src/api.h

   1 // Copyright 2012 the V8 project authors. All rights reserved.
   2 // Redistribution and use in source and binary forms, with or without
   3 // modification, are permitted provided that the following conditions are
   4 // met:
   5 //
   6 //     * Redistributions of source code must retain the above copyright
   7 //       notice, this list of conditions and the following disclaimer.
   8 //     * Redistributions in binary form must reproduce the above
   9 //       copyright notice, this list of conditions and the following
  10 //       disclaimer in the documentation and/or other materials provided
  11 //       with the distribution.
  12 //     * Neither the name of Google Inc. nor the names of its
  13 //       contributors may be used to endorse or promote products derived
  14 //       from this software without specific prior written permission.
  15 //
  16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  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 "apiutils.h"
  35 #include "contexts.h"
  36 #include "factory.h"
  37 #include "isolate.h"
  38 #include "list-inl.h"
  39
  40 namespace v8 {
  41
  42 // Constants used in the implementation of the API.  The most natural thing
  43 // would usually be to place these with the classes that use them, but
  44 // we want to keep them out of v8.h because it is an externally
  45 // visible file.
  46 class Consts {
  47  public:
  48   enum TemplateType {
  49     FUNCTION_TEMPLATE = 0,
  50     OBJECT_TEMPLATE = 1
  51   };
  52 };
  53
  54
  55 // Utilities for working with neander-objects, primitive
  56 // env-independent JSObjects used by the api.
  57 class NeanderObject {
  58  public:
  59   explicit NeanderObject(int size);
  60   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
  61   explicit inline NeanderObject(v8::internal::Object* obj);
  62   inline v8::internal::Object* get(int index);
  63   inline void set(int index, v8::internal::Object* value);
  64   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
  65   int size();
  66  private:
  67   v8::internal::Handle<v8::internal::JSObject> value_;
  68 };
  69
  70
  71 // Utilities for working with neander-arrays, a simple extensible
  72 // array abstraction built on neander-objects.
  73 class NeanderArray {
  74  public:
  75   NeanderArray();
  76   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
  77   inline v8::internal::Handle<v8::internal::JSObject> value() {
  78     return obj_.value();
  79   }
  80
  81   void add(v8::internal::Handle<v8::internal::Object> value);
  82
  83   int length();
  84
  85   v8::internal::Object* get(int index);
  86   // Change the value at an index to undefined value. If the index is
  87   // out of bounds, the request is ignored. Returns the old value.
  88   void set(int index, v8::internal::Object* value);
  89  private:
  90   NeanderObject obj_;
  91 };
  92
  93
  94 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
  95     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
  96
  97
  98 NeanderObject::NeanderObject(v8::internal::Object* obj)
  99     : value_(v8::internal::Handle<v8::internal::JSObject>(
 100         v8::internal::JSObject::cast(obj))) { }
 101
 102
 103 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
 104     : obj_(obj) { }
 105
 106
 107 v8::internal::Object* NeanderObject::get(int offset) {
 108   ASSERT(value()->HasFastObjectElements());
 109   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
 110 }
 111
 112
 113 void NeanderObject::set(int offset, v8::internal::Object* value) {
 114   ASSERT(value_->HasFastObjectElements());
 115   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
 116 }
 117
 118
 119 template <typename T> inline T ToCData(v8::internal::Object* obj) {
 120   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 121   return reinterpret_cast<T>(
 122       reinterpret_cast<intptr_t>(
 123           v8::internal::Foreign::cast(obj)->foreign_address()));
 124 }
 125
 126
 127 template <typename T>
 128 inline v8::internal::Handle<v8::internal::Object> FromCData(T obj) {
 129   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 130   return 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   RegisteredExtension* next_auto() { return next_auto_; }
 153   static RegisteredExtension* first_extension() { return first_extension_; }
 154  private:
 155   Extension* extension_;
 156   RegisteredExtension* next_;
 157   RegisteredExtension* next_auto_;
 158   static RegisteredExtension* first_extension_;
 159 };
 160
 161
 162 class Utils {
 163  public:
 164   static bool ReportApiFailure(const char* location, const char* message);
 165
 166   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 167   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 168
 169   static inline Local<Context> ToLocal(
 170       v8::internal::Handle<v8::internal::Context> obj);
 171   static inline Local<Value> ToLocal(
 172       v8::internal::Handle<v8::internal::Object> obj);
 173   static inline Local<Function> ToLocal(
 174       v8::internal::Handle<v8::internal::JSFunction> obj);
 175   static inline Local<String> ToLocal(
 176       v8::internal::Handle<v8::internal::String> obj);
 177   static inline Local<RegExp> ToLocal(
 178       v8::internal::Handle<v8::internal::JSRegExp> obj);
 179   static inline Local<Object> ToLocal(
 180       v8::internal::Handle<v8::internal::JSObject> obj);
 181   static inline Local<Array> ToLocal(
 182       v8::internal::Handle<v8::internal::JSArray> obj);
 183   static inline Local<External> ToLocal(
 184       v8::internal::Handle<v8::internal::Foreign> obj);
 185   static inline Local<Message> MessageToLocal(
 186       v8::internal::Handle<v8::internal::Object> obj);
 187   static inline Local<StackTrace> StackTraceToLocal(
 188       v8::internal::Handle<v8::internal::JSArray> obj);
 189   static inline Local<StackFrame> StackFrameToLocal(
 190       v8::internal::Handle<v8::internal::JSObject> obj);
 191   static inline Local<Number> NumberToLocal(
 192       v8::internal::Handle<v8::internal::Object> obj);
 193   static inline Local<Integer> IntegerToLocal(
 194       v8::internal::Handle<v8::internal::Object> obj);
 195   static inline Local<Uint32> Uint32ToLocal(
 196       v8::internal::Handle<v8::internal::Object> obj);
 197   static inline Local<FunctionTemplate> ToLocal(
 198       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 199   static inline Local<ObjectTemplate> ToLocal(
 200       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 201   static inline Local<Signature> ToLocal(
 202       v8::internal::Handle<v8::internal::SignatureInfo> obj);
 203   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 204       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 205   static inline Local<TypeSwitch> ToLocal(
 206       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 207
 208   static inline v8::internal::Handle<v8::internal::TemplateInfo>
 209       OpenHandle(const Template* that);
 210   static inline v8::internal::Handle<v8::internal::FunctionTemplateInfo>
 211       OpenHandle(const FunctionTemplate* that);
 212   static inline v8::internal::Handle<v8::internal::ObjectTemplateInfo>
 213       OpenHandle(const ObjectTemplate* that);
 214   static inline v8::internal::Handle<v8::internal::Object>
 215       OpenHandle(const Data* data);
 216   static inline v8::internal::Handle<v8::internal::JSRegExp>
 217       OpenHandle(const RegExp* data);
 218   static inline v8::internal::Handle<v8::internal::JSObject>
 219       OpenHandle(const v8::Object* data);
 220   static inline v8::internal::Handle<v8::internal::JSArray>
 221       OpenHandle(const v8::Array* data);
 222   static inline v8::internal::Handle<v8::internal::String>
 223       OpenHandle(const String* data);
 224   static inline v8::internal::Handle<v8::internal::Object>
 225       OpenHandle(const Script* data);
 226   static inline v8::internal::Handle<v8::internal::JSFunction>
 227       OpenHandle(const Function* data);
 228   static inline v8::internal::Handle<v8::internal::JSObject>
 229       OpenHandle(const Message* message);
 230   static inline v8::internal::Handle<v8::internal::JSArray>
 231       OpenHandle(const StackTrace* stack_trace);
 232   static inline v8::internal::Handle<v8::internal::JSObject>
 233       OpenHandle(const StackFrame* stack_frame);
 234   static inline v8::internal::Handle<v8::internal::Context>
 235       OpenHandle(const v8::Context* context);
 236   static inline v8::internal::Handle<v8::internal::SignatureInfo>
 237       OpenHandle(const v8::Signature* sig);
 238   static inline v8::internal::Handle<v8::internal::FunctionTemplateInfo>
 239       OpenHandle(const v8::AccessorSignature* sig);
 240   static inline v8::internal::Handle<v8::internal::TypeSwitchInfo>
 241       OpenHandle(const v8::TypeSwitch* that);
 242   static inline v8::internal::Handle<v8::internal::Foreign>
 243       OpenHandle(const v8::External* that);
 244 };
 245
 246
 247 template <class T>
 248 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 249   return reinterpret_cast<T*>(obj.location());
 250 }
 251
 252
 253 template <class T>
 254 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 255     v8::HandleScope* scope) {
 256   v8::internal::Handle<T> handle;
 257   if (!is_null()) {
 258     handle = *this;
 259   }
 260   return Utils::OpenHandle(*scope->Close(Utils::ToLocal(handle)));
 261 }
 262
 263
 264 // Implementations of ToLocal
 265
 266 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 267   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 268     ASSERT(obj.is_null() || !obj->IsTheHole());                             \
 269     return Local<To>(reinterpret_cast<To*>(obj.location()));                \
 270   }
 271
 272 MAKE_TO_LOCAL(ToLocal, Context, Context)
 273 MAKE_TO_LOCAL(ToLocal, Object, Value)
 274 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 275 MAKE_TO_LOCAL(ToLocal, String, String)
 276 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 277 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 278 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 279 MAKE_TO_LOCAL(ToLocal, Foreign, External)
 280 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 281 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 282 MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
 283 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 284 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 285 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 286 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 287 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 288 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 289 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 290 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 291
 292 #undef MAKE_TO_LOCAL
 293
 294
 295 // Implementations of OpenHandle
 296
 297 #define MAKE_OPEN_HANDLE(From, To) \
 298   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(\
 299     const v8::From* that) { \
 300     return v8::internal::Handle<v8::internal::To>( \
 301         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
 302   }
 303
 304 MAKE_OPEN_HANDLE(Template, TemplateInfo)
 305 MAKE_OPEN_HANDLE(FunctionTemplate, FunctionTemplateInfo)
 306 MAKE_OPEN_HANDLE(ObjectTemplate, ObjectTemplateInfo)
 307 MAKE_OPEN_HANDLE(Signature, SignatureInfo)
 308 MAKE_OPEN_HANDLE(AccessorSignature, FunctionTemplateInfo)
 309 MAKE_OPEN_HANDLE(TypeSwitch, TypeSwitchInfo)
 310 MAKE_OPEN_HANDLE(Data, Object)
 311 MAKE_OPEN_HANDLE(RegExp, JSRegExp)
 312 MAKE_OPEN_HANDLE(Object, JSObject)
 313 MAKE_OPEN_HANDLE(Array, JSArray)
 314 MAKE_OPEN_HANDLE(String, String)
 315 MAKE_OPEN_HANDLE(Script, Object)
 316 MAKE_OPEN_HANDLE(Function, JSFunction)
 317 MAKE_OPEN_HANDLE(Message, JSObject)
 318 MAKE_OPEN_HANDLE(Context, Context)
 319 MAKE_OPEN_HANDLE(External, Foreign)
 320 MAKE_OPEN_HANDLE(StackTrace, JSArray)
 321 MAKE_OPEN_HANDLE(StackFrame, JSObject)
 322
 323 #undef MAKE_OPEN_HANDLE
 324
 325
 326 namespace internal {
 327
 328 // Tracks string usage to help make better decisions when
 329 // externalizing strings.
 330 //
 331 // Implementation note: internally this class only tracks fresh
 332 // strings and keeps a single use counter for them.
 333 class StringTracker {
 334  public:
 335   // Records that the given string's characters were copied to some
 336   // external buffer. If this happens often we should honor
 337   // externalization requests for the string.
 338   void RecordWrite(Handle<String> string) {
 339     Address address = reinterpret_cast<Address>(*string);
 340     Address top = isolate_->heap()->NewSpaceTop();
 341     if (IsFreshString(address, top)) {
 342       IncrementUseCount(top);
 343     }
 344   }
 345
 346   // Estimates freshness and use frequency of the given string based
 347   // on how close it is to the new space top and the recorded usage
 348   // history.
 349   inline bool IsFreshUnusedString(Handle<String> string) {
 350     Address address = reinterpret_cast<Address>(*string);
 351     Address top = isolate_->heap()->NewSpaceTop();
 352     return IsFreshString(address, top) && IsUseCountLow(top);
 353   }
 354
 355  private:
 356   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 357
 358   static inline bool IsFreshString(Address string, Address top) {
 359     return top - kFreshnessLimit <= string && string <= top;
 360   }
 361
 362   inline bool IsUseCountLow(Address top) {
 363     if (last_top_ != top) return true;
 364     return use_count_ < kUseLimit;
 365   }
 366
 367   inline void IncrementUseCount(Address top) {
 368     if (last_top_ != top) {
 369       use_count_ = 0;
 370       last_top_ = top;
 371     }
 372     ++use_count_;
 373   }
 374
 375   // Single use counter shared by all fresh strings.
 376   int use_count_;
 377
 378   // Last new space top when the use count above was valid.
 379   Address last_top_;
 380
 381   Isolate* isolate_;
 382
 383   // How close to the new space top a fresh string has to be.
 384   static const int kFreshnessLimit = 1024;
 385
 386   // The number of uses required to consider a string useful.
 387   static const int kUseLimit = 32;
 388
 389   friend class Isolate;
 390
 391   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 392 };
 393
 394
 395 class DeferredHandles {
 396  public:
 397   ~DeferredHandles();
 398
 399  private:
 400   DeferredHandles(DeferredHandles* next, Object** first_block_limit,
 401                   HandleScopeImplementer* impl)
 402       : next_(next), previous_(NULL), first_block_limit_(first_block_limit),
 403         impl_(impl) {}
 404
 405   void Iterate(ObjectVisitor* v);
 406
 407   List<Object**> blocks_;
 408   DeferredHandles* next_;
 409   DeferredHandles* previous_;
 410   Object** first_block_limit_;
 411   HandleScopeImplementer* impl_;
 412
 413   friend class HandleScopeImplementer;
 414 };
 415
 416
 417 // This class is here in order to be able to declare it a friend of
 418 // HandleScope.  Moving these methods to be members of HandleScope would be
 419 // neat in some ways, but it would expose internal implementation details in
 420 // our public header file, which is undesirable.
 421 //
 422 // An isolate has a single instance of this class to hold the current thread's
 423 // data. In multithreaded V8 programs this data is copied in and out of storage
 424 // so that the currently executing thread always has its own copy of this
 425 // data.
 426 class HandleScopeImplementer {
 427  public:
 428   explicit HandleScopeImplementer(Isolate* isolate)
 429       : isolate_(isolate),
 430         blocks_(0),
 431         entered_contexts_(0),
 432         saved_contexts_(0),
 433         spare_(NULL),
 434         call_depth_(0),
 435         last_handle_before_deferred_block_(NULL),
 436         deferred_handles_head_(NULL) { }
 437
 438   ~HandleScopeImplementer() {
 439     DeleteArray(spare_);
 440   }
 441
 442   // Threading support for handle data.
 443   static int ArchiveSpacePerThread();
 444   char* RestoreThread(char* from);
 445   char* ArchiveThread(char* to);
 446   void FreeThreadResources();
 447
 448   // Garbage collection support.
 449   void Iterate(v8::internal::ObjectVisitor* v);
 450   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 451
 452
 453   inline internal::Object** GetSpareOrNewBlock();
 454   inline void DeleteExtensions(internal::Object** prev_limit);
 455
 456   inline void IncrementCallDepth() {call_depth_++;}
 457   inline void DecrementCallDepth() {call_depth_--;}
 458   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 459
 460   inline void EnterContext(Handle<Object> context);
 461   inline bool LeaveLastContext();
 462
 463   // Returns the last entered context or an empty handle if no
 464   // contexts have been entered.
 465   inline Handle<Object> LastEnteredContext();
 466
 467   inline void SaveContext(Context* context);
 468   inline Context* RestoreContext();
 469   inline bool HasSavedContexts();
 470
 471   inline List<internal::Object**>* blocks() { return &blocks_; }
 472   Isolate* isolate() const { return isolate_; }
 473
 474  private:
 475   void ResetAfterArchive() {
 476     blocks_.Initialize(0);
 477     entered_contexts_.Initialize(0);
 478     saved_contexts_.Initialize(0);
 479     spare_ = NULL;
 480     deferred_handles_head_ = NULL;
 481     last_handle_before_deferred_block_ = NULL;
 482     call_depth_ = 0;
 483   }
 484
 485   void Free() {
 486     ASSERT(blocks_.length() == 0);
 487     ASSERT(entered_contexts_.length() == 0);
 488     ASSERT(saved_contexts_.length() == 0);
 489     ASSERT(deferred_handles_head_ == NULL);
 490     blocks_.Free();
 491     entered_contexts_.Free();
 492     saved_contexts_.Free();
 493     if (spare_ != NULL) {
 494       DeleteArray(spare_);
 495       spare_ = NULL;
 496     }
 497     ASSERT(call_depth_ == 0);
 498   }
 499
 500   void BeginDeferredScope();
 501   DeferredHandles* Detach(Object** prev_limit);
 502   void DestroyDeferredHandles(DeferredHandles* handles);
 503
 504   Isolate* isolate_;
 505   List<internal::Object**> blocks_;
 506   // Used as a stack to keep track of entered contexts.
 507   List<Handle<Object> > entered_contexts_;
 508   // Used as a stack to keep track of saved contexts.
 509   List<Context*> saved_contexts_;
 510   Object** spare_;
 511   int call_depth_;
 512   Object** last_handle_before_deferred_block_;
 513   DeferredHandles* deferred_handles_head_;
 514   // This is only used for threading support.
 515   v8::ImplementationUtilities::HandleScopeData handle_scope_data_;
 516
 517   void IterateThis(ObjectVisitor* v);
 518   char* RestoreThreadHelper(char* from);
 519   char* ArchiveThreadHelper(char* to);
 520
 521   friend class DeferredHandles;
 522   friend class DeferredHandleScope;
 523
 524   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 525 };
 526
 527
 528 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 529
 530
 531 void HandleScopeImplementer::SaveContext(Context* context) {
 532   saved_contexts_.Add(context);
 533 }
 534
 535
 536 Context* HandleScopeImplementer::RestoreContext() {
 537   return saved_contexts_.RemoveLast();
 538 }
 539
 540
 541 bool HandleScopeImplementer::HasSavedContexts() {
 542   return !saved_contexts_.is_empty();
 543 }
 544
 545
 546 void HandleScopeImplementer::EnterContext(Handle<Object> context) {
 547   entered_contexts_.Add(context);
 548 }
 549
 550
 551 bool HandleScopeImplementer::LeaveLastContext() {
 552   if (entered_contexts_.is_empty()) return false;
 553   entered_contexts_.RemoveLast();
 554   return true;
 555 }
 556
 557
 558 Handle<Object> HandleScopeImplementer::LastEnteredContext() {
 559   if (entered_contexts_.is_empty()) return Handle<Object>::null();
 560   return entered_contexts_.last();
 561 }
 562
 563
 564 // If there's a spare block, use it for growing the current scope.
 565 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 566   internal::Object** block = (spare_ != NULL) ?
 567       spare_ :
 568       NewArray<internal::Object*>(kHandleBlockSize);
 569   spare_ = NULL;
 570   return block;
 571 }
 572
 573
 574 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 575   while (!blocks_.is_empty()) {
 576     internal::Object** block_start = blocks_.last();
 577     internal::Object** block_limit = block_start + kHandleBlockSize;
 578 #ifdef DEBUG
 579     // NoHandleAllocation may make the prev_limit to point inside the block.
 580     if (block_start <= prev_limit && prev_limit <= block_limit) break;
 581 #else
 582     if (prev_limit == block_limit) break;
 583 #endif
 584
 585     blocks_.RemoveLast();
 586 #ifdef DEBUG
 587     v8::ImplementationUtilities::ZapHandleRange(block_start, block_limit);
 588 #endif
 589     if (spare_ != NULL) {
 590       DeleteArray(spare_);
 591     }
 592     spare_ = block_start;
 593   }
 594   ASSERT((blocks_.is_empty() && prev_limit == NULL) ||
 595          (!blocks_.is_empty() && prev_limit != NULL));
 596 }
 597
 598
 599 class Testing {
 600  public:
 601   static v8::Testing::StressType stress_type() { return stress_type_; }
 602   static void set_stress_type(v8::Testing::StressType stress_type) {
 603     stress_type_ = stress_type;
 604   }
 605
 606  private:
 607   static v8::Testing::StressType stress_type_;
 608 };
 609
 610 } }  // namespace v8::internal
 611
 612 #endif  // V8_API_H_