
class Data;
class Date;
class External;
class Function;
class FunctionTemplate;
class HeapProfiler;
class ImplementationUtilities;
class Int32;
class Integer;
class Isolate;
template <class T>
class Maybe;
class MicrotaskQueue;
class Name;
class Number;
class NumberObject;
class Object;
class ObjectOperationDescriptor;
class ObjectTemplate;
class Platform;
class Primitive;
class Promise;
class PropertyDescriptor;
class Proxy;
class RawOperationDescriptor;
class Script;
class SharedArrayBuffer;
class Signature;
class StartupData;
class StackFrame;
class StackTrace;
class String;
class StringObject;
class Symbol;
class SymbolObject;
class PrimitiveArray;
class Private;
class Uint32;
class Utils;
class Value;
class WasmModuleObject;
template <class T> class Local;
template <class T>
class MaybeLocal;
template <class T> class Eternal;
template<class T> class NonCopyablePersistentTraits;
template<class T> class PersistentBase;
template <class T, class M = NonCopyablePersistentTraits<T> >
class Persistent;
template <class T>
class Global;
template <class T>
class TracedGlobal;
template <class T>
class TracedReference;
template <class T>
class TracedReferenceBase;
template<class K, class V, class T> class PersistentValueMap;
template <class K, class V, class T>
class PersistentValueMapBase;
template <class K, class V, class T>
class GlobalValueMap;
template<class V, class T> class PersistentValueVector;
template<class T, class P> class WeakCallbackObject;
class FunctionTemplate;
class ObjectTemplate;
template<typename T> class FunctionCallbackInfo;
template<typename T> class PropertyCallbackInfo;
class StackTrace;
class StackFrame;
class Isolate;
class CallHandlerHelper;
class EscapableHandleScope;
template<typename T> class ReturnValue;
 
namespace internal {
enum class ArgumentsType;
template <ArgumentsType>
class Arguments;
template <typename T>
class CustomArguments;
class DeferredHandles;
class FunctionCallbackArguments;
class GlobalHandles;
class Heap;
class HeapObject;
class ExternalString;
class Isolate;
class LocalEmbedderHeapTracer;
class MicrotaskQueue;
class PropertyCallbackArguments;
class ReadOnlyHeap;
class ScopedExternalStringLock;
struct ScriptStreamingData;
class ThreadLocalTop;
 
namespace wasm {
class NativeModule;
class StreamingDecoder;
}  // namespace wasm
 
}  // namespace internal
 
namespace debug {
class ConsoleCallArguments;
}  // namespace debug
 
// --- Handles ---
 
template <class T>
class Local {
 public:
  V8_INLINE Local() : val_(nullptr) {}
  template <class S>
  V8_INLINE Local(Local<S> that)
      : val_(reinterpret_cast<T*>(*that)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
 
  V8_INLINE void Clear() { val_ = nullptr; }
 
  V8_INLINE T* operator->() const { return val_; }
 
  V8_INLINE T* operator*() const { return val_; }
 
  template <class S>
  V8_INLINE bool operator==(const Local<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S> V8_INLINE bool operator==(
      const PersistentBase<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S>
  V8_INLINE bool operator!=(const Local<S>& that) const {
    return !operator==(that);
  }
 
  template <class S> V8_INLINE bool operator!=(
      const Persistent<S>& that) const {
    return !operator==(that);
  }
 
  template <class S> V8_INLINE static Local<T> Cast(Local<S> that) {
#ifdef V8_ENABLE_CHECKS
    // If we're going to perform the type check then we have to check
    // that the handle isn't empty before doing the checked cast.
    if (that.IsEmpty()) return Local<T>();
#endif
    return Local<T>(T::Cast(*that));
  }
 
  template <class S>
  V8_INLINE Local<S> As() const {
    return Local<S>::Cast(*this);
  }
 
  V8_INLINE static Local<T> New(Isolate* isolate, Local<T> that);
  V8_INLINE static Local<T> New(Isolate* isolate,
                                const PersistentBase<T>& that);
  V8_INLINE static Local<T> New(Isolate* isolate,
                                const TracedReferenceBase<T>& that);
 
 private:
  friend class Utils;
  template<class F> friend class Eternal;
  template<class F> friend class PersistentBase;
  template<class F, class M> friend class Persistent;
  template<class F> friend class Local;
  template <class F>
  friend class MaybeLocal;
  template<class F> friend class FunctionCallbackInfo;
  template<class F> friend class PropertyCallbackInfo;
  friend class String;
  friend class Object;
  friend class Context;
  friend class Isolate;
  friend class Private;
  template<class F> friend class internal::CustomArguments;
  friend Local<Primitive> Undefined(Isolate* isolate);
  friend Local<Primitive> Null(Isolate* isolate);
  friend Local<Boolean> True(Isolate* isolate);
  friend Local<Boolean> False(Isolate* isolate);
  friend class HandleScope;
  friend class EscapableHandleScope;
  template <class F1, class F2, class F3>
  friend class PersistentValueMapBase;
  template<class F1, class F2> friend class PersistentValueVector;
  template <class F>
  friend class ReturnValue;
  template <class F>
  friend class Traced;
  template <class F>
  friend class TracedGlobal;
  template <class F>
  friend class TracedReferenceBase;
  template <class F>
  friend class TracedReference;
 
  explicit V8_INLINE Local(T* that) : val_(that) {}
  V8_INLINE static Local<T> New(Isolate* isolate, T* that);
  T* val_;
};
 
 
#if !defined(V8_IMMINENT_DEPRECATION_WARNINGS)
// Handle is an alias for Local for historical reasons.
template <class T>
using Handle = Local<T>;
#endif
 
 
template <class T>
class MaybeLocal {
 public:
  V8_INLINE MaybeLocal() : val_(nullptr) {}
  template <class S>
  V8_INLINE MaybeLocal(Local<S> that)
      : val_(reinterpret_cast<T*>(*that)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
 
  template <class S>
  V8_WARN_UNUSED_RESULT V8_INLINE bool ToLocal(Local<S>* out) const {
    out->val_ = IsEmpty() ? nullptr : this->val_;
    return !IsEmpty();
  }
 
  V8_INLINE Local<T> ToLocalChecked();
 
  template <class S>
  V8_INLINE Local<S> FromMaybe(Local<S> default_value) const {
    return IsEmpty() ? default_value : Local<S>(val_);
  }
 
 private:
  T* val_;
};
 
template <class T> class Eternal {
 public:
  V8_INLINE Eternal() : val_(nullptr) {}
  template <class S>
  V8_INLINE Eternal(Isolate* isolate, Local<S> handle) : val_(nullptr) {
    Set(isolate, handle);
  }
  // Can only be safely called if already set.
  V8_INLINE Local<T> Get(Isolate* isolate) const;
  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
  template<class S> V8_INLINE void Set(Isolate* isolate, Local<S> handle);
 
 private:
  T* val_;
};
 
 
static const int kInternalFieldsInWeakCallback = 2;
static const int kEmbedderFieldsInWeakCallback = 2;
 
template <typename T>
class WeakCallbackInfo {
 public:
  typedef void (*Callback)(const WeakCallbackInfo<T>& data);
 
  WeakCallbackInfo(Isolate* isolate, T* parameter,
                   void* embedder_fields[kEmbedderFieldsInWeakCallback],
                   Callback* callback)
      : isolate_(isolate), parameter_(parameter), callback_(callback) {
    for (int i = 0; i < kEmbedderFieldsInWeakCallback; ++i) {
      embedder_fields_[i] = embedder_fields[i];
    }
  }
 
  V8_INLINE Isolate* GetIsolate() const { return isolate_; }
  V8_INLINE T* GetParameter() const { return parameter_; }
  V8_INLINE void* GetInternalField(int index) const;
 
  // When first called, the embedder MUST Reset() the Global which triggered the
  // callback. The Global itself is unusable for anything else. No v8 other api
  // calls may be called in the first callback. Should additional work be
  // required, the embedder must set a second pass callback, which will be
  // called after all the initial callbacks are processed.
  // Calling SetSecondPassCallback on the second pass will immediately crash.
  void SetSecondPassCallback(Callback callback) const { *callback_ = callback; }
 
 private:
  Isolate* isolate_;
  T* parameter_;
  Callback* callback_;
  void* embedder_fields_[kEmbedderFieldsInWeakCallback];
};
 
 
// kParameter will pass a void* parameter back to the callback, kInternalFields
// will pass the first two internal fields back to the callback, kFinalizer
// will pass a void* parameter back, but is invoked before the object is
// actually collected, so it can be resurrected. In the last case, it is not
// possible to request a second pass callback.
enum class WeakCallbackType { kParameter, kInternalFields, kFinalizer };
 
template <class T> class PersistentBase {
 public:
  V8_INLINE void Reset();
  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const Local<S>& other);
 
  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const PersistentBase<S>& other);
 
  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
  V8_INLINE void Empty() { val_ = 0; }
 
  V8_INLINE Local<T> Get(Isolate* isolate) const {
    return Local<T>::New(isolate, *this);
  }
 
  template <class S>
  V8_INLINE bool operator==(const PersistentBase<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S>
  V8_INLINE bool operator==(const Local<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S>
  V8_INLINE bool operator!=(const PersistentBase<S>& that) const {
    return !operator==(that);
  }
 
  template <class S>
  V8_INLINE bool operator!=(const Local<S>& that) const {
    return !operator==(that);
  }
 
  template <typename P>
  V8_INLINE void SetWeak(P* parameter,
                         typename WeakCallbackInfo<P>::Callback callback,
                         WeakCallbackType type);
 
  V8_INLINE void SetWeak();
 
  template<typename P>
  V8_INLINE P* ClearWeak();
 
  // TODO(dcarney): remove this.
  V8_INLINE void ClearWeak() { ClearWeak<void>(); }
 
  V8_INLINE void AnnotateStrongRetainer(const char* label);
 
  V8_INLINE bool IsWeak() const;
 
  V8_INLINE void SetWrapperClassId(uint16_t class_id);
 
  V8_INLINE uint16_t WrapperClassId() const;
 
  PersistentBase(const PersistentBase& other) = delete;  // NOLINT
  void operator=(const PersistentBase&) = delete;
 
 private:
  friend class Isolate;
  friend class Utils;
  template<class F> friend class Local;
  template<class F1, class F2> friend class Persistent;
  template <class F>
  friend class Global;
  template<class F> friend class PersistentBase;
  template<class F> friend class ReturnValue;
  template <class F1, class F2, class F3>
  friend class PersistentValueMapBase;
  template<class F1, class F2> friend class PersistentValueVector;
  friend class Object;
 
  explicit V8_INLINE PersistentBase(T* val) : val_(val) {}
  V8_INLINE static T* New(Isolate* isolate, T* that);
 
  T* val_;
};
 
 
template<class T>
class NonCopyablePersistentTraits {
 public:
  typedef Persistent<T, NonCopyablePersistentTraits<T> > NonCopyablePersistent;
  static const bool kResetInDestructor = false;
  template<class S, class M>
  V8_INLINE static void Copy(const Persistent<S, M>& source,
                             NonCopyablePersistent* dest) {
    static_assert(sizeof(S) < 0,
                  "NonCopyablePersistentTraits::Copy is not instantiable");
  }
};
 
 
template<class T>
struct CopyablePersistentTraits {
  typedef Persistent<T, CopyablePersistentTraits<T> > CopyablePersistent;
  static const bool kResetInDestructor = true;
  template<class S, class M>
  static V8_INLINE void Copy(const Persistent<S, M>& source,
                             CopyablePersistent* dest) {
    // do nothing, just allow copy
  }
};
 
 
template <class T, class M> class Persistent : public PersistentBase<T> {
 public:
  V8_INLINE Persistent() : PersistentBase<T>(nullptr) {}
  template <class S>
  V8_INLINE Persistent(Isolate* isolate, Local<S> that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
  template <class S, class M2>
  V8_INLINE Persistent(Isolate* isolate, const Persistent<S, M2>& that)
    : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
  V8_INLINE Persistent(const Persistent& that) : PersistentBase<T>(nullptr) {
    Copy(that);
  }
  template <class S, class M2>
  V8_INLINE Persistent(const Persistent<S, M2>& that) : PersistentBase<T>(0) {
    Copy(that);
  }
  V8_INLINE Persistent& operator=(const Persistent& that) {
    Copy(that);
    return *this;
  }
  template <class S, class M2>
  V8_INLINE Persistent& operator=(const Persistent<S, M2>& that) { // NOLINT
    Copy(that);
    return *this;
  }
  V8_INLINE ~Persistent() {
    if (M::kResetInDestructor) this->Reset();
  }
 
  // TODO(dcarney): this is pretty useless, fix or remove
  template <class S>
  V8_INLINE static Persistent<T>& Cast(const Persistent<S>& that) {  // NOLINT
#ifdef V8_ENABLE_CHECKS
    // If we're going to perform the type check then we have to check
    // that the handle isn't empty before doing the checked cast.
    if (!that.IsEmpty()) T::Cast(*that);
#endif
    return reinterpret_cast<Persistent<T>&>(const_cast<Persistent<S>&>(that));
  }
 
  // TODO(dcarney): this is pretty useless, fix or remove
  template <class S>
  V8_INLINE Persistent<S>& As() const {  // NOLINT
    return Persistent<S>::Cast(*this);
  }
 
 private:
  friend class Isolate;
  friend class Utils;
  template<class F> friend class Local;
  template<class F1, class F2> friend class Persistent;
  template<class F> friend class ReturnValue;
 
  explicit V8_INLINE Persistent(T* that) : PersistentBase<T>(that) {}
  V8_INLINE T* operator*() const { return this->val_; }
  template<class S, class M2>
  V8_INLINE void Copy(const Persistent<S, M2>& that);
};
 
 
template <class T>
class Global : public PersistentBase<T> {
 public:
  V8_INLINE Global() : PersistentBase<T>(nullptr) {}
 
  template <class S>
  V8_INLINE Global(Isolate* isolate, Local<S> that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  template <class S>
  V8_INLINE Global(Isolate* isolate, const PersistentBase<S>& that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, that.val_)) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  V8_INLINE Global(Global&& other);
 
  V8_INLINE ~Global() { this->Reset(); }
 
  template <class S>
  V8_INLINE Global& operator=(Global<S>&& rhs);
 
  Global Pass() { return static_cast<Global&&>(*this); }  // NOLINT
 
  /*
   * For compatibility with Chromium's base::Bind (base::Passed).
   */
  typedef void MoveOnlyTypeForCPP03;
 
  Global(const Global&) = delete;
  void operator=(const Global&) = delete;
 
 private:
  template <class F>
  friend class ReturnValue;
  V8_INLINE T* operator*() const { return this->val_; }
};
 
 
// UniquePersistent is an alias for Global for historical reason.
template <class T>
using UniquePersistent = Global<T>;
 
template <typename T>
struct TracedGlobalTrait {};
 
template <typename T>
class TracedReferenceBase {
 public:
  bool IsEmpty() const { return val_ == nullptr; }
 
  V8_INLINE void Reset();
 
  Local<T> Get(Isolate* isolate) const { return Local<T>::New(isolate, *this); }
 
  template <class S>
  V8_INLINE bool operator==(const TracedReferenceBase<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S>
  V8_INLINE bool operator==(const Local<S>& that) const {
    internal::Address* a = reinterpret_cast<internal::Address*>(val_);
    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
    if (a == nullptr) return b == nullptr;
    if (b == nullptr) return false;
    return *a == *b;
  }
 
  template <class S>
  V8_INLINE bool operator!=(const TracedReferenceBase<S>& that) const {
    return !operator==(that);
  }
 
  template <class S>
  V8_INLINE bool operator!=(const Local<S>& that) const {
    return !operator==(that);
  }
 
  V8_INLINE void SetWrapperClassId(uint16_t class_id);
 
  V8_INLINE uint16_t WrapperClassId() const;
 
  template <class S>
  V8_INLINE TracedReferenceBase<S>& As() const {
    return reinterpret_cast<TracedReferenceBase<S>&>(
        const_cast<TracedReferenceBase<T>&>(*this));
  }
 
 private:
  enum DestructionMode { kWithDestructor, kWithoutDestructor };
 
  TracedReferenceBase() = default;
 
  V8_INLINE static T* New(Isolate* isolate, T* that, void* slot,
                          DestructionMode destruction_mode);
 
  T* val_ = nullptr;
 
  friend class EmbedderHeapTracer;
  template <typename F>
  friend class Local;
  friend class Object;
  template <typename F>
  friend class TracedGlobal;
  template <typename F>
  friend class TracedReference;
  template <typename F>
  friend class ReturnValue;
};
 
template <typename T>
class TracedGlobal : public TracedReferenceBase<T> {
 public:
  using TracedReferenceBase<T>::Reset;
 
  ~TracedGlobal() { this->Reset(); }
 
  TracedGlobal() : TracedReferenceBase<T>() {}
 
  template <class S>
  TracedGlobal(Isolate* isolate, Local<S> that) : TracedReferenceBase<T>() {
    this->val_ = this->New(isolate, that.val_, &this->val_,
                           TracedReferenceBase<T>::kWithDestructor);
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  V8_INLINE TracedGlobal(TracedGlobal&& other) {
    // Forward to operator=.
    *this = std::move(other);
  }
 
  template <typename S>
  V8_INLINE TracedGlobal(TracedGlobal<S>&& other) {
    // Forward to operator=.
    *this = std::move(other);
  }
 
  V8_INLINE TracedGlobal(const TracedGlobal& other) {
    // Forward to operator=;
    *this = other;
  }
 
  template <typename S>
  V8_INLINE TracedGlobal(const TracedGlobal<S>& other) {
    // Forward to operator=;
    *this = other;
  }
 
  V8_INLINE TracedGlobal& operator=(TracedGlobal&& rhs);
 
  template <class S>
  V8_INLINE TracedGlobal& operator=(TracedGlobal<S>&& rhs);
 
  V8_INLINE TracedGlobal& operator=(const TracedGlobal& rhs);
 
  template <class S>
  V8_INLINE TracedGlobal& operator=(const TracedGlobal<S>& rhs);
 
  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const Local<S>& other);
 
  template <class S>
  V8_INLINE TracedGlobal<S>& As() const {
    return reinterpret_cast<TracedGlobal<S>&>(
        const_cast<TracedGlobal<T>&>(*this));
  }
 
  V8_INLINE void SetFinalizationCallback(
      void* parameter, WeakCallbackInfo<void>::Callback callback);
};
 
template <typename T>
class TracedReference : public TracedReferenceBase<T> {
 public:
  using TracedReferenceBase<T>::Reset;
 
  TracedReference() : TracedReferenceBase<T>() {}
 
  template <class S>
  TracedReference(Isolate* isolate, Local<S> that) : TracedReferenceBase<T>() {
    this->val_ = this->New(isolate, that.val_, &this->val_,
                           TracedReferenceBase<T>::kWithoutDestructor);
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
 
  V8_INLINE TracedReference(TracedReference&& other) {
    // Forward to operator=.
    *this = std::move(other);
  }
 
  template <typename S>
  V8_INLINE TracedReference(TracedReference<S>&& other) {
    // Forward to operator=.
    *this = std::move(other);
  }
 
  V8_INLINE TracedReference(const TracedReference& other) {
    // Forward to operator=;
    *this = other;
  }
 
  template <typename S>
  V8_INLINE TracedReference(const TracedReference<S>& other) {
    // Forward to operator=;
    *this = other;
  }
 
  V8_INLINE TracedReference& operator=(TracedReference&& rhs);
 
  template <class S>
  V8_INLINE TracedReference& operator=(TracedReference<S>&& rhs);
 
  V8_INLINE TracedReference& operator=(const TracedReference& rhs);
 
  template <class S>
  V8_INLINE TracedReference& operator=(const TracedReference<S>& rhs);
 
  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const Local<S>& other);
 
  template <class S>
  V8_INLINE TracedReference<S>& As() const {
    return reinterpret_cast<TracedReference<S>&>(
        const_cast<TracedReference<T>&>(*this));
  }
};
 
class V8_EXPORT HandleScope {
 public:
  explicit HandleScope(Isolate* isolate);
 
  ~HandleScope();
 
  static int NumberOfHandles(Isolate* isolate);
 
  V8_INLINE Isolate* GetIsolate() const {
    return reinterpret_cast<Isolate*>(isolate_);
  }
 
  HandleScope(const HandleScope&) = delete;
  void operator=(const HandleScope&) = delete;
 
 protected:
  V8_INLINE HandleScope() = default;
 
  void Initialize(Isolate* isolate);
 
  static internal::Address* CreateHandle(internal::Isolate* isolate,
                                         internal::Address value);
 
 private:
  // Declaring operator new and delete as deleted is not spec compliant.
  // Therefore declare them private instead to disable dynamic alloc
  void* operator new(size_t size);
  void* operator new[](size_t size);
  void operator delete(void*, size_t);
  void operator delete[](void*, size_t);
 
  internal::Isolate* isolate_;
  internal::Address* prev_next_;
  internal::Address* prev_limit_;
 
  // Local::New uses CreateHandle with an Isolate* parameter.
  template<class F> friend class Local;
 
  // Object::GetInternalField and Context::GetEmbedderData use CreateHandle with
  // a HeapObject in their shortcuts.
  friend class Object;
  friend class Context;
};
 
 
class V8_EXPORT EscapableHandleScope : public HandleScope {
 public:
  explicit EscapableHandleScope(Isolate* isolate);
  V8_INLINE ~EscapableHandleScope() = default;
 
  template <class T>
  V8_INLINE Local<T> Escape(Local<T> value) {
    internal::Address* slot =
        Escape(reinterpret_cast<internal::Address*>(*value));
    return Local<T>(reinterpret_cast<T*>(slot));
  }
 
  template <class T>
  V8_INLINE MaybeLocal<T> EscapeMaybe(MaybeLocal<T> value) {
    return Escape(value.FromMaybe(Local<T>()));
  }
 
  EscapableHandleScope(const EscapableHandleScope&) = delete;
  void operator=(const EscapableHandleScope&) = delete;
 
 private:
  // Declaring operator new and delete as deleted is not spec compliant.
  // Therefore declare them private instead to disable dynamic alloc
  void* operator new(size_t size);
  void* operator new[](size_t size);
  void operator delete(void*, size_t);
  void operator delete[](void*, size_t);
 
  internal::Address* Escape(internal::Address* escape_value);
  internal::Address* escape_slot_;
};
 
class V8_EXPORT SealHandleScope {
 public:
  explicit SealHandleScope(Isolate* isolate);
  ~SealHandleScope();
 
  SealHandleScope(const SealHandleScope&) = delete;
  void operator=(const SealHandleScope&) = delete;
 
 private:
  // Declaring operator new and delete as deleted is not spec compliant.
  // Therefore declare them private instead to disable dynamic alloc
  void* operator new(size_t size);
  void* operator new[](size_t size);
  void operator delete(void*, size_t);
  void operator delete[](void*, size_t);
 
  internal::Isolate* const isolate_;
  internal::Address* prev_limit_;
  int prev_sealed_level_;
};
 
 
// --- Special objects ---
 
class V8_EXPORT Data {
 private:
  Data();
};
 
class V8_EXPORT ScriptOrModule {
 public:
  Local<Value> GetResourceName();
 
  Local<PrimitiveArray> GetHostDefinedOptions();
};
 
class V8_EXPORT PrimitiveArray {
 public:
  static Local<PrimitiveArray> New(Isolate* isolate, int length);
  int Length() const;
  void Set(Isolate* isolate, int index, Local<Primitive> item);
  Local<Primitive> Get(Isolate* isolate, int index);
};
 
class ScriptOriginOptions {
 public:
  V8_INLINE ScriptOriginOptions(bool is_shared_cross_origin = false,
                                bool is_opaque = false, bool is_wasm = false,
                                bool is_module = false)
      : flags_((is_shared_cross_origin ? kIsSharedCrossOrigin : 0) |
               (is_wasm ? kIsWasm : 0) | (is_opaque ? kIsOpaque : 0) |
               (is_module ? kIsModule : 0)) {}
  V8_INLINE ScriptOriginOptions(int flags)
      : flags_(flags &
               (kIsSharedCrossOrigin | kIsOpaque | kIsWasm | kIsModule)) {}
 
  bool IsSharedCrossOrigin() const {
    return (flags_ & kIsSharedCrossOrigin) != 0;
  }
  bool IsOpaque() const { return (flags_ & kIsOpaque) != 0; }
  bool IsWasm() const { return (flags_ & kIsWasm) != 0; }
  bool IsModule() const { return (flags_ & kIsModule) != 0; }
 
  int Flags() const { return flags_; }
 
 private:
  enum {
    kIsSharedCrossOrigin = 1,
    kIsOpaque = 1 << 1,
    kIsWasm = 1 << 2,
    kIsModule = 1 << 3
  };
  const int flags_;
};
 
class ScriptOrigin {
 public:
  V8_INLINE ScriptOrigin(
      Local<Value> resource_name,
      Local<Integer> resource_line_offset = Local<Integer>(),
      Local<Integer> resource_column_offset = Local<Integer>(),
      Local<Boolean> resource_is_shared_cross_origin = Local<Boolean>(),
      Local<Integer> script_id = Local<Integer>(),
      Local<Value> source_map_url = Local<Value>(),
      Local<Boolean> resource_is_opaque = Local<Boolean>(),
      Local<Boolean> is_wasm = Local<Boolean>(),
      Local<Boolean> is_module = Local<Boolean>(),
      Local<PrimitiveArray> host_defined_options = Local<PrimitiveArray>());
 
  V8_INLINE Local<Value> ResourceName() const;
  V8_INLINE Local<Integer> ResourceLineOffset() const;
  V8_INLINE Local<Integer> ResourceColumnOffset() const;
  V8_INLINE Local<Integer> ScriptID() const;
  V8_INLINE Local<Value> SourceMapUrl() const;
  V8_INLINE Local<PrimitiveArray> HostDefinedOptions() const;
  V8_INLINE ScriptOriginOptions Options() const { return options_; }
 
 private:
  Local<Value> resource_name_;
  Local<Integer> resource_line_offset_;
  Local<Integer> resource_column_offset_;
  ScriptOriginOptions options_;
  Local<Integer> script_id_;
  Local<Value> source_map_url_;
  Local<PrimitiveArray> host_defined_options_;
};
 
class V8_EXPORT UnboundScript {
 public:
  Local<Script> BindToCurrentContext();
 
  int GetId();
  Local<Value> GetScriptName();
 
  Local<Value> GetSourceURL();
  Local<Value> GetSourceMappingURL();
 
  int GetLineNumber(int code_pos);
 
  static const int kNoScriptId = 0;
};
 
class V8_EXPORT UnboundModuleScript : public Data {
  // Only used as a container for code caching.
};
 
class V8_EXPORT Location {
 public:
  int GetLineNumber() { return line_number_; }
  int GetColumnNumber() { return column_number_; }
 
  Location(int line_number, int column_number)
      : line_number_(line_number), column_number_(column_number) {}
 
 private:
  int line_number_;
  int column_number_;
};
 
class V8_EXPORT Module : public Data {
 public:
  enum Status {
    kUninstantiated,
    kInstantiating,
    kInstantiated,
    kEvaluating,
    kEvaluated,
    kErrored
  };
 
  Status GetStatus() const;
 
  Local<Value> GetException() const;
 
  int GetModuleRequestsLength() const;
 
  Local<String> GetModuleRequest(int i) const;
 
  Location GetModuleRequestLocation(int i) const;
 
  int GetIdentityHash() const;
 
  typedef MaybeLocal<Module> (*ResolveCallback)(Local<Context> context,
                                                Local<String> specifier,
                                                Local<Module> referrer);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> InstantiateModule(Local<Context> context,
                                                      ResolveCallback callback);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Evaluate(Local<Context> context);
 
  Local<Value> GetModuleNamespace();
 
  Local<UnboundModuleScript> GetUnboundModuleScript();
 
  /*
   * Callback defined in the embedder.  This is responsible for setting
   * the module's exported values with calls to SetSyntheticModuleExport().
   * The callback must return a Value to indicate success (where no
   * exception was thrown) and return an empy MaybeLocal to indicate falure
   * (where an exception was thrown).
   */
  typedef MaybeLocal<Value> (*SyntheticModuleEvaluationSteps)(
      Local<Context> context, Local<Module> module);
 
  static Local<Module> CreateSyntheticModule(
      Isolate* isolate, Local<String> module_name,
      const std::vector<Local<String>>& export_names,
      SyntheticModuleEvaluationSteps evaluation_steps);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> SetSyntheticModuleExport(
      Isolate* isolate, Local<String> export_name, Local<Value> export_value);
  V8_DEPRECATE_SOON(
      "Use the preceding SetSyntheticModuleExport with an Isolate parameter, "
      "instead of the one that follows.  The former will throw a runtime "
      "error if called for an export that doesn't exist (as per spec); "
      "the latter will crash with a failed CHECK().")
  void SetSyntheticModuleExport(Local<String> export_name,
                                Local<Value> export_value);
};
 
class V8_EXPORT Script {
 public:
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, Local<String> source,
      ScriptOrigin* origin = nullptr);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Run(Local<Context> context);
 
  Local<UnboundScript> GetUnboundScript();
};
 
 
class V8_EXPORT ScriptCompiler {
 public:
  struct V8_EXPORT CachedData {
    enum BufferPolicy {
      BufferNotOwned,
      BufferOwned
    };
 
    CachedData()
        : data(nullptr),
          length(0),
          rejected(false),
          buffer_policy(BufferNotOwned) {}
 
    // If buffer_policy is BufferNotOwned, the caller keeps the ownership of
    // data and guarantees that it stays alive until the CachedData object is
    // destroyed. If the policy is BufferOwned, the given data will be deleted
    // (with delete[]) when the CachedData object is destroyed.
    CachedData(const uint8_t* data, int length,
               BufferPolicy buffer_policy = BufferNotOwned);
    ~CachedData();
    // TODO(marja): Async compilation; add constructors which take a callback
    // which will be called when V8 no longer needs the data.
    const uint8_t* data;
    int length;
    bool rejected;
    BufferPolicy buffer_policy;
 
    // Prevent copying.
    CachedData(const CachedData&) = delete;
    CachedData& operator=(const CachedData&) = delete;
  };
 
  class Source {
   public:
    // Source takes ownership of CachedData.
    V8_INLINE Source(Local<String> source_string, const ScriptOrigin& origin,
                     CachedData* cached_data = nullptr);
    V8_INLINE Source(Local<String> source_string,
                     CachedData* cached_data = nullptr);
    V8_INLINE ~Source();
 
    // Ownership of the CachedData or its buffers is *not* transferred to the
    // caller. The CachedData object is alive as long as the Source object is
    // alive.
    V8_INLINE const CachedData* GetCachedData() const;
 
    V8_INLINE const ScriptOriginOptions& GetResourceOptions() const;
 
    // Prevent copying.
    Source(const Source&) = delete;
    Source& operator=(const Source&) = delete;
 
   private:
    friend class ScriptCompiler;
 
    Local<String> source_string;
 
    // Origin information
    Local<Value> resource_name;
    Local<Integer> resource_line_offset;
    Local<Integer> resource_column_offset;
    ScriptOriginOptions resource_options;
    Local<Value> source_map_url;
    Local<PrimitiveArray> host_defined_options;
 
    // Cached data from previous compilation (if a kConsume*Cache flag is
    // set), or hold newly generated cache data (kProduce*Cache flags) are
    // set when calling a compile method.
    CachedData* cached_data;
  };
 
  class V8_EXPORT ExternalSourceStream {
   public:
    virtual ~ExternalSourceStream() = default;
 
    virtual size_t GetMoreData(const uint8_t** src) = 0;
 
    virtual bool SetBookmark();
 
    virtual void ResetToBookmark();
  };
 
  class V8_EXPORT StreamedSource {
   public:
    enum Encoding { ONE_BYTE, TWO_BYTE, UTF8 };
 
    V8_DEPRECATE_SOON(
        "This class takes ownership of source_stream, so use the constructor "
        "taking a unique_ptr to make these semantics clearer")
    StreamedSource(ExternalSourceStream* source_stream, Encoding encoding);
    StreamedSource(std::unique_ptr<ExternalSourceStream> source_stream,
                   Encoding encoding);
    ~StreamedSource();
 
    internal::ScriptStreamingData* impl() const { return impl_.get(); }
 
    // Prevent copying.
    StreamedSource(const StreamedSource&) = delete;
    StreamedSource& operator=(const StreamedSource&) = delete;
 
   private:
    std::unique_ptr<internal::ScriptStreamingData> impl_;
  };
 
  class V8_EXPORT ScriptStreamingTask final {
   public:
    void Run();
 
   private:
    friend class ScriptCompiler;
 
    explicit ScriptStreamingTask(internal::ScriptStreamingData* data)
        : data_(data) {}
 
    internal::ScriptStreamingData* data_;
  };
 
  enum CompileOptions {
    kNoCompileOptions = 0,
    kConsumeCodeCache,
    kEagerCompile
  };
 
  enum NoCacheReason {
    kNoCacheNoReason = 0,
    kNoCacheBecauseCachingDisabled,
    kNoCacheBecauseNoResource,
    kNoCacheBecauseInlineScript,
    kNoCacheBecauseModule,
    kNoCacheBecauseStreamingSource,
    kNoCacheBecauseInspector,
    kNoCacheBecauseScriptTooSmall,
    kNoCacheBecauseCacheTooCold,
    kNoCacheBecauseV8Extension,
    kNoCacheBecauseExtensionModule,
    kNoCacheBecausePacScript,
    kNoCacheBecauseInDocumentWrite,
    kNoCacheBecauseResourceWithNoCacheHandler,
    kNoCacheBecauseDeferredProduceCodeCache
  };
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<UnboundScript> CompileUnboundScript(
      Isolate* isolate, Source* source,
      CompileOptions options = kNoCompileOptions,
      NoCacheReason no_cache_reason = kNoCacheNoReason);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, Source* source,
      CompileOptions options = kNoCompileOptions,
      NoCacheReason no_cache_reason = kNoCacheNoReason);
 
  static ScriptStreamingTask* StartStreamingScript(
      Isolate* isolate, StreamedSource* source,
      CompileOptions options = kNoCompileOptions);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, StreamedSource* source,
      Local<String> full_source_string, const ScriptOrigin& origin);
 
  static uint32_t CachedDataVersionTag();
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<Module> CompileModule(
      Isolate* isolate, Source* source,
      CompileOptions options = kNoCompileOptions,
      NoCacheReason no_cache_reason = kNoCacheNoReason);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<Function> CompileFunctionInContext(
      Local<Context> context, Source* source, size_t arguments_count,
      Local<String> arguments[], size_t context_extension_count,
      Local<Object> context_extensions[],
      CompileOptions options = kNoCompileOptions,
      NoCacheReason no_cache_reason = kNoCacheNoReason,
      Local<ScriptOrModule>* script_or_module_out = nullptr);
 
  static CachedData* CreateCodeCache(Local<UnboundScript> unbound_script);
 
  static CachedData* CreateCodeCache(
      Local<UnboundModuleScript> unbound_module_script);
 
  static CachedData* CreateCodeCacheForFunction(Local<Function> function);
 
 private:
  static V8_WARN_UNUSED_RESULT MaybeLocal<UnboundScript> CompileUnboundInternal(
      Isolate* isolate, Source* source, CompileOptions options,
      NoCacheReason no_cache_reason);
};
 
 
class V8_EXPORT Message {
 public:
  Local<String> Get() const;
 
  Isolate* GetIsolate() const;
 
  V8_WARN_UNUSED_RESULT MaybeLocal<String> GetSourceLine(
      Local<Context> context) const;
 
  ScriptOrigin GetScriptOrigin() const;
 
  Local<Value> GetScriptResourceName() const;
 
  Local<StackTrace> GetStackTrace() const;
 
  V8_WARN_UNUSED_RESULT Maybe<int> GetLineNumber(Local<Context> context) const;
 
  int GetStartPosition() const;
 
  int GetEndPosition() const;
 
  int GetWasmFunctionIndex() const;
 
  int ErrorLevel() const;
 
  int GetStartColumn() const;
  V8_WARN_UNUSED_RESULT Maybe<int> GetStartColumn(Local<Context> context) const;
 
  int GetEndColumn() const;
  V8_WARN_UNUSED_RESULT Maybe<int> GetEndColumn(Local<Context> context) const;
 
  bool IsSharedCrossOrigin() const;
  bool IsOpaque() const;
 
  // TODO(1245381): Print to a string instead of on a FILE.
  static void PrintCurrentStackTrace(Isolate* isolate, FILE* out);
 
  static const int kNoLineNumberInfo = 0;
  static const int kNoColumnInfo = 0;
  static const int kNoScriptIdInfo = 0;
  static const int kNoWasmFunctionIndexInfo = -1;
};
 
 
class V8_EXPORT StackTrace {
 public:
  enum StackTraceOptions {
    kLineNumber = 1,
    kColumnOffset = 1 << 1 | kLineNumber,
    kScriptName = 1 << 2,
    kFunctionName = 1 << 3,
    kIsEval = 1 << 4,
    kIsConstructor = 1 << 5,
    kScriptNameOrSourceURL = 1 << 6,
    kScriptId = 1 << 7,
    kExposeFramesAcrossSecurityOrigins = 1 << 8,
    kOverview = kLineNumber | kColumnOffset | kScriptName | kFunctionName,
    kDetailed = kOverview | kIsEval | kIsConstructor | kScriptNameOrSourceURL
  };
 
  Local<StackFrame> GetFrame(Isolate* isolate, uint32_t index) const;
 
  int GetFrameCount() const;
 
  static Local<StackTrace> CurrentStackTrace(
      Isolate* isolate, int frame_limit, StackTraceOptions options = kDetailed);
};
 
 
class V8_EXPORT StackFrame {
 public:
  int GetLineNumber() const;
 
  int GetColumn() const;
 
  int GetScriptId() const;
 
  Local<String> GetScriptName() const;
 
  Local<String> GetScriptNameOrSourceURL() const;
 
  Local<String> GetFunctionName() const;
 
  bool IsEval() const;
 
  bool IsConstructor() const;
 
  bool IsWasm() const;
 
  bool IsUserJavaScript() const;
};
 
 
// A StateTag represents a possible state of the VM.
enum StateTag {
  JS,
  GC,
  PARSER,
  BYTECODE_COMPILER,
  COMPILER,
  OTHER,
  EXTERNAL,
  ATOMICS_WAIT,
  IDLE
};
 
// A RegisterState represents the current state of registers used
// by the sampling profiler API.
struct RegisterState {
  RegisterState() : pc(nullptr), sp(nullptr), fp(nullptr), lr(nullptr) {}
  void* pc;  // Instruction pointer.
  void* sp;  // Stack pointer.
  void* fp;  // Frame pointer.
  void* lr;  // Link register (or nullptr on platforms without a link register).
};
 
// The output structure filled up by GetStackSample API function.
struct SampleInfo {
  size_t frames_count;            // Number of frames collected.
  StateTag vm_state;              // Current VM state.
  void* external_callback_entry;  // External callback address if VM is
                                  // executing an external callback.
  void* top_context;              // Incumbent native context address.
};
 
struct MemoryRange {
  const void* start = nullptr;
  size_t length_in_bytes = 0;
};
 
struct JSEntryStub {
  MemoryRange code;
};
 
struct UnwindState {
  MemoryRange code_range;
  MemoryRange embedded_code_range;
  JSEntryStub js_entry_stub;
  JSEntryStub js_construct_entry_stub;
  JSEntryStub js_run_microtasks_entry_stub;
};
 
struct JSEntryStubs {
  JSEntryStub js_entry_stub;
  JSEntryStub js_construct_entry_stub;
  JSEntryStub js_run_microtasks_entry_stub;
};
 
class V8_EXPORT JSON {
 public:
  static V8_WARN_UNUSED_RESULT MaybeLocal<Value> Parse(
      Local<Context> context, Local<String> json_string);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> Stringify(
      Local<Context> context, Local<Value> json_object,
      Local<String> gap = Local<String>());
};
 
class V8_EXPORT ValueSerializer {
 public:
  class V8_EXPORT Delegate {
   public:
    virtual ~Delegate() = default;
 
    virtual void ThrowDataCloneError(Local<String> message) = 0;
 
    virtual Maybe<bool> WriteHostObject(Isolate* isolate, Local<Object> object);
 
    virtual Maybe<uint32_t> GetSharedArrayBufferId(
        Isolate* isolate, Local<SharedArrayBuffer> shared_array_buffer);
 
    virtual Maybe<uint32_t> GetWasmModuleTransferId(
        Isolate* isolate, Local<WasmModuleObject> module);
    virtual void* ReallocateBufferMemory(void* old_buffer, size_t size,
                                         size_t* actual_size);
 
    virtual void FreeBufferMemory(void* buffer);
  };
 
  explicit ValueSerializer(Isolate* isolate);
  ValueSerializer(Isolate* isolate, Delegate* delegate);
  ~ValueSerializer();
 
  void WriteHeader();
 
  V8_WARN_UNUSED_RESULT Maybe<bool> WriteValue(Local<Context> context,
                                               Local<Value> value);
 
  V8_WARN_UNUSED_RESULT std::pair<uint8_t*, size_t> Release();
 
  void TransferArrayBuffer(uint32_t transfer_id,
                           Local<ArrayBuffer> array_buffer);
 
 
  void SetTreatArrayBufferViewsAsHostObjects(bool mode);
 
  void WriteUint32(uint32_t value);
  void WriteUint64(uint64_t value);
  void WriteDouble(double value);
  void WriteRawBytes(const void* source, size_t length);
 
  ValueSerializer(const ValueSerializer&) = delete;
  void operator=(const ValueSerializer&) = delete;
 
 private:
  struct PrivateData;
  PrivateData* private_;
};
 
class V8_EXPORT ValueDeserializer {
 public:
  class V8_EXPORT Delegate {
   public:
    virtual ~Delegate() = default;
 
    virtual MaybeLocal<Object> ReadHostObject(Isolate* isolate);
 
    virtual MaybeLocal<WasmModuleObject> GetWasmModuleFromId(
        Isolate* isolate, uint32_t transfer_id);
 
    virtual MaybeLocal<SharedArrayBuffer> GetSharedArrayBufferFromId(
        Isolate* isolate, uint32_t clone_id);
  };
 
  ValueDeserializer(Isolate* isolate, const uint8_t* data, size_t size);
  ValueDeserializer(Isolate* isolate, const uint8_t* data, size_t size,
                    Delegate* delegate);
  ~ValueDeserializer();
 
  V8_WARN_UNUSED_RESULT Maybe<bool> ReadHeader(Local<Context> context);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> ReadValue(Local<Context> context);
 
  void TransferArrayBuffer(uint32_t transfer_id,
                           Local<ArrayBuffer> array_buffer);
 
  void TransferSharedArrayBuffer(uint32_t id,
                                 Local<SharedArrayBuffer> shared_array_buffer);
 
  void SetSupportsLegacyWireFormat(bool supports_legacy_wire_format);
 
  uint32_t GetWireFormatVersion() const;
 
  V8_WARN_UNUSED_RESULT bool ReadUint32(uint32_t* value);
  V8_WARN_UNUSED_RESULT bool ReadUint64(uint64_t* value);
  V8_WARN_UNUSED_RESULT bool ReadDouble(double* value);
  V8_WARN_UNUSED_RESULT bool ReadRawBytes(size_t length, const void** data);
 
  ValueDeserializer(const ValueDeserializer&) = delete;
  void operator=(const ValueDeserializer&) = delete;
 
 private:
  struct PrivateData;
  PrivateData* private_;
};
 
 
// --- Value ---
 
 
class V8_EXPORT Value : public Data {
 public:
  V8_INLINE bool IsUndefined() const;
 
  V8_INLINE bool IsNull() const;
 
  V8_INLINE bool IsNullOrUndefined() const;
 
  bool IsTrue() const;
 
  bool IsFalse() const;
 
  bool IsName() const;
 
  V8_INLINE bool IsString() const;
 
  bool IsSymbol() const;
 
  bool IsFunction() const;
 
  bool IsArray() const;
 
  bool IsObject() const;
 
  bool IsBigInt() const;
 
  bool IsBoolean() const;
 
  bool IsNumber() const;
 
  bool IsExternal() const;
 
  bool IsInt32() const;
 
  bool IsUint32() const;
 
  bool IsDate() const;
 
  bool IsArgumentsObject() const;
 
  bool IsBigIntObject() const;
 
  bool IsBooleanObject() const;
 
  bool IsNumberObject() const;
 
  bool IsStringObject() const;
 
  bool IsSymbolObject() const;
 
  bool IsNativeError() const;
 
  bool IsRegExp() const;
 
  bool IsAsyncFunction() const;
 
  bool IsGeneratorFunction() const;
 
  bool IsGeneratorObject() const;
 
  bool IsPromise() const;
 
  bool IsMap() const;
 
  bool IsSet() const;
 
  bool IsMapIterator() const;
 
  bool IsSetIterator() const;
 
  bool IsWeakMap() const;
 
  bool IsWeakSet() const;
 
  bool IsArrayBuffer() const;
 
  bool IsArrayBufferView() const;
 
  bool IsTypedArray() const;
 
  bool IsUint8Array() const;
 
  bool IsUint8ClampedArray() const;
 
  bool IsInt8Array() const;
 
  bool IsUint16Array() const;
 
  bool IsInt16Array() const;
 
  bool IsUint32Array() const;
 
  bool IsInt32Array() const;
 
  bool IsFloat32Array() const;
 
  bool IsFloat64Array() const;
 
  bool IsBigInt64Array() const;
 
  bool IsBigUint64Array() const;
 
  bool IsDataView() const;
 
  bool IsSharedArrayBuffer() const;
 
  bool IsProxy() const;
 
  bool IsWasmModuleObject() const;
 
  bool IsModuleNamespaceObject() const;
 
  V8_WARN_UNUSED_RESULT MaybeLocal<BigInt> ToBigInt(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Number> ToNumber(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<String> ToString(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<String> ToDetailString(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> ToObject(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Integer> ToInteger(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Uint32> ToUint32(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Int32> ToInt32(Local<Context> context) const;
 
  Local<Boolean> ToBoolean(Isolate* isolate) const;
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Uint32> ToArrayIndex(
      Local<Context> context) const;
 
  bool BooleanValue(Isolate* isolate) const;
 
  V8_WARN_UNUSED_RESULT Maybe<double> NumberValue(Local<Context> context) const;
  V8_WARN_UNUSED_RESULT Maybe<int64_t> IntegerValue(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT Maybe<uint32_t> Uint32Value(
      Local<Context> context) const;
  V8_WARN_UNUSED_RESULT Maybe<int32_t> Int32Value(Local<Context> context) const;
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Equals(Local<Context> context,
                                           Local<Value> that) const;
  bool StrictEquals(Local<Value> that) const;
  bool SameValue(Local<Value> that) const;
 
  template <class T> V8_INLINE static Value* Cast(T* value);
 
  Local<String> TypeOf(Isolate*);
 
  Maybe<bool> InstanceOf(Local<Context> context, Local<Object> object);
 
 private:
  V8_INLINE bool QuickIsUndefined() const;
  V8_INLINE bool QuickIsNull() const;
  V8_INLINE bool QuickIsNullOrUndefined() const;
  V8_INLINE bool QuickIsString() const;
  bool FullIsUndefined() const;
  bool FullIsNull() const;
  bool FullIsString() const;
};
 
 
class V8_EXPORT Primitive : public Value { };
 
 
class V8_EXPORT Boolean : public Primitive {
 public:
  bool Value() const;
  V8_INLINE static Boolean* Cast(v8::Value* obj);
  V8_INLINE static Local<Boolean> New(Isolate* isolate, bool value);
 
 private:
  static void CheckCast(v8::Value* obj);
};
 
 
class V8_EXPORT Name : public Primitive {
 public:
  int GetIdentityHash();
 
  V8_INLINE static Name* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
enum class NewStringType {
  kNormal,
 
  kInternalized
};
 
class V8_EXPORT String : public Name {
 public:
  static constexpr int kMaxLength =
      internal::kApiSystemPointerSize == 4 ? (1 << 28) - 16 : (1 << 29) - 24;
 
  enum Encoding {
    UNKNOWN_ENCODING = 0x1,
    TWO_BYTE_ENCODING = 0x0,
    ONE_BYTE_ENCODING = 0x8
  };
  int Length() const;
 
  int Utf8Length(Isolate* isolate) const;
 
  bool IsOneByte() const;
 
  bool ContainsOnlyOneByte() const;
 
  enum WriteOptions {
    NO_OPTIONS = 0,
    HINT_MANY_WRITES_EXPECTED = 1,
    NO_NULL_TERMINATION = 2,
    PRESERVE_ONE_BYTE_NULL = 4,
    // Used by WriteUtf8 to replace orphan surrogate code units with the
    // unicode replacement character. Needs to be set to guarantee valid UTF-8
    // output.
    REPLACE_INVALID_UTF8 = 8
  };
 
  // 16-bit character codes.
  int Write(Isolate* isolate, uint16_t* buffer, int start = 0, int length = -1,
            int options = NO_OPTIONS) const;
  // One byte characters.
  int WriteOneByte(Isolate* isolate, uint8_t* buffer, int start = 0,
                   int length = -1, int options = NO_OPTIONS) const;
  // UTF-8 encoded characters.
  int WriteUtf8(Isolate* isolate, char* buffer, int length = -1,
                int* nchars_ref = nullptr, int options = NO_OPTIONS) const;
 
  V8_INLINE static Local<String> Empty(Isolate* isolate);
 
  bool IsExternal() const;
 
  bool IsExternalOneByte() const;
 
  class V8_EXPORT ExternalStringResourceBase {  // NOLINT
   public:
    virtual ~ExternalStringResourceBase() = default;
 
    virtual bool IsCacheable() const { return true; }
 
    // Disallow copying and assigning.
    ExternalStringResourceBase(const ExternalStringResourceBase&) = delete;
    void operator=(const ExternalStringResourceBase&) = delete;
 
   protected:
    ExternalStringResourceBase() = default;
 
    virtual void Dispose() { delete this; }
 
    virtual void Lock() const {}
 
    virtual void Unlock() const {}
 
   private:
    friend class internal::ExternalString;
    friend class v8::String;
    friend class internal::ScopedExternalStringLock;
  };
 
  class V8_EXPORT ExternalStringResource
      : public ExternalStringResourceBase {
   public:
    ~ExternalStringResource() override = default;
 
    virtual const uint16_t* data() const = 0;
 
    virtual size_t length() const = 0;
 
   protected:
    ExternalStringResource() = default;
  };
 
  class V8_EXPORT ExternalOneByteStringResource
      : public ExternalStringResourceBase {
   public:
    ~ExternalOneByteStringResource() override = default;
    virtual const char* data() const = 0;
    virtual size_t length() const = 0;
   protected:
    ExternalOneByteStringResource() = default;
  };
 
  V8_INLINE ExternalStringResourceBase* GetExternalStringResourceBase(
      Encoding* encoding_out) const;
 
  V8_INLINE ExternalStringResource* GetExternalStringResource() const;
 
  const ExternalOneByteStringResource* GetExternalOneByteStringResource() const;
 
  V8_INLINE static String* Cast(v8::Value* obj);
 
  template <int N>
  static V8_WARN_UNUSED_RESULT Local<String> NewFromUtf8Literal(
      Isolate* isolate, const char (&literal)[N],
      NewStringType type = NewStringType::kNormal) {
    static_assert(N <= kMaxLength, "String is too long");
    return NewFromUtf8Literal(isolate, literal, type, N - 1);
  }
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromUtf8(
      Isolate* isolate, const char* data,
      NewStringType type = NewStringType::kNormal, int length = -1);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromOneByte(
      Isolate* isolate, const uint8_t* data,
      NewStringType type = NewStringType::kNormal, int length = -1);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromTwoByte(
      Isolate* isolate, const uint16_t* data,
      NewStringType type = NewStringType::kNormal, int length = -1);
 
  static Local<String> Concat(Isolate* isolate, Local<String> left,
                              Local<String> right);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalTwoByte(
      Isolate* isolate, ExternalStringResource* resource);
 
  bool MakeExternal(ExternalStringResource* resource);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalOneByte(
      Isolate* isolate, ExternalOneByteStringResource* resource);
 
  bool MakeExternal(ExternalOneByteStringResource* resource);
 
  bool CanMakeExternal();
 
  bool StringEquals(Local<String> str);
 
  class V8_EXPORT Utf8Value {
   public:
    Utf8Value(Isolate* isolate, Local<v8::Value> obj);
    ~Utf8Value();
    char* operator*() { return str_; }
    const char* operator*() const { return str_; }
    int length() const { return length_; }
 
    // Disallow copying and assigning.
    Utf8Value(const Utf8Value&) = delete;
    void operator=(const Utf8Value&) = delete;
 
   private:
    char* str_;
    int length_;
  };
 
  class V8_EXPORT Value {
   public:
    Value(Isolate* isolate, Local<v8::Value> obj);
    ~Value();
    uint16_t* operator*() { return str_; }
    const uint16_t* operator*() const { return str_; }
    int length() const { return length_; }
 
    // Disallow copying and assigning.
    Value(const Value&) = delete;
    void operator=(const Value&) = delete;
 
   private:
    uint16_t* str_;
    int length_;
  };
 
 private:
  void VerifyExternalStringResourceBase(ExternalStringResourceBase* v,
                                        Encoding encoding) const;
  void VerifyExternalStringResource(ExternalStringResource* val) const;
  ExternalStringResource* GetExternalStringResourceSlow() const;
  ExternalStringResourceBase* GetExternalStringResourceBaseSlow(
      String::Encoding* encoding_out) const;
 
  static Local<v8::String> NewFromUtf8Literal(Isolate* isolate,
                                              const char* literal,
                                              NewStringType type, int length);
 
  static void CheckCast(v8::Value* obj);
};
 
// Zero-length string specialization (templated string size includes
// terminator).
template <>
inline V8_WARN_UNUSED_RESULT Local<String> String::NewFromUtf8Literal(
    Isolate* isolate, const char (&literal)[1], NewStringType type) {
  return String::Empty(isolate);
}
 
class V8_EXPORT Symbol : public Name {
 public:
  Local<Value> Description() const;
 
  V8_DEPRECATE_SOON("Use Symbol::Description()")
  Local<Value> Name() const { return Description(); }
 
  static Local<Symbol> New(Isolate* isolate,
                           Local<String> description = Local<String>());
 
  static Local<Symbol> For(Isolate* isolate, Local<String> description);
 
  static Local<Symbol> ForApi(Isolate* isolate, Local<String> description);
 
  // Well-known symbols
  static Local<Symbol> GetAsyncIterator(Isolate* isolate);
  static Local<Symbol> GetHasInstance(Isolate* isolate);
  static Local<Symbol> GetIsConcatSpreadable(Isolate* isolate);
  static Local<Symbol> GetIterator(Isolate* isolate);
  static Local<Symbol> GetMatch(Isolate* isolate);
  static Local<Symbol> GetReplace(Isolate* isolate);
  static Local<Symbol> GetSearch(Isolate* isolate);
  static Local<Symbol> GetSplit(Isolate* isolate);
  static Local<Symbol> GetToPrimitive(Isolate* isolate);
  static Local<Symbol> GetToStringTag(Isolate* isolate);
  static Local<Symbol> GetUnscopables(Isolate* isolate);
 
  V8_INLINE static Symbol* Cast(Value* obj);
 
 private:
  Symbol();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Private : public Data {
 public:
  Local<Value> Name() const;
 
  static Local<Private> New(Isolate* isolate,
                            Local<String> name = Local<String>());
 
  static Local<Private> ForApi(Isolate* isolate, Local<String> name);
 
  V8_INLINE static Private* Cast(Data* data);
 
 private:
  Private();
 
  static void CheckCast(Data* that);
};
 
 
class V8_EXPORT Number : public Primitive {
 public:
  double Value() const;
  static Local<Number> New(Isolate* isolate, double value);
  V8_INLINE static Number* Cast(v8::Value* obj);
 private:
  Number();
  static void CheckCast(v8::Value* obj);
};
 
 
class V8_EXPORT Integer : public Number {
 public:
  static Local<Integer> New(Isolate* isolate, int32_t value);
  static Local<Integer> NewFromUnsigned(Isolate* isolate, uint32_t value);
  int64_t Value() const;
  V8_INLINE static Integer* Cast(v8::Value* obj);
 private:
  Integer();
  static void CheckCast(v8::Value* obj);
};
 
 
class V8_EXPORT Int32 : public Integer {
 public:
  int32_t Value() const;
  V8_INLINE static Int32* Cast(v8::Value* obj);
 
 private:
  Int32();
  static void CheckCast(v8::Value* obj);
};
 
 
class V8_EXPORT Uint32 : public Integer {
 public:
  uint32_t Value() const;
  V8_INLINE static Uint32* Cast(v8::Value* obj);
 
 private:
  Uint32();
  static void CheckCast(v8::Value* obj);
};
 
class V8_EXPORT BigInt : public Primitive {
 public:
  static Local<BigInt> New(Isolate* isolate, int64_t value);
  static Local<BigInt> NewFromUnsigned(Isolate* isolate, uint64_t value);
  static MaybeLocal<BigInt> NewFromWords(Local<Context> context, int sign_bit,
                                         int word_count, const uint64_t* words);
 
  uint64_t Uint64Value(bool* lossless = nullptr) const;
 
  int64_t Int64Value(bool* lossless = nullptr) const;
 
  int WordCount() const;
 
  void ToWordsArray(int* sign_bit, int* word_count, uint64_t* words) const;
 
  V8_INLINE static BigInt* Cast(v8::Value* obj);
 
 private:
  BigInt();
  static void CheckCast(v8::Value* obj);
};
 
enum PropertyAttribute {
  None = 0,
  ReadOnly = 1 << 0,
  DontEnum = 1 << 1,
  DontDelete = 1 << 2
};
 
typedef void (*AccessorGetterCallback)(
    Local<String> property,
    const PropertyCallbackInfo<Value>& info);
typedef void (*AccessorNameGetterCallback)(
    Local<Name> property,
    const PropertyCallbackInfo<Value>& info);
 
 
typedef void (*AccessorSetterCallback)(
    Local<String> property,
    Local<Value> value,
    const PropertyCallbackInfo<void>& info);
typedef void (*AccessorNameSetterCallback)(
    Local<Name> property,
    Local<Value> value,
    const PropertyCallbackInfo<void>& info);
 
 
enum AccessControl {
  DEFAULT               = 0,
  ALL_CAN_READ          = 1,
  ALL_CAN_WRITE         = 1 << 1,
  PROHIBITS_OVERWRITING = 1 << 2
};
 
enum PropertyFilter {
  ALL_PROPERTIES = 0,
  ONLY_WRITABLE = 1,
  ONLY_ENUMERABLE = 2,
  ONLY_CONFIGURABLE = 4,
  SKIP_STRINGS = 8,
  SKIP_SYMBOLS = 16
};
 
enum class SideEffectType {
  kHasSideEffect,
  kHasNoSideEffect,
  kHasSideEffectToReceiver
};
 
enum class KeyCollectionMode { kOwnOnly, kIncludePrototypes };
 
enum class IndexFilter { kIncludeIndices, kSkipIndices };
 
enum class KeyConversionMode { kConvertToString, kKeepNumbers, kNoNumbers };
 
enum class IntegrityLevel { kFrozen, kSealed };
 
class V8_EXPORT Object : public Value {
 public:
  V8_WARN_UNUSED_RESULT Maybe<bool> Set(Local<Context> context,
                                        Local<Value> key, Local<Value> value);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Set(Local<Context> context, uint32_t index,
                                        Local<Value> value);
 
  // Implements CreateDataProperty (ECMA-262, 7.3.4).
  //
  // Defines a configurable, writable, enumerable property with the given value
  // on the object unless the property already exists and is not configurable
  // or the object is not extensible.
  //
  // Returns true on success.
  V8_WARN_UNUSED_RESULT Maybe<bool> CreateDataProperty(Local<Context> context,
                                                       Local<Name> key,
                                                       Local<Value> value);
  V8_WARN_UNUSED_RESULT Maybe<bool> CreateDataProperty(Local<Context> context,
                                                       uint32_t index,
                                                       Local<Value> value);
 
  // Implements DefineOwnProperty.
  //
  // In general, CreateDataProperty will be faster, however, does not allow
  // for specifying attributes.
  //
  // Returns true on success.
  V8_WARN_UNUSED_RESULT Maybe<bool> DefineOwnProperty(
      Local<Context> context, Local<Name> key, Local<Value> value,
      PropertyAttribute attributes = None);
 
  // Implements Object.DefineProperty(O, P, Attributes), see Ecma-262 19.1.2.4.
  //
  // The defineProperty function is used to add an own property or
  // update the attributes of an existing own property of an object.
  //
  // Both data and accessor descriptors can be used.
  //
  // In general, CreateDataProperty is faster, however, does not allow
  // for specifying attributes or an accessor descriptor.
  //
  // The PropertyDescriptor can change when redefining a property.
  //
  // Returns true on success.
  V8_WARN_UNUSED_RESULT Maybe<bool> DefineProperty(
      Local<Context> context, Local<Name> key,
      PropertyDescriptor& descriptor);  // NOLINT(runtime/references)
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
                                              Local<Value> key);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
                                              uint32_t index);
 
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute> GetPropertyAttributes(
      Local<Context> context, Local<Value> key);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetOwnPropertyDescriptor(
      Local<Context> context, Local<Name> key);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context,
                                        Local<Value> key);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Delete(Local<Context> context,
                                           Local<Value> key);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context, uint32_t index);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> Delete(Local<Context> context,
                                           uint32_t index);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> SetAccessor(
      Local<Context> context, Local<Name> name,
      AccessorNameGetterCallback getter,
      AccessorNameSetterCallback setter = nullptr,
      MaybeLocal<Value> data = MaybeLocal<Value>(),
      AccessControl settings = DEFAULT, PropertyAttribute attribute = None,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  void SetAccessorProperty(Local<Name> name, Local<Function> getter,
                           Local<Function> setter = Local<Function>(),
                           PropertyAttribute attribute = None,
                           AccessControl settings = DEFAULT);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> SetNativeDataProperty(
      Local<Context> context, Local<Name> name,
      AccessorNameGetterCallback getter,
      AccessorNameSetterCallback setter = nullptr,
      Local<Value> data = Local<Value>(), PropertyAttribute attributes = None,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> SetLazyDataProperty(
      Local<Context> context, Local<Name> name,
      AccessorNameGetterCallback getter, Local<Value> data = Local<Value>(),
      PropertyAttribute attributes = None,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  Maybe<bool> HasPrivate(Local<Context> context, Local<Private> key);
  Maybe<bool> SetPrivate(Local<Context> context, Local<Private> key,
                         Local<Value> value);
  Maybe<bool> DeletePrivate(Local<Context> context, Local<Private> key);
  MaybeLocal<Value> GetPrivate(Local<Context> context, Local<Private> key);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetPropertyNames(
      Local<Context> context);
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetPropertyNames(
      Local<Context> context, KeyCollectionMode mode,
      PropertyFilter property_filter, IndexFilter index_filter,
      KeyConversionMode key_conversion = KeyConversionMode::kKeepNumbers);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetOwnPropertyNames(
      Local<Context> context);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetOwnPropertyNames(
      Local<Context> context, PropertyFilter filter,
      KeyConversionMode key_conversion = KeyConversionMode::kKeepNumbers);
 
  Local<Value> GetPrototype();
 
  V8_WARN_UNUSED_RESULT Maybe<bool> SetPrototype(Local<Context> context,
                                                 Local<Value> prototype);
 
  Local<Object> FindInstanceInPrototypeChain(Local<FunctionTemplate> tmpl);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<String> ObjectProtoToString(
      Local<Context> context);
 
  Local<String> GetConstructorName();
 
  Maybe<bool> SetIntegrityLevel(Local<Context> context, IntegrityLevel level);
 
  int InternalFieldCount();
 
  V8_INLINE static int InternalFieldCount(
      const PersistentBase<Object>& object) {
    return object.val_->InternalFieldCount();
  }
 
  V8_INLINE static int InternalFieldCount(
      const TracedReferenceBase<Object>& object) {
    return object.val_->InternalFieldCount();
  }
 
  V8_INLINE Local<Value> GetInternalField(int index);
 
  void SetInternalField(int index, Local<Value> value);
 
  V8_INLINE void* GetAlignedPointerFromInternalField(int index);
 
  V8_INLINE static void* GetAlignedPointerFromInternalField(
      const PersistentBase<Object>& object, int index) {
    return object.val_->GetAlignedPointerFromInternalField(index);
  }
 
  V8_INLINE static void* GetAlignedPointerFromInternalField(
      const TracedReferenceBase<Object>& object, int index) {
    return object.val_->GetAlignedPointerFromInternalField(index);
  }
 
  void SetAlignedPointerInInternalField(int index, void* value);
  void SetAlignedPointerInInternalFields(int argc, int indices[],
                                         void* values[]);
 
  V8_WARN_UNUSED_RESULT Maybe<bool> HasOwnProperty(Local<Context> context,
                                                   Local<Name> key);
  V8_WARN_UNUSED_RESULT Maybe<bool> HasOwnProperty(Local<Context> context,
                                                   uint32_t index);
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealNamedProperty(Local<Context> context,
                                                         Local<Name> key);
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealIndexedProperty(
      Local<Context> context, uint32_t index);
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealNamedCallbackProperty(
      Local<Context> context, Local<Name> key);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetRealNamedPropertyInPrototypeChain(
      Local<Context> context, Local<Name> key);
 
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute>
  GetRealNamedPropertyAttributesInPrototypeChain(Local<Context> context,
                                                 Local<Name> key);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetRealNamedProperty(
      Local<Context> context, Local<Name> key);
 
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute> GetRealNamedPropertyAttributes(
      Local<Context> context, Local<Name> key);
 
  bool HasNamedLookupInterceptor();
 
  bool HasIndexedLookupInterceptor();
 
  int GetIdentityHash();
 
  // TODO(dcarney): take an isolate and optionally bail out?
  Local<Object> Clone();
 
  Local<Context> CreationContext();
 
  V8_INLINE static Local<Context> CreationContext(
      const PersistentBase<Object>& object) {
    return object.val_->CreationContext();
  }
 
  bool IsCallable();
 
  bool IsConstructor();
 
  bool IsApiWrapper();
 
  bool IsUndetectable();
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> CallAsFunction(Local<Context> context,
                                                         Local<Value> recv,
                                                         int argc,
                                                         Local<Value> argv[]);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> CallAsConstructor(
      Local<Context> context, int argc, Local<Value> argv[]);
 
  Isolate* GetIsolate();
 
  MaybeLocal<Array> PreviewEntries(bool* is_key_value);
 
  static Local<Object> New(Isolate* isolate);
 
  static Local<Object> New(Isolate* isolate, Local<Value> prototype_or_null,
                           Local<Name>* names, Local<Value>* values,
                           size_t length);
 
  V8_INLINE static Object* Cast(Value* obj);
 
 private:
  Object();
  static void CheckCast(Value* obj);
  Local<Value> SlowGetInternalField(int index);
  void* SlowGetAlignedPointerFromInternalField(int index);
};
 
 
class V8_EXPORT Array : public Object {
 public:
  uint32_t Length() const;
 
  static Local<Array> New(Isolate* isolate, int length = 0);
 
  static Local<Array> New(Isolate* isolate, Local<Value>* elements,
                          size_t length);
  V8_INLINE static Array* Cast(Value* obj);
 private:
  Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Map : public Object {
 public:
  size_t Size() const;
  void Clear();
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
                                              Local<Value> key);
  V8_WARN_UNUSED_RESULT MaybeLocal<Map> Set(Local<Context> context,
                                            Local<Value> key,
                                            Local<Value> value);
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context,
                                        Local<Value> key);
  V8_WARN_UNUSED_RESULT Maybe<bool> Delete(Local<Context> context,
                                           Local<Value> key);
 
  Local<Array> AsArray() const;
 
  static Local<Map> New(Isolate* isolate);
 
  V8_INLINE static Map* Cast(Value* obj);
 
 private:
  Map();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Set : public Object {
 public:
  size_t Size() const;
  void Clear();
  V8_WARN_UNUSED_RESULT MaybeLocal<Set> Add(Local<Context> context,
                                            Local<Value> key);
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context,
                                        Local<Value> key);
  V8_WARN_UNUSED_RESULT Maybe<bool> Delete(Local<Context> context,
                                           Local<Value> key);
 
  Local<Array> AsArray() const;
 
  static Local<Set> New(Isolate* isolate);
 
  V8_INLINE static Set* Cast(Value* obj);
 
 private:
  Set();
  static void CheckCast(Value* obj);
};
 
 
template<typename T>
class ReturnValue {
 public:
  template <class S> V8_INLINE ReturnValue(const ReturnValue<S>& that)
      : value_(that.value_) {
    static_assert(std::is_base_of<T, S>::value, "type check");
  }
  // Local setters
  template <typename S>
  V8_INLINE void Set(const Global<S>& handle);
  template <typename S>
  V8_INLINE void Set(const TracedReferenceBase<S>& handle);
  template <typename S>
  V8_INLINE void Set(const Local<S> handle);
  // Fast primitive setters
  V8_INLINE void Set(bool value);
  V8_INLINE void Set(double i);
  V8_INLINE void Set(int32_t i);
  V8_INLINE void Set(uint32_t i);
  // Fast JS primitive setters
  V8_INLINE void SetNull();
  V8_INLINE void SetUndefined();
  V8_INLINE void SetEmptyString();
  // Convenience getter for Isolate
  V8_INLINE Isolate* GetIsolate() const;
 
  // Pointer setter: Uncompilable to prevent inadvertent misuse.
  template <typename S>
  V8_INLINE void Set(S* whatever);
 
  // Getter. Creates a new Local<> so it comes with a certain performance
  // hit. If the ReturnValue was not yet set, this will return the undefined
  // value.
  V8_INLINE Local<Value> Get() const;
 
 private:
  template<class F> friend class ReturnValue;
  template<class F> friend class FunctionCallbackInfo;
  template<class F> friend class PropertyCallbackInfo;
  template <class F, class G, class H>
  friend class PersistentValueMapBase;
  V8_INLINE void SetInternal(internal::Address value) { *value_ = value; }
  V8_INLINE internal::Address GetDefaultValue();
  V8_INLINE explicit ReturnValue(internal::Address* slot);
  internal::Address* value_;
};
 
 
template<typename T>
class FunctionCallbackInfo {
 public:
  V8_INLINE int Length() const;
  V8_INLINE Local<Value> operator[](int i) const;
  V8_INLINE Local<Object> This() const;
  V8_INLINE Local<Object> Holder() const;
  V8_INLINE Local<Value> NewTarget() const;
  V8_INLINE bool IsConstructCall() const;
  V8_INLINE Local<Value> Data() const;
  V8_INLINE Isolate* GetIsolate() const;
  V8_INLINE ReturnValue<T> GetReturnValue() const;
  // This shouldn't be public, but the arm compiler needs it.
  static const int kArgsLength = 6;
 
 protected:
  friend class internal::FunctionCallbackArguments;
  friend class internal::CustomArguments<FunctionCallbackInfo>;
  friend class debug::ConsoleCallArguments;
  static const int kHolderIndex = 0;
  static const int kIsolateIndex = 1;
  static const int kReturnValueDefaultValueIndex = 2;
  static const int kReturnValueIndex = 3;
  static const int kDataIndex = 4;
  static const int kNewTargetIndex = 5;
 
  V8_INLINE FunctionCallbackInfo(internal::Address* implicit_args,
                                 internal::Address* values, int length);
  internal::Address* implicit_args_;
  internal::Address* values_;
  int length_;
};
 
 
template<typename T>
class PropertyCallbackInfo {
 public:
  V8_INLINE Isolate* GetIsolate() const;
 
  V8_INLINE Local<Value> Data() const;
 
  V8_INLINE Local<Object> This() const;
 
  V8_INLINE Local<Object> Holder() const;
 
  V8_INLINE ReturnValue<T> GetReturnValue() const;
 
  V8_INLINE bool ShouldThrowOnError() const;
 
  // This shouldn't be public, but the arm compiler needs it.
  static const int kArgsLength = 7;
 
 protected:
  friend class MacroAssembler;
  friend class internal::PropertyCallbackArguments;
  friend class internal::CustomArguments<PropertyCallbackInfo>;
  static const int kShouldThrowOnErrorIndex = 0;
  static const int kHolderIndex = 1;
  static const int kIsolateIndex = 2;
  static const int kReturnValueDefaultValueIndex = 3;
  static const int kReturnValueIndex = 4;
  static const int kDataIndex = 5;
  static const int kThisIndex = 6;
 
  V8_INLINE PropertyCallbackInfo(internal::Address* args) : args_(args) {}
  internal::Address* args_;
};
 
 
typedef void (*FunctionCallback)(const FunctionCallbackInfo<Value>& info);
 
enum class ConstructorBehavior { kThrow, kAllow };
 
class V8_EXPORT Function : public Object {
 public:
  static MaybeLocal<Function> New(
      Local<Context> context, FunctionCallback callback,
      Local<Value> data = Local<Value>(), int length = 0,
      ConstructorBehavior behavior = ConstructorBehavior::kAllow,
      SideEffectType side_effect_type = SideEffectType::kHasSideEffect);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(
      Local<Context> context, int argc, Local<Value> argv[]) const;
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(
      Local<Context> context) const {
    return NewInstance(context, 0, nullptr);
  }
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstanceWithSideEffectType(
      Local<Context> context, int argc, Local<Value> argv[],
      SideEffectType side_effect_type = SideEffectType::kHasSideEffect) const;
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Call(Local<Context> context,
                                               Local<Value> recv, int argc,
                                               Local<Value> argv[]);
 
  void SetName(Local<String> name);
  Local<Value> GetName() const;
 
  Local<Value> GetInferredName() const;
 
  Local<Value> GetDebugName() const;
 
  Local<Value> GetDisplayName() const;
 
  int GetScriptLineNumber() const;
  int GetScriptColumnNumber() const;
 
  int ScriptId() const;
 
  Local<Value> GetBoundFunction() const;
 
  ScriptOrigin GetScriptOrigin() const;
  V8_INLINE static Function* Cast(Value* obj);
  static const int kLineOffsetNotFound;
 
 private:
  Function();
  static void CheckCast(Value* obj);
};
 
#ifndef V8_PROMISE_INTERNAL_FIELD_COUNT
// The number of required internal fields can be defined by embedder.
#define V8_PROMISE_INTERNAL_FIELD_COUNT 0
#endif
 
class V8_EXPORT Promise : public Object {
 public:
  enum PromiseState { kPending, kFulfilled, kRejected };
 
  class V8_EXPORT Resolver : public Object {
   public:
    static V8_WARN_UNUSED_RESULT MaybeLocal<Resolver> New(
        Local<Context> context);
 
    Local<Promise> GetPromise();
 
    V8_WARN_UNUSED_RESULT Maybe<bool> Resolve(Local<Context> context,
                                              Local<Value> value);
 
    V8_WARN_UNUSED_RESULT Maybe<bool> Reject(Local<Context> context,
                                             Local<Value> value);
 
    V8_INLINE static Resolver* Cast(Value* obj);
 
   private:
    Resolver();
    static void CheckCast(Value* obj);
  };
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Catch(Local<Context> context,
                                                  Local<Function> handler);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Then(Local<Context> context,
                                                 Local<Function> handler);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Then(Local<Context> context,
                                                 Local<Function> on_fulfilled,
                                                 Local<Function> on_rejected);
 
  bool HasHandler();
 
  Local<Value> Result();
 
  PromiseState State();
 
  void MarkAsHandled();
 
  V8_INLINE static Promise* Cast(Value* obj);
 
  static const int kEmbedderFieldCount = V8_PROMISE_INTERNAL_FIELD_COUNT;
 
 private:
  Promise();
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT PropertyDescriptor {
 public:
  // GenericDescriptor
  PropertyDescriptor();
 
  // DataDescriptor
  explicit PropertyDescriptor(Local<Value> value);
 
  // DataDescriptor with writable property
  PropertyDescriptor(Local<Value> value, bool writable);
 
  // AccessorDescriptor
  PropertyDescriptor(Local<Value> get, Local<Value> set);
 
  ~PropertyDescriptor();
 
  Local<Value> value() const;
  bool has_value() const;
 
  Local<Value> get() const;
  bool has_get() const;
  Local<Value> set() const;
  bool has_set() const;
 
  void set_enumerable(bool enumerable);
  bool enumerable() const;
  bool has_enumerable() const;
 
  void set_configurable(bool configurable);
  bool configurable() const;
  bool has_configurable() const;
 
  bool writable() const;
  bool has_writable() const;
 
  struct PrivateData;
  PrivateData* get_private() const { return private_; }
 
  PropertyDescriptor(const PropertyDescriptor&) = delete;
  void operator=(const PropertyDescriptor&) = delete;
 
 private:
  PrivateData* private_;
};
 
class V8_EXPORT Proxy : public Object {
 public:
  Local<Value> GetTarget();
  Local<Value> GetHandler();
  bool IsRevoked();
  void Revoke();
 
  static MaybeLocal<Proxy> New(Local<Context> context,
                               Local<Object> local_target,
                               Local<Object> local_handler);
 
  V8_INLINE static Proxy* Cast(Value* obj);
 
 private:
  Proxy();
  static void CheckCast(Value* obj);
};
 
template <typename T>
class V8_EXPORT MemorySpan {
 public:
  constexpr MemorySpan() = default;
 
  constexpr MemorySpan(T* data, size_t size) : data_(data), size_(size) {}
 
  constexpr T* data() const { return data_; }
  constexpr size_t size() const { return size_; }
 
 private:
  T* data_ = nullptr;
  size_t size_ = 0;
};
 
struct OwnedBuffer {
  std::unique_ptr<const uint8_t[]> buffer;
  size_t size = 0;
  OwnedBuffer(std::unique_ptr<const uint8_t[]> buffer, size_t size)
      : buffer(std::move(buffer)), size(size) {}
  OwnedBuffer() = default;
};
 
// Wrapper around a compiled WebAssembly module, which is potentially shared by
// different WasmModuleObjects.
class V8_EXPORT CompiledWasmModule {
 public:
  OwnedBuffer Serialize();
 
  MemorySpan<const uint8_t> GetWireBytesRef();
 
  const std::string& source_url() const { return source_url_; }
 
 private:
  friend class WasmModuleObject;
  friend class WasmStreaming;
 
  explicit CompiledWasmModule(std::shared_ptr<internal::wasm::NativeModule>,
                              const char* source_url, size_t url_length);
 
  const std::shared_ptr<internal::wasm::NativeModule> native_module_;
  const std::string source_url_;
};
 
// An instance of WebAssembly.Module.
class V8_EXPORT WasmModuleObject : public Object {
 public:
  WasmModuleObject() = delete;
 
  static MaybeLocal<WasmModuleObject> FromCompiledModule(
      Isolate* isolate, const CompiledWasmModule&);
 
  CompiledWasmModule GetCompiledModule();
 
  V8_INLINE static WasmModuleObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT WasmStreaming final {
 public:
  class WasmStreamingImpl;
 
  class Client {
   public:
    virtual ~Client() = default;
    virtual void OnModuleCompiled(CompiledWasmModule compiled_module) = 0;
  };
 
  explicit WasmStreaming(std::unique_ptr<WasmStreamingImpl> impl);
 
  ~WasmStreaming();
 
  void OnBytesReceived(const uint8_t* bytes, size_t size);
 
  void Finish();
 
  void Abort(MaybeLocal<Value> exception);
 
  bool SetCompiledModuleBytes(const uint8_t* bytes, size_t size);
 
  void SetClient(std::shared_ptr<Client> client);
 
  /*
   * Sets the UTF-8 encoded source URL for the {Script} object. This must be
   * called before {Finish}.
   */
  void SetUrl(const char* url, size_t length);
 
  static std::shared_ptr<WasmStreaming> Unpack(Isolate* isolate,
                                               Local<Value> value);
 
 private:
  std::unique_ptr<WasmStreamingImpl> impl_;
};
 
// TODO(mtrofin): when streaming compilation is done, we can rename this
// to simply WasmModuleObjectBuilder
class V8_EXPORT WasmModuleObjectBuilderStreaming final {
 public:
  explicit WasmModuleObjectBuilderStreaming(Isolate* isolate);
  void OnBytesReceived(const uint8_t*, size_t size);
  void Finish();
  void Abort(MaybeLocal<Value> exception);
  Local<Promise> GetPromise();
 
  ~WasmModuleObjectBuilderStreaming() = default;
 
 private:
  WasmModuleObjectBuilderStreaming(const WasmModuleObjectBuilderStreaming&) =
      delete;
  WasmModuleObjectBuilderStreaming(WasmModuleObjectBuilderStreaming&&) =
      default;
  WasmModuleObjectBuilderStreaming& operator=(
      const WasmModuleObjectBuilderStreaming&) = delete;
  WasmModuleObjectBuilderStreaming& operator=(
      WasmModuleObjectBuilderStreaming&&) = default;
  Isolate* isolate_ = nullptr;
 
#if V8_CC_MSVC
 
  Persistent<Promise, CopyablePersistentTraits<Promise>> promise_;
#else
  Persistent<Promise> promise_;
#endif
  std::shared_ptr<internal::wasm::StreamingDecoder> streaming_decoder_;
};
 
#ifndef V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT
// The number of required internal fields can be defined by embedder.
#define V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT 2
#endif
 
 
enum class ArrayBufferCreationMode { kInternalized, kExternalized };
 
class V8_EXPORT BackingStore : public v8::internal::BackingStoreBase {
 public:
  ~BackingStore();
 
  void* Data() const;
 
  size_t ByteLength() const;
 
  bool IsShared() const;
 
  static std::unique_ptr<BackingStore> Reallocate(
      v8::Isolate* isolate, std::unique_ptr<BackingStore> backing_store,
      size_t byte_length);
 
  using DeleterCallback = void (*)(void* data, size_t length,
                                   void* deleter_data);
 
  static void EmptyDeleter(void* data, size_t length, void* deleter_data);
 
 private:
  BackingStore();
};
 
#if !defined(V8_IMMINENT_DEPRECATION_WARNINGS)
// Use v8::BackingStore::DeleterCallback instead.
using BackingStoreDeleterCallback = void (*)(void* data, size_t length,
                                             void* deleter_data);
 
#endif
 
class V8_EXPORT ArrayBuffer : public Object {
 public:
  class V8_EXPORT Allocator { // NOLINT
   public:
    virtual ~Allocator() = default;
 
    virtual void* Allocate(size_t length) = 0;
 
    virtual void* AllocateUninitialized(size_t length) = 0;
 
    virtual void Free(void* data, size_t length) = 0;
 
    virtual void* Reallocate(void* data, size_t old_length, size_t new_length);
 
    enum class AllocationMode { kNormal, kReservation };
 
    static Allocator* NewDefaultAllocator();
  };
 
  class V8_EXPORT Contents { // NOLINT
   public:
    using DeleterCallback = void (*)(void* buffer, size_t length, void* info);
 
    Contents()
        : data_(nullptr),
          byte_length_(0),
          allocation_base_(nullptr),
          allocation_length_(0),
          allocation_mode_(Allocator::AllocationMode::kNormal),
          deleter_(nullptr),
          deleter_data_(nullptr) {}
 
    void* AllocationBase() const { return allocation_base_; }
    size_t AllocationLength() const { return allocation_length_; }
    Allocator::AllocationMode AllocationMode() const {
      return allocation_mode_;
    }
 
    void* Data() const { return data_; }
    size_t ByteLength() const { return byte_length_; }
    DeleterCallback Deleter() const { return deleter_; }
    void* DeleterData() const { return deleter_data_; }
 
   private:
    Contents(void* data, size_t byte_length, void* allocation_base,
             size_t allocation_length,
             Allocator::AllocationMode allocation_mode, DeleterCallback deleter,
             void* deleter_data);
 
    void* data_;
    size_t byte_length_;
    void* allocation_base_;
    size_t allocation_length_;
    Allocator::AllocationMode allocation_mode_;
    DeleterCallback deleter_;
    void* deleter_data_;
 
    friend class ArrayBuffer;
  };
 
 
  size_t ByteLength() const;
 
  static Local<ArrayBuffer> New(Isolate* isolate, size_t byte_length);
 
  V8_DEPRECATE_SOON(
      "Use the version that takes a BackingStore. "
      "See http://crbug.com/v8/9908.")
  static Local<ArrayBuffer> New(
      Isolate* isolate, void* data, size_t byte_length,
      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
 
  static Local<ArrayBuffer> New(Isolate* isolate,
                                std::shared_ptr<BackingStore> backing_store);
 
  static std::unique_ptr<BackingStore> NewBackingStore(Isolate* isolate,
                                                       size_t byte_length);
  static std::unique_ptr<BackingStore> NewBackingStore(
      void* data, size_t byte_length, v8::BackingStore::DeleterCallback deleter,
      void* deleter_data);
 
  V8_DEPRECATE_SOON(
      "With v8::BackingStore externalized ArrayBuffers are "
      "the same as ordinary ArrayBuffers. See http://crbug.com/v8/9908.")
  bool IsExternal() const;
 
  bool IsDetachable() const;
 
  void Detach();
 
  V8_DEPRECATE_SOON(
      "Use GetBackingStore or Detach. See http://crbug.com/v8/9908.")
  Contents Externalize();
 
  V8_DEPRECATE_SOON("This will be removed together with IsExternal.")
  void Externalize(const std::shared_ptr<BackingStore>& backing_store);
 
  V8_DEPRECATE_SOON("Use GetBackingStore. See http://crbug.com/v8/9908.")
  Contents GetContents();
 
  std::shared_ptr<BackingStore> GetBackingStore();
 
  V8_INLINE static ArrayBuffer* Cast(Value* obj);
 
  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
  static const int kEmbedderFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
 
 private:
  ArrayBuffer();
  static void CheckCast(Value* obj);
  Contents GetContents(bool externalize);
};
 
 
#ifndef V8_ARRAY_BUFFER_VIEW_INTERNAL_FIELD_COUNT
// The number of required internal fields can be defined by embedder.
#define V8_ARRAY_BUFFER_VIEW_INTERNAL_FIELD_COUNT 2
#endif
 
 
class V8_EXPORT ArrayBufferView : public Object {
 public:
  Local<ArrayBuffer> Buffer();
  size_t ByteOffset();
  size_t ByteLength();
 
  size_t CopyContents(void* dest, size_t byte_length);
 
  bool HasBuffer() const;
 
  V8_INLINE static ArrayBufferView* Cast(Value* obj);
 
  static const int kInternalFieldCount =
      V8_ARRAY_BUFFER_VIEW_INTERNAL_FIELD_COUNT;
  static const int kEmbedderFieldCount =
      V8_ARRAY_BUFFER_VIEW_INTERNAL_FIELD_COUNT;
 
 private:
  ArrayBufferView();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT TypedArray : public ArrayBufferView {
 public:
  /*
   * The largest typed array size that can be constructed using New.
   */
  static constexpr size_t kMaxLength = internal::kApiSystemPointerSize == 4
                                           ? internal::kSmiMaxValue
                                           : 0xFFFFFFFF;
 
  size_t Length();
 
  V8_INLINE static TypedArray* Cast(Value* obj);
 
 private:
  TypedArray();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Uint8Array : public TypedArray {
 public:
  static Local<Uint8Array> New(Local<ArrayBuffer> array_buffer,
                               size_t byte_offset, size_t length);
  static Local<Uint8Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                               size_t byte_offset, size_t length);
  V8_INLINE static Uint8Array* Cast(Value* obj);
 
 private:
  Uint8Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Uint8ClampedArray : public TypedArray {
 public:
  static Local<Uint8ClampedArray> New(Local<ArrayBuffer> array_buffer,
                                      size_t byte_offset, size_t length);
  static Local<Uint8ClampedArray> New(
      Local<SharedArrayBuffer> shared_array_buffer, size_t byte_offset,
      size_t length);
  V8_INLINE static Uint8ClampedArray* Cast(Value* obj);
 
 private:
  Uint8ClampedArray();
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT Int8Array : public TypedArray {
 public:
  static Local<Int8Array> New(Local<ArrayBuffer> array_buffer,
                              size_t byte_offset, size_t length);
  static Local<Int8Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                              size_t byte_offset, size_t length);
  V8_INLINE static Int8Array* Cast(Value* obj);
 
 private:
  Int8Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Uint16Array : public TypedArray {
 public:
  static Local<Uint16Array> New(Local<ArrayBuffer> array_buffer,
                                size_t byte_offset, size_t length);
  static Local<Uint16Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                size_t byte_offset, size_t length);
  V8_INLINE static Uint16Array* Cast(Value* obj);
 
 private:
  Uint16Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Int16Array : public TypedArray {
 public:
  static Local<Int16Array> New(Local<ArrayBuffer> array_buffer,
                               size_t byte_offset, size_t length);
  static Local<Int16Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                               size_t byte_offset, size_t length);
  V8_INLINE static Int16Array* Cast(Value* obj);
 
 private:
  Int16Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Uint32Array : public TypedArray {
 public:
  static Local<Uint32Array> New(Local<ArrayBuffer> array_buffer,
                                size_t byte_offset, size_t length);
  static Local<Uint32Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                size_t byte_offset, size_t length);
  V8_INLINE static Uint32Array* Cast(Value* obj);
 
 private:
  Uint32Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Int32Array : public TypedArray {
 public:
  static Local<Int32Array> New(Local<ArrayBuffer> array_buffer,
                               size_t byte_offset, size_t length);
  static Local<Int32Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                               size_t byte_offset, size_t length);
  V8_INLINE static Int32Array* Cast(Value* obj);
 
 private:
  Int32Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Float32Array : public TypedArray {
 public:
  static Local<Float32Array> New(Local<ArrayBuffer> array_buffer,
                                 size_t byte_offset, size_t length);
  static Local<Float32Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                 size_t byte_offset, size_t length);
  V8_INLINE static Float32Array* Cast(Value* obj);
 
 private:
  Float32Array();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT Float64Array : public TypedArray {
 public:
  static Local<Float64Array> New(Local<ArrayBuffer> array_buffer,
                                 size_t byte_offset, size_t length);
  static Local<Float64Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                 size_t byte_offset, size_t length);
  V8_INLINE static Float64Array* Cast(Value* obj);
 
 private:
  Float64Array();
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT BigInt64Array : public TypedArray {
 public:
  static Local<BigInt64Array> New(Local<ArrayBuffer> array_buffer,
                                  size_t byte_offset, size_t length);
  static Local<BigInt64Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                  size_t byte_offset, size_t length);
  V8_INLINE static BigInt64Array* Cast(Value* obj);
 
 private:
  BigInt64Array();
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT BigUint64Array : public TypedArray {
 public:
  static Local<BigUint64Array> New(Local<ArrayBuffer> array_buffer,
                                   size_t byte_offset, size_t length);
  static Local<BigUint64Array> New(Local<SharedArrayBuffer> shared_array_buffer,
                                   size_t byte_offset, size_t length);
  V8_INLINE static BigUint64Array* Cast(Value* obj);
 
 private:
  BigUint64Array();
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT DataView : public ArrayBufferView {
 public:
  static Local<DataView> New(Local<ArrayBuffer> array_buffer,
                             size_t byte_offset, size_t length);
  static Local<DataView> New(Local<SharedArrayBuffer> shared_array_buffer,
                             size_t byte_offset, size_t length);
  V8_INLINE static DataView* Cast(Value* obj);
 
 private:
  DataView();
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT SharedArrayBuffer : public Object {
 public:
  class V8_EXPORT Contents {  // NOLINT
   public:
    using Allocator = v8::ArrayBuffer::Allocator;
    using DeleterCallback = void (*)(void* buffer, size_t length, void* info);
 
    Contents()
        : data_(nullptr),
          byte_length_(0),
          allocation_base_(nullptr),
          allocation_length_(0),
          allocation_mode_(Allocator::AllocationMode::kNormal),
          deleter_(nullptr),
          deleter_data_(nullptr) {}
 
    void* AllocationBase() const { return allocation_base_; }
    size_t AllocationLength() const { return allocation_length_; }
    Allocator::AllocationMode AllocationMode() const {
      return allocation_mode_;
    }
 
    void* Data() const { return data_; }
    size_t ByteLength() const { return byte_length_; }
    DeleterCallback Deleter() const { return deleter_; }
    void* DeleterData() const { return deleter_data_; }
 
   private:
    Contents(void* data, size_t byte_length, void* allocation_base,
             size_t allocation_length,
             Allocator::AllocationMode allocation_mode, DeleterCallback deleter,
             void* deleter_data);
 
    void* data_;
    size_t byte_length_;
    void* allocation_base_;
    size_t allocation_length_;
    Allocator::AllocationMode allocation_mode_;
    DeleterCallback deleter_;
    void* deleter_data_;
 
    friend class SharedArrayBuffer;
  };
 
  size_t ByteLength() const;
 
  static Local<SharedArrayBuffer> New(Isolate* isolate, size_t byte_length);
 
  V8_DEPRECATE_SOON(
      "Use the version that takes a BackingStore. "
      "See http://crbug.com/v8/9908.")
  static Local<SharedArrayBuffer> New(
      Isolate* isolate, void* data, size_t byte_length,
      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
 
  static Local<SharedArrayBuffer> New(
      Isolate* isolate, std::shared_ptr<BackingStore> backing_store);
 
  static std::unique_ptr<BackingStore> NewBackingStore(Isolate* isolate,
                                                       size_t byte_length);
  static std::unique_ptr<BackingStore> NewBackingStore(
      void* data, size_t byte_length, v8::BackingStore::DeleterCallback deleter,
      void* deleter_data);
 
  V8_DEPRECATED(
      "Use the version that takes a BackingStore. "
      "See http://crbug.com/v8/9908.")
  static Local<SharedArrayBuffer> New(
      Isolate* isolate, const SharedArrayBuffer::Contents&,
      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
 
  V8_DEPRECATE_SOON(
      "With v8::BackingStore externalized SharedArrayBuffers are the same "
      "as ordinary SharedArrayBuffers. See http://crbug.com/v8/9908.")
  bool IsExternal() const;
 
  V8_DEPRECATE_SOON(
      "Use GetBackingStore or Detach. See http://crbug.com/v8/9908.")
  Contents Externalize();
 
  V8_DEPRECATE_SOON("This will be removed together with IsExternal.")
  void Externalize(const std::shared_ptr<BackingStore>& backing_store);
 
  V8_DEPRECATE_SOON("Use GetBackingStore. See http://crbug.com/v8/9908.")
  Contents GetContents();
 
  std::shared_ptr<BackingStore> GetBackingStore();
 
  V8_INLINE static SharedArrayBuffer* Cast(Value* obj);
 
  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
 
 private:
  SharedArrayBuffer();
  static void CheckCast(Value* obj);
  Contents GetContents(bool externalize);
};
 
 
class V8_EXPORT Date : public Object {
 public:
  static V8_WARN_UNUSED_RESULT MaybeLocal<Value> New(Local<Context> context,
                                                     double time);
 
  double ValueOf() const;
 
  V8_INLINE static Date* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT NumberObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, double value);
 
  double ValueOf() const;
 
  V8_INLINE static NumberObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT BigIntObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, int64_t value);
 
  Local<BigInt> ValueOf() const;
 
  V8_INLINE static BigIntObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT BooleanObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, bool value);
 
  bool ValueOf() const;
 
  V8_INLINE static BooleanObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT StringObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, Local<String> value);
 
  Local<String> ValueOf() const;
 
  V8_INLINE static StringObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT SymbolObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, Local<Symbol> value);
 
  Local<Symbol> ValueOf() const;
 
  V8_INLINE static SymbolObject* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
 
class V8_EXPORT RegExp : public Object {
 public:
  enum Flags {
    kNone = 0,
    kGlobal = 1 << 0,
    kIgnoreCase = 1 << 1,
    kMultiline = 1 << 2,
    kSticky = 1 << 3,
    kUnicode = 1 << 4,
    kDotAll = 1 << 5,
  };
 
  static constexpr int kFlagCount = 6;
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<RegExp> New(Local<Context> context,
                                                      Local<String> pattern,
                                                      Flags flags);
 
  static V8_WARN_UNUSED_RESULT MaybeLocal<RegExp> NewWithBacktrackLimit(
      Local<Context> context, Local<String> pattern, Flags flags,
      uint32_t backtrack_limit);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> Exec(Local<Context> context,
                                                Local<String> subject);
 
  Local<String> GetSource() const;
 
  Flags GetFlags() const;
 
  V8_INLINE static RegExp* Cast(Value* obj);
 
 private:
  static void CheckCast(Value* obj);
};
 
class V8_EXPORT External : public Value {
 public:
  static Local<External> New(Isolate* isolate, void* value);
  V8_INLINE static External* Cast(Value* obj);
  void* Value() const;
 private:
  static void CheckCast(v8::Value* obj);
};
 
#define V8_INTRINSICS_LIST(F)                      \
  F(ArrayProto_entries, array_entries_iterator)    \
  F(ArrayProto_forEach, array_for_each_iterator)   \
  F(ArrayProto_keys, array_keys_iterator)          \
  F(ArrayProto_values, array_values_iterator)      \
  F(ErrorPrototype, initial_error_prototype)       \
  F(IteratorPrototype, initial_iterator_prototype) \
  F(ObjProto_valueOf, object_value_of_function)
 
enum Intrinsic {
#define V8_DECL_INTRINSIC(name, iname) k##name,
  V8_INTRINSICS_LIST(V8_DECL_INTRINSIC)
#undef V8_DECL_INTRINSIC
};
 
 
// --- Templates ---
 
 
class V8_EXPORT Template : public Data {
 public:
  void Set(Local<Name> name, Local<Data> value,
           PropertyAttribute attributes = None);
  void SetPrivate(Local<Private> name, Local<Data> value,
                  PropertyAttribute attributes = None);
  V8_INLINE void Set(Isolate* isolate, const char* name, Local<Data> value);
 
  void SetAccessorProperty(
     Local<Name> name,
     Local<FunctionTemplate> getter = Local<FunctionTemplate>(),
     Local<FunctionTemplate> setter = Local<FunctionTemplate>(),
     PropertyAttribute attribute = None,
     AccessControl settings = DEFAULT);
 
  void SetNativeDataProperty(
      Local<String> name, AccessorGetterCallback getter,
      AccessorSetterCallback setter = nullptr,
      // TODO(dcarney): gcc can't handle Local below
      Local<Value> data = Local<Value>(), PropertyAttribute attribute = None,
      Local<AccessorSignature> signature = Local<AccessorSignature>(),
      AccessControl settings = DEFAULT,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
  void SetNativeDataProperty(
      Local<Name> name, AccessorNameGetterCallback getter,
      AccessorNameSetterCallback setter = nullptr,
      // TODO(dcarney): gcc can't handle Local below
      Local<Value> data = Local<Value>(), PropertyAttribute attribute = None,
      Local<AccessorSignature> signature = Local<AccessorSignature>(),
      AccessControl settings = DEFAULT,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  void SetLazyDataProperty(
      Local<Name> name, AccessorNameGetterCallback getter,
      Local<Value> data = Local<Value>(), PropertyAttribute attribute = None,
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  void SetIntrinsicDataProperty(Local<Name> name, Intrinsic intrinsic,
                                PropertyAttribute attribute = None);
 
 private:
  Template();
 
  friend class ObjectTemplate;
  friend class FunctionTemplate;
};
 
// TODO(dcarney): Replace GenericNamedPropertyFooCallback with just
// NamedPropertyFooCallback.
 
typedef void (*GenericNamedPropertyGetterCallback)(
    Local<Name> property, const PropertyCallbackInfo<Value>& info);
 
typedef void (*GenericNamedPropertySetterCallback)(
    Local<Name> property, Local<Value> value,
    const PropertyCallbackInfo<Value>& info);
 
typedef void (*GenericNamedPropertyQueryCallback)(
    Local<Name> property, const PropertyCallbackInfo<Integer>& info);
 
typedef void (*GenericNamedPropertyDeleterCallback)(
    Local<Name> property, const PropertyCallbackInfo<Boolean>& info);
 
typedef void (*GenericNamedPropertyEnumeratorCallback)(
    const PropertyCallbackInfo<Array>& info);
 
typedef void (*GenericNamedPropertyDefinerCallback)(
    Local<Name> property, const PropertyDescriptor& desc,
    const PropertyCallbackInfo<Value>& info);
 
typedef void (*GenericNamedPropertyDescriptorCallback)(
    Local<Name> property, const PropertyCallbackInfo<Value>& info);
 
typedef void (*IndexedPropertyGetterCallback)(
    uint32_t index,
    const PropertyCallbackInfo<Value>& info);
 
typedef void (*IndexedPropertySetterCallback)(
    uint32_t index,
    Local<Value> value,
    const PropertyCallbackInfo<Value>& info);
 
typedef void (*IndexedPropertyQueryCallback)(
    uint32_t index,
    const PropertyCallbackInfo<Integer>& info);
 
typedef void (*IndexedPropertyDeleterCallback)(
    uint32_t index,
    const PropertyCallbackInfo<Boolean>& info);
 
typedef void (*IndexedPropertyEnumeratorCallback)(
    const PropertyCallbackInfo<Array>& info);
 
typedef void (*IndexedPropertyDefinerCallback)(
    uint32_t index, const PropertyDescriptor& desc,
    const PropertyCallbackInfo<Value>& info);
 
typedef void (*IndexedPropertyDescriptorCallback)(
    uint32_t index, const PropertyCallbackInfo<Value>& info);
 
enum AccessType {
  ACCESS_GET,
  ACCESS_SET,
  ACCESS_HAS,
  ACCESS_DELETE,
  ACCESS_KEYS
};
 
 
typedef bool (*AccessCheckCallback)(Local<Context> accessing_context,
                                    Local<Object> accessed_object,
                                    Local<Value> data);
 
class CFunction;
class V8_EXPORT FunctionTemplate : public Template {
 public:
  static Local<FunctionTemplate> New(
      Isolate* isolate, FunctionCallback callback = nullptr,
      Local<Value> data = Local<Value>(),
      Local<Signature> signature = Local<Signature>(), int length = 0,
      ConstructorBehavior behavior = ConstructorBehavior::kAllow,
      SideEffectType side_effect_type = SideEffectType::kHasSideEffect,
      const CFunction* c_function = nullptr);
 
  static Local<FunctionTemplate> NewWithCache(
      Isolate* isolate, FunctionCallback callback,
      Local<Private> cache_property, Local<Value> data = Local<Value>(),
      Local<Signature> signature = Local<Signature>(), int length = 0,
      SideEffectType side_effect_type = SideEffectType::kHasSideEffect);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Function> GetFunction(
      Local<Context> context);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewRemoteInstance();
 
  void SetCallHandler(
      FunctionCallback callback, Local<Value> data = Local<Value>(),
      SideEffectType side_effect_type = SideEffectType::kHasSideEffect,
      const CFunction* c_function = nullptr);
 
  void SetLength(int length);
 
  Local<ObjectTemplate> InstanceTemplate();
 
  void Inherit(Local<FunctionTemplate> parent);
 
  Local<ObjectTemplate> PrototypeTemplate();
 
  void SetPrototypeProviderTemplate(Local<FunctionTemplate> prototype_provider);
 
  void SetClassName(Local<String> name);
 
 
  void SetAcceptAnyReceiver(bool value);
 
  void ReadOnlyPrototype();
 
  void RemovePrototype();
 
  bool HasInstance(Local<Value> object);
 
  V8_INLINE static FunctionTemplate* Cast(Data* data);
 
 private:
  FunctionTemplate();
 
  static void CheckCast(Data* that);
  friend class Context;
  friend class ObjectTemplate;
};
 
enum class PropertyHandlerFlags {
  kNone = 0,
 
  kAllCanRead = 1,
 
  kNonMasking = 1 << 1,
 
  kOnlyInterceptStrings = 1 << 2,
 
  kHasNoSideEffect = 1 << 3,
};
 
struct NamedPropertyHandlerConfiguration {
  NamedPropertyHandlerConfiguration(
      GenericNamedPropertyGetterCallback getter,
      GenericNamedPropertySetterCallback setter,
      GenericNamedPropertyQueryCallback query,
      GenericNamedPropertyDeleterCallback deleter,
      GenericNamedPropertyEnumeratorCallback enumerator,
      GenericNamedPropertyDefinerCallback definer,
      GenericNamedPropertyDescriptorCallback descriptor,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        definer(definer),
        descriptor(descriptor),
        data(data),
        flags(flags) {}
 
  NamedPropertyHandlerConfiguration(
      GenericNamedPropertyGetterCallback getter = nullptr,
      GenericNamedPropertySetterCallback setter = nullptr,
      GenericNamedPropertyQueryCallback query = nullptr,
      GenericNamedPropertyDeleterCallback deleter = nullptr,
      GenericNamedPropertyEnumeratorCallback enumerator = nullptr,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        definer(nullptr),
        descriptor(nullptr),
        data(data),
        flags(flags) {}
 
  NamedPropertyHandlerConfiguration(
      GenericNamedPropertyGetterCallback getter,
      GenericNamedPropertySetterCallback setter,
      GenericNamedPropertyDescriptorCallback descriptor,
      GenericNamedPropertyDeleterCallback deleter,
      GenericNamedPropertyEnumeratorCallback enumerator,
      GenericNamedPropertyDefinerCallback definer,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(nullptr),
        deleter(deleter),
        enumerator(enumerator),
        definer(definer),
        descriptor(descriptor),
        data(data),
        flags(flags) {}
 
  GenericNamedPropertyGetterCallback getter;
  GenericNamedPropertySetterCallback setter;
  GenericNamedPropertyQueryCallback query;
  GenericNamedPropertyDeleterCallback deleter;
  GenericNamedPropertyEnumeratorCallback enumerator;
  GenericNamedPropertyDefinerCallback definer;
  GenericNamedPropertyDescriptorCallback descriptor;
  Local<Value> data;
  PropertyHandlerFlags flags;
};
 
 
struct IndexedPropertyHandlerConfiguration {
  IndexedPropertyHandlerConfiguration(
      IndexedPropertyGetterCallback getter,
      IndexedPropertySetterCallback setter, IndexedPropertyQueryCallback query,
      IndexedPropertyDeleterCallback deleter,
      IndexedPropertyEnumeratorCallback enumerator,
      IndexedPropertyDefinerCallback definer,
      IndexedPropertyDescriptorCallback descriptor,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        definer(definer),
        descriptor(descriptor),
        data(data),
        flags(flags) {}
 
  IndexedPropertyHandlerConfiguration(
      IndexedPropertyGetterCallback getter = nullptr,
      IndexedPropertySetterCallback setter = nullptr,
      IndexedPropertyQueryCallback query = nullptr,
      IndexedPropertyDeleterCallback deleter = nullptr,
      IndexedPropertyEnumeratorCallback enumerator = nullptr,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        definer(nullptr),
        descriptor(nullptr),
        data(data),
        flags(flags) {}
 
  IndexedPropertyHandlerConfiguration(
      IndexedPropertyGetterCallback getter,
      IndexedPropertySetterCallback setter,
      IndexedPropertyDescriptorCallback descriptor,
      IndexedPropertyDeleterCallback deleter,
      IndexedPropertyEnumeratorCallback enumerator,
      IndexedPropertyDefinerCallback definer,
      Local<Value> data = Local<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(nullptr),
        deleter(deleter),
        enumerator(enumerator),
        definer(definer),
        descriptor(descriptor),
        data(data),
        flags(flags) {}
 
  IndexedPropertyGetterCallback getter;
  IndexedPropertySetterCallback setter;
  IndexedPropertyQueryCallback query;
  IndexedPropertyDeleterCallback deleter;
  IndexedPropertyEnumeratorCallback enumerator;
  IndexedPropertyDefinerCallback definer;
  IndexedPropertyDescriptorCallback descriptor;
  Local<Value> data;
  PropertyHandlerFlags flags;
};
 
 
class V8_EXPORT ObjectTemplate : public Template {
 public:
  static Local<ObjectTemplate> New(
      Isolate* isolate,
      Local<FunctionTemplate> constructor = Local<FunctionTemplate>());
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(Local<Context> context);
 
  void SetAccessor(
      Local<String> name, AccessorGetterCallback getter,
      AccessorSetterCallback setter = nullptr,
      Local<Value> data = Local<Value>(), AccessControl settings = DEFAULT,
      PropertyAttribute attribute = None,
      Local<AccessorSignature> signature = Local<AccessorSignature>(),
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
  void SetAccessor(
      Local<Name> name, AccessorNameGetterCallback getter,
      AccessorNameSetterCallback setter = nullptr,
      Local<Value> data = Local<Value>(), AccessControl settings = DEFAULT,
      PropertyAttribute attribute = None,
      Local<AccessorSignature> signature = Local<AccessorSignature>(),
      SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect,
      SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect);
 
  void SetHandler(const NamedPropertyHandlerConfiguration& configuration);
 
  // TODO(dcarney): deprecate
  void SetIndexedPropertyHandler(
      IndexedPropertyGetterCallback getter,
      IndexedPropertySetterCallback setter = nullptr,
      IndexedPropertyQueryCallback query = nullptr,
      IndexedPropertyDeleterCallback deleter = nullptr,
      IndexedPropertyEnumeratorCallback enumerator = nullptr,
      Local<Value> data = Local<Value>()) {
    SetHandler(IndexedPropertyHandlerConfiguration(getter, setter, query,
                                                   deleter, enumerator, data));
  }
 
  void SetHandler(const IndexedPropertyHandlerConfiguration& configuration);
 
  void SetCallAsFunctionHandler(FunctionCallback callback,
                                Local<Value> data = Local<Value>());
 
  void MarkAsUndetectable();
 
  void SetAccessCheckCallback(AccessCheckCallback callback,
                              Local<Value> data = Local<Value>());
 
  void SetAccessCheckCallbackAndHandler(
      AccessCheckCallback callback,
      const NamedPropertyHandlerConfiguration& named_handler,
      const IndexedPropertyHandlerConfiguration& indexed_handler,
      Local<Value> data = Local<Value>());
 
  int InternalFieldCount();
 
  void SetInternalFieldCount(int value);
 
  bool IsImmutableProto();
 
  void SetImmutableProto();
 
  V8_INLINE static ObjectTemplate* Cast(Data* data);
 
 private:
  ObjectTemplate();
  static Local<ObjectTemplate> New(internal::Isolate* isolate,
                                   Local<FunctionTemplate> constructor);
  static void CheckCast(Data* that);
  friend class FunctionTemplate;
};
 
class V8_EXPORT Signature : public Data {
 public:
  static Local<Signature> New(
      Isolate* isolate,
      Local<FunctionTemplate> receiver = Local<FunctionTemplate>());
 
  V8_INLINE static Signature* Cast(Data* data);
 
 private:
  Signature();
 
  static void CheckCast(Data* that);
};
 
 
class V8_EXPORT AccessorSignature : public Data {
 public:
  static Local<AccessorSignature> New(
      Isolate* isolate,
      Local<FunctionTemplate> receiver = Local<FunctionTemplate>());
 
  V8_INLINE static AccessorSignature* Cast(Data* data);
 
 private:
  AccessorSignature();
 
  static void CheckCast(Data* that);
};
 
 
// --- Extensions ---
 
class V8_EXPORT Extension {  // NOLINT
 public:
  // Note that the strings passed into this constructor must live as long
  // as the Extension itself.
  Extension(const char* name, const char* source = nullptr, int dep_count = 0,
            const char** deps = nullptr, int source_length = -1);
  virtual ~Extension() { delete source_; }
  virtual Local<FunctionTemplate> GetNativeFunctionTemplate(
      Isolate* isolate, Local<String> name) {
    return Local<FunctionTemplate>();
  }
 
  const char* name() const { return name_; }
  size_t source_length() const { return source_length_; }
  const String::ExternalOneByteStringResource* source() const {
    return source_;
  }
  int dependency_count() const { return dep_count_; }
  const char** dependencies() const { return deps_; }
  void set_auto_enable(bool value) { auto_enable_ = value; }
  bool auto_enable() { return auto_enable_; }
 
  // Disallow copying and assigning.
  Extension(const Extension&) = delete;
  void operator=(const Extension&) = delete;
 
 private:
  const char* name_;
  size_t source_length_;  // expected to initialize before source_
  String::ExternalOneByteStringResource* source_;
  int dep_count_;
  const char** deps_;
  bool auto_enable_;
};
 
void V8_EXPORT RegisterExtension(std::unique_ptr<Extension>);
 
// --- Statics ---
 
V8_INLINE Local<Primitive> Undefined(Isolate* isolate);
V8_INLINE Local<Primitive> Null(Isolate* isolate);
V8_INLINE Local<Boolean> True(Isolate* isolate);
V8_INLINE Local<Boolean> False(Isolate* isolate);
 
class V8_EXPORT ResourceConstraints {
 public:
  void ConfigureDefaultsFromHeapSize(size_t initial_heap_size_in_bytes,
                                     size_t maximum_heap_size_in_bytes);
 
  void ConfigureDefaults(uint64_t physical_memory,
                         uint64_t virtual_memory_limit);
 
  uint32_t* stack_limit() const { return stack_limit_; }
  void set_stack_limit(uint32_t* value) { stack_limit_ = value; }
 
  size_t code_range_size_in_bytes() const { return code_range_size_; }
  void set_code_range_size_in_bytes(size_t limit) { code_range_size_ = limit; }
 
  size_t max_old_generation_size_in_bytes() const {
    return max_old_generation_size_;
  }
  void set_max_old_generation_size_in_bytes(size_t limit) {
    max_old_generation_size_ = limit;
  }
 
  size_t max_young_generation_size_in_bytes() const {
    return max_young_generation_size_;
  }
  void set_max_young_generation_size_in_bytes(size_t limit) {
    max_young_generation_size_ = limit;
  }
 
  size_t initial_old_generation_size_in_bytes() const {
    return initial_old_generation_size_;
  }
  void set_initial_old_generation_size_in_bytes(size_t initial_size) {
    initial_old_generation_size_ = initial_size;
  }
 
  size_t initial_young_generation_size_in_bytes() const {
    return initial_young_generation_size_;
  }
  void set_initial_young_generation_size_in_bytes(size_t initial_size) {
    initial_young_generation_size_ = initial_size;
  }
 
  V8_DEPRECATE_SOON("Use code_range_size_in_bytes.")
  size_t code_range_size() const { return code_range_size_ / kMB; }
  V8_DEPRECATE_SOON("Use set_code_range_size_in_bytes.")
  void set_code_range_size(size_t limit_in_mb) {
    code_range_size_ = limit_in_mb * kMB;
  }
  V8_DEPRECATE_SOON("Use max_young_generation_size_in_bytes.")
  size_t max_semi_space_size_in_kb() const;
  V8_DEPRECATE_SOON("Use set_max_young_generation_size_in_bytes.")
  void set_max_semi_space_size_in_kb(size_t limit_in_kb);
  V8_DEPRECATE_SOON("Use max_old_generation_size_in_bytes.")
  size_t max_old_space_size() const { return max_old_generation_size_ / kMB; }
  V8_DEPRECATE_SOON("Use set_max_old_generation_size_in_bytes.")
  void set_max_old_space_size(size_t limit_in_mb) {
    max_old_generation_size_ = limit_in_mb * kMB;
  }
  V8_DEPRECATE_SOON("Zone does not pool memory any more.")
  size_t max_zone_pool_size() const { return max_zone_pool_size_; }
  V8_DEPRECATE_SOON("Zone does not pool memory any more.")
  void set_max_zone_pool_size(size_t bytes) { max_zone_pool_size_ = bytes; }
 
 private:
  static constexpr size_t kMB = 1048576u;
  size_t code_range_size_ = 0;
  size_t max_old_generation_size_ = 0;
  size_t max_young_generation_size_ = 0;
  size_t max_zone_pool_size_ = 0;
  size_t initial_old_generation_size_ = 0;
  size_t initial_young_generation_size_ = 0;
  uint32_t* stack_limit_ = nullptr;
};
 
 
// --- Exceptions ---
 
 
typedef void (*FatalErrorCallback)(const char* location, const char* message);
 
typedef void (*OOMErrorCallback)(const char* location, bool is_heap_oom);
 
typedef void (*DcheckErrorCallback)(const char* file, int line,
                                    const char* message);
 
typedef void (*MessageCallback)(Local<Message> message, Local<Value> data);
 
// --- Tracing ---
 
typedef void (*LogEventCallback)(const char* name, int event);
 
class V8_EXPORT Exception {
 public:
  static Local<Value> RangeError(Local<String> message);
  static Local<Value> ReferenceError(Local<String> message);
  static Local<Value> SyntaxError(Local<String> message);
  static Local<Value> TypeError(Local<String> message);
  static Local<Value> WasmCompileError(Local<String> message);
  static Local<Value> WasmLinkError(Local<String> message);
  static Local<Value> WasmRuntimeError(Local<String> message);
  static Local<Value> Error(Local<String> message);
 
  static Local<Message> CreateMessage(Isolate* isolate, Local<Value> exception);
 
  static Local<StackTrace> GetStackTrace(Local<Value> exception);
};
 
 
// --- Counters Callbacks ---
 
typedef int* (*CounterLookupCallback)(const char* name);
 
typedef void* (*CreateHistogramCallback)(const char* name,
                                         int min,
                                         int max,
                                         size_t buckets);
 
typedef void (*AddHistogramSampleCallback)(void* histogram, int sample);
 
// --- Crashkeys Callback ---
enum class CrashKeyId {
  kIsolateAddress,
  kReadonlySpaceFirstPageAddress,
  kMapSpaceFirstPageAddress,
  kCodeSpaceFirstPageAddress,
  kDumpType,
};
 
typedef void (*AddCrashKeyCallback)(CrashKeyId id, const std::string& value);
 
// --- Enter/Leave Script Callback ---
typedef void (*BeforeCallEnteredCallback)(Isolate*);
typedef void (*CallCompletedCallback)(Isolate*);
 
typedef MaybeLocal<Promise> (*HostImportModuleDynamicallyCallback)(
    Local<Context> context, Local<ScriptOrModule> referrer,
    Local<String> specifier);
 
typedef void (*HostInitializeImportMetaObjectCallback)(Local<Context> context,
                                                       Local<Module> module,
                                                       Local<Object> meta);
 
typedef MaybeLocal<Value> (*PrepareStackTraceCallback)(Local<Context> context,
                                                       Local<Value> error,
                                                       Local<Array> sites);
 
enum class PromiseHookType { kInit, kResolve, kBefore, kAfter };
 
typedef void (*PromiseHook)(PromiseHookType type, Local<Promise> promise,
                            Local<Value> parent);
 
// --- Promise Reject Callback ---
enum PromiseRejectEvent {
  kPromiseRejectWithNoHandler = 0,
  kPromiseHandlerAddedAfterReject = 1,
  kPromiseRejectAfterResolved = 2,
  kPromiseResolveAfterResolved = 3,
};
 
class PromiseRejectMessage {
 public:
  PromiseRejectMessage(Local<Promise> promise, PromiseRejectEvent event,
                       Local<Value> value)
      : promise_(promise), event_(event), value_(value) {}
 
  V8_INLINE Local<Promise> GetPromise() const { return promise_; }
  V8_INLINE PromiseRejectEvent GetEvent() const { return event_; }
  V8_INLINE Local<Value> GetValue() const { return value_; }
 
 private:
  Local<Promise> promise_;
  PromiseRejectEvent event_;
  Local<Value> value_;
};
 
typedef void (*PromiseRejectCallback)(PromiseRejectMessage message);
 
// --- Microtasks Callbacks ---
V8_DEPRECATE_SOON("Use *WithData version.")
typedef void (*MicrotasksCompletedCallback)(Isolate*);
typedef void (*MicrotasksCompletedCallbackWithData)(Isolate*, void*);
typedef void (*MicrotaskCallback)(void* data);
 
enum class MicrotasksPolicy { kExplicit, kScoped, kAuto };
 
class V8_EXPORT MicrotaskQueue {
 public:
  static std::unique_ptr<MicrotaskQueue> New(
      Isolate* isolate, MicrotasksPolicy policy = MicrotasksPolicy::kAuto);
 
  virtual ~MicrotaskQueue() = default;
 
  virtual void EnqueueMicrotask(Isolate* isolate,
                                Local<Function> microtask) = 0;
 
  virtual void EnqueueMicrotask(v8::Isolate* isolate,
                                MicrotaskCallback callback,
                                void* data = nullptr) = 0;
 
  virtual void AddMicrotasksCompletedCallback(
      MicrotasksCompletedCallbackWithData callback, void* data = nullptr) = 0;
 
  virtual void RemoveMicrotasksCompletedCallback(
      MicrotasksCompletedCallbackWithData callback, void* data = nullptr) = 0;
 
  virtual void PerformCheckpoint(Isolate* isolate) = 0;
 
  virtual bool IsRunningMicrotasks() const = 0;
 
  virtual int GetMicrotasksScopeDepth() const = 0;
 
  MicrotaskQueue(const MicrotaskQueue&) = delete;
  MicrotaskQueue& operator=(const MicrotaskQueue&) = delete;
 
 private:
  friend class internal::MicrotaskQueue;
  MicrotaskQueue() = default;
};
 
class V8_EXPORT MicrotasksScope {
 public:
  enum Type { kRunMicrotasks, kDoNotRunMicrotasks };
 
  MicrotasksScope(Isolate* isolate, Type type);
  MicrotasksScope(Isolate* isolate, MicrotaskQueue* microtask_queue, Type type);
  ~MicrotasksScope();
 
  static void PerformCheckpoint(Isolate* isolate);
 
  static int GetCurrentDepth(Isolate* isolate);
 
  static bool IsRunningMicrotasks(Isolate* isolate);
 
  // Prevent copying.
  MicrotasksScope(const MicrotasksScope&) = delete;
  MicrotasksScope& operator=(const MicrotasksScope&) = delete;
 
 private:
  internal::Isolate* const isolate_;
  internal::MicrotaskQueue* const microtask_queue_;
  bool run_;
};
 
 
// --- Failed Access Check Callback ---
typedef void (*FailedAccessCheckCallback)(Local<Object> target,
                                          AccessType type,
                                          Local<Value> data);
 
// --- AllowCodeGenerationFromStrings callbacks ---
 
typedef bool (*AllowCodeGenerationFromStringsCallback)(Local<Context> context,
                                                       Local<String> source);
 
struct ModifyCodeGenerationFromStringsResult {
  // If true, proceed with the codegen algorithm. Otherwise, block it.
  bool codegen_allowed = false;
  // Overwrite the original source with this string, if present.
  // Use the original source if empty.
  // This field is considered only if codegen_allowed is true.
  MaybeLocal<String> modified_source;
};
 
typedef ModifyCodeGenerationFromStringsResult (
    *ModifyCodeGenerationFromStringsCallback)(Local<Context> context,
                                              Local<Value> source);
 
// --- WebAssembly compilation callbacks ---
typedef bool (*ExtensionCallback)(const FunctionCallbackInfo<Value>&);
 
typedef bool (*AllowWasmCodeGenerationCallback)(Local<Context> context,
                                                Local<String> source);
 
// --- Callback for APIs defined on v8-supported objects, but implemented
// by the embedder. Example: WebAssembly.{compile|instantiate}Streaming ---
typedef void (*ApiImplementationCallback)(const FunctionCallbackInfo<Value>&);
 
// --- Callback for WebAssembly.compileStreaming ---
typedef void (*WasmStreamingCallback)(const FunctionCallbackInfo<Value>&);
 
// --- Callback for checking if WebAssembly threads are enabled ---
typedef bool (*WasmThreadsEnabledCallback)(Local<Context> context);
 
// --- Callback for loading source map file for Wasm profiling support
typedef Local<String> (*WasmLoadSourceMapCallback)(Isolate* isolate,
                                                   const char* name);
 
// --- Callback for checking if WebAssembly Simd is enabled ---
typedef bool (*WasmSimdEnabledCallback)(Local<Context> context);
 
// --- Garbage Collection Callbacks ---
 
enum GCType {
  kGCTypeScavenge = 1 << 0,
  kGCTypeMarkSweepCompact = 1 << 1,
  kGCTypeIncrementalMarking = 1 << 2,
  kGCTypeProcessWeakCallbacks = 1 << 3,
  kGCTypeAll = kGCTypeScavenge | kGCTypeMarkSweepCompact |
               kGCTypeIncrementalMarking | kGCTypeProcessWeakCallbacks
};
 
enum GCCallbackFlags {
  kNoGCCallbackFlags = 0,
  kGCCallbackFlagConstructRetainedObjectInfos = 1 << 1,
  kGCCallbackFlagForced = 1 << 2,
  kGCCallbackFlagSynchronousPhantomCallbackProcessing = 1 << 3,
  kGCCallbackFlagCollectAllAvailableGarbage = 1 << 4,
  kGCCallbackFlagCollectAllExternalMemory = 1 << 5,
  kGCCallbackScheduleIdleGarbageCollection = 1 << 6,
};
 
typedef void (*GCCallback)(GCType type, GCCallbackFlags flags);
 
typedef void (*InterruptCallback)(Isolate* isolate, void* data);
 
typedef size_t (*NearHeapLimitCallback)(void* data, size_t current_heap_limit,
                                        size_t initial_heap_limit);
 
class V8_EXPORT SharedMemoryStatistics {
 public:
  SharedMemoryStatistics();
  size_t read_only_space_size() { return read_only_space_size_; }
  size_t read_only_space_used_size() { return read_only_space_used_size_; }
  size_t read_only_space_physical_size() {
    return read_only_space_physical_size_;
  }
 
 private:
  size_t read_only_space_size_;
  size_t read_only_space_used_size_;
  size_t read_only_space_physical_size_;
 
  friend class V8;
  friend class internal::ReadOnlyHeap;
};
 
class V8_EXPORT HeapStatistics {
 public:
  HeapStatistics();
  size_t total_heap_size() { return total_heap_size_; }
  size_t total_heap_size_executable() { return total_heap_size_executable_; }
  size_t total_physical_size() { return total_physical_size_; }
  size_t total_available_size() { return total_available_size_; }
  size_t total_global_handles_size() { return total_global_handles_size_; }
  size_t used_global_handles_size() { return used_global_handles_size_; }
  size_t used_heap_size() { return used_heap_size_; }
  size_t heap_size_limit() { return heap_size_limit_; }
  size_t malloced_memory() { return malloced_memory_; }
  size_t external_memory() { return external_memory_; }
  size_t peak_malloced_memory() { return peak_malloced_memory_; }
  size_t number_of_native_contexts() { return number_of_native_contexts_; }
  size_t number_of_detached_contexts() { return number_of_detached_contexts_; }
 
  size_t does_zap_garbage() { return does_zap_garbage_; }
 
 private:
  size_t total_heap_size_;
  size_t total_heap_size_executable_;
  size_t total_physical_size_;
  size_t total_available_size_;
  size_t used_heap_size_;
  size_t heap_size_limit_;
  size_t malloced_memory_;
  size_t external_memory_;
  size_t peak_malloced_memory_;
  bool does_zap_garbage_;
  size_t number_of_native_contexts_;
  size_t number_of_detached_contexts_;
  size_t total_global_handles_size_;
  size_t used_global_handles_size_;
 
  friend class V8;
  friend class Isolate;
};
 
 
class V8_EXPORT HeapSpaceStatistics {
 public:
  HeapSpaceStatistics();
  const char* space_name() { return space_name_; }
  size_t space_size() { return space_size_; }
  size_t space_used_size() { return space_used_size_; }
  size_t space_available_size() { return space_available_size_; }
  size_t physical_space_size() { return physical_space_size_; }
 
 private:
  const char* space_name_;
  size_t space_size_;
  size_t space_used_size_;
  size_t space_available_size_;
  size_t physical_space_size_;
 
  friend class Isolate;
};
 
 
class V8_EXPORT HeapObjectStatistics {
 public:
  HeapObjectStatistics();
  const char* object_type() { return object_type_; }
  const char* object_sub_type() { return object_sub_type_; }
  size_t object_count() { return object_count_; }
  size_t object_size() { return object_size_; }
 
 private:
  const char* object_type_;
  const char* object_sub_type_;
  size_t object_count_;
  size_t object_size_;
 
  friend class Isolate;
};
 
class V8_EXPORT HeapCodeStatistics {
 public:
  HeapCodeStatistics();
  size_t code_and_metadata_size() { return code_and_metadata_size_; }
  size_t bytecode_and_metadata_size() { return bytecode_and_metadata_size_; }
  size_t external_script_source_size() { return external_script_source_size_; }
 
 private:
  size_t code_and_metadata_size_;
  size_t bytecode_and_metadata_size_;
  size_t external_script_source_size_;
 
  friend class Isolate;
};
 
struct JitCodeEvent {
  enum EventType {
    CODE_ADDED,
    CODE_MOVED,
    CODE_REMOVED,
    CODE_ADD_LINE_POS_INFO,
    CODE_START_LINE_INFO_RECORDING,
    CODE_END_LINE_INFO_RECORDING
  };
  // Definition of the code position type. The "POSITION" type means the place
  // in the source code which are of interest when making stack traces to
  // pin-point the source location of a stack frame as close as possible.
  // The "STATEMENT_POSITION" means the place at the beginning of each
  // statement, and is used to indicate possible break locations.
  enum PositionType { POSITION, STATEMENT_POSITION };
 
  // There are two different kinds of JitCodeEvents, one for JIT code generated
  // by the optimizing compiler, and one for byte code generated for the
  // interpreter.  For JIT_CODE events, the |code_start| member of the event
  // points to the beginning of jitted assembly code, while for BYTE_CODE
  // events, |code_start| points to the first bytecode of the interpreted
  // function.
  enum CodeType { BYTE_CODE, JIT_CODE };
 
  // Type of event.
  EventType type;
  CodeType code_type;
  // Start of the instructions.
  void* code_start;
  // Size of the instructions.
  size_t code_len;
  // Script info for CODE_ADDED event.
  Local<UnboundScript> script;
  // User-defined data for *_LINE_INFO_* event. It's used to hold the source
  // code line information which is returned from the
  // CODE_START_LINE_INFO_RECORDING event. And it's passed to subsequent
  // CODE_ADD_LINE_POS_INFO and CODE_END_LINE_INFO_RECORDING events.
  void* user_data;
 
  struct name_t {
    // Name of the object associated with the code, note that the string is not
    // zero-terminated.
    const char* str;
    // Number of chars in str.
    size_t len;
  };
 
  struct line_info_t {
    // PC offset
    size_t offset;
    // Code position
    size_t pos;
    // The position type.
    PositionType position_type;
  };
 
  struct wasm_source_info_t {
    // Source file name.
    const char* filename;
    // Length of filename.
    size_t filename_size;
    // Line number table, which maps offsets of JITted code to line numbers of
    // source file.
    const line_info_t* line_number_table;
    // Number of entries in the line number table.
    size_t line_number_table_size;
  };
 
  wasm_source_info_t* wasm_source_info;
 
  union {
    // Only valid for CODE_ADDED.
    struct name_t name;
 
    // Only valid for CODE_ADD_LINE_POS_INFO
    struct line_info_t line_info;
 
    // New location of instructions. Only valid for CODE_MOVED.
    void* new_code_start;
  };
 
  Isolate* isolate;
};
 
enum RAILMode : unsigned {
  // Response performance mode: In this mode very low virtual machine latency
  // is provided. V8 will try to avoid JavaScript execution interruptions.
  // Throughput may be throttled.
  PERFORMANCE_RESPONSE,
  // Animation performance mode: In this mode low virtual machine latency is
  // provided. V8 will try to avoid as many JavaScript execution interruptions
  // as possible. Throughput may be throttled. This is the default mode.
  PERFORMANCE_ANIMATION,
  // Idle performance mode: The embedder is idle. V8 can complete deferred work
  // in this mode.
  PERFORMANCE_IDLE,
  // Load performance mode: In this mode high throughput is provided. V8 may
  // turn off latency optimizations.
  PERFORMANCE_LOAD
};
 
enum JitCodeEventOptions {
  kJitCodeEventDefault = 0,
  // Generate callbacks for already existent code.
  kJitCodeEventEnumExisting = 1
};
 
 
typedef void (*JitCodeEventHandler)(const JitCodeEvent* event);
 
#if defined(V8_OS_WIN)
typedef int (*UnhandledExceptionCallback)(
    _EXCEPTION_POINTERS* exception_pointers);
#endif
 
class V8_EXPORT ExternalResourceVisitor {  // NOLINT
 public:
  virtual ~ExternalResourceVisitor() = default;
  virtual void VisitExternalString(Local<String> string) {}
};
 
 
class V8_EXPORT PersistentHandleVisitor {  // NOLINT
 public:
  virtual ~PersistentHandleVisitor() = default;
  virtual void VisitPersistentHandle(Persistent<Value>* value,
                                     uint16_t class_id) {}
};
 
enum class MemoryPressureLevel { kNone, kModerate, kCritical };
 
class V8_EXPORT EmbedderHeapTracer {
 public:
  using EmbedderStackState = cppgc::EmbedderStackState;
 
  enum TraceFlags : uint64_t {
    kNoFlags = 0,
    kReduceMemory = 1 << 0,
    kForced = 1 << 2,
  };
 
  class V8_EXPORT TracedGlobalHandleVisitor {
   public:
    virtual ~TracedGlobalHandleVisitor() = default;
    virtual void VisitTracedGlobalHandle(const TracedGlobal<Value>& handle) {}
    virtual void VisitTracedReference(const TracedReference<Value>& handle) {}
  };
 
  struct TraceSummary {
    double time = 0.0;
 
    size_t allocated_size = 0;
  };
 
  virtual ~EmbedderHeapTracer() = default;
 
  void IterateTracedGlobalHandles(TracedGlobalHandleVisitor* visitor);
 
  void SetStackStart(void* stack_start);
 
  void NotifyEmptyEmbedderStack();
 
  virtual void RegisterV8References(
      const std::vector<std::pair<void*, void*> >& embedder_fields) = 0;
 
  void RegisterEmbedderReference(const TracedReferenceBase<v8::Data>& ref);
 
  virtual void TracePrologue(TraceFlags flags) {}
 
  virtual bool AdvanceTracing(double deadline_in_ms) = 0;
 
  /*
   * Returns true if there no more tracing work to be done (see AdvanceTracing)
   * and false otherwise.
   */
  virtual bool IsTracingDone() = 0;
 
  virtual void TraceEpilogue(TraceSummary* trace_summary) {}
 
  virtual void EnterFinalPause(EmbedderStackState stack_state) = 0;
 
  /*
   * Called by the embedder to request immediate finalization of the currently
   * running tracing phase that has been started with TracePrologue and not
   * yet finished with TraceEpilogue.
   *
   * Will be a noop when currently not in tracing.
   *
   * This is an experimental feature.
   */
  void FinalizeTracing();
 
  virtual bool IsRootForNonTracingGC(
      const v8::TracedReference<v8::Value>& handle);
  virtual bool IsRootForNonTracingGC(const v8::TracedGlobal<v8::Value>& handle);
 
  virtual void ResetHandleInNonTracingGC(
      const v8::TracedReference<v8::Value>& handle);
 
  /*
   * Called by the embedder to immediately perform a full garbage collection.
   *
   * Should only be used in testing code.
   */
  void GarbageCollectionForTesting(EmbedderStackState stack_state);
 
  /*
   * Called by the embedder to signal newly allocated or freed memory. Not bound
   * to tracing phases. Embedders should trade off when increments are reported
   * as V8 may consult global heuristics on whether to trigger garbage
   * collection on this change.
   */
  void IncreaseAllocatedSize(size_t bytes);
  void DecreaseAllocatedSize(size_t bytes);
 
  /*
   * Returns the v8::Isolate this tracer is attached too and |nullptr| if it
   * is not attached to any v8::Isolate.
   */
  v8::Isolate* isolate() const { return isolate_; }
 
 protected:
  v8::Isolate* isolate_ = nullptr;
 
  friend class internal::LocalEmbedderHeapTracer;
};
 
struct SerializeInternalFieldsCallback {
  typedef StartupData (*CallbackFunction)(Local<Object> holder, int index,
                                          void* data);
  SerializeInternalFieldsCallback(CallbackFunction function = nullptr,
                                  void* data_arg = nullptr)
      : callback(function), data(data_arg) {}
  CallbackFunction callback;
  void* data;
};
// Note that these fields are called "internal fields" in the API and called
// "embedder fields" within V8.
typedef SerializeInternalFieldsCallback SerializeEmbedderFieldsCallback;
 
struct DeserializeInternalFieldsCallback {
  typedef void (*CallbackFunction)(Local<Object> holder, int index,
                                   StartupData payload, void* data);
  DeserializeInternalFieldsCallback(CallbackFunction function = nullptr,
                                    void* data_arg = nullptr)
      : callback(function), data(data_arg) {}
  void (*callback)(Local<Object> holder, int index, StartupData payload,
                   void* data);
  void* data;
};
typedef DeserializeInternalFieldsCallback DeserializeEmbedderFieldsCallback;
 
enum class MeasureMemoryMode { kSummary, kDetailed };
 
enum class MeasureMemoryExecution { kDefault, kEager };
 
class V8_EXPORT MeasureMemoryDelegate {
 public:
  virtual ~MeasureMemoryDelegate() = default;
 
  virtual bool ShouldMeasure(Local<Context> context) = 0;
 
  virtual void MeasurementComplete(
      const std::vector<std::pair<Local<Context>, size_t>>&
          context_sizes_in_bytes,
      size_t unattributed_size_in_bytes) = 0;
 
  static std::unique_ptr<MeasureMemoryDelegate> Default(
      Isolate* isolate, Local<Context> context,
      Local<Promise::Resolver> promise_resolver, MeasureMemoryMode mode);
};
 
class V8_EXPORT Isolate {
 public:
  struct CreateParams {
    CreateParams()
        : code_event_handler(nullptr),
          snapshot_blob(nullptr),
          counter_lookup_callback(nullptr),
          create_histogram_callback(nullptr),
          add_histogram_sample_callback(nullptr),
          array_buffer_allocator(nullptr),
          array_buffer_allocator_shared(),
          external_references(nullptr),
          allow_atomics_wait(true),
          only_terminate_in_safe_scope(false),
          embedder_wrapper_type_index(-1),
          embedder_wrapper_object_index(-1) {}
 
    JitCodeEventHandler code_event_handler;
 
    ResourceConstraints constraints;
 
    StartupData* snapshot_blob;
 
 
    CounterLookupCallback counter_lookup_callback;
 
    CreateHistogramCallback create_histogram_callback;
    AddHistogramSampleCallback add_histogram_sample_callback;
 
    ArrayBuffer::Allocator* array_buffer_allocator;
    std::shared_ptr<ArrayBuffer::Allocator> array_buffer_allocator_shared;
 
    const intptr_t* external_references;
 
    bool allow_atomics_wait;
 
    bool only_terminate_in_safe_scope;
 
    int embedder_wrapper_type_index;
    int embedder_wrapper_object_index;
  };
 
 
  class V8_EXPORT Scope {
   public:
    explicit Scope(Isolate* isolate) : isolate_(isolate) {
      isolate->Enter();
    }
 
    ~Scope() { isolate_->Exit(); }
 
    // Prevent copying of Scope objects.
    Scope(const Scope&) = delete;
    Scope& operator=(const Scope&) = delete;
 
   private:
    Isolate* const isolate_;
  };
 
 
  class V8_EXPORT DisallowJavascriptExecutionScope {
   public:
    enum OnFailure { CRASH_ON_FAILURE, THROW_ON_FAILURE, DUMP_ON_FAILURE };
 
    DisallowJavascriptExecutionScope(Isolate* isolate, OnFailure on_failure);
    ~DisallowJavascriptExecutionScope();
 
    // Prevent copying of Scope objects.
    DisallowJavascriptExecutionScope(const DisallowJavascriptExecutionScope&) =
        delete;
    DisallowJavascriptExecutionScope& operator=(
        const DisallowJavascriptExecutionScope&) = delete;
 
   private:
    OnFailure on_failure_;
    void* internal_;
  };
 
 
  class V8_EXPORT AllowJavascriptExecutionScope {
   public:
    explicit AllowJavascriptExecutionScope(Isolate* isolate);
    ~AllowJavascriptExecutionScope();
 
    // Prevent copying of Scope objects.
    AllowJavascriptExecutionScope(const AllowJavascriptExecutionScope&) =
        delete;
    AllowJavascriptExecutionScope& operator=(
        const AllowJavascriptExecutionScope&) = delete;
 
   private:
    void* internal_throws_;
    void* internal_assert_;
    void* internal_dump_;
  };
 
  class V8_EXPORT SuppressMicrotaskExecutionScope {
   public:
    explicit SuppressMicrotaskExecutionScope(
        Isolate* isolate, MicrotaskQueue* microtask_queue = nullptr);
    ~SuppressMicrotaskExecutionScope();
 
    // Prevent copying of Scope objects.
    SuppressMicrotaskExecutionScope(const SuppressMicrotaskExecutionScope&) =
        delete;
    SuppressMicrotaskExecutionScope& operator=(
        const SuppressMicrotaskExecutionScope&) = delete;
 
   private:
    internal::Isolate* const isolate_;
    internal::MicrotaskQueue* const microtask_queue_;
    internal::Address previous_stack_height_;
 
    friend class internal::ThreadLocalTop;
  };
 
  class V8_EXPORT SafeForTerminationScope {
   public:
    explicit SafeForTerminationScope(v8::Isolate* isolate);
    ~SafeForTerminationScope();
 
    // Prevent copying of Scope objects.
    SafeForTerminationScope(const SafeForTerminationScope&) = delete;
    SafeForTerminationScope& operator=(const SafeForTerminationScope&) = delete;
 
   private:
    internal::Isolate* isolate_;
    bool prev_value_;
  };
 
  enum GarbageCollectionType {
    kFullGarbageCollection,
    kMinorGarbageCollection
  };
 
  enum UseCounterFeature {
    kUseAsm = 0,
    kBreakIterator = 1,
    kLegacyConst = 2,
    kMarkDequeOverflow = 3,
    kStoreBufferOverflow = 4,
    kSlotsBufferOverflow = 5,
    kObjectObserve = 6,
    kForcedGC = 7,
    kSloppyMode = 8,
    kStrictMode = 9,
    kStrongMode = 10,
    kRegExpPrototypeStickyGetter = 11,
    kRegExpPrototypeToString = 12,
    kRegExpPrototypeUnicodeGetter = 13,
    kIntlV8Parse = 14,
    kIntlPattern = 15,
    kIntlResolved = 16,
    kPromiseChain = 17,
    kPromiseAccept = 18,
    kPromiseDefer = 19,
    kHtmlCommentInExternalScript = 20,
    kHtmlComment = 21,
    kSloppyModeBlockScopedFunctionRedefinition = 22,
    kForInInitializer = 23,
    kArrayProtectorDirtied = 24,
    kArraySpeciesModified = 25,
    kArrayPrototypeConstructorModified = 26,
    kArrayInstanceProtoModified = 27,
    kArrayInstanceConstructorModified = 28,
    kLegacyFunctionDeclaration = 29,
    kRegExpPrototypeSourceGetter = 30,
    kRegExpPrototypeOldFlagGetter = 31,
    kDecimalWithLeadingZeroInStrictMode = 32,
    kLegacyDateParser = 33,
    kDefineGetterOrSetterWouldThrow = 34,
    kFunctionConstructorReturnedUndefined = 35,
    kAssigmentExpressionLHSIsCallInSloppy = 36,
    kAssigmentExpressionLHSIsCallInStrict = 37,
    kPromiseConstructorReturnedUndefined = 38,
    kConstructorNonUndefinedPrimitiveReturn = 39,
    kLabeledExpressionStatement = 40,
    kLineOrParagraphSeparatorAsLineTerminator = 41,
    kIndexAccessor = 42,
    kErrorCaptureStackTrace = 43,
    kErrorPrepareStackTrace = 44,
    kErrorStackTraceLimit = 45,
    kWebAssemblyInstantiation = 46,
    kDeoptimizerDisableSpeculation = 47,
    kArrayPrototypeSortJSArrayModifiedPrototype = 48,
    kFunctionTokenOffsetTooLongForToString = 49,
    kWasmSharedMemory = 50,
    kWasmThreadOpcodes = 51,
    kAtomicsNotify = 52,
    kAtomicsWake = 53,
    kCollator = 54,
    kNumberFormat = 55,
    kDateTimeFormat = 56,
    kPluralRules = 57,
    kRelativeTimeFormat = 58,
    kLocale = 59,
    kListFormat = 60,
    kSegmenter = 61,
    kStringLocaleCompare = 62,
    kStringToLocaleUpperCase = 63,
    kStringToLocaleLowerCase = 64,
    kNumberToLocaleString = 65,
    kDateToLocaleString = 66,
    kDateToLocaleDateString = 67,
    kDateToLocaleTimeString = 68,
    kAttemptOverrideReadOnlyOnPrototypeSloppy = 69,
    kAttemptOverrideReadOnlyOnPrototypeStrict = 70,
    kOptimizedFunctionWithOneShotBytecode = 71,
    kRegExpMatchIsTrueishOnNonJSRegExp = 72,
    kRegExpMatchIsFalseishOnJSRegExp = 73,
    kDateGetTimezoneOffset = 74,  // Unused.
    kStringNormalize = 75,
    kCallSiteAPIGetFunctionSloppyCall = 76,
    kCallSiteAPIGetThisSloppyCall = 77,
    kRegExpMatchAllWithNonGlobalRegExp = 78,
    kRegExpExecCalledOnSlowRegExp = 79,
    kRegExpReplaceCalledOnSlowRegExp = 80,
    kDisplayNames = 81,
    kSharedArrayBufferConstructed = 82,
    kArrayPrototypeHasElements = 83,
    kObjectPrototypeHasElements = 84,
    kNumberFormatStyleUnit = 85,
    kDateTimeFormatRange = 86,
    kDateTimeFormatDateTimeStyle = 87,
    kBreakIteratorTypeWord = 88,
    kBreakIteratorTypeLine = 89,
    kInvalidatedArrayBufferDetachingProtector = 90,
    kInvalidatedArrayConstructorProtector = 91,
    kInvalidatedArrayIteratorLookupChainProtector = 92,
    kInvalidatedArraySpeciesLookupChainProtector = 93,
    kInvalidatedIsConcatSpreadableLookupChainProtector = 94,
    kInvalidatedMapIteratorLookupChainProtector = 95,
    kInvalidatedNoElementsProtector = 96,
    kInvalidatedPromiseHookProtector = 97,
    kInvalidatedPromiseResolveLookupChainProtector = 98,
    kInvalidatedPromiseSpeciesLookupChainProtector = 99,
    kInvalidatedPromiseThenLookupChainProtector = 100,
    kInvalidatedRegExpSpeciesLookupChainProtector = 101,
    kInvalidatedSetIteratorLookupChainProtector = 102,
    kInvalidatedStringIteratorLookupChainProtector = 103,
    kInvalidatedStringLengthOverflowLookupChainProtector = 104,
    kInvalidatedTypedArraySpeciesLookupChainProtector = 105,
    kWasmSimdOpcodes = 106,
    kVarRedeclaredCatchBinding = 107,
 
    // If you add new values here, you'll also need to update Chromium's:
    // web_feature.mojom, use_counter_callback.cc, and enums.xml. V8 changes to
    // this list need to be landed first, then changes on the Chromium side.
    kUseCounterFeatureCount  // This enum value must be last.
  };
 
  enum MessageErrorLevel {
    kMessageLog = (1 << 0),
    kMessageDebug = (1 << 1),
    kMessageInfo = (1 << 2),
    kMessageError = (1 << 3),
    kMessageWarning = (1 << 4),
    kMessageAll = kMessageLog | kMessageDebug | kMessageInfo | kMessageError |
                  kMessageWarning,
  };
 
  typedef void (*UseCounterCallback)(Isolate* isolate,
                                     UseCounterFeature feature);
 
  static Isolate* Allocate();
 
  static void Initialize(Isolate* isolate, const CreateParams& params);
 
  static Isolate* New(const CreateParams& params);
 
  static Isolate* GetCurrent();
 
  void ClearKeptObjects();
 
  typedef bool (*AbortOnUncaughtExceptionCallback)(Isolate*);
  void SetAbortOnUncaughtExceptionCallback(
      AbortOnUncaughtExceptionCallback callback);
 
  void SetHostImportModuleDynamicallyCallback(
      HostImportModuleDynamicallyCallback callback);
 
  void SetHostInitializeImportMetaObjectCallback(
      HostInitializeImportMetaObjectCallback callback);
 
  void SetPrepareStackTraceCallback(PrepareStackTraceCallback callback);
 
  void MemoryPressureNotification(MemoryPressureLevel level);
 
  void Enter();
 
  void Exit();
 
  void Dispose();
 
  void DumpAndResetStats();
 
  void DiscardThreadSpecificMetadata();
 
  V8_INLINE void SetData(uint32_t slot, void* data);
 
  V8_INLINE void* GetData(uint32_t slot);
 
  V8_INLINE static uint32_t GetNumberOfDataSlots();
 
  template <class T>
  V8_INLINE MaybeLocal<T> GetDataFromSnapshotOnce(size_t index);
 
  void GetHeapStatistics(HeapStatistics* heap_statistics);
 
  size_t NumberOfHeapSpaces();
 
  bool GetHeapSpaceStatistics(HeapSpaceStatistics* space_statistics,
                              size_t index);
 
  size_t NumberOfTrackedHeapObjectTypes();
 
  bool GetHeapObjectStatisticsAtLastGC(HeapObjectStatistics* object_statistics,
                                       size_t type_index);
 
  bool GetHeapCodeAndMetadataStatistics(HeapCodeStatistics* object_statistics);
 
  bool MeasureMemory(
      std::unique_ptr<MeasureMemoryDelegate> delegate,
      MeasureMemoryExecution execution = MeasureMemoryExecution::kDefault);
 
  V8_DEPRECATE_SOON("Use the version with a delegate")
  MaybeLocal<Promise> MeasureMemory(Local<Context> context,
                                    MeasureMemoryMode mode);
 
  void GetStackSample(const RegisterState& state, void** frames,
                      size_t frames_limit, SampleInfo* sample_info);
 
  V8_INLINE int64_t
      AdjustAmountOfExternalAllocatedMemory(int64_t change_in_bytes);
 
  size_t NumberOfPhantomHandleResetsSinceLastCall();
 
  HeapProfiler* GetHeapProfiler();
 
  void SetIdle(bool is_idle);
 
  ArrayBuffer::Allocator* GetArrayBufferAllocator();
 
  bool InContext();
 
  Local<Context> GetCurrentContext();
 
  V8_DEPRECATED("Use GetEnteredOrMicrotaskContext().")
  Local<Context> GetEnteredContext();
 
  Local<Context> GetEnteredOrMicrotaskContext();
 
  Local<Context> GetIncumbentContext();
 
  Local<Value> ThrowException(Local<Value> exception);
 
  typedef void (*GCCallback)(Isolate* isolate, GCType type,
                             GCCallbackFlags flags);
  typedef void (*GCCallbackWithData)(Isolate* isolate, GCType type,
                                     GCCallbackFlags flags, void* data);
 
  void AddGCPrologueCallback(GCCallbackWithData callback, void* data = nullptr,
                             GCType gc_type_filter = kGCTypeAll);
  void AddGCPrologueCallback(GCCallback callback,
                             GCType gc_type_filter = kGCTypeAll);
 
  void RemoveGCPrologueCallback(GCCallbackWithData, void* data = nullptr);
  void RemoveGCPrologueCallback(GCCallback callback);
 
  void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
 
  /*
   * Gets the currently active heap tracer for the isolate.
   */
  EmbedderHeapTracer* GetEmbedderHeapTracer();
 
  enum class AtomicsWaitEvent {
    kStartWait,
    kWokenUp,
    kTimedOut,
    kTerminatedExecution,
    kAPIStopped,
    kNotEqual
  };
 
  class V8_EXPORT AtomicsWaitWakeHandle {
   public:
    void Wake();
  };
 
  typedef void (*AtomicsWaitCallback)(AtomicsWaitEvent event,
                                      Local<SharedArrayBuffer> array_buffer,
                                      size_t offset_in_bytes, int64_t value,
                                      double timeout_in_ms,
                                      AtomicsWaitWakeHandle* stop_handle,
                                      void* data);
 
  void SetAtomicsWaitCallback(AtomicsWaitCallback callback, void* data);
 
  void AddGCEpilogueCallback(GCCallbackWithData callback, void* data = nullptr,
                             GCType gc_type_filter = kGCTypeAll);
  void AddGCEpilogueCallback(GCCallback callback,
                             GCType gc_type_filter = kGCTypeAll);
 
  void RemoveGCEpilogueCallback(GCCallbackWithData callback,
                                void* data = nullptr);
  void RemoveGCEpilogueCallback(GCCallback callback);
 
  typedef size_t (*GetExternallyAllocatedMemoryInBytesCallback)();
 
  void SetGetExternallyAllocatedMemoryInBytesCallback(
      GetExternallyAllocatedMemoryInBytesCallback callback);
 
  void TerminateExecution();
 
  bool IsExecutionTerminating();
 
  void CancelTerminateExecution();
 
  void RequestInterrupt(InterruptCallback callback, void* data);
 
  void RequestGarbageCollectionForTesting(GarbageCollectionType type);
 
  void SetEventLogger(LogEventCallback that);
 
  void AddBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
 
  void RemoveBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
 
  void AddCallCompletedCallback(CallCompletedCallback callback);
 
  void RemoveCallCompletedCallback(CallCompletedCallback callback);
 
  void SetPromiseHook(PromiseHook hook);
 
  void SetPromiseRejectCallback(PromiseRejectCallback callback);
 
  V8_DEPRECATE_SOON("Use PerformMicrotaskCheckpoint.")
  void RunMicrotasks() { PerformMicrotaskCheckpoint(); }
 
  void PerformMicrotaskCheckpoint();
 
  void EnqueueMicrotask(Local<Function> microtask);
 
  void EnqueueMicrotask(MicrotaskCallback callback, void* data = nullptr);
 
  void SetMicrotasksPolicy(MicrotasksPolicy policy);
 
  MicrotasksPolicy GetMicrotasksPolicy() const;
 
  V8_DEPRECATE_SOON("Use *WithData version.")
  void AddMicrotasksCompletedCallback(MicrotasksCompletedCallback callback);
  void AddMicrotasksCompletedCallback(
      MicrotasksCompletedCallbackWithData callback, void* data = nullptr);
 
  V8_DEPRECATE_SOON("Use *WithData version.")
  void RemoveMicrotasksCompletedCallback(MicrotasksCompletedCallback callback);
  void RemoveMicrotasksCompletedCallback(
      MicrotasksCompletedCallbackWithData callback, void* data = nullptr);
 
  void SetUseCounterCallback(UseCounterCallback callback);
 
  void SetCounterFunction(CounterLookupCallback);
 
  void SetCreateHistogramFunction(CreateHistogramCallback);
  void SetAddHistogramSampleFunction(AddHistogramSampleCallback);
 
  void SetAddCrashKeyCallback(AddCrashKeyCallback);
 
  bool IdleNotificationDeadline(double deadline_in_seconds);
 
  void LowMemoryNotification();
 
  int ContextDisposedNotification(bool dependant_context = true);
 
  void IsolateInForegroundNotification();
 
  void IsolateInBackgroundNotification();
 
  void EnableMemorySavingsMode();
 
  void DisableMemorySavingsMode();
 
  void SetRAILMode(RAILMode rail_mode);
 
  void IncreaseHeapLimitForDebugging();
 
  void RestoreOriginalHeapLimit();
 
  bool IsHeapLimitIncreasedForDebugging();
 
  void SetJitCodeEventHandler(JitCodeEventOptions options,
                              JitCodeEventHandler event_handler);
 
  void SetStackLimit(uintptr_t stack_limit);
 
  void GetCodeRange(void** start, size_t* length_in_bytes);
 
  // TODO(petermarshall): Remove this API.
  V8_DEPRECATED("Use entry_stubs + code_pages version.")
  UnwindState GetUnwindState();
 
  JSEntryStubs GetJSEntryStubs();
 
  static constexpr size_t kMinCodePagesBufferSize = 32;
 
  size_t CopyCodePages(size_t capacity, MemoryRange* code_pages_out);
 
  void SetFatalErrorHandler(FatalErrorCallback that);
 
  void SetOOMErrorHandler(OOMErrorCallback that);
 
  void AddNearHeapLimitCallback(NearHeapLimitCallback callback, void* data);
 
  void RemoveNearHeapLimitCallback(NearHeapLimitCallback callback,
                                   size_t heap_limit);
 
  void AutomaticallyRestoreInitialHeapLimit(double threshold_percent = 0.5);
 
  V8_DEPRECATED(
      "Use Isolate::SetModifyCodeGenerationFromStringsCallback instead. "
      "See http://crbug.com/v8/10096.")
  void SetAllowCodeGenerationFromStringsCallback(
      AllowCodeGenerationFromStringsCallback callback);
  void SetModifyCodeGenerationFromStringsCallback(
      ModifyCodeGenerationFromStringsCallback callback);
 
  void SetAllowWasmCodeGenerationCallback(
      AllowWasmCodeGenerationCallback callback);
 
  void SetWasmModuleCallback(ExtensionCallback callback);
  void SetWasmInstanceCallback(ExtensionCallback callback);
 
  void SetWasmStreamingCallback(WasmStreamingCallback callback);
 
  void SetWasmThreadsEnabledCallback(WasmThreadsEnabledCallback callback);
 
  void SetWasmLoadSourceMapCallback(WasmLoadSourceMapCallback callback);
 
  void SetWasmSimdEnabledCallback(WasmSimdEnabledCallback callback);
 
  bool IsDead();
 
  bool AddMessageListener(MessageCallback that,
                          Local<Value> data = Local<Value>());
 
  bool AddMessageListenerWithErrorLevel(MessageCallback that,
                                        int message_levels,
                                        Local<Value> data = Local<Value>());
 
  void RemoveMessageListeners(MessageCallback that);
 
  void SetFailedAccessCheckCallbackFunction(FailedAccessCheckCallback);
 
  void SetCaptureStackTraceForUncaughtExceptions(
      bool capture, int frame_limit = 10,
      StackTrace::StackTraceOptions options = StackTrace::kOverview);
 
  void VisitExternalResources(ExternalResourceVisitor* visitor);
 
  void VisitHandlesWithClassIds(PersistentHandleVisitor* visitor);
 
  void VisitWeakHandles(PersistentHandleVisitor* visitor);
 
  bool IsInUse();
 
  void SetAllowAtomicsWait(bool allow);
 
  enum class TimeZoneDetection { kSkip, kRedetect };
 
  void DateTimeConfigurationChangeNotification(
      TimeZoneDetection time_zone_detection = TimeZoneDetection::kSkip);
 
  void LocaleConfigurationChangeNotification();
 
  Isolate() = delete;
  ~Isolate() = delete;
  Isolate(const Isolate&) = delete;
  Isolate& operator=(const Isolate&) = delete;
  // Deleting operator new and delete here is allowed as ctor and dtor is also
  // deleted.
  void* operator new(size_t size) = delete;
  void* operator new[](size_t size) = delete;
  void operator delete(void*, size_t) = delete;
  void operator delete[](void*, size_t) = delete;
 
 private:
  template <class K, class V, class Traits>
  friend class PersistentValueMapBase;
 
  internal::Address* GetDataFromSnapshotOnce(size_t index);
  void ReportExternalAllocationLimitReached();
};
 
class V8_EXPORT StartupData {
 public:
  bool CanBeRehashed() const;
 
  const char* data;
  int raw_size;
};
 
 
typedef bool (*EntropySource)(unsigned char* buffer, size_t length);
 
typedef uintptr_t (*ReturnAddressLocationResolver)(
    uintptr_t return_addr_location);
 
 
class V8_EXPORT V8 {
 public:
  static void SetSnapshotDataBlob(StartupData* startup_blob);
 
  static void SetDcheckErrorHandler(DcheckErrorCallback that);
 
 
  static void SetFlagsFromString(const char* str);
  static void SetFlagsFromString(const char* str, size_t length);
 
  static void SetFlagsFromCommandLine(int* argc,
                                      char** argv,
                                      bool remove_flags);
 
  static const char* GetVersion();
 
  V8_INLINE static bool Initialize() {
    const int kBuildConfiguration =
        (internal::PointerCompressionIsEnabled() ? kPointerCompression : 0) |
        (internal::SmiValuesAre31Bits() ? k31BitSmis : 0) |
        (internal::HeapSandboxIsEnabled() ? kHeapSandbox : 0);
    return Initialize(kBuildConfiguration);
  }
 
  static void SetEntropySource(EntropySource source);
 
  static void SetReturnAddressLocationResolver(
      ReturnAddressLocationResolver return_address_resolver);
 
  static bool Dispose();
 
  static bool InitializeICU(const char* icu_data_file = nullptr);
 
  static bool InitializeICUDefaultLocation(const char* exec_path,
                                           const char* icu_data_file = nullptr);
 
  static void InitializeExternalStartupData(const char* directory_path);
  static void InitializeExternalStartupDataFromFile(const char* snapshot_blob);
 
  static void InitializePlatform(Platform* platform);
 
  static void ShutdownPlatform();
 
#if V8_OS_POSIX
 
  V8_DEPRECATE_SOON("Use TryHandleWebAssemblyTrapPosix")
  static bool TryHandleSignal(int signal_number, void* info, void* context);
#endif  // V8_OS_POSIX
 
  static bool EnableWebAssemblyTrapHandler(bool use_v8_signal_handler);
 
#if defined(V8_OS_WIN)
 
  static void SetUnhandledExceptionCallback(
      UnhandledExceptionCallback unhandled_exception_callback);
#endif
 
  static void GetSharedMemoryStatistics(SharedMemoryStatistics* statistics);
 
 private:
  V8();
 
  enum BuildConfigurationFeatures {
    kPointerCompression = 1 << 0,
    k31BitSmis = 1 << 1,
    kHeapSandbox = 1 << 2,
  };
 
  static bool Initialize(int build_config);
 
  static internal::Address* GlobalizeReference(internal::Isolate* isolate,
                                               internal::Address* handle);
  static internal::Address* GlobalizeTracedReference(internal::Isolate* isolate,
                                                     internal::Address* handle,
                                                     internal::Address* slot,
                                                     bool has_destructor);
  static void MoveGlobalReference(internal::Address** from,
                                  internal::Address** to);
  static void MoveTracedGlobalReference(internal::Address** from,
                                        internal::Address** to);
  static void CopyTracedGlobalReference(const internal::Address* const* from,
                                        internal::Address** to);
  static internal::Address* CopyGlobalReference(internal::Address* from);
  static void DisposeGlobal(internal::Address* global_handle);
  static void DisposeTracedGlobal(internal::Address* global_handle);
  static void MakeWeak(internal::Address* location, void* data,
                       WeakCallbackInfo<void>::Callback weak_callback,
                       WeakCallbackType type);
  static void MakeWeak(internal::Address** location_addr);
  static void* ClearWeak(internal::Address* location);
  static void SetFinalizationCallbackTraced(
      internal::Address* location, void* parameter,
      WeakCallbackInfo<void>::Callback callback);
  static void AnnotateStrongRetainer(internal::Address* location,
                                     const char* label);
  static Value* Eternalize(Isolate* isolate, Value* handle);
 
  template <class K, class V, class T>
  friend class PersistentValueMapBase;
 
  static void FromJustIsNothing();
  static void ToLocalEmpty();
  static void InternalFieldOutOfBounds(int index);
  template <class T>
  friend class Global;
  template <class T> friend class Local;
  template <class T>
  friend class MaybeLocal;
  template <class T>
  friend class Maybe;
  template <class T>
  friend class TracedReferenceBase;
  template <class T>
  friend class TracedGlobal;
  template <class T>
  friend class TracedReference;
  template <class T>
  friend class WeakCallbackInfo;
  template <class T> friend class Eternal;
  template <class T> friend class PersistentBase;
  template <class T, class M> friend class Persistent;
  friend class Context;
};
 
class V8_EXPORT SnapshotCreator {
 public:
  enum class FunctionCodeHandling { kClear, kKeep };
 
  SnapshotCreator(Isolate* isolate,
                  const intptr_t* external_references = nullptr,
                  StartupData* existing_blob = nullptr);
 
  SnapshotCreator(const intptr_t* external_references = nullptr,
                  StartupData* existing_blob = nullptr);
 
  ~SnapshotCreator();
 
  Isolate* GetIsolate();
 
  void SetDefaultContext(Local<Context> context,
                         SerializeInternalFieldsCallback callback =
                             SerializeInternalFieldsCallback());
 
  size_t AddContext(Local<Context> context,
                    SerializeInternalFieldsCallback callback =
                        SerializeInternalFieldsCallback());
 
  template <class T>
  V8_INLINE size_t AddData(Local<Context> context, Local<T> object);
 
  template <class T>
  V8_INLINE size_t AddData(Local<T> object);
 
  StartupData CreateBlob(FunctionCodeHandling function_code_handling);
 
  // Disallow copying and assigning.
  SnapshotCreator(const SnapshotCreator&) = delete;
  void operator=(const SnapshotCreator&) = delete;
 
 private:
  size_t AddData(Local<Context> context, internal::Address object);
  size_t AddData(internal::Address object);
 
  void* data_;
};
 
template <class T>
class Maybe {
 public:
  V8_INLINE bool IsNothing() const { return !has_value_; }
  V8_INLINE bool IsJust() const { return has_value_; }
 
  V8_INLINE T ToChecked() const { return FromJust(); }
 
  V8_INLINE void Check() const {
    if (V8_UNLIKELY(!IsJust())) V8::FromJustIsNothing();
  }
 
  V8_WARN_UNUSED_RESULT V8_INLINE bool To(T* out) const {
    if (V8_LIKELY(IsJust())) *out = value_;
    return IsJust();
  }
 
  V8_INLINE T FromJust() const {
    if (V8_UNLIKELY(!IsJust())) V8::FromJustIsNothing();
    return value_;
  }
 
  V8_INLINE T FromMaybe(const T& default_value) const {
    return has_value_ ? value_ : default_value;
  }
 
  V8_INLINE bool operator==(const Maybe& other) const {
    return (IsJust() == other.IsJust()) &&
           (!IsJust() || FromJust() == other.FromJust());
  }
 
  V8_INLINE bool operator!=(const Maybe& other) const {
    return !operator==(other);
  }
 
 private:
  Maybe() : has_value_(false) {}
  explicit Maybe(const T& t) : has_value_(true), value_(t) {}
 
  bool has_value_;
  T value_;
 
  template <class U>
  friend Maybe<U> Nothing();
  template <class U>
  friend Maybe<U> Just(const U& u);
};
 
template <class T>
inline Maybe<T> Nothing() {
  return Maybe<T>();
}
 
template <class T>
inline Maybe<T> Just(const T& t) {
  return Maybe<T>(t);
}
 
// A template specialization of Maybe<T> for the case of T = void.
template <>
class Maybe<void> {
 public:
  V8_INLINE bool IsNothing() const { return !is_valid_; }
  V8_INLINE bool IsJust() const { return is_valid_; }
 
  V8_INLINE bool operator==(const Maybe& other) const {
    return IsJust() == other.IsJust();
  }
 
  V8_INLINE bool operator!=(const Maybe& other) const {
    return !operator==(other);
  }
 
 private:
  struct JustTag {};
 
  Maybe() : is_valid_(false) {}
  explicit Maybe(JustTag) : is_valid_(true) {}
 
  bool is_valid_;
 
  template <class U>
  friend Maybe<U> Nothing();
  friend Maybe<void> JustVoid();
};
 
inline Maybe<void> JustVoid() { return Maybe<void>(Maybe<void>::JustTag()); }
 
class V8_EXPORT TryCatch {
 public:
  explicit TryCatch(Isolate* isolate);
 
  ~TryCatch();
 
  bool HasCaught() const;
 
  bool CanContinue() const;
 
  bool HasTerminated() const;
 
  Local<Value> ReThrow();
 
  Local<Value> Exception() const;
 
  V8_WARN_UNUSED_RESULT static MaybeLocal<Value> StackTrace(
      Local<Context> context, Local<Value> exception);
 
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> StackTrace(
      Local<Context> context) const;
 
  Local<v8::Message> Message() const;
 
  void Reset();
 
  void SetVerbose(bool value);
 
  bool IsVerbose() const;
 
  void SetCaptureMessage(bool value);
 
  static void* JSStackComparableAddress(TryCatch* handler) {
    if (handler == nullptr) return nullptr;
    return handler->js_stack_comparable_address_;
  }
 
  TryCatch(const TryCatch&) = delete;
  void operator=(const TryCatch&) = delete;
 
 private:
  // Declaring operator new and delete as deleted is not spec compliant.
  // Therefore declare them private instead to disable dynamic alloc
  void* operator new(size_t size);
  void* operator new[](size_t size);
  void operator delete(void*, size_t);
  void operator delete[](void*, size_t);
 
  void ResetInternal();
 
  internal::Isolate* isolate_;
  TryCatch* next_;
  void* exception_;
  void* message_obj_;
  void* js_stack_comparable_address_;
  bool is_verbose_ : 1;
  bool can_continue_ : 1;
  bool capture_message_ : 1;
  bool rethrow_ : 1;
  bool has_terminated_ : 1;
 
  friend class internal::Isolate;
};
 
 
// --- Context ---
 
 
class V8_EXPORT ExtensionConfiguration {
 public:
  ExtensionConfiguration() : name_count_(0), names_(nullptr) {}
  ExtensionConfiguration(int name_count, const char* names[])
      : name_count_(name_count), names_(names) { }
 
  const char** begin() const { return &names_[0]; }
  const char** end()  const { return &names_[name_count_]; }
 
 private:
  const int name_count_;
  const char** names_;
};
 
class V8_EXPORT Context {
 public:
  Local<Object> Global();
 
  void DetachGlobal();
 
  static Local<Context> New(
      Isolate* isolate, ExtensionConfiguration* extensions = nullptr,
      MaybeLocal<ObjectTemplate> global_template = MaybeLocal<ObjectTemplate>(),
      MaybeLocal<Value> global_object = MaybeLocal<Value>(),
      DeserializeInternalFieldsCallback internal_fields_deserializer =
          DeserializeInternalFieldsCallback(),
      MicrotaskQueue* microtask_queue = nullptr);
 
  static MaybeLocal<Context> FromSnapshot(
      Isolate* isolate, size_t context_snapshot_index,
      DeserializeInternalFieldsCallback embedder_fields_deserializer =
          DeserializeInternalFieldsCallback(),
      ExtensionConfiguration* extensions = nullptr,
      MaybeLocal<Value> global_object = MaybeLocal<Value>(),
      MicrotaskQueue* microtask_queue = nullptr);
 
  static MaybeLocal<Object> NewRemoteContext(
      Isolate* isolate, Local<ObjectTemplate> global_template,
      MaybeLocal<Value> global_object = MaybeLocal<Value>());
 
  void SetSecurityToken(Local<Value> token);
 
  void UseDefaultSecurityToken();
 
  Local<Value> GetSecurityToken();
 
  void Enter();
 
  void Exit();
 
  Isolate* GetIsolate();
 
  enum EmbedderDataFields { kDebugIdIndex = 0 };
 
  uint32_t GetNumberOfEmbedderDataFields();
 
  V8_INLINE Local<Value> GetEmbedderData(int index);
 
  Local<Object> GetExtrasBindingObject();
 
  void SetEmbedderData(int index, Local<Value> value);
 
  V8_INLINE void* GetAlignedPointerFromEmbedderData(int index);
 
  void SetAlignedPointerInEmbedderData(int index, void* value);
 
  void AllowCodeGenerationFromStrings(bool allow);
 
  bool IsCodeGenerationFromStringsAllowed();
 
  void SetErrorMessageForCodeGenerationFromStrings(Local<String> message);
 
  template <class T>
  V8_INLINE MaybeLocal<T> GetDataFromSnapshotOnce(size_t index);
 
  typedef void (*AbortScriptExecutionCallback)(Isolate* isolate,
                                               Local<Context> context);
  void SetAbortScriptExecution(AbortScriptExecutionCallback callback);
 
  Local<Value> GetContinuationPreservedEmbedderData() const;
 
  void SetContinuationPreservedEmbedderData(Local<Value> context);
 
  class Scope {
   public:
    explicit V8_INLINE Scope(Local<Context> context) : context_(context) {
      context_->Enter();
    }
    V8_INLINE ~Scope() { context_->Exit(); }
 
   private:
    Local<Context> context_;
  };
 
  class V8_EXPORT BackupIncumbentScope final {
   public:
    explicit BackupIncumbentScope(Local<Context> backup_incumbent_context);
    ~BackupIncumbentScope();
 
    uintptr_t JSStackComparableAddress() const {
      return js_stack_comparable_address_;
    }
 
   private:
    friend class internal::Isolate;
 
    Local<Context> backup_incumbent_context_;
    uintptr_t js_stack_comparable_address_ = 0;
    const BackupIncumbentScope* prev_ = nullptr;
  };
 
 private:
  friend class Value;
  friend class Script;
  friend class Object;
  friend class Function;
 
  internal::Address* GetDataFromSnapshotOnce(size_t index);
  Local<Value> SlowGetEmbedderData(int index);
  void* SlowGetAlignedPointerFromEmbedderData(int index);
};
 
 
class V8_EXPORT Unlocker {
 public:
  V8_INLINE explicit Unlocker(Isolate* isolate) { Initialize(isolate); }
 
  ~Unlocker();
 private:
  void Initialize(Isolate* isolate);
 
  internal::Isolate* isolate_;
};
 
 
class V8_EXPORT Locker {
 public:
  V8_INLINE explicit Locker(Isolate* isolate) { Initialize(isolate); }
 
  ~Locker();
 
  static bool IsLocked(Isolate* isolate);
 
  static bool IsActive();
 
  // Disallow copying and assigning.
  Locker(const Locker&) = delete;
  void operator=(const Locker&) = delete;
 
 private:
  void Initialize(Isolate* isolate);
 
  bool has_lock_;
  bool top_level_;
  internal::Isolate* isolate_;
};
 
class V8_EXPORT Unwinder {
 public:
  // TODO(petermarshall): Remove this API
  V8_DEPRECATED("Use entry_stubs + code_pages version.")
  static bool TryUnwindV8Frames(const UnwindState& unwind_state,
                                RegisterState* register_state,
                                const void* stack_base);
 
  static bool TryUnwindV8Frames(const JSEntryStubs& entry_stubs,
                                size_t code_pages_length,
                                const MemoryRange* code_pages,
                                RegisterState* register_state,
                                const void* stack_base);
 
  // TODO(petermarshall): Remove this API
  V8_DEPRECATED("Use code_pages version.")
  static bool PCIsInV8(const UnwindState& unwind_state, void* pc);
 
  static bool PCIsInV8(size_t code_pages_length, const MemoryRange* code_pages,
                       void* pc);
};
 
// --- Implementation ---
 
template <class T>
Local<T> Local<T>::New(Isolate* isolate, Local<T> that) {
  return New(isolate, that.val_);
}
 
template <class T>
Local<T> Local<T>::New(Isolate* isolate, const PersistentBase<T>& that) {
  return New(isolate, that.val_);
}
 
template <class T>
Local<T> Local<T>::New(Isolate* isolate, const TracedReferenceBase<T>& that) {
  return New(isolate, that.val_);
}
 
template <class T>
Local<T> Local<T>::New(Isolate* isolate, T* that) {
  if (that == nullptr) return Local<T>();
  T* that_ptr = that;
  internal::Address* p = reinterpret_cast<internal::Address*>(that_ptr);
  return Local<T>(reinterpret_cast<T*>(HandleScope::CreateHandle(
      reinterpret_cast<internal::Isolate*>(isolate), *p)));
}
 
 
template<class T>
template<class S>
void Eternal<T>::Set(Isolate* isolate, Local<S> handle) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  val_ = reinterpret_cast<T*>(
      V8::Eternalize(isolate, reinterpret_cast<Value*>(*handle)));
}
 
template <class T>
Local<T> Eternal<T>::Get(Isolate* isolate) const {
  // The eternal handle will never go away, so as with the roots, we don't even
  // need to open a handle.
  return Local<T>(val_);
}
 
 
template <class T>
Local<T> MaybeLocal<T>::ToLocalChecked() {
  if (V8_UNLIKELY(val_ == nullptr)) V8::ToLocalEmpty();
  return Local<T>(val_);
}
 
 
template <class T>
void* WeakCallbackInfo<T>::GetInternalField(int index) const {
#ifdef V8_ENABLE_CHECKS
  if (index < 0 || index >= kEmbedderFieldsInWeakCallback) {
    V8::InternalFieldOutOfBounds(index);
  }
#endif
  return embedder_fields_[index];
}
 
 
template <class T>
T* PersistentBase<T>::New(Isolate* isolate, T* that) {
  if (that == nullptr) return nullptr;
  internal::Address* p = reinterpret_cast<internal::Address*>(that);
  return reinterpret_cast<T*>(
      V8::GlobalizeReference(reinterpret_cast<internal::Isolate*>(isolate),
                             p));
}
 
 
template <class T, class M>
template <class S, class M2>
void Persistent<T, M>::Copy(const Persistent<S, M2>& that) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  this->Reset();
  if (that.IsEmpty()) return;
  internal::Address* p = reinterpret_cast<internal::Address*>(that.val_);
  this->val_ = reinterpret_cast<T*>(V8::CopyGlobalReference(p));
  M::Copy(that, this);
}
 
template <class T>
bool PersistentBase<T>::IsWeak() const {
  typedef internal::Internals I;
  if (this->IsEmpty()) return false;
  return I::GetNodeState(reinterpret_cast<internal::Address*>(this->val_)) ==
         I::kNodeStateIsWeakValue;
}
 
 
template <class T>
void PersistentBase<T>::Reset() {
  if (this->IsEmpty()) return;
  V8::DisposeGlobal(reinterpret_cast<internal::Address*>(this->val_));
  val_ = nullptr;
}
 
 
template <class T>
template <class S>
void PersistentBase<T>::Reset(Isolate* isolate, const Local<S>& other) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  Reset();
  if (other.IsEmpty()) return;
  this->val_ = New(isolate, other.val_);
}
 
 
template <class T>
template <class S>
void PersistentBase<T>::Reset(Isolate* isolate,
                              const PersistentBase<S>& other) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  Reset();
  if (other.IsEmpty()) return;
  this->val_ = New(isolate, other.val_);
}
 
 
template <class T>
template <typename P>
V8_INLINE void PersistentBase<T>::SetWeak(
    P* parameter, typename WeakCallbackInfo<P>::Callback callback,
    WeakCallbackType type) {
  typedef typename WeakCallbackInfo<void>::Callback Callback;
  V8::MakeWeak(reinterpret_cast<internal::Address*>(this->val_), parameter,
               reinterpret_cast<Callback>(callback), type);
}
 
template <class T>
void PersistentBase<T>::SetWeak() {
  V8::MakeWeak(reinterpret_cast<internal::Address**>(&this->val_));
}
 
template <class T>
template <typename P>
P* PersistentBase<T>::ClearWeak() {
  return reinterpret_cast<P*>(
      V8::ClearWeak(reinterpret_cast<internal::Address*>(this->val_)));
}
 
template <class T>
void PersistentBase<T>::AnnotateStrongRetainer(const char* label) {
  V8::AnnotateStrongRetainer(reinterpret_cast<internal::Address*>(this->val_),
                             label);
}
 
template <class T>
void PersistentBase<T>::SetWrapperClassId(uint16_t class_id) {
  typedef internal::Internals I;
  if (this->IsEmpty()) return;
  internal::Address* obj = reinterpret_cast<internal::Address*>(this->val_);
  uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
  *reinterpret_cast<uint16_t*>(addr) = class_id;
}
 
 
template <class T>
uint16_t PersistentBase<T>::WrapperClassId() const {
  typedef internal::Internals I;
  if (this->IsEmpty()) return 0;
  internal::Address* obj = reinterpret_cast<internal::Address*>(this->val_);
  uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
  return *reinterpret_cast<uint16_t*>(addr);
}
 
template <class T>
Global<T>::Global(Global&& other) : PersistentBase<T>(other.val_) {
  if (other.val_ != nullptr) {
    V8::MoveGlobalReference(reinterpret_cast<internal::Address**>(&other.val_),
                            reinterpret_cast<internal::Address**>(&this->val_));
    other.val_ = nullptr;
  }
}
 
template <class T>
template <class S>
Global<T>& Global<T>::operator=(Global<S>&& rhs) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  if (this != &rhs) {
    this->Reset();
    if (rhs.val_ != nullptr) {
      this->val_ = rhs.val_;
      V8::MoveGlobalReference(
          reinterpret_cast<internal::Address**>(&rhs.val_),
          reinterpret_cast<internal::Address**>(&this->val_));
      rhs.val_ = nullptr;
    }
  }
  return *this;
}
 
template <class T>
T* TracedReferenceBase<T>::New(Isolate* isolate, T* that, void* slot,
                               DestructionMode destruction_mode) {
  if (that == nullptr) return nullptr;
  internal::Address* p = reinterpret_cast<internal::Address*>(that);
  return reinterpret_cast<T*>(V8::GlobalizeTracedReference(
      reinterpret_cast<internal::Isolate*>(isolate), p,
      reinterpret_cast<internal::Address*>(slot),
      destruction_mode == kWithDestructor));
}
 
template <class T>
void TracedReferenceBase<T>::Reset() {
  if (IsEmpty()) return;
  V8::DisposeTracedGlobal(reinterpret_cast<internal::Address*>(val_));
  val_ = nullptr;
}
 
template <class T>
template <class S>
void TracedGlobal<T>::Reset(Isolate* isolate, const Local<S>& other) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  Reset();
  if (other.IsEmpty()) return;
  this->val_ = this->New(isolate, other.val_, &this->val_,
                         TracedReferenceBase<T>::kWithDestructor);
}
 
template <class T>
template <class S>
TracedGlobal<T>& TracedGlobal<T>::operator=(TracedGlobal<S>&& rhs) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  *this = std::move(rhs.template As<T>());
  return *this;
}
 
template <class T>
template <class S>
TracedGlobal<T>& TracedGlobal<T>::operator=(const TracedGlobal<S>& rhs) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  *this = rhs.template As<T>();
  return *this;
}
 
template <class T>
TracedGlobal<T>& TracedGlobal<T>::operator=(TracedGlobal&& rhs) {
  if (this != &rhs) {
      V8::MoveTracedGlobalReference(
          reinterpret_cast<internal::Address**>(&rhs.val_),
          reinterpret_cast<internal::Address**>(&this->val_));
  }
  return *this;
}
 
template <class T>
TracedGlobal<T>& TracedGlobal<T>::operator=(const TracedGlobal& rhs) {
  if (this != &rhs) {
    this->Reset();
    if (rhs.val_ != nullptr) {
      V8::CopyTracedGlobalReference(
          reinterpret_cast<const internal::Address* const*>(&rhs.val_),
          reinterpret_cast<internal::Address**>(&this->val_));
    }
  }
  return *this;
}
 
template <class T>
template <class S>
void TracedReference<T>::Reset(Isolate* isolate, const Local<S>& other) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  Reset();
  if (other.IsEmpty()) return;
  this->val_ = this->New(isolate, other.val_, &this->val_,
                         TracedReferenceBase<T>::kWithoutDestructor);
}
 
template <class T>
template <class S>
TracedReference<T>& TracedReference<T>::operator=(TracedReference<S>&& rhs) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  *this = std::move(rhs.template As<T>());
  return *this;
}
 
template <class T>
template <class S>
TracedReference<T>& TracedReference<T>::operator=(
    const TracedReference<S>& rhs) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  *this = rhs.template As<T>();
  return *this;
}
 
template <class T>
TracedReference<T>& TracedReference<T>::operator=(TracedReference&& rhs) {
  if (this != &rhs) {
    V8::MoveTracedGlobalReference(
        reinterpret_cast<internal::Address**>(&rhs.val_),
        reinterpret_cast<internal::Address**>(&this->val_));
  }
  return *this;
}
 
template <class T>
TracedReference<T>& TracedReference<T>::operator=(const TracedReference& rhs) {
  if (this != &rhs) {
    this->Reset();
    if (rhs.val_ != nullptr) {
      V8::CopyTracedGlobalReference(
          reinterpret_cast<const internal::Address* const*>(&rhs.val_),
          reinterpret_cast<internal::Address**>(&this->val_));
    }
  }
  return *this;
}
 
template <class T>
void TracedReferenceBase<T>::SetWrapperClassId(uint16_t class_id) {
  typedef internal::Internals I;
  if (IsEmpty()) return;
  internal::Address* obj = reinterpret_cast<internal::Address*>(val_);
  uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
  *reinterpret_cast<uint16_t*>(addr) = class_id;
}
 
template <class T>
uint16_t TracedReferenceBase<T>::WrapperClassId() const {
  typedef internal::Internals I;
  if (IsEmpty()) return 0;
  internal::Address* obj = reinterpret_cast<internal::Address*>(val_);
  uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
  return *reinterpret_cast<uint16_t*>(addr);
}
 
template <class T>
void TracedGlobal<T>::SetFinalizationCallback(
    void* parameter, typename WeakCallbackInfo<void>::Callback callback) {
  V8::SetFinalizationCallbackTraced(
      reinterpret_cast<internal::Address*>(this->val_), parameter, callback);
}
 
template <typename T>
ReturnValue<T>::ReturnValue(internal::Address* slot) : value_(slot) {}
 
template <typename T>
template <typename S>
void ReturnValue<T>::Set(const Global<S>& handle) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  if (V8_UNLIKELY(handle.IsEmpty())) {
    *value_ = GetDefaultValue();
  } else {
    *value_ = *reinterpret_cast<internal::Address*>(*handle);
  }
}
 
template <typename T>
template <typename S>
void ReturnValue<T>::Set(const TracedReferenceBase<S>& handle) {
  static_assert(std::is_base_of<T, S>::value, "type check");
  if (V8_UNLIKELY(handle.IsEmpty())) {
    *value_ = GetDefaultValue();
  } else {
    *value_ = *reinterpret_cast<internal::Address*>(handle.val_);
  }
}
 
template <typename T>
template <typename S>
void ReturnValue<T>::Set(const Local<S> handle) {
  static_assert(std::is_void<T>::value || std::is_base_of<T, S>::value,
                "type check");
  if (V8_UNLIKELY(handle.IsEmpty())) {
    *value_ = GetDefaultValue();
  } else {
    *value_ = *reinterpret_cast<internal::Address*>(*handle);
  }
}
 
template<typename T>
void ReturnValue<T>::Set(double i) {
  static_assert(std::is_base_of<T, Number>::value, "type check");
  Set(Number::New(GetIsolate(), i));
}
 
template<typename T>
void ReturnValue<T>::Set(int32_t i) {
  static_assert(std::is_base_of<T, Integer>::value, "type check");
  typedef internal::Internals I;
  if (V8_LIKELY(I::IsValidSmi(i))) {
    *value_ = I::IntToSmi(i);
    return;
  }
  Set(Integer::New(GetIsolate(), i));
}
 
template<typename T>
void ReturnValue<T>::Set(uint32_t i) {
  static_assert(std::is_base_of<T, Integer>::value, "type check");
  // Can't simply use INT32_MAX here for whatever reason.
  bool fits_into_int32_t = (i & (1U << 31)) == 0;
  if (V8_LIKELY(fits_into_int32_t)) {
    Set(static_cast<int32_t>(i));
    return;
  }
  Set(Integer::NewFromUnsigned(GetIsolate(), i));
}
 
template<typename T>
void ReturnValue<T>::Set(bool value) {
  static_assert(std::is_base_of<T, Boolean>::value, "type check");
  typedef internal::Internals I;
  int root_index;
  if (value) {
    root_index = I::kTrueValueRootIndex;
  } else {
    root_index = I::kFalseValueRootIndex;
  }
  *value_ = *I::GetRoot(GetIsolate(), root_index);
}
 
template<typename T>
void ReturnValue<T>::SetNull() {
  static_assert(std::is_base_of<T, Primitive>::value, "type check");
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kNullValueRootIndex);
}
 
template<typename T>
void ReturnValue<T>::SetUndefined() {
  static_assert(std::is_base_of<T, Primitive>::value, "type check");
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kUndefinedValueRootIndex);
}
 
template<typename T>
void ReturnValue<T>::SetEmptyString() {
  static_assert(std::is_base_of<T, String>::value, "type check");
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kEmptyStringRootIndex);
}
 
template <typename T>
Isolate* ReturnValue<T>::GetIsolate() const {
  // Isolate is always the pointer below the default value on the stack.
  return *reinterpret_cast<Isolate**>(&value_[-2]);
}
 
template <typename T>
Local<Value> ReturnValue<T>::Get() const {
  typedef internal::Internals I;
  if (*value_ == *I::GetRoot(GetIsolate(), I::kTheHoleValueRootIndex))
    return Local<Value>(*Undefined(GetIsolate()));
  return Local<Value>::New(GetIsolate(), reinterpret_cast<Value*>(value_));
}
 
template <typename T>
template <typename S>
void ReturnValue<T>::Set(S* whatever) {
  static_assert(sizeof(S) < 0, "incompilable to prevent inadvertent misuse");
}
 
template <typename T>
internal::Address ReturnValue<T>::GetDefaultValue() {
  // Default value is always the pointer below value_ on the stack.
  return value_[-1];
}
 
template <typename T>
FunctionCallbackInfo<T>::FunctionCallbackInfo(internal::Address* implicit_args,
                                              internal::Address* values,
                                              int length)
    : implicit_args_(implicit_args), values_(values), length_(length) {}
 
template<typename T>
Local<Value> FunctionCallbackInfo<T>::operator[](int i) const {
  // values_ points to the first argument (not the receiver).
  if (i < 0 || length_ <= i) return Local<Value>(*Undefined(GetIsolate()));
#ifdef V8_REVERSE_JSARGS
  return Local<Value>(reinterpret_cast<Value*>(values_ + i));
#else
  return Local<Value>(reinterpret_cast<Value*>(values_ - i));
#endif
}
 
 
template<typename T>
Local<Object> FunctionCallbackInfo<T>::This() const {
  // values_ points to the first argument (not the receiver).
#ifdef V8_REVERSE_JSARGS
  return Local<Object>(reinterpret_cast<Object*>(values_ - 1));
#else
  return Local<Object>(reinterpret_cast<Object*>(values_ + 1));
#endif
}
 
 
template<typename T>
Local<Object> FunctionCallbackInfo<T>::Holder() const {
  return Local<Object>(reinterpret_cast<Object*>(
      &implicit_args_[kHolderIndex]));
}
 
template <typename T>
Local<Value> FunctionCallbackInfo<T>::NewTarget() const {
  return Local<Value>(
      reinterpret_cast<Value*>(&implicit_args_[kNewTargetIndex]));
}
 
template <typename T>
Local<Value> FunctionCallbackInfo<T>::Data() const {
  return Local<Value>(reinterpret_cast<Value*>(&implicit_args_[kDataIndex]));
}
 
 
template<typename T>
Isolate* FunctionCallbackInfo<T>::GetIsolate() const {
  return *reinterpret_cast<Isolate**>(&implicit_args_[kIsolateIndex]);
}
 
 
template<typename T>
ReturnValue<T> FunctionCallbackInfo<T>::GetReturnValue() const {
  return ReturnValue<T>(&implicit_args_[kReturnValueIndex]);
}
 
 
template<typename T>
bool FunctionCallbackInfo<T>::IsConstructCall() const {
  return !NewTarget()->IsUndefined();
}
 
 
template<typename T>
int FunctionCallbackInfo<T>::Length() const {
  return length_;
}
 
ScriptOrigin::ScriptOrigin(Local<Value> resource_name,
                           Local<Integer> resource_line_offset,
                           Local<Integer> resource_column_offset,
                           Local<Boolean> resource_is_shared_cross_origin,
                           Local<Integer> script_id,
                           Local<Value> source_map_url,
                           Local<Boolean> resource_is_opaque,
                           Local<Boolean> is_wasm, Local<Boolean> is_module,
                           Local<PrimitiveArray> host_defined_options)
    : resource_name_(resource_name),
      resource_line_offset_(resource_line_offset),
      resource_column_offset_(resource_column_offset),
      options_(!resource_is_shared_cross_origin.IsEmpty() &&
                   resource_is_shared_cross_origin->IsTrue(),
               !resource_is_opaque.IsEmpty() && resource_is_opaque->IsTrue(),
               !is_wasm.IsEmpty() && is_wasm->IsTrue(),
               !is_module.IsEmpty() && is_module->IsTrue()),
      script_id_(script_id),
      source_map_url_(source_map_url),
      host_defined_options_(host_defined_options) {}
 
Local<Value> ScriptOrigin::ResourceName() const { return resource_name_; }
 
Local<PrimitiveArray> ScriptOrigin::HostDefinedOptions() const {
  return host_defined_options_;
}
 
Local<Integer> ScriptOrigin::ResourceLineOffset() const {
  return resource_line_offset_;
}
 
 
Local<Integer> ScriptOrigin::ResourceColumnOffset() const {
  return resource_column_offset_;
}
 
 
Local<Integer> ScriptOrigin::ScriptID() const { return script_id_; }
 
 
Local<Value> ScriptOrigin::SourceMapUrl() const { return source_map_url_; }
 
ScriptCompiler::Source::Source(Local<String> string, const ScriptOrigin& origin,
                               CachedData* data)
    : source_string(string),
      resource_name(origin.ResourceName()),
      resource_line_offset(origin.ResourceLineOffset()),
      resource_column_offset(origin.ResourceColumnOffset()),
      resource_options(origin.Options()),
      source_map_url(origin.SourceMapUrl()),
      host_defined_options(origin.HostDefinedOptions()),
      cached_data(data) {}
 
ScriptCompiler::Source::Source(Local<String> string,
                               CachedData* data)
    : source_string(string), cached_data(data) {}
 
 
ScriptCompiler::Source::~Source() {
  delete cached_data;
}
 
 
const ScriptCompiler::CachedData* ScriptCompiler::Source::GetCachedData()
    const {
  return cached_data;
}
 
const ScriptOriginOptions& ScriptCompiler::Source::GetResourceOptions() const {
  return resource_options;
}
 
Local<Boolean> Boolean::New(Isolate* isolate, bool value) {
  return value ? True(isolate) : False(isolate);
}
 
void Template::Set(Isolate* isolate, const char* name, Local<Data> value) {
  Set(String::NewFromUtf8(isolate, name, NewStringType::kInternalized)
          .ToLocalChecked(),
      value);
}
 
FunctionTemplate* FunctionTemplate::Cast(Data* data) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(data);
#endif
  return reinterpret_cast<FunctionTemplate*>(data);
}
 
ObjectTemplate* ObjectTemplate::Cast(Data* data) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(data);
#endif
  return reinterpret_cast<ObjectTemplate*>(data);
}
 
Signature* Signature::Cast(Data* data) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(data);
#endif
  return reinterpret_cast<Signature*>(data);
}
 
AccessorSignature* AccessorSignature::Cast(Data* data) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(data);
#endif
  return reinterpret_cast<AccessorSignature*>(data);
}
 
Local<Value> Object::GetInternalField(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<A*>(this);
  // Fast path: If the object is a plain JSObject, which is the common case, we
  // know where to find the internal fields and can return the value directly.
  auto instance_type = I::GetInstanceType(obj);
  if (instance_type == I::kJSObjectType ||
      instance_type == I::kJSApiObjectType ||
      instance_type == I::kJSSpecialApiObjectType) {
    int offset = I::kJSObjectHeaderSize + (I::kEmbedderDataSlotSize * index);
    A value = I::ReadRawField<A>(obj, offset);
#ifdef V8_COMPRESS_POINTERS
    // We read the full pointer value and then decompress it in order to avoid
    // dealing with potential endiannes issues.
    value = I::DecompressTaggedAnyField(obj, static_cast<uint32_t>(value));
#endif
    internal::Isolate* isolate =
        internal::IsolateFromNeverReadOnlySpaceObject(obj);
    A* result = HandleScope::CreateHandle(isolate, value);
    return Local<Value>(reinterpret_cast<Value*>(result));
  }
#endif
  return SlowGetInternalField(index);
}
 
 
void* Object::GetAlignedPointerFromInternalField(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<A*>(this);
  // Fast path: If the object is a plain JSObject, which is the common case, we
  // know where to find the internal fields and can return the value directly.
  auto instance_type = I::GetInstanceType(obj);
  if (V8_LIKELY(instance_type == I::kJSObjectType ||
                instance_type == I::kJSApiObjectType ||
                instance_type == I::kJSSpecialApiObjectType)) {
    int offset = I::kJSObjectHeaderSize + (I::kEmbedderDataSlotSize * index);
    internal::Isolate* isolate = I::GetIsolateForHeapSandbox(obj);
    A value = I::ReadExternalPointerField(isolate, obj, offset);
    return reinterpret_cast<void*>(value);
  }
#endif
  return SlowGetAlignedPointerFromInternalField(index);
}
 
String* String::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<String*>(value);
}
 
 
Local<String> String::Empty(Isolate* isolate) {
  typedef internal::Address S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kEmptyStringRootIndex);
  return Local<String>(reinterpret_cast<String*>(slot));
}
 
 
String::ExternalStringResource* String::GetExternalStringResource() const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
 
  ExternalStringResource* result;
  if (I::IsExternalTwoByteString(I::GetInstanceType(obj))) {
    internal::Isolate* isolate = I::GetIsolateForHeapSandbox(obj);
    A value =
        I::ReadExternalPointerField(isolate, obj, I::kStringResourceOffset);
    result = reinterpret_cast<String::ExternalStringResource*>(value);
  } else {
    result = GetExternalStringResourceSlow();
  }
#ifdef V8_ENABLE_CHECKS
  VerifyExternalStringResource(result);
#endif
  return result;
}
 
 
String::ExternalStringResourceBase* String::GetExternalStringResourceBase(
    String::Encoding* encoding_out) const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
  int type = I::GetInstanceType(obj) & I::kFullStringRepresentationMask;
  *encoding_out = static_cast<Encoding>(type & I::kStringEncodingMask);
  ExternalStringResourceBase* resource;
  if (type == I::kExternalOneByteRepresentationTag ||
      type == I::kExternalTwoByteRepresentationTag) {
    internal::Isolate* isolate = I::GetIsolateForHeapSandbox(obj);
    A value =
        I::ReadExternalPointerField(isolate, obj, I::kStringResourceOffset);
    resource = reinterpret_cast<ExternalStringResourceBase*>(value);
  } else {
    resource = GetExternalStringResourceBaseSlow(encoding_out);
  }
#ifdef V8_ENABLE_CHECKS
  VerifyExternalStringResourceBase(resource, *encoding_out);
#endif
  return resource;
}
 
 
bool Value::IsUndefined() const {
#ifdef V8_ENABLE_CHECKS
  return FullIsUndefined();
#else
  return QuickIsUndefined();
#endif
}
 
bool Value::QuickIsUndefined() const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
  if (!I::HasHeapObjectTag(obj)) return false;
  if (I::GetInstanceType(obj) != I::kOddballType) return false;
  return (I::GetOddballKind(obj) == I::kUndefinedOddballKind);
}
 
 
bool Value::IsNull() const {
#ifdef V8_ENABLE_CHECKS
  return FullIsNull();
#else
  return QuickIsNull();
#endif
}
 
bool Value::QuickIsNull() const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
  if (!I::HasHeapObjectTag(obj)) return false;
  if (I::GetInstanceType(obj) != I::kOddballType) return false;
  return (I::GetOddballKind(obj) == I::kNullOddballKind);
}
 
bool Value::IsNullOrUndefined() const {
#ifdef V8_ENABLE_CHECKS
  return FullIsNull() || FullIsUndefined();
#else
  return QuickIsNullOrUndefined();
#endif
}
 
bool Value::QuickIsNullOrUndefined() const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
  if (!I::HasHeapObjectTag(obj)) return false;
  if (I::GetInstanceType(obj) != I::kOddballType) return false;
  int kind = I::GetOddballKind(obj);
  return kind == I::kNullOddballKind || kind == I::kUndefinedOddballKind;
}
 
bool Value::IsString() const {
#ifdef V8_ENABLE_CHECKS
  return FullIsString();
#else
  return QuickIsString();
#endif
}
 
bool Value::QuickIsString() const {
  typedef internal::Address A;
  typedef internal::Internals I;
  A obj = *reinterpret_cast<const A*>(this);
  if (!I::HasHeapObjectTag(obj)) return false;
  return (I::GetInstanceType(obj) < I::kFirstNonstringType);
}
 
 
template <class T> Value* Value::Cast(T* value) {
  return static_cast<Value*>(value);
}
 
 
Boolean* Boolean::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Boolean*>(value);
}
 
 
Name* Name::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Name*>(value);
}
 
 
Symbol* Symbol::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Symbol*>(value);
}
 
 
Private* Private::Cast(Data* data) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(data);
#endif
  return reinterpret_cast<Private*>(data);
}
 
 
Number* Number::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Number*>(value);
}
 
 
Integer* Integer::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Integer*>(value);
}
 
 
Int32* Int32::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Int32*>(value);
}
 
 
Uint32* Uint32::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Uint32*>(value);
}
 
BigInt* BigInt::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<BigInt*>(value);
}
 
Date* Date::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Date*>(value);
}
 
 
StringObject* StringObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<StringObject*>(value);
}
 
 
SymbolObject* SymbolObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<SymbolObject*>(value);
}
 
 
NumberObject* NumberObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<NumberObject*>(value);
}
 
BigIntObject* BigIntObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<BigIntObject*>(value);
}
 
BooleanObject* BooleanObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<BooleanObject*>(value);
}
 
 
RegExp* RegExp::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<RegExp*>(value);
}
 
 
Object* Object::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Object*>(value);
}
 
 
Array* Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Array*>(value);
}
 
 
Map* Map::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Map*>(value);
}
 
 
Set* Set::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Set*>(value);
}
 
 
Promise* Promise::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Promise*>(value);
}
 
 
Proxy* Proxy::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Proxy*>(value);
}
 
WasmModuleObject* WasmModuleObject::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<WasmModuleObject*>(value);
}
 
Promise::Resolver* Promise::Resolver::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Promise::Resolver*>(value);
}
 
 
ArrayBuffer* ArrayBuffer::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<ArrayBuffer*>(value);
}
 
 
ArrayBufferView* ArrayBufferView::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<ArrayBufferView*>(value);
}
 
 
TypedArray* TypedArray::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<TypedArray*>(value);
}
 
 
Uint8Array* Uint8Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Uint8Array*>(value);
}
 
 
Int8Array* Int8Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Int8Array*>(value);
}
 
 
Uint16Array* Uint16Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Uint16Array*>(value);
}
 
 
Int16Array* Int16Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Int16Array*>(value);
}
 
 
Uint32Array* Uint32Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Uint32Array*>(value);
}
 
 
Int32Array* Int32Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Int32Array*>(value);
}
 
 
Float32Array* Float32Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Float32Array*>(value);
}
 
 
Float64Array* Float64Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Float64Array*>(value);
}
 
BigInt64Array* BigInt64Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<BigInt64Array*>(value);
}
 
BigUint64Array* BigUint64Array::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<BigUint64Array*>(value);
}
 
Uint8ClampedArray* Uint8ClampedArray::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Uint8ClampedArray*>(value);
}
 
 
DataView* DataView::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<DataView*>(value);
}
 
 
SharedArrayBuffer* SharedArrayBuffer::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<SharedArrayBuffer*>(value);
}
 
 
Function* Function::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Function*>(value);
}
 
 
External* External::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<External*>(value);
}
 
 
template<typename T>
Isolate* PropertyCallbackInfo<T>::GetIsolate() const {
  return *reinterpret_cast<Isolate**>(&args_[kIsolateIndex]);
}
 
 
template<typename T>
Local<Value> PropertyCallbackInfo<T>::Data() const {
  return Local<Value>(reinterpret_cast<Value*>(&args_[kDataIndex]));
}
 
 
template<typename T>
Local<Object> PropertyCallbackInfo<T>::This() const {
  return Local<Object>(reinterpret_cast<Object*>(&args_[kThisIndex]));
}
 
 
template<typename T>
Local<Object> PropertyCallbackInfo<T>::Holder() const {
  return Local<Object>(reinterpret_cast<Object*>(&args_[kHolderIndex]));
}
 
 
template<typename T>
ReturnValue<T> PropertyCallbackInfo<T>::GetReturnValue() const {
  return ReturnValue<T>(&args_[kReturnValueIndex]);
}
 
template <typename T>
bool PropertyCallbackInfo<T>::ShouldThrowOnError() const {
  typedef internal::Internals I;
  if (args_[kShouldThrowOnErrorIndex] !=
      I::IntToSmi(I::kInferShouldThrowMode)) {
    return args_[kShouldThrowOnErrorIndex] != I::IntToSmi(I::kDontThrow);
  }
  return v8::internal::ShouldThrowOnError(
      reinterpret_cast<v8::internal::Isolate*>(GetIsolate()));
}
 
Local<Primitive> Undefined(Isolate* isolate) {
  typedef internal::Address S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kUndefinedValueRootIndex);
  return Local<Primitive>(reinterpret_cast<Primitive*>(slot));
}
 
 
Local<Primitive> Null(Isolate* isolate) {
  typedef internal::Address S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kNullValueRootIndex);
  return Local<Primitive>(reinterpret_cast<Primitive*>(slot));
}
 
 
Local<Boolean> True(Isolate* isolate) {
  typedef internal::Address S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kTrueValueRootIndex);
  return Local<Boolean>(reinterpret_cast<Boolean*>(slot));
}
 
 
Local<Boolean> False(Isolate* isolate) {
  typedef internal::Address S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kFalseValueRootIndex);
  return Local<Boolean>(reinterpret_cast<Boolean*>(slot));
}
 
 
void Isolate::SetData(uint32_t slot, void* data) {
  typedef internal::Internals I;
  I::SetEmbedderData(this, slot, data);
}
 
 
void* Isolate::GetData(uint32_t slot) {
  typedef internal::Internals I;
  return I::GetEmbedderData(this, slot);
}
 
 
uint32_t Isolate::GetNumberOfDataSlots() {
  typedef internal::Internals I;
  return I::kNumIsolateDataSlots;
}
 
template <class T>
MaybeLocal<T> Isolate::GetDataFromSnapshotOnce(size_t index) {
  T* data = reinterpret_cast<T*>(GetDataFromSnapshotOnce(index));
  if (data) internal::PerformCastCheck(data);
  return Local<T>(data);
}
 
int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
    int64_t change_in_bytes) {
  typedef internal::Internals I;
  int64_t* external_memory = reinterpret_cast<int64_t*>(
      reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryOffset);
  int64_t* external_memory_limit = reinterpret_cast<int64_t*>(
      reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryLimitOffset);
  int64_t* external_memory_low_since_mc =
      reinterpret_cast<int64_t*>(reinterpret_cast<uint8_t*>(this) +
                                 I::kExternalMemoryLowSinceMarkCompactOffset);
 
  // Embedders are weird: we see both over- and underflows here. Perform the
  // addition with unsigned types to avoid undefined behavior.
  const int64_t amount =
      static_cast<int64_t>(static_cast<uint64_t>(change_in_bytes) +
                           static_cast<uint64_t>(*external_memory));
  *external_memory = amount;
 
  if (amount < *external_memory_low_since_mc) {
    *external_memory_low_since_mc = amount;
    *external_memory_limit = amount + I::kExternalAllocationSoftLimit;
  }
 
  if (change_in_bytes <= 0) return *external_memory;
 
  if (amount > *external_memory_limit) {
    ReportExternalAllocationLimitReached();
  }
  return *external_memory;
}
 
Local<Value> Context::GetEmbedderData(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Address A;
  typedef internal::Internals I;
  A ctx = *reinterpret_cast<const A*>(this);
  A embedder_data =
      I::ReadTaggedPointerField(ctx, I::kNativeContextEmbedderDataOffset);
  int value_offset =
      I::kEmbedderDataArrayHeaderSize + (I::kEmbedderDataSlotSize * index);
  A value = I::ReadRawField<A>(embedder_data, value_offset);
#ifdef V8_COMPRESS_POINTERS
  // We read the full pointer value and then decompress it in order to avoid
  // dealing with potential endiannes issues.
  value =
      I::DecompressTaggedAnyField(embedder_data, static_cast<uint32_t>(value));
#endif
  internal::Isolate* isolate = internal::IsolateFromNeverReadOnlySpaceObject(
      *reinterpret_cast<A*>(this));
  A* result = HandleScope::CreateHandle(isolate, value);
  return Local<Value>(reinterpret_cast<Value*>(result));
#else
  return SlowGetEmbedderData(index);
#endif
}
 
 
void* Context::GetAlignedPointerFromEmbedderData(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Address A;
  typedef internal::Internals I;
  A ctx = *reinterpret_cast<const A*>(this);
  A embedder_data =
      I::ReadTaggedPointerField(ctx, I::kNativeContextEmbedderDataOffset);
  int value_offset =
      I::kEmbedderDataArrayHeaderSize + (I::kEmbedderDataSlotSize * index);
  internal::Isolate* isolate = I::GetIsolateForHeapSandbox(ctx);
  return reinterpret_cast<void*>(
      I::ReadExternalPointerField(isolate, embedder_data, value_offset));
#else
  return SlowGetAlignedPointerFromEmbedderData(index);
#endif
}
 
template <class T>
MaybeLocal<T> Context::GetDataFromSnapshotOnce(size_t index) {
  T* data = reinterpret_cast<T*>(GetDataFromSnapshotOnce(index));
  if (data) internal::PerformCastCheck(data);
  return Local<T>(data);
}
 
template <class T>
size_t SnapshotCreator::AddData(Local<Context> context, Local<T> object) {
  T* object_ptr = *object;
  internal::Address* p = reinterpret_cast<internal::Address*>(object_ptr);
  return AddData(context, *p);
}
 
template <class T>
size_t SnapshotCreator::AddData(Local<T> object) {
  T* object_ptr = *object;
  internal::Address* p = reinterpret_cast<internal::Address*>(object_ptr);
  return AddData(*p);
}
 
}  // namespace v8
 
#endif  // INCLUDE_V8_H_