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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_API_H_
#define V8_API_H_
#include "src/v8.h"
#include "include/v8-testing.h"
#include "src/contexts.h"
#include "src/factory.h"
#include "src/isolate.h"
#include "src/list-inl.h"
namespace v8 {
// Constants used in the implementation of the API. The most natural thing
// would usually be to place these with the classes that use them, but
// we want to keep them out of v8.h because it is an externally
// visible file.
class Consts {
enum TemplateType {
// Utilities for working with neander-objects, primitive
// env-independent JSObjects used by the api.
class NeanderObject {
explicit NeanderObject(v8::internal::Isolate* isolate, int size);
explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
explicit inline NeanderObject(v8::internal::Object* obj);
inline v8::internal::Object* get(int index);
inline void set(int index, v8::internal::Object* value);
inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
int size();
v8::internal::Handle<v8::internal::JSObject> value_;
// Utilities for working with neander-arrays, a simple extensible
// array abstraction built on neander-objects.
class NeanderArray {
explicit NeanderArray(v8::internal::Isolate* isolate);
explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
inline v8::internal::Handle<v8::internal::JSObject> value() {
return obj_.value();
void add(internal::Isolate* isolate,
v8::internal::Handle<v8::internal::Object> value);
int length();
v8::internal::Object* get(int index);
// Change the value at an index to undefined value. If the index is
// out of bounds, the request is ignored. Returns the old value.
void set(int index, v8::internal::Object* value);
NeanderObject obj_;
NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
: value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
NeanderObject::NeanderObject(v8::internal::Object* obj)
: value_(v8::internal::Handle<v8::internal::JSObject>(
v8::internal::JSObject::cast(obj))) { }
NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
: obj_(obj) { }
v8::internal::Object* NeanderObject::get(int offset) {
return v8::internal::FixedArray::cast(value()->elements())->get(offset);
void NeanderObject::set(int offset, v8::internal::Object* value) {
v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
template <typename T> inline T ToCData(v8::internal::Object* obj) {
STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
return reinterpret_cast<T>(
template <typename T>
inline v8::internal::Handle<v8::internal::Object> FromCData(
v8::internal::Isolate* isolate, T obj) {
STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
return isolate->factory()->NewForeign(
class ApiFunction {
explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
v8::internal::Address address() { return addr_; }
v8::internal::Address addr_;
class RegisteredExtension {
explicit RegisteredExtension(Extension* extension);
static void Register(RegisteredExtension* that);
static void UnregisterAll();
Extension* extension() { return extension_; }
RegisteredExtension* next() { return next_; }
static RegisteredExtension* first_extension() { return first_extension_; }
Extension* extension_;
RegisteredExtension* next_;
static RegisteredExtension* first_extension_;
V(Template, TemplateInfo) \
V(FunctionTemplate, FunctionTemplateInfo) \
V(ObjectTemplate, ObjectTemplateInfo) \
V(Signature, SignatureInfo) \
V(AccessorSignature, FunctionTemplateInfo) \
V(TypeSwitch, TypeSwitchInfo) \
V(Data, Object) \
V(RegExp, JSRegExp) \
V(Object, JSObject) \
V(Array, JSArray) \
V(ArrayBuffer, JSArrayBuffer) \
V(ArrayBufferView, JSArrayBufferView) \
V(TypedArray, JSTypedArray) \
V(Uint8Array, JSTypedArray) \
V(Uint8ClampedArray, JSTypedArray) \
V(Int8Array, JSTypedArray) \
V(Uint16Array, JSTypedArray) \
V(Int16Array, JSTypedArray) \
V(Uint32Array, JSTypedArray) \
V(Int32Array, JSTypedArray) \
V(Float32Array, JSTypedArray) \
V(Float64Array, JSTypedArray) \
V(DataView, JSDataView) \
V(Name, Name) \
V(String, String) \
V(Symbol, Symbol) \
V(Script, JSFunction) \
V(UnboundScript, SharedFunctionInfo) \
V(Function, JSFunction) \
V(Message, JSMessageObject) \
V(Context, Context) \
V(External, Object) \
V(StackTrace, JSArray) \
V(StackFrame, JSObject) \
V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
class Utils {
static inline bool ApiCheck(bool condition,
const char* location,
const char* message) {
if (!condition) Utils::ReportApiFailure(location, message);
return condition;
static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
static inline Local<Context> ToLocal(
v8::internal::Handle<v8::internal::Context> obj);
static inline Local<Value> ToLocal(
v8::internal::Handle<v8::internal::Object> obj);
static inline Local<Function> ToLocal(
v8::internal::Handle<v8::internal::JSFunction> obj);
static inline Local<Name> ToLocal(
v8::internal::Handle<v8::internal::Name> obj);
static inline Local<String> ToLocal(
v8::internal::Handle<v8::internal::String> obj);
static inline Local<Symbol> ToLocal(
v8::internal::Handle<v8::internal::Symbol> obj);
static inline Local<RegExp> ToLocal(
v8::internal::Handle<v8::internal::JSRegExp> obj);
static inline Local<Object> ToLocal(
v8::internal::Handle<v8::internal::JSObject> obj);
static inline Local<Array> ToLocal(
v8::internal::Handle<v8::internal::JSArray> obj);
static inline Local<ArrayBuffer> ToLocal(
v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
static inline Local<ArrayBufferView> ToLocal(
v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
static inline Local<DataView> ToLocal(
v8::internal::Handle<v8::internal::JSDataView> obj);
static inline Local<TypedArray> ToLocal(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Uint8Array> ToLocalUint8Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Int8Array> ToLocalInt8Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Uint16Array> ToLocalUint16Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Int16Array> ToLocalInt16Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Uint32Array> ToLocalUint32Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Int32Array> ToLocalInt32Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Float32Array> ToLocalFloat32Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Float64Array> ToLocalFloat64Array(
v8::internal::Handle<v8::internal::JSTypedArray> obj);
static inline Local<Message> MessageToLocal(
v8::internal::Handle<v8::internal::Object> obj);
static inline Local<Promise> PromiseToLocal(
v8::internal::Handle<v8::internal::JSObject> obj);
static inline Local<StackTrace> StackTraceToLocal(
v8::internal::Handle<v8::internal::JSArray> obj);
static inline Local<StackFrame> StackFrameToLocal(
v8::internal::Handle<v8::internal::JSObject> obj);
static inline Local<Number> NumberToLocal(
v8::internal::Handle<v8::internal::Object> obj);
static inline Local<Integer> IntegerToLocal(
v8::internal::Handle<v8::internal::Object> obj);
static inline Local<Uint32> Uint32ToLocal(
v8::internal::Handle<v8::internal::Object> obj);
static inline Local<FunctionTemplate> ToLocal(
v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
static inline Local<ObjectTemplate> ToLocal(
v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
static inline Local<Signature> ToLocal(
v8::internal::Handle<v8::internal::SignatureInfo> obj);
static inline Local<AccessorSignature> AccessorSignatureToLocal(
v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
static inline Local<TypeSwitch> ToLocal(
v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
static inline Local<External> ExternalToLocal(
v8::internal::Handle<v8::internal::JSObject> obj);
static inline Local<DeclaredAccessorDescriptor> ToLocal(
v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);
#define DECLARE_OPEN_HANDLE(From, To) \
static inline v8::internal::Handle<v8::internal::To> \
OpenHandle(const From* that, bool allow_empty_handle = false);
template<class From, class To>
static inline Local<To> Convert(v8::internal::Handle<From> obj) {
DCHECK(obj.is_null() || !obj->IsTheHole());
return Local<To>(reinterpret_cast<To*>(obj.location()));
template <class T>
static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
const v8::Persistent<T>& persistent) {
return v8::internal::Handle<v8::internal::Object>(
template <class T>
static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
v8::Persistent<T>* persistent) {
return OpenPersistent(*persistent);
template <class From, class To>
static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
return OpenHandle(*handle);
static void ReportApiFailure(const char* location, const char* message);
template <class T>
v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
v8::EscapableHandleScope* scope) {
v8::internal::Handle<T> handle;
if (!is_null()) {
handle = *this;
return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
template <class T>
inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
return reinterpret_cast<T*>(obj.location());
template <class T>
inline v8::Local<T> ToApiHandle(
v8::internal::Handle<v8::internal::Object> obj) {
return Utils::Convert<v8::internal::Object, T>(obj);
// Implementations of ToLocal
#define MAKE_TO_LOCAL(Name, From, To) \
Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
return Convert<v8::internal::From, v8::To>(obj); \
#define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size) \
Local<v8::Type##Array> Utils::ToLocal##Type##Array( \
v8::internal::Handle<v8::internal::JSTypedArray> obj) { \
DCHECK(obj->type() == kExternal##Type##Array); \
return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
MAKE_TO_LOCAL(ToLocal, Context, Context)
MAKE_TO_LOCAL(ToLocal, Object, Value)
MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
MAKE_TO_LOCAL(ToLocal, Name, Name)
MAKE_TO_LOCAL(ToLocal, String, String)
MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
MAKE_TO_LOCAL(ToLocal, JSObject, Object)
MAKE_TO_LOCAL(ToLocal, JSArray, Array)
MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
MAKE_TO_LOCAL(MessageToLocal, Object, Message)
MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
MAKE_TO_LOCAL(NumberToLocal, Object, Number)
MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
// Implementations of OpenHandle
#define MAKE_OPEN_HANDLE(From, To) \
v8::internal::Handle<v8::internal::To> Utils::OpenHandle( \
const v8::From* that, bool allow_empty_handle) { \
EXTRA_CHECK(allow_empty_handle || that != NULL); \
EXTRA_CHECK(that == NULL || \
(*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
return v8::internal::Handle<v8::internal::To>( \
reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
namespace internal {
// Tracks string usage to help make better decisions when
// externalizing strings.
// Implementation note: internally this class only tracks fresh
// strings and keeps a single use counter for them.
class StringTracker {
// Records that the given string's characters were copied to some
// external buffer. If this happens often we should honor
// externalization requests for the string.
void RecordWrite(Handle<String> string) {
Address address = reinterpret_cast<Address>(*string);
Address top = isolate_->heap()->NewSpaceTop();
if (IsFreshString(address, top)) {
// Estimates freshness and use frequency of the given string based
// on how close it is to the new space top and the recorded usage
// history.
inline bool IsFreshUnusedString(Handle<String> string) {
Address address = reinterpret_cast<Address>(*string);
Address top = isolate_->heap()->NewSpaceTop();
return IsFreshString(address, top) && IsUseCountLow(top);
StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
static inline bool IsFreshString(Address string, Address top) {
return top - kFreshnessLimit <= string && string <= top;
inline bool IsUseCountLow(Address top) {
if (last_top_ != top) return true;
return use_count_ < kUseLimit;
inline void IncrementUseCount(Address top) {
if (last_top_ != top) {
use_count_ = 0;
last_top_ = top;
// Single use counter shared by all fresh strings.
int use_count_;
// Last new space top when the use count above was valid.
Address last_top_;
Isolate* isolate_;
// How close to the new space top a fresh string has to be.
static const int kFreshnessLimit = 1024;
// The number of uses required to consider a string useful.
static const int kUseLimit = 32;
friend class Isolate;
class DeferredHandles {
DeferredHandles(Object** first_block_limit, Isolate* isolate)
: next_(NULL),
isolate_(isolate) {
void Iterate(ObjectVisitor* v);
List<Object**> blocks_;
DeferredHandles* next_;
DeferredHandles* previous_;
Object** first_block_limit_;
Isolate* isolate_;
friend class HandleScopeImplementer;
friend class Isolate;
// This class is here in order to be able to declare it a friend of
// HandleScope. Moving these methods to be members of HandleScope would be
// neat in some ways, but it would expose internal implementation details in
// our public header file, which is undesirable.
// An isolate has a single instance of this class to hold the current thread's
// data. In multithreaded V8 programs this data is copied in and out of storage
// so that the currently executing thread always has its own copy of this
// data.
class HandleScopeImplementer {
explicit HandleScopeImplementer(Isolate* isolate)
: isolate_(isolate),
last_handle_before_deferred_block_(NULL) { }
~HandleScopeImplementer() {
// Threading support for handle data.
static int ArchiveSpacePerThread();
char* RestoreThread(char* from);
char* ArchiveThread(char* to);
void FreeThreadResources();
// Garbage collection support.
void Iterate(v8::internal::ObjectVisitor* v);
static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
inline internal::Object** GetSpareOrNewBlock();
inline void DeleteExtensions(internal::Object** prev_limit);
inline void IncrementCallDepth() {call_depth_++;}
inline void DecrementCallDepth() {call_depth_--;}
inline bool CallDepthIsZero() { return call_depth_ == 0; }
inline void EnterContext(Handle<Context> context);
inline void LeaveContext();
inline bool LastEnteredContextWas(Handle<Context> context);
// Returns the last entered context or an empty handle if no
// contexts have been entered.
inline Handle<Context> LastEnteredContext();
inline void SaveContext(Context* context);
inline Context* RestoreContext();
inline bool HasSavedContexts();
inline List<internal::Object**>* blocks() { return &blocks_; }
Isolate* isolate() const { return isolate_; }
void ReturnBlock(Object** block) {
DCHECK(block != NULL);
if (spare_ != NULL) DeleteArray(spare_);
spare_ = block;
void ResetAfterArchive() {
spare_ = NULL;
last_handle_before_deferred_block_ = NULL;
call_depth_ = 0;
void Free() {
DCHECK(blocks_.length() == 0);
DCHECK(entered_contexts_.length() == 0);
DCHECK(saved_contexts_.length() == 0);
if (spare_ != NULL) {
spare_ = NULL;
DCHECK(call_depth_ == 0);
void BeginDeferredScope();
DeferredHandles* Detach(Object** prev_limit);
Isolate* isolate_;
List<internal::Object**> blocks_;
// Used as a stack to keep track of entered contexts.
List<Context*> entered_contexts_;
// Used as a stack to keep track of saved contexts.
List<Context*> saved_contexts_;
Object** spare_;
int call_depth_;
Object** last_handle_before_deferred_block_;
// This is only used for threading support.
HandleScopeData handle_scope_data_;
void IterateThis(ObjectVisitor* v);
char* RestoreThreadHelper(char* from);
char* ArchiveThreadHelper(char* to);
friend class DeferredHandles;
friend class DeferredHandleScope;
const int kHandleBlockSize = v8::internal::KB - 2; // fit in one page
void HandleScopeImplementer::SaveContext(Context* context) {
Context* HandleScopeImplementer::RestoreContext() {
return saved_contexts_.RemoveLast();
bool HandleScopeImplementer::HasSavedContexts() {
return !saved_contexts_.is_empty();
void HandleScopeImplementer::EnterContext(Handle<Context> context) {
void HandleScopeImplementer::LeaveContext() {
bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
Handle<Context> HandleScopeImplementer::LastEnteredContext() {
if (entered_contexts_.is_empty()) return Handle<Context>::null();
return Handle<Context>(entered_contexts_.last());
// If there's a spare block, use it for growing the current scope.
internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
internal::Object** block = (spare_ != NULL) ?
spare_ :
spare_ = NULL;
return block;
void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
while (!blocks_.is_empty()) {
internal::Object** block_start = blocks_.last();
internal::Object** block_limit = block_start + kHandleBlockSize;
#ifdef DEBUG
// SealHandleScope may make the prev_limit to point inside the block.
if (block_start <= prev_limit && prev_limit <= block_limit) {
internal::HandleScope::ZapRange(prev_limit, block_limit);
if (prev_limit == block_limit) break;
internal::HandleScope::ZapRange(block_start, block_limit);
if (spare_ != NULL) {
spare_ = block_start;
DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
(!blocks_.is_empty() && prev_limit != NULL));
// Interceptor functions called from generated inline caches to notify
// CPU profiler that external callbacks are invoked.
void InvokeAccessorGetterCallback(
v8::Local<v8::Name> property,
const v8::PropertyCallbackInfo<v8::Value>& info,
v8::AccessorNameGetterCallback getter);
void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
v8::FunctionCallback callback);
class Testing {
static v8::Testing::StressType stress_type() { return stress_type_; }
static void set_stress_type(v8::Testing::StressType stress_type) {
stress_type_ = stress_type;
static v8::Testing::StressType stress_type_;
} } // namespace v8::internal
#endif // V8_API_H_