v8.h

// 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 V8_H_
#define V8_H_

#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

#include "v8-version.h"
#include "v8config.h"

// We reserve the V8_* prefix for macros defined in V8 public API and
// assume there are no name conflicts with the embedder's code.

#ifdef V8_OS_WIN

// Setup for Windows DLL export/import. When building the V8 DLL the
// BUILDING_V8_SHARED needs to be defined. When building a program which uses
// the V8 DLL USING_V8_SHARED needs to be defined. When either building the V8
// static library or building a program which uses the V8 static library neither
// BUILDING_V8_SHARED nor USING_V8_SHARED should be defined.
#if defined(BUILDING_V8_SHARED) && defined(USING_V8_SHARED)
#error both BUILDING_V8_SHARED and USING_V8_SHARED are set - please check the\
  build configuration to ensure that at most one of these is set
#endif

#ifdef BUILDING_V8_SHARED
# define V8_EXPORT __declspec(dllexport)
#elif USING_V8_SHARED
# define V8_EXPORT __declspec(dllimport)
#else
# define V8_EXPORT
#endif  // BUILDING_V8_SHARED

#else  // V8_OS_WIN

// Setup for Linux shared library export.
#if V8_HAS_ATTRIBUTE_VISIBILITY && defined(V8_SHARED)
# ifdef BUILDING_V8_SHARED
#  define V8_EXPORT __attribute__ ((visibility("default")))
# else
#  define V8_EXPORT
# endif
#else
# define V8_EXPORT
#endif

#endif  // V8_OS_WIN

namespace v8 {

class AccessorSignature;
class Array;
class Boolean;
class BooleanObject;
class Context;
class CpuProfiler;
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 Name;
class Number;
class NumberObject;
class Object;
class ObjectOperationDescriptor;
class ObjectTemplate;
class Platform;
class Primitive;
class Promise;
class RawOperationDescriptor;
class Script;
class Signature;
class StartupData;
class StackFrame;
class StackTrace;
class String;
class StringObject;
class Symbol;
class SymbolObject;
class Private;
class Uint32;
class Utils;
class Value;
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 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;
class Data;
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 {
class Arguments;
class Heap;
class HeapObject;
class Isolate;
class Object;
struct StreamedSource;
template<typename T> class CustomArguments;
class PropertyCallbackArguments;
class FunctionCallbackArguments;
class GlobalHandles;
}


class UniqueId {
 public:
  explicit UniqueId(intptr_t data)
      : data_(data) {}

  bool operator==(const UniqueId& other) const {
    return data_ == other.data_;
  }

  bool operator!=(const UniqueId& other) const {
    return data_ != other.data_;
  }

  bool operator<(const UniqueId& other) const {
    return data_ < other.data_;
  }

 private:
  intptr_t data_;
};

// --- Handles ---

#define TYPE_CHECK(T, S)                                       \
  while (false) {                                              \
    *(static_cast<T* volatile*>(0)) = static_cast<S*>(0);      \
  }


template <class T>
class Local {
 public:
  V8_INLINE Local() : val_(0) {}
  template <class S>
  V8_INLINE Local(Local<S> that)
      : val_(reinterpret_cast<T*>(*that)) {
    TYPE_CHECK(T, S);
  }

  V8_INLINE bool IsEmpty() const { return val_ == 0; }

  V8_INLINE void Clear() { val_ = 0; }

  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::Object** a = reinterpret_cast<internal::Object**>(this->val_);
    internal::Object** b = reinterpret_cast<internal::Object**>(that.val_);
    if (a == 0) return b == 0;
    if (b == 0) return false;
    return *a == *b;
  }

  template <class S> V8_INLINE bool operator==(
      const PersistentBase<S>& that) const {
    internal::Object** a = reinterpret_cast<internal::Object**>(this->val_);
    internal::Object** b = reinterpret_cast<internal::Object**>(that.val_);
    if (a == 0) return b == 0;
    if (b == 0) 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() {
    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);

 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 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 S>
  V8_INLINE Local(S* that)
      : val_(that) {}
  V8_INLINE static Local<T> New(Isolate* isolate, T* that);
  T* val_;
};


// Handle is an alias for Local for historical reasons.
template <class T>
using Handle = Local<T>;


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)) {
    TYPE_CHECK(T, S);
  }

  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();
  }

  // Will crash if the MaybeLocal<> is empty.
  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_;
};


// Eternal handles are set-once handles that live for the life of the isolate.
template <class T> class Eternal {
 public:
  V8_INLINE Eternal() : index_(kInitialValue) { }
  template<class S>
  V8_INLINE Eternal(Isolate* isolate, Local<S> handle) : index_(kInitialValue) {
    Set(isolate, handle);
  }
  // Can only be safely called if already set.
  V8_INLINE Local<T> Get(Isolate* isolate);
  V8_INLINE bool IsEmpty() { return index_ == kInitialValue; }
  template<class S> V8_INLINE void Set(Isolate* isolate, Local<S> handle);

 private:
  static const int kInitialValue = -1;
  int index_;
};


static const int kInternalFieldsInWeakCallback = 2;


template <typename T>
class WeakCallbackInfo {
 public:
  typedef void (*Callback)(const WeakCallbackInfo<T>& data);

  WeakCallbackInfo(Isolate* isolate, T* parameter,
                   void* internal_fields[kInternalFieldsInWeakCallback],
                   Callback* callback)
      : isolate_(isolate), parameter_(parameter), callback_(callback) {
    for (int i = 0; i < kInternalFieldsInWeakCallback; ++i) {
      internal_fields_[i] = internal_fields[i];
    }
  }

  V8_INLINE Isolate* GetIsolate() const { return isolate_; }
  V8_INLINE T* GetParameter() const { return parameter_; }
  V8_INLINE void* GetInternalField(int index) const;

  V8_INLINE V8_DEPRECATE_SOON("use indexed version",
                              void* GetInternalField1()) const {
    return internal_fields_[0];
  }
  V8_INLINE V8_DEPRECATE_SOON("use indexed version",
                              void* GetInternalField2()) const {
    return internal_fields_[1];
  }

  bool IsFirstPass() const { return callback_ != nullptr; }

  // 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* internal_fields_[kInternalFieldsInWeakCallback];
};


template <class T, class P>
class WeakCallbackData {
 public:
  typedef void (*Callback)(const WeakCallbackData<T, P>& data);

  WeakCallbackData(Isolate* isolate, P* parameter, Local<T> handle)
      : isolate_(isolate), parameter_(parameter), handle_(handle) {}

  V8_INLINE Isolate* GetIsolate() const { return isolate_; }
  V8_INLINE P* GetParameter() const { return parameter_; }
  V8_INLINE Local<T> GetValue() const { return handle_; }

 private:
  Isolate* isolate_;
  P* parameter_;
  Local<T> handle_;
};


// TODO(dcarney): delete this with WeakCallbackData
template <class T>
using PhantomCallbackData = WeakCallbackInfo<T>;


enum class WeakCallbackType { kParameter, kInternalFields };


template <class T> class PersistentBase {
 public:
  V8_INLINE void Reset();
  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const Handle<S>& other);

  template <class S>
  V8_INLINE void Reset(Isolate* isolate, const PersistentBase<S>& other);

  V8_INLINE bool IsEmpty() const { return val_ == NULL; }
  V8_INLINE void Empty() { val_ = 0; }

  template <class S>
  V8_INLINE bool operator==(const PersistentBase<S>& that) const {
    internal::Object** a = reinterpret_cast<internal::Object**>(this->val_);
    internal::Object** b = reinterpret_cast<internal::Object**>(that.val_);
    if (a == NULL) return b == NULL;
    if (b == NULL) return false;
    return *a == *b;
  }

  template <class S> V8_INLINE bool operator==(const Handle<S>& that) const {
    internal::Object** a = reinterpret_cast<internal::Object**>(this->val_);
    internal::Object** b = reinterpret_cast<internal::Object**>(that.val_);
    if (a == NULL) return b == NULL;
    if (b == NULL) 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 Handle<S>& that) const {
    return !operator==(that);
  }

  template <typename P>
  V8_INLINE V8_DEPRECATE_SOON(
      "use WeakCallbackInfo version",
      void SetWeak(P* parameter,
                   typename WeakCallbackData<T, P>::Callback callback));

  template <typename S, typename P>
  V8_INLINE V8_DEPRECATE_SOON(
      "use WeakCallbackInfo version",
      void SetWeak(P* parameter,
                   typename WeakCallbackData<S, P>::Callback callback));

  // Phantom persistents work like weak persistents, except that the pointer to
  // the object being collected is not available in the finalization callback.
  // This enables the garbage collector to collect the object and any objects
  // it references transitively in one GC cycle. At the moment you can either
  // specify a parameter for the callback or the location of two internal
  // fields in the dying object.
  template <typename P>
  V8_INLINE V8_DEPRECATE_SOON(
      "use SetWeak",
      void SetPhantom(P* parameter,
                      typename WeakCallbackInfo<P>::Callback callback,
                      int internal_field_index1 = -1,
                      int internal_field_index2 = -1));

  template <typename P>
  V8_INLINE void SetWeak(P* parameter,
                         typename WeakCallbackInfo<P>::Callback callback,
                         WeakCallbackType type);

  template<typename P>
  V8_INLINE P* ClearWeak();

  // TODO(dcarney): remove this.
  V8_INLINE void ClearWeak() { ClearWeak<void>(); }

  V8_INLINE void MarkIndependent();

  V8_INLINE void MarkPartiallyDependent();

  V8_INLINE bool IsIndependent() const;

  V8_INLINE bool IsNearDeath() const;

  V8_INLINE bool IsWeak() const;

  V8_INLINE void SetWrapperClassId(uint16_t class_id);

  V8_INLINE uint16_t WrapperClassId() const;

 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) {}
  PersistentBase(PersistentBase& other) = delete;  // NOLINT
  void operator=(PersistentBase&) = delete;
  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) {
    Uncompilable<Object>();
  }
  // TODO(dcarney): come up with a good compile error here.
  template<class O> V8_INLINE static void Uncompilable() {
    TYPE_CHECK(O, Primitive);
  }
};


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>(0) { }
  template <class S> V8_INLINE Persistent(Isolate* isolate, Handle<S> that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    TYPE_CHECK(T, S);
  }
  template <class S, class M2>
  V8_INLINE Persistent(Isolate* isolate, const Persistent<S, M2>& that)
    : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    TYPE_CHECK(T, S);
  }
  V8_INLINE Persistent(const Persistent& that) : PersistentBase<T>(0) {
    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) { // NOLINT
    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(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>&>(that);
  }

  // TODO(dcarney): this is pretty useless, fix or remove
  template <class S> V8_INLINE Persistent<S>& As() { // 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;

  template <class S> V8_INLINE Persistent(S* 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, Handle<S> that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
    TYPE_CHECK(T, S);
  }
  template <class S>
  V8_INLINE Global(Isolate* isolate, const PersistentBase<S>& that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, that.val_)) {
    TYPE_CHECK(T, S);
  }
  V8_INLINE Global(Global&& other) : PersistentBase<T>(other.val_) {
    other.val_ = nullptr;
  }
  V8_INLINE ~Global() { this->Reset(); }
  template <class S>
  V8_INLINE Global& operator=(Global<S>&& rhs) {
    TYPE_CHECK(T, S);
    if (this != &rhs) {
      this->Reset();
      this->val_ = rhs.val_;
      rhs.val_ = nullptr;
    }
    return *this;
  }
  Global Pass() { return static_cast<Global&&>(*this); }

  /*
   * For compatibility with Chromium's base::Bind (base::Passed).
   */
  typedef void MoveOnlyTypeForCPP03;

 private:
  Global(Global&) = delete;
  void operator=(Global&) = delete;
};


// UniquePersistent is an alias for Global for historical reason.
template <class T>
using UniquePersistent = Global<T>;


class V8_EXPORT HandleScope {
 public:
  HandleScope(Isolate* isolate);

  ~HandleScope();

  static int NumberOfHandles(Isolate* isolate);

  V8_INLINE Isolate* GetIsolate() const {
    return reinterpret_cast<Isolate*>(isolate_);
  }

 protected:
  V8_INLINE HandleScope() {}

  void Initialize(Isolate* isolate);

  static internal::Object** CreateHandle(internal::Isolate* isolate,
                                         internal::Object* value);

 private:
  // Uses heap_object to obtain the current Isolate.
  static internal::Object** CreateHandle(internal::HeapObject* heap_object,
                                         internal::Object* value);

  // Make it hard to create heap-allocated or illegal handle scopes by
  // disallowing certain operations.
  HandleScope(const HandleScope&);
  void operator=(const HandleScope&);
  void* operator new(size_t size);
  void operator delete(void*, size_t);

  internal::Isolate* isolate_;
  internal::Object** prev_next_;
  internal::Object** 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:
  EscapableHandleScope(Isolate* isolate);
  V8_INLINE ~EscapableHandleScope() {}

  template <class T>
  V8_INLINE Local<T> Escape(Local<T> value) {
    internal::Object** slot =
        Escape(reinterpret_cast<internal::Object**>(*value));
    return Local<T>(reinterpret_cast<T*>(slot));
  }

 private:
  internal::Object** Escape(internal::Object** escape_value);

  // Make it hard to create heap-allocated or illegal handle scopes by
  // disallowing certain operations.
  EscapableHandleScope(const EscapableHandleScope&);
  void operator=(const EscapableHandleScope&);
  void* operator new(size_t size);
  void operator delete(void*, size_t);

  internal::Object** escape_slot_;
};

class V8_EXPORT SealHandleScope {
 public:
  SealHandleScope(Isolate* isolate);
  ~SealHandleScope();

 private:
  // Make it hard to create heap-allocated or illegal handle scopes by
  // disallowing certain operations.
  SealHandleScope(const SealHandleScope&);
  void operator=(const SealHandleScope&);
  void* operator new(size_t size);
  void operator delete(void*, size_t);

  internal::Isolate* isolate_;
  int prev_level_;
  internal::Object** prev_limit_;
};


// --- Special objects ---


class V8_EXPORT Data {
 private:
  Data();
};


class ScriptOrigin {
 public:
  V8_INLINE ScriptOrigin(
      Handle<Value> resource_name,
      Handle<Integer> resource_line_offset = Handle<Integer>(),
      Handle<Integer> resource_column_offset = Handle<Integer>(),
      Handle<Boolean> resource_is_shared_cross_origin = Handle<Boolean>(),
      Handle<Integer> script_id = Handle<Integer>(),
      Handle<Boolean> resource_is_embedder_debug_script = Handle<Boolean>(),
      Handle<Value> source_map_url = Handle<Value>())
      : resource_name_(resource_name),
        resource_line_offset_(resource_line_offset),
        resource_column_offset_(resource_column_offset),
        resource_is_embedder_debug_script_(resource_is_embedder_debug_script),
        resource_is_shared_cross_origin_(resource_is_shared_cross_origin),
        script_id_(script_id),
        source_map_url_(source_map_url) {}
  V8_INLINE Handle<Value> ResourceName() const;
  V8_INLINE Handle<Integer> ResourceLineOffset() const;
  V8_INLINE Handle<Integer> ResourceColumnOffset() const;
  V8_INLINE Handle<Boolean> ResourceIsEmbedderDebugScript() const;
  V8_INLINE Handle<Boolean> ResourceIsSharedCrossOrigin() const;
  V8_INLINE Handle<Integer> ScriptID() const;
  V8_INLINE Handle<Value> SourceMapUrl() const;

 private:
  Handle<Value> resource_name_;
  Handle<Integer> resource_line_offset_;
  Handle<Integer> resource_column_offset_;
  Handle<Boolean> resource_is_embedder_debug_script_;
  Handle<Boolean> resource_is_shared_cross_origin_;
  Handle<Integer> script_id_;
  Handle<Value> source_map_url_;
};


class V8_EXPORT UnboundScript {
 public:
  Local<Script> BindToCurrentContext();

  int GetId();
  Handle<Value> GetScriptName();

  Handle<Value> GetSourceURL();
  Handle<Value> GetSourceMappingURL();

  int GetLineNumber(int code_pos);

  static const int kNoScriptId = 0;
};


class V8_EXPORT Script {
 public:
  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<Script> Compile(Handle<String> source,
                            ScriptOrigin* origin = nullptr));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, Handle<String> source,
      ScriptOrigin* origin = nullptr);

  static Local<Script> V8_DEPRECATE_SOON("Use maybe version",
                                         Compile(Handle<String> source,
                                                 Handle<String> file_name));

  V8_DEPRECATE_SOON("Use maybe version", Local<Value> Run());
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Run(Local<Context> context);

  Local<UnboundScript> GetUnboundScript();

  V8_DEPRECATED("Use GetUnboundScript()->GetId()",
                int GetId()) {
    return GetUnboundScript()->GetId();
  }
};


class V8_EXPORT ScriptCompiler {
 public:
  struct V8_EXPORT CachedData {
    enum BufferPolicy {
      BufferNotOwned,
      BufferOwned
    };

    CachedData()
        : data(NULL),
          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;

   private:
    // Prevent copying. Not implemented.
    CachedData(const CachedData&);
    CachedData& operator=(const CachedData&);
  };

  class Source {
   public:
    // Source takes ownership of CachedData.
    V8_INLINE Source(Local<String> source_string, const ScriptOrigin& origin,
           CachedData* cached_data = NULL);
    V8_INLINE Source(Local<String> source_string,
                     CachedData* cached_data = NULL);
    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;

   private:
    friend class ScriptCompiler;
    // Prevent copying. Not implemented.
    Source(const Source&);
    Source& operator=(const Source&);

    Local<String> source_string;

    // Origin information
    Handle<Value> resource_name;
    Handle<Integer> resource_line_offset;
    Handle<Integer> resource_column_offset;
    Handle<Boolean> resource_is_embedder_debug_script;
    Handle<Boolean> resource_is_shared_cross_origin;
    Handle<Value> source_map_url;

    // 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 ExternalSourceStream {
   public:
    virtual ~ExternalSourceStream() {}

    virtual size_t GetMoreData(const uint8_t** src) = 0;
  };


  class V8_EXPORT StreamedSource {
   public:
    enum Encoding { ONE_BYTE, TWO_BYTE, UTF8 };

    StreamedSource(ExternalSourceStream* source_stream, Encoding encoding);
    ~StreamedSource();

    // Ownership of the CachedData or its buffers is *not* transferred to the
    // caller. The CachedData object is alive as long as the StreamedSource
    // object is alive.
    const CachedData* GetCachedData() const;

    internal::StreamedSource* impl() const { return impl_; }

   private:
    // Prevent copying. Not implemented.
    StreamedSource(const StreamedSource&);
    StreamedSource& operator=(const StreamedSource&);

    internal::StreamedSource* impl_;
  };

  class ScriptStreamingTask {
   public:
    virtual ~ScriptStreamingTask() {}
    virtual void Run() = 0;
  };

  enum CompileOptions {
    kNoCompileOptions = 0,
    kProduceParserCache,
    kConsumeParserCache,
    kProduceCodeCache,
    kConsumeCodeCache,

    // Support the previous API for a transition period.
    kProduceDataToCache
  };

  static V8_DEPRECATE_SOON("Use maybe version",
                           Local<UnboundScript> CompileUnbound(
                               Isolate* isolate, Source* source,
                               CompileOptions options = kNoCompileOptions));
  static V8_WARN_UNUSED_RESULT MaybeLocal<UnboundScript> CompileUnboundScript(
      Isolate* isolate, Source* source,
      CompileOptions options = kNoCompileOptions);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<Script> Compile(Isolate* isolate, Source* source,
                            CompileOptions options = kNoCompileOptions));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, Source* source,
      CompileOptions options = kNoCompileOptions);

  static ScriptStreamingTask* StartStreamingScript(
      Isolate* isolate, StreamedSource* source,
      CompileOptions options = kNoCompileOptions);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<Script> Compile(Isolate* isolate, StreamedSource* source,
                            Handle<String> full_source_string,
                            const ScriptOrigin& origin));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> Compile(
      Local<Context> context, StreamedSource* source,
      Handle<String> full_source_string, const ScriptOrigin& origin);

  static uint32_t CachedDataVersionTag();

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<Script> CompileModule(Isolate* isolate, Source* source,
                                  CompileOptions options = kNoCompileOptions));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Script> CompileModule(
      Local<Context> context, Source* source,
      CompileOptions options = kNoCompileOptions);

  static V8_DEPRECATE_SOON("Use maybe version",
                           Local<Function> CompileFunctionInContext(
                               Isolate* isolate, Source* source,
                               Local<Context> context, size_t arguments_count,
                               Local<String> arguments[],
                               size_t context_extension_count,
                               Local<Object> context_extensions[]));
  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[]);

 private:
  static V8_WARN_UNUSED_RESULT MaybeLocal<UnboundScript> CompileUnboundInternal(
      Isolate* isolate, Source* source, CompileOptions options, bool is_module);
};


class V8_EXPORT Message {
 public:
  Local<String> Get() const;

  V8_DEPRECATE_SOON("Use maybe version", Local<String> GetSourceLine()) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<String> GetSourceLine(
      Local<Context> context) const;

  ScriptOrigin GetScriptOrigin() const;

  Handle<Value> GetScriptResourceName() const;

  Handle<StackTrace> GetStackTrace() const;

  V8_DEPRECATE_SOON("Use maybe version", int GetLineNumber()) const;
  V8_WARN_UNUSED_RESULT Maybe<int> GetLineNumber(Local<Context> context) const;

  int GetStartPosition() const;

  int GetEndPosition() const;

  V8_DEPRECATE_SOON("Use maybe version", int GetStartColumn()) const;
  V8_WARN_UNUSED_RESULT Maybe<int> GetStartColumn(Local<Context> context) const;

  V8_DEPRECATE_SOON("Use maybe version", int GetEndColumn()) const;
  V8_WARN_UNUSED_RESULT Maybe<int> GetEndColumn(Local<Context> context) const;

  bool IsSharedCrossOrigin() 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;
};


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(uint32_t index) const;

  int GetFrameCount() const;

  Local<Array> AsArray();

  static Local<StackTrace> CurrentStackTrace(
      Isolate* isolate,
      int frame_limit,
      StackTraceOptions options = kOverview);
};


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;
};


// A StateTag represents a possible state of the VM.
enum StateTag { JS, GC, COMPILER, OTHER, EXTERNAL, IDLE };


// A RegisterState represents the current state of registers used
// by the sampling profiler API.
struct RegisterState {
  RegisterState() : pc(NULL), sp(NULL), fp(NULL) {}
  void* pc;  // Instruction pointer.
  void* sp;  // Stack pointer.
  void* fp;  // Frame pointer.
};


// The output structure filled up by GetStackSample API function.
struct SampleInfo {
  size_t frames_count;
  StateTag vm_state;
};


class V8_EXPORT JSON {
 public:
  static V8_DEPRECATE_SOON("Use maybe version",
                           Local<Value> Parse(Local<String> json_string));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Value> Parse(
      Isolate* isolate, Local<String> json_string);
};


class V8_EXPORT NativeWeakMap : public Data {
 public:
  static Local<NativeWeakMap> New(Isolate* isolate);
  void Set(Handle<Value> key, Handle<Value> value);
  Local<Value> Get(Handle<Value> key);
  bool Has(Handle<Value> key);
  bool Delete(Handle<Value> key);
};


// --- Value ---


class V8_EXPORT Value : public Data {
 public:
  V8_INLINE bool IsUndefined() const;

  V8_INLINE bool IsNull() 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 IsBoolean() const;

  bool IsNumber() const;

  bool IsExternal() const;

  bool IsInt32() const;

  bool IsUint32() const;

  bool IsDate() const;

  bool IsArgumentsObject() const;

  bool IsBooleanObject() const;

  bool IsNumberObject() const;

  bool IsStringObject() const;

  bool IsSymbolObject() const;

  bool IsNativeError() const;

  bool IsRegExp() 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 IsDataView() const;

  V8_WARN_UNUSED_RESULT MaybeLocal<Boolean> ToBoolean(
      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;

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Boolean> ToBoolean(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Number> ToNumber(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<String> ToString(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<String> ToDetailString(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Object> ToObject(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Integer> ToInteger(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Uint32> ToUint32(Isolate* isolate)) const;
  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Int32> ToInt32(Isolate* isolate)) const;

  inline V8_DEPRECATE_SOON("Use maybe version",
                           Local<Boolean> ToBoolean()) const;
  inline V8_DEPRECATE_SOON("Use maybe version", Local<Number> ToNumber()) const;
  inline V8_DEPRECATE_SOON("Use maybe version", Local<String> ToString()) const;
  inline V8_DEPRECATE_SOON("Use maybe version",
                           Local<String> ToDetailString()) const;
  inline V8_DEPRECATE_SOON("Use maybe version", Local<Object> ToObject()) const;
  inline V8_DEPRECATE_SOON("Use maybe version",
                           Local<Integer> ToInteger()) const;
  inline V8_DEPRECATE_SOON("Use maybe version", Local<Uint32> ToUint32()) const;
  inline V8_DEPRECATE_SOON("Use maybe version", Local<Int32> ToInt32()) const;

  V8_DEPRECATE_SOON("Use maybe version", Local<Uint32> ToArrayIndex()) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Uint32> ToArrayIndex(
      Local<Context> context) const;

  V8_WARN_UNUSED_RESULT Maybe<bool> BooleanValue(Local<Context> context) 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_DEPRECATE_SOON("Use maybe version", bool BooleanValue()) const;
  V8_DEPRECATE_SOON("Use maybe version", double NumberValue()) const;
  V8_DEPRECATE_SOON("Use maybe version", int64_t IntegerValue()) const;
  V8_DEPRECATE_SOON("Use maybe version", uint32_t Uint32Value()) const;
  V8_DEPRECATE_SOON("Use maybe version", int32_t Int32Value()) const;

  V8_DEPRECATE_SOON("Use maybe version", bool Equals(Handle<Value> that)) const;
  V8_WARN_UNUSED_RESULT Maybe<bool> Equals(Local<Context> context,
                                           Handle<Value> that) const;
  bool StrictEquals(Handle<Value> that) const;
  bool SameValue(Handle<Value> that) const;

  template <class T> V8_INLINE static Value* Cast(T* value);

 private:
  V8_INLINE bool QuickIsUndefined() const;
  V8_INLINE bool QuickIsNull() 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 Handle<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(v8::Value* obj);
 private:
  static void CheckCast(v8::Value* obj);
};


enum class NewStringType { kNormal, kInternalized };


class V8_EXPORT String : public Name {
 public:
  static const int kMaxLength = (1 << 28) - 16;

  enum Encoding {
    UNKNOWN_ENCODING = 0x1,
    TWO_BYTE_ENCODING = 0x0,
    ONE_BYTE_ENCODING = 0x4
  };
  int Length() const;

  int Utf8Length() 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(uint16_t* buffer,
            int start = 0,
            int length = -1,
            int options = NO_OPTIONS) const;
  // One byte characters.
  int WriteOneByte(uint8_t* buffer,
                   int start = 0,
                   int length = -1,
                   int options = NO_OPTIONS) const;
  // UTF-8 encoded characters.
  int WriteUtf8(char* buffer,
                int length = -1,
                int* nchars_ref = NULL,
                int options = NO_OPTIONS) const;

  V8_INLINE static v8::Local<v8::String> Empty(Isolate* isolate);

  bool IsExternal() const;

  bool IsExternalOneByte() const;

  class V8_EXPORT ExternalStringResourceBase {  // NOLINT
   public:
    virtual ~ExternalStringResourceBase() {}

   protected:
    ExternalStringResourceBase() {}

    virtual void Dispose() { delete this; }

   private:
    // Disallow copying and assigning.
    ExternalStringResourceBase(const ExternalStringResourceBase&);
    void operator=(const ExternalStringResourceBase&);

    friend class v8::internal::Heap;
  };

  class V8_EXPORT ExternalStringResource
      : public ExternalStringResourceBase {
   public:
    virtual ~ExternalStringResource() {}

    virtual const uint16_t* data() const = 0;

    virtual size_t length() const = 0;

   protected:
    ExternalStringResource() {}
  };

  class V8_EXPORT ExternalOneByteStringResource
      : public ExternalStringResourceBase {
   public:
    virtual ~ExternalOneByteStringResource() {}
    virtual const char* data() const = 0;
    virtual size_t length() const = 0;
   protected:
    ExternalOneByteStringResource() {}
  };

  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);

  // TODO(dcarney): remove with deprecation of New functions.
  enum NewStringType {
    kNormalString = static_cast<int>(v8::NewStringType::kNormal),
    kInternalizedString = static_cast<int>(v8::NewStringType::kInternalized)
  };

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<String> NewFromUtf8(Isolate* isolate, const char* data,
                                NewStringType type = kNormalString,
                                int length = -1));

  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromUtf8(
      Isolate* isolate, const char* data, v8::NewStringType type,
      int length = -1);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<String> NewFromOneByte(Isolate* isolate, const uint8_t* data,
                                   NewStringType type = kNormalString,
                                   int length = -1));

  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromOneByte(
      Isolate* isolate, const uint8_t* data, v8::NewStringType type,
      int length = -1);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<String> NewFromTwoByte(Isolate* isolate, const uint16_t* data,
                                   NewStringType type = kNormalString,
                                   int length = -1));

  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromTwoByte(
      Isolate* isolate, const uint16_t* data, v8::NewStringType type,
      int length = -1);

  static Local<String> Concat(Handle<String> left, Handle<String> right);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<String> NewExternal(Isolate* isolate,
                                ExternalStringResource* resource));
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalTwoByte(
      Isolate* isolate, ExternalStringResource* resource);

  bool MakeExternal(ExternalStringResource* resource);

  static V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<String> NewExternal(Isolate* isolate,
                                ExternalOneByteStringResource* resource));
  static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalOneByte(
      Isolate* isolate, ExternalOneByteStringResource* resource);

  bool MakeExternal(ExternalOneByteStringResource* resource);

  bool CanMakeExternal();

  class V8_EXPORT Utf8Value {
   public:
    explicit Utf8Value(Handle<v8::Value> obj);
    ~Utf8Value();
    char* operator*() { return str_; }
    const char* operator*() const { return str_; }
    int length() const { return length_; }
   private:
    char* str_;
    int length_;

    // Disallow copying and assigning.
    Utf8Value(const Utf8Value&);
    void operator=(const Utf8Value&);
  };

  class V8_EXPORT Value {
   public:
    explicit Value(Handle<v8::Value> obj);
    ~Value();
    uint16_t* operator*() { return str_; }
    const uint16_t* operator*() const { return str_; }
    int length() const { return length_; }
   private:
    uint16_t* str_;
    int length_;

    // Disallow copying and assigning.
    Value(const Value&);
    void operator=(const Value&);
  };

 private:
  void VerifyExternalStringResourceBase(ExternalStringResourceBase* v,
                                        Encoding encoding) const;
  void VerifyExternalStringResource(ExternalStringResource* val) const;
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT Symbol : public Name {
 public:
  // Returns the print name string of the symbol, or undefined if none.
  Local<Value> Name() const;

  // Create a symbol. If name is not empty, it will be used as the description.
  static Local<Symbol> New(
      Isolate *isolate, Local<String> name = Local<String>());

  // Access global symbol registry.
  // Note that symbols created this way are never collected, so
  // they should only be used for statically fixed properties.
  // Also, there is only one global name space for the names used as keys.
  // To minimize the potential for clashes, use qualified names as keys.
  static Local<Symbol> For(Isolate *isolate, Local<String> name);

  // Retrieve a global symbol. Similar to |For|, but using a separate
  // registry that is not accessible by (and cannot clash with) JavaScript code.
  static Local<Symbol> ForApi(Isolate *isolate, Local<String> name);

  // Well-known symbols
  static Local<Symbol> GetIterator(Isolate* isolate);
  static Local<Symbol> GetUnscopables(Isolate* isolate);
  static Local<Symbol> GetToStringTag(Isolate* isolate);

  V8_INLINE static Symbol* Cast(v8::Value* obj);

 private:
  Symbol();
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT Private : public Data {
 public:
  // Returns the print name string of the private symbol, or undefined if none.
  Local<Value> Name() const;

  // Create a private symbol. If name is not empty, it will be the description.
  static Local<Private> New(
      Isolate *isolate, Local<String> name = Local<String>());

  // Retrieve a global private symbol. If a symbol with this name has not
  // been retrieved in the same isolate before, it is created.
  // Note that private symbols created this way are never collected, so
  // they should only be used for statically fixed properties.
  // Also, there is only one global name space for the names used as keys.
  // To minimize the potential for clashes, use qualified names as keys,
  // e.g., "Class#property".
  static Local<Private> ForApi(Isolate *isolate, Local<String> name);

 private:
  Private();
};


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);
};


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
};


class V8_EXPORT Object : public Value {
 public:
  V8_DEPRECATE_SOON("Use maybe version",
                    bool Set(Handle<Value> key, Handle<Value> value));
  V8_WARN_UNUSED_RESULT Maybe<bool> Set(Local<Context> context,
                                        Local<Value> key, Local<Value> value);

  V8_DEPRECATE_SOON("Use maybe version",
                    bool Set(uint32_t index, Handle<Value> value));
  V8_WARN_UNUSED_RESULT Maybe<bool> Set(Local<Context> context, uint32_t index,
                                        Local<Value> value);

  // Sets an own property on this object bypassing interceptors and
  // overriding accessors or read-only properties.
  //
  // Note that if the object has an interceptor the property will be set
  // locally, but since the interceptor takes precedence the local property
  // will only be returned if the interceptor doesn't return a value.
  //
  // Note also that this only works for named properties.
  V8_DEPRECATE_SOON("Use maybe version",
                    bool ForceSet(Handle<Value> key, Handle<Value> value,
                                  PropertyAttribute attribs = None));
  // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
  Maybe<bool> ForceSet(Local<Context> context, Local<Value> key,
                       Local<Value> value, PropertyAttribute attribs = None);

  V8_DEPRECATE_SOON("Use maybe version", Local<Value> Get(Handle<Value> key));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
                                              Local<Value> key);

  V8_DEPRECATE_SOON("Use maybe version", Local<Value> Get(uint32_t index));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
                                              uint32_t index);

  V8_DEPRECATE_SOON("Use maybe version",
                    PropertyAttribute GetPropertyAttributes(Handle<Value> key));
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute> GetPropertyAttributes(
      Local<Context> context, Local<Value> key);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Value> GetOwnPropertyDescriptor(Local<String> key));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetOwnPropertyDescriptor(
      Local<Context> context, Local<String> key);

  V8_DEPRECATE_SOON("Use maybe version", bool Has(Handle<Value> key));
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context,
                                        Local<Value> key);

  V8_DEPRECATE_SOON("Use maybe version", bool Delete(Handle<Value> key));
  // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
  Maybe<bool> Delete(Local<Context> context, Local<Value> key);

  V8_DEPRECATE_SOON("Use maybe version", bool Has(uint32_t index));
  V8_WARN_UNUSED_RESULT Maybe<bool> Has(Local<Context> context, uint32_t index);

  V8_DEPRECATE_SOON("Use maybe version", bool Delete(uint32_t index));
  // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
  Maybe<bool> Delete(Local<Context> context, uint32_t index);

  V8_DEPRECATE_SOON("Use maybe version",
                    bool SetAccessor(Handle<String> name,
                                     AccessorGetterCallback getter,
                                     AccessorSetterCallback setter = 0,
                                     Handle<Value> data = Handle<Value>(),
                                     AccessControl settings = DEFAULT,
                                     PropertyAttribute attribute = None));
  V8_DEPRECATE_SOON("Use maybe version",
                    bool SetAccessor(Handle<Name> name,
                                     AccessorNameGetterCallback getter,
                                     AccessorNameSetterCallback setter = 0,
                                     Handle<Value> data = Handle<Value>(),
                                     AccessControl settings = DEFAULT,
                                     PropertyAttribute attribute = None));
  // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
  Maybe<bool> SetAccessor(Local<Context> context, Local<Name> name,
                          AccessorNameGetterCallback getter,
                          AccessorNameSetterCallback setter = 0,
                          MaybeLocal<Value> data = MaybeLocal<Value>(),
                          AccessControl settings = DEFAULT,
                          PropertyAttribute attribute = None);

  void SetAccessorProperty(Local<Name> name,
                           Local<Function> getter,
                           Handle<Function> setter = Handle<Function>(),
                           PropertyAttribute attribute = None,
                           AccessControl settings = DEFAULT);

  // TODO(dcarney): convert these or remove?
  bool HasPrivate(Handle<Private> key);
  bool SetPrivate(Handle<Private> key, Handle<Value> value);
  bool DeletePrivate(Handle<Private> key);
  Local<Value> GetPrivate(Handle<Private> key);

  V8_DEPRECATE_SOON("Use maybe version", Local<Array> GetPropertyNames());
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetPropertyNames(
      Local<Context> context);

  V8_DEPRECATE_SOON("Use maybe version", Local<Array> GetOwnPropertyNames());
  V8_WARN_UNUSED_RESULT MaybeLocal<Array> GetOwnPropertyNames(
      Local<Context> context);

  Local<Value> GetPrototype();

  V8_DEPRECATE_SOON("Use maybe version",
                    bool SetPrototype(Handle<Value> prototype));
  V8_WARN_UNUSED_RESULT Maybe<bool> SetPrototype(Local<Context> context,
                                                 Local<Value> prototype);

  Local<Object> FindInstanceInPrototypeChain(Handle<FunctionTemplate> tmpl);

  V8_DEPRECATE_SOON("Use maybe version", Local<String> ObjectProtoToString());
  V8_WARN_UNUSED_RESULT MaybeLocal<String> ObjectProtoToString(
      Local<Context> context);

  Local<String> GetConstructorName();

  int InternalFieldCount();

  V8_INLINE static int InternalFieldCount(
      const PersistentBase<Object>& object) {
    return object.val_->InternalFieldCount();
  }

  V8_INLINE Local<Value> GetInternalField(int index);

  void SetInternalField(int index, Handle<Value> value);

  V8_INLINE void* GetAlignedPointerFromInternalField(int index);

  V8_INLINE static void* GetAlignedPointerFromInternalField(
      const PersistentBase<Object>& object, int index) {
    return object.val_->GetAlignedPointerFromInternalField(index);
  }

  void SetAlignedPointerInInternalField(int index, void* value);

  // Testers for local properties.
  V8_DEPRECATE_SOON("Use maybe version",
                    bool HasOwnProperty(Handle<String> key));
  V8_WARN_UNUSED_RESULT Maybe<bool> HasOwnProperty(Local<Context> context,
                                                   Local<Name> key);
  V8_DEPRECATE_SOON("Use maybe version",
                    bool HasRealNamedProperty(Handle<String> key));
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealNamedProperty(Local<Context> context,
                                                         Local<Name> key);
  V8_DEPRECATE_SOON("Use maybe version",
                    bool HasRealIndexedProperty(uint32_t index));
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealIndexedProperty(
      Local<Context> context, uint32_t index);
  V8_DEPRECATE_SOON("Use maybe version",
                    bool HasRealNamedCallbackProperty(Handle<String> key));
  V8_WARN_UNUSED_RESULT Maybe<bool> HasRealNamedCallbackProperty(
      Local<Context> context, Local<Name> key);

  V8_DEPRECATE_SOON(
      "Use maybe version",
      Local<Value> GetRealNamedPropertyInPrototypeChain(Handle<String> key));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetRealNamedPropertyInPrototypeChain(
      Local<Context> context, Local<Name> key);

  V8_DEPRECATE_SOON(
      "Use maybe version",
      Maybe<PropertyAttribute> GetRealNamedPropertyAttributesInPrototypeChain(
          Handle<String> key));
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute>
  GetRealNamedPropertyAttributesInPrototypeChain(Local<Context> context,
                                                 Local<Name> key);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Value> GetRealNamedProperty(Handle<String> key));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> GetRealNamedProperty(
      Local<Context> context, Local<Name> key);

  V8_DEPRECATE_SOON("Use maybe version",
                    Maybe<PropertyAttribute> GetRealNamedPropertyAttributes(
                        Handle<String> key));
  V8_WARN_UNUSED_RESULT Maybe<PropertyAttribute> GetRealNamedPropertyAttributes(
      Local<Context> context, Local<Name> key);

  bool HasNamedLookupInterceptor();

  bool HasIndexedLookupInterceptor();

  V8_DEPRECATE_SOON("No alternative", void TurnOnAccessCheck());

  int GetIdentityHash();

  // TODO(dcarney): convert these to take a isolate and optionally bailout?
  bool SetHiddenValue(Handle<String> key, Handle<Value> value);
  Local<Value> GetHiddenValue(Handle<String> key);
  bool DeleteHiddenValue(Handle<String> key);

  // TODO(dcarney): take an isolate and optionally bail out?
  Local<Object> Clone();

  Local<Context> CreationContext();

  bool IsCallable();

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Value> CallAsFunction(Handle<Value> recv, int argc,
                                                Handle<Value> argv[]));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> CallAsFunction(Local<Context> context,
                                                         Handle<Value> recv,
                                                         int argc,
                                                         Handle<Value> argv[]);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Value> CallAsConstructor(int argc,
                                                   Handle<Value> argv[]));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> CallAsConstructor(
      Local<Context> context, int argc, Local<Value> argv[]);

  V8_DEPRECATE_SOON("Keep track of isolate correctly", Isolate* GetIsolate());

  static Local<Object> New(Isolate* isolate);

  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;

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Object> CloneElementAt(uint32_t index));
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> CloneElementAt(
      Local<Context> context, uint32_t index);

  static Local<Array> New(Isolate* isolate, int length = 0);

  V8_INLINE static Array* Cast(Value* obj);
 private:
  Array();
  static void CheckCast(Value* obj);
};


template<typename T>
class ReturnValue {
 public:
  template <class S> V8_INLINE ReturnValue(const ReturnValue<S>& that)
      : value_(that.value_) {
    TYPE_CHECK(T, S);
  }
  // Handle setters
  template <typename S> V8_INLINE void Set(const Persistent<S>& handle);
  template <typename S> V8_INLINE void Set(const Handle<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();

  // Pointer setter: Uncompilable to prevent inadvertent misuse.
  template <typename S>
  V8_INLINE void Set(S* whatever);

 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::Object* value) { *value_ = value; }
  V8_INLINE internal::Object* GetDefaultValue();
  V8_INLINE explicit ReturnValue(internal::Object** slot);
  internal::Object** value_;
};


template<typename T>
class FunctionCallbackInfo {
 public:
  V8_INLINE int Length() const;
  V8_INLINE Local<Value> operator[](int i) const;
  V8_INLINE Local<Function> Callee() const;
  V8_INLINE Local<Object> This() const;
  V8_INLINE Local<Object> Holder() 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 = 7;

 protected:
  friend class internal::FunctionCallbackArguments;
  friend class internal::CustomArguments<FunctionCallbackInfo>;
  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 kCalleeIndex = 5;
  static const int kContextSaveIndex = 6;

  V8_INLINE FunctionCallbackInfo(internal::Object** implicit_args,
                   internal::Object** values,
                   int length,
                   bool is_construct_call);
  internal::Object** implicit_args_;
  internal::Object** values_;
  int length_;
  int is_construct_call_;
};


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;
  // This shouldn't be public, but the arm compiler needs it.
  static const int kArgsLength = 6;

 protected:
  friend class MacroAssembler;
  friend class internal::PropertyCallbackArguments;
  friend class internal::CustomArguments<PropertyCallbackInfo>;
  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 kThisIndex = 5;

  V8_INLINE PropertyCallbackInfo(internal::Object** args) : args_(args) {}
  internal::Object** args_;
};


typedef void (*FunctionCallback)(const FunctionCallbackInfo<Value>& info);


class V8_EXPORT Function : public Object {
 public:
  static Local<Function> New(Isolate* isolate,
                             FunctionCallback callback,
                             Local<Value> data = Local<Value>(),
                             int length = 0);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Object> NewInstance(int argc,
                                              Handle<Value> argv[])) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(
      Local<Context> context, int argc, Handle<Value> argv[]) const;

  V8_DEPRECATE_SOON("Use maybe version", Local<Object> NewInstance()) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(
      Local<Context> context) const {
    return NewInstance(context, 0, nullptr);
  }

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Value> Call(Handle<Value> recv, int argc,
                                      Handle<Value> argv[]));
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> Call(Local<Context> context,
                                               Handle<Value> recv, int argc,
                                               Handle<Value> argv[]);

  void SetName(Handle<String> name);
  Handle<Value> GetName() const;

  Handle<Value> GetInferredName() const;

  Handle<Value> GetDisplayName() const;

  int GetScriptLineNumber() const;
  int GetScriptColumnNumber() const;

  bool IsBuiltin() 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);
};


class V8_EXPORT Promise : public Object {
 public:
  class V8_EXPORT Resolver : public Object {
   public:
    static V8_DEPRECATE_SOON("Use maybe version",
                             Local<Resolver> New(Isolate* isolate));
    static V8_WARN_UNUSED_RESULT MaybeLocal<Resolver> New(
        Local<Context> context);

    Local<Promise> GetPromise();

    V8_DEPRECATE_SOON("Use maybe version", void Resolve(Handle<Value> value));
    // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
    Maybe<bool> Resolve(Local<Context> context, Handle<Value> value);

    V8_DEPRECATE_SOON("Use maybe version", void Reject(Handle<Value> value));
    // TODO(dcarney): mark V8_WARN_UNUSED_RESULT
    Maybe<bool> Reject(Local<Context> context, Handle<Value> value);

    V8_INLINE static Resolver* Cast(Value* obj);

   private:
    Resolver();
    static void CheckCast(Value* obj);
  };

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Promise> Chain(Handle<Function> handler));
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Chain(Local<Context> context,
                                                  Handle<Function> handler);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Promise> Catch(Handle<Function> handler));
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Catch(Local<Context> context,
                                                  Handle<Function> handler);

  V8_DEPRECATE_SOON("Use maybe version",
                    Local<Promise> Then(Handle<Function> handler));
  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Then(Local<Context> context,
                                                 Handle<Function> handler);

  bool HasHandler();

  V8_INLINE static Promise* Cast(Value* obj);

 private:
  Promise();
  static void CheckCast(Value* obj);
};


#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 ArrayBuffer : public Object {
 public:
  class V8_EXPORT Allocator { // NOLINT
   public:
    virtual ~Allocator() {}

    virtual void* Allocate(size_t length) = 0;

    virtual void* AllocateUninitialized(size_t length) = 0;
    virtual void Free(void* data, size_t length) = 0;
  };

  class V8_EXPORT Contents { // NOLINT
   public:
    Contents() : data_(NULL), byte_length_(0) {}

    void* Data() const { return data_; }
    size_t ByteLength() const { return byte_length_; }

   private:
    void* data_;
    size_t byte_length_;

    friend class ArrayBuffer;
  };


  size_t ByteLength() const;

  static Local<ArrayBuffer> New(Isolate* isolate, size_t byte_length);

  static Local<ArrayBuffer> New(
      Isolate* isolate, void* data, size_t byte_length,
      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);

  bool IsExternal() const;

  bool IsNeuterable() const;

  void Neuter();

  Contents Externalize();

  Contents GetContents();

  V8_INLINE static ArrayBuffer* Cast(Value* obj);

  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;

 private:
  ArrayBuffer();
  static void CheckCast(Value* obj);
};


#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;

 private:
  ArrayBufferView();
  static void CheckCast(Value* obj);
};


class V8_EXPORT TypedArray : public ArrayBufferView {
 public:
  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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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(Handle<ArrayBuffer> 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 DataView : public ArrayBufferView {
 public:
  static Local<DataView> New(Handle<ArrayBuffer> 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 Date : public Object {
 public:
  static V8_DEPRECATE_SOON("Use maybe version.",
                           Local<Value> New(Isolate* isolate, double time));
  static V8_WARN_UNUSED_RESULT MaybeLocal<Value> New(Local<Context> context,
                                                     double time);

  double ValueOf() const;

  V8_INLINE static Date* Cast(v8::Value* obj);

  static void DateTimeConfigurationChangeNotification(Isolate* isolate);

 private:
  static void CheckCast(v8::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(v8::Value* obj);

 private:
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT BooleanObject : public Object {
 public:
  static Local<Value> New(bool value);

  bool ValueOf() const;

  V8_INLINE static BooleanObject* Cast(v8::Value* obj);

 private:
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT StringObject : public Object {
 public:
  static Local<Value> New(Handle<String> value);

  Local<String> ValueOf() const;

  V8_INLINE static StringObject* Cast(v8::Value* obj);

 private:
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT SymbolObject : public Object {
 public:
  static Local<Value> New(Isolate* isolate, Handle<Symbol> value);

  Local<Symbol> ValueOf() const;

  V8_INLINE static SymbolObject* Cast(v8::Value* obj);

 private:
  static void CheckCast(v8::Value* obj);
};


class V8_EXPORT RegExp : public Object {
 public:
  enum Flags {
    kNone = 0,
    kGlobal = 1,
    kIgnoreCase = 2,
    kMultiline = 4
  };

  static V8_DEPRECATE_SOON("Use maybe version",
                           Local<RegExp> New(Handle<String> pattern,
                                             Flags flags));
  static V8_WARN_UNUSED_RESULT MaybeLocal<RegExp> New(Local<Context> context,
                                                      Handle<String> pattern,
                                                      Flags flags);

  Local<String> GetSource() const;

  Flags GetFlags() const;

  V8_INLINE static RegExp* Cast(v8::Value* obj);

 private:
  static void CheckCast(v8::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);
};


// --- Templates ---


class V8_EXPORT Template : public Data {
 public:
  void Set(Handle<Name> name, Handle<Data> value,
           PropertyAttribute attributes = None);
  V8_INLINE void Set(Isolate* isolate, const char* name, Handle<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 = 0,
                             // TODO(dcarney): gcc can't handle Local below
                             Handle<Value> data = Handle<Value>(),
                             PropertyAttribute attribute = None,
                             Local<AccessorSignature> signature =
                                 Local<AccessorSignature>(),
                             AccessControl settings = DEFAULT);
  void SetNativeDataProperty(Local<Name> name,
                             AccessorNameGetterCallback getter,
                             AccessorNameSetterCallback setter = 0,
                             // TODO(dcarney): gcc can't handle Local below
                             Handle<Value> data = Handle<Value>(),
                             PropertyAttribute attribute = None,
                             Local<AccessorSignature> signature =
                                 Local<AccessorSignature>(),
                             AccessControl settings = DEFAULT);

 private:
  Template();

  friend class ObjectTemplate;
  friend class FunctionTemplate;
};


typedef void (*NamedPropertyGetterCallback)(
    Local<String> property,
    const PropertyCallbackInfo<Value>& info);


typedef void (*NamedPropertySetterCallback)(
    Local<String> property,
    Local<Value> value,
    const PropertyCallbackInfo<Value>& info);


typedef void (*NamedPropertyQueryCallback)(
    Local<String> property,
    const PropertyCallbackInfo<Integer>& info);


typedef void (*NamedPropertyDeleterCallback)(
    Local<String> property,
    const PropertyCallbackInfo<Boolean>& info);


typedef void (*NamedPropertyEnumeratorCallback)(
    const PropertyCallbackInfo<Array>& info);


// TODO(dcarney): Deprecate and remove previous typedefs, and 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 (*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);


enum AccessType {
  ACCESS_GET,
  ACCESS_SET,
  ACCESS_HAS,
  ACCESS_DELETE,
  ACCESS_KEYS
};


typedef bool (*NamedSecurityCallback)(Local<Object> host,
                                      Local<Value> key,
                                      AccessType type,
                                      Local<Value> data);


typedef bool (*IndexedSecurityCallback)(Local<Object> host,
                                        uint32_t index,
                                        AccessType type,
                                        Local<Value> data);


class V8_EXPORT FunctionTemplate : public Template {
 public:
  static Local<FunctionTemplate> New(
      Isolate* isolate,
      FunctionCallback callback = 0,
      Handle<Value> data = Handle<Value>(),
      Handle<Signature> signature = Handle<Signature>(),
      int length = 0);

  V8_DEPRECATE_SOON("Use maybe version", Local<Function> GetFunction());
  V8_WARN_UNUSED_RESULT MaybeLocal<Function> GetFunction(
      Local<Context> context);

  void SetCallHandler(FunctionCallback callback,
                      Handle<Value> data = Handle<Value>());

  void SetLength(int length);

  Local<ObjectTemplate> InstanceTemplate();

  void Inherit(Handle<FunctionTemplate> parent);

  Local<ObjectTemplate> PrototypeTemplate();

  void SetClassName(Handle<String> name);


  void SetAcceptAnyReceiver(bool value);

  void SetHiddenPrototype(bool value);

  void ReadOnlyPrototype();

  void RemovePrototype();

  bool HasInstance(Handle<Value> object);

 private:
  FunctionTemplate();
  friend class Context;
  friend class ObjectTemplate;
};


enum class PropertyHandlerFlags {
  kNone = 0,
  // See ALL_CAN_READ above.
  kAllCanRead = 1,
  // Will not call into interceptor for properties on the receiver or prototype
  // chain.  Currently only valid for named interceptors.
  kNonMasking = 1 << 1,
  // Will not call into interceptor for symbol lookup.  Only meaningful for
  // named interceptors.
  kOnlyInterceptStrings = 1 << 2,
};


struct NamedPropertyHandlerConfiguration {
  NamedPropertyHandlerConfiguration(
      GenericNamedPropertyGetterCallback getter = 0,
      GenericNamedPropertySetterCallback setter = 0,
      GenericNamedPropertyQueryCallback query = 0,
      GenericNamedPropertyDeleterCallback deleter = 0,
      GenericNamedPropertyEnumeratorCallback enumerator = 0,
      Handle<Value> data = Handle<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        data(data),
        flags(flags) {}

  GenericNamedPropertyGetterCallback getter;
  GenericNamedPropertySetterCallback setter;
  GenericNamedPropertyQueryCallback query;
  GenericNamedPropertyDeleterCallback deleter;
  GenericNamedPropertyEnumeratorCallback enumerator;
  Handle<Value> data;
  PropertyHandlerFlags flags;
};


struct IndexedPropertyHandlerConfiguration {
  IndexedPropertyHandlerConfiguration(
      IndexedPropertyGetterCallback getter = 0,
      IndexedPropertySetterCallback setter = 0,
      IndexedPropertyQueryCallback query = 0,
      IndexedPropertyDeleterCallback deleter = 0,
      IndexedPropertyEnumeratorCallback enumerator = 0,
      Handle<Value> data = Handle<Value>(),
      PropertyHandlerFlags flags = PropertyHandlerFlags::kNone)
      : getter(getter),
        setter(setter),
        query(query),
        deleter(deleter),
        enumerator(enumerator),
        data(data),
        flags(flags) {}

  IndexedPropertyGetterCallback getter;
  IndexedPropertySetterCallback setter;
  IndexedPropertyQueryCallback query;
  IndexedPropertyDeleterCallback deleter;
  IndexedPropertyEnumeratorCallback enumerator;
  Handle<Value> data;
  PropertyHandlerFlags flags;
};


class V8_EXPORT ObjectTemplate : public Template {
 public:
  static Local<ObjectTemplate> New(
      Isolate* isolate,
      Handle<FunctionTemplate> constructor = Handle<FunctionTemplate>());
  static V8_DEPRECATE_SOON("Use isolate version", Local<ObjectTemplate> New());

  V8_DEPRECATE_SOON("Use maybe version", Local<Object> NewInstance());
  V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(Local<Context> context);

  void SetAccessor(Handle<String> name,
                   AccessorGetterCallback getter,
                   AccessorSetterCallback setter = 0,
                   Handle<Value> data = Handle<Value>(),
                   AccessControl settings = DEFAULT,
                   PropertyAttribute attribute = None,
                   Handle<AccessorSignature> signature =
                       Handle<AccessorSignature>());
  void SetAccessor(Handle<Name> name,
                   AccessorNameGetterCallback getter,
                   AccessorNameSetterCallback setter = 0,
                   Handle<Value> data = Handle<Value>(),
                   AccessControl settings = DEFAULT,
                   PropertyAttribute attribute = None,
                   Handle<AccessorSignature> signature =
                       Handle<AccessorSignature>());

  // TODO(dcarney): deprecate
  void SetNamedPropertyHandler(
      NamedPropertyGetterCallback getter,
      NamedPropertySetterCallback setter = 0,
      NamedPropertyQueryCallback query = 0,
      NamedPropertyDeleterCallback deleter = 0,
      NamedPropertyEnumeratorCallback enumerator = 0,
      Handle<Value> data = Handle<Value>());
  void SetHandler(const NamedPropertyHandlerConfiguration& configuration);

  void SetHandler(const IndexedPropertyHandlerConfiguration& configuration);
  // TODO(dcarney): deprecate
  void SetIndexedPropertyHandler(
      IndexedPropertyGetterCallback getter,
      IndexedPropertySetterCallback setter = 0,
      IndexedPropertyQueryCallback query = 0,
      IndexedPropertyDeleterCallback deleter = 0,
      IndexedPropertyEnumeratorCallback enumerator = 0,
      Handle<Value> data = Handle<Value>()) {
    SetHandler(IndexedPropertyHandlerConfiguration(getter, setter, query,
                                                   deleter, enumerator, data));
  }
  void SetCallAsFunctionHandler(FunctionCallback callback,
                                Handle<Value> data = Handle<Value>());

  void MarkAsUndetectable();

  void SetAccessCheckCallbacks(NamedSecurityCallback named_handler,
                               IndexedSecurityCallback indexed_handler,
                               Handle<Value> data = Handle<Value>(),
                               bool turned_on_by_default = true);

  int InternalFieldCount();

  void SetInternalFieldCount(int value);

 private:
  ObjectTemplate();
  static Local<ObjectTemplate> New(internal::Isolate* isolate,
                                   Handle<FunctionTemplate> constructor);
  friend class FunctionTemplate;
};


class V8_EXPORT Signature : public Data {
 public:
  static Local<Signature> New(
      Isolate* isolate,
      Handle<FunctionTemplate> receiver = Handle<FunctionTemplate>());

 private:
  Signature();
};


class V8_EXPORT AccessorSignature : public Data {
 public:
  static Local<AccessorSignature> New(Isolate* isolate,
                                      Handle<FunctionTemplate> receiver =
                                          Handle<FunctionTemplate>());

 private:
  AccessorSignature();
};


class V8_EXPORT TypeSwitch : public Data {
 public:
  static Local<TypeSwitch> New(Handle<FunctionTemplate> type);
  static Local<TypeSwitch> New(int argc, Handle<FunctionTemplate> types[]);
  int match(Handle<Value> value);
 private:
  TypeSwitch();
};


// --- Extensions ---

class V8_EXPORT ExternalOneByteStringResourceImpl
    : public String::ExternalOneByteStringResource {
 public:
  ExternalOneByteStringResourceImpl() : data_(0), length_(0) {}
  ExternalOneByteStringResourceImpl(const char* data, size_t length)
      : data_(data), length_(length) {}
  const char* data() const { return data_; }
  size_t length() const { return length_; }

 private:
  const char* data_;
  size_t length_;
};

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 = 0,
            int dep_count = 0,
            const char** deps = 0,
            int source_length = -1);
  virtual ~Extension() { }
  virtual v8::Handle<v8::FunctionTemplate> GetNativeFunctionTemplate(
      v8::Isolate* isolate, v8::Handle<v8::String> name) {
    return v8::Handle<v8::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() { return dep_count_; }
  const char** dependencies() { return deps_; }
  void set_auto_enable(bool value) { auto_enable_ = value; }
  bool auto_enable() { return auto_enable_; }

 private:
  const char* name_;
  size_t source_length_;  // expected to initialize before source_
  ExternalOneByteStringResourceImpl source_;
  int dep_count_;
  const char** deps_;
  bool auto_enable_;

  // Disallow copying and assigning.
  Extension(const Extension&);
  void operator=(const Extension&);
};


void V8_EXPORT RegisterExtension(Extension* extension);


// --- Statics ---

V8_INLINE Handle<Primitive> Undefined(Isolate* isolate);
V8_INLINE Handle<Primitive> Null(Isolate* isolate);
V8_INLINE Handle<Boolean> True(Isolate* isolate);
V8_INLINE Handle<Boolean> False(Isolate* isolate);


class V8_EXPORT ResourceConstraints {
 public:
  ResourceConstraints();

  void ConfigureDefaults(uint64_t physical_memory,
                         uint64_t virtual_memory_limit);

  // Deprecated, will be removed soon.
  V8_DEPRECATED("Use two-args version instead",
                void ConfigureDefaults(uint64_t physical_memory,
                                       uint64_t virtual_memory_limit,
                                       uint32_t number_of_processors));

  int max_semi_space_size() const { return max_semi_space_size_; }
  void set_max_semi_space_size(int value) { max_semi_space_size_ = value; }
  int max_old_space_size() const { return max_old_space_size_; }
  void set_max_old_space_size(int value) { max_old_space_size_ = value; }
  int max_executable_size() const { return max_executable_size_; }
  void set_max_executable_size(int value) { max_executable_size_ = value; }
  uint32_t* stack_limit() const { return stack_limit_; }
  // Sets an address beyond which the VM's stack may not grow.
  void set_stack_limit(uint32_t* value) { stack_limit_ = value; }
  V8_DEPRECATED("Unused, will be removed", int max_available_threads() const) {
    return max_available_threads_;
  }
  // Set the number of threads available to V8, assuming at least 1.
  V8_DEPRECATED("Unused, will be removed",
                void set_max_available_threads(int value)) {
    max_available_threads_ = value;
  }
  size_t code_range_size() const { return code_range_size_; }
  void set_code_range_size(size_t value) {
    code_range_size_ = value;
  }

 private:
  int max_semi_space_size_;
  int max_old_space_size_;
  int max_executable_size_;
  uint32_t* stack_limit_;
  int max_available_threads_;
  size_t code_range_size_;
};


// --- Exceptions ---


typedef void (*FatalErrorCallback)(const char* location, const char* message);


typedef void (*MessageCallback)(Handle<Message> message, Handle<Value> error);

// --- Tracing ---

typedef void (*LogEventCallback)(const char* name, int event);

class V8_EXPORT Exception {
 public:
  static Local<Value> RangeError(Handle<String> message);
  static Local<Value> ReferenceError(Handle<String> message);
  static Local<Value> SyntaxError(Handle<String> message);
  static Local<Value> TypeError(Handle<String> message);
  static Local<Value> Error(Handle<String> message);

  static Local<Message> CreateMessage(Handle<Value> exception);

  static Local<StackTrace> GetStackTrace(Handle<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);

// --- Memory Allocation Callback ---
enum ObjectSpace {
  kObjectSpaceNewSpace = 1 << 0,
  kObjectSpaceOldSpace = 1 << 1,
  kObjectSpaceCodeSpace = 1 << 2,
  kObjectSpaceMapSpace = 1 << 3,
  kObjectSpaceLoSpace = 1 << 4,
  kObjectSpaceAll = kObjectSpaceNewSpace | kObjectSpaceOldSpace |
                    kObjectSpaceCodeSpace | kObjectSpaceMapSpace |
                    kObjectSpaceLoSpace
};

  enum AllocationAction {
    kAllocationActionAllocate = 1 << 0,
    kAllocationActionFree = 1 << 1,
    kAllocationActionAll = kAllocationActionAllocate | kAllocationActionFree
  };

typedef void (*MemoryAllocationCallback)(ObjectSpace space,
                                         AllocationAction action,
                                         int size);

// --- Leave Script Callback ---
typedef void (*CallCompletedCallback)();

// --- Promise Reject Callback ---
enum PromiseRejectEvent {
  kPromiseRejectWithNoHandler = 0,
  kPromiseHandlerAddedAfterReject = 1
};

class PromiseRejectMessage {
 public:
  PromiseRejectMessage(Handle<Promise> promise, PromiseRejectEvent event,
                       Handle<Value> value, Handle<StackTrace> stack_trace)
      : promise_(promise),
        event_(event),
        value_(value),
        stack_trace_(stack_trace) {}

  V8_INLINE Handle<Promise> GetPromise() const { return promise_; }
  V8_INLINE PromiseRejectEvent GetEvent() const { return event_; }
  V8_INLINE Handle<Value> GetValue() const { return value_; }

  // DEPRECATED. Use v8::Exception::CreateMessage(GetValue())->GetStackTrace()
  V8_INLINE Handle<StackTrace> GetStackTrace() const { return stack_trace_; }

 private:
  Handle<Promise> promise_;
  PromiseRejectEvent event_;
  Handle<Value> value_;
  Handle<StackTrace> stack_trace_;
};

typedef void (*PromiseRejectCallback)(PromiseRejectMessage message);

// --- Microtask Callback ---
typedef void (*MicrotaskCallback)(void* data);

// --- Failed Access Check Callback ---
typedef void (*FailedAccessCheckCallback)(Local<Object> target,
                                          AccessType type,
                                          Local<Value> data);

// --- AllowCodeGenerationFromStrings callbacks ---

typedef bool (*AllowCodeGenerationFromStringsCallback)(Local<Context> context);

// --- Garbage Collection Callbacks ---

enum GCType {
  kGCTypeScavenge = 1 << 0,
  kGCTypeMarkSweepCompact = 1 << 1,
  kGCTypeAll = kGCTypeScavenge | kGCTypeMarkSweepCompact
};

enum GCCallbackFlags {
  kNoGCCallbackFlags = 0,
  kGCCallbackFlagCompacted = 1 << 0,
  kGCCallbackFlagConstructRetainedObjectInfos = 1 << 1,
  kGCCallbackFlagForced = 1 << 2
};

typedef void (*GCPrologueCallback)(GCType type, GCCallbackFlags flags);
typedef void (*GCEpilogueCallback)(GCType type, GCCallbackFlags flags);

typedef void (*InterruptCallback)(Isolate* isolate, void* data);


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 used_heap_size() { return used_heap_size_; }
  size_t heap_size_limit() { return heap_size_limit_; }

 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_;

  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 RetainedObjectInfo;


typedef void (*FunctionEntryHook)(uintptr_t function,
                                  uintptr_t return_addr_location);

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 };

  // Type of event.
  EventType type;
  // Start of the instructions.
  void* code_start;
  // Size of the instructions.
  size_t code_len;
  // Script info for CODE_ADDED event.
  Handle<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 postion
    size_t pos;
    // The position type.
    PositionType position_type;
  };

  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;
  };
};

enum JitCodeEventOptions {
  kJitCodeEventDefault = 0,
  // Generate callbacks for already existent code.
  kJitCodeEventEnumExisting = 1
};


typedef void (*JitCodeEventHandler)(const JitCodeEvent* event);


class V8_EXPORT ExternalResourceVisitor {  // NOLINT
 public:
  virtual ~ExternalResourceVisitor() {}
  virtual void VisitExternalString(Handle<String> string) {}
};


class V8_EXPORT PersistentHandleVisitor {  // NOLINT
 public:
  virtual ~PersistentHandleVisitor() {}
  virtual void VisitPersistentHandle(Persistent<Value>* value,
                                     uint16_t class_id) {}
};


class V8_EXPORT Isolate {
 public:
  struct CreateParams {
    CreateParams()
        : entry_hook(NULL),
          code_event_handler(NULL),
          snapshot_blob(NULL),
          counter_lookup_callback(NULL),
          create_histogram_callback(NULL),
          add_histogram_sample_callback(NULL),
          array_buffer_allocator(NULL) {}

    FunctionEntryHook entry_hook;

    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;
  };


  class V8_EXPORT Scope {
   public:
    explicit Scope(Isolate* isolate) : isolate_(isolate) {
      isolate->Enter();
    }

    ~Scope() { isolate_->Exit(); }

   private:
    Isolate* const isolate_;

    // Prevent copying of Scope objects.
    Scope(const Scope&);
    Scope& operator=(const Scope&);
  };


  class V8_EXPORT DisallowJavascriptExecutionScope {
   public:
    enum OnFailure { CRASH_ON_FAILURE, THROW_ON_FAILURE };

    DisallowJavascriptExecutionScope(Isolate* isolate, OnFailure on_failure);
    ~DisallowJavascriptExecutionScope();

   private:
    bool on_failure_;
    void* internal_;

    // Prevent copying of Scope objects.
    DisallowJavascriptExecutionScope(const DisallowJavascriptExecutionScope&);
    DisallowJavascriptExecutionScope& operator=(
        const DisallowJavascriptExecutionScope&);
  };


  class V8_EXPORT AllowJavascriptExecutionScope {
   public:
    explicit AllowJavascriptExecutionScope(Isolate* isolate);
    ~AllowJavascriptExecutionScope();

   private:
    void* internal_throws_;
    void* internal_assert_;

    // Prevent copying of Scope objects.
    AllowJavascriptExecutionScope(const AllowJavascriptExecutionScope&);
    AllowJavascriptExecutionScope& operator=(
        const AllowJavascriptExecutionScope&);
  };

  class V8_EXPORT SuppressMicrotaskExecutionScope {
   public:
    explicit SuppressMicrotaskExecutionScope(Isolate* isolate);
    ~SuppressMicrotaskExecutionScope();

   private:
    internal::Isolate* isolate_;

    // Prevent copying of Scope objects.
    SuppressMicrotaskExecutionScope(const SuppressMicrotaskExecutionScope&);
    SuppressMicrotaskExecutionScope& operator=(
        const SuppressMicrotaskExecutionScope&);
  };

  enum GarbageCollectionType {
    kFullGarbageCollection,
    kMinorGarbageCollection
  };

  enum UseCounterFeature {
    kUseAsm = 0,
    kBreakIterator = 1,
    kLegacyConst = 2,
    kMarkDequeOverflow = 3,
    kStoreBufferOverflow = 4,
    kSlotsBufferOverflow = 5,
    kObjectObserve = 6,
    kForcedGC = 7,
    kUseCounterFeatureCount  // This enum value must be last.
  };

  typedef void (*UseCounterCallback)(Isolate* isolate,
                                     UseCounterFeature feature);


  static Isolate* New(const CreateParams& params);

  static V8_DEPRECATE_SOON("Always pass CreateParams", Isolate* New());

  static Isolate* GetCurrent();

  void Enter();

  void Exit();

  void Dispose();

  V8_INLINE void SetData(uint32_t slot, void* data);

  V8_INLINE void* GetData(uint32_t slot);

  V8_INLINE static uint32_t GetNumberOfDataSlots();

  void GetHeapStatistics(HeapStatistics* heap_statistics);

  size_t NumberOfHeapSpaces();

  bool GetHeapSpaceStatistics(HeapSpaceStatistics* space_statistics,
                              size_t index);

  void GetStackSample(const RegisterState& state, void** frames,
                      size_t frames_limit, SampleInfo* sample_info);

  V8_INLINE int64_t
      AdjustAmountOfExternalAllocatedMemory(int64_t change_in_bytes);

  HeapProfiler* GetHeapProfiler();

  CpuProfiler* GetCpuProfiler();

  bool InContext();

  Local<Context> GetCurrentContext();

  Local<Context> GetCallingContext();

  Local<Context> GetEnteredContext();

  Local<Value> ThrowException(Local<Value> exception);

  template<typename T> void SetObjectGroupId(const Persistent<T>& object,
                                             UniqueId id);

  template<typename T> void SetReferenceFromGroup(UniqueId id,
                                                  const Persistent<T>& child);

  template<typename T, typename S>
  void SetReference(const Persistent<T>& parent, const Persistent<S>& child);

  typedef void (*GCPrologueCallback)(Isolate* isolate,
                                     GCType type,
                                     GCCallbackFlags flags);
  typedef void (*GCEpilogueCallback)(Isolate* isolate,
                                     GCType type,
                                     GCCallbackFlags flags);

  void AddGCPrologueCallback(
      GCPrologueCallback callback, GCType gc_type_filter = kGCTypeAll);

  void RemoveGCPrologueCallback(GCPrologueCallback callback);

  void AddGCEpilogueCallback(
      GCEpilogueCallback callback, GCType gc_type_filter = kGCTypeAll);

  void RemoveGCEpilogueCallback(GCEpilogueCallback callback);


  void TerminateExecution();

  bool IsExecutionTerminating();

  void CancelTerminateExecution();

  void RequestInterrupt(InterruptCallback callback, void* data);

  void RequestGarbageCollectionForTesting(GarbageCollectionType type);

  void SetEventLogger(LogEventCallback that);

  void AddCallCompletedCallback(CallCompletedCallback callback);

  void RemoveCallCompletedCallback(CallCompletedCallback callback);


  void SetPromiseRejectCallback(PromiseRejectCallback callback);

  void RunMicrotasks();

  void EnqueueMicrotask(Handle<Function> microtask);

  void EnqueueMicrotask(MicrotaskCallback microtask, void* data = NULL);

  void SetAutorunMicrotasks(bool autorun);

  bool WillAutorunMicrotasks() const;

  void SetUseCounterCallback(UseCounterCallback callback);

  void SetCounterFunction(CounterLookupCallback);

  void SetCreateHistogramFunction(CreateHistogramCallback);
  void SetAddHistogramSampleFunction(AddHistogramSampleCallback);

  bool IdleNotificationDeadline(double deadline_in_seconds);

  V8_DEPRECATE_SOON("use IdleNotificationDeadline()",
                    bool IdleNotification(int idle_time_in_ms));

  void LowMemoryNotification();

  int ContextDisposedNotification(bool dependant_context = true);

  void SetJitCodeEventHandler(JitCodeEventOptions options,
                              JitCodeEventHandler event_handler);

  void SetStackLimit(uintptr_t stack_limit);

  void GetCodeRange(void** start, size_t* length_in_bytes);

  void SetFatalErrorHandler(FatalErrorCallback that);

  void SetAllowCodeGenerationFromStringsCallback(
      AllowCodeGenerationFromStringsCallback callback);

  bool IsDead();

  bool AddMessageListener(MessageCallback that,
                          Handle<Value> data = Handle<Value>());

  void RemoveMessageListeners(MessageCallback that);

  void SetFailedAccessCheckCallbackFunction(FailedAccessCheckCallback);

  void SetCaptureStackTraceForUncaughtExceptions(
      bool capture, int frame_limit = 10,
      StackTrace::StackTraceOptions options = StackTrace::kOverview);

  void AddMemoryAllocationCallback(MemoryAllocationCallback callback,
                                   ObjectSpace space, AllocationAction action);

  void RemoveMemoryAllocationCallback(MemoryAllocationCallback callback);

  void VisitExternalResources(ExternalResourceVisitor* visitor);

  void VisitHandlesWithClassIds(PersistentHandleVisitor* visitor);

  void VisitHandlesForPartialDependence(PersistentHandleVisitor* visitor);

 private:
  template <class K, class V, class Traits>
  friend class PersistentValueMapBase;

  Isolate();
  Isolate(const Isolate&);
  ~Isolate();
  Isolate& operator=(const Isolate&);
  void* operator new(size_t size);
  void operator delete(void*, size_t);

  void SetObjectGroupId(internal::Object** object, UniqueId id);
  void SetReferenceFromGroup(UniqueId id, internal::Object** object);
  void SetReference(internal::Object** parent, internal::Object** child);
  void CollectAllGarbage(const char* gc_reason);
};

class V8_EXPORT StartupData {
 public:
  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:
  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void SetFatalErrorHandler(FatalErrorCallback that));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version", void SetAllowCodeGenerationFromStringsCallback(
                                 AllowCodeGenerationFromStringsCallback that));

  static V8_DEPRECATE_SOON(
      "Use isolate version",
      void SetArrayBufferAllocator(ArrayBuffer::Allocator* allocator));

  V8_INLINE static V8_DEPRECATE_SOON("no alternative", bool IsDead());

  static void SetNativesDataBlob(StartupData* startup_blob);
  static void SetSnapshotDataBlob(StartupData* startup_blob);

  static StartupData CreateSnapshotDataBlob(const char* custom_source = NULL);

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      bool AddMessageListener(MessageCallback that,
                              Handle<Value> data = Handle<Value>()));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version", void RemoveMessageListeners(MessageCallback that));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void SetCaptureStackTraceForUncaughtExceptions(
          bool capture, int frame_limit = 10,
          StackTrace::StackTraceOptions options = StackTrace::kOverview));

  static void SetFlagsFromString(const char* str, int length);

  static void SetFlagsFromCommandLine(int* argc,
                                      char** argv,
                                      bool remove_flags);

  static const char* GetVersion();

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void SetFailedAccessCheckCallbackFunction(FailedAccessCheckCallback));

  static V8_DEPRECATE_SOON(
      "Use isolate version",
      void AddGCPrologueCallback(GCPrologueCallback callback,
                                 GCType gc_type_filter = kGCTypeAll));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void RemoveGCPrologueCallback(GCPrologueCallback callback));

  static V8_DEPRECATE_SOON(
      "Use isolate version",
      void AddGCEpilogueCallback(GCEpilogueCallback callback,
                                 GCType gc_type_filter = kGCTypeAll));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void RemoveGCEpilogueCallback(GCEpilogueCallback callback));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void AddMemoryAllocationCallback(MemoryAllocationCallback callback,
                                       ObjectSpace space,
                                       AllocationAction action));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void RemoveMemoryAllocationCallback(MemoryAllocationCallback callback));

  static bool Initialize();

  static void SetEntropySource(EntropySource source);

  static void SetReturnAddressLocationResolver(
      ReturnAddressLocationResolver return_address_resolver);

  V8_INLINE static V8_DEPRECATE_SOON("Use isolate version",
                                     void TerminateExecution(Isolate* isolate));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      bool IsExecutionTerminating(Isolate* isolate = NULL));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version", void CancelTerminateExecution(Isolate* isolate));

  static bool Dispose();

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isoalte version",
      void VisitExternalResources(ExternalResourceVisitor* visitor));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void VisitHandlesWithClassIds(PersistentHandleVisitor* visitor));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void VisitHandlesWithClassIds(Isolate* isolate,
                                    PersistentHandleVisitor* visitor));

  V8_INLINE static V8_DEPRECATE_SOON(
      "Use isolate version",
      void VisitHandlesForPartialDependence(Isolate* isolate,
                                            PersistentHandleVisitor* visitor));

  static bool InitializeICU(const char* icu_data_file = NULL);

  static void InitializePlatform(Platform* platform);

  static void ShutdownPlatform();

 private:
  V8();

  static internal::Object** GlobalizeReference(internal::Isolate* isolate,
                                               internal::Object** handle);
  static internal::Object** CopyPersistent(internal::Object** handle);
  static void DisposeGlobal(internal::Object** global_handle);
  typedef WeakCallbackData<Value, void>::Callback WeakCallback;
  static void MakeWeak(internal::Object** global_handle, void* data,
                       WeakCallback weak_callback);
  static void MakeWeak(internal::Object** global_handle, void* data,
                       WeakCallbackInfo<void>::Callback weak_callback,
                       WeakCallbackType type);
  static void MakeWeak(internal::Object** global_handle, void* data,
                       // Must be 0 or -1.
                       int internal_field_index1,
                       // Must be 1 or -1.
                       int internal_field_index2,
                       WeakCallbackInfo<void>::Callback weak_callback);
  static void* ClearWeak(internal::Object** global_handle);
  static void Eternalize(Isolate* isolate,
                         Value* handle,
                         int* index);
  static Local<Value> GetEternal(Isolate* isolate, int index);

  static void FromJustIsNothing();
  static void ToLocalEmpty();
  static void InternalFieldOutOfBounds(int index);
  template <class T> friend class Local;
  template <class T>
  friend class MaybeLocal;
  template <class T>
  friend class Maybe;
  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;
};


template <class T>
class Maybe {
 public:
  V8_INLINE bool IsNothing() const { return !has_value; }
  V8_INLINE bool IsJust() const { return has_value; }

  // Will crash if the Maybe<> is nothing.
  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);
}


class V8_EXPORT TryCatch {
 public:
  V8_DEPRECATE_SOON("Use isolate version", TryCatch());

  TryCatch(Isolate* isolate);

  ~TryCatch();

  bool HasCaught() const;

  bool CanContinue() const;

  bool HasTerminated() const;

  Handle<Value> ReThrow();

  Local<Value> Exception() const;

  V8_DEPRECATE_SOON("Use maybe version.", Local<Value> StackTrace()) const;
  V8_WARN_UNUSED_RESULT MaybeLocal<Value> StackTrace(
      Local<Context> context) const;

  Local<v8::Message> Message() const;

  void Reset();

  void SetVerbose(bool value);

  void SetCaptureMessage(bool value);

  static void* JSStackComparableAddress(v8::TryCatch* handler) {
    if (handler == NULL) return NULL;
    return handler->js_stack_comparable_address_;
  }

 private:
  void ResetInternal();

  // Make it hard to create heap-allocated TryCatch blocks.
  TryCatch(const TryCatch&);
  void operator=(const TryCatch&);
  void* operator new(size_t size);
  void operator delete(void*, size_t);

  v8::internal::Isolate* isolate_;
  v8::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 v8::internal::Isolate;
};


// --- Context ---


class V8_EXPORT ExtensionConfiguration {
 public:
  ExtensionConfiguration() : name_count_(0), names_(NULL) { }
  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 = NULL,
      Handle<ObjectTemplate> global_template = Handle<ObjectTemplate>(),
      Handle<Value> global_object = Handle<Value>());

  void SetSecurityToken(Handle<Value> token);

  void UseDefaultSecurityToken();

  Handle<Value> GetSecurityToken();

  void Enter();

  void Exit();

  v8::Isolate* GetIsolate();

  enum EmbedderDataFields { kDebugIdIndex = 0 };

  V8_INLINE Local<Value> GetEmbedderData(int index);

  void SetEmbedderData(int index, Handle<Value> value);

  V8_INLINE void* GetAlignedPointerFromEmbedderData(int index);

  void SetAlignedPointerInEmbedderData(int index, void* value);

  void AllowCodeGenerationFromStrings(bool allow);

  bool IsCodeGenerationFromStringsAllowed();

  void SetErrorMessageForCodeGenerationFromStrings(Handle<String> message);

  class Scope {
   public:
    explicit V8_INLINE Scope(Handle<Context> context) : context_(context) {
      context_->Enter();
    }
    V8_INLINE ~Scope() { context_->Exit(); }

   private:
    Handle<Context> context_;
  };

 private:
  friend class Value;
  friend class Script;
  friend class Object;
  friend class Function;

  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();

 private:
  void Initialize(Isolate* isolate);

  bool has_lock_;
  bool top_level_;
  internal::Isolate* isolate_;

  // Disallow copying and assigning.
  Locker(const Locker&);
  void operator=(const Locker&);
};


// --- Implementation ---


namespace internal {

const int kApiPointerSize = sizeof(void*);  // NOLINT
const int kApiIntSize = sizeof(int);  // NOLINT
const int kApiInt64Size = sizeof(int64_t);  // NOLINT

// Tag information for HeapObject.
const int kHeapObjectTag = 1;
const int kHeapObjectTagSize = 2;
const intptr_t kHeapObjectTagMask = (1 << kHeapObjectTagSize) - 1;

// Tag information for Smi.
const int kSmiTag = 0;
const int kSmiTagSize = 1;
const intptr_t kSmiTagMask = (1 << kSmiTagSize) - 1;

template <size_t ptr_size> struct SmiTagging;

template<int kSmiShiftSize>
V8_INLINE internal::Object* IntToSmi(int value) {
  int smi_shift_bits = kSmiTagSize + kSmiShiftSize;
  uintptr_t tagged_value =
      (static_cast<uintptr_t>(value) << smi_shift_bits) | kSmiTag;
  return reinterpret_cast<internal::Object*>(tagged_value);
}

// Smi constants for 32-bit systems.
template <> struct SmiTagging<4> {
  enum { kSmiShiftSize = 0, kSmiValueSize = 31 };
  static int SmiShiftSize() { return kSmiShiftSize; }
  static int SmiValueSize() { return kSmiValueSize; }
  V8_INLINE static int SmiToInt(const internal::Object* value) {
    int shift_bits = kSmiTagSize + kSmiShiftSize;
    // Throw away top 32 bits and shift down (requires >> to be sign extending).
    return static_cast<int>(reinterpret_cast<intptr_t>(value)) >> shift_bits;
  }
  V8_INLINE static internal::Object* IntToSmi(int value) {
    return internal::IntToSmi<kSmiShiftSize>(value);
  }
  V8_INLINE static bool IsValidSmi(intptr_t value) {
    // To be representable as an tagged small integer, the two
    // most-significant bits of 'value' must be either 00 or 11 due to
    // sign-extension. To check this we add 01 to the two
    // most-significant bits, and check if the most-significant bit is 0
    //
    // CAUTION: The original code below:
    // bool result = ((value + 0x40000000) & 0x80000000) == 0;
    // may lead to incorrect results according to the C language spec, and
    // in fact doesn't work correctly with gcc4.1.1 in some cases: The
    // compiler may produce undefined results in case of signed integer
    // overflow. The computation must be done w/ unsigned ints.
    return static_cast<uintptr_t>(value + 0x40000000U) < 0x80000000U;
  }
};

// Smi constants for 64-bit systems.
template <> struct SmiTagging<8> {
  enum { kSmiShiftSize = 31, kSmiValueSize = 32 };
  static int SmiShiftSize() { return kSmiShiftSize; }
  static int SmiValueSize() { return kSmiValueSize; }
  V8_INLINE static int SmiToInt(const internal::Object* value) {
    int shift_bits = kSmiTagSize + kSmiShiftSize;
    // Shift down and throw away top 32 bits.
    return static_cast<int>(reinterpret_cast<intptr_t>(value) >> shift_bits);
  }
  V8_INLINE static internal::Object* IntToSmi(int value) {
    return internal::IntToSmi<kSmiShiftSize>(value);
  }
  V8_INLINE static bool IsValidSmi(intptr_t value) {
    // To be representable as a long smi, the value must be a 32-bit integer.
    return (value == static_cast<int32_t>(value));
  }
};

typedef SmiTagging<kApiPointerSize> PlatformSmiTagging;
const int kSmiShiftSize = PlatformSmiTagging::kSmiShiftSize;
const int kSmiValueSize = PlatformSmiTagging::kSmiValueSize;
V8_INLINE static bool SmiValuesAre31Bits() { return kSmiValueSize == 31; }
V8_INLINE static bool SmiValuesAre32Bits() { return kSmiValueSize == 32; }

class Internals {
 public:
  // These values match non-compiler-dependent values defined within
  // the implementation of v8.
  static const int kHeapObjectMapOffset = 0;
  static const int kMapInstanceTypeAndBitFieldOffset =
      1 * kApiPointerSize + kApiIntSize;
  static const int kStringResourceOffset = 3 * kApiPointerSize;

  static const int kOddballKindOffset = 3 * kApiPointerSize;
  static const int kForeignAddressOffset = kApiPointerSize;
  static const int kJSObjectHeaderSize = 3 * kApiPointerSize;
  static const int kFixedArrayHeaderSize = 2 * kApiPointerSize;
  static const int kContextHeaderSize = 2 * kApiPointerSize;
  static const int kContextEmbedderDataIndex = 77;
  static const int kFullStringRepresentationMask = 0x07;
  static const int kStringEncodingMask = 0x4;
  static const int kExternalTwoByteRepresentationTag = 0x02;
  static const int kExternalOneByteRepresentationTag = 0x06;

  static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
  static const int kAmountOfExternalAllocatedMemoryOffset =
      4 * kApiPointerSize;
  static const int kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset =
      kAmountOfExternalAllocatedMemoryOffset + kApiInt64Size;
  static const int kIsolateRootsOffset =
      kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset + kApiInt64Size +
      kApiPointerSize;
  static const int kUndefinedValueRootIndex = 5;
  static const int kNullValueRootIndex = 7;
  static const int kTrueValueRootIndex = 8;
  static const int kFalseValueRootIndex = 9;
  static const int kEmptyStringRootIndex = 10;

  // The external allocation limit should be below 256 MB on all architectures
  // to avoid that resource-constrained embedders run low on memory.
  static const int kExternalAllocationLimit = 192 * 1024 * 1024;

  static const int kNodeClassIdOffset = 1 * kApiPointerSize;
  static const int kNodeFlagsOffset = 1 * kApiPointerSize + 3;
  static const int kNodeStateMask = 0x7;
  static const int kNodeStateIsWeakValue = 2;
  static const int kNodeStateIsPendingValue = 3;
  static const int kNodeStateIsNearDeathValue = 4;
  static const int kNodeIsIndependentShift = 3;
  static const int kNodeIsPartiallyDependentShift = 4;

  static const int kJSObjectType = 0xbe;
  static const int kFirstNonstringType = 0x80;
  static const int kOddballType = 0x83;
  static const int kForeignType = 0x86;

  static const int kUndefinedOddballKind = 5;
  static const int kNullOddballKind = 3;

  static const uint32_t kNumIsolateDataSlots = 4;

  V8_EXPORT static void CheckInitializedImpl(v8::Isolate* isolate);
  V8_INLINE static void CheckInitialized(v8::Isolate* isolate) {
#ifdef V8_ENABLE_CHECKS
    CheckInitializedImpl(isolate);
#endif
  }

  V8_INLINE static bool HasHeapObjectTag(const internal::Object* value) {
    return ((reinterpret_cast<intptr_t>(value) & kHeapObjectTagMask) ==
            kHeapObjectTag);
  }

  V8_INLINE static int SmiValue(const internal::Object* value) {
    return PlatformSmiTagging::SmiToInt(value);
  }

  V8_INLINE static internal::Object* IntToSmi(int value) {
    return PlatformSmiTagging::IntToSmi(value);
  }

  V8_INLINE static bool IsValidSmi(intptr_t value) {
    return PlatformSmiTagging::IsValidSmi(value);
  }

  V8_INLINE static int GetInstanceType(const internal::Object* obj) {
    typedef internal::Object O;
    O* map = ReadField<O*>(obj, kHeapObjectMapOffset);
    // Map::InstanceType is defined so that it will always be loaded into
    // the LS 8 bits of one 16-bit word, regardless of endianess.
    return ReadField<uint16_t>(map, kMapInstanceTypeAndBitFieldOffset) & 0xff;
  }

  V8_INLINE static int GetOddballKind(const internal::Object* obj) {
    typedef internal::Object O;
    return SmiValue(ReadField<O*>(obj, kOddballKindOffset));
  }

  V8_INLINE static bool IsExternalTwoByteString(int instance_type) {
    int representation = (instance_type & kFullStringRepresentationMask);
    return representation == kExternalTwoByteRepresentationTag;
  }

  V8_INLINE static uint8_t GetNodeFlag(internal::Object** obj, int shift) {
      uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
      return *addr & static_cast<uint8_t>(1U << shift);
  }

  V8_INLINE static void UpdateNodeFlag(internal::Object** obj,
                                       bool value, int shift) {
      uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
      uint8_t mask = static_cast<uint8_t>(1U << shift);
      *addr = static_cast<uint8_t>((*addr & ~mask) | (value << shift));
  }

  V8_INLINE static uint8_t GetNodeState(internal::Object** obj) {
    uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
    return *addr & kNodeStateMask;
  }

  V8_INLINE static void UpdateNodeState(internal::Object** obj,
                                        uint8_t value) {
    uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
    *addr = static_cast<uint8_t>((*addr & ~kNodeStateMask) | value);
  }

  V8_INLINE static void SetEmbedderData(v8::Isolate* isolate,
                                        uint32_t slot,
                                        void* data) {
    uint8_t *addr = reinterpret_cast<uint8_t *>(isolate) +
                    kIsolateEmbedderDataOffset + slot * kApiPointerSize;
    *reinterpret_cast<void**>(addr) = data;
  }

  V8_INLINE static void* GetEmbedderData(const v8::Isolate* isolate,
                                         uint32_t slot) {
    const uint8_t* addr = reinterpret_cast<const uint8_t*>(isolate) +
        kIsolateEmbedderDataOffset + slot * kApiPointerSize;
    return *reinterpret_cast<void* const*>(addr);
  }

  V8_INLINE static internal::Object** GetRoot(v8::Isolate* isolate,
                                              int index) {
    uint8_t* addr = reinterpret_cast<uint8_t*>(isolate) + kIsolateRootsOffset;
    return reinterpret_cast<internal::Object**>(addr + index * kApiPointerSize);
  }

  template <typename T>
  V8_INLINE static T ReadField(const internal::Object* ptr, int offset) {
    const uint8_t* addr =
        reinterpret_cast<const uint8_t*>(ptr) + offset - kHeapObjectTag;
    return *reinterpret_cast<const T*>(addr);
  }

  template <typename T>
  V8_INLINE static T ReadEmbedderData(const v8::Context* context, int index) {
    typedef internal::Object O;
    typedef internal::Internals I;
    O* ctx = *reinterpret_cast<O* const*>(context);
    int embedder_data_offset = I::kContextHeaderSize +
        (internal::kApiPointerSize * I::kContextEmbedderDataIndex);
    O* embedder_data = I::ReadField<O*>(ctx, embedder_data_offset);
    int value_offset =
        I::kFixedArrayHeaderSize + (internal::kApiPointerSize * index);
    return I::ReadField<T>(embedder_data, value_offset);
  }
};

}  // namespace internal


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, T* that) {
  if (that == NULL) return Local<T>();
  T* that_ptr = that;
  internal::Object** p = reinterpret_cast<internal::Object**>(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) {
  TYPE_CHECK(T, S);
  V8::Eternalize(isolate, reinterpret_cast<Value*>(*handle), &this->index_);
}


template<class T>
Local<T> Eternal<T>::Get(Isolate* isolate) {
  return Local<T>(reinterpret_cast<T*>(*V8::GetEternal(isolate, index_)));
}


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 >= kInternalFieldsInWeakCallback) {
    V8::InternalFieldOutOfBounds(index);
  }
#endif
  return internal_fields_[index];
}


template <class T>
T* PersistentBase<T>::New(Isolate* isolate, T* that) {
  if (that == NULL) return NULL;
  internal::Object** p = reinterpret_cast<internal::Object**>(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) {
  TYPE_CHECK(T, S);
  this->Reset();
  if (that.IsEmpty()) return;
  internal::Object** p = reinterpret_cast<internal::Object**>(that.val_);
  this->val_ = reinterpret_cast<T*>(V8::CopyPersistent(p));
  M::Copy(that, this);
}


template <class T>
bool PersistentBase<T>::IsIndependent() const {
  typedef internal::Internals I;
  if (this->IsEmpty()) return false;
  return I::GetNodeFlag(reinterpret_cast<internal::Object**>(this->val_),
                        I::kNodeIsIndependentShift);
}


template <class T>
bool PersistentBase<T>::IsNearDeath() const {
  typedef internal::Internals I;
  if (this->IsEmpty()) return false;
  uint8_t node_state =
      I::GetNodeState(reinterpret_cast<internal::Object**>(this->val_));
  return node_state == I::kNodeStateIsNearDeathValue ||
      node_state == I::kNodeStateIsPendingValue;
}


template <class T>
bool PersistentBase<T>::IsWeak() const {
  typedef internal::Internals I;
  if (this->IsEmpty()) return false;
  return I::GetNodeState(reinterpret_cast<internal::Object**>(this->val_)) ==
      I::kNodeStateIsWeakValue;
}


template <class T>
void PersistentBase<T>::Reset() {
  if (this->IsEmpty()) return;
  V8::DisposeGlobal(reinterpret_cast<internal::Object**>(this->val_));
  val_ = 0;
}


template <class T>
template <class S>
void PersistentBase<T>::Reset(Isolate* isolate, const Handle<S>& other) {
  TYPE_CHECK(T, S);
  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) {
  TYPE_CHECK(T, S);
  Reset();
  if (other.IsEmpty()) return;
  this->val_ = New(isolate, other.val_);
}


template <class T>
template <typename S, typename P>
void PersistentBase<T>::SetWeak(
    P* parameter,
    typename WeakCallbackData<S, P>::Callback callback) {
  TYPE_CHECK(S, T);
  typedef typename WeakCallbackData<Value, void>::Callback Callback;
  V8::MakeWeak(reinterpret_cast<internal::Object**>(this->val_), parameter,
               reinterpret_cast<Callback>(callback));
}


template <class T>
template <typename P>
void PersistentBase<T>::SetWeak(
    P* parameter,
    typename WeakCallbackData<T, P>::Callback callback) {
  SetWeak<T, P>(parameter, callback);
}


template <class T>
template <typename P>
void PersistentBase<T>::SetPhantom(
    P* parameter, typename WeakCallbackInfo<P>::Callback callback,
    int internal_field_index1, int internal_field_index2) {
  typedef typename WeakCallbackInfo<void>::Callback Callback;
  V8::MakeWeak(reinterpret_cast<internal::Object**>(this->val_), parameter,
               internal_field_index1, internal_field_index2,
               reinterpret_cast<Callback>(callback));
}


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::Object**>(this->val_), parameter,
               reinterpret_cast<Callback>(callback), type);
}


template <class T>
template <typename P>
P* PersistentBase<T>::ClearWeak() {
  return reinterpret_cast<P*>(
    V8::ClearWeak(reinterpret_cast<internal::Object**>(this->val_)));
}


template <class T>
void PersistentBase<T>::MarkIndependent() {
  typedef internal::Internals I;
  if (this->IsEmpty()) return;
  I::UpdateNodeFlag(reinterpret_cast<internal::Object**>(this->val_),
                    true,
                    I::kNodeIsIndependentShift);
}


template <class T>
void PersistentBase<T>::MarkPartiallyDependent() {
  typedef internal::Internals I;
  if (this->IsEmpty()) return;
  I::UpdateNodeFlag(reinterpret_cast<internal::Object**>(this->val_),
                    true,
                    I::kNodeIsPartiallyDependentShift);
}


template <class T>
void PersistentBase<T>::SetWrapperClassId(uint16_t class_id) {
  typedef internal::Internals I;
  if (this->IsEmpty()) return;
  internal::Object** obj = reinterpret_cast<internal::Object**>(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::Object** obj = reinterpret_cast<internal::Object**>(this->val_);
  uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
  return *reinterpret_cast<uint16_t*>(addr);
}


template<typename T>
ReturnValue<T>::ReturnValue(internal::Object** slot) : value_(slot) {}

template<typename T>
template<typename S>
void ReturnValue<T>::Set(const Persistent<S>& handle) {
  TYPE_CHECK(T, S);
  if (V8_UNLIKELY(handle.IsEmpty())) {
    *value_ = GetDefaultValue();
  } else {
    *value_ = *reinterpret_cast<internal::Object**>(*handle);
  }
}

template<typename T>
template<typename S>
void ReturnValue<T>::Set(const Handle<S> handle) {
  TYPE_CHECK(T, S);
  if (V8_UNLIKELY(handle.IsEmpty())) {
    *value_ = GetDefaultValue();
  } else {
    *value_ = *reinterpret_cast<internal::Object**>(*handle);
  }
}

template<typename T>
void ReturnValue<T>::Set(double i) {
  TYPE_CHECK(T, Number);
  Set(Number::New(GetIsolate(), i));
}

template<typename T>
void ReturnValue<T>::Set(int32_t i) {
  TYPE_CHECK(T, Integer);
  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) {
  TYPE_CHECK(T, Integer);
  // 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) {
  TYPE_CHECK(T, Boolean);
  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() {
  TYPE_CHECK(T, Primitive);
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kNullValueRootIndex);
}

template<typename T>
void ReturnValue<T>::SetUndefined() {
  TYPE_CHECK(T, Primitive);
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kUndefinedValueRootIndex);
}

template<typename T>
void ReturnValue<T>::SetEmptyString() {
  TYPE_CHECK(T, String);
  typedef internal::Internals I;
  *value_ = *I::GetRoot(GetIsolate(), I::kEmptyStringRootIndex);
}

template<typename T>
Isolate* ReturnValue<T>::GetIsolate() {
  // Isolate is always the pointer below the default value on the stack.
  return *reinterpret_cast<Isolate**>(&value_[-2]);
}

template<typename T>
template<typename S>
void ReturnValue<T>::Set(S* whatever) {
  // Uncompilable to prevent inadvertent misuse.
  TYPE_CHECK(S*, Primitive);
}

template<typename T>
internal::Object* ReturnValue<T>::GetDefaultValue() {
  // Default value is always the pointer below value_ on the stack.
  return value_[-1];
}


template<typename T>
FunctionCallbackInfo<T>::FunctionCallbackInfo(internal::Object** implicit_args,
                                              internal::Object** values,
                                              int length,
                                              bool is_construct_call)
    : implicit_args_(implicit_args),
      values_(values),
      length_(length),
      is_construct_call_(is_construct_call) { }


template<typename T>
Local<Value> FunctionCallbackInfo<T>::operator[](int i) const {
  if (i < 0 || length_ <= i) return Local<Value>(*Undefined(GetIsolate()));
  return Local<Value>(reinterpret_cast<Value*>(values_ - i));
}


template<typename T>
Local<Function> FunctionCallbackInfo<T>::Callee() const {
  return Local<Function>(reinterpret_cast<Function*>(
      &implicit_args_[kCalleeIndex]));
}


template<typename T>
Local<Object> FunctionCallbackInfo<T>::This() const {
  return Local<Object>(reinterpret_cast<Object*>(values_ + 1));
}


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>::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 is_construct_call_ & 0x1;
}


template<typename T>
int FunctionCallbackInfo<T>::Length() const {
  return length_;
}


Handle<Value> ScriptOrigin::ResourceName() const {
  return resource_name_;
}


Handle<Integer> ScriptOrigin::ResourceLineOffset() const {
  return resource_line_offset_;
}


Handle<Integer> ScriptOrigin::ResourceColumnOffset() const {
  return resource_column_offset_;
}


Handle<Boolean> ScriptOrigin::ResourceIsEmbedderDebugScript() const {
  return resource_is_embedder_debug_script_;
}


Handle<Boolean> ScriptOrigin::ResourceIsSharedCrossOrigin() const {
  return resource_is_shared_cross_origin_;
}


Handle<Integer> ScriptOrigin::ScriptID() const {
  return script_id_;
}


Handle<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_is_embedder_debug_script(origin.ResourceIsEmbedderDebugScript()),
      resource_is_shared_cross_origin(origin.ResourceIsSharedCrossOrigin()),
      source_map_url(origin.SourceMapUrl()),
      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;
}


Handle<Boolean> Boolean::New(Isolate* isolate, bool value) {
  return value ? True(isolate) : False(isolate);
}


void Template::Set(Isolate* isolate, const char* name, v8::Handle<Data> value) {
  Set(v8::String::NewFromUtf8(isolate, name), value);
}


Local<Value> Object::GetInternalField(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Object O;
  typedef internal::HeapObject HO;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O**>(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.
  if (I::GetInstanceType(obj) == I::kJSObjectType) {
    int offset = I::kJSObjectHeaderSize + (internal::kApiPointerSize * index);
    O* value = I::ReadField<O*>(obj, offset);
    O** result = HandleScope::CreateHandle(reinterpret_cast<HO*>(obj), value);
    return Local<Value>(reinterpret_cast<Value*>(result));
  }
#endif
  return SlowGetInternalField(index);
}


void* Object::GetAlignedPointerFromInternalField(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O**>(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.
  if (V8_LIKELY(I::GetInstanceType(obj) == I::kJSObjectType)) {
    int offset = I::kJSObjectHeaderSize + (internal::kApiPointerSize * index);
    return I::ReadField<void*>(obj, offset);
  }
#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::Object* 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::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O* const*>(this);
  String::ExternalStringResource* result;
  if (I::IsExternalTwoByteString(I::GetInstanceType(obj))) {
    void* value = I::ReadField<void*>(obj, I::kStringResourceOffset);
    result = reinterpret_cast<String::ExternalStringResource*>(value);
  } else {
    result = NULL;
  }
#ifdef V8_ENABLE_CHECKS
  VerifyExternalStringResource(result);
#endif
  return result;
}


String::ExternalStringResourceBase* String::GetExternalStringResourceBase(
    String::Encoding* encoding_out) const {
  typedef internal::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O* const*>(this);
  int type = I::GetInstanceType(obj) & I::kFullStringRepresentationMask;
  *encoding_out = static_cast<Encoding>(type & I::kStringEncodingMask);
  ExternalStringResourceBase* resource = NULL;
  if (type == I::kExternalOneByteRepresentationTag ||
      type == I::kExternalTwoByteRepresentationTag) {
    void* value = I::ReadField<void*>(obj, I::kStringResourceOffset);
    resource = static_cast<ExternalStringResourceBase*>(value);
  }
#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::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O* const*>(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::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O* const*>(this);
  if (!I::HasHeapObjectTag(obj)) return false;
  if (I::GetInstanceType(obj) != I::kOddballType) return false;
  return (I::GetOddballKind(obj) == I::kNullOddballKind);
}


bool Value::IsString() const {
#ifdef V8_ENABLE_CHECKS
  return FullIsString();
#else
  return QuickIsString();
#endif
}

bool Value::QuickIsString() const {
  typedef internal::Object O;
  typedef internal::Internals I;
  O* obj = *reinterpret_cast<O* const*>(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);
}


Local<Boolean> Value::ToBoolean() const {
  return ToBoolean(Isolate::GetCurrent());
}


Local<Number> Value::ToNumber() const {
  return ToNumber(Isolate::GetCurrent());
}


Local<String> Value::ToString() const {
  return ToString(Isolate::GetCurrent());
}


Local<String> Value::ToDetailString() const {
  return ToDetailString(Isolate::GetCurrent());
}


Local<Object> Value::ToObject() const {
  return ToObject(Isolate::GetCurrent());
}


Local<Integer> Value::ToInteger() const {
  return ToInteger(Isolate::GetCurrent());
}


Local<Uint32> Value::ToUint32() const {
  return ToUint32(Isolate::GetCurrent());
}


Local<Int32> Value::ToInt32() const { return ToInt32(Isolate::GetCurrent()); }


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);
}


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);
}


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);
}


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);
}


Promise* Promise::Cast(v8::Value* value) {
#ifdef V8_ENABLE_CHECKS
  CheckCast(value);
#endif
  return static_cast<Promise*>(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);
}


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);
}


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]);
}


Handle<Primitive> Undefined(Isolate* isolate) {
  typedef internal::Object* S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kUndefinedValueRootIndex);
  return Handle<Primitive>(reinterpret_cast<Primitive*>(slot));
}


Handle<Primitive> Null(Isolate* isolate) {
  typedef internal::Object* S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kNullValueRootIndex);
  return Handle<Primitive>(reinterpret_cast<Primitive*>(slot));
}


Handle<Boolean> True(Isolate* isolate) {
  typedef internal::Object* S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kTrueValueRootIndex);
  return Handle<Boolean>(reinterpret_cast<Boolean*>(slot));
}


Handle<Boolean> False(Isolate* isolate) {
  typedef internal::Object* S;
  typedef internal::Internals I;
  I::CheckInitialized(isolate);
  S* slot = I::GetRoot(isolate, I::kFalseValueRootIndex);
  return Handle<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;
}


int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
    int64_t change_in_bytes) {
  typedef internal::Internals I;
  int64_t* amount_of_external_allocated_memory =
      reinterpret_cast<int64_t*>(reinterpret_cast<uint8_t*>(this) +
                                 I::kAmountOfExternalAllocatedMemoryOffset);
  int64_t* amount_of_external_allocated_memory_at_last_global_gc =
      reinterpret_cast<int64_t*>(
          reinterpret_cast<uint8_t*>(this) +
          I::kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset);
  int64_t amount = *amount_of_external_allocated_memory + change_in_bytes;
  if (change_in_bytes > 0 &&
      amount - *amount_of_external_allocated_memory_at_last_global_gc >
          I::kExternalAllocationLimit) {
    CollectAllGarbage("external memory allocation limit reached.");
  }
  *amount_of_external_allocated_memory = amount;
  return *amount_of_external_allocated_memory;
}


template<typename T>
void Isolate::SetObjectGroupId(const Persistent<T>& object,
                               UniqueId id) {
  TYPE_CHECK(Value, T);
  SetObjectGroupId(reinterpret_cast<v8::internal::Object**>(object.val_), id);
}


template<typename T>
void Isolate::SetReferenceFromGroup(UniqueId id,
                                    const Persistent<T>& object) {
  TYPE_CHECK(Value, T);
  SetReferenceFromGroup(id,
                        reinterpret_cast<v8::internal::Object**>(object.val_));
}


template<typename T, typename S>
void Isolate::SetReference(const Persistent<T>& parent,
                           const Persistent<S>& child) {
  TYPE_CHECK(Object, T);
  TYPE_CHECK(Value, S);
  SetReference(reinterpret_cast<v8::internal::Object**>(parent.val_),
               reinterpret_cast<v8::internal::Object**>(child.val_));
}


Local<Value> Context::GetEmbedderData(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Object O;
  typedef internal::HeapObject HO;
  typedef internal::Internals I;
  HO* context = *reinterpret_cast<HO**>(this);
  O** result =
      HandleScope::CreateHandle(context, I::ReadEmbedderData<O*>(this, index));
  return Local<Value>(reinterpret_cast<Value*>(result));
#else
  return SlowGetEmbedderData(index);
#endif
}


void* Context::GetAlignedPointerFromEmbedderData(int index) {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Internals I;
  return I::ReadEmbedderData<void*>(this, index);
#else
  return SlowGetAlignedPointerFromEmbedderData(index);
#endif
}


void V8::SetAllowCodeGenerationFromStringsCallback(
    AllowCodeGenerationFromStringsCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->SetAllowCodeGenerationFromStringsCallback(callback);
}


bool V8::IsDead() {
  Isolate* isolate = Isolate::GetCurrent();
  return isolate->IsDead();
}


bool V8::AddMessageListener(MessageCallback that, Handle<Value> data) {
  Isolate* isolate = Isolate::GetCurrent();
  return isolate->AddMessageListener(that, data);
}


void V8::RemoveMessageListeners(MessageCallback that) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->RemoveMessageListeners(that);
}


void V8::SetFailedAccessCheckCallbackFunction(
    FailedAccessCheckCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->SetFailedAccessCheckCallbackFunction(callback);
}


void V8::SetCaptureStackTraceForUncaughtExceptions(
    bool capture, int frame_limit, StackTrace::StackTraceOptions options) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->SetCaptureStackTraceForUncaughtExceptions(capture, frame_limit,
                                                     options);
}


void V8::SetFatalErrorHandler(FatalErrorCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->SetFatalErrorHandler(callback);
}


void V8::RemoveGCPrologueCallback(GCPrologueCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->RemoveGCPrologueCallback(
      reinterpret_cast<v8::Isolate::GCPrologueCallback>(callback));
}


void V8::RemoveGCEpilogueCallback(GCEpilogueCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->RemoveGCEpilogueCallback(
      reinterpret_cast<v8::Isolate::GCEpilogueCallback>(callback));
}


void V8::AddMemoryAllocationCallback(MemoryAllocationCallback callback,
                                     ObjectSpace space,
                                     AllocationAction action) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->AddMemoryAllocationCallback(callback, space, action);
}


void V8::RemoveMemoryAllocationCallback(MemoryAllocationCallback callback) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->RemoveMemoryAllocationCallback(callback);
}


void V8::TerminateExecution(Isolate* isolate) { isolate->TerminateExecution(); }


bool V8::IsExecutionTerminating(Isolate* isolate) {
  if (isolate == NULL) {
    isolate = Isolate::GetCurrent();
  }
  return isolate->IsExecutionTerminating();
}


void V8::CancelTerminateExecution(Isolate* isolate) {
  isolate->CancelTerminateExecution();
}


void V8::VisitExternalResources(ExternalResourceVisitor* visitor) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->VisitExternalResources(visitor);
}


void V8::VisitHandlesWithClassIds(PersistentHandleVisitor* visitor) {
  Isolate* isolate = Isolate::GetCurrent();
  isolate->VisitHandlesWithClassIds(visitor);
}


void V8::VisitHandlesWithClassIds(Isolate* isolate,
                                  PersistentHandleVisitor* visitor) {
  isolate->VisitHandlesWithClassIds(visitor);
}


void V8::VisitHandlesForPartialDependence(Isolate* isolate,
                                          PersistentHandleVisitor* visitor) {
  isolate->VisitHandlesForPartialDependence(visitor);
}

}  // namespace v8


#undef TYPE_CHECK


#endif  // V8_H_