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(Map, JSMap)                              \
 150   V(Set, JSSet)                              \
 151   V(ArrayBuffer, JSArrayBuffer)              \
 152   V(ArrayBufferView, JSArrayBufferView)      \
 153   V(TypedArray, JSTypedArray)                \
 154   V(Uint8Array, JSTypedArray)                \
 155   V(Uint8ClampedArray, JSTypedArray)         \
 156   V(Int8Array, JSTypedArray)                 \
 157   V(Uint16Array, JSTypedArray)               \
 158   V(Int16Array, JSTypedArray)                \
 159   V(Uint32Array, JSTypedArray)               \
 160   V(Int32Array, JSTypedArray)                \
 161   V(Float32Array, JSTypedArray)              \
 162   V(Float64Array, JSTypedArray)              \
 163   V(DataView, JSDataView)                    \
 164   V(SharedArrayBuffer, JSArrayBuffer)        \
 165   V(Name, Name)                              \
 166   V(String, String)                          \
 167   V(Symbol, Symbol)                          \
 168   V(Script, JSFunction)                      \
 169   V(UnboundScript, SharedFunctionInfo)       \
 170   V(Function, JSFunction)                    \
 171   V(Message, JSMessageObject)                \
 172   V(Context, Context)                        \
 173   V(External, Object)                        \
 174   V(StackTrace, JSArray)                     \
 175   V(StackFrame, JSObject)                    \
 176   V(NativeWeakMap, JSWeakMap)
 177
 178 class Utils {
 179  public:
 180   static inline bool ApiCheck(bool condition,
 181                               const char* location,
 182                               const char* message) {
 183     if (!condition) Utils::ReportApiFailure(location, message);
 184     return condition;
 185   }
 186
 187   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 188   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 189
 190   static inline Local<Context> ToLocal(
 191       v8::internal::Handle<v8::internal::Context> obj);
 192   static inline Local<Value> ToLocal(
 193       v8::internal::Handle<v8::internal::Object> obj);
 194   static inline Local<Function> ToLocal(
 195       v8::internal::Handle<v8::internal::JSFunction> obj);
 196   static inline Local<Name> ToLocal(
 197       v8::internal::Handle<v8::internal::Name> obj);
 198   static inline Local<String> ToLocal(
 199       v8::internal::Handle<v8::internal::String> obj);
 200   static inline Local<Symbol> ToLocal(
 201       v8::internal::Handle<v8::internal::Symbol> obj);
 202   static inline Local<RegExp> ToLocal(
 203       v8::internal::Handle<v8::internal::JSRegExp> obj);
 204   static inline Local<Object> ToLocal(
 205       v8::internal::Handle<v8::internal::JSObject> obj);
 206   static inline Local<Array> ToLocal(
 207       v8::internal::Handle<v8::internal::JSArray> obj);
 208   static inline Local<Map> ToLocal(
 209       v8::internal::Handle<v8::internal::JSMap> obj);
 210   static inline Local<Set> ToLocal(
 211       v8::internal::Handle<v8::internal::JSSet> obj);
 212   static inline Local<ArrayBuffer> ToLocal(
 213       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 214   static inline Local<ArrayBufferView> ToLocal(
 215       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 216   static inline Local<DataView> ToLocal(
 217       v8::internal::Handle<v8::internal::JSDataView> obj);
 218
 219   static inline Local<TypedArray> ToLocal(
 220       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 221   static inline Local<Uint8Array> ToLocalUint8Array(
 222       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 223   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 224       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 225   static inline Local<Int8Array> ToLocalInt8Array(
 226       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 227   static inline Local<Uint16Array> ToLocalUint16Array(
 228       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 229   static inline Local<Int16Array> ToLocalInt16Array(
 230       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 231   static inline Local<Uint32Array> ToLocalUint32Array(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233   static inline Local<Int32Array> ToLocalInt32Array(
 234       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 235   static inline Local<Float32Array> ToLocalFloat32Array(
 236       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 237   static inline Local<Float64Array> ToLocalFloat64Array(
 238       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 239
 240   static inline Local<SharedArrayBuffer> ToLocalShared(
 241       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 242
 243   static inline Local<Message> MessageToLocal(
 244       v8::internal::Handle<v8::internal::Object> obj);
 245   static inline Local<Promise> PromiseToLocal(
 246       v8::internal::Handle<v8::internal::JSObject> obj);
 247   static inline Local<StackTrace> StackTraceToLocal(
 248       v8::internal::Handle<v8::internal::JSArray> obj);
 249   static inline Local<StackFrame> StackFrameToLocal(
 250       v8::internal::Handle<v8::internal::JSObject> obj);
 251   static inline Local<Number> NumberToLocal(
 252       v8::internal::Handle<v8::internal::Object> obj);
 253   static inline Local<Integer> IntegerToLocal(
 254       v8::internal::Handle<v8::internal::Object> obj);
 255   static inline Local<Uint32> Uint32ToLocal(
 256       v8::internal::Handle<v8::internal::Object> obj);
 257   static inline Local<FunctionTemplate> ToLocal(
 258       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 259   static inline Local<ObjectTemplate> ToLocal(
 260       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 261   static inline Local<Signature> SignatureToLocal(
 262       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 263   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 264       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 265   static inline Local<TypeSwitch> ToLocal(
 266       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 267   static inline Local<External> ExternalToLocal(
 268       v8::internal::Handle<v8::internal::JSObject> obj);
 269   static inline Local<NativeWeakMap> NativeWeakMapToLocal(
 270       v8::internal::Handle<v8::internal::JSWeakMap> obj);
 271
 272 #define DECLARE_OPEN_HANDLE(From, To) \
 273   static inline v8::internal::Handle<v8::internal::To> \
 274       OpenHandle(const From* that, bool allow_empty_handle = false);
 275
 276 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 277
 278 #undef DECLARE_OPEN_HANDLE
 279
 280   template<class From, class To>
 281   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 282     DCHECK(obj.is_null() || !obj->IsTheHole());
 283     return Local<To>(reinterpret_cast<To*>(obj.location()));
 284   }
 285
 286   template <class T>
 287   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 288       const v8::Persistent<T>& persistent) {
 289     return v8::internal::Handle<v8::internal::Object>(
 290         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 291   }
 292
 293   template <class T>
 294   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 295       v8::Persistent<T>* persistent) {
 296     return OpenPersistent(*persistent);
 297   }
 298
 299   template <class From, class To>
 300   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 301     return OpenHandle(*handle);
 302   }
 303
 304  private:
 305   static void ReportApiFailure(const char* location, const char* message);
 306 };
 307
 308
 309 template <class T>
 310 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 311     v8::EscapableHandleScope* scope) {
 312   v8::internal::Handle<T> handle;
 313   if (!is_null()) {
 314     handle = *this;
 315   }
 316   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 317 }
 318
 319
 320 template <class T>
 321 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 322   return reinterpret_cast<T*>(obj.location());
 323 }
 324
 325 template <class T>
 326 inline v8::Local<T> ToApiHandle(
 327     v8::internal::Handle<v8::internal::Object> obj) {
 328   return Utils::Convert<v8::internal::Object, T>(obj);
 329 }
 330
 331
 332 template <class T>
 333 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
 334                     Local<T>* local) {
 335   v8::internal::Handle<v8::internal::Object> handle;
 336   if (maybe.ToHandle(&handle)) {
 337     *local = Utils::Convert<v8::internal::Object, T>(handle);
 338     return true;
 339   }
 340   return false;
 341 }
 342
 343
 344 // Implementations of ToLocal
 345
 346 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 347   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 348     return Convert<v8::internal::From, v8::To>(obj);  \
 349   }
 350
 351
 352 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
 353   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
 354       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
 355     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
 356     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
 357   }
 358
 359
 360 MAKE_TO_LOCAL(ToLocal, Context, Context)
 361 MAKE_TO_LOCAL(ToLocal, Object, Value)
 362 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 363 MAKE_TO_LOCAL(ToLocal, Name, Name)
 364 MAKE_TO_LOCAL(ToLocal, String, String)
 365 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 366 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 367 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 368 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 369 MAKE_TO_LOCAL(ToLocal, JSMap, Map)
 370 MAKE_TO_LOCAL(ToLocal, JSSet, Set)
 371 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 372 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 373 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 374 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 375 MAKE_TO_LOCAL(ToLocalShared, JSArrayBuffer, SharedArrayBuffer)
 376
 377 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 378
 379 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 380 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 381 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
 382 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 383 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 384 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 385 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 386 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 387 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 388 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 389 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 390 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 391 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 392 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
 393
 394 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 395 #undef MAKE_TO_LOCAL
 396
 397
 398 // Implementations of OpenHandle
 399
 400 #define MAKE_OPEN_HANDLE(From, To)                                             \
 401   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
 402       const v8::From* that, bool allow_empty_handle) {                         \
 403     DCHECK(allow_empty_handle || that != NULL);                                \
 404     DCHECK(that == NULL ||                                                     \
 405            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 406     return v8::internal::Handle<v8::internal::To>(                             \
 407         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
 408   }
 409
 410 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 411
 412 #undef MAKE_OPEN_HANDLE
 413 #undef OPEN_HANDLE_LIST
 414
 415
 416 namespace internal {
 417
 418 // Tracks string usage to help make better decisions when
 419 // externalizing strings.
 420 //
 421 // Implementation note: internally this class only tracks fresh
 422 // strings and keeps a single use counter for them.
 423 class StringTracker {
 424  public:
 425   // Records that the given string's characters were copied to some
 426   // external buffer. If this happens often we should honor
 427   // externalization requests for the string.
 428   void RecordWrite(Handle<String> string) {
 429     Address address = reinterpret_cast<Address>(*string);
 430     Address top = isolate_->heap()->NewSpaceTop();
 431     if (IsFreshString(address, top)) {
 432       IncrementUseCount(top);
 433     }
 434   }
 435
 436   // Estimates freshness and use frequency of the given string based
 437   // on how close it is to the new space top and the recorded usage
 438   // history.
 439   inline bool IsFreshUnusedString(Handle<String> string) {
 440     Address address = reinterpret_cast<Address>(*string);
 441     Address top = isolate_->heap()->NewSpaceTop();
 442     return IsFreshString(address, top) && IsUseCountLow(top);
 443   }
 444
 445  private:
 446   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 447
 448   static inline bool IsFreshString(Address string, Address top) {
 449     return top - kFreshnessLimit <= string && string <= top;
 450   }
 451
 452   inline bool IsUseCountLow(Address top) {
 453     if (last_top_ != top) return true;
 454     return use_count_ < kUseLimit;
 455   }
 456
 457   inline void IncrementUseCount(Address top) {
 458     if (last_top_ != top) {
 459       use_count_ = 0;
 460       last_top_ = top;
 461     }
 462     ++use_count_;
 463   }
 464
 465   // Single use counter shared by all fresh strings.
 466   int use_count_;
 467
 468   // Last new space top when the use count above was valid.
 469   Address last_top_;
 470
 471   Isolate* isolate_;
 472
 473   // How close to the new space top a fresh string has to be.
 474   static const int kFreshnessLimit = 1024;
 475
 476   // The number of uses required to consider a string useful.
 477   static const int kUseLimit = 32;
 478
 479   friend class Isolate;
 480
 481   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 482 };
 483
 484
 485 class DeferredHandles {
 486  public:
 487   ~DeferredHandles();
 488
 489  private:
 490   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 491       : next_(NULL),
 492         previous_(NULL),
 493         first_block_limit_(first_block_limit),
 494         isolate_(isolate) {
 495     isolate->LinkDeferredHandles(this);
 496   }
 497
 498   void Iterate(ObjectVisitor* v);
 499
 500   List<Object**> blocks_;
 501   DeferredHandles* next_;
 502   DeferredHandles* previous_;
 503   Object** first_block_limit_;
 504   Isolate* isolate_;
 505
 506   friend class HandleScopeImplementer;
 507   friend class Isolate;
 508 };
 509
 510
 511 // This class is here in order to be able to declare it a friend of
 512 // HandleScope.  Moving these methods to be members of HandleScope would be
 513 // neat in some ways, but it would expose internal implementation details in
 514 // our public header file, which is undesirable.
 515 //
 516 // An isolate has a single instance of this class to hold the current thread's
 517 // data. In multithreaded V8 programs this data is copied in and out of storage
 518 // so that the currently executing thread always has its own copy of this
 519 // data.
 520 class HandleScopeImplementer {
 521  public:
 522   explicit HandleScopeImplementer(Isolate* isolate)
 523       : isolate_(isolate),
 524         blocks_(0),
 525         entered_contexts_(0),
 526         saved_contexts_(0),
 527         spare_(NULL),
 528         call_depth_(0),
 529         last_handle_before_deferred_block_(NULL) { }
 530
 531   ~HandleScopeImplementer() {
 532     DeleteArray(spare_);
 533   }
 534
 535   // Threading support for handle data.
 536   static int ArchiveSpacePerThread();
 537   char* RestoreThread(char* from);
 538   char* ArchiveThread(char* to);
 539   void FreeThreadResources();
 540
 541   // Garbage collection support.
 542   void Iterate(v8::internal::ObjectVisitor* v);
 543   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 544
 545
 546   inline internal::Object** GetSpareOrNewBlock();
 547   inline void DeleteExtensions(internal::Object** prev_limit);
 548
 549   inline void IncrementCallDepth() {call_depth_++;}
 550   inline void DecrementCallDepth() {call_depth_--;}
 551   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 552
 553   inline void EnterContext(Handle<Context> context);
 554   inline void LeaveContext();
 555   inline bool LastEnteredContextWas(Handle<Context> context);
 556
 557   // Returns the last entered context or an empty handle if no
 558   // contexts have been entered.
 559   inline Handle<Context> LastEnteredContext();
 560
 561   inline void SaveContext(Context* context);
 562   inline Context* RestoreContext();
 563   inline bool HasSavedContexts();
 564
 565   inline List<internal::Object**>* blocks() { return &blocks_; }
 566   Isolate* isolate() const { return isolate_; }
 567
 568   void ReturnBlock(Object** block) {
 569     DCHECK(block != NULL);
 570     if (spare_ != NULL) DeleteArray(spare_);
 571     spare_ = block;
 572   }
 573
 574  private:
 575   void ResetAfterArchive() {
 576     blocks_.Initialize(0);
 577     entered_contexts_.Initialize(0);
 578     saved_contexts_.Initialize(0);
 579     spare_ = NULL;
 580     last_handle_before_deferred_block_ = NULL;
 581     call_depth_ = 0;
 582   }
 583
 584   void Free() {
 585     DCHECK(blocks_.length() == 0);
 586     DCHECK(entered_contexts_.length() == 0);
 587     DCHECK(saved_contexts_.length() == 0);
 588     blocks_.Free();
 589     entered_contexts_.Free();
 590     saved_contexts_.Free();
 591     if (spare_ != NULL) {
 592       DeleteArray(spare_);
 593       spare_ = NULL;
 594     }
 595     DCHECK(call_depth_ == 0);
 596   }
 597
 598   void BeginDeferredScope();
 599   DeferredHandles* Detach(Object** prev_limit);
 600
 601   Isolate* isolate_;
 602   List<internal::Object**> blocks_;
 603   // Used as a stack to keep track of entered contexts.
 604   List<Context*> entered_contexts_;
 605   // Used as a stack to keep track of saved contexts.
 606   List<Context*> saved_contexts_;
 607   Object** spare_;
 608   int call_depth_;
 609   Object** last_handle_before_deferred_block_;
 610   // This is only used for threading support.
 611   HandleScopeData handle_scope_data_;
 612
 613   void IterateThis(ObjectVisitor* v);
 614   char* RestoreThreadHelper(char* from);
 615   char* ArchiveThreadHelper(char* to);
 616
 617   friend class DeferredHandles;
 618   friend class DeferredHandleScope;
 619
 620   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 621 };
 622
 623
 624 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 625
 626
 627 void HandleScopeImplementer::SaveContext(Context* context) {
 628   saved_contexts_.Add(context);
 629 }
 630
 631
 632 Context* HandleScopeImplementer::RestoreContext() {
 633   return saved_contexts_.RemoveLast();
 634 }
 635
 636
 637 bool HandleScopeImplementer::HasSavedContexts() {
 638   return !saved_contexts_.is_empty();
 639 }
 640
 641
 642 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 643   entered_contexts_.Add(*context);
 644 }
 645
 646
 647 void HandleScopeImplementer::LeaveContext() {
 648   entered_contexts_.RemoveLast();
 649 }
 650
 651
 652 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 653   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 654 }
 655
 656
 657 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 658   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 659   return Handle<Context>(entered_contexts_.last());
 660 }
 661
 662
 663 // If there's a spare block, use it for growing the current scope.
 664 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 665   internal::Object** block = (spare_ != NULL) ?
 666       spare_ :
 667       NewArray<internal::Object*>(kHandleBlockSize);
 668   spare_ = NULL;
 669   return block;
 670 }
 671
 672
 673 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 674   while (!blocks_.is_empty()) {
 675     internal::Object** block_start = blocks_.last();
 676     internal::Object** block_limit = block_start + kHandleBlockSize;
 677
 678     // SealHandleScope may make the prev_limit to point inside the block.
 679     if (block_start <= prev_limit && prev_limit <= block_limit) {
 680 #ifdef ENABLE_HANDLE_ZAPPING
 681       internal::HandleScope::ZapRange(prev_limit, block_limit);
 682 #endif
 683       break;
 684     }
 685
 686     blocks_.RemoveLast();
 687 #ifdef ENABLE_HANDLE_ZAPPING
 688     internal::HandleScope::ZapRange(block_start, block_limit);
 689 #endif
 690     if (spare_ != NULL) {
 691       DeleteArray(spare_);
 692     }
 693     spare_ = block_start;
 694   }
 695   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 696          (!blocks_.is_empty() && prev_limit != NULL));
 697 }
 698
 699
 700 // Interceptor functions called from generated inline caches to notify
 701 // CPU profiler that external callbacks are invoked.
 702 void InvokeAccessorGetterCallback(
 703     v8::Local<v8::Name> property,
 704     const v8::PropertyCallbackInfo<v8::Value>& info,
 705     v8::AccessorNameGetterCallback getter);
 706
 707 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 708                             v8::FunctionCallback callback);
 709
 710 class Testing {
 711  public:
 712   static v8::Testing::StressType stress_type() { return stress_type_; }
 713   static void set_stress_type(v8::Testing::StressType stress_type) {
 714     stress_type_ = stress_type;
 715   }
 716
 717  private:
 718   static v8::Testing::StressType stress_type_;
 719 };
 720
 721 } }  // namespace v8::internal
 722
 723 #endif  // V8_API_H_