deps/v8/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, FunctionTemplateInfo)         \
 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(NativeWeakMap, JSWeakMap)
 174
 175 class Utils {
 176  public:
 177   static inline bool ApiCheck(bool condition,
 178                               const char* location,
 179                               const char* message) {
 180     if (!condition) Utils::ReportApiFailure(location, message);
 181     return condition;
 182   }
 183
 184   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 185   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 186
 187   static inline Local<Context> ToLocal(
 188       v8::internal::Handle<v8::internal::Context> obj);
 189   static inline Local<Value> ToLocal(
 190       v8::internal::Handle<v8::internal::Object> obj);
 191   static inline Local<Function> ToLocal(
 192       v8::internal::Handle<v8::internal::JSFunction> obj);
 193   static inline Local<Name> ToLocal(
 194       v8::internal::Handle<v8::internal::Name> obj);
 195   static inline Local<String> ToLocal(
 196       v8::internal::Handle<v8::internal::String> obj);
 197   static inline Local<Symbol> ToLocal(
 198       v8::internal::Handle<v8::internal::Symbol> obj);
 199   static inline Local<RegExp> ToLocal(
 200       v8::internal::Handle<v8::internal::JSRegExp> obj);
 201   static inline Local<Object> ToLocal(
 202       v8::internal::Handle<v8::internal::JSObject> obj);
 203   static inline Local<Array> ToLocal(
 204       v8::internal::Handle<v8::internal::JSArray> obj);
 205   static inline Local<ArrayBuffer> ToLocal(
 206       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 207   static inline Local<ArrayBufferView> ToLocal(
 208       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 209   static inline Local<DataView> ToLocal(
 210       v8::internal::Handle<v8::internal::JSDataView> obj);
 211
 212   static inline Local<TypedArray> ToLocal(
 213       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 214   static inline Local<Uint8Array> ToLocalUint8Array(
 215       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 216   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 217       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 218   static inline Local<Int8Array> ToLocalInt8Array(
 219       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 220   static inline Local<Uint16Array> ToLocalUint16Array(
 221       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 222   static inline Local<Int16Array> ToLocalInt16Array(
 223       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 224   static inline Local<Uint32Array> ToLocalUint32Array(
 225       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 226   static inline Local<Int32Array> ToLocalInt32Array(
 227       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 228   static inline Local<Float32Array> ToLocalFloat32Array(
 229       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 230   static inline Local<Float64Array> ToLocalFloat64Array(
 231       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 232
 233   static inline Local<Message> MessageToLocal(
 234       v8::internal::Handle<v8::internal::Object> obj);
 235   static inline Local<Promise> PromiseToLocal(
 236       v8::internal::Handle<v8::internal::JSObject> obj);
 237   static inline Local<StackTrace> StackTraceToLocal(
 238       v8::internal::Handle<v8::internal::JSArray> obj);
 239   static inline Local<StackFrame> StackFrameToLocal(
 240       v8::internal::Handle<v8::internal::JSObject> obj);
 241   static inline Local<Number> NumberToLocal(
 242       v8::internal::Handle<v8::internal::Object> obj);
 243   static inline Local<Integer> IntegerToLocal(
 244       v8::internal::Handle<v8::internal::Object> obj);
 245   static inline Local<Uint32> Uint32ToLocal(
 246       v8::internal::Handle<v8::internal::Object> obj);
 247   static inline Local<FunctionTemplate> ToLocal(
 248       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 249   static inline Local<ObjectTemplate> ToLocal(
 250       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 251   static inline Local<Signature> SignatureToLocal(
 252       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 253   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 254       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 255   static inline Local<TypeSwitch> ToLocal(
 256       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 257   static inline Local<External> ExternalToLocal(
 258       v8::internal::Handle<v8::internal::JSObject> obj);
 259   static inline Local<NativeWeakMap> NativeWeakMapToLocal(
 260       v8::internal::Handle<v8::internal::JSWeakMap> obj);
 261
 262 #define DECLARE_OPEN_HANDLE(From, To) \
 263   static inline v8::internal::Handle<v8::internal::To> \
 264       OpenHandle(const From* that, bool allow_empty_handle = false);
 265
 266 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 267
 268 #undef DECLARE_OPEN_HANDLE
 269
 270   template<class From, class To>
 271   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 272     DCHECK(obj.is_null() || !obj->IsTheHole());
 273     return Local<To>(reinterpret_cast<To*>(obj.location()));
 274   }
 275
 276   template <class T>
 277   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 278       const v8::Persistent<T>& persistent) {
 279     return v8::internal::Handle<v8::internal::Object>(
 280         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 281   }
 282
 283   template <class T>
 284   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 285       v8::Persistent<T>* persistent) {
 286     return OpenPersistent(*persistent);
 287   }
 288
 289   template <class From, class To>
 290   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 291     return OpenHandle(*handle);
 292   }
 293
 294  private:
 295   static void ReportApiFailure(const char* location, const char* message);
 296 };
 297
 298
 299 template <class T>
 300 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 301     v8::EscapableHandleScope* scope) {
 302   v8::internal::Handle<T> handle;
 303   if (!is_null()) {
 304     handle = *this;
 305   }
 306   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 307 }
 308
 309
 310 template <class T>
 311 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 312   return reinterpret_cast<T*>(obj.location());
 313 }
 314
 315 template <class T>
 316 inline v8::Local<T> ToApiHandle(
 317     v8::internal::Handle<v8::internal::Object> obj) {
 318   return Utils::Convert<v8::internal::Object, T>(obj);
 319 }
 320
 321
 322 // Implementations of ToLocal
 323
 324 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 325   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 326     return Convert<v8::internal::From, v8::To>(obj);  \
 327   }
 328
 329
 330 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)        \
 331   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                       \
 332       v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \
 333     DCHECK(obj->type() == kExternal##Type##Array);                          \
 334     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj);       \
 335   }
 336
 337
 338 MAKE_TO_LOCAL(ToLocal, Context, Context)
 339 MAKE_TO_LOCAL(ToLocal, Object, Value)
 340 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 341 MAKE_TO_LOCAL(ToLocal, Name, Name)
 342 MAKE_TO_LOCAL(ToLocal, String, String)
 343 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 344 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 345 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 346 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 347 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 348 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 349 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 350 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 351
 352 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 353
 354 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 355 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 356 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
 357 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 358 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 359 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 360 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 361 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 362 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 363 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 364 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 365 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 366 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 367 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
 368
 369 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 370 #undef MAKE_TO_LOCAL
 371
 372
 373 // Implementations of OpenHandle
 374
 375 #define MAKE_OPEN_HANDLE(From, To)                                             \
 376   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
 377       const v8::From* that, bool allow_empty_handle) {                         \
 378     DCHECK(allow_empty_handle || that != NULL);                                \
 379     DCHECK(that == NULL ||                                                     \
 380            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 381     return v8::internal::Handle<v8::internal::To>(                             \
 382         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
 383   }
 384
 385 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 386
 387 #undef MAKE_OPEN_HANDLE
 388 #undef OPEN_HANDLE_LIST
 389
 390
 391 namespace internal {
 392
 393 // Tracks string usage to help make better decisions when
 394 // externalizing strings.
 395 //
 396 // Implementation note: internally this class only tracks fresh
 397 // strings and keeps a single use counter for them.
 398 class StringTracker {
 399  public:
 400   // Records that the given string's characters were copied to some
 401   // external buffer. If this happens often we should honor
 402   // externalization requests for the string.
 403   void RecordWrite(Handle<String> string) {
 404     Address address = reinterpret_cast<Address>(*string);
 405     Address top = isolate_->heap()->NewSpaceTop();
 406     if (IsFreshString(address, top)) {
 407       IncrementUseCount(top);
 408     }
 409   }
 410
 411   // Estimates freshness and use frequency of the given string based
 412   // on how close it is to the new space top and the recorded usage
 413   // history.
 414   inline bool IsFreshUnusedString(Handle<String> string) {
 415     Address address = reinterpret_cast<Address>(*string);
 416     Address top = isolate_->heap()->NewSpaceTop();
 417     return IsFreshString(address, top) && IsUseCountLow(top);
 418   }
 419
 420  private:
 421   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 422
 423   static inline bool IsFreshString(Address string, Address top) {
 424     return top - kFreshnessLimit <= string && string <= top;
 425   }
 426
 427   inline bool IsUseCountLow(Address top) {
 428     if (last_top_ != top) return true;
 429     return use_count_ < kUseLimit;
 430   }
 431
 432   inline void IncrementUseCount(Address top) {
 433     if (last_top_ != top) {
 434       use_count_ = 0;
 435       last_top_ = top;
 436     }
 437     ++use_count_;
 438   }
 439
 440   // Single use counter shared by all fresh strings.
 441   int use_count_;
 442
 443   // Last new space top when the use count above was valid.
 444   Address last_top_;
 445
 446   Isolate* isolate_;
 447
 448   // How close to the new space top a fresh string has to be.
 449   static const int kFreshnessLimit = 1024;
 450
 451   // The number of uses required to consider a string useful.
 452   static const int kUseLimit = 32;
 453
 454   friend class Isolate;
 455
 456   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 457 };
 458
 459
 460 class DeferredHandles {
 461  public:
 462   ~DeferredHandles();
 463
 464  private:
 465   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 466       : next_(NULL),
 467         previous_(NULL),
 468         first_block_limit_(first_block_limit),
 469         isolate_(isolate) {
 470     isolate->LinkDeferredHandles(this);
 471   }
 472
 473   void Iterate(ObjectVisitor* v);
 474
 475   List<Object**> blocks_;
 476   DeferredHandles* next_;
 477   DeferredHandles* previous_;
 478   Object** first_block_limit_;
 479   Isolate* isolate_;
 480
 481   friend class HandleScopeImplementer;
 482   friend class Isolate;
 483 };
 484
 485
 486 // This class is here in order to be able to declare it a friend of
 487 // HandleScope.  Moving these methods to be members of HandleScope would be
 488 // neat in some ways, but it would expose internal implementation details in
 489 // our public header file, which is undesirable.
 490 //
 491 // An isolate has a single instance of this class to hold the current thread's
 492 // data. In multithreaded V8 programs this data is copied in and out of storage
 493 // so that the currently executing thread always has its own copy of this
 494 // data.
 495 class HandleScopeImplementer {
 496  public:
 497   explicit HandleScopeImplementer(Isolate* isolate)
 498       : isolate_(isolate),
 499         blocks_(0),
 500         entered_contexts_(0),
 501         saved_contexts_(0),
 502         spare_(NULL),
 503         call_depth_(0),
 504         last_handle_before_deferred_block_(NULL) { }
 505
 506   ~HandleScopeImplementer() {
 507     DeleteArray(spare_);
 508   }
 509
 510   // Threading support for handle data.
 511   static int ArchiveSpacePerThread();
 512   char* RestoreThread(char* from);
 513   char* ArchiveThread(char* to);
 514   void FreeThreadResources();
 515
 516   // Garbage collection support.
 517   void Iterate(v8::internal::ObjectVisitor* v);
 518   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 519
 520
 521   inline internal::Object** GetSpareOrNewBlock();
 522   inline void DeleteExtensions(internal::Object** prev_limit);
 523
 524   inline void IncrementCallDepth() {call_depth_++;}
 525   inline void DecrementCallDepth() {call_depth_--;}
 526   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 527
 528   inline void EnterContext(Handle<Context> context);
 529   inline void LeaveContext();
 530   inline bool LastEnteredContextWas(Handle<Context> context);
 531
 532   // Returns the last entered context or an empty handle if no
 533   // contexts have been entered.
 534   inline Handle<Context> LastEnteredContext();
 535
 536   inline void SaveContext(Context* context);
 537   inline Context* RestoreContext();
 538   inline bool HasSavedContexts();
 539
 540   inline List<internal::Object**>* blocks() { return &blocks_; }
 541   Isolate* isolate() const { return isolate_; }
 542
 543   void ReturnBlock(Object** block) {
 544     DCHECK(block != NULL);
 545     if (spare_ != NULL) DeleteArray(spare_);
 546     spare_ = block;
 547   }
 548
 549  private:
 550   void ResetAfterArchive() {
 551     blocks_.Initialize(0);
 552     entered_contexts_.Initialize(0);
 553     saved_contexts_.Initialize(0);
 554     spare_ = NULL;
 555     last_handle_before_deferred_block_ = NULL;
 556     call_depth_ = 0;
 557   }
 558
 559   void Free() {
 560     DCHECK(blocks_.length() == 0);
 561     DCHECK(entered_contexts_.length() == 0);
 562     DCHECK(saved_contexts_.length() == 0);
 563     blocks_.Free();
 564     entered_contexts_.Free();
 565     saved_contexts_.Free();
 566     if (spare_ != NULL) {
 567       DeleteArray(spare_);
 568       spare_ = NULL;
 569     }
 570     DCHECK(call_depth_ == 0);
 571   }
 572
 573   void BeginDeferredScope();
 574   DeferredHandles* Detach(Object** prev_limit);
 575
 576   Isolate* isolate_;
 577   List<internal::Object**> blocks_;
 578   // Used as a stack to keep track of entered contexts.
 579   List<Context*> entered_contexts_;
 580   // Used as a stack to keep track of saved contexts.
 581   List<Context*> saved_contexts_;
 582   Object** spare_;
 583   int call_depth_;
 584   Object** last_handle_before_deferred_block_;
 585   // This is only used for threading support.
 586   HandleScopeData handle_scope_data_;
 587
 588   void IterateThis(ObjectVisitor* v);
 589   char* RestoreThreadHelper(char* from);
 590   char* ArchiveThreadHelper(char* to);
 591
 592   friend class DeferredHandles;
 593   friend class DeferredHandleScope;
 594
 595   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 596 };
 597
 598
 599 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 600
 601
 602 void HandleScopeImplementer::SaveContext(Context* context) {
 603   saved_contexts_.Add(context);
 604 }
 605
 606
 607 Context* HandleScopeImplementer::RestoreContext() {
 608   return saved_contexts_.RemoveLast();
 609 }
 610
 611
 612 bool HandleScopeImplementer::HasSavedContexts() {
 613   return !saved_contexts_.is_empty();
 614 }
 615
 616
 617 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 618   entered_contexts_.Add(*context);
 619 }
 620
 621
 622 void HandleScopeImplementer::LeaveContext() {
 623   entered_contexts_.RemoveLast();
 624 }
 625
 626
 627 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 628   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 629 }
 630
 631
 632 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 633   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 634   return Handle<Context>(entered_contexts_.last());
 635 }
 636
 637
 638 // If there's a spare block, use it for growing the current scope.
 639 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 640   internal::Object** block = (spare_ != NULL) ?
 641       spare_ :
 642       NewArray<internal::Object*>(kHandleBlockSize);
 643   spare_ = NULL;
 644   return block;
 645 }
 646
 647
 648 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 649   while (!blocks_.is_empty()) {
 650     internal::Object** block_start = blocks_.last();
 651     internal::Object** block_limit = block_start + kHandleBlockSize;
 652
 653     // SealHandleScope may make the prev_limit to point inside the block.
 654     if (block_start <= prev_limit && prev_limit <= block_limit) {
 655 #ifdef ENABLE_HANDLE_ZAPPING
 656       internal::HandleScope::ZapRange(prev_limit, block_limit);
 657 #endif
 658       break;
 659     }
 660
 661     blocks_.RemoveLast();
 662 #ifdef ENABLE_HANDLE_ZAPPING
 663     internal::HandleScope::ZapRange(block_start, block_limit);
 664 #endif
 665     if (spare_ != NULL) {
 666       DeleteArray(spare_);
 667     }
 668     spare_ = block_start;
 669   }
 670   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 671          (!blocks_.is_empty() && prev_limit != NULL));
 672 }
 673
 674
 675 // Interceptor functions called from generated inline caches to notify
 676 // CPU profiler that external callbacks are invoked.
 677 void InvokeAccessorGetterCallback(
 678     v8::Local<v8::Name> property,
 679     const v8::PropertyCallbackInfo<v8::Value>& info,
 680     v8::AccessorNameGetterCallback getter);
 681
 682 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 683                             v8::FunctionCallback callback);
 684
 685 class Testing {
 686  public:
 687   static v8::Testing::StressType stress_type() { return stress_type_; }
 688   static void set_stress_type(v8::Testing::StressType stress_type) {
 689     stress_type_ = stress_type;
 690   }
 691
 692  private:
 693   static v8::Testing::StressType stress_type_;
 694 };
 695
 696 } }  // namespace v8::internal
 697
 698 #endif  // V8_API_H_