text: // 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.
  
  /** \mainpage V8 API Reference Guide
   *
   * V8 is Google's open source JavaScript engine.
   *
   * This set of documents provides reference material generated from the
   * V8 header file, include/v8.h.
   *
   * For other documentation see http://code.google.com/apis/v8/
   */
  
  #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
  
  /**
   * The v8 JavaScript engine.
   */
  namespace v8 {
  
  class AccessorSignature;
  class Array;
  class Boolean;
  class BooleanObject;
  class Context;
  class CpuProfiler;
  class Data;
  class Date;
  class DeclaredAccessorDescriptor;
  class External;
  class Function;
  class FunctionTemplate;
  class HeapProfiler;
  class ImplementationUtilities;
  class Int32;
  class Integer;
  class Isolate;
  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 StackFrame;
  class StackTrace;
  class String;
  class StringObject;
  class Symbol;
  class SymbolObject;
  class Private;
  class Uint32;
  class Utils;
  class Value;
  template <class T> class Handle;
  template <class T> class Local;
  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 UniquePersistent;
  template<class K, class V, class T> class PersistentValueMap;
  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 DeclaredAccessorDescriptor;
  class ObjectOperationDescriptor;
  class RawOperationDescriptor;
  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 CallbackData {
   public:
    V8_INLINE v8::Isolate* GetIsolate() const { return isolate_; }
  
   protected:
    explicit CallbackData(v8::Isolate* isolate) : isolate_(isolate) {}
  
   private:
    v8::Isolate* isolate_;
  };
  }
  
  
  /**
   * General purpose unique identifier.
   */
  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);      \
    }
  
  
  /**
   * An object reference managed by the v8 garbage collector.
   *
   * All objects returned from v8 have to be tracked by the garbage
   * collector so that it knows that the objects are still alive.  Also,
   * because the garbage collector may move objects, it is unsafe to
   * point directly to an object.  Instead, all objects are stored in
   * handles which are known by the garbage collector and updated
   * whenever an object moves.  Handles should always be passed by value
   * (except in cases like out-parameters) and they should never be
   * allocated on the heap.
   *
   * There are two types of handles: local and persistent handles.
   * Local handles are light-weight and transient and typically used in
   * local operations.  They are managed by HandleScopes.  Persistent
   * handles can be used when storing objects across several independent
   * operations and have to be explicitly deallocated when they're no
   * longer used.
   *
   * It is safe to extract the object stored in the handle by
   * dereferencing the handle (for instance, to extract the Object* from
   * a Handle<Object>); the value will still be governed by a handle
   * behind the scenes and the same rules apply to these values as to
   * their handles.
   */
  template <class T> class Handle {
   public:
    /**
     * Creates an empty handle.
     */
    V8_INLINE Handle() : val_(0) {}
  
    /**
     * Creates a handle for the contents of the specified handle.  This
     * constructor allows you to pass handles as arguments by value and
     * to assign between handles.  However, if you try to assign between
     * incompatible handles, for instance from a Handle<String> to a
     * Handle<Number> it will cause a compile-time error.  Assigning
     * between compatible handles, for instance assigning a
     * Handle<String> to a variable declared as Handle<Value>, is legal
     * because String is a subclass of Value.
     */
    template <class S> V8_INLINE Handle(Handle<S> that)
        : val_(reinterpret_cast<T*>(*that)) {
      /**
       * This check fails when trying to convert between incompatible
       * handles. For example, converting from a Handle<String> to a
       * Handle<Number>.
       */
      TYPE_CHECK(T, S);
    }
  
    /**
     * Returns true if the handle is empty.
     */
    V8_INLINE bool IsEmpty() const { return val_ == 0; }
  
    /**
     * Sets the handle to be empty. IsEmpty() will then return true.
     */
    V8_INLINE void Clear() { val_ = 0; }
  
    V8_INLINE T* operator->() const { return val_; }
  
    V8_INLINE T* operator*() const { return val_; }
  
    /**
     * Checks whether two handles are the same.
     * Returns true if both are empty, or if the objects
     * to which they refer are identical.
     * The handles' references are not checked.
     */
    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 == 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;
    }
  
    /**
     * Checks whether two handles are different.
     * Returns true if only one of the handles is empty, or if
     * the objects to which they refer are different.
     * The handles' references are not checked.
     */
    template <class S> V8_INLINE bool operator!=(const Handle<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 Handle<T> Cast(Handle<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 Handle<T>();
  #endif
      return Handle<T>(T::Cast(*that));
    }
  
    template <class S> V8_INLINE Handle<S> As() {
      return Handle<S>::Cast(*this);
    }
  
    V8_INLINE static Handle<T> New(Isolate* isolate, Handle<T> that) {
      return New(isolate, that.val_);
    }
    V8_INLINE static Handle<T> New(Isolate* isolate,
                                   const PersistentBase<T>& that) {
      return New(isolate, that.val_);
    }
  
   private:
    friend class Utils;
    template<class F, class M> friend class Persistent;
    template<class F> friend class PersistentBase;
    template<class F> friend class Handle;
    template<class F> friend class Local;
    template<class F> friend class FunctionCallbackInfo;
    template<class F> friend class PropertyCallbackInfo;
    template<class F> friend class internal::CustomArguments;
    friend Handle<Primitive> Undefined(Isolate* isolate);
    friend Handle<Primitive> Null(Isolate* isolate);
    friend Handle<Boolean> True(Isolate* isolate);
    friend Handle<Boolean> False(Isolate* isolate);
    friend class Context;
    friend class HandleScope;
    friend class Object;
    friend class Private;
  
    /**
     * Creates a new handle for the specified value.
     */
    V8_INLINE explicit Handle(T* val) : val_(val) {}
  
    V8_INLINE static Handle<T> New(Isolate* isolate, T* that);
  
    T* val_;
  };
  
  
  /**
   * A light-weight stack-allocated object handle.  All operations
   * that return objects from within v8 return them in local handles.  They
   * are created within HandleScopes, and all local handles allocated within a
   * handle scope are destroyed when the handle scope is destroyed.  Hence it
   * is not necessary to explicitly deallocate local handles.
   */
  template <class T> class Local : public Handle<T> {
   public:
    V8_INLINE Local();
    template <class S> V8_INLINE Local(Local<S> that)
        : Handle<T>(reinterpret_cast<T*>(*that)) {
      /**
       * This check fails when trying to convert between incompatible
       * handles. For example, converting from a Handle<String> to a
       * Handle<Number>.
       */
      TYPE_CHECK(T, S);
    }
  
  
    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(Handle<S> that)
        : Handle<T>(reinterpret_cast<T*>(*that)) {
      TYPE_CHECK(T, S);
    }
  
    template <class S> V8_INLINE Local<S> As() {
      return Local<S>::Cast(*this);
    }
  
    /**
     * Create a local handle for the content of another handle.
     * The referee is kept alive by the local handle even when
     * the original handle is destroyed/disposed.
     */
    V8_INLINE static Local<T> New(Isolate* isolate, Handle<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 Handle;
    template<class F> friend class Local;
    template<class F> friend class FunctionCallbackInfo;
    template<class F> friend class PropertyCallbackInfo;
    friend class String;
    friend class Object;
    friend class Context;
    template<class F> friend class internal::CustomArguments;
    friend class HandleScope;
    friend class EscapableHandleScope;
    template<class F1, class F2, class F3> friend class PersistentValueMap;
    template<class F1, class F2> friend class PersistentValueVector;
  
    template <class S> V8_INLINE Local(S* that) : Handle<T>(that) { }
    V8_INLINE static Local<T> New(Isolate* isolate, T* that);
  };
  
  
  // 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_;
  };
  
  
  template <typename T>
  class PhantomCallbackData : public internal::CallbackData {
   public:
    typedef void (*Callback)(const PhantomCallbackData<T>& data);
  
    V8_INLINE T* GetParameter() const { return parameter_; }
  
    PhantomCallbackData<T>(Isolate* isolate, T* parameter)
        : internal::CallbackData(isolate), parameter_(parameter) {}
  
   private:
    T* parameter_;
  };
  
  
  template <class T, class P>
  class WeakCallbackData : public PhantomCallbackData<P> {
   public:
    typedef void (*Callback)(const WeakCallbackData<T, P>& data);
  
    V8_INLINE Local<T> GetValue() const { return handle_; }
  
   private:
    friend class internal::GlobalHandles;
    WeakCallbackData(Isolate* isolate, P* parameter, Local<T> handle)
        : PhantomCallbackData<P>(isolate, parameter), handle_(handle) {}
    Local<T> handle_;
  };
  
  
  template <typename T, typename U>
  class InternalFieldsCallbackData : public internal::CallbackData {
   public:
    typedef void (*Callback)(const InternalFieldsCallbackData<T, U>& data);
  
    InternalFieldsCallbackData(Isolate* isolate, T* internalField1,
                               U* internalField2)
        : internal::CallbackData(isolate),
          internal_field1_(internalField1),
          internal_field2_(internalField2) {}
  
    V8_INLINE T* GetInternalField1() const { return internal_field1_; }
    V8_INLINE U* GetInternalField2() const { return internal_field2_; }
  
   private:
    T* internal_field1_;
    U* internal_field2_;
  };
  
  
  /**
   * An object reference that is independent of any handle scope.  Where
   * a Local handle only lives as long as the HandleScope in which it was
   * allocated, a PersistentBase handle remains valid until it is explicitly
   * disposed.
   *
   * A persistent handle contains a reference to a storage cell within
   * the v8 engine which holds an object value and which is updated by
   * the garbage collector whenever the object is moved.  A new storage
   * cell can be created using the constructor or PersistentBase::Reset and
   * existing handles can be disposed using PersistentBase::Reset.
   *
   */
  template <class T> class PersistentBase {
   public:
    /**
     * If non-empty, destroy the underlying storage cell
     * IsEmpty() will return true after this call.
     */
    V8_INLINE void Reset();
    /**
     * If non-empty, destroy the underlying storage cell
     * and create a new one with the contents of other if other is non empty
     */
    template <class S>
    V8_INLINE void Reset(Isolate* isolate, const Handle<S>& other);
  
    /**
     * If non-empty, destroy the underlying storage cell
     * and create a new one with the contents of other if other is non empty
     */
    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);
    }
  
    /**
     *  Install a finalization callback on this object.
     *  NOTE: There is no guarantee as to *when* or even *if* the callback is
     *  invoked. The invocation is performed solely on a best effort basis.
     *  As always, GC-based finalization should *not* be relied upon for any
     *  critical form of resource management!
     */
    template<typename P>
    V8_INLINE void SetWeak(
        P* parameter,
        typename WeakCallbackData<T, P>::Callback callback);
  
    template<typename S, typename P>
    V8_INLINE 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 void SetPhantom(P* parameter,
                              typename PhantomCallbackData<P>::Callback callback);
  
    template <typename P, typename Q>
    V8_INLINE void SetPhantom(
        void (*callback)(const InternalFieldsCallbackData<P, Q>&),
        int internal_field_index1, int internal_field_index2);
  
    template<typename P>
    V8_INLINE P* ClearWeak();
  
    // TODO(dcarney): remove this.
    V8_INLINE void ClearWeak() { ClearWeak<void>(); }
  
    /**
     * Marks the reference to this object independent. Garbage collector is free
     * to ignore any object groups containing this object. Weak callback for an
     * independent handle should not assume that it will be preceded by a global
     * GC prologue callback or followed by a global GC epilogue callback.
     */
    V8_INLINE void MarkIndependent();
  
    /**
     * Marks the reference to this object partially dependent. Partially dependent
     * handles only depend on other partially dependent handles and these
     * dependencies are provided through object groups. It provides a way to build
     * smaller object groups for young objects that represent only a subset of all
     * external dependencies. This mark is automatically cleared after each
     * garbage collection.
     */
    V8_INLINE void MarkPartiallyDependent();
  
    V8_INLINE bool IsIndependent() const;
  
    /** Checks if the handle holds the only reference to an object. */
    V8_INLINE bool IsNearDeath() const;
  
    /** Returns true if the handle's reference is weak.  */
    V8_INLINE bool IsWeak() const;
  
    /**
     * Assigns a wrapper class ID to the handle. See RetainedObjectInfo interface
     * description in v8-profiler.h for details.
     */
    V8_INLINE void SetWrapperClassId(uint16_t class_id);
  
    /**
     * Returns the class ID previously assigned to this handle or 0 if no class ID
     * was previously assigned.
     */
    V8_INLINE uint16_t WrapperClassId() const;
  
   private:
    friend class Isolate;
    friend class Utils;
    template<class F> friend class Handle;
    template<class F> friend class Local;
    template<class F1, class F2> friend class Persistent;
    template<class F> friend class UniquePersistent;
    template<class F> friend class PersistentBase;
    template<class F> friend class ReturnValue;
    template<class F1, class F2, class F3> friend class PersistentValueMap;
    template<class F1, class F2> friend class PersistentValueVector;
    friend class Object;
  
    explicit V8_INLINE PersistentBase(T* val) : val_(val) {}
    PersistentBase(PersistentBase& other); // NOLINT
    void operator=(PersistentBase&);
    V8_INLINE static T* New(Isolate* isolate, T* that);
  
    T* val_;
  };
  
  
  /**
   * Default traits for Persistent. This class does not allow
   * use of the copy constructor or assignment operator.
   * At present kResetInDestructor is not set, but that will change in a future
   * version.
   */
  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);
    }
  };
  
  
  /**
   * Helper class traits to allow copying and assignment of Persistent.
   * This will clone the contents of storage cell, but not any of the flags, etc.
   */
  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
    }
  };
  
  
  /**
   * A PersistentBase which allows copy and assignment.
   *
   * Copy, assignment and destructor bevavior is controlled by the traits
   * class M.
   *
   * Note: Persistent class hierarchy is subject to future changes.
   */
  template <class T, class M> class Persistent : public PersistentBase<T> {
   public:
    /**
     * A Persistent with no storage cell.
     */
    V8_INLINE Persistent() : PersistentBase<T>(0) { }
    /**
     * Construct a Persistent from a Handle.
     * When the Handle is non-empty, a new storage cell is created
     * pointing to the same object, and no flags are set.
     */
    template <class S> V8_INLINE Persistent(Isolate* isolate, Handle<S> that)
        : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
      TYPE_CHECK(T, S);
    }
    /**
     * Construct a Persistent from a Persistent.
     * When the Persistent is non-empty, a new storage cell is created
     * pointing to the same object, and no flags are set.
     */
    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);
    }
    /**
     * The copy constructors and assignment operator create a Persistent
     * exactly as the Persistent constructor, but the Copy function from the
     * traits class is called, allowing the setting of flags based on the
     * copied Persistent.
     */
    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;
    }
    /**
     * The destructor will dispose the Persistent based on the
     * kResetInDestructor flags in the traits class.  Since not calling dispose
     * can result in a memory leak, it is recommended to always set this flag.
     */
    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 Handle;
    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);
  };
  
  
  /**
   * A PersistentBase which has move semantics.
   *
   * Note: Persistent class hierarchy is subject to future changes.
   */
  template<class T>
  class UniquePersistent : public PersistentBase<T> {
    struct RValue {
      V8_INLINE explicit RValue(UniquePersistent* obj) : object(obj) {}
      UniquePersistent* object;
    };
  
   public:
    /**
     * A UniquePersistent with no storage cell.
     */
    V8_INLINE UniquePersistent() : PersistentBase<T>(0) { }
    /**
     * Construct a UniquePersistent from a Handle.
     * When the Handle is non-empty, a new storage cell is created
     * pointing to the same object, and no flags are set.
     */
    template <class S>
    V8_INLINE UniquePersistent(Isolate* isolate, Handle<S> that)
        : PersistentBase<T>(PersistentBase<T>::New(isolate, *that)) {
      TYPE_CHECK(T, S);
    }
    /**
     * Construct a UniquePersistent from a PersistentBase.
     * When the Persistent is non-empty, a new storage cell is created
     * pointing to the same object, and no flags are set.
     */
    template <class S>
    V8_INLINE UniquePersistent(Isolate* isolate, const PersistentBase<S>& that)
      : PersistentBase<T>(PersistentBase<T>::New(isolate, that.val_)) {
      TYPE_CHECK(T, S);
    }
    /**
     * Move constructor.
     */
    V8_INLINE UniquePersistent(RValue rvalue)
      : PersistentBase<T>(rvalue.object->val_) {
      rvalue.object->val_ = 0;
    }
    V8_INLINE ~UniquePersistent() { this->Reset(); }
    /**
     * Move via assignment.
     */
    template<class S>
    V8_INLINE UniquePersistent& operator=(UniquePersistent<S> rhs) {
      TYPE_CHECK(T, S);
      this->Reset();
      this->val_ = rhs.val_;
      rhs.val_ = 0;
      return *this;
    }
    /**
     * Cast operator for moves.
     */
    V8_INLINE operator RValue() { return RValue(this); }
    /**
     * Pass allows returning uniques from functions, etc.
     */
    UniquePersistent Pass() { return UniquePersistent(RValue(this)); }
  
   private:
    UniquePersistent(UniquePersistent&);
    void operator=(UniquePersistent&);
  };
  
  
   /**
   * A stack-allocated class that governs a number of local handles.
   * After a handle scope has been created, all local handles will be
   * allocated within that handle scope until either the handle scope is
   * deleted or another handle scope is created.  If there is already a
   * handle scope and a new one is created, all allocations will take
   * place in the new handle scope until it is deleted.  After that,
   * new handles will again be allocated in the original handle scope.
   *
   * After the handle scope of a local handle has been deleted the
   * garbage collector will no longer track the object stored in the
   * handle and may deallocate it.  The behavior of accessing a handle
   * for which the handle scope has been deleted is undefined.
   */
  class V8_EXPORT HandleScope {
   public:
    HandleScope(Isolate* isolate);
  
    ~HandleScope();
  
    /**
     * Counts the number of allocated handles.
     */
    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;
  };
  
  
  /**
   * A HandleScope which first allocates a handle in the current scope
   * which will be later filled with the escape value.
   */
  class V8_EXPORT EscapableHandleScope : public HandleScope {
   public:
    EscapableHandleScope(Isolate* isolate);
    V8_INLINE ~EscapableHandleScope() {}
  
    /**
     * Pushes the value into the previous scope and returns a handle to it.
     * Cannot be called twice.
     */
    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_;
  };
  
  
  /**
   * A simple Maybe type, representing an object which may or may not have a
   * value.
   */
  template<class T>
  struct Maybe {
    Maybe() : has_value(false) {}
    explicit Maybe(T t) : has_value(true), value(t) {}
    Maybe(bool has, T t) : has_value(has), value(t) {}
  
    bool has_value;
    T value;
  };
  
  
  // Convenience wrapper.
  template <class T>
  inline Maybe<T> maybe(T t) {
    return Maybe<T>(t);
  }
  
  
  // --- Special objects ---
  
  
  /**
   * The superclass of values and API object templates.
   */
  class V8_EXPORT Data {
   private:
    Data();
  };
  
  
  /**
   * The origin, within a file, of a script.
   */
  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>())
        : resource_name_(resource_name),
          resource_line_offset_(resource_line_offset),
          resource_column_offset_(resource_column_offset),
          resource_is_shared_cross_origin_(resource_is_shared_cross_origin),
          script_id_(script_id) { }
    V8_INLINE Handle<Value> ResourceName() const;
    V8_INLINE Handle<Integer> ResourceLineOffset() const;
    V8_INLINE Handle<Integer> ResourceColumnOffset() const;
    V8_INLINE Handle<Boolean> ResourceIsSharedCrossOrigin() const;
    V8_INLINE Handle<Integer> ScriptID() const;
   private:
    Handle<Value> resource_name_;
    Handle<Integer> resource_line_offset_;
    Handle<Integer> resource_column_offset_;
    Handle<Boolean> resource_is_shared_cross_origin_;
    Handle<Integer> script_id_;
  };
  
  
  /**
   * A compiled JavaScript script, not yet tied to a Context.
   */
  class V8_EXPORT UnboundScript {
   public:
    /**
     * Binds the script to the currently entered context.
     */
    Local<Script> BindToCurrentContext();
  
    int GetId();
    Handle<Value> GetScriptName();
  
    /**
     * Data read from magic sourceURL comments.
     */
    Handle<Value> GetSourceURL();
    /**
     * Data read from magic sourceMappingURL comments.
     */
    Handle<Value> GetSourceMappingURL();
  
    /**
     * Returns zero based line number of the code_pos location in the script.
     * -1 will be returned if no information available.
     */
    int GetLineNumber(int code_pos);
  
    static const int kNoScriptId = 0;
  };
  
  
  /**
   * A compiled JavaScript script, tied to a Context which was active when the
   * script was compiled.
   */
  class V8_EXPORT Script {
   public:
    /**
     * A shorthand for ScriptCompiler::Compile().
     */
    static Local<Script> Compile(Handle<String> source,
                                 ScriptOrigin* origin = NULL);
  
    // To be decprecated, use the Compile above.
    static Local<Script> Compile(Handle<String> source,
                                 Handle<String> file_name);
  
    /**
     * Runs the script returning the resulting value. It will be run in the
     * context in which it was created (ScriptCompiler::CompileBound or
     * UnboundScript::BindToCurrentContext()).
     */
    Local<Value> Run();
  
    /**
     * Returns the corresponding context-unbound script.
     */
    Local<UnboundScript> GetUnboundScript();
  
    V8_DEPRECATED("Use GetUnboundScript()->GetId()",
                  int GetId()) {
      return GetUnboundScript()->GetId();
    }
  };
  
  
  /**
   * For compiling scripts.
   */
  class V8_EXPORT ScriptCompiler {
   public:
    /**
     * Compilation data that the embedder can cache and pass back to speed up
     * future compilations. The data is produced if the CompilerOptions passed to
     * the compilation functions in ScriptCompiler contains produce_data_to_cache
     * = true. The data to cache can then can be retrieved from
     * UnboundScript.
     */
    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&);
    };
  
    /**
     * Source code which can be then compiled to a UnboundScript or Script.
     */
    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_shared_cross_origin;
  
      // 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;
    };
  
    /**
     * For streaming incomplete script data to V8. The embedder should implement a
     * subclass of this class.
     */
    class ExternalSourceStream {
     public:
      virtual ~ExternalSourceStream() {}
  
      /**
       * V8 calls this to request the next chunk of data from the embedder. This
       * function will be called on a background thread, so it's OK to block and
       * wait for the data, if the embedder doesn't have data yet. Returns the
       * length of the data returned. When the data ends, GetMoreData should
       * return 0. Caller takes ownership of the data.
       *
       * When streaming UTF-8 data, V8 handles multi-byte characters split between
       * two data chunks, but doesn't handle multi-byte characters split between
       * more than two data chunks. The embedder can avoid this problem by always
       * returning at least 2 bytes of data.
       *
       * If the embedder wants to cancel the streaming, they should make the next
       * GetMoreData call return 0. V8 will interpret it as end of data (and most
       * probably, parsing will fail). The streaming task will return as soon as
       * V8 has parsed the data it received so far.
       */
      virtual size_t GetMoreData(const uint8_t** src) = 0;
    };
  
  
    /**
     * Source code which can be streamed into V8 in pieces. It will be parsed
     * while streaming. It can be compiled after the streaming is complete.
     * StreamedSource must be kept alive while the streaming task is ran (see
     * ScriptStreamingTask below).
     */
    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_;
    };
  
    /**
     * A streaming task which the embedder must run on a background thread to
     * stream scripts into V8. Returned by ScriptCompiler::StartStreamingScript.
     */
    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
    };
  
    /**
     * Compiles the specified script (context-independent).
     * Cached data as part of the source object can be optionally produced to be
     * consumed later to speed up compilation of identical source scripts.
     *
     * Note that when producing cached data, the source must point to NULL for
     * cached data. When consuming cached data, the cached data must have been
     * produced by the same version of V8.
     *
     * \param source Script source code.
     * \return Compiled script object (context independent; for running it must be
     *   bound to a context).
     */
    static Local<UnboundScript> CompileUnbound(
        Isolate* isolate, Source* source,
        CompileOptions options = kNoCompileOptions);
  
    /**
     * Compiles the specified script (bound to current context).
     *
     * \param source Script source code.
     * \param pre_data Pre-parsing data, as obtained by ScriptData::PreCompile()
     *   using pre_data speeds compilation if it's done multiple times.
     *   Owned by caller, no references are kept when this function returns.
     * \return Compiled script object, bound to the context that was active
     *   when this function was called. When run it will always use this
     *   context.
     */
    static Local<Script> Compile(
        Isolate* isolate, Source* source,
        CompileOptions options = kNoCompileOptions);
  
    /**
     * Returns a task which streams script data into V8, or NULL if the script
     * cannot be streamed. The user is responsible for running the task on a
     * background thread and deleting it. When ran, the task starts parsing the
     * script, and it will request data from the StreamedSource as needed. When
     * ScriptStreamingTask::Run exits, all data has been streamed and the script
     * can be compiled (see Compile below).
     *
     * This API allows to start the streaming with as little data as possible, and
     * the remaining data (for example, the ScriptOrigin) is passed to Compile.
     */
    static ScriptStreamingTask* StartStreamingScript(
        Isolate* isolate, StreamedSource* source,
        CompileOptions options = kNoCompileOptions);
  
    /**
     * Compiles a streamed script (bound to current context).
     *
     * This can only be called after the streaming has finished
     * (ScriptStreamingTask has been run). V8 doesn't construct the source string
     * during streaming, so the embedder needs to pass the full source here.
     */
    static Local<Script> Compile(Isolate* isolate, StreamedSource* source,
                                 Handle<String> full_source_string,
                                 const ScriptOrigin& origin);
  
    /**
     * Return a version tag for CachedData for the current V8 version & flags.
     *
     * This value is meant only for determining whether a previously generated
     * CachedData instance is still valid; the tag has no other meaing.
     *
     * Background: The data carried by CachedData may depend on the exact
     *   V8 version number or currently compiler flags. This means when
     *   persisting CachedData, the embedder must take care to not pass in
     *   data from another V8 version, or the same version with different
     *   features enabled.
     *
     *   The easiest way to do so is to clear the embedder's cache on any
     *   such change.
     *
     *   Alternatively, this tag can be stored alongside the cached data and
     *   compared when it is being used.
     */
    static uint32_t CachedDataVersionTag();
  };
  
  
  /**
   * An error message.
   */
  class V8_EXPORT Message {
   public:
    Local<String> Get() const;
    Local<String> GetSourceLine() const;
  
    /**
     * Returns the origin for the script from where the function causing the
     * error originates.
     */
    ScriptOrigin GetScriptOrigin() const;
  
    /**
     * Returns the resource name for the script from where the function causing
     * the error originates.
     */
    Handle<Value> GetScriptResourceName() const;
  
    /**
     * Exception stack trace. By default stack traces are not captured for
     * uncaught exceptions. SetCaptureStackTraceForUncaughtExceptions allows
     * to change this option.
     */
    Handle<StackTrace> GetStackTrace() const;
  
    /**
     * Returns the number, 1-based, of the line where the error occurred.
     */
    int GetLineNumber() const;
  
    /**
     * Returns the index within the script of the first character where
     * the error occurred.
     */
    int GetStartPosition() const;
  
    /**
     * Returns the index within the script of the last character where
     * the error occurred.
     */
    int GetEndPosition() const;
  
    /**
     * Returns the index within the line of the first character where
     * the error occurred.
     */
    int GetStartColumn() const;
  
    /**
     * Returns the index within the line of the last character where
     * the error occurred.
     */
    int GetEndColumn() const;
  
    /**
     * Passes on the value set by the embedder when it fed the script from which
     * this Message was generated to V8.
     */
    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;
  };
  
  
  /**
   * Representation of a JavaScript stack trace. The information collected is a
   * snapshot of the execution stack and the information remains valid after
   * execution continues.
   */
  class V8_EXPORT StackTrace {
   public:
    /**
     * Flags that determine what information is placed captured for each
     * StackFrame when grabbing the current stack trace.
     */
    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
    };
  
    /**
     * Returns a StackFrame at a particular index.
     */
    Local<StackFrame> GetFrame(uint32_t index) const;
  
    /**
     * Returns the number of StackFrames.
     */
    int GetFrameCount() const;
  
    /**
     * Returns StackTrace as a v8::Array that contains StackFrame objects.
     */
    Local<Array> AsArray();
  
    /**
     * Grab a snapshot of the current JavaScript execution stack.
     *
     * \param frame_limit The maximum number of stack frames we want to capture.
     * \param options Enumerates the set of things we will capture for each
     *   StackFrame.
     */
    static Local<StackTrace> CurrentStackTrace(
        Isolate* isolate,
        int frame_limit,
        StackTraceOptions options = kOverview);
  };
  
  
  /**
   * A single JavaScript stack frame.
   */
  class V8_EXPORT StackFrame {
   public:
    /**
     * Returns the number, 1-based, of the line for the associate function call.
     * This method will return Message::kNoLineNumberInfo if it is unable to
     * retrieve the line number, or if kLineNumber was not passed as an option
     * when capturing the StackTrace.
     */
    int GetLineNumber() const;
  
    /**
     * Returns the 1-based column offset on the line for the associated function
     * call.
     * This method will return Message::kNoColumnInfo if it is unable to retrieve
     * the column number, or if kColumnOffset was not passed as an option when
     * capturing the StackTrace.
     */
    int GetColumn() const;
  
    /**
     * Returns the id of the script for the function for this StackFrame.
     * This method will return Message::kNoScriptIdInfo if it is unable to
     * retrieve the script id, or if kScriptId was not passed as an option when
     * capturing the StackTrace.
     */
    int GetScriptId() const;
  
    /**
     * Returns the name of the resource that contains the script for the
     * function for this StackFrame.
     */
    Local<String> GetScriptName() const;
  
    /**
     * Returns the name of the resource that contains the script for the
     * function for this StackFrame or sourceURL value if the script name
     * is undefined and its source ends with //# sourceURL=... string or
     * deprecated //@ sourceURL=... string.
     */
    Local<String> GetScriptNameOrSourceURL() const;
  
    /**
     * Returns the name of the function associated with this stack frame.
     */
    Local<String> GetFunctionName() const;
  
    /**
     * Returns whether or not the associated function is compiled via a call to
     * eval().
     */
    bool IsEval() const;
  
    /**
     * Returns whether or not the associated function is called as a
     * constructor via "new".
     */
    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;
  };
  
  
  /**
   * A JSON Parser.
   */
  class V8_EXPORT JSON {
   public:
    /**
     * Tries to parse the string |json_string| and returns it as value if
     * successful.
     *
     * \param json_string The string to parse.
     * \return The corresponding value if successfully parsed.
     */
    static Local<Value> Parse(Local<String> json_string);
  };
  
  
  // --- Value ---
  
  
  /**
   * The superclass of all JavaScript values and objects.
   */
  class V8_EXPORT Value : public Data {
   public:
    /**
     * Returns true if this value is the undefined value.  See ECMA-262
     * 4.3.10.
     */
    V8_INLINE bool IsUndefined() const;
  
    /**
     * Returns true if this value is the null value.  See ECMA-262
     * 4.3.11.
     */
    V8_INLINE bool IsNull() const;
  
     /**
     * Returns true if this value is true.
     */
    bool IsTrue() const;
  
    /**
     * Returns true if this value is false.
     */
    bool IsFalse() const;
  
    /**
     * Returns true if this value is a symbol or a string.
     * This is an experimental feature.
     */
    bool IsName() const;
  
    /**
     * Returns true if this value is an instance of the String type.
     * See ECMA-262 8.4.
     */
    V8_INLINE bool IsString() const;
  
    /**
     * Returns true if this value is a symbol.
     * This is an experimental feature.
     */
    bool IsSymbol() const;
  
    /**
     * Returns true if this value is a function.
     */
    bool IsFunction() const;
  
    /**
     * Returns true if this value is an array.
     */
    bool IsArray() const;
  
    /**
     * Returns true if this value is an object.
     */
    bool IsObject() const;
  
    /**
     * Returns true if this value is boolean.
     */
    bool IsBoolean() const;
  
    /**
     * Returns true if this value is a number.
     */
    bool IsNumber() const;
  
    /**
     * Returns true if this value is external.
     */
    bool IsExternal() const;
  
    /**
     * Returns true if this value is a 32-bit signed integer.
     */
    bool IsInt32() const;
  
    /**
     * Returns true if this value is a 32-bit unsigned integer.
     */
    bool IsUint32() const;
  
    /**
     * Returns true if this value is a Date.
     */
    bool IsDate() const;
  
    /**
     * Returns true if this value is an Arguments object.
     */
    bool IsArgumentsObject() const;
  
    /**
     * Returns true if this value is a Boolean object.
     */
    bool IsBooleanObject() const;
  
    /**
     * Returns true if this value is a Number object.
     */
    bool IsNumberObject() const;
  
    /**
     * Returns true if this value is a String object.
     */
    bool IsStringObject() const;
  
    /**
     * Returns true if this value is a Symbol object.
     * This is an experimental feature.
     */
    bool IsSymbolObject() const;
  
    /**
     * Returns true if this value is a NativeError.
     */
    bool IsNativeError() const;
  
    /**
     * Returns true if this value is a RegExp.
     */
    bool IsRegExp() const;
  
    /**
     * Returns true if this value is a Generator function.
     * This is an experimental feature.
     */
    bool IsGeneratorFunction() const;
  
    /**
     * Returns true if this value is a Generator object (iterator).
     * This is an experimental feature.
     */
    bool IsGeneratorObject() const;
  
    /**
     * Returns true if this value is a Promise.
     * This is an experimental feature.
     */
    bool IsPromise() const;
  
    /**
     * Returns true if this value is a Map.
     * This is an experimental feature.
     */
    bool IsMap() const;
  
    /**
     * Returns true if this value is a Set.
     * This is an experimental feature.
     */
    bool IsSet() const;
  
    /**
     * Returns true if this value is a Map Iterator.
     * This is an experimental feature.
     */
    bool IsMapIterator() const;
  
    /**
     * Returns true if this value is a Set Iterator.
     * This is an experimental feature.
     */
    bool IsSetIterator() const;
  
    /**
     * Returns true if this value is a WeakMap.
     * This is an experimental feature.
     */
    bool IsWeakMap() const;
  
    /**
     * Returns true if this value is a WeakSet.
     * This is an experimental feature.
     */
    bool IsWeakSet() const;
  
    /**
     * Returns true if this value is an ArrayBuffer.
     * This is an experimental feature.
     */
    bool IsArrayBuffer() const;
  
    /**
     * Returns true if this value is an ArrayBufferView.
     * This is an experimental feature.
     */
    bool IsArrayBufferView() const;
  
    /**
     * Returns true if this value is one of TypedArrays.
     * This is an experimental feature.
     */
    bool IsTypedArray() const;
  
    /**
     * Returns true if this value is an Uint8Array.
     * This is an experimental feature.
     */
    bool IsUint8Array() const;
  
    /**
     * Returns true if this value is an Uint8ClampedArray.
     * This is an experimental feature.
     */
    bool IsUint8ClampedArray() const;
  
    /**
     * Returns true if this value is an Int8Array.
     * This is an experimental feature.
     */
    bool IsInt8Array() const;
  
    /**
     * Returns true if this value is an Uint16Array.
     * This is an experimental feature.
     */
    bool IsUint16Array() const;
  
    /**
     * Returns true if this value is an Int16Array.
     * This is an experimental feature.
     */
    bool IsInt16Array() const;
  
    /**
     * Returns true if this value is an Uint32Array.
     * This is an experimental feature.
     */
    bool IsUint32Array() const;
  
    /**
     * Returns true if this value is an Int32Array.
     * This is an experimental feature.
     */
    bool IsInt32Array() const;
  
    /**
     * Returns true if this value is a Float32Array.
     * This is an experimental feature.
     */
    bool IsFloat32Array() const;
  
    /**
     * Returns true if this value is a Float64Array.
     * This is an experimental feature.
     */
    bool IsFloat64Array() const;
  
    /**
     * Returns true if this value is a DataView.
     * This is an experimental feature.
     */
    bool IsDataView() const;
  
    Local<Boolean> ToBoolean(Isolate* isolate) const;
    Local<Number> ToNumber(Isolate* isolate) const;
    Local<String> ToString(Isolate* isolate) const;
    Local<String> ToDetailString(Isolate* isolate) const;
    Local<Object> ToObject(Isolate* isolate) const;
    Local<Integer> ToInteger(Isolate* isolate) const;
    Local<Uint32> ToUint32(Isolate* isolate) const;
    Local<Int32> ToInt32(Isolate* isolate) const;
  
    // TODO(dcarney): deprecate all these.
    inline Local<Boolean> ToBoolean() const;
    inline Local<Number> ToNumber() const;
    inline Local<String> ToString() const;
    inline Local<String> ToDetailString() const;
    inline Local<Object> ToObject() const;
    inline Local<Integer> ToInteger() const;
    inline Local<Uint32> ToUint32() const;
    inline Local<Int32> ToInt32() const;
  
    /**
     * Attempts to convert a string to an array index.
     * Returns an empty handle if the conversion fails.
     */
    Local<Uint32> ToArrayIndex() const;
  
    bool BooleanValue() const;
    double NumberValue() const;
    int64_t IntegerValue() const;
    uint32_t Uint32Value() const;
    int32_t Int32Value() const;
  
    /** JS == */
    bool Equals(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;
  };
  
  
  /**
   * The superclass of primitive values.  See ECMA-262 4.3.2.
   */
  class V8_EXPORT Primitive : public Value { };
  
  
  /**
   * A primitive boolean value (ECMA-262, 4.3.14).  Either the true
   * or false value.
   */
  class V8_EXPORT Boolean : public Primitive {
   public:
    bool Value() const;
    V8_INLINE static Handle<Boolean> New(Isolate* isolate, bool value);
  };
  
  
  /**
   * A superclass for symbols and strings.
   */
  class V8_EXPORT Name : public Primitive {
   public:
    /**
     * Returns the identity hash for this object. The current implementation
     * uses an inline property on the object to store the identity hash.
     *
     * The return value will never be 0. Also, it is not guaranteed to be
     * unique.
     */
    int GetIdentityHash();
  
    V8_INLINE static Name* Cast(v8::Value* obj);
   private:
    static void CheckCast(v8::Value* obj);
  };
  
  
  /**
   * A JavaScript string value (ECMA-262, 4.3.17).
   */
  class V8_EXPORT String : public Name {
   public:
    enum Encoding {
      UNKNOWN_ENCODING = 0x1,
      TWO_BYTE_ENCODING = 0x0,
      ONE_BYTE_ENCODING = 0x4
    };
    /**
     * Returns the number of characters in this string.
     */
    int Length() const;
  
    /**
     * Returns the number of bytes in the UTF-8 encoded
     * representation of this string.
     */
    int Utf8Length() const;
  
    /**
     * Returns whether this string is known to contain only one byte data.
     * Does not read the string.
     * False negatives are possible.
     */
    bool IsOneByte() const;
  
    /**
     * Returns whether this string contain only one byte data.
     * Will read the entire string in some cases.
     */
    bool ContainsOnlyOneByte() const;
  
    /**
     * Write the contents of the string to an external buffer.
     * If no arguments are given, expects the buffer to be large
     * enough to hold the entire string and NULL terminator. Copies
     * the contents of the string and the NULL terminator into the
     * buffer.
     *
     * WriteUtf8 will not write partial UTF-8 sequences, preferring to stop
     * before the end of the buffer.
     *
     * Copies up to length characters into the output buffer.
     * Only null-terminates if there is enough space in the buffer.
     *
     * \param buffer The buffer into which the string will be copied.
     * \param start The starting position within the string at which
     * copying begins.
     * \param length The number of characters to copy from the string.  For
     *    WriteUtf8 the number of bytes in the buffer.
     * \param nchars_ref The number of characters written, can be NULL.
     * \param options Various options that might affect performance of this or
     *    subsequent operations.
     * \return The number of characters copied to the buffer excluding the null
     *    terminator.  For WriteUtf8: The number of bytes copied to the buffer
     *    including the null terminator (if written).
     */
    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;
  
    /**
     * A zero length string.
     */
    V8_INLINE static v8::Local<v8::String> Empty(Isolate* isolate);
  
    /**
     * Returns true if the string is external
     */
    bool IsExternal() const;
  
    /**
     * Returns true if the string is both external and one-byte.
     */
    bool IsExternalOneByte() const;
  
    class V8_EXPORT ExternalStringResourceBase {  // NOLINT
     public:
      virtual ~ExternalStringResourceBase() {}
  
     protected:
      ExternalStringResourceBase() {}
  
      /**
       * Internally V8 will call this Dispose method when the external string
       * resource is no longer needed. The default implementation will use the
       * delete operator. This method can be overridden in subclasses to
       * control how allocated external string resources are disposed.
       */
      virtual void Dispose() { delete this; }
  
     private:
      // Disallow copying and assigning.
      ExternalStringResourceBase(const ExternalStringResourceBase&);
      void operator=(const ExternalStringResourceBase&);
  
      friend class v8::internal::Heap;
    };
  
    /**
     * An ExternalStringResource is a wrapper around a two-byte string
     * buffer that resides outside V8's heap. Implement an
     * ExternalStringResource to manage the life cycle of the underlying
     * buffer.  Note that the string data must be immutable.
     */
    class V8_EXPORT ExternalStringResource
        : public ExternalStringResourceBase {
     public:
      /**
       * Override the destructor to manage the life cycle of the underlying
       * buffer.
       */
      virtual ~ExternalStringResource() {}
  
      /**
       * The string data from the underlying buffer.
       */
      virtual const uint16_t* data() const = 0;
  
      /**
       * The length of the string. That is, the number of two-byte characters.
       */
      virtual size_t length() const = 0;
  
     protected:
      ExternalStringResource() {}
    };
  
    /**
     * An ExternalOneByteStringResource is a wrapper around an one-byte
     * string buffer that resides outside V8's heap. Implement an
     * ExternalOneByteStringResource to manage the life cycle of the
     * underlying buffer.  Note that the string data must be immutable
     * and that the data must be Latin-1 and not UTF-8, which would require
     * special treatment internally in the engine and do not allow efficient
     * indexing.  Use String::New or convert to 16 bit data for non-Latin1.
     */
  
    class V8_EXPORT ExternalOneByteStringResource
        : public ExternalStringResourceBase {
     public:
      /**
       * Override the destructor to manage the life cycle of the underlying
       * buffer.
       */
      virtual ~ExternalOneByteStringResource() {}
      /** The string data from the underlying buffer.*/
      virtual const char* data() const = 0;
      /** The number of Latin-1 characters in the string.*/
      virtual size_t length() const = 0;
     protected:
      ExternalOneByteStringResource() {}
    };
  
    /**
     * If the string is an external string, return the ExternalStringResourceBase
     * regardless of the encoding, otherwise return NULL.  The encoding of the
     * string is returned in encoding_out.
     */
    V8_INLINE ExternalStringResourceBase* GetExternalStringResourceBase(
        Encoding* encoding_out) const;
  
    /**
     * Get the ExternalStringResource for an external string.  Returns
     * NULL if IsExternal() doesn't return true.
     */
    V8_INLINE ExternalStringResource* GetExternalStringResource() const;
  
    /**
     * Get the ExternalOneByteStringResource for an external one-byte string.
     * Returns NULL if IsExternalOneByte() doesn't return true.
     */
    const ExternalOneByteStringResource* GetExternalOneByteStringResource() const;
  
    V8_INLINE static String* Cast(v8::Value* obj);
  
    enum NewStringType {
      kNormalString, kInternalizedString, kUndetectableString
    };
  
    /** Allocates a new string from UTF-8 data.*/
    static Local<String> NewFromUtf8(Isolate* isolate,
                                    const char* data,
                                    NewStringType type = kNormalString,
                                    int length = -1);
  
    /** Allocates a new string from Latin-1 data.*/
    static Local<String> NewFromOneByte(
        Isolate* isolate,
        const uint8_t* data,
        NewStringType type = kNormalString,
        int length = -1);
  
    /** Allocates a new string from UTF-16 data.*/
    static Local<String> NewFromTwoByte(
        Isolate* isolate,
        const uint16_t* data,
        NewStringType type = kNormalString,
        int length = -1);
  
    /**
     * Creates a new string by concatenating the left and the right strings
     * passed in as parameters.
     */
    static Local<String> Concat(Handle<String> left, Handle<String> right);
  
    /**
     * Creates a new external string using the data defined in the given
     * resource. When the external string is no longer live on V8's heap the
     * resource will be disposed by calling its Dispose method. The caller of
     * this function should not otherwise delete or modify the resource. Neither
     * should the underlying buffer be deallocated or modified except through the
     * destructor of the external string resource.
     */
    static Local<String> NewExternal(Isolate* isolate,
                                     ExternalStringResource* resource);
  
    /**
     * Associate an external string resource with this string by transforming it
     * in place so that existing references to this string in the JavaScript heap
     * will use the external string resource. The external string resource's
     * character contents need to be equivalent to this string.
     * Returns true if the string has been changed to be an external string.
     * The string is not modified if the operation fails. See NewExternal for
     * information on the lifetime of the resource.
     */
    bool MakeExternal(ExternalStringResource* resource);
  
    /**
     * Creates a new external string using the one-byte data defined in the given
     * resource. When the external string is no longer live on V8's heap the
     * resource will be disposed by calling its Dispose method. The caller of
     * this function should not otherwise delete or modify the resource. Neither
     * should the underlying buffer be deallocated or modified except through the
     * destructor of the external string resource.
     */
    static Local<String> NewExternal(Isolate* isolate,
                                     ExternalOneByteStringResource* resource);
  
    /**
     * Associate an external string resource with this string by transforming it
     * in place so that existing references to this string in the JavaScript heap
     * will use the external string resource. The external string resource's
     * character contents need to be equivalent to this string.
     * Returns true if the string has been changed to be an external string.
     * The string is not modified if the operation fails. See NewExternal for
     * information on the lifetime of the resource.
     */
    bool MakeExternal(ExternalOneByteStringResource* resource);
  
    /**
     * Returns true if this string can be made external.
     */
    bool CanMakeExternal();
  
    /**
     * Converts an object to a UTF-8-encoded character array.  Useful if
     * you want to print the object.  If conversion to a string fails
     * (e.g. due to an exception in the toString() method of the object)
     * then the length() method returns 0 and the * operator returns
     * NULL.
     */
    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&);
    };
  
    /**
     * Converts an object to a two-byte string.
     * If conversion to a string fails (eg. due to an exception in the toString()
     * method of the object) then the length() method returns 0 and the * operator
     * returns NULL.
     */
    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);
  };
  
  
  /**
   * A JavaScript symbol (ECMA-262 edition 6)
   *
   * This is an experimental feature. Use at your own risk.
   */
  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);
  };
  
  
  /**
   * A private symbol
   *
   * This is an experimental feature. Use at your own risk.
   */
  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();
  };
  
  
  /**
   * A JavaScript number value (ECMA-262, 4.3.20)
   */
  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);
  };
  
  
  /**
   * A JavaScript value representing a signed integer.
   */
  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);
  };
  
  
  /**
   * A JavaScript value representing a 32-bit signed integer.
   */
  class V8_EXPORT Int32 : public Integer {
   public:
    int32_t Value() const;
   private:
    Int32();
  };
  
  
  /**
   * A JavaScript value representing a 32-bit unsigned integer.
   */
  class V8_EXPORT Uint32 : public Integer {
   public:
    uint32_t Value() const;
   private:
    Uint32();
  };
  
  
  enum PropertyAttribute {
    None       = 0,
    ReadOnly   = 1 << 0,
    DontEnum   = 1 << 1,
    DontDelete = 1 << 2
  };
  
  enum ExternalArrayType {
    kExternalInt8Array = 1,
    kExternalUint8Array,
    kExternalInt16Array,
    kExternalUint16Array,
    kExternalInt32Array,
    kExternalUint32Array,
    kExternalFloat32Array,
    kExternalFloat64Array,
    kExternalUint8ClampedArray,
  
    // Legacy constant names
    kExternalByteArray = kExternalInt8Array,
    kExternalUnsignedByteArray = kExternalUint8Array,
    kExternalShortArray = kExternalInt16Array,
    kExternalUnsignedShortArray = kExternalUint16Array,
    kExternalIntArray = kExternalInt32Array,
    kExternalUnsignedIntArray = kExternalUint32Array,
    kExternalFloatArray = kExternalFloat32Array,
    kExternalDoubleArray = kExternalFloat64Array,
    kExternalPixelArray = kExternalUint8ClampedArray
  };
  
  /**
   * Accessor[Getter|Setter] are used as callback functions when
   * setting|getting a particular property. See Object and ObjectTemplate's
   * method SetAccessor.
   */
  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);
  
  
  /**
   * Access control specifications.
   *
   * Some accessors should be accessible across contexts.  These
   * accessors have an explicit access control parameter which specifies
   * the kind of cross-context access that should be allowed.
   *
   * TODO(dcarney): Remove PROHIBITS_OVERWRITING as it is now unused.
   */
  enum AccessControl {
    DEFAULT               = 0,
    ALL_CAN_READ          = 1,
    ALL_CAN_WRITE         = 1 << 1,
    PROHIBITS_OVERWRITING = 1 << 2
  };
  
  
  /**
   * A JavaScript object (ECMA-262, 4.3.3)
   */
  class V8_EXPORT Object : public Value {
   public:
    bool Set(Handle<Value> key, Handle<Value> value);
  
    bool Set(uint32_t index, Handle<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.
    bool ForceSet(Handle<Value> key,
                  Handle<Value> value,
                  PropertyAttribute attribs = None);
  
    Local<Value> Get(Handle<Value> key);
  
    Local<Value> Get(uint32_t index);
  
    /**
     * Gets the property attributes of a property which can be None or
     * any combination of ReadOnly, DontEnum and DontDelete. Returns
     * None when the property doesn't exist.
     */
    PropertyAttribute GetPropertyAttributes(Handle<Value> key);
  
    /**
     * Returns Object.getOwnPropertyDescriptor as per ES5 section 15.2.3.3.
     */
    Local<Value> GetOwnPropertyDescriptor(Local<String> key);
  
    bool Has(Handle<Value> key);
  
    bool Delete(Handle<Value> key);
  
    // Delete a property on this object bypassing interceptors and
    // ignoring dont-delete attributes.
    bool ForceDelete(Handle<Value> key);
  
    bool Has(uint32_t index);
  
    bool Delete(uint32_t index);
  
    bool SetAccessor(Handle<String> name,
                     AccessorGetterCallback getter,
                     AccessorSetterCallback setter = 0,
                     Handle<Value> data = Handle<Value>(),
                     AccessControl settings = DEFAULT,
                     PropertyAttribute attribute = None);
    bool SetAccessor(Handle<Name> name,
                     AccessorNameGetterCallback getter,
                     AccessorNameSetterCallback setter = 0,
                     Handle<Value> data = Handle<Value>(),
                     AccessControl settings = DEFAULT,
                     PropertyAttribute attribute = None);
  
    // This function is not yet stable and should not be used at this time.
    bool SetDeclaredAccessor(Local<Name> name,
                             Local<DeclaredAccessorDescriptor> descriptor,
                             PropertyAttribute attribute = None,
                             AccessControl settings = DEFAULT);
  
    void SetAccessorProperty(Local<Name> name,
                             Local<Function> getter,
                             Handle<Function> setter = Handle<Function>(),
                             PropertyAttribute attribute = None,
                             AccessControl settings = DEFAULT);
  
    /**
     * Functionality for private properties.
     * This is an experimental feature, use at your own risk.
     * Note: Private properties are inherited. Do not rely on this, since it may
     * change.
     */
    bool HasPrivate(Handle<Private> key);
    bool SetPrivate(Handle<Private> key, Handle<Value> value);
    bool DeletePrivate(Handle<Private> key);
    Local<Value> GetPrivate(Handle<Private> key);
  
    /**
     * Returns an array containing the names of the enumerable properties
     * of this object, including properties from prototype objects.  The
     * array returned by this method contains the same values as would
     * be enumerated by a for-in statement over this object.
     */
    Local<Array> GetPropertyNames();
  
    /**
     * This function has the same functionality as GetPropertyNames but
     * the returned array doesn't contain the names of properties from
     * prototype objects.
     */
    Local<Array> GetOwnPropertyNames();
  
    /**
     * Get the prototype object.  This does not skip objects marked to
     * be skipped by __proto__ and it does not consult the security
     * handler.
     */
    Local<Value> GetPrototype();
  
    /**
     * Set the prototype object.  This does not skip objects marked to
     * be skipped by __proto__ and it does not consult the security
     * handler.
     */
    bool SetPrototype(Handle<Value> prototype);
  
    /**
     * Finds an instance of the given function template in the prototype
     * chain.
     */
    Local<Object> FindInstanceInPrototypeChain(Handle<FunctionTemplate> tmpl);
  
    /**
     * Call builtin Object.prototype.toString on this object.
     * This is different from Value::ToString() that may call
     * user-defined toString function. This one does not.
     */
    Local<String> ObjectProtoToString();
  
    /**
     * Returns the name of the function invoked as a constructor for this object.
     */
    Local<String> GetConstructorName();
  
    /** Gets the number of internal fields for this Object. */
    int InternalFieldCount();
  
    static const int kNoInternalFieldIndex = -1;
  
    /** Same as above, but works for Persistents */
    V8_INLINE static int InternalFieldCount(
        const PersistentBase<Object>& object) {
      return object.val_->InternalFieldCount();
    }
  
    /** Gets the value from an internal field. */
    V8_INLINE Local<Value> GetInternalField(int index);
  
    /** Sets the value in an internal field. */
    void SetInternalField(int index, Handle<Value> value);
  
    /**
     * Gets a 2-byte-aligned native pointer from an internal field. This field
     * must have been set by SetAlignedPointerInInternalField, everything else
     * leads to undefined behavior.
     */
    V8_INLINE void* GetAlignedPointerFromInternalField(int index);
  
    /** Same as above, but works for Persistents */
    V8_INLINE static void* GetAlignedPointerFromInternalField(
        const PersistentBase<Object>& object, int index) {
      return object.val_->GetAlignedPointerFromInternalField(index);
    }
  
    /**
     * Sets a 2-byte-aligned native pointer in an internal field. To retrieve such
     * a field, GetAlignedPointerFromInternalField must be used, everything else
     * leads to undefined behavior.
     */
    void SetAlignedPointerInInternalField(int index, void* value);
  
    // Testers for local properties.
    bool HasOwnProperty(Handle<String> key);
    bool HasRealNamedProperty(Handle<String> key);
    bool HasRealIndexedProperty(uint32_t index);
    bool HasRealNamedCallbackProperty(Handle<String> key);
  
    /**
     * If result.IsEmpty() no real property was located in the prototype chain.
     * This means interceptors in the prototype chain are not called.
     */
    Local<Value> GetRealNamedPropertyInPrototypeChain(Handle<String> key);
  
    /**
     * If result.IsEmpty() no real property was located on the object or
     * in the prototype chain.
     * This means interceptors in the prototype chain are not called.
     */
    Local<Value> GetRealNamedProperty(Handle<String> key);
  
    /** Tests for a named lookup interceptor.*/
    bool HasNamedLookupInterceptor();
  
    /** Tests for an index lookup interceptor.*/
    bool HasIndexedLookupInterceptor();
  
    /**
     * Turns on access check on the object if the object is an instance of
     * a template that has access check callbacks. If an object has no
     * access check info, the object cannot be accessed by anyone.
     */
    void TurnOnAccessCheck();
  
    /**
     * Returns the identity hash for this object. The current implementation
     * uses a hidden property on the object to store the identity hash.
     *
     * The return value will never be 0. Also, it is not guaranteed to be
     * unique.
     */
    int GetIdentityHash();
  
    /**
     * Access hidden properties on JavaScript objects. These properties are
     * hidden from the executing JavaScript and only accessible through the V8
     * C++ API. Hidden properties introduced by V8 internally (for example the
     * identity hash) are prefixed with "v8::".
     */
    bool SetHiddenValue(Handle<String> key, Handle<Value> value);
    Local<Value> GetHiddenValue(Handle<String> key);
    bool DeleteHiddenValue(Handle<String> key);
  
    /**
     * Clone this object with a fast but shallow copy.  Values will point
     * to the same values as the original object.
     */
    Local<Object> Clone();
  
    /**
     * Returns the context in which the object was created.
     */
    Local<Context> CreationContext();
  
    /**
     * Set the backing store of the indexed properties to be managed by the
     * embedding layer. Access to the indexed properties will follow the rules
     * spelled out in CanvasPixelArray.
     * Note: The embedding program still owns the data and needs to ensure that
     *       the backing store is preserved while V8 has a reference.
     */
    void SetIndexedPropertiesToPixelData(uint8_t* data, int length);
    bool HasIndexedPropertiesInPixelData();
    uint8_t* GetIndexedPropertiesPixelData();
    int GetIndexedPropertiesPixelDataLength();
  
    /**
     * Set the backing store of the indexed properties to be managed by the
     * embedding layer. Access to the indexed properties will follow the rules
     * spelled out for the CanvasArray subtypes in the WebGL specification.
     * Note: The embedding program still owns the data and needs to ensure that
     *       the backing store is preserved while V8 has a reference.
     */
    void SetIndexedPropertiesToExternalArrayData(void* data,
                                                 ExternalArrayType array_type,
                                                 int number_of_elements);
    bool HasIndexedPropertiesInExternalArrayData();
    void* GetIndexedPropertiesExternalArrayData();
    ExternalArrayType GetIndexedPropertiesExternalArrayDataType();
    int GetIndexedPropertiesExternalArrayDataLength();
  
    /**
     * Checks whether a callback is set by the
     * ObjectTemplate::SetCallAsFunctionHandler method.
     * When an Object is callable this method returns true.
     */
    bool IsCallable();
  
    /**
     * Call an Object as a function if a callback is set by the
     * ObjectTemplate::SetCallAsFunctionHandler method.
     */
    Local<Value> CallAsFunction(Handle<Value> recv,
                                int argc,
                                Handle<Value> argv[]);
  
    /**
     * Call an Object as a constructor if a callback is set by the
     * ObjectTemplate::SetCallAsFunctionHandler method.
     * Note: This method behaves like the Function::NewInstance method.
     */
    Local<Value> CallAsConstructor(int argc, Handle<Value> argv[]);
  
    /**
     * Return the isolate to which the Object belongs to.
     */
    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);
  };
  
  
  /**
   * An instance of the built-in array constructor (ECMA-262, 15.4.2).
   */
  class V8_EXPORT Array : public Object {
   public:
    uint32_t Length() const;
  
    /**
     * Clones an element at index |index|.  Returns an empty
     * handle if cloning fails (for any reason).
     */
    Local<Object> CloneElementAt(uint32_t index);
  
    /**
     * Creates a JavaScript array with the given length. If the length
     * is negative the returned array will have length 0.
     */
    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 PersistentValueMap;
    V8_INLINE void SetInternal(internal::Object* value) { *value_ = value; }
    V8_INLINE internal::Object* GetDefaultValue();
    V8_INLINE explicit ReturnValue(internal::Object** slot);
    internal::Object** value_;
  };
  
  
  /**
   * The argument information given to function call callbacks.  This
   * class provides access to information about the context of the call,
   * including the receiver, the number and values of arguments, and
   * the holder of the function.
   */
  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_;
    bool is_construct_call_;
  };
  
  
  /**
   * The information passed to a property callback about the context
   * of the property access.
   */
  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);
  
  
  /**
   * A JavaScript function object (ECMA-262, 15.3).
   */
  class V8_EXPORT Function : public Object {
   public:
    /**
     * Create a function in the current execution context
     * for a given FunctionCallback.
     */
    static Local<Function> New(Isolate* isolate,
                               FunctionCallback callback,
                               Local<Value> data = Local<Value>(),
                               int length = 0);
  
    Local<Object> NewInstance() const;
    Local<Object> NewInstance(int argc, Handle<Value> argv[]) const;
    Local<Value> Call(Handle<Value> recv, int argc, Handle<Value> argv[]);
    void SetName(Handle<String> name);
    Handle<Value> GetName() const;
  
    /**
     * Name inferred from variable or property assignment of this function.
     * Used to facilitate debugging and profiling of JavaScript code written
     * in an OO style, where many functions are anonymous but are assigned
     * to object properties.
     */
    Handle<Value> GetInferredName() const;
  
    /**
     * User-defined name assigned to the "displayName" property of this function.
     * Used to facilitate debugging and profiling of JavaScript code.
     */
    Handle<Value> GetDisplayName() const;
  
    /**
     * Returns zero based line number of function body and
     * kLineOffsetNotFound if no information available.
     */
    int GetScriptLineNumber() const;
    /**
     * Returns zero based column number of function body and
     * kLineOffsetNotFound if no information available.
     */
    int GetScriptColumnNumber() const;
  
    /**
     * Tells whether this function is builtin.
     */
    bool IsBuiltin() const;
  
    /**
     * Returns scriptId.
     */
    int ScriptId() const;
  
    /**
     * Returns the original function if this function is bound, else returns
     * v8::Undefined.
     */
    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);
  };
  
  
  /**
   * An instance of the built-in Promise constructor (ES6 draft).
   * This API is experimental. Only works with --harmony flag.
   */
  class V8_EXPORT Promise : public Object {
   public:
    class V8_EXPORT Resolver : public Object {
     public:
      /**
       * Create a new resolver, along with an associated promise in pending state.
       */
      static Local<Resolver> New(Isolate* isolate);
  
      /**
       * Extract the associated promise.
       */
      Local<Promise> GetPromise();
  
      /**
       * Resolve/reject the associated promise with a given value.
       * Ignored if the promise is no longer pending.
       */
      void Resolve(Handle<Value> value);
      void Reject(Handle<Value> value);
  
      V8_INLINE static Resolver* Cast(Value* obj);
  
     private:
      Resolver();
      static void CheckCast(Value* obj);
    };
  
    /**
     * Register a resolution/rejection handler with a promise.
     * The handler is given the respective resolution/rejection value as
     * an argument. If the promise is already resolved/rejected, the handler is
     * invoked at the end of turn.
     */
    Local<Promise> Chain(Handle<Function> handler);
    Local<Promise> Catch(Handle<Function> handler);
    Local<Promise> Then(Handle<Function> handler);
  
    /**
     * Returns true if the promise has at least one derived promise, and
     * therefore resolve/reject handlers (including default 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
  
  /**
   * An instance of the built-in ArrayBuffer constructor (ES6 draft 15.13.5).
   * This API is experimental and may change significantly.
   */
  class V8_EXPORT ArrayBuffer : public Object {
   public:
    /**
     * Allocator that V8 uses to allocate |ArrayBuffer|'s memory.
     * The allocator is a global V8 setting. It should be set with
     * V8::SetArrayBufferAllocator prior to creation of a first ArrayBuffer.
     *
     * This API is experimental and may change significantly.
     */
    class V8_EXPORT Allocator { // NOLINT
     public:
      virtual ~Allocator() {}
  
      /**
       * Allocate |length| bytes. Return NULL if allocation is not successful.
       * Memory should be initialized to zeroes.
       */
      virtual void* Allocate(size_t length) = 0;
  
      /**
       * Allocate |length| bytes. Return NULL if allocation is not successful.
       * Memory does not have to be initialized.
       */
      virtual void* AllocateUninitialized(size_t length) = 0;
      /**
       * Free the memory block of size |length|, pointed to by |data|.
       * That memory is guaranteed to be previously allocated by |Allocate|.
       */
      virtual void Free(void* data, size_t length) = 0;
    };
  
    /**
     * The contents of an |ArrayBuffer|. Externalization of |ArrayBuffer|
     * returns an instance of this class, populated, with a pointer to data
     * and byte length.
     *
     * The Data pointer of ArrayBuffer::Contents is always allocated with
     * Allocator::Allocate that is set with V8::SetArrayBufferAllocator.
     *
     * This API is experimental and may change significantly.
     */
    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;
    };
  
  
    /**
     * Data length in bytes.
     */
    size_t ByteLength() const;
  
    /**
     * Create a new ArrayBuffer. Allocate |byte_length| bytes.
     * Allocated memory will be owned by a created ArrayBuffer and
     * will be deallocated when it is garbage-collected,
     * unless the object is externalized.
     */
    static Local<ArrayBuffer> New(Isolate* isolate, size_t byte_length);
  
    /**
     * Create a new ArrayBuffer over an existing memory block.
     * The created array buffer is immediately in externalized state.
     * The memory block will not be reclaimed when a created ArrayBuffer
     * is garbage-collected.
     */
    static Local<ArrayBuffer> New(Isolate* isolate, void* data,
                                  size_t byte_length);
  
    /**
     * Returns true if ArrayBuffer is extrenalized, that is, does not
     * own its memory block.
     */
    bool IsExternal() const;
  
    /**
     * Returns true if this ArrayBuffer may be neutered.
     */
    bool IsNeuterable() const;
  
    /**
     * Neuters this ArrayBuffer and all its views (typed arrays).
     * Neutering sets the byte length of the buffer and all typed arrays to zero,
     * preventing JavaScript from ever accessing underlying backing store.
     * ArrayBuffer should have been externalized and must be neuterable.
     */
    void Neuter();
  
    /**
     * Make this ArrayBuffer external. The pointer to underlying memory block
     * and byte length are returned as |Contents| structure. After ArrayBuffer
     * had been etxrenalized, it does no longer owns the memory block. The caller
     * should take steps to free memory when it is no longer needed.
     *
     * The memory block is guaranteed to be allocated with |Allocator::Allocate|
     * that has been set with V8::SetArrayBufferAllocator.
     */
    Contents Externalize();
  
    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
  
  
  /**
   * A base class for an instance of one of "views" over ArrayBuffer,
   * including TypedArrays and DataView (ES6 draft 15.13).
   *
   * This API is experimental and may change significantly.
   */
  class V8_EXPORT ArrayBufferView : public Object {
   public:
    /**
     * Returns underlying ArrayBuffer.
     */
    Local<ArrayBuffer> Buffer();
    /**
     * Byte offset in |Buffer|.
     */
    size_t ByteOffset();
    /**
     * Size of a view in bytes.
     */
    size_t ByteLength();
  
    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);
  };
  
  
  /**
   * A base class for an instance of TypedArray series of constructors
   * (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  class V8_EXPORT TypedArray : public ArrayBufferView {
   public:
    /**
     * Number of elements in this typed array
     * (e.g. for Int16Array, |ByteLength|/2).
     */
    size_t Length();
  
    V8_INLINE static TypedArray* Cast(Value* obj);
  
   private:
    TypedArray();
    static void CheckCast(Value* obj);
  };
  
  
  /**
   * An instance of Uint8Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Uint8ClampedArray constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  /**
   * An instance of Int8Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Uint16Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Int16Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Uint32Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Int32Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Float32Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of Float64Array constructor (ES6 draft 15.13.6).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of DataView constructor (ES6 draft 15.13.7).
   * This API is experimental and may change significantly.
   */
  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);
  };
  
  
  /**
   * An instance of the built-in Date constructor (ECMA-262, 15.9).
   */
  class V8_EXPORT Date : public Object {
   public:
    static Local<Value> New(Isolate* isolate, double time);
  
    /**
     * A specialization of Value::NumberValue that is more efficient
     * because we know the structure of this object.
     */
    double ValueOf() const;
  
    V8_INLINE static Date* Cast(v8::Value* obj);
  
    /**
     * Notification that the embedder has changed the time zone,
     * daylight savings time, or other date / time configuration
     * parameters.  V8 keeps a cache of various values used for
     * date / time computation.  This notification will reset
     * those cached values for the current context so that date /
     * time configuration changes would be reflected in the Date
     * object.
     *
     * This API should not be called more than needed as it will
     * negatively impact the performance of date operations.
     */
    static void DateTimeConfigurationChangeNotification(Isolate* isolate);
  
   private:
    static void CheckCast(v8::Value* obj);
  };
  
  
  /**
   * A Number object (ECMA-262, 4.3.21).
   */
  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);
  };
  
  
  /**
   * A Boolean object (ECMA-262, 4.3.15).
   */
  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);
  };
  
  
  /**
   * A String object (ECMA-262, 4.3.18).
   */
  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);
  };
  
  
  /**
   * A Symbol object (ECMA-262 edition 6).
   *
   * This is an experimental feature. Use at your own risk.
   */
  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);
  };
  
  
  /**
   * An instance of the built-in RegExp constructor (ECMA-262, 15.10).
   */
  class V8_EXPORT RegExp : public Object {
   public:
    /**
     * Regular expression flag bits. They can be or'ed to enable a set
     * of flags.
     */
    enum Flags {
      kNone = 0,
      kGlobal = 1,
      kIgnoreCase = 2,
      kMultiline = 4
    };
  
    /**
     * Creates a regular expression from the given pattern string and
     * the flags bit field. May throw a JavaScript exception as
     * described in ECMA-262, 15.10.4.1.
     *
     * For example,
     *   RegExp::New(v8::String::New("foo"),
     *               static_cast<RegExp::Flags>(kGlobal | kMultiline))
     * is equivalent to evaluating "/foo/gm".
     */
    static Local<RegExp> New(Handle<String> pattern, Flags flags);
  
    /**
     * Returns the value of the source property: a string representing
     * the regular expression.
     */
    Local<String> GetSource() const;
  
    /**
     * Returns the flags bit field.
     */
    Flags GetFlags() const;
  
    V8_INLINE static RegExp* Cast(v8::Value* obj);
  
   private:
    static void CheckCast(v8::Value* obj);
  };
  
  
  /**
   * A JavaScript value that wraps a C++ void*. This type of value is mainly used
   * to associate C++ data structures with JavaScript objects.
   */
  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 ---
  
  
  /**
   * The superclass of object and function templates.
   */
  class V8_EXPORT Template : public Data {
   public:
    /** Adds a property to each instance created by this template.*/
    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);
  
    /**
     * Whenever the property with the given name is accessed on objects
     * created from this Template the getter and setter callbacks
     * are called instead of getting and setting the property directly
     * on the JavaScript object.
     *
     * \param name The name of the property for which an accessor is added.
     * \param getter The callback to invoke when getting the property.
     * \param setter The callback to invoke when setting the property.
     * \param data A piece of data that will be passed to the getter and setter
     *   callbacks whenever they are invoked.
     * \param settings Access control settings for the accessor. This is a bit
     *   field consisting of one of more of
     *   DEFAULT = 0, ALL_CAN_READ = 1, or ALL_CAN_WRITE = 2.
     *   The default is to not allow cross-context access.
     *   ALL_CAN_READ means that all cross-context reads are allowed.
     *   ALL_CAN_WRITE means that all cross-context writes are allowed.
     *   The combination ALL_CAN_READ | ALL_CAN_WRITE can be used to allow all
     *   cross-context access.
     * \param attribute The attributes of the property for which an accessor
     *   is added.
     * \param signature The signature describes valid receivers for the accessor
     *   and is used to perform implicit instance checks against them. If the
     *   receiver is incompatible (i.e. is not an instance of the constructor as
     *   defined by FunctionTemplate::HasInstance()), an implicit TypeError is
     *   thrown and no callback is invoked.
     */
    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);
  
    // This function is not yet stable and should not be used at this time.
    bool SetDeclaredAccessor(Local<Name> name,
                             Local<DeclaredAccessorDescriptor> descriptor,
                             PropertyAttribute attribute = None,
                             Local<AccessorSignature> signature =
                                 Local<AccessorSignature>(),
                             AccessControl settings = DEFAULT);
  
   private:
    Template();
  
    friend class ObjectTemplate;
    friend class FunctionTemplate;
  };
  
  
  /**
   * NamedProperty[Getter|Setter] are used as interceptors on object.
   * See ObjectTemplate::SetNamedPropertyHandler.
   */
  typedef void (*NamedPropertyGetterCallback)(
      Local<String> property,
      const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns the value if the setter intercepts the request.
   * Otherwise, returns an empty handle.
   */
  typedef void (*NamedPropertySetterCallback)(
      Local<String> property,
      Local<Value> value,
      const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns a non-empty handle if the interceptor intercepts the request.
   * The result is an integer encoding property attributes (like v8::None,
   * v8::DontEnum, etc.)
   */
  typedef void (*NamedPropertyQueryCallback)(
      Local<String> property,
      const PropertyCallbackInfo<Integer>& info);
  
  
  /**
   * Returns a non-empty handle if the deleter intercepts the request.
   * The return value is true if the property could be deleted and false
   * otherwise.
   */
  typedef void (*NamedPropertyDeleterCallback)(
      Local<String> property,
      const PropertyCallbackInfo<Boolean>& info);
  
  
  /**
   * Returns an array containing the names of the properties the named
   * property getter intercepts.
   */
  typedef void (*NamedPropertyEnumeratorCallback)(
      const PropertyCallbackInfo<Array>& info);
  
  
  // TODO(dcarney): Deprecate and remove previous typedefs, and replace
  // GenericNamedPropertyFooCallback with just NamedPropertyFooCallback.
  /**
   * GenericNamedProperty[Getter|Setter] are used as interceptors on object.
   * See ObjectTemplate::SetNamedPropertyHandler.
   */
  typedef void (*GenericNamedPropertyGetterCallback)(
      Local<Name> property, const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns the value if the setter intercepts the request.
   * Otherwise, returns an empty handle.
   */
  typedef void (*GenericNamedPropertySetterCallback)(
      Local<Name> property, Local<Value> value,
      const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns a non-empty handle if the interceptor intercepts the request.
   * The result is an integer encoding property attributes (like v8::None,
   * v8::DontEnum, etc.)
   */
  typedef void (*GenericNamedPropertyQueryCallback)(
      Local<Name> property, const PropertyCallbackInfo<Integer>& info);
  
  
  /**
   * Returns a non-empty handle if the deleter intercepts the request.
   * The return value is true if the property could be deleted and false
   * otherwise.
   */
  typedef void (*GenericNamedPropertyDeleterCallback)(
      Local<Name> property, const PropertyCallbackInfo<Boolean>& info);
  
  
  /**
   * Returns an array containing the names of the properties the named
   * property getter intercepts.
   */
  typedef void (*GenericNamedPropertyEnumeratorCallback)(
      const PropertyCallbackInfo<Array>& info);
  
  
  /**
   * Returns the value of the property if the getter intercepts the
   * request.  Otherwise, returns an empty handle.
   */
  typedef void (*IndexedPropertyGetterCallback)(
      uint32_t index,
      const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns the value if the setter intercepts the request.
   * Otherwise, returns an empty handle.
   */
  typedef void (*IndexedPropertySetterCallback)(
      uint32_t index,
      Local<Value> value,
      const PropertyCallbackInfo<Value>& info);
  
  
  /**
   * Returns a non-empty handle if the interceptor intercepts the request.
   * The result is an integer encoding property attributes.
   */
  typedef void (*IndexedPropertyQueryCallback)(
      uint32_t index,
      const PropertyCallbackInfo<Integer>& info);
  
  
  /**
   * Returns a non-empty handle if the deleter intercepts the request.
   * The return value is true if the property could be deleted and false
   * otherwise.
   */
  typedef void (*IndexedPropertyDeleterCallback)(
      uint32_t index,
      const PropertyCallbackInfo<Boolean>& info);
  
  
  /**
   * Returns an array containing the indices of the properties the
   * indexed property getter intercepts.
   */
  typedef void (*IndexedPropertyEnumeratorCallback)(
      const PropertyCallbackInfo<Array>& info);
  
  
  /**
   * Access type specification.
   */
  enum AccessType {
    ACCESS_GET,
    ACCESS_SET,
    ACCESS_HAS,
    ACCESS_DELETE,
    ACCESS_KEYS
  };
  
  
  /**
   * Returns true if cross-context access should be allowed to the named
   * property with the given key on the host object.
   */
  typedef bool (*NamedSecurityCallback)(Local<Object> host,
                                        Local<Value> key,
                                        AccessType type,
                                        Local<Value> data);
  
  
  /**
   * Returns true if cross-context access should be allowed to the indexed
   * property with the given index on the host object.
   */
  typedef bool (*IndexedSecurityCallback)(Local<Object> host,
                                          uint32_t index,
                                          AccessType type,
                                          Local<Value> data);
  
  
  /**
   * A FunctionTemplate is used to create functions at runtime. There
   * can only be one function created from a FunctionTemplate in a
   * context.  The lifetime of the created function is equal to the
   * lifetime of the context.  So in case the embedder needs to create
   * temporary functions that can be collected using Scripts is
   * preferred.
   *
   * A FunctionTemplate can have properties, these properties are added to the
   * function object when it is created.
   *
   * A FunctionTemplate has a corresponding instance template which is
   * used to create object instances when the function is used as a
   * constructor. Properties added to the instance template are added to
   * each object instance.
   *
   * A FunctionTemplate can have a prototype template. The prototype template
   * is used to create the prototype object of the function.
   *
   * The following example shows how to use a FunctionTemplate:
   *
   * \code
   *    v8::Local<v8::FunctionTemplate> t = v8::FunctionTemplate::New();
   *    t->Set("func_property", v8::Number::New(1));
   *
   *    v8::Local<v8::Template> proto_t = t->PrototypeTemplate();
   *    proto_t->Set("proto_method", v8::FunctionTemplate::New(InvokeCallback));
   *    proto_t->Set("proto_const", v8::Number::New(2));
   *
   *    v8::Local<v8::ObjectTemplate> instance_t = t->InstanceTemplate();
   *    instance_t->SetAccessor("instance_accessor", InstanceAccessorCallback);
   *    instance_t->SetNamedPropertyHandler(PropertyHandlerCallback, ...);
   *    instance_t->Set("instance_property", Number::New(3));
   *
   *    v8::Local<v8::Function> function = t->GetFunction();
   *    v8::Local<v8::Object> instance = function->NewInstance();
   * \endcode
   *
   * Let's use "function" as the JS variable name of the function object
   * and "instance" for the instance object created above.  The function
   * and the instance will have the following properties:
   *
   * \code
   *   func_property in function == true;
   *   function.func_property == 1;
   *
   *   function.prototype.proto_method() invokes 'InvokeCallback'
   *   function.prototype.proto_const == 2;
   *
   *   instance instanceof function == true;
   *   instance.instance_accessor calls 'InstanceAccessorCallback'
   *   instance.instance_property == 3;
   * \endcode
   *
   * A FunctionTemplate can inherit from another one by calling the
   * FunctionTemplate::Inherit method.  The following graph illustrates
   * the semantics of inheritance:
   *
   * \code
   *   FunctionTemplate Parent  -> Parent() . prototype -> { }
   *     ^                                                  ^
   *     | Inherit(Parent)                                  | .__proto__
   *     |                                                  |
   *   FunctionTemplate Child   -> Child()  . prototype -> { }
   * \endcode
   *
   * A FunctionTemplate 'Child' inherits from 'Parent', the prototype
   * object of the Child() function has __proto__ pointing to the
   * Parent() function's prototype object. An instance of the Child
   * function has all properties on Parent's instance templates.
   *
   * Let Parent be the FunctionTemplate initialized in the previous
   * section and create a Child FunctionTemplate by:
   *
   * \code
   *   Local<FunctionTemplate> parent = t;
   *   Local<FunctionTemplate> child = FunctionTemplate::New();
   *   child->Inherit(parent);
   *
   *   Local<Function> child_function = child->GetFunction();
   *   Local<Object> child_instance = child_function->NewInstance();
   * \endcode
   *
   * The Child function and Child instance will have the following
   * properties:
   *
   * \code
   *   child_func.prototype.__proto__ == function.prototype;
   *   child_instance.instance_accessor calls 'InstanceAccessorCallback'
   *   child_instance.instance_property == 3;
   * \endcode
   */
  class V8_EXPORT FunctionTemplate : public Template {
   public:
    /** Creates a function template.*/
    static Local<FunctionTemplate> New(
        Isolate* isolate,
        FunctionCallback callback = 0,
        Handle<Value> data = Handle<Value>(),
        Handle<Signature> signature = Handle<Signature>(),
        int length = 0);
  
    /** Returns the unique function instance in the current execution context.*/
    Local<Function> GetFunction();
  
    /**
     * Set the call-handler callback for a FunctionTemplate.  This
     * callback is called whenever the function created from this
     * FunctionTemplate is called.
     */
    void SetCallHandler(FunctionCallback callback,
                        Handle<Value> data = Handle<Value>());
  
    /** Set the predefined length property for the FunctionTemplate. */
    void SetLength(int length);
  
    /** Get the InstanceTemplate. */
    Local<ObjectTemplate> InstanceTemplate();
  
    /** Causes the function template to inherit from a parent function template.*/
    void Inherit(Handle<FunctionTemplate> parent);
  
    /**
     * A PrototypeTemplate is the template used to create the prototype object
     * of the function created by this template.
     */
    Local<ObjectTemplate> PrototypeTemplate();
  
    /**
     * Set the class name of the FunctionTemplate.  This is used for
     * printing objects created with the function created from the
     * FunctionTemplate as its constructor.
     */
    void SetClassName(Handle<String> name);
  
    /**
     * Determines whether the __proto__ accessor ignores instances of
     * the function template.  If instances of the function template are
     * ignored, __proto__ skips all instances and instead returns the
     * next object in the prototype chain.
     *
     * Call with a value of true to make the __proto__ accessor ignore
     * instances of the function template.  Call with a value of false
     * to make the __proto__ accessor not ignore instances of the
     * function template.  By default, instances of a function template
     * are not ignored.
     */
    void SetHiddenPrototype(bool value);
  
    /**
     * Sets the ReadOnly flag in the attributes of the 'prototype' property
     * of functions created from this FunctionTemplate to true.
     */
    void ReadOnlyPrototype();
  
    /**
     * Removes the prototype property from functions created from this
     * FunctionTemplate.
     */
    void RemovePrototype();
  
    /**
     * Returns true if the given object is an instance of this function
     * template.
     */
    bool HasInstance(Handle<Value> object);
  
   private:
    FunctionTemplate();
    friend class Context;
    friend class ObjectTemplate;
  };
  
  
  enum class PropertyHandlerFlags { kNone = 0, kAllCanRead = 1 };
  
  
  struct NamedPropertyHandlerConfiguration {
    NamedPropertyHandlerConfiguration(
        /** Note: getter is required **/
        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(
        /** Note: getter is required **/
        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;
  };
  
  
  /**
   * An ObjectTemplate is used to create objects at runtime.
   *
   * Properties added to an ObjectTemplate are added to each object
   * created from the ObjectTemplate.
   */
  class V8_EXPORT ObjectTemplate : public Template {
   public:
    /** Creates an ObjectTemplate. */
    static Local<ObjectTemplate> New(Isolate* isolate);
    // Will be deprecated soon.
    static Local<ObjectTemplate> New();
  
    /** Creates a new instance of this template.*/
    Local<Object> NewInstance();
  
    /**
     * Sets an accessor on the object template.
     *
     * Whenever the property with the given name is accessed on objects
     * created from this ObjectTemplate the getter and setter callbacks
     * are called instead of getting and setting the property directly
     * on the JavaScript object.
     *
     * \param name The name of the property for which an accessor is added.
     * \param getter The callback to invoke when getting the property.
     * \param setter The callback to invoke when setting the property.
     * \param data A piece of data that will be passed to the getter and setter
     *   callbacks whenever they are invoked.
     * \param settings Access control settings for the accessor. This is a bit
     *   field consisting of one of more of
     *   DEFAULT = 0, ALL_CAN_READ = 1, or ALL_CAN_WRITE = 2.
     *   The default is to not allow cross-context access.
     *   ALL_CAN_READ means that all cross-context reads are allowed.
     *   ALL_CAN_WRITE means that all cross-context writes are allowed.
     *   The combination ALL_CAN_READ | ALL_CAN_WRITE can be used to allow all
     *   cross-context access.
     * \param attribute The attributes of the property for which an accessor
     *   is added.
     * \param signature The signature describes valid receivers for the accessor
     *   and is used to perform implicit instance checks against them. If the
     *   receiver is incompatible (i.e. is not an instance of the constructor as
     *   defined by FunctionTemplate::HasInstance()), an implicit TypeError is
     *   thrown and no callback is invoked.
     */
    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>());
  
    /**
     * Sets a named property handler on the object template.
     *
     * Whenever a property whose name is a string is accessed on objects created
     * from this object template, the provided callback is invoked instead of
     * accessing the property directly on the JavaScript object.
     *
     * Note that new code should use the second version that can intercept
     * symbol-named properties as well as string-named properties.
     *
     * \param getter The callback to invoke when getting a property.
     * \param setter The callback to invoke when setting a property.
     * \param query The callback to invoke to check if a property is present,
     *   and if present, get its attributes.
     * \param deleter The callback to invoke when deleting a property.
     * \param enumerator The callback to invoke to enumerate all the named
     *   properties of an object.
     * \param data A piece of data that will be passed to the callbacks
     *   whenever they are invoked.
     */
    // 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);
  
    /**
     * Sets an indexed property handler on the object template.
     *
     * Whenever an indexed property is accessed on objects created from
     * this object template, the provided callback is invoked instead of
     * accessing the property directly on the JavaScript object.
     *
     * \param getter The callback to invoke when getting a property.
     * \param setter The callback to invoke when setting a property.
     * \param query The callback to invoke to check if an object has a property.
     * \param deleter The callback to invoke when deleting a property.
     * \param enumerator The callback to invoke to enumerate all the indexed
     *   properties of an object.
     * \param data A piece of data that will be passed to the callbacks
     *   whenever they are invoked.
     */
    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));
    }
    /**
     * Sets the callback to be used when calling instances created from
     * this template as a function.  If no callback is set, instances
     * behave like normal JavaScript objects that cannot be called as a
     * function.
     */
    void SetCallAsFunctionHandler(FunctionCallback callback,
                                  Handle<Value> data = Handle<Value>());
  
    /**
     * Mark object instances of the template as undetectable.
     *
     * In many ways, undetectable objects behave as though they are not
     * there.  They behave like 'undefined' in conditionals and when
     * printed.  However, properties can be accessed and called as on
     * normal objects.
     */
    void MarkAsUndetectable();
  
    /**
     * Sets access check callbacks on the object template.
     *
     * When accessing properties on instances of this object template,
     * the access check callback will be called to determine whether or
     * not to allow cross-context access to the properties.
     * The last parameter specifies whether access checks are turned
     * on by default on instances. If access checks are off by default,
     * they can be turned on on individual instances by calling
     * Object::TurnOnAccessCheck().
     */
    void SetAccessCheckCallbacks(NamedSecurityCallback named_handler,
                                 IndexedSecurityCallback indexed_handler,
                                 Handle<Value> data = Handle<Value>(),
                                 bool turned_on_by_default = true);
  
    /**
     * Gets the number of internal fields for objects generated from
     * this template.
     */
    int InternalFieldCount();
  
    /**
     * Sets the number of internal fields for objects generated from
     * this template.
     */
    void SetInternalFieldCount(int value);
  
   private:
    ObjectTemplate();
    static Local<ObjectTemplate> New(internal::Isolate* isolate,
                                     Handle<FunctionTemplate> constructor);
    friend class FunctionTemplate;
  };
  
  
  /**
   * A Signature specifies which receivers and arguments are valid
   * parameters to a function.
   */
  class V8_EXPORT Signature : public Data {
   public:
    static Local<Signature> New(Isolate* isolate,
                                Handle<FunctionTemplate> receiver =
                                    Handle<FunctionTemplate>(),
                                int argc = 0,
                                Handle<FunctionTemplate> argv[] = 0);
  
   private:
    Signature();
  };
  
  
  /**
   * An AccessorSignature specifies which receivers are valid parameters
   * to an accessor callback.
   */
  class V8_EXPORT AccessorSignature : public Data {
   public:
    static Local<AccessorSignature> New(Isolate* isolate,
                                        Handle<FunctionTemplate> receiver =
                                            Handle<FunctionTemplate>());
  
   private:
    AccessorSignature();
  };
  
  
  class V8_EXPORT DeclaredAccessorDescriptor : public Data {
   private:
    DeclaredAccessorDescriptor();
  };
  
  
  class V8_EXPORT ObjectOperationDescriptor : public Data {
   public:
    // This function is not yet stable and should not be used at this time.
    static Local<RawOperationDescriptor> NewInternalFieldDereference(
        Isolate* isolate,
        int internal_field);
   private:
    ObjectOperationDescriptor();
  };
  
  
  enum DeclaredAccessorDescriptorDataType {
      kDescriptorBoolType,
      kDescriptorInt8Type, kDescriptorUint8Type,
      kDescriptorInt16Type, kDescriptorUint16Type,
      kDescriptorInt32Type, kDescriptorUint32Type,
      kDescriptorFloatType, kDescriptorDoubleType
  };
  
  
  class V8_EXPORT RawOperationDescriptor : public Data {
   public:
    Local<DeclaredAccessorDescriptor> NewHandleDereference(Isolate* isolate);
    Local<RawOperationDescriptor> NewRawDereference(Isolate* isolate);
    Local<RawOperationDescriptor> NewRawShift(Isolate* isolate,
                                              int16_t byte_offset);
    Local<DeclaredAccessorDescriptor> NewPointerCompare(Isolate* isolate,
                                                        void* compare_value);
    Local<DeclaredAccessorDescriptor> NewPrimitiveValue(
        Isolate* isolate,
        DeclaredAccessorDescriptorDataType data_type,
        uint8_t bool_offset = 0);
    Local<DeclaredAccessorDescriptor> NewBitmaskCompare8(Isolate* isolate,
                                                         uint8_t bitmask,
                                                         uint8_t compare_value);
    Local<DeclaredAccessorDescriptor> NewBitmaskCompare16(
        Isolate* isolate,
        uint16_t bitmask,
        uint16_t compare_value);
    Local<DeclaredAccessorDescriptor> NewBitmaskCompare32(
        Isolate* isolate,
        uint32_t bitmask,
        uint32_t compare_value);
  
   private:
    RawOperationDescriptor();
  };
  
  
  /**
   * A utility for determining the type of objects based on the template
   * they were constructed from.
   */
  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_;
  };
  
  /**
   * Ignore
   */
  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);
  
  
  /**
   * A set of constraints that specifies the limits of the runtime's memory use.
   * You must set the heap size before initializing the VM - the size cannot be
   * adjusted after the VM is initialized.
   *
   * If you are using threads then you should hold the V8::Locker lock while
   * setting the stack limit and you must set a non-default stack limit separately
   * for each thread.
   */
  class V8_EXPORT ResourceConstraints {
   public:
    ResourceConstraints();
  
    /**
     * Configures the constraints with reasonable default values based on the
     * capabilities of the current device the VM is running on.
     *
     * \param physical_memory The total amount of physical memory on the current
     *   device, in bytes.
     * \param virtual_memory_limit The amount of virtual memory on the current
     *   device, in bytes, or zero, if there is no limit.
     * \param number_of_processors The number of CPUs available on the current
     *   device.
     */
    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; }
    int max_available_threads() const { return max_available_threads_; }
    // Set the number of threads available to V8, assuming at least 1.
    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);
  
  /**
   * Create new error objects by calling the corresponding error object
   * constructor with the message.
   */
  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);
  
    /**
     * Creates an error message for the given exception.
     * Will try to reconstruct the original stack trace from the exception value,
     * or capture the current stack trace if not available.
     */
    static Local<Message> CreateMessage(Handle<Value> exception);
  
    /**
     * Returns the original stack trace that was captured at the creation time
     * of a given exception, or an empty handle if not available.
     */
    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,
    kObjectSpaceOldPointerSpace = 1 << 1,
    kObjectSpaceOldDataSpace = 1 << 2,
    kObjectSpaceCodeSpace = 1 << 3,
    kObjectSpaceMapSpace = 1 << 4,
    kObjectSpaceCellSpace = 1 << 5,
    kObjectSpacePropertyCellSpace = 1 << 6,
    kObjectSpaceLoSpace = 1 << 7,
    kObjectSpaceAll = kObjectSpaceNewSpace | kObjectSpaceOldPointerSpace |
                      kObjectSpaceOldDataSpace | 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 ---
  
  /**
   * Callback to check if code generation from strings is allowed. See
   * Context::AllowCodeGenerationFromStrings.
   */
  typedef bool (*AllowCodeGenerationFromStringsCallback)(Local<Context> context);
  
  // --- Garbage Collection Callbacks ---
  
  /**
   * Applications can register callback functions which will be called
   * before and after a garbage collection.  Allocations are not
   * allowed in the callback functions, you therefore cannot manipulate
   * objects (set or delete properties for example) since it is possible
   * such operations will result in the allocation of objects.
   */
  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);
  
  
  /**
   * Collection of V8 heap information.
   *
   * Instances of this class can be passed to v8::V8::HeapStatistics to
   * get heap statistics from V8.
   */
  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 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 used_heap_size_;
    size_t heap_size_limit_;
  
    friend class V8;
    friend class Isolate;
  };
  
  
  class RetainedObjectInfo;
  
  
  /**
   * FunctionEntryHook is the type of the profile entry hook called at entry to
   * any generated function when function-level profiling is enabled.
   *
   * \param function the address of the function that's being entered.
   * \param return_addr_location points to a location on stack where the machine
   *    return address resides. This can be used to identify the caller of
   *    \p function, and/or modified to divert execution when \p function exits.
   *
   * \note the entry hook must not cause garbage collection.
   */
  typedef void (*FunctionEntryHook)(uintptr_t function,
                                    uintptr_t return_addr_location);
  
  /**
   * A JIT code event is issued each time code is added, moved or removed.
   *
   * \note removal events are not currently issued.
   */
  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;
    };
  };
  
  /**
   * Option flags passed to the SetJitCodeEventHandler function.
   */
  enum JitCodeEventOptions {
    kJitCodeEventDefault = 0,
    // Generate callbacks for already existent code.
    kJitCodeEventEnumExisting = 1
  };
  
  
  /**
   * Callback function passed to SetJitCodeEventHandler.
   *
   * \param event code add, move or removal event.
   */
  typedef void (*JitCodeEventHandler)(const JitCodeEvent* event);
  
  
  /**
   * Interface for iterating through all external resources in the heap.
   */
  class V8_EXPORT ExternalResourceVisitor {  // NOLINT
   public:
    virtual ~ExternalResourceVisitor() {}
    virtual void VisitExternalString(Handle<String> string) {}
  };
  
  
  /**
   * Interface for iterating through all the persistent handles in the heap.
   */
  class V8_EXPORT PersistentHandleVisitor {  // NOLINT
   public:
    virtual ~PersistentHandleVisitor() {}
    virtual void VisitPersistentHandle(Persistent<Value>* value,
                                       uint16_t class_id) {}
  };
  
  
  /**
   * Isolate represents an isolated instance of the V8 engine.  V8 isolates have
   * completely separate states.  Objects from one isolate must not be used in
   * other isolates.  The embedder can create multiple isolates and use them in
   * parallel in multiple threads.  An isolate can be entered by at most one
   * thread at any given time.  The Locker/Unlocker API must be used to
   * synchronize.
   */
  class V8_EXPORT Isolate {
   public:
    /**
     * Initial configuration parameters for a new Isolate.
     */
    struct CreateParams {
      CreateParams()
          : entry_hook(NULL),
            code_event_handler(NULL),
            enable_serializer(false) {}
  
      /**
       * The optional entry_hook allows the host application to provide the
       * address of a function that's invoked on entry to every V8-generated
       * function.  Note that entry_hook is invoked at the very start of each
       * generated function. Furthermore, if an  entry_hook is given, V8 will
       * always run without a context snapshot.
       */
      FunctionEntryHook entry_hook;
  
      /**
       * Allows the host application to provide the address of a function that is
       * notified each time code is added, moved or removed.
       */
      JitCodeEventHandler code_event_handler;
  
      /**
       * ResourceConstraints to use for the new Isolate.
       */
      ResourceConstraints constraints;
  
      /**
       * This flag currently renders the Isolate unusable.
       */
      bool enable_serializer;
    };
  
  
    /**
     * Stack-allocated class which sets the isolate for all operations
     * executed within a local scope.
     */
    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&);
    };
  
  
    /**
     * Assert that no Javascript code is invoked.
     */
    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&);
    };
  
  
    /**
     * Introduce exception to 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&);
    };
  
    /**
     * Do not run microtasks while this scope is active, even if microtasks are
     * automatically executed otherwise.
     */
    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&);
    };
  
    /**
     * Types of garbage collections that can be requested via
     * RequestGarbageCollectionForTesting.
     */
    enum GarbageCollectionType {
      kFullGarbageCollection,
      kMinorGarbageCollection
    };
  
    /**
     * Features reported via the SetUseCounterCallback callback. Do not chang
     * assigned numbers of existing items; add new features to the end of this
     * list.
     */
    enum UseCounterFeature {
      kUseAsm = 0,
      kBreakIterator = 1,
      kUseCounterFeatureCount  // This enum value must be last.
    };
  
    typedef void (*UseCounterCallback)(Isolate* isolate,
                                       UseCounterFeature feature);
  
  
    /**
     * Creates a new isolate.  Does not change the currently entered
     * isolate.
     *
     * When an isolate is no longer used its resources should be freed
     * by calling Dispose().  Using the delete operator is not allowed.
     *
     * V8::Initialize() must have run prior to this.
     */
    static Isolate* New(const CreateParams& params = CreateParams());
  
    /**
     * Returns the entered isolate for the current thread or NULL in
     * case there is no current isolate.
     *
     * This method must not be invoked before V8::Initialize() was invoked.
     */
    static Isolate* GetCurrent();
  
    /**
     * Methods below this point require holding a lock (using Locker) in
     * a multi-threaded environment.
     */
  
    /**
     * Sets this isolate as the entered one for the current thread.
     * Saves the previously entered one (if any), so that it can be
     * restored when exiting.  Re-entering an isolate is allowed.
     */
    void Enter();
  
    /**
     * Exits this isolate by restoring the previously entered one in the
     * current thread.  The isolate may still stay the same, if it was
     * entered more than once.
     *
     * Requires: this == Isolate::GetCurrent().
     */
    void Exit();
  
    /**
     * Disposes the isolate.  The isolate must not be entered by any
     * thread to be disposable.
     */
    void Dispose();
  
    /**
     * Associate embedder-specific data with the isolate. |slot| has to be
     * between 0 and GetNumberOfDataSlots() - 1.
     */
    V8_INLINE void SetData(uint32_t slot, void* data);
  
    /**
     * Retrieve embedder-specific data from the isolate.
     * Returns NULL if SetData has never been called for the given |slot|.
     */
    V8_INLINE void* GetData(uint32_t slot);
  
    /**
     * Returns the maximum number of available embedder data slots. Valid slots
     * are in the range of 0 - GetNumberOfDataSlots() - 1.
     */
    V8_INLINE static uint32_t GetNumberOfDataSlots();
  
    /**
     * Get statistics about the heap memory usage.
     */
    void GetHeapStatistics(HeapStatistics* heap_statistics);
  
    /**
     * Get a call stack sample from the isolate.
     * \param state Execution state.
     * \param frames Caller allocated buffer to store stack frames.
     * \param frames_limit Maximum number of frames to capture. The buffer must
     *                     be large enough to hold the number of frames.
     * \param sample_info The sample info is filled up by the function
     *                    provides number of actual captured stack frames and
     *                    the current VM state.
     * \note GetStackSample should only be called when the JS thread is paused or
     *       interrupted. Otherwise the behavior is undefined.
     */
    void GetStackSample(const RegisterState& state, void** frames,
                        size_t frames_limit, SampleInfo* sample_info);
  
    /**
     * Adjusts the amount of registered external memory. Used to give V8 an
     * indication of the amount of externally allocated memory that is kept alive
     * by JavaScript objects. V8 uses this to decide when to perform global
     * garbage collections. Registering externally allocated memory will trigger
     * global garbage collections more often than it would otherwise in an attempt
     * to garbage collect the JavaScript objects that keep the externally
     * allocated memory alive.
     *
     * \param change_in_bytes the change in externally allocated memory that is
     *   kept alive by JavaScript objects.
     * \returns the adjusted value.
     */
    V8_INLINE int64_t
        AdjustAmountOfExternalAllocatedMemory(int64_t change_in_bytes);
  
    /**
     * Returns heap profiler for this isolate. Will return NULL until the isolate
     * is initialized.
     */
    HeapProfiler* GetHeapProfiler();
  
    /**
     * Returns CPU profiler for this isolate. Will return NULL unless the isolate
     * is initialized. It is the embedder's responsibility to stop all CPU
     * profiling activities if it has started any.
     */
    CpuProfiler* GetCpuProfiler();
  
    /** Returns true if this isolate has a current context. */
    bool InContext();
  
    /** Returns the context that is on the top of the stack. */
    Local<Context> GetCurrentContext();
  
    /**
     * Returns the context of the calling JavaScript code.  That is the
     * context of the top-most JavaScript frame.  If there are no
     * JavaScript frames an empty handle is returned.
     */
    Local<Context> GetCallingContext();
  
    /** Returns the last entered context. */
    Local<Context> GetEnteredContext();
  
    /**
     * Schedules an exception to be thrown when returning to JavaScript.  When an
     * exception has been scheduled it is illegal to invoke any JavaScript
     * operation; the caller must return immediately and only after the exception
     * has been handled does it become legal to invoke JavaScript operations.
     */
    Local<Value> ThrowException(Local<Value> exception);
  
    /**
     * Allows the host application to group objects together. If one
     * object in the group is alive, all objects in the group are alive.
     * After each garbage collection, object groups are removed. It is
     * intended to be used in the before-garbage-collection callback
     * function, for instance to simulate DOM tree connections among JS
     * wrapper objects. Object groups for all dependent handles need to
     * be provided for kGCTypeMarkSweepCompact collections, for all other
     * garbage collection types it is sufficient to provide object groups
     * for partially dependent handles only.
     */
    template<typename T> void SetObjectGroupId(const Persistent<T>& object,
                                               UniqueId id);
  
    /**
     * Allows the host application to declare implicit references from an object
     * group to an object. If the objects of the object group are alive, the child
     * object is alive too. After each garbage collection, all implicit references
     * are removed. It is intended to be used in the before-garbage-collection
     * callback function.
     */
    template<typename T> void SetReferenceFromGroup(UniqueId id,
                                                    const Persistent<T>& child);
  
    /**
     * Allows the host application to declare implicit references from an object
     * to another object. If the parent object is alive, the child object is alive
     * too. After each garbage collection, all implicit references are removed. It
     * is intended to be used in the before-garbage-collection callback function.
     */
    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);
  
    /**
     * Enables the host application to receive a notification before a
     * garbage collection. Allocations are allowed in the callback function,
     * but the callback is not re-entrant: if the allocation inside it will
     * trigger the garbage collection, the callback won't be called again.
     * It is possible to specify the GCType filter for your callback. But it is
     * not possible to register the same callback function two times with
     * different GCType filters.
     */
    void AddGCPrologueCallback(
        GCPrologueCallback callback, GCType gc_type_filter = kGCTypeAll);
  
    /**
     * This function removes callback which was installed by
     * AddGCPrologueCallback function.
     */
    void RemoveGCPrologueCallback(GCPrologueCallback callback);
  
    /**
     * Enables the host application to receive a notification after a
     * garbage collection. Allocations are allowed in the callback function,
     * but the callback is not re-entrant: if the allocation inside it will
     * trigger the garbage collection, the callback won't be called again.
     * It is possible to specify the GCType filter for your callback. But it is
     * not possible to register the same callback function two times with
     * different GCType filters.
     */
    void AddGCEpilogueCallback(
        GCEpilogueCallback callback, GCType gc_type_filter = kGCTypeAll);
  
    /**
     * This function removes callback which was installed by
     * AddGCEpilogueCallback function.
     */
    void RemoveGCEpilogueCallback(GCEpilogueCallback callback);
  
  
    /**
     * Forcefully terminate the current thread of JavaScript execution
     * in the given isolate.
     *
     * This method can be used by any thread even if that thread has not
     * acquired the V8 lock with a Locker object.
     */
    void TerminateExecution();
  
    /**
     * Is V8 terminating JavaScript execution.
     *
     * Returns true if JavaScript execution is currently terminating
     * because of a call to TerminateExecution.  In that case there are
     * still JavaScript frames on the stack and the termination
     * exception is still active.
     */
    bool IsExecutionTerminating();
  
    /**
     * Resume execution capability in the given isolate, whose execution
     * was previously forcefully terminated using TerminateExecution().
     *
     * When execution is forcefully terminated using TerminateExecution(),
     * the isolate can not resume execution until all JavaScript frames
     * have propagated the uncatchable exception which is generated.  This
     * method allows the program embedding the engine to handle the
     * termination event and resume execution capability, even if
     * JavaScript frames remain on the stack.
     *
     * This method can be used by any thread even if that thread has not
     * acquired the V8 lock with a Locker object.
     */
    void CancelTerminateExecution();
  
    /**
     * Request V8 to interrupt long running JavaScript code and invoke
     * the given |callback| passing the given |data| to it. After |callback|
     * returns control will be returned to the JavaScript code.
     * There may be a number of interrupt requests in flight.
     * Can be called from another thread without acquiring a |Locker|.
     * Registered |callback| must not reenter interrupted Isolate.
     */
    void RequestInterrupt(InterruptCallback callback, void* data);
  
    /**
     * Clear interrupt request created by |RequestInterrupt|.
     * Can be called from another thread without acquiring a |Locker|.
     */
    V8_DEPRECATED("There's no way to clear interrupts in flight.",
                  void ClearInterrupt());
  
    /**
     * Request garbage collection in this Isolate. It is only valid to call this
     * function if --expose_gc was specified.
     *
     * This should only be used for testing purposes and not to enforce a garbage
     * collection schedule. It has strong negative impact on the garbage
     * collection performance. Use IdleNotification() or LowMemoryNotification()
     * instead to influence the garbage collection schedule.
     */
    void RequestGarbageCollectionForTesting(GarbageCollectionType type);
  
    /**
     * Set the callback to invoke for logging event.
     */
    void SetEventLogger(LogEventCallback that);
  
    /**
     * Adds a callback to notify the host application when a script finished
     * running.  If a script re-enters the runtime during executing, the
     * CallCompletedCallback is only invoked when the outer-most script
     * execution ends.  Executing scripts inside the callback do not trigger
     * further callbacks.
     */
    void AddCallCompletedCallback(CallCompletedCallback callback);
  
    /**
     * Removes callback that was installed by AddCallCompletedCallback.
     */
    void RemoveCallCompletedCallback(CallCompletedCallback callback);
  
  
    /**
     * Set callback to notify about promise reject with no handler, or
     * revocation of such a previous notification once the handler is added.
     */
    void SetPromiseRejectCallback(PromiseRejectCallback callback);
  
    /**
     * Experimental: Runs the Microtask Work Queue until empty
     * Any exceptions thrown by microtask callbacks are swallowed.
     */
    void RunMicrotasks();
  
    /**
     * Experimental: Enqueues the callback to the Microtask Work Queue
     */
    void EnqueueMicrotask(Handle<Function> microtask);
  
    /**
     * Experimental: Enqueues the callback to the Microtask Work Queue
     */
    void EnqueueMicrotask(MicrotaskCallback microtask, void* data = NULL);
  
     /**
     * Experimental: Controls whether the Microtask Work Queue is automatically
     * run when the script call depth decrements to zero.
     */
    void SetAutorunMicrotasks(bool autorun);
  
    /**
     * Experimental: Returns whether the Microtask Work Queue is automatically
     * run when the script call depth decrements to zero.
     */
    bool WillAutorunMicrotasks() const;
  
    /**
     * Sets a callback for counting the number of times a feature of V8 is used.
     */
    void SetUseCounterCallback(UseCounterCallback callback);
  
    /**
     * Enables the host application to provide a mechanism for recording
     * statistics counters.
     */
    void SetCounterFunction(CounterLookupCallback);
  
    /**
     * Enables the host application to provide a mechanism for recording
     * histograms. The CreateHistogram function returns a
     * histogram which will later be passed to the AddHistogramSample
     * function.
     */
    void SetCreateHistogramFunction(CreateHistogramCallback);
    void SetAddHistogramSampleFunction(AddHistogramSampleCallback);
  
    /**
     * Optional notification that the embedder is idle.
     * V8 uses the notification to perform garbage collection.
     * This call can be used repeatedly if the embedder remains idle.
     * Returns true if the embedder should stop calling IdleNotification
     * until real work has been done.  This indicates that V8 has done
     * as much cleanup as it will be able to do.
     *
     * The idle_time_in_ms argument specifies the time V8 has to perform
     * garbage collection. There is no guarantee that the actual work will be
     * done within the time limit.
     * The deadline_in_seconds argument specifies the deadline V8 has to finish
     * garbage collection work. deadline_in_seconds is compared with
     * MonotonicallyIncreasingTime() and should be based on the same timebase as
     * that function. There is no guarantee that the actual work will be done
     * within the time limit.
     */
    bool IdleNotification(int idle_time_in_ms);
    bool IdleNotificationDeadline(double deadline_in_seconds);
  
    /**
     * Optional notification that the system is running low on memory.
     * V8 uses these notifications to attempt to free memory.
     */
    void LowMemoryNotification();
  
    /**
     * Optional notification that a context has been disposed. V8 uses
     * these notifications to guide the GC heuristic. Returns the number
     * of context disposals - including this one - since the last time
     * V8 had a chance to clean up.
     *
     * The optional parameter |dependant_context| specifies whether the disposed
     * context was depending on state from other contexts or not.
     */
    int ContextDisposedNotification(bool dependant_context = true);
  
    /**
     * Allows the host application to provide the address of a function that is
     * notified each time code is added, moved or removed.
     *
     * \param options options for the JIT code event handler.
     * \param event_handler the JIT code event handler, which will be invoked
     *     each time code is added, moved or removed.
     * \note \p event_handler won't get notified of existent code.
     * \note since code removal notifications are not currently issued, the
     *     \p event_handler may get notifications of code that overlaps earlier
     *     code notifications. This happens when code areas are reused, and the
     *     earlier overlapping code areas should therefore be discarded.
     * \note the events passed to \p event_handler and the strings they point to
     *     are not guaranteed to live past each call. The \p event_handler must
     *     copy strings and other parameters it needs to keep around.
     * \note the set of events declared in JitCodeEvent::EventType is expected to
     *     grow over time, and the JitCodeEvent structure is expected to accrue
     *     new members. The \p event_handler function must ignore event codes
     *     it does not recognize to maintain future compatibility.
     * \note Use Isolate::CreateParams to get events for code executed during
     *     Isolate setup.
     */
    void SetJitCodeEventHandler(JitCodeEventOptions options,
                                JitCodeEventHandler event_handler);
  
    /**
     * Modifies the stack limit for this Isolate.
     *
     * \param stack_limit An address beyond which the Vm's stack may not grow.
     *
     * \note  If you are using threads then you should hold the V8::Locker lock
     *     while setting the stack limit and you must set a non-default stack
     *     limit separately for each thread.
     */
    void SetStackLimit(uintptr_t stack_limit);
  
    /**
     * Returns a memory range that can potentially contain jitted code.
     *
     * On Win64, embedders are advised to install function table callbacks for
     * these ranges, as default SEH won't be able to unwind through jitted code.
     *
     * The first page of the code range is reserved for the embedder and is
     * committed, writable, and executable.
     *
     * Might be empty on other platforms.
     *
     * https://code.google.com/p/v8/issues/detail?id=3598
     */
    void GetCodeRange(void** start, size_t* length_in_bytes);
  
    /** Set the callback to invoke in case of fatal errors. */
    void SetFatalErrorHandler(FatalErrorCallback that);
  
    /**
     * Set the callback to invoke to check if code generation from
     * strings should be allowed.
     */
    void SetAllowCodeGenerationFromStringsCallback(
        AllowCodeGenerationFromStringsCallback callback);
  
    /**
    * Check if V8 is dead and therefore unusable.  This is the case after
    * fatal errors such as out-of-memory situations.
    */
    bool IsDead();
  
    /**
     * Adds a message listener.
     *
     * The same message listener can be added more than once and in that
     * case it will be called more than once for each message.
     *
     * If data is specified, it will be passed to the callback when it is called.
     * Otherwise, the exception object will be passed to the callback instead.
     */
    bool AddMessageListener(MessageCallback that,
                            Handle<Value> data = Handle<Value>());
  
    /**
     * Remove all message listeners from the specified callback function.
     */
    void RemoveMessageListeners(MessageCallback that);
  
    /** Callback function for reporting failed access checks.*/
    void SetFailedAccessCheckCallbackFunction(FailedAccessCheckCallback);
  
    /**
     * Tells V8 to capture current stack trace when uncaught exception occurs
     * and report it to the message listeners. The option is off by default.
     */
    void SetCaptureStackTraceForUncaughtExceptions(
        bool capture, int frame_limit = 10,
        StackTrace::StackTraceOptions options = StackTrace::kOverview);
  
    /**
     * Enables the host application to provide a mechanism to be notified
     * and perform custom logging when V8 Allocates Executable Memory.
     */
    void AddMemoryAllocationCallback(MemoryAllocationCallback callback,
                                     ObjectSpace space, AllocationAction action);
  
    /**
     * Removes callback that was installed by AddMemoryAllocationCallback.
     */
    void RemoveMemoryAllocationCallback(MemoryAllocationCallback callback);
  
    /**
     * Iterates through all external resources referenced from current isolate
     * heap.  GC is not invoked prior to iterating, therefore there is no
     * guarantee that visited objects are still alive.
     */
    void VisitExternalResources(ExternalResourceVisitor* visitor);
  
    /**
     * Iterates through all the persistent handles in the current isolate's heap
     * that have class_ids.
     */
    void VisitHandlesWithClassIds(PersistentHandleVisitor* visitor);
  
    /**
     * Iterates through all the persistent handles in the current isolate's heap
     * that have class_ids and are candidates to be marked as partially dependent
     * handles. This will visit handles to young objects created since the last
     * garbage collection but is free to visit an arbitrary superset of these
     * objects.
     */
    void VisitHandlesForPartialDependence(PersistentHandleVisitor* visitor);
  
   private:
    template<class K, class V, class Traits> friend class PersistentValueMap;
  
    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;
  };
  
  
  /**
   * EntropySource is used as a callback function when v8 needs a source
   * of entropy.
   */
  typedef bool (*EntropySource)(unsigned char* buffer, size_t length);
  
  
  /**
   * ReturnAddressLocationResolver is used as a callback function when v8 is
   * resolving the location of a return address on the stack. Profilers that
   * change the return address on the stack can use this to resolve the stack
   * location to whereever the profiler stashed the original return address.
   *
   * \param return_addr_location points to a location on stack where a machine
   *    return address resides.
   * \returns either return_addr_location, or else a pointer to the profiler's
   *    copy of the original return address.
   *
   * \note the resolver function must not cause garbage collection.
   */
  typedef uintptr_t (*ReturnAddressLocationResolver)(
      uintptr_t return_addr_location);
  
  
  /**
   * Container class for static utility functions.
   */
  class V8_EXPORT V8 {
   public:
    /** Set the callback to invoke in case of fatal errors. */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void SetFatalErrorHandler(FatalErrorCallback that);
  
    /**
     * Set the callback to invoke to check if code generation from
     * strings should be allowed.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void SetAllowCodeGenerationFromStringsCallback(
        AllowCodeGenerationFromStringsCallback that);
  
    /**
     * Set allocator to use for ArrayBuffer memory.
     * The allocator should be set only once. The allocator should be set
     * before any code tha uses ArrayBuffers is executed.
     * This allocator is used in all isolates.
     */
    static void SetArrayBufferAllocator(ArrayBuffer::Allocator* allocator);
  
    /**
    * Check if V8 is dead and therefore unusable.  This is the case after
    * fatal errors such as out-of-memory situations.
    */
    // TODO(dcarney): deprecate this.
    V8_INLINE static bool IsDead();
  
    /**
     * Hand startup data to V8, in case the embedder has chosen to build
     * V8 with external startup data.
     *
     * Note:
     * - By default the startup data is linked into the V8 library, in which
     *   case this function is not meaningful.
     * - If this needs to be called, it needs to be called before V8
     *   tries to make use of its built-ins.
     * - To avoid unnecessary copies of data, V8 will point directly into the
     *   given data blob, so pretty please keep it around until V8 exit.
     * - Compression of the startup blob might be useful, but needs to
     *   handled entirely on the embedders' side.
     * - The call will abort if the data is invalid.
     */
    static void SetNativesDataBlob(StartupData* startup_blob);
    static void SetSnapshotDataBlob(StartupData* startup_blob);
  
    /**
     * Create a new isolate and context for the purpose of capturing a snapshot
     * Returns { NULL, 0 } on failure.
     * The caller owns the data array in the return value.
     */
    static StartupData CreateSnapshotDataBlob();
  
    /**
     * Adds a message listener.
     *
     * The same message listener can be added more than once and in that
     * case it will be called more than once for each message.
     *
     * If data is specified, it will be passed to the callback when it is called.
     * Otherwise, the exception object will be passed to the callback instead.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static bool AddMessageListener(
        MessageCallback that, Handle<Value> data = Handle<Value>());
  
    /**
     * Remove all message listeners from the specified callback function.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void RemoveMessageListeners(MessageCallback that);
  
    /**
     * Tells V8 to capture current stack trace when uncaught exception occurs
     * and report it to the message listeners. The option is off by default.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void SetCaptureStackTraceForUncaughtExceptions(
        bool capture, int frame_limit = 10,
        StackTrace::StackTraceOptions options = StackTrace::kOverview);
  
    /**
     * Sets V8 flags from a string.
     */
    static void SetFlagsFromString(const char* str, int length);
  
    /**
     * Sets V8 flags from the command line.
     */
    static void SetFlagsFromCommandLine(int* argc,
                                        char** argv,
                                        bool remove_flags);
  
    /** Get the version string. */
    static const char* GetVersion();
  
    /** Callback function for reporting failed access checks.*/
    // TODO(dcarney): deprecate this.
    V8_INLINE static void SetFailedAccessCheckCallbackFunction(
        FailedAccessCheckCallback);
  
    /**
     * Enables the host application to receive a notification before a
     * garbage collection.  Allocations are not allowed in the
     * callback function, you therefore cannot manipulate objects (set
     * or delete properties for example) since it is possible such
     * operations will result in the allocation of objects. It is possible
     * to specify the GCType filter for your callback. But it is not possible to
     * register the same callback function two times with different
     * GCType filters.
     */
    // TODO(dcarney): deprecate this.
    static void AddGCPrologueCallback(
        GCPrologueCallback callback, GCType gc_type_filter = kGCTypeAll);
  
    /**
     * This function removes callback which was installed by
     * AddGCPrologueCallback function.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void RemoveGCPrologueCallback(GCPrologueCallback callback);
  
    /**
     * Enables the host application to receive a notification after a
     * garbage collection.  Allocations are not allowed in the
     * callback function, you therefore cannot manipulate objects (set
     * or delete properties for example) since it is possible such
     * operations will result in the allocation of objects. It is possible
     * to specify the GCType filter for your callback. But it is not possible to
     * register the same callback function two times with different
     * GCType filters.
     */
    // TODO(dcarney): deprecate this.
    static void AddGCEpilogueCallback(
        GCEpilogueCallback callback, GCType gc_type_filter = kGCTypeAll);
  
    /**
     * This function removes callback which was installed by
     * AddGCEpilogueCallback function.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void RemoveGCEpilogueCallback(GCEpilogueCallback callback);
  
    /**
     * Enables the host application to provide a mechanism to be notified
     * and perform custom logging when V8 Allocates Executable Memory.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void AddMemoryAllocationCallback(
        MemoryAllocationCallback callback, ObjectSpace space,
        AllocationAction action);
  
    /**
     * Removes callback that was installed by AddMemoryAllocationCallback.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void RemoveMemoryAllocationCallback(
        MemoryAllocationCallback callback);
  
    /**
     * Initializes V8. This function needs to be called before the first Isolate
     * is created. It always returns true.
     */
    static bool Initialize();
  
    /**
     * Allows the host application to provide a callback which can be used
     * as a source of entropy for random number generators.
     */
    static void SetEntropySource(EntropySource source);
  
    /**
     * Allows the host application to provide a callback that allows v8 to
     * cooperate with a profiler that rewrites return addresses on stack.
     */
    static void SetReturnAddressLocationResolver(
        ReturnAddressLocationResolver return_address_resolver);
  
    /**
     * Forcefully terminate the current thread of JavaScript execution
     * in the given isolate.
     *
     * This method can be used by any thread even if that thread has not
     * acquired the V8 lock with a Locker object.
     *
     * \param isolate The isolate in which to terminate the current JS execution.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void TerminateExecution(Isolate* isolate);
  
    /**
     * Is V8 terminating JavaScript execution.
     *
     * Returns true if JavaScript execution is currently terminating
     * because of a call to TerminateExecution.  In that case there are
     * still JavaScript frames on the stack and the termination
     * exception is still active.
     *
     * \param isolate The isolate in which to check.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static bool IsExecutionTerminating(Isolate* isolate = NULL);
  
    /**
     * Resume execution capability in the given isolate, whose execution
     * was previously forcefully terminated using TerminateExecution().
     *
     * When execution is forcefully terminated using TerminateExecution(),
     * the isolate can not resume execution until all JavaScript frames
     * have propagated the uncatchable exception which is generated.  This
     * method allows the program embedding the engine to handle the
     * termination event and resume execution capability, even if
     * JavaScript frames remain on the stack.
     *
     * This method can be used by any thread even if that thread has not
     * acquired the V8 lock with a Locker object.
     *
     * \param isolate The isolate in which to resume execution capability.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void CancelTerminateExecution(Isolate* isolate);
  
    /**
     * Releases any resources used by v8 and stops any utility threads
     * that may be running.  Note that disposing v8 is permanent, it
     * cannot be reinitialized.
     *
     * It should generally not be necessary to dispose v8 before exiting
     * a process, this should happen automatically.  It is only necessary
     * to use if the process needs the resources taken up by v8.
     */
    static bool Dispose();
  
    /**
     * Iterates through all external resources referenced from current isolate
     * heap.  GC is not invoked prior to iterating, therefore there is no
     * guarantee that visited objects are still alive.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void VisitExternalResources(
        ExternalResourceVisitor* visitor);
  
    /**
     * Iterates through all the persistent handles in the current isolate's heap
     * that have class_ids.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void VisitHandlesWithClassIds(
        PersistentHandleVisitor* visitor);
  
    /**
     * Iterates through all the persistent handles in isolate's heap that have
     * class_ids.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void VisitHandlesWithClassIds(
        Isolate* isolate, PersistentHandleVisitor* visitor);
  
    /**
     * Iterates through all the persistent handles in the current isolate's heap
     * that have class_ids and are candidates to be marked as partially dependent
     * handles. This will visit handles to young objects created since the last
     * garbage collection but is free to visit an arbitrary superset of these
     * objects.
     */
    // TODO(dcarney): deprecate this.
    V8_INLINE static void VisitHandlesForPartialDependence(
        Isolate* isolate, PersistentHandleVisitor* visitor);
  
    /**
     * Initialize the ICU library bundled with V8. The embedder should only
     * invoke this method when using the bundled ICU. Returns true on success.
     *
     * If V8 was compiled with the ICU data in an external file, the location
     * of the data file has to be provided.
     */
    static bool InitializeICU(const char* icu_data_file = NULL);
  
    /**
     * Sets the v8::Platform to use. This should be invoked before V8 is
     * initialized.
     */
    static void InitializePlatform(Platform* platform);
  
    /**
     * Clears all references to the v8::Platform. This should be invoked after
     * V8 was disposed.
     */
    static void ShutdownPlatform();
  
   private:
    V8();
  
    enum WeakHandleType { PhantomHandle, NonphantomHandle };
  
    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 MakePhantom(internal::Object** global_handle, void* data,
                            PhantomCallbackData<void>::Callback weak_callback);
    static void MakePhantom(
        internal::Object** global_handle,
        InternalFieldsCallbackData<void, void>::Callback weak_callback,
        int internal_field_index1,
        int internal_field_index2 = Object::kNoInternalFieldIndex);
    static void* ClearWeak(internal::Object** global_handle);
    static void Eternalize(Isolate* isolate,
                           Value* handle,
                           int* index);
    static Local<Value> GetEternal(Isolate* isolate, int index);
  
    template <class T> friend class Handle;
    template <class T> friend class Local;
    template <class T> friend class Eternal;
    template <class T> friend class PersistentBase;
    template <class T, class M> friend class Persistent;
    friend class Context;
  };
  
  
  /**
   * An external exception handler.
   */
  class V8_EXPORT TryCatch {
   public:
    /**
     * Creates a new try/catch block and registers it with v8.  Note that
     * all TryCatch blocks should be stack allocated because the memory
     * location itself is compared against JavaScript try/catch blocks.
     */
    // TODO(dcarney): deprecate.
    TryCatch();
  
    /**
     * Creates a new try/catch block and registers it with v8.  Note that
     * all TryCatch blocks should be stack allocated because the memory
     * location itself is compared against JavaScript try/catch blocks.
     */
    TryCatch(Isolate* isolate);
  
    /**
     * Unregisters and deletes this try/catch block.
     */
    ~TryCatch();
  
    /**
     * Returns true if an exception has been caught by this try/catch block.
     */
    bool HasCaught() const;
  
    /**
     * For certain types of exceptions, it makes no sense to continue execution.
     *
     * If CanContinue returns false, the correct action is to perform any C++
     * cleanup needed and then return.  If CanContinue returns false and
     * HasTerminated returns true, it is possible to call
     * CancelTerminateExecution in order to continue calling into the engine.
     */
    bool CanContinue() const;
  
    /**
     * Returns true if an exception has been caught due to script execution
     * being terminated.
     *
     * There is no JavaScript representation of an execution termination
     * exception.  Such exceptions are thrown when the TerminateExecution
     * methods are called to terminate a long-running script.
     *
     * If such an exception has been thrown, HasTerminated will return true,
     * indicating that it is possible to call CancelTerminateExecution in order
     * to continue calling into the engine.
     */
    bool HasTerminated() const;
  
    /**
     * Throws the exception caught by this TryCatch in a way that avoids
     * it being caught again by this same TryCatch.  As with ThrowException
     * it is illegal to execute any JavaScript operations after calling
     * ReThrow; the caller must return immediately to where the exception
     * is caught.
     */
    Handle<Value> ReThrow();
  
    /**
     * Returns the exception caught by this try/catch block.  If no exception has
     * been caught an empty handle is returned.
     *
     * The returned handle is valid until this TryCatch block has been destroyed.
     */
    Local<Value> Exception() const;
  
    /**
     * Returns the .stack property of the thrown object.  If no .stack
     * property is present an empty handle is returned.
     */
    Local<Value> StackTrace() const;
  
    /**
     * Returns the message associated with this exception.  If there is
     * no message associated an empty handle is returned.
     *
     * The returned handle is valid until this TryCatch block has been
     * destroyed.
     */
    Local<v8::Message> Message() const;
  
    /**
     * Clears any exceptions that may have been caught by this try/catch block.
     * After this method has been called, HasCaught() will return false. Cancels
     * the scheduled exception if it is caught and ReThrow() is not called before.
     *
     * It is not necessary to clear a try/catch block before using it again; if
     * another exception is thrown the previously caught exception will just be
     * overwritten.  However, it is often a good idea since it makes it easier
     * to determine which operation threw a given exception.
     */
    void Reset();
  
    /**
     * Set verbosity of the external exception handler.
     *
     * By default, exceptions that are caught by an external exception
     * handler are not reported.  Call SetVerbose with true on an
     * external exception handler to have exceptions caught by the
     * handler reported as if they were not caught.
     */
    void SetVerbose(bool value);
  
    /**
     * Set whether or not this TryCatch should capture a Message object
     * which holds source information about where the exception
     * occurred.  True by default.
     */
    void SetCaptureMessage(bool value);
  
    /**
     * There are cases when the raw address of C++ TryCatch object cannot be
     * used for comparisons with addresses into the JS stack. The cases are:
     * 1) ARM, ARM64 and MIPS simulators which have separate JS stack.
     * 2) Address sanitizer allocates local C++ object in the heap when
     *    UseAfterReturn mode is enabled.
     * This method returns address that can be used for comparisons with
     * addresses into the JS stack. When neither simulator nor ASAN's
     * UseAfterReturn is enabled, then the address returned will be the address
     * of the C++ try catch handler itself.
     */
    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* message_script_;
    void* js_stack_comparable_address_;
    int message_start_pos_;
    int message_end_pos_;
    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 ---
  
  
  /**
   * A container for extension names.
   */
  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_;
  };
  
  
  /**
   * A sandboxed execution context with its own set of built-in objects
   * and functions.
   */
  class V8_EXPORT Context {
   public:
    /**
     * Returns the global proxy object.
     *
     * Global proxy object is a thin wrapper whose prototype points to actual
     * context's global object with the properties like Object, etc. This is done
     * that way for security reasons (for more details see
     * https://wiki.mozilla.org/Gecko:SplitWindow).
     *
     * Please note that changes to global proxy object prototype most probably
     * would break VM---v8 expects only global object as a prototype of global
     * proxy object.
     */
    Local<Object> Global();
  
    /**
     * Detaches the global object from its context before
     * the global object can be reused to create a new context.
     */
    void DetachGlobal();
  
    /**
     * Creates a new context and returns a handle to the newly allocated
     * context.
     *
     * \param isolate The isolate in which to create the context.
     *
     * \param extensions An optional extension configuration containing
     * the extensions to be installed in the newly created context.
     *
     * \param global_template An optional object template from which the
     * global object for the newly created context will be created.
     *
     * \param global_object An optional global object to be reused for
     * the newly created context. This global object must have been
     * created by a previous call to Context::New with the same global
     * template. The state of the global object will be completely reset
     * and only object identify will remain.
     */
    static Local<Context> New(
        Isolate* isolate,
        ExtensionConfiguration* extensions = NULL,
        Handle<ObjectTemplate> global_template = Handle<ObjectTemplate>(),
        Handle<Value> global_object = Handle<Value>());
  
    /**
     * Sets the security token for the context.  To access an object in
     * another context, the security tokens must match.
     */
    void SetSecurityToken(Handle<Value> token);
  
    /** Restores the security token to the default value. */
    void UseDefaultSecurityToken();
  
    /** Returns the security token of this context.*/
    Handle<Value> GetSecurityToken();
  
    /**
     * Enter this context.  After entering a context, all code compiled
     * and run is compiled and run in this context.  If another context
     * is already entered, this old context is saved so it can be
     * restored when the new context is exited.
     */
    void Enter();
  
    /**
     * Exit this context.  Exiting the current context restores the
     * context that was in place when entering the current context.
     */
    void Exit();
  
    /** Returns an isolate associated with a current context. */
    v8::Isolate* GetIsolate();
  
    /**
     * Gets the embedder data with the given index, which must have been set by a
     * previous call to SetEmbedderData with the same index. Note that index 0
     * currently has a special meaning for Chrome's debugger.
     */
    V8_INLINE Local<Value> GetEmbedderData(int index);
  
    /**
     * Sets the embedder data with the given index, growing the data as
     * needed. Note that index 0 currently has a special meaning for Chrome's
     * debugger.
     */
    void SetEmbedderData(int index, Handle<Value> value);
  
    /**
     * Gets a 2-byte-aligned native pointer from the embedder data with the given
     * index, which must have bees set by a previous call to
     * SetAlignedPointerInEmbedderData with the same index. Note that index 0
     * currently has a special meaning for Chrome's debugger.
     */
    V8_INLINE void* GetAlignedPointerFromEmbedderData(int index);
  
    /**
     * Sets a 2-byte-aligned native pointer in the embedder data with the given
     * index, growing the data as needed. Note that index 0 currently has a
     * special meaning for Chrome's debugger.
     */
    void SetAlignedPointerInEmbedderData(int index, void* value);
  
    /**
     * Control whether code generation from strings is allowed. Calling
     * this method with false will disable 'eval' and the 'Function'
     * constructor for code running in this context. If 'eval' or the
     * 'Function' constructor are used an exception will be thrown.
     *
     * If code generation from strings is not allowed the
     * V8::AllowCodeGenerationFromStrings callback will be invoked if
     * set before blocking the call to 'eval' or the 'Function'
     * constructor. If that callback returns true, the call will be
     * allowed, otherwise an exception will be thrown. If no callback is
     * set an exception will be thrown.
     */
    void AllowCodeGenerationFromStrings(bool allow);
  
    /**
     * Returns true if code generation from strings is allowed for the context.
     * For more details see AllowCodeGenerationFromStrings(bool) documentation.
     */
    bool IsCodeGenerationFromStringsAllowed();
  
    /**
     * Sets the error description for the exception that is thrown when
     * code generation from strings is not allowed and 'eval' or the 'Function'
     * constructor are called.
     */
    void SetErrorMessageForCodeGenerationFromStrings(Handle<String> message);
  
    /**
     * Stack-allocated class which sets the execution context for all
     * operations executed within a local scope.
     */
    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);
  };
  
  
  /**
   * Multiple threads in V8 are allowed, but only one thread at a time is allowed
   * to use any given V8 isolate, see the comments in the Isolate class. The
   * definition of 'using a V8 isolate' includes accessing handles or holding onto
   * object pointers obtained from V8 handles while in the particular V8 isolate.
   * It is up to the user of V8 to ensure, perhaps with locking, that this
   * constraint is not violated. In addition to any other synchronization
   * mechanism that may be used, the v8::Locker and v8::Unlocker classes must be
   * used to signal thead switches to V8.
   *
   * v8::Locker is a scoped lock object. While it's active, i.e. between its
   * construction and destruction, the current thread is allowed to use the locked
   * isolate. V8 guarantees that an isolate can be locked by at most one thread at
   * any time. In other words, the scope of a v8::Locker is a critical section.
   *
   * Sample usage:
  * \code
   * ...
   * {
   *   v8::Locker locker(isolate);
   *   v8::Isolate::Scope isolate_scope(isolate);
   *   ...
   *   // Code using V8 and isolate goes here.
   *   ...
   * } // Destructor called here
   * \endcode
   *
   * If you wish to stop using V8 in a thread A you can do this either by
   * destroying the v8::Locker object as above or by constructing a v8::Unlocker
   * object:
   *
   * \code
   * {
   *   isolate->Exit();
   *   v8::Unlocker unlocker(isolate);
   *   ...
   *   // Code not using V8 goes here while V8 can run in another thread.
   *   ...
   * } // Destructor called here.
   * isolate->Enter();
   * \endcode
   *
   * The Unlocker object is intended for use in a long-running callback from V8,
   * where you want to release the V8 lock for other threads to use.
   *
   * The v8::Locker is a recursive lock, i.e. you can lock more than once in a
   * given thread. This can be useful if you have code that can be called either
   * from code that holds the lock or from code that does not. The Unlocker is
   * not recursive so you can not have several Unlockers on the stack at once, and
   * you can not use an Unlocker in a thread that is not inside a Locker's scope.
   *
   * An unlocker will unlock several lockers if it has to and reinstate the
   * correct depth of locking on its destruction, e.g.:
   *
   * \code
   * // V8 not locked.
   * {
   *   v8::Locker locker(isolate);
   *   Isolate::Scope isolate_scope(isolate);
   *   // V8 locked.
   *   {
   *     v8::Locker another_locker(isolate);
   *     // V8 still locked (2 levels).
   *     {
   *       isolate->Exit();
   *       v8::Unlocker unlocker(isolate);
   *       // V8 not locked.
   *     }
   *     isolate->Enter();
   *     // V8 locked again (2 levels).
   *   }
   *   // V8 still locked (1 level).
   * }
   * // V8 Now no longer locked.
   * \endcode
   */
  class V8_EXPORT Unlocker {
   public:
    /**
     * Initialize Unlocker for a given Isolate.
     */
    V8_INLINE explicit Unlocker(Isolate* isolate) { Initialize(isolate); }
  
    ~Unlocker();
   private:
    void Initialize(Isolate* isolate);
  
    internal::Isolate* isolate_;
  };
  
  
  class V8_EXPORT Locker {
   public:
    /**
     * Initialize Locker for a given Isolate.
     */
    V8_INLINE explicit Locker(Isolate* isolate) { Initialize(isolate); }
  
    ~Locker();
  
    /**
     * Returns whether or not the locker for a given isolate, is locked by the
     * current thread.
     */
    static bool IsLocked(Isolate* isolate);
  
    /**
     * Returns whether v8::Locker is being used by this V8 instance.
     */
    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; }
  
  /**
   * This class exports constants and functionality from within v8 that
   * is necessary to implement inline functions in the v8 api.  Don't
   * depend on functions and constants defined here.
   */
  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 = 76;
    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 = 154;
  
    // 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 = 0xbd;
    static const int kFirstNonstringType = 0x80;
    static const int kOddballType = 0x83;
    static const int kForeignType = 0x88;
  
    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() : Handle<T>() { }
  
  
  template <class T>
  Local<T> Local<T>::New(Isolate* isolate, Handle<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>
  Handle<T> Handle<T>::New(Isolate* isolate, T* that) {
    if (that == NULL) return Handle<T>();
    T* that_ptr = that;
    internal::Object** p = reinterpret_cast<internal::Object**>(that_ptr);
    return Handle<T>(reinterpret_cast<T*>(HandleScope::CreateHandle(
        reinterpret_cast<internal::Isolate*>(isolate), *p)));
  }
  
  
  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>
  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 PhantomCallbackData<P>::Callback callback) {
    typedef typename PhantomCallbackData<void>::Callback Callback;
    V8::MakePhantom(reinterpret_cast<internal::Object**>(this->val_), parameter,
                    reinterpret_cast<Callback>(callback));
  }
  
  
  template <class T>
  template <typename U, typename V>
  void PersistentBase<T>::SetPhantom(
      void (*callback)(const InternalFieldsCallbackData<U, V>&),
      int internal_field_index1, int internal_field_index2) {
    typedef typename InternalFieldsCallbackData<void, void>::Callback Callback;
    V8::MakePhantom(reinterpret_cast<internal::Object**>(this->val_),
                    reinterpret_cast<Callback>(callback), internal_field_index1,
                    internal_field_index2);
  }
  
  
  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_;
  }
  
  
  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::ResourceIsSharedCrossOrigin() const {
    return resource_is_shared_cross_origin_;
  }
  
  
  Handle<Integer> ScriptOrigin::ScriptID() const {
    return script_id_;
  }
  
  
  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_shared_cross_origin(origin.ResourceIsSharedCrossOrigin()),
        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()); }
  
  
  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);
  }
  
  
  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.");
    } else {
      *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);
  }
  
  /**
   * \example shell.cc
   * A simple shell that takes a list of expressions on the
   * command-line and executes them.
   */
  
  
  /**
   * \example process.cc
   */
  
  
  }  // namespace v8
  
  
  #undef TYPE_CHECK
  
  
  #endif  // V8_H_
  