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 template <class T>
 323 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
 324                     Local<T>* local) {
 325   v8::internal::Handle<v8::internal::Object> handle;
 326   if (maybe.ToHandle(&handle)) {
 327     *local = Utils::Convert<v8::internal::Object, T>(handle);
 328     return true;
 329   }
 330   return false;
 331 }
 332
 333
 334 // Implementations of ToLocal
 335
 336 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 337   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 338     return Convert<v8::internal::From, v8::To>(obj);  \
 339   }
 340
 341
 342 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
 343   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
 344       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
 345     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
 346     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
 347   }
 348
 349
 350 MAKE_TO_LOCAL(ToLocal, Context, Context)
 351 MAKE_TO_LOCAL(ToLocal, Object, Value)
 352 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 353 MAKE_TO_LOCAL(ToLocal, Name, Name)
 354 MAKE_TO_LOCAL(ToLocal, String, String)
 355 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 356 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 357 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 358 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 359 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 360 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 361 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 362 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 363
 364 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 365
 366 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 367 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 368 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
 369 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 370 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 371 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 372 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 373 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 374 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 375 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 376 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 377 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 378 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 379 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
 380
 381 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 382 #undef MAKE_TO_LOCAL
 383
 384
 385 // Implementations of OpenHandle
 386
 387 #define MAKE_OPEN_HANDLE(From, To)                                             \
 388   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
 389       const v8::From* that, bool allow_empty_handle) {                         \
 390     DCHECK(allow_empty_handle || that != NULL);                                \
 391     DCHECK(that == NULL ||                                                     \
 392            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 393     return v8::internal::Handle<v8::internal::To>(                             \
 394         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
 395   }
 396
 397 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 398
 399 #undef MAKE_OPEN_HANDLE
 400 #undef OPEN_HANDLE_LIST
 401
 402
 403 namespace internal {
 404
 405 // Tracks string usage to help make better decisions when
 406 // externalizing strings.
 407 //
 408 // Implementation note: internally this class only tracks fresh
 409 // strings and keeps a single use counter for them.
 410 class StringTracker {
 411  public:
 412   // Records that the given string's characters were copied to some
 413   // external buffer. If this happens often we should honor
 414   // externalization requests for the string.
 415   void RecordWrite(Handle<String> string) {
 416     Address address = reinterpret_cast<Address>(*string);
 417     Address top = isolate_->heap()->NewSpaceTop();
 418     if (IsFreshString(address, top)) {
 419       IncrementUseCount(top);
 420     }
 421   }
 422
 423   // Estimates freshness and use frequency of the given string based
 424   // on how close it is to the new space top and the recorded usage
 425   // history.
 426   inline bool IsFreshUnusedString(Handle<String> string) {
 427     Address address = reinterpret_cast<Address>(*string);
 428     Address top = isolate_->heap()->NewSpaceTop();
 429     return IsFreshString(address, top) && IsUseCountLow(top);
 430   }
 431
 432  private:
 433   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 434
 435   static inline bool IsFreshString(Address string, Address top) {
 436     return top - kFreshnessLimit <= string && string <= top;
 437   }
 438
 439   inline bool IsUseCountLow(Address top) {
 440     if (last_top_ != top) return true;
 441     return use_count_ < kUseLimit;
 442   }
 443
 444   inline void IncrementUseCount(Address top) {
 445     if (last_top_ != top) {
 446       use_count_ = 0;
 447       last_top_ = top;
 448     }
 449     ++use_count_;
 450   }
 451
 452   // Single use counter shared by all fresh strings.
 453   int use_count_;
 454
 455   // Last new space top when the use count above was valid.
 456   Address last_top_;
 457
 458   Isolate* isolate_;
 459
 460   // How close to the new space top a fresh string has to be.
 461   static const int kFreshnessLimit = 1024;
 462
 463   // The number of uses required to consider a string useful.
 464   static const int kUseLimit = 32;
 465
 466   friend class Isolate;
 467
 468   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 469 };
 470
 471
 472 class DeferredHandles {
 473  public:
 474   ~DeferredHandles();
 475
 476  private:
 477   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 478       : next_(NULL),
 479         previous_(NULL),
 480         first_block_limit_(first_block_limit),
 481         isolate_(isolate) {
 482     isolate->LinkDeferredHandles(this);
 483   }
 484
 485   void Iterate(ObjectVisitor* v);
 486
 487   List<Object**> blocks_;
 488   DeferredHandles* next_;
 489   DeferredHandles* previous_;
 490   Object** first_block_limit_;
 491   Isolate* isolate_;
 492
 493   friend class HandleScopeImplementer;
 494   friend class Isolate;
 495 };
 496
 497
 498 // This class is here in order to be able to declare it a friend of
 499 // HandleScope.  Moving these methods to be members of HandleScope would be
 500 // neat in some ways, but it would expose internal implementation details in
 501 // our public header file, which is undesirable.
 502 //
 503 // An isolate has a single instance of this class to hold the current thread's
 504 // data. In multithreaded V8 programs this data is copied in and out of storage
 505 // so that the currently executing thread always has its own copy of this
 506 // data.
 507 class HandleScopeImplementer {
 508  public:
 509   explicit HandleScopeImplementer(Isolate* isolate)
 510       : isolate_(isolate),
 511         blocks_(0),
 512         entered_contexts_(0),
 513         saved_contexts_(0),
 514         spare_(NULL),
 515         call_depth_(0),
 516         last_handle_before_deferred_block_(NULL) { }
 517
 518   ~HandleScopeImplementer() {
 519     DeleteArray(spare_);
 520   }
 521
 522   // Threading support for handle data.
 523   static int ArchiveSpacePerThread();
 524   char* RestoreThread(char* from);
 525   char* ArchiveThread(char* to);
 526   void FreeThreadResources();
 527
 528   // Garbage collection support.
 529   void Iterate(v8::internal::ObjectVisitor* v);
 530   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 531
 532
 533   inline internal::Object** GetSpareOrNewBlock();
 534   inline void DeleteExtensions(internal::Object** prev_limit);
 535
 536   inline void IncrementCallDepth() {call_depth_++;}
 537   inline void DecrementCallDepth() {call_depth_--;}
 538   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 539
 540   inline void EnterContext(Handle<Context> context);
 541   inline void LeaveContext();
 542   inline bool LastEnteredContextWas(Handle<Context> context);
 543
 544   // Returns the last entered context or an empty handle if no
 545   // contexts have been entered.
 546   inline Handle<Context> LastEnteredContext();
 547
 548   inline void SaveContext(Context* context);
 549   inline Context* RestoreContext();
 550   inline bool HasSavedContexts();
 551
 552   inline List<internal::Object**>* blocks() { return &blocks_; }
 553   Isolate* isolate() const { return isolate_; }
 554
 555   void ReturnBlock(Object** block) {
 556     DCHECK(block != NULL);
 557     if (spare_ != NULL) DeleteArray(spare_);
 558     spare_ = block;
 559   }
 560
 561  private:
 562   void ResetAfterArchive() {
 563     blocks_.Initialize(0);
 564     entered_contexts_.Initialize(0);
 565     saved_contexts_.Initialize(0);
 566     spare_ = NULL;
 567     last_handle_before_deferred_block_ = NULL;
 568     call_depth_ = 0;
 569   }
 570
 571   void Free() {
 572     DCHECK(blocks_.length() == 0);
 573     DCHECK(entered_contexts_.length() == 0);
 574     DCHECK(saved_contexts_.length() == 0);
 575     blocks_.Free();
 576     entered_contexts_.Free();
 577     saved_contexts_.Free();
 578     if (spare_ != NULL) {
 579       DeleteArray(spare_);
 580       spare_ = NULL;
 581     }
 582     DCHECK(call_depth_ == 0);
 583   }
 584
 585   void BeginDeferredScope();
 586   DeferredHandles* Detach(Object** prev_limit);
 587
 588   Isolate* isolate_;
 589   List<internal::Object**> blocks_;
 590   // Used as a stack to keep track of entered contexts.
 591   List<Context*> entered_contexts_;
 592   // Used as a stack to keep track of saved contexts.
 593   List<Context*> saved_contexts_;
 594   Object** spare_;
 595   int call_depth_;
 596   Object** last_handle_before_deferred_block_;
 597   // This is only used for threading support.
 598   HandleScopeData handle_scope_data_;
 599
 600   void IterateThis(ObjectVisitor* v);
 601   char* RestoreThreadHelper(char* from);
 602   char* ArchiveThreadHelper(char* to);
 603
 604   friend class DeferredHandles;
 605   friend class DeferredHandleScope;
 606
 607   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 608 };
 609
 610
 611 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 612
 613
 614 void HandleScopeImplementer::SaveContext(Context* context) {
 615   saved_contexts_.Add(context);
 616 }
 617
 618
 619 Context* HandleScopeImplementer::RestoreContext() {
 620   return saved_contexts_.RemoveLast();
 621 }
 622
 623
 624 bool HandleScopeImplementer::HasSavedContexts() {
 625   return !saved_contexts_.is_empty();
 626 }
 627
 628
 629 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 630   entered_contexts_.Add(*context);
 631 }
 632
 633
 634 void HandleScopeImplementer::LeaveContext() {
 635   entered_contexts_.RemoveLast();
 636 }
 637
 638
 639 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 640   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 641 }
 642
 643
 644 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 645   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 646   return Handle<Context>(entered_contexts_.last());
 647 }
 648
 649
 650 // If there's a spare block, use it for growing the current scope.
 651 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 652   internal::Object** block = (spare_ != NULL) ?
 653       spare_ :
 654       NewArray<internal::Object*>(kHandleBlockSize);
 655   spare_ = NULL;
 656   return block;
 657 }
 658
 659
 660 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 661   while (!blocks_.is_empty()) {
 662     internal::Object** block_start = blocks_.last();
 663     internal::Object** block_limit = block_start + kHandleBlockSize;
 664
 665     // SealHandleScope may make the prev_limit to point inside the block.
 666     if (block_start <= prev_limit && prev_limit <= block_limit) {
 667 #ifdef ENABLE_HANDLE_ZAPPING
 668       internal::HandleScope::ZapRange(prev_limit, block_limit);
 669 #endif
 670       break;
 671     }
 672
 673     blocks_.RemoveLast();
 674 #ifdef ENABLE_HANDLE_ZAPPING
 675     internal::HandleScope::ZapRange(block_start, block_limit);
 676 #endif
 677     if (spare_ != NULL) {
 678       DeleteArray(spare_);
 679     }
 680     spare_ = block_start;
 681   }
 682   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 683          (!blocks_.is_empty() && prev_limit != NULL));
 684 }
 685
 686
 687 // Interceptor functions called from generated inline caches to notify
 688 // CPU profiler that external callbacks are invoked.
 689 void InvokeAccessorGetterCallback(
 690     v8::Local<v8::Name> property,
 691     const v8::PropertyCallbackInfo<v8::Value>& info,
 692     v8::AccessorNameGetterCallback getter);
 693
 694 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 695                             v8::FunctionCallback callback);
 696
 697 class Testing {
 698  public:
 699   static v8::Testing::StressType stress_type() { return stress_type_; }
 700   static void set_stress_type(v8::Testing::StressType stress_type) {
 701     stress_type_ = stress_type;
 702   }
 703
 704  private:
 705   static v8::Testing::StressType stress_type_;
 706 };
 707
 708 } }  // namespace v8::internal
 709
 710 #endif  // V8_API_H_