src/api.h

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  27
  28 #ifndef V8_API_H_
  29 #define V8_API_H_
  30
  31 #include "v8.h"
  32
  33 #include "../include/v8-testing.h"
  34 #include "contexts.h"
  35 #include "factory.h"
  36 #include "isolate.h"
  37 #include "list-inl.h"
  38
  39 namespace v8 {
  40
  41 // Constants used in the implementation of the API.  The most natural thing
  42 // would usually be to place these with the classes that use them, but
  43 // we want to keep them out of v8.h because it is an externally
  44 // visible file.
  45 class Consts {
  46  public:
  47   enum TemplateType {
  48     FUNCTION_TEMPLATE = 0,
  49     OBJECT_TEMPLATE = 1
  50   };
  51 };
  52
  53
  54 // Utilities for working with neander-objects, primitive
  55 // env-independent JSObjects used by the api.
  56 class NeanderObject {
  57  public:
  58   explicit NeanderObject(v8::internal::Isolate* isolate, int size);
  59   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
  60   explicit inline NeanderObject(v8::internal::Object* obj);
  61   inline v8::internal::Object* get(int index);
  62   inline void set(int index, v8::internal::Object* value);
  63   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
  64   int size();
  65  private:
  66   v8::internal::Handle<v8::internal::JSObject> value_;
  67 };
  68
  69
  70 // Utilities for working with neander-arrays, a simple extensible
  71 // array abstraction built on neander-objects.
  72 class NeanderArray {
  73  public:
  74   explicit NeanderArray(v8::internal::Isolate* isolate);
  75   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
  76   inline v8::internal::Handle<v8::internal::JSObject> value() {
  77     return obj_.value();
  78   }
  79
  80   void add(v8::internal::Handle<v8::internal::Object> value);
  81
  82   int length();
  83
  84   v8::internal::Object* get(int index);
  85   // Change the value at an index to undefined value. If the index is
  86   // out of bounds, the request is ignored. Returns the old value.
  87   void set(int index, v8::internal::Object* value);
  88  private:
  89   NeanderObject obj_;
  90 };
  91
  92
  93 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
  94     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
  95
  96
  97 NeanderObject::NeanderObject(v8::internal::Object* obj)
  98     : value_(v8::internal::Handle<v8::internal::JSObject>(
  99         v8::internal::JSObject::cast(obj))) { }
 100
 101
 102 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
 103     : obj_(obj) { }
 104
 105
 106 v8::internal::Object* NeanderObject::get(int offset) {
 107   ASSERT(value()->HasFastObjectElements());
 108   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
 109 }
 110
 111
 112 void NeanderObject::set(int offset, v8::internal::Object* value) {
 113   ASSERT(value_->HasFastObjectElements());
 114   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
 115 }
 116
 117
 118 template <typename T> inline T ToCData(v8::internal::Object* obj) {
 119   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 120   return reinterpret_cast<T>(
 121       reinterpret_cast<intptr_t>(
 122           v8::internal::Foreign::cast(obj)->foreign_address()));
 123 }
 124
 125
 126 template <typename T>
 127 inline v8::internal::Handle<v8::internal::Object> FromCData(
 128     v8::internal::Isolate* isolate, T obj) {
 129   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 130   return isolate->factory()->NewForeign(
 131       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 132 }
 133
 134
 135 class ApiFunction {
 136  public:
 137   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 138   v8::internal::Address address() { return addr_; }
 139  private:
 140   v8::internal::Address addr_;
 141 };
 142
 143
 144
 145 class RegisteredExtension {
 146  public:
 147   explicit RegisteredExtension(Extension* extension);
 148   static void Register(RegisteredExtension* that);
 149   static void UnregisterAll();
 150   Extension* extension() { return extension_; }
 151   RegisteredExtension* next() { return next_; }
 152   static RegisteredExtension* first_extension() { return first_extension_; }
 153  private:
 154   Extension* extension_;
 155   RegisteredExtension* next_;
 156   static RegisteredExtension* first_extension_;
 157 };
 158
 159
 160 #define OPEN_HANDLE_LIST(V)                    \
 161   V(Template, TemplateInfo)                    \
 162   V(FunctionTemplate, FunctionTemplateInfo)    \
 163   V(ObjectTemplate, ObjectTemplateInfo)        \
 164   V(Signature, SignatureInfo)                  \
 165   V(AccessorSignature, FunctionTemplateInfo)   \
 166   V(TypeSwitch, TypeSwitchInfo)                \
 167   V(Data, Object)                              \
 168   V(RegExp, JSRegExp)                          \
 169   V(Object, JSObject)                          \
 170   V(Array, JSArray)                            \
 171   V(ArrayBuffer, JSArrayBuffer)                \
 172   V(ArrayBufferView, JSArrayBufferView)        \
 173   V(TypedArray, JSTypedArray)                  \
 174   V(Uint8Array, JSTypedArray)                  \
 175   V(Uint8ClampedArray, JSTypedArray)           \
 176   V(Int8Array, JSTypedArray)                   \
 177   V(Uint16Array, JSTypedArray)                 \
 178   V(Int16Array, JSTypedArray)                  \
 179   V(Uint32Array, JSTypedArray)                 \
 180   V(Int32Array, JSTypedArray)                  \
 181   V(Float32Array, JSTypedArray)                \
 182   V(Float64Array, JSTypedArray)                \
 183   V(DataView, JSDataView)                      \
 184   V(String, String)                            \
 185   V(Symbol, Symbol)                            \
 186   V(Script, JSFunction)                        \
 187   V(UnboundScript, SharedFunctionInfo)         \
 188   V(Function, JSFunction)                      \
 189   V(Message, JSObject)                         \
 190   V(Context, Context)                          \
 191   V(External, Foreign)                         \
 192   V(StackTrace, JSArray)                       \
 193   V(StackFrame, JSObject)                      \
 194   V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 195
 196
 197 class Utils {
 198  public:
 199   static inline bool ApiCheck(bool condition,
 200                               const char* location,
 201                               const char* message) {
 202     if (!condition) Utils::ReportApiFailure(location, message);
 203     return condition;
 204   }
 205
 206   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 207   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 208
 209   static inline Local<Context> ToLocal(
 210       v8::internal::Handle<v8::internal::Context> obj);
 211   static inline Local<Value> ToLocal(
 212       v8::internal::Handle<v8::internal::Object> obj);
 213   static inline Local<Function> ToLocal(
 214       v8::internal::Handle<v8::internal::JSFunction> obj);
 215   static inline Local<String> ToLocal(
 216       v8::internal::Handle<v8::internal::String> obj);
 217   static inline Local<Symbol> ToLocal(
 218       v8::internal::Handle<v8::internal::Symbol> obj);
 219   static inline Local<RegExp> ToLocal(
 220       v8::internal::Handle<v8::internal::JSRegExp> obj);
 221   static inline Local<Object> ToLocal(
 222       v8::internal::Handle<v8::internal::JSObject> obj);
 223   static inline Local<Array> ToLocal(
 224       v8::internal::Handle<v8::internal::JSArray> obj);
 225   static inline Local<ArrayBuffer> ToLocal(
 226       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 227   static inline Local<ArrayBufferView> ToLocal(
 228       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 229   static inline Local<DataView> ToLocal(
 230       v8::internal::Handle<v8::internal::JSDataView> obj);
 231
 232   static inline Local<TypedArray> ToLocal(
 233       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 234   static inline Local<Uint8Array> ToLocalUint8Array(
 235       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 236   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 237       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 238   static inline Local<Int8Array> ToLocalInt8Array(
 239       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 240   static inline Local<Uint16Array> ToLocalUint16Array(
 241       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 242   static inline Local<Int16Array> ToLocalInt16Array(
 243       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 244   static inline Local<Uint32Array> ToLocalUint32Array(
 245       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 246   static inline Local<Int32Array> ToLocalInt32Array(
 247       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 248   static inline Local<Float32Array> ToLocalFloat32Array(
 249       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 250   static inline Local<Float64Array> ToLocalFloat64Array(
 251       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 252
 253   static inline Local<Message> MessageToLocal(
 254       v8::internal::Handle<v8::internal::Object> obj);
 255   static inline Local<StackTrace> StackTraceToLocal(
 256       v8::internal::Handle<v8::internal::JSArray> obj);
 257   static inline Local<StackFrame> StackFrameToLocal(
 258       v8::internal::Handle<v8::internal::JSObject> obj);
 259   static inline Local<Number> NumberToLocal(
 260       v8::internal::Handle<v8::internal::Object> obj);
 261   static inline Local<Integer> IntegerToLocal(
 262       v8::internal::Handle<v8::internal::Object> obj);
 263   static inline Local<Uint32> Uint32ToLocal(
 264       v8::internal::Handle<v8::internal::Object> obj);
 265   static inline Local<FunctionTemplate> ToLocal(
 266       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 267   static inline Local<ObjectTemplate> ToLocal(
 268       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 269   static inline Local<Signature> ToLocal(
 270       v8::internal::Handle<v8::internal::SignatureInfo> obj);
 271   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 272       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 273   static inline Local<TypeSwitch> ToLocal(
 274       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 275   static inline Local<External> ExternalToLocal(
 276       v8::internal::Handle<v8::internal::JSObject> obj);
 277   static inline Local<DeclaredAccessorDescriptor> ToLocal(
 278       v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);
 279
 280 #define DECLARE_OPEN_HANDLE(From, To) \
 281   static inline v8::internal::Handle<v8::internal::To> \
 282       OpenHandle(const From* that, bool allow_empty_handle = false);
 283
 284 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 285
 286 #undef DECLARE_OPEN_HANDLE
 287
 288   template<class From, class To>
 289   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 290     ASSERT(obj.is_null() || !obj->IsTheHole());
 291     return Local<To>(reinterpret_cast<To*>(obj.location()));
 292   }
 293
 294   template <class T>
 295   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 296       const v8::Persistent<T>& persistent) {
 297     return v8::internal::Handle<v8::internal::Object>(
 298         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 299   }
 300
 301   template <class T>
 302   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 303       v8::Persistent<T>* persistent) {
 304     return OpenPersistent(*persistent);
 305   }
 306
 307   template <class From, class To>
 308   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 309     return OpenHandle(*handle);
 310   }
 311
 312  private:
 313   static void ReportApiFailure(const char* location, const char* message);
 314 };
 315
 316
 317 template <class T>
 318 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 319     v8::EscapableHandleScope* scope) {
 320   v8::internal::Handle<T> handle;
 321   if (!is_null()) {
 322     handle = *this;
 323   }
 324   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 325 }
 326
 327
 328 template <class T>
 329 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 330   return reinterpret_cast<T*>(obj.location());
 331 }
 332
 333 template <class T>
 334 inline v8::Local<T> ToApiHandle(
 335     v8::internal::Handle<v8::internal::Object> obj) {
 336   return Utils::Convert<v8::internal::Object, T>(obj);
 337 }
 338
 339
 340 // Implementations of ToLocal
 341
 342 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 343   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 344     return Convert<v8::internal::From, v8::To>(obj);  \
 345   }
 346
 347
 348 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)        \
 349   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                       \
 350       v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \
 351     ASSERT(obj->type() == kExternal##Type##Array);                          \
 352     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj);       \
 353   }
 354
 355
 356 MAKE_TO_LOCAL(ToLocal, Context, Context)
 357 MAKE_TO_LOCAL(ToLocal, Object, Value)
 358 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 359 MAKE_TO_LOCAL(ToLocal, String, String)
 360 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 361 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 362 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 363 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 364 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 365 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 366 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 367 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 368
 369 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 370
 371 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 372 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 373 MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
 374 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 375 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 376 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 377 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 378 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 379 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 380 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 381 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 382 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 383 MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 384
 385 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 386 #undef MAKE_TO_LOCAL
 387
 388
 389 // Implementations of OpenHandle
 390
 391 #define MAKE_OPEN_HANDLE(From, To)                                          \
 392   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \
 393     const v8::From* that, bool allow_empty_handle) {                        \
 394     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
 395     EXTRA_CHECK(that == NULL ||                                             \
 396         !(*reinterpret_cast<v8::internal::To**>(                            \
 397             const_cast<v8::From*>(that)))->IsFailure());                    \
 398     return v8::internal::Handle<v8::internal::To>(                          \
 399         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
 400   }
 401
 402 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 403
 404 #undef MAKE_OPEN_HANDLE
 405 #undef OPEN_HANDLE_LIST
 406
 407
 408 namespace internal {
 409
 410 // Tracks string usage to help make better decisions when
 411 // externalizing strings.
 412 //
 413 // Implementation note: internally this class only tracks fresh
 414 // strings and keeps a single use counter for them.
 415 class StringTracker {
 416  public:
 417   // Records that the given string's characters were copied to some
 418   // external buffer. If this happens often we should honor
 419   // externalization requests for the string.
 420   void RecordWrite(Handle<String> string) {
 421     Address address = reinterpret_cast<Address>(*string);
 422     Address top = isolate_->heap()->NewSpaceTop();
 423     if (IsFreshString(address, top)) {
 424       IncrementUseCount(top);
 425     }
 426   }
 427
 428   // Estimates freshness and use frequency of the given string based
 429   // on how close it is to the new space top and the recorded usage
 430   // history.
 431   inline bool IsFreshUnusedString(Handle<String> string) {
 432     Address address = reinterpret_cast<Address>(*string);
 433     Address top = isolate_->heap()->NewSpaceTop();
 434     return IsFreshString(address, top) && IsUseCountLow(top);
 435   }
 436
 437  private:
 438   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 439
 440   static inline bool IsFreshString(Address string, Address top) {
 441     return top - kFreshnessLimit <= string && string <= top;
 442   }
 443
 444   inline bool IsUseCountLow(Address top) {
 445     if (last_top_ != top) return true;
 446     return use_count_ < kUseLimit;
 447   }
 448
 449   inline void IncrementUseCount(Address top) {
 450     if (last_top_ != top) {
 451       use_count_ = 0;
 452       last_top_ = top;
 453     }
 454     ++use_count_;
 455   }
 456
 457   // Single use counter shared by all fresh strings.
 458   int use_count_;
 459
 460   // Last new space top when the use count above was valid.
 461   Address last_top_;
 462
 463   Isolate* isolate_;
 464
 465   // How close to the new space top a fresh string has to be.
 466   static const int kFreshnessLimit = 1024;
 467
 468   // The number of uses required to consider a string useful.
 469   static const int kUseLimit = 32;
 470
 471   friend class Isolate;
 472
 473   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 474 };
 475
 476
 477 class DeferredHandles {
 478  public:
 479   ~DeferredHandles();
 480
 481  private:
 482   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 483       : next_(NULL),
 484         previous_(NULL),
 485         first_block_limit_(first_block_limit),
 486         isolate_(isolate) {
 487     isolate->LinkDeferredHandles(this);
 488   }
 489
 490   void Iterate(ObjectVisitor* v);
 491
 492   List<Object**> blocks_;
 493   DeferredHandles* next_;
 494   DeferredHandles* previous_;
 495   Object** first_block_limit_;
 496   Isolate* isolate_;
 497
 498   friend class HandleScopeImplementer;
 499   friend class Isolate;
 500 };
 501
 502
 503 // This class is here in order to be able to declare it a friend of
 504 // HandleScope.  Moving these methods to be members of HandleScope would be
 505 // neat in some ways, but it would expose internal implementation details in
 506 // our public header file, which is undesirable.
 507 //
 508 // An isolate has a single instance of this class to hold the current thread's
 509 // data. In multithreaded V8 programs this data is copied in and out of storage
 510 // so that the currently executing thread always has its own copy of this
 511 // data.
 512 class HandleScopeImplementer {
 513  public:
 514   explicit HandleScopeImplementer(Isolate* isolate)
 515       : isolate_(isolate),
 516         blocks_(0),
 517         entered_contexts_(0),
 518         saved_contexts_(0),
 519         spare_(NULL),
 520         call_depth_(0),
 521         last_handle_before_deferred_block_(NULL) { }
 522
 523   ~HandleScopeImplementer() {
 524     DeleteArray(spare_);
 525   }
 526
 527   // Threading support for handle data.
 528   static int ArchiveSpacePerThread();
 529   char* RestoreThread(char* from);
 530   char* ArchiveThread(char* to);
 531   void FreeThreadResources();
 532
 533   // Garbage collection support.
 534   void Iterate(v8::internal::ObjectVisitor* v);
 535   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 536
 537
 538   inline internal::Object** GetSpareOrNewBlock();
 539   inline void DeleteExtensions(internal::Object** prev_limit);
 540
 541   inline void IncrementCallDepth() {call_depth_++;}
 542   inline void DecrementCallDepth() {call_depth_--;}
 543   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 544
 545   inline void EnterContext(Handle<Context> context);
 546   inline void LeaveContext();
 547   inline bool LastEnteredContextWas(Handle<Context> context);
 548
 549   // Returns the last entered context or an empty handle if no
 550   // contexts have been entered.
 551   inline Handle<Context> LastEnteredContext();
 552
 553   inline void SaveContext(Context* context);
 554   inline Context* RestoreContext();
 555   inline bool HasSavedContexts();
 556
 557   inline List<internal::Object**>* blocks() { return &blocks_; }
 558   Isolate* isolate() const { return isolate_; }
 559
 560   void ReturnBlock(Object** block) {
 561     ASSERT(block != NULL);
 562     if (spare_ != NULL) DeleteArray(spare_);
 563     spare_ = block;
 564   }
 565
 566  private:
 567   void ResetAfterArchive() {
 568     blocks_.Initialize(0);
 569     entered_contexts_.Initialize(0);
 570     saved_contexts_.Initialize(0);
 571     spare_ = NULL;
 572     last_handle_before_deferred_block_ = NULL;
 573     call_depth_ = 0;
 574   }
 575
 576   void Free() {
 577     ASSERT(blocks_.length() == 0);
 578     ASSERT(entered_contexts_.length() == 0);
 579     ASSERT(saved_contexts_.length() == 0);
 580     blocks_.Free();
 581     entered_contexts_.Free();
 582     saved_contexts_.Free();
 583     if (spare_ != NULL) {
 584       DeleteArray(spare_);
 585       spare_ = NULL;
 586     }
 587     ASSERT(call_depth_ == 0);
 588   }
 589
 590   void BeginDeferredScope();
 591   DeferredHandles* Detach(Object** prev_limit);
 592
 593   Isolate* isolate_;
 594   List<internal::Object**> blocks_;
 595   // Used as a stack to keep track of entered contexts.
 596   List<Context*> entered_contexts_;
 597   // Used as a stack to keep track of saved contexts.
 598   List<Context*> saved_contexts_;
 599   Object** spare_;
 600   int call_depth_;
 601   Object** last_handle_before_deferred_block_;
 602   // This is only used for threading support.
 603   HandleScopeData handle_scope_data_;
 604
 605   void IterateThis(ObjectVisitor* v);
 606   char* RestoreThreadHelper(char* from);
 607   char* ArchiveThreadHelper(char* to);
 608
 609   friend class DeferredHandles;
 610   friend class DeferredHandleScope;
 611
 612   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 613 };
 614
 615
 616 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 617
 618
 619 void HandleScopeImplementer::SaveContext(Context* context) {
 620   saved_contexts_.Add(context);
 621 }
 622
 623
 624 Context* HandleScopeImplementer::RestoreContext() {
 625   return saved_contexts_.RemoveLast();
 626 }
 627
 628
 629 bool HandleScopeImplementer::HasSavedContexts() {
 630   return !saved_contexts_.is_empty();
 631 }
 632
 633
 634 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 635   entered_contexts_.Add(*context);
 636 }
 637
 638
 639 void HandleScopeImplementer::LeaveContext() {
 640   entered_contexts_.RemoveLast();
 641 }
 642
 643
 644 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 645   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 646 }
 647
 648
 649 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 650   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 651   return Handle<Context>(entered_contexts_.last());
 652 }
 653
 654
 655 // If there's a spare block, use it for growing the current scope.
 656 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 657   internal::Object** block = (spare_ != NULL) ?
 658       spare_ :
 659       NewArray<internal::Object*>(kHandleBlockSize);
 660   spare_ = NULL;
 661   return block;
 662 }
 663
 664
 665 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 666   while (!blocks_.is_empty()) {
 667     internal::Object** block_start = blocks_.last();
 668     internal::Object** block_limit = block_start + kHandleBlockSize;
 669 #ifdef DEBUG
 670     // SealHandleScope may make the prev_limit to point inside the block.
 671     if (block_start <= prev_limit && prev_limit <= block_limit) {
 672 #ifdef ENABLE_HANDLE_ZAPPING
 673       internal::HandleScope::ZapRange(prev_limit, block_limit);
 674 #endif
 675       break;
 676     }
 677 #else
 678     if (prev_limit == block_limit) break;
 679 #endif
 680
 681     blocks_.RemoveLast();
 682 #ifdef ENABLE_HANDLE_ZAPPING
 683     internal::HandleScope::ZapRange(block_start, block_limit);
 684 #endif
 685     if (spare_ != NULL) {
 686       DeleteArray(spare_);
 687     }
 688     spare_ = block_start;
 689   }
 690   ASSERT((blocks_.is_empty() && prev_limit == NULL) ||
 691          (!blocks_.is_empty() && prev_limit != NULL));
 692 }
 693
 694
 695 // Interceptor functions called from generated inline caches to notify
 696 // CPU profiler that external callbacks are invoked.
 697 void InvokeAccessorGetterCallback(
 698     v8::Local<v8::String> property,
 699     const v8::PropertyCallbackInfo<v8::Value>& info,
 700     v8::AccessorGetterCallback getter);
 701
 702 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 703                             v8::FunctionCallback callback);
 704
 705 class Testing {
 706  public:
 707   static v8::Testing::StressType stress_type() { return stress_type_; }
 708   static void set_stress_type(v8::Testing::StressType stress_type) {
 709     stress_type_ = stress_type;
 710   }
 711
 712  private:
 713   static v8::Testing::StressType stress_type_;
 714 };
 715
 716 } }  // namespace v8::internal
 717
 718 #endif  // V8_API_H_