public/v8.h

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// modification, are permitted provided that the following conditions are
// met:
//
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/** \mainpage V8 API Reference Guide

  Add text to introduce,

  point back to code.google.com/apis/v8/index.html

  etc etc etc
 */
#ifndef _V8
#define _V8

#include <stdio.h>

#ifdef _WIN32
typedef int int32_t;
typedef unsigned int uint32_t;
typedef unsigned short uint16_t;
typedef long long int64_t;
#else
#include <stdint.h>
#endif

/**
 * The v8 javascript engine.
 */
namespace v8 {

class Context;
class String;
class Value;
class Utils;
class Number;
class Object;
class Array;
class Int32;
class Uint32;
class External;
class Primitive;
class Boolean;
class Integer;
class Function;
class Date;
class ImplementationUtilities;
class Signature;
template <class T> class Handle;
template <class T> class Local;
template <class T> class Persistent;
class FunctionTemplate;
class ObjectTemplate;
class Data;


// --- W e a k  H a n d l e s


/**
 * A weak reference callback function.
 *
 * \param object the weak global object to be reclaimed by the garbage collector
 * \param parameter the value passed in when making the weak global object
 */
typedef void (*WeakReferenceCallback)(Persistent<Object> object,
                                      void* parameter);


// --- H a n d l e s ---

#define TYPE_CHECK(T, S)                              \
  while (false) {                                     \
    *(static_cast<T**>(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
 * an 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.
   */
  Handle();

  /**
   * Creates a new handle for the specified value.
   */
  explicit Handle(T* val) : val_(val) { }

  /**
   * Creates a handle for the contents of the specified handle.  This
   * constructor allows you to pass handles as arguments by value and
   * 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 compiletime 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> 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.
   */
  bool IsEmpty() { return val_ == 0; }

  T* operator->();

  T* operator*();

  /**
   * Sets the handle to be empty. IsEmpty() will then return true.
   */
  void Clear() { this->val_ = 0; }

  /**
   * 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> bool operator==(Handle<S> that) {
    void** a = reinterpret_cast<void**>(**this);
    void** b = reinterpret_cast<void**>(*that);
    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> bool operator!=(Handle<S> that) {
    return !operator==(that);
  }

  template <class S> static inline Handle<T> Cast(Handle<S> that) {
    if (that.IsEmpty()) return Handle<T>();
    return Handle<T>(T::Cast(*that));
  }

 private:
  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:
  Local();
  template <class S> 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> inline Local(S* that) : Handle<T>(that) { }
  template <class S> static inline Local<T> Cast(Local<S> that) {
    if (that.IsEmpty()) return Local<T>();
    return Local<T>(T::Cast(*that));
  }

  /** 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.
   */
  static Local<T> New(Handle<T> that);
};


/**
 * An object reference that is independent of any handle scope.  Where
 * a Local handle only lives as long as the HandleScope where it was
 * allocated, a Persistent 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 Persistent::New and existing handles can
 * be disposed using Persistent::Dispose.  Since persistent handles
 * are passed by value you may have many persistent handle objects
 * that point to the same storage cell.  For instance, if you pass a
 * persistent handle as an argument to a function you will not get two
 * different storage cells but rather two references to the same
 * storage cell.
 */
template <class T> class Persistent : public Handle<T> {
 public:

  /**
   * Creates an empty persistent handle that doesn't point to any
   * storage cell.
   */
  Persistent();

  /**
   * Creates a persistent handle for the same storage cell as the
   * specified handle.  This constructor allows you to pass persistent
   * handles as arguments by value and to assign between persistent
   * handles.  However, if you try to assign between incompatible
   * persistent handles, for instance from a Persistent<String> to a
   * Persistent<Number> it will cause a compiletime error.  Assigning
   * between compatible persistent handles, for instance assigning a
   * Persistent<String> to a variable declared as Persistent<Value>,
   * is legal because String is a subclass of Value.
   */
  template <class S> inline Persistent(Persistent<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> inline Persistent(S* that) : Handle<T>(that) { }

  template <class S> explicit inline Persistent(Handle<S> that)
      : Handle<T>(*that) { }

  template <class S> static inline Persistent<T> Cast(Persistent<S> that) {
    if (that.IsEmpty()) return Persistent<T>();
    return Persistent<T>(T::Cast(*that));
  }

  /**
   * Creates a new persistent handle for an existing (local or
   * persistent) handle.
   */
  static Persistent<T> New(Handle<T> that);

  /**
   * Releases the storage cell referenced by this persistent handle.
   * Does not remove the reference to the cell from any handles.
   * This handle's reference, and any any other references to the storage
   * cell remain and IsEmpty will still return false.
   */
  void Dispose();

  /**
   * Make the reference to this object weak.  When only weak handles
   * refer to the object, the garbage collector will perform a
   * callback to the given V8::WeakReferenceCallback function, passing
   * it the object reference and the given parameters.
   */
  void MakeWeak(void* parameters, WeakReferenceCallback callback);

  /** Clears the weak reference to this object.*/
  void ClearWeak();

  /**
   *Checks if the handle holds the only reference to an object.
   */
  bool IsNearDeath();

  /**
   * Returns true if the handle's reference is weak.
   */
  bool IsWeak();

 private:
  friend class ImplementationUtilities;
  friend class ObjectTemplate;
};


/**
 * 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 that 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 HandleScope {
 public:
  HandleScope() : previous_(current_), is_closed_(false) {
    current_.extensions = 0;
  }

  ~HandleScope() {
    // TODO(1245391): In a perfect world, there would be a way of not
    // having to check for expl icitly closed scopes maybe through
    // subclassing HandleScope?
    if (!is_closed_) RestorePreviousState();
  }

  /**
   * TODO(1245391): Consider introducing a subclass for this.
   * Closes the handle scope and returns the value as a handle in the
   * previous scope, which is the new current scope after the call.
   */
  template <class T> Local<T> Close(Handle<T> value);

  /**
   * Counts the number of allocated handles.
   */
  static int NumberOfHandles();

  /**
   * Creates a new handle with the given value.
   */
  static void** CreateHandle(void* value);

 private:
  // Make it impossible 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);

  class Data {
   public:
    int extensions;
    void** next;
    void** limit;
    inline void Initialize() {
      extensions = -1;
      next = limit = NULL;
    }
  };

  static Data current_;
  const Data previous_;

  /**
   * Re-establishes the previous scope state. Should not be called for
   * any other scope than the current scope and not more than once.
   */
  void RestorePreviousState() {
    if (current_.extensions > 0) DeleteExtensions();
    current_ = previous_;
#ifdef DEBUG
    ZapRange(current_.next, current_.limit);
#endif
  }

  // TODO(1245391): Consider creating a subclass for this.
  bool is_closed_;
  void** RawClose(void** value);

  /** Deallocates any extensions used by the current scope.*/
  static void DeleteExtensions();

#ifdef DEBUG
  // Zaps the handles in the half-open interval [start, end).
  static void ZapRange(void** start, void** end);
#endif

  friend class ImplementationUtilities;
};


// --- S p e c i a l   o b j e c t s ---


/**
 * The superclass of values and API object templates.
 */
class Data {
 private:
  Data();
};


/**
 * Pre-compilation data that can be associated with a script.  This
 * data can be calculated for a script in advance of actually
 * compiling it, and stored between compilations.  When script data
 * is given to the compile method compilation will be faster.
 */
class ScriptData {
 public:
  virtual ~ScriptData() { }
  static ScriptData* PreCompile(const char* input, int length);
  static ScriptData* New(unsigned* data, int length);

  virtual int Length() = 0;
  virtual unsigned* Data() = 0;
};


/**
 * The origin, within a file, of a script.
 */
class ScriptOrigin {
 public:
  ScriptOrigin(Handle<String> resource_name,
               Handle<Integer> resource_line_offset = Handle<Integer>(),
               Handle<Integer> resource_column_offset = Handle<Integer>())
      : resource_name_(resource_name),
        resource_line_offset_(resource_line_offset),
        resource_column_offset_(resource_column_offset) { }
  inline Handle<String> ResourceName();
  inline Handle<Integer> ResourceLineOffset();
  inline Handle<Integer> ResourceColumnOffset();
 private:
  Handle<String> resource_name_;
  Handle<Integer> resource_line_offset_;
  Handle<Integer> resource_column_offset_;
};


/**
 * A compiled javascript script.
 */
class Script {
 public:

  /**
   * Compiles the specified script. The ScriptOrigin* and ScriptData*
   * parameters are owned by the caller of Script::Compile. No
   * references to these objects are kept after compilation finishes.
   */
  static Local<Script> Compile(Handle<String> source,
                               ScriptOrigin* origin = NULL,
                               ScriptData* pre_data = NULL);

  Local<Value> Run();
};


/**
 * An error message.
 */
class Message {
 public:
  Local<String> Get();
  Local<Value> GetSourceLine();

  // TODO(1241256): Rewrite (or remove) this method.  We don't want to
  // deal with ownership of the returned string and we want to use
  // javascript data structures exclusively.
  char* GetUnderline(char* source_line, char underline_char);

  Handle<String> GetScriptResourceName();

  // TODO(1240903): Remove this when no longer used in WebKit V8
  // bindings.
  Handle<Value> GetSourceData();

  int GetLineNumber();

  // TODO(1245381): Print to a string instead of on a FILE.
  static void PrintCurrentStackTrace(FILE* out);
};


// --- V a l u e ---


/**
 * The superclass of all javascript values and objects.
 */
class Value : public Data {
 public:

  /**
   * Returns true if this value is the undefined value.  See ECMA-262
   * 4.3.10.
   */
  bool IsUndefined();

  /**
   * Returns true if this value is the null value.  See ECMA-262
   * 4.3.11.
   */
  bool IsNull();

   /**
   * Returns true if this value is true.
   */
  bool IsTrue();

  /**
   * Returns true if this value is false.
   */
  bool IsFalse();

  /**
   * Returns true if this value is an instance of the String type.
   * See ECMA-262 8.4.
   */
  bool IsString();

  /**
   * Returns true if this value is a function.
   */
  bool IsFunction();

  /**
   * Returns true if this value is an array.
   */
  bool IsArray();

   /**
   * Returns true if this value is an object.
   */
  bool IsObject();

   /**
   * Returns true if this value is boolean.
   */
  bool IsBoolean();

   /**
   * Returns true if this value is a number.
   */
  bool IsNumber();

   /**
   * Returns true if this value is external.
   */
  bool IsExternal();

   /**
   * Returns true if this value is a 32-bit signed integer.
   */
  bool IsInt32();

  Local<Boolean> ToBoolean();
  Local<Number> ToNumber();
  Local<String> ToString();
  Local<String> ToDetailString();
  Local<Object> ToObject();
  Local<Integer> ToInteger();
  Local<Uint32> ToUint32();
  Local<Int32> ToInt32();

  /**
   * Attempts to convert a string to an array index.
   * Returns an empty handle if the conversion fails.
   */
  Local<Uint32> ToArrayIndex();

  bool BooleanValue();
  double NumberValue();
  int64_t IntegerValue();
  uint32_t Uint32Value();
  int32_t Int32Value();

  /** JS == */
  bool Equals(Handle<Value> that);
  bool StrictEquals(Handle<Value> that);
};


/**
 * The superclass of primitive values.  See ECMA-262 4.3.2.
 */
class Primitive : public Value { };


/**
 * A primitive boolean value (ECMA-262, 4.3.14).  Either the true
 * or false value.
 */
class Boolean : public Primitive {
 public:
  bool Value();
  static inline Handle<Boolean> New(bool value);
};


/**
 * A javascript string value (ECMA-262, 4.3.17).
 */
class String : public Primitive {
 public:
  int Length();

 /**
  * Write the contents of the string to an external buffer.
  * If no arguments are given, expects that buffer is large
  * enough to hold the entire string and NULL terminator. Copies
  * the contents of the string and the NULL terminator into
  * 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 bytes to copy from the string.
  * \return The number of characters copied to the buffer
  * excluding the NULL terminator.
  */
  int Write(uint16_t* buffer, int start = 0, int length = -1);  // UTF-16
  int WriteAscii(char* buffer,
                 int start = 0,
                 int length = -1);  // literally ascii

 /**
  * Returns true if the string is external
  */
  bool IsExternal();

 /**
  * Returns true if the string is both external and ascii
  */
  bool IsExternalAscii();
 /**
  * An ExternalStringResource is a wrapper around a two-byte string
  * buffer that resides outside the V8's heap. Implement an
  * ExternalStringResource to manage the life cycle of the underlying
  * buffer.
  */
  class ExternalStringResource {
   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() {}
   private:
    ExternalStringResource(const ExternalStringResource&);
    void operator=(const ExternalStringResource&);
  };

  /**
  * An ExternalAsciiStringResource is a wrapper around an ascii
  * string buffer that resides outside V8's heap. Implement an
  * ExternalAsciiStringResource to manage the life cycle of the
  * underlying buffer.
  */

  class ExternalAsciiStringResource {
   public:
    /**
     * Override the destructor to manage the life cycle of the underlying
     * buffer.
     */
    virtual ~ExternalAsciiStringResource() {}
    /** The string data from the underlying buffer.*/
    virtual const char* data() const = 0;
    /** The number of ascii characters in the string.*/
    virtual size_t length() const = 0;
   protected:
    ExternalAsciiStringResource() {}
   private:
    ExternalAsciiStringResource(const ExternalAsciiStringResource&);
    void operator=(const ExternalAsciiStringResource&);
  };

  /**
   * Get the ExternalStringResource for an external string.  Only
   * valid if IsExternal() returns true.
   */
  ExternalStringResource* GetExternalStringResource();

  /**
   * Get the ExternalAsciiStringResource for an external ascii string.
   * Only valid if IsExternalAscii() returns true.
   */
  ExternalAsciiStringResource* GetExternalAsciiStringResource();

  static String* Cast(v8::Value* obj);

  /**
   * Allocates a new string from either utf-8 encoded or ascii data.
   * The second parameter 'length' gives the buffer length.
   * If the data is utf-8 encoded, the caller must
   * be careful to supply the length parameter.
   * If it is not given, the function calls
   * 'strlen' to determine the buffer length, it might be
   * wrong if '\0' character is in the 'data'.
   */
  static Local<String> New(const char* data, int length = -1);

  /** Allocates a new string from utf16 data.*/
  static Local<String> New(const uint16_t* data, int length = -1);

  /** Creates a symbol. Returns one if it exists already.*/
  static Local<String> NewSymbol(const char* data, int length = -1);

 /**
  * Creates a new external string using the data defined in the given
  * resource. The resource is deleted when the external string is no
  * longer live on V8's heap. The caller of this function should not
  * 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(ExternalStringResource* resource);

   /**
  * Creates a new external string using the ascii data defined in the given
  * resource. The resource is deleted when the external string is no
  * longer live on V8's heap. The caller of this function should not
  * 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(ExternalAsciiStringResource* resource);

  /** Creates an undetectable string from the supplied character.*/
  static Local<String> NewUndetectable(const char* data, int length = -1);

    /** Creates an undetectable string from the supplied unsigned integer.*/
  static Local<String> NewUndetectable(const uint16_t* data, int length = -1);

  /**
   * Converts an object to an ascii string.
   * Useful if you want to print the object.
   */
  class AsciiValue {
   public:
    explicit AsciiValue(Handle<v8::Value> obj);
    ~AsciiValue();
    char* operator*() { return str_; }
   private:
    char* str_;
  };

  /**
   * Converts an object to a two-byte string.
   */
  class Value {
   public:
    explicit Value(Handle<v8::Value> obj);
    ~Value();
    uint16_t* operator*() { return str_; }
   private:
    uint16_t* str_;
  };
};


/**
 * A javascript number value (ECMA-262, 4.3.20)
 */
class Number : public Primitive {
 public:
  double Value();
  static Local<Number> New(double value);
  static Number* Cast(v8::Value* obj);
 private:
  Number();
};


/**
 * A javascript value representing a signed integer.
 */
class Integer : public Number {
 public:
  static Local<Integer> New(int32_t value);
  int64_t Value();
  static Integer* Cast(v8::Value* obj);
 private:
  Integer();
};


/**
 * A javascript value representing a 32-bit signed integer.
 */
class Int32 : public Integer {
 public:
  int32_t Value();
 private:
  Int32();
};


/**
 * A javascript value representing a 32-bit unsigned integer.
 */
class Uint32 : public Integer {
 public:
  uint32_t Value();
 private:
  Uint32();
};


/**
 * An instance of the built-in Date constructor (ECMA-262, 15.9).
 */
class Date : public Value {
 public:
  static Local<Value> New(double time);
};


enum PropertyAttribute {
  None       = 0,
  ReadOnly   = 1 << 0,
  DontEnum   = 1 << 1,
  DontDelete = 1 << 2
};

/**
 * A javascript object (ECMA-262, 4.3.3)
 */
class Object : public Value {
 public:
  bool Set(Handle<Value> key,
           Handle<Value> value,
           PropertyAttribute attribs = None);
  Local<Value> Get(Handle<Value> key);

  // TODO(1245389): Replace the type-specific versions of these
  // functions with generic ones that accept a Handle<Value> key.
  bool Has(Handle<String> key);
  bool Delete(Handle<String> key);
  bool Has(uint32_t index);
  bool Delete(uint32_t index);

  /**
   * 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();

  /**
   * 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();

  /** Gets the number of internal fields for this Object. */
  int InternalFieldCount();
  /** Gets the value in an internal field. */
  Local<Value> GetInternalField(int index);
  /** Sets the value in an internal field. */
  void SetInternalField(int index, Handle<Value> value);

  // Testers for local properties.
  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.
   */
  Handle<Value> GetRealNamedPropertyInPrototypeChain(Handle<String> key);

  /** Tests for a named lookup interceptor.*/
  bool HasNamedLookupInterceptor();

  /** Tests for an index lookup interceptor.*/
  bool HasIndexedLookupInterceptor();


  static Local<Object> New();
  static Object* Cast(Value* obj);
 private:
  Object();
};


/**
 * An instance of the built-in array constructor (ECMA-262, 15.4.2).
 */
class Array : public Object {
 public:
  uint32_t Length();

  static Local<Array> New(int length = 0);
  static Array* Cast(Value* obj);
 private:
  Array();
};


/**
 * A javascript function object (ECMA-262, 15.3).
 */
class Function : public Object {
 public:
  Local<Object> NewInstance();
  Local<Object> NewInstance(int argc, Handle<Value> argv[]);
  Local<Value> Call(Handle<Object> recv, int argc, Handle<Value> argv[]);
  void SetName(Handle<String> name);
  Handle<Value> GetName();
  static Function* Cast(Value* obj);
 private:
  Function();
};


/**
 * A javascript value that wraps a c++ void*.  This type of value is
 * mainly used to associate c++ data structures with javascript
 * objects.
 */
class External : public Value {
 public:
  static Local<External> New(void* value);
  static External* Cast(Value* obj);
  void* Value();
 private:
  External();
};


// --- T e m p l a t e s ---


/**
 * The superclass of object and function templates.
 */
class Template : public Data {
 public:
  /** Adds a property to each instance created by this template.*/
  void Set(Handle<String> name, Handle<Data> value,
           PropertyAttribute attributes = None);
  inline void Set(const char* name, Handle<Data> value);
 private:
  Template();

  friend class ObjectTemplate;
  friend class FunctionTemplate;
};


/**
 * The argument information given to function call callbacks.  This
 * class provides access to information about context of the call,
 * including the receiver, the number and values of arguments, and
 * the holder of the function.
 */
class Arguments {
 public:
  inline int Length() const;
  inline Local<Value> operator[](int i) const;
  inline Local<Function> Callee() const;
  inline Local<Object> This() const;
  inline Local<Object> Holder() const;
  inline bool IsConstructCall() const;
  inline Local<Value> Data() const;
 private:
  Arguments();
  friend class ImplementationUtilities;
  inline Arguments(Local<Value> data,
                   Local<Object> holder,
                   Local<Function> callee,
                   bool is_construct_call,
                   void** values, int length);
  Local<Value> data_;
  Local<Object> holder_;
  Local<Function> callee_;
  bool is_construct_call_;
  void** values_;
  int length_;
};


/**
 * The information passed to an accessor callback about the context
 * of the property access.
 */
class AccessorInfo {
 public:
  inline AccessorInfo(Local<Object> self,
                      Local<Value> data,
                      Local<Object> holder)
      : self_(self), data_(data), holder_(holder) { }
  inline Local<Value> Data() const;
  inline Local<Object> This() const;
  inline Local<Object> Holder() const;
 private:
  Local<Object> self_;
  Local<Value> data_;
  Local<Object> holder_;
};


typedef Handle<Value> (*InvocationCallback)(const Arguments& args);

typedef int (*LookupCallback)(Local<Object> self, Local<String> name);

/**
 * Accessor[Getter|Setter] are used as callback functions when
 * setting|getting a particular property. See objectTemplate::SetAccessor.
 */
typedef Handle<Value> (*AccessorGetter)(Local<String> property,
                                        const AccessorInfo& info);


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


/**
 * NamedProperty[Getter|Setter] are used as interceptors on object.
 * See ObjectTemplate::SetNamedPropertyHandler.
 */
typedef Handle<Value> (*NamedPropertyGetter)(Local<String> property,
                                             const AccessorInfo& info);


/**
 * Returns the value if the setter intercepts the request.
 * Otherwise, returns an empty handle.
 */
typedef Handle<Value> (*NamedPropertySetter)(Local<String> property,
                                             Local<Value> value,
                                             const AccessorInfo& info);


/**
 * Returns a non-empty handle if the interceptor intercepts the request.
 * The result is true to indicate the property is found.
 */
typedef Handle<Boolean> (*NamedPropertyQuery)(Local<String> property,
                                              const AccessorInfo& info);


/**
 * Returns a non-empty handle if the deleter intercepts the request.
 * Otherwise, the return value is the value of deleted expression.
 */
typedef Handle<Boolean> (*NamedPropertyDeleter)(Local<String> property,
                                                const AccessorInfo& info);

/**
 * TODO(758124): Add documentation?
 */
typedef Handle<Array> (*NamedPropertyEnumerator)(const AccessorInfo& info);

/**
 * TODO(758124): Add documentation?
 */
typedef Handle<Value> (*IndexedPropertyGetter)(uint32_t index,
                                               const AccessorInfo& info);


/**
 * Returns the value if the setter intercepts the request.
 * Otherwise, returns an empty handle.
 */
typedef Handle<Value> (*IndexedPropertySetter)(uint32_t index,
                                               Local<Value> value,
                                               const AccessorInfo& info);


/**
 * Returns a non-empty handle if the interceptor intercepts the request.
 * The result is true to indicate the property is found.
 */
typedef Handle<Boolean> (*IndexedPropertyQuery)(uint32_t index,
                                                const AccessorInfo& info);

/**
 * Returns a non-empty handle if the deleter intercepts the request.
 * Otherwise, the return value is the value of deleted expression.
 */
typedef Handle<Boolean> (*IndexedPropertyDeleter)(uint32_t index,
                                                  const AccessorInfo& info);


typedef Handle<Array> (*IndexedPropertyEnumerator)(const AccessorInfo& info);


/**
 * TODO(758124): Clarify documentation? Determines whether host
 * objects can read or write an accessor? (What does the default
 * allow? Both or neither?)  If a host object needs access check and
 * the check failed, some properties (accessors created by API) are
 * still accessible.  Such properties have AccessControl to allow read
 * or write.
 */
enum AccessControl {
  DEFAULT         = 0,
  ALL_CAN_READ    = 1,
  ALL_CAN_WRITE   = 2
};


/**
 * Undocumented security features.
 */
enum AccessType {
  ACCESS_GET,
  ACCESS_SET,
  ACCESS_HAS,
  ACCESS_DELETE,
  ACCESS_KEYS
};

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

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


/**
 * TODO(758124): Make sure this documentation is up to date.
 *
 * A FunctionTemplate is used to create functions at runtime. There can only be
 * ONE function created in an environment.
 *
 * A FunctionTemplate can have properties, these properties are added to the
 * function object which it is created.
 *
 * A FunctionTemplate has a corresponding instance template which is used to
 * create object instances when the function 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.
 *
 * Following example illustrates relationship between FunctionTemplate and
 * various pieces:
 *
 *    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();
 *
 * Let's use "function" as the JS variable name of the function object
 * and "instance" for the instance object created above, the following
 * JavaScript statements hold:
 *
 *   func_property in function == true
 *   function.func_property == 1
 *
 *   function.prototype.proto_method() invokes 'callback'
 *   function.prototype.proto_const == 2
 *
 *   instance instanceof function == true
 *   instance.instance_accessor calls InstanceAccessorCallback
 *   instance.instance_property == 3
 *
 *
 * Inheritance:
 *
 * A FunctionTemplate can inherit from another one by calling Inherit method.
 * Following graph illustrates the semantic of inheritance:
 *
 *  FunctionTemplate Parent  -> Parent() . prototype -> { }
 *    ^                                                  ^
 *    | Inherit(Parent)                                  | .__proto__
 *    |                                                  |
 *  FunctionTemplate Child   -> Child()  . prototype -> { }
 *
 * A FunctionTemplate 'Child' inherits from 'Parent', the prototype object
 * of Child() function has __proto__ pointing to Parent() function's prototype
 * object. An instance of Child function has all properties on parents'
 * instance templates.
 *
 * Let Parent be the FunctionTemplate initialized in previous section and
 * create a Child function template by:
 *
 *   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();
 *
 * The following JS code holds:
 *   child_func.prototype.__proto__ == function.prototype;
 *   child_instance.instance_accessor calls InstanceAccessorCallback
 *   child_instance.instance_property == 3;
 */
class FunctionTemplate : public Template {
 public:
  /** Creates a function template.*/
  static Local<FunctionTemplate> New(InvocationCallback callback = 0,
                                     Handle<Value> data = Handle<Value>(),
                                     Handle<Signature> signature =
                                         Handle<Signature>());
  /** Returns the unique function instance in the current execution context.*/
  Local<Function> GetFunction();

  void SetCallHandler(InvocationCallback callback,
                      Handle<Value> data = Handle<Value>());
  void SetLookupHandler(LookupCallback handler);

  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();

  void SetClassName(Handle<String> name);

  /**
   * Determines whether the __proto__ accessor ignores instances of the function template.
   * 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.
   * TODO(758124): What does "not ignored" mean?
   */
  void SetHiddenPrototype(bool value);

  /**
   * Returns true if the given object is an instance of this function template.
   */
  bool HasInstance(Handle<Value> object);

 private:
  FunctionTemplate();
  void AddInstancePropertyAccessor(Handle<String> name,
                                   AccessorGetter getter,
                                   AccessorSetter setter,
                                   Handle<Value> data,
                                   AccessControl settings,
                                   PropertyAttribute attributes);
  void SetNamedInstancePropertyHandler(NamedPropertyGetter getter,
                                       NamedPropertySetter setter,
                                       NamedPropertyQuery query,
                                       NamedPropertyDeleter remover,
                                       NamedPropertyEnumerator enumerator,
                                       Handle<Value> data);
  void SetIndexedInstancePropertyHandler(IndexedPropertyGetter getter,
                                         IndexedPropertySetter setter,
                                         IndexedPropertyQuery query,
                                         IndexedPropertyDeleter remover,
                                         IndexedPropertyEnumerator enumerator,
                                         Handle<Value> data);
  void SetInstanceCallAsFunctionHandler(InvocationCallback callback,
                                        Handle<Value> data);

  friend class Context;
  friend class ObjectTemplate;
};


/**
 * ObjectTemplate: (TODO(758124): Add comments.)
 */
class ObjectTemplate : public Template {
 public:
  static Local<ObjectTemplate> New();
  /** Creates a new instance of this template.*/
  Local<Object> NewInstance();

  /**
   * Sets an accessor on the object template.
   * /param name (TODO(758124): Describe)
   * /param getter (TODO(758124): Describe)
   * /param setter (TODO(758124): Describe)
   * /param data ((TODO(758124): Describe)
   * /param settings settings must be one of:
   *   DEFAULT = 0, ALL_CAN_READ = 1, or ALL_CAN_WRITE = 2
   * /param attribute (TODO(758124): Describe)
   */
  void SetAccessor(Handle<String> name,
                   AccessorGetter getter,
                   AccessorSetter setter = 0,
                   Handle<Value> data = Handle<Value>(),
                   AccessControl settings = DEFAULT,
                   PropertyAttribute attribute = None);

  /**
   * Sets a named property handler on the object template.
   * /param getter (TODO(758124): Describe)
   * /param setter (TODO(758124): Describe)
   * /param query (TODO(758124): Describe)
   * /param deleter (TODO(758124): Describe)
   * /param enumerator (TODO(758124): Describe)
   * /param data (TODO(758124): Describe)
   */
  void SetNamedPropertyHandler(NamedPropertyGetter getter,
                               NamedPropertySetter setter = 0,
                               NamedPropertyQuery query = 0,
                               NamedPropertyDeleter deleter = 0,
                               NamedPropertyEnumerator enumerator = 0,
                               Handle<Value> data = Handle<Value>());

  /**
   * Sets an indexed property handler on the object template.
   * /param getter (TODO(758124): Describe)
   * /param setter (TODO(758124): Describe)
   * /param query (TODO(758124): Describe)
   * /param deleter (TODO(758124): Describe)
   * /param enumerator (TODO(758124): Describe)
   * /param data (TODO(758124): Describe)
   */
  void SetIndexedPropertyHandler(IndexedPropertyGetter getter,
                                 IndexedPropertySetter setter = 0,
                                 IndexedPropertyQuery query = 0,
                                 IndexedPropertyDeleter deleter = 0,
                                 IndexedPropertyEnumerator enumerator = 0,
                                 Handle<Value> data = Handle<Value>());
  /**
   * 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(InvocationCallback callback,
                                Handle<Value> data = Handle<Value>());

  /** Make object instances of the template as undetectable.*/
  void MarkAsUndetectable();

  /** TODO(758124): Clarify documentation: Object instances of the
   * template need access check.*/
  void SetAccessCheckCallbacks(NamedSecurityCallback named_handler,
                               IndexedSecurityCallback indexed_handler,
                               Handle<Value> data = Handle<Value>());

  /**
   * 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(Handle<FunctionTemplate> constructor);
  friend class FunctionTemplate;
};


/**
 * A function signature which specifies which receivers and arguments
 * in can legally be called with.
 */
class Signature : public Data {
 public:
  static Local<Signature> New(Handle<FunctionTemplate> receiver =
                                  Handle<FunctionTemplate>(),
                              int argc = 0,
                              Handle<FunctionTemplate> argv[] = 0);
 private:
  Signature();
};


/**
 * A utility for determining the type of objects based on which
 * template they were constructed from.
 */
class 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();
};


// --- E x t e n s i o n s ---


/**
 * Ignore
 */
class Extension {
 public:
  Extension(const char* name,
            const char* source = 0,
            int dep_count = 0,
            const char** deps = 0);
  virtual ~Extension() { }
  virtual v8::Handle<v8::FunctionTemplate>
      GetNativeFunction(v8::Handle<v8::String> name) {
    return v8::Handle<v8::FunctionTemplate>();
  }

  const char* name() { return name_; }
  const char* source() { 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_;
  const char* source_;
  int dep_count_;
  const char** deps_;
  bool auto_enable_;
};


void RegisterExtension(Extension* extension);


/**
 * Ignore
 */
class DeclareExtension {
 public:
  inline DeclareExtension(Extension* extension) {
    RegisterExtension(extension);
  }
};


// --- S t a t i c s ---


Handle<Primitive> Undefined();
Handle<Primitive> Null();
Handle<Boolean> True();
Handle<Boolean> False();


/**
 * A set of constraints that specifies the limits of the runtime's
 * memory use.
 */
class ResourceConstraints {
 public:
  ResourceConstraints();
  int max_young_space_size() { return max_young_space_size_; }
  void set_max_young_space_size(int value) { max_young_space_size_ = value; }
  int max_old_space_size() { return max_old_space_size_; }
  void set_max_old_space_size(int value) { max_old_space_size_ = value; }
  uint32_t* stack_limit() { return stack_limit_; }
  void set_stack_limit(uint32_t* value) { stack_limit_ = value; }
 private:
  int max_young_space_size_;
  int max_old_space_size_;
  uint32_t* stack_limit_;
};


bool SetResourceConstraints(ResourceConstraints* constraints);


// --- E x c e p t i o n s ---


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


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


/**
 * 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.
 */
Handle<Value> ThrowException(Handle<Value> exception);

/**
 * Create new error objects by calling the corresponding error object
 * constructor with the message.
 */
class 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);
};


/**
 * Ignore
 */
struct VersionInfo {
  int major, minor, build_major, build_minor, revision;
};

// --- C o u n t e r s  C a l l b a c k s

typedef int* (*CounterLookupCallback)(const wchar_t* name);

// --- F a i l e d A c c e s s C h e c k C a l l b a c k ---
typedef void (*FailedAccessCheckCallback)(Local<Object> target,
                                          AccessType type,
                                          Local<Value> data);

// --- G a r b a g e C o l l e c t i o n  C a l l b a c k s

/**
 * Applications can register a callback function which is called
 * before and after a major Garbage Collection.
 * Allocations are not allowed in the callback function, you therefore.
 * cannot manipulate objects (set or delete properties for example)
 * since it is likely such operations will result in the allocation of objects.
 */
typedef void (*GCCallback)();


//  --- C o n t e x t  G e n e r a t o r

/**
 * Applications must provide a callback function which is called to generate
 * a context if a context wasn't deserialized from the snapshot.
 */

typedef Persistent<Context> (*ContextGenerator)();


/**
 * Container class for static utility functions.
 */
class V8 {
 public:
  static void SetFatalErrorHandler(FatalErrorCallback that);

  // TODO(758124): Clarify documentation: Prevent top level from
  // calling V8::FatalProcessOutOfMemory if HasOutOfMemoryException();
  static void IgnoreOutOfMemoryException();

  // Check if V8 is dead.
  static bool IsDead();

  /**
   * TODO(758124): Clarify documentation - what is the "ones" in
   * "existing ones": Adds a message listener, does not overwrite any
   * existing ones with the same callback function.
   */
  static bool AddMessageListener(MessageCallback that,
                                 Handle<Value> data = Handle<Value>());

  /**
   * Remove all message listeners from the specified callback function.
   */
  static void RemoveMessageListeners(MessageCallback that);

  /**
   * Sets v8 flags from a string.
   * TODO(758124): Describe flags?
   */
  static void SetFlagsFromString(const char* str, int length);

  /** Sets the version fields in the given VersionInfo struct.*/
  static void GetVersion(VersionInfo* info);

  /**
   * Enables the host application to provide a mechanism for recording
   * statistics counters.
   */
  static void SetCounterFunction(CounterLookupCallback);

  /**
   * Enables the computation of a sliding window of states. The sliding
   * window information is recorded in statistics counters.
   */
  static void EnableSlidingStateWindow();

  /** Callback function for reporting failed access checks.*/
  static void SetFailedAccessCheckCallbackFunction(FailedAccessCheckCallback);

  /**
   * Enables the host application to receive a notification before a major GC.
   * Allocations are not allowed in the callback function, you therefore
   * cannot manipulate objects (set or delete properties for example)
   * since it is likely such operations will result in the allocation of objects.
   */
  static void SetGlobalGCPrologueCallback(GCCallback);

  /**
   * Enables the host application to receive a notification after a major GC.
   * (TODO(758124): is the following true for this one too?)
   * Allocations are not allowed in the callback function, you therefore
   * cannot manipulate objects (set or delete properties for example)
   * since it is likely such operations will result in the allocation of objects.
   */
  static void SetGlobalGCEpilogueCallback(GCCallback);

  /**
   * 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 GC, object groups are removed. It is intended to be used
   * in the before-GC callback function to simulate DOM tree connections
   * among JS wrapper objects.
   */
  static void AddObjectToGroup(void* id, Persistent<Object> obj);

  /**
   * Initializes from snapshot if possible. Otherwise, attempts to initialize
   * from scratch.
   */
  static bool Initialize();

 private:
  V8();

  static void** GlobalizeReference(void** handle);
  static void DisposeGlobal(void** global_handle);
  static void MakeWeak(void** global_handle, void* data, WeakReferenceCallback);
  static void ClearWeak(void** global_handle);
  static bool IsGlobalNearDeath(void** global_handle);
  static bool IsGlobalWeak(void** global_handle);

  template <class T> friend class Handle;
  template <class T> friend class Local;
  template <class T> friend class Persistent;
  friend class Context;
};


/**
 * An external exception handler.
 */
class TryCatch {
 public:

  /**
   * Creates a new try/catch block and registers it with v8.
   */
  TryCatch();

  /**
   * Unregisters and deletes this try/catch block.
   */
  ~TryCatch();

  /**
   * Returns true if an exception has been caught by this try/catch block.
   */
  bool HasCaught();

  /**
   * 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();

  /**
   * Clears any exceptions that may have been caught by this try/catch block.
   * After this method has been called, HasCaught() will return false.
   *
   * 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();

  void SetVerbose(bool value);

 public:
  TryCatch* next_;
  void* exception_;
  bool is_verbose_;
};


// --- C o n t e x t ---


/**
 * Ignore
 */
class ExtensionConfiguration {
 public:
  ExtensionConfiguration(int name_count, const char* names[])
      : name_count_(name_count), names_(names) { }
 private:
  friend class ImplementationUtilities;
  int name_count_;
  const char** names_;
};


/**
 * A sandboxed execution context with its own set of built-in objects
 * and functions.
 */
class Context {
 public:
  Local<Object> Global();

  static Persistent<Context> New(ExtensionConfiguration* extensions = 0,
                                 Handle<ObjectTemplate> global_template =
                                     Handle<ObjectTemplate>(),
                                 Handle<Value> global_object = Handle<Value>());

  /** Returns the context that is on the top of the stack.*/
  static Local<Context> Current();

  /** Returns the security context used to start JS execution.*/
  static Local<Context> GetSecurityContext();

  /**
   * Sets the security token for the context.  To access an object in
   * another context, the security tokens must match.
   */
  void SetSecurityToken(Handle<Value> token);

  /** Returns the security token of this context.*/
  Handle<Value> GetSecurityToken();

  void Enter();
  void Exit();

  /** Returns true if the context has experienced an out of memory situation.*/
  bool HasOutOfMemoryException();

  /** Returns true if called from within a context.*/
  static bool InContext();

  /** Returns true if called from within a security context.*/
  static bool InSecurityContext();

  /**
   * Stack-allocated class which sets the execution context for all
   * operations executed within a local scope.
   */
  class Scope {
   public:
    inline Scope(Handle<Context> context) : context_(context) {
      context_->Enter();
    }
    inline ~Scope() { context_->Exit(); }
   private:
    Handle<Context> context_;
  };

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


/**
 * Multiple threads in V8 are allowed, but only one thread at a time is
 * allowed to use V8.  The definition of using V8' includes accessing
 * handles or holding onto object pointers obtained from V8 handles.
 * It is up to the user of V8 to ensure (perhaps with locking) that
 * this constraint is not violated.
 *
 * If you wish to start using V8 in a thread you can do this by constructing
 * a v8::Locker object.  After the code using V8 has completed for the
 * current thread you can call the destructor.  This can be combined
 * with C++ scope-based construction as follows:
 *
 * ...
 * {
 *   v8::Locker locker;
 *   ...
 *   // Code using V8 goes here.
 *   ...
 * } // Destructor called here
 *
 * If you wish to stop using V8 in a thread A you can do this by either
 * by destroying the v8::Locker object as above or by constructing a
 * v8::Unlocker object:
 *
 * {
 *   v8::Unlocker unlocker;
 *   ...
 *   // Code not using V8 goes here while V8 can run in another thread.
 *   ...
 * } // Destructor called here.
 *
 * 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.  That is, 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. eg.:
 *
 * // V8 not locked.
 * {
 *   v8::Locker locker;
 *   // V8 locked.
 *   {
 *     v8::Locker another_locker;
 *     // V8 still locked (2 levels).
 *     {
 *       v8::Unlocker unlocker;
 *       // V8 not locked.
 *     }
 *     // V8 locked again (2 levels).
 *   }
 *   // V8 still locked (1 level).
 * }
 * // V8 Now no longer locked.
 */
class Unlocker {
 public:
  Unlocker();
  ~Unlocker();
};


class Locker {
 public:
  Locker();
  ~Locker();
#ifdef DEBUG
  static void AssertIsLocked();
#else
  static inline void AssertIsLocked() { }
#endif
  /*
   * Fires a timer every n ms that will switch between
   * multiple threads that are in contention for the V8 lock.
   */
  static void StartPreemption(int every_n_ms);
  static void StopPreemption();
 private:
  bool has_lock_;
  bool top_level_;
};



// --- I m p l e m e n t a t i o n ---

template <class T>
Handle<T>::Handle() : val_(0) { }


template <class T>
Local<T>::Local() : Handle<T>() { }


template <class T>
Local<T> Local<T>::New(Handle<T> that) {
  if (that.IsEmpty()) return Local<T>();
  void** p = reinterpret_cast<void**>(*that);
  return Local<T>(reinterpret_cast<T*>(HandleScope::CreateHandle(*p)));
}


template <class T>
Persistent<T> Persistent<T>::New(Handle<T> that) {
  if (that.IsEmpty()) return Persistent<T>();
  void** p = reinterpret_cast<void**>(*that);
  return Persistent<T>(reinterpret_cast<T*>(V8::GlobalizeReference(p)));
}


template <class T>
bool Persistent<T>::IsNearDeath() {
  if (this->IsEmpty()) return false;
  return V8::IsGlobalNearDeath(reinterpret_cast<void**>(**this));
}


template <class T>
bool Persistent<T>::IsWeak() {
  if (this->IsEmpty()) return false;
  return V8::IsGlobalWeak(reinterpret_cast<void**>(**this));
}


template <class T>
void Persistent<T>::Dispose() {
  if (this->IsEmpty()) return;
  V8::DisposeGlobal(reinterpret_cast<void**>(**this));
}


template <class T>
Persistent<T>::Persistent() : Handle<T>() { }

template <class T>
void Persistent<T>::MakeWeak(void* parameters, WeakReferenceCallback callback) {
  V8::MakeWeak(reinterpret_cast<void**>(**this), parameters, callback);
}

template <class T>
void Persistent<T>::ClearWeak() {
  V8::ClearWeak(reinterpret_cast<void**>(**this));
}

template <class T>
T* Handle<T>::operator->() {
  return val_;
}


template <class T>
T* Handle<T>::operator*() {
  return val_;
}


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


Local<Function> Arguments::Callee() const {
  return callee_;
}


Local<Object> Arguments::This() const {
  return Local<Object>(reinterpret_cast<Object*>(values_ + 1));
}


Local<Object> Arguments::Holder() const {
  return holder_;
}


Local<Value> Arguments::Data() const {
  return data_;
}


bool Arguments::IsConstructCall() const {
  return is_construct_call_;
}


int Arguments::Length() const {
  return length_;
}


Local<Value> AccessorInfo::Data() const {
  return data_;
}


Local<Object> AccessorInfo::This() const {
  return self_;
}


Local<Object> AccessorInfo::Holder() const {
  return holder_;
}


template <class T>
Local<T> HandleScope::Close(Handle<T> value) {
  void** after = RawClose(reinterpret_cast<void**>(*value));
  return Local<T>(reinterpret_cast<T*>(after));
}

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


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


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


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


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


/**
 * \example evaluator.cc
 * A simple evaluator that takes a list of expressions on the
 * command-line and executes them.
 */


/**
 * \example process.cc
 */


}  // namespace v8


#undef EXPORT
#undef TYPE_CHECK


#endif  // _V8