src/api.h

   1 // Copyright 2012 the V8 project authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef V8_API_H_
   6 #define V8_API_H_
   7
   8 #include "src/v8.h"
   9
  10 #include "include/v8-testing.h"
  11 #include "src/contexts.h"
  12 #include "src/factory.h"
  13 #include "src/isolate.h"
  14 #include "src/list-inl.h"
  15
  16 namespace v8 {
  17
  18 // Constants used in the implementation of the API.  The most natural thing
  19 // would usually be to place these with the classes that use them, but
  20 // we want to keep them out of v8.h because it is an externally
  21 // visible file.
  22 class Consts {
  23  public:
  24   enum TemplateType {
  25     FUNCTION_TEMPLATE = 0,
  26     OBJECT_TEMPLATE = 1
  27   };
  28 };
  29
  30
  31 // Utilities for working with neander-objects, primitive
  32 // env-independent JSObjects used by the api.
  33 class NeanderObject {
  34  public:
  35   explicit NeanderObject(v8::internal::Isolate* isolate, int size);
  36   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
  37   explicit inline NeanderObject(v8::internal::Object* obj);
  38   inline v8::internal::Object* get(int index);
  39   inline void set(int index, v8::internal::Object* value);
  40   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
  41   int size();
  42  private:
  43   v8::internal::Handle<v8::internal::JSObject> value_;
  44 };
  45
  46
  47 // Utilities for working with neander-arrays, a simple extensible
  48 // array abstraction built on neander-objects.
  49 class NeanderArray {
  50  public:
  51   explicit NeanderArray(v8::internal::Isolate* isolate);
  52   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
  53   inline v8::internal::Handle<v8::internal::JSObject> value() {
  54     return obj_.value();
  55   }
  56
  57   void add(internal::Isolate* isolate,
  58            v8::internal::Handle<v8::internal::Object> value);
  59
  60   int length();
  61
  62   v8::internal::Object* get(int index);
  63   // Change the value at an index to undefined value. If the index is
  64   // out of bounds, the request is ignored. Returns the old value.
  65   void set(int index, v8::internal::Object* value);
  66  private:
  67   NeanderObject obj_;
  68 };
  69
  70
  71 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
  72     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
  73
  74
  75 NeanderObject::NeanderObject(v8::internal::Object* obj)
  76     : value_(v8::internal::Handle<v8::internal::JSObject>(
  77         v8::internal::JSObject::cast(obj))) { }
  78
  79
  80 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
  81     : obj_(obj) { }
  82
  83
  84 v8::internal::Object* NeanderObject::get(int offset) {
  85   DCHECK(value()->HasFastObjectElements());
  86   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
  87 }
  88
  89
  90 void NeanderObject::set(int offset, v8::internal::Object* value) {
  91   DCHECK(value_->HasFastObjectElements());
  92   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
  93 }
  94
  95
  96 template <typename T> inline T ToCData(v8::internal::Object* obj) {
  97   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
  98   return reinterpret_cast<T>(
  99       reinterpret_cast<intptr_t>(
 100           v8::internal::Foreign::cast(obj)->foreign_address()));
 101 }
 102
 103
 104 template <typename T>
 105 inline v8::internal::Handle<v8::internal::Object> FromCData(
 106     v8::internal::Isolate* isolate, T obj) {
 107   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 108   return isolate->factory()->NewForeign(
 109       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 110 }
 111
 112
 113 class ApiFunction {
 114  public:
 115   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 116   v8::internal::Address address() { return addr_; }
 117  private:
 118   v8::internal::Address addr_;
 119 };
 120
 121
 122
 123 class RegisteredExtension {
 124  public:
 125   explicit RegisteredExtension(Extension* extension);
 126   static void Register(RegisteredExtension* that);
 127   static void UnregisterAll();
 128   Extension* extension() { return extension_; }
 129   RegisteredExtension* next() { return next_; }
 130   static RegisteredExtension* first_extension() { return first_extension_; }
 131  private:
 132   Extension* extension_;
 133   RegisteredExtension* next_;
 134   static RegisteredExtension* first_extension_;
 135 };
 136
 137
 138 #define OPEN_HANDLE_LIST(V)                    \
 139   V(Template, TemplateInfo)                    \
 140   V(FunctionTemplate, FunctionTemplateInfo)    \
 141   V(ObjectTemplate, ObjectTemplateInfo)        \
 142   V(Signature, SignatureInfo)                  \
 143   V(AccessorSignature, FunctionTemplateInfo)   \
 144   V(TypeSwitch, TypeSwitchInfo)                \
 145   V(Data, Object)                              \
 146   V(RegExp, JSRegExp)                          \
 147   V(Object, JSObject)                          \
 148   V(Array, JSArray)                            \
 149   V(ArrayBuffer, JSArrayBuffer)                \
 150   V(ArrayBufferView, JSArrayBufferView)        \
 151   V(TypedArray, JSTypedArray)                  \
 152   V(Uint8Array, JSTypedArray)                  \
 153   V(Uint8ClampedArray, JSTypedArray)           \
 154   V(Int8Array, JSTypedArray)                   \
 155   V(Uint16Array, JSTypedArray)                 \
 156   V(Int16Array, JSTypedArray)                  \
 157   V(Uint32Array, JSTypedArray)                 \
 158   V(Int32Array, JSTypedArray)                  \
 159   V(Float32Array, JSTypedArray)                \
 160   V(Float64Array, JSTypedArray)                \
 161   V(DataView, JSDataView)                      \
 162   V(Name, Name)                                \
 163   V(String, String)                            \
 164   V(Symbol, Symbol)                            \
 165   V(Script, JSFunction)                        \
 166   V(UnboundScript, SharedFunctionInfo)         \
 167   V(Function, JSFunction)                      \
 168   V(Message, JSMessageObject)                  \
 169   V(Context, Context)                          \
 170   V(External, Object)                          \
 171   V(StackTrace, JSArray)                       \
 172   V(StackFrame, JSObject)                      \
 173   V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 174
 175
 176 class Utils {
 177  public:
 178   static inline bool ApiCheck(bool condition,
 179                               const char* location,
 180                               const char* message) {
 181     if (!condition) Utils::ReportApiFailure(location, message);
 182     return condition;
 183   }
 184
 185   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 186   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 187
 188   static inline Local<Context> ToLocal(
 189       v8::internal::Handle<v8::internal::Context> obj);
 190   static inline Local<Value> ToLocal(
 191       v8::internal::Handle<v8::internal::Object> obj);
 192   static inline Local<Function> ToLocal(
 193       v8::internal::Handle<v8::internal::JSFunction> obj);
 194   static inline Local<Name> ToLocal(
 195       v8::internal::Handle<v8::internal::Name> obj);
 196   static inline Local<String> ToLocal(
 197       v8::internal::Handle<v8::internal::String> obj);
 198   static inline Local<Symbol> ToLocal(
 199       v8::internal::Handle<v8::internal::Symbol> obj);
 200   static inline Local<RegExp> ToLocal(
 201       v8::internal::Handle<v8::internal::JSRegExp> obj);
 202   static inline Local<Object> ToLocal(
 203       v8::internal::Handle<v8::internal::JSObject> obj);
 204   static inline Local<Array> ToLocal(
 205       v8::internal::Handle<v8::internal::JSArray> obj);
 206   static inline Local<ArrayBuffer> ToLocal(
 207       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 208   static inline Local<ArrayBufferView> ToLocal(
 209       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 210   static inline Local<DataView> ToLocal(
 211       v8::internal::Handle<v8::internal::JSDataView> obj);
 212
 213   static inline Local<TypedArray> ToLocal(
 214       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 215   static inline Local<Uint8Array> ToLocalUint8Array(
 216       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 217   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 218       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 219   static inline Local<Int8Array> ToLocalInt8Array(
 220       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 221   static inline Local<Uint16Array> ToLocalUint16Array(
 222       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 223   static inline Local<Int16Array> ToLocalInt16Array(
 224       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 225   static inline Local<Uint32Array> ToLocalUint32Array(
 226       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 227   static inline Local<Int32Array> ToLocalInt32Array(
 228       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 229   static inline Local<Float32Array> ToLocalFloat32Array(
 230       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 231   static inline Local<Float64Array> ToLocalFloat64Array(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233
 234   static inline Local<Message> MessageToLocal(
 235       v8::internal::Handle<v8::internal::Object> obj);
 236   static inline Local<Promise> PromiseToLocal(
 237       v8::internal::Handle<v8::internal::JSObject> obj);
 238   static inline Local<StackTrace> StackTraceToLocal(
 239       v8::internal::Handle<v8::internal::JSArray> obj);
 240   static inline Local<StackFrame> StackFrameToLocal(
 241       v8::internal::Handle<v8::internal::JSObject> obj);
 242   static inline Local<Number> NumberToLocal(
 243       v8::internal::Handle<v8::internal::Object> obj);
 244   static inline Local<Integer> IntegerToLocal(
 245       v8::internal::Handle<v8::internal::Object> obj);
 246   static inline Local<Uint32> Uint32ToLocal(
 247       v8::internal::Handle<v8::internal::Object> obj);
 248   static inline Local<FunctionTemplate> ToLocal(
 249       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 250   static inline Local<ObjectTemplate> ToLocal(
 251       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 252   static inline Local<Signature> ToLocal(
 253       v8::internal::Handle<v8::internal::SignatureInfo> obj);
 254   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 255       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 256   static inline Local<TypeSwitch> ToLocal(
 257       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 258   static inline Local<External> ExternalToLocal(
 259       v8::internal::Handle<v8::internal::JSObject> obj);
 260   static inline Local<DeclaredAccessorDescriptor> ToLocal(
 261       v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);
 262
 263 #define DECLARE_OPEN_HANDLE(From, To) \
 264   static inline v8::internal::Handle<v8::internal::To> \
 265       OpenHandle(const From* that, bool allow_empty_handle = false);
 266
 267 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 268
 269 #undef DECLARE_OPEN_HANDLE
 270
 271   template<class From, class To>
 272   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 273     DCHECK(obj.is_null() || !obj->IsTheHole());
 274     return Local<To>(reinterpret_cast<To*>(obj.location()));
 275   }
 276
 277   template <class T>
 278   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 279       const v8::Persistent<T>& persistent) {
 280     return v8::internal::Handle<v8::internal::Object>(
 281         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 282   }
 283
 284   template <class T>
 285   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 286       v8::Persistent<T>* persistent) {
 287     return OpenPersistent(*persistent);
 288   }
 289
 290   template <class From, class To>
 291   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 292     return OpenHandle(*handle);
 293   }
 294
 295  private:
 296   static void ReportApiFailure(const char* location, const char* message);
 297 };
 298
 299
 300 template <class T>
 301 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 302     v8::EscapableHandleScope* scope) {
 303   v8::internal::Handle<T> handle;
 304   if (!is_null()) {
 305     handle = *this;
 306   }
 307   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 308 }
 309
 310
 311 template <class T>
 312 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 313   return reinterpret_cast<T*>(obj.location());
 314 }
 315
 316 template <class T>
 317 inline v8::Local<T> ToApiHandle(
 318     v8::internal::Handle<v8::internal::Object> obj) {
 319   return Utils::Convert<v8::internal::Object, T>(obj);
 320 }
 321
 322
 323 // Implementations of ToLocal
 324
 325 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 326   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 327     return Convert<v8::internal::From, v8::To>(obj);  \
 328   }
 329
 330
 331 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)        \
 332   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                       \
 333       v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \
 334     DCHECK(obj->type() == kExternal##Type##Array);                          \
 335     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj);       \
 336   }
 337
 338
 339 MAKE_TO_LOCAL(ToLocal, Context, Context)
 340 MAKE_TO_LOCAL(ToLocal, Object, Value)
 341 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 342 MAKE_TO_LOCAL(ToLocal, Name, Name)
 343 MAKE_TO_LOCAL(ToLocal, String, String)
 344 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 345 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 346 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 347 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 348 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 349 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 350 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 351 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 352
 353 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 354
 355 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 356 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 357 MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
 358 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 359 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 360 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 361 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 362 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 363 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 364 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 365 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 366 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 367 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 368 MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 369
 370 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 371 #undef MAKE_TO_LOCAL
 372
 373
 374 // Implementations of OpenHandle
 375
 376 #define MAKE_OPEN_HANDLE(From, To)                                          \
 377   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \
 378     const v8::From* that, bool allow_empty_handle) {                        \
 379     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
 380     EXTRA_CHECK(that == NULL ||                                             \
 381         (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 382     return v8::internal::Handle<v8::internal::To>(                          \
 383         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
 384   }
 385
 386 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 387
 388 #undef MAKE_OPEN_HANDLE
 389 #undef OPEN_HANDLE_LIST
 390
 391
 392 namespace internal {
 393
 394 // Tracks string usage to help make better decisions when
 395 // externalizing strings.
 396 //
 397 // Implementation note: internally this class only tracks fresh
 398 // strings and keeps a single use counter for them.
 399 class StringTracker {
 400  public:
 401   // Records that the given string's characters were copied to some
 402   // external buffer. If this happens often we should honor
 403   // externalization requests for the string.
 404   void RecordWrite(Handle<String> string) {
 405     Address address = reinterpret_cast<Address>(*string);
 406     Address top = isolate_->heap()->NewSpaceTop();
 407     if (IsFreshString(address, top)) {
 408       IncrementUseCount(top);
 409     }
 410   }
 411
 412   // Estimates freshness and use frequency of the given string based
 413   // on how close it is to the new space top and the recorded usage
 414   // history.
 415   inline bool IsFreshUnusedString(Handle<String> string) {
 416     Address address = reinterpret_cast<Address>(*string);
 417     Address top = isolate_->heap()->NewSpaceTop();
 418     return IsFreshString(address, top) && IsUseCountLow(top);
 419   }
 420
 421  private:
 422   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 423
 424   static inline bool IsFreshString(Address string, Address top) {
 425     return top - kFreshnessLimit <= string && string <= top;
 426   }
 427
 428   inline bool IsUseCountLow(Address top) {
 429     if (last_top_ != top) return true;
 430     return use_count_ < kUseLimit;
 431   }
 432
 433   inline void IncrementUseCount(Address top) {
 434     if (last_top_ != top) {
 435       use_count_ = 0;
 436       last_top_ = top;
 437     }
 438     ++use_count_;
 439   }
 440
 441   // Single use counter shared by all fresh strings.
 442   int use_count_;
 443
 444   // Last new space top when the use count above was valid.
 445   Address last_top_;
 446
 447   Isolate* isolate_;
 448
 449   // How close to the new space top a fresh string has to be.
 450   static const int kFreshnessLimit = 1024;
 451
 452   // The number of uses required to consider a string useful.
 453   static const int kUseLimit = 32;
 454
 455   friend class Isolate;
 456
 457   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 458 };
 459
 460
 461 class DeferredHandles {
 462  public:
 463   ~DeferredHandles();
 464
 465  private:
 466   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 467       : next_(NULL),
 468         previous_(NULL),
 469         first_block_limit_(first_block_limit),
 470         isolate_(isolate) {
 471     isolate->LinkDeferredHandles(this);
 472   }
 473
 474   void Iterate(ObjectVisitor* v);
 475
 476   List<Object**> blocks_;
 477   DeferredHandles* next_;
 478   DeferredHandles* previous_;
 479   Object** first_block_limit_;
 480   Isolate* isolate_;
 481
 482   friend class HandleScopeImplementer;
 483   friend class Isolate;
 484 };
 485
 486
 487 // This class is here in order to be able to declare it a friend of
 488 // HandleScope.  Moving these methods to be members of HandleScope would be
 489 // neat in some ways, but it would expose internal implementation details in
 490 // our public header file, which is undesirable.
 491 //
 492 // An isolate has a single instance of this class to hold the current thread's
 493 // data. In multithreaded V8 programs this data is copied in and out of storage
 494 // so that the currently executing thread always has its own copy of this
 495 // data.
 496 class HandleScopeImplementer {
 497  public:
 498   explicit HandleScopeImplementer(Isolate* isolate)
 499       : isolate_(isolate),
 500         blocks_(0),
 501         entered_contexts_(0),
 502         saved_contexts_(0),
 503         spare_(NULL),
 504         call_depth_(0),
 505         last_handle_before_deferred_block_(NULL) { }
 506
 507   ~HandleScopeImplementer() {
 508     DeleteArray(spare_);
 509   }
 510
 511   // Threading support for handle data.
 512   static int ArchiveSpacePerThread();
 513   char* RestoreThread(char* from);
 514   char* ArchiveThread(char* to);
 515   void FreeThreadResources();
 516
 517   // Garbage collection support.
 518   void Iterate(v8::internal::ObjectVisitor* v);
 519   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 520
 521
 522   inline internal::Object** GetSpareOrNewBlock();
 523   inline void DeleteExtensions(internal::Object** prev_limit);
 524
 525   inline void IncrementCallDepth() {call_depth_++;}
 526   inline void DecrementCallDepth() {call_depth_--;}
 527   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 528
 529   inline void EnterContext(Handle<Context> context);
 530   inline void LeaveContext();
 531   inline bool LastEnteredContextWas(Handle<Context> context);
 532
 533   // Returns the last entered context or an empty handle if no
 534   // contexts have been entered.
 535   inline Handle<Context> LastEnteredContext();
 536
 537   inline void SaveContext(Context* context);
 538   inline Context* RestoreContext();
 539   inline bool HasSavedContexts();
 540
 541   inline List<internal::Object**>* blocks() { return &blocks_; }
 542   Isolate* isolate() const { return isolate_; }
 543
 544   void ReturnBlock(Object** block) {
 545     DCHECK(block != NULL);
 546     if (spare_ != NULL) DeleteArray(spare_);
 547     spare_ = block;
 548   }
 549
 550  private:
 551   void ResetAfterArchive() {
 552     blocks_.Initialize(0);
 553     entered_contexts_.Initialize(0);
 554     saved_contexts_.Initialize(0);
 555     spare_ = NULL;
 556     last_handle_before_deferred_block_ = NULL;
 557     call_depth_ = 0;
 558   }
 559
 560   void Free() {
 561     DCHECK(blocks_.length() == 0);
 562     DCHECK(entered_contexts_.length() == 0);
 563     DCHECK(saved_contexts_.length() == 0);
 564     blocks_.Free();
 565     entered_contexts_.Free();
 566     saved_contexts_.Free();
 567     if (spare_ != NULL) {
 568       DeleteArray(spare_);
 569       spare_ = NULL;
 570     }
 571     DCHECK(call_depth_ == 0);
 572   }
 573
 574   void BeginDeferredScope();
 575   DeferredHandles* Detach(Object** prev_limit);
 576
 577   Isolate* isolate_;
 578   List<internal::Object**> blocks_;
 579   // Used as a stack to keep track of entered contexts.
 580   List<Context*> entered_contexts_;
 581   // Used as a stack to keep track of saved contexts.
 582   List<Context*> saved_contexts_;
 583   Object** spare_;
 584   int call_depth_;
 585   Object** last_handle_before_deferred_block_;
 586   // This is only used for threading support.
 587   HandleScopeData handle_scope_data_;
 588
 589   void IterateThis(ObjectVisitor* v);
 590   char* RestoreThreadHelper(char* from);
 591   char* ArchiveThreadHelper(char* to);
 592
 593   friend class DeferredHandles;
 594   friend class DeferredHandleScope;
 595
 596   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 597 };
 598
 599
 600 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 601
 602
 603 void HandleScopeImplementer::SaveContext(Context* context) {
 604   saved_contexts_.Add(context);
 605 }
 606
 607
 608 Context* HandleScopeImplementer::RestoreContext() {
 609   return saved_contexts_.RemoveLast();
 610 }
 611
 612
 613 bool HandleScopeImplementer::HasSavedContexts() {
 614   return !saved_contexts_.is_empty();
 615 }
 616
 617
 618 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 619   entered_contexts_.Add(*context);
 620 }
 621
 622
 623 void HandleScopeImplementer::LeaveContext() {
 624   entered_contexts_.RemoveLast();
 625 }
 626
 627
 628 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 629   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 630 }
 631
 632
 633 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 634   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 635   return Handle<Context>(entered_contexts_.last());
 636 }
 637
 638
 639 // If there's a spare block, use it for growing the current scope.
 640 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 641   internal::Object** block = (spare_ != NULL) ?
 642       spare_ :
 643       NewArray<internal::Object*>(kHandleBlockSize);
 644   spare_ = NULL;
 645   return block;
 646 }
 647
 648
 649 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 650   while (!blocks_.is_empty()) {
 651     internal::Object** block_start = blocks_.last();
 652     internal::Object** block_limit = block_start + kHandleBlockSize;
 653 #ifdef DEBUG
 654     // SealHandleScope may make the prev_limit to point inside the block.
 655     if (block_start <= prev_limit && prev_limit <= block_limit) {
 656 #ifdef ENABLE_HANDLE_ZAPPING
 657       internal::HandleScope::ZapRange(prev_limit, block_limit);
 658 #endif
 659       break;
 660     }
 661 #else
 662     if (prev_limit == block_limit) break;
 663 #endif
 664
 665     blocks_.RemoveLast();
 666 #ifdef ENABLE_HANDLE_ZAPPING
 667     internal::HandleScope::ZapRange(block_start, block_limit);
 668 #endif
 669     if (spare_ != NULL) {
 670       DeleteArray(spare_);
 671     }
 672     spare_ = block_start;
 673   }
 674   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 675          (!blocks_.is_empty() && prev_limit != NULL));
 676 }
 677
 678
 679 // Interceptor functions called from generated inline caches to notify
 680 // CPU profiler that external callbacks are invoked.
 681 void InvokeAccessorGetterCallback(
 682     v8::Local<v8::Name> property,
 683     const v8::PropertyCallbackInfo<v8::Value>& info,
 684     v8::AccessorNameGetterCallback getter);
 685
 686 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 687                             v8::FunctionCallback callback);
 688
 689 class Testing {
 690  public:
 691   static v8::Testing::StressType stress_type() { return stress_type_; }
 692   static void set_stress_type(v8::Testing::StressType stress_type) {
 693     stress_type_ = stress_type;
 694   }
 695
 696  private:
 697   static v8::Testing::StressType stress_type_;
 698 };
 699
 700 } }  // namespace v8::internal
 701
 702 #endif  // V8_API_H_