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   if (obj == v8::internal::Smi::FromInt(0)) return nullptr;
  99   return reinterpret_cast<T>(
 100       reinterpret_cast<intptr_t>(
 101           v8::internal::Foreign::cast(obj)->foreign_address()));
 102 }
 103
 104
 105 template <typename T>
 106 inline v8::internal::Handle<v8::internal::Object> FromCData(
 107     v8::internal::Isolate* isolate, T obj) {
 108   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 109   if (obj == nullptr) return handle(v8::internal::Smi::FromInt(0), isolate);
 110   return isolate->factory()->NewForeign(
 111       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 112 }
 113
 114
 115 class ApiFunction {
 116  public:
 117   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 118   v8::internal::Address address() { return addr_; }
 119  private:
 120   v8::internal::Address addr_;
 121 };
 122
 123
 124
 125 class RegisteredExtension {
 126  public:
 127   explicit RegisteredExtension(Extension* extension);
 128   static void Register(RegisteredExtension* that);
 129   static void UnregisterAll();
 130   Extension* extension() { return extension_; }
 131   RegisteredExtension* next() { return next_; }
 132   static RegisteredExtension* first_extension() { return first_extension_; }
 133  private:
 134   Extension* extension_;
 135   RegisteredExtension* next_;
 136   static RegisteredExtension* first_extension_;
 137 };
 138
 139
 140 #define OPEN_HANDLE_LIST(V)                  \
 141   V(Template, TemplateInfo)                  \
 142   V(FunctionTemplate, FunctionTemplateInfo)  \
 143   V(ObjectTemplate, ObjectTemplateInfo)      \
 144   V(Signature, FunctionTemplateInfo)         \
 145   V(AccessorSignature, FunctionTemplateInfo) \
 146   V(TypeSwitch, TypeSwitchInfo)              \
 147   V(Data, Object)                            \
 148   V(RegExp, JSRegExp)                        \
 149   V(Object, JSObject)                        \
 150   V(Array, JSArray)                          \
 151   V(Map, JSMap)                              \
 152   V(Set, JSSet)                              \
 153   V(ArrayBuffer, JSArrayBuffer)              \
 154   V(ArrayBufferView, JSArrayBufferView)      \
 155   V(TypedArray, JSTypedArray)                \
 156   V(Uint8Array, JSTypedArray)                \
 157   V(Uint8ClampedArray, JSTypedArray)         \
 158   V(Int8Array, JSTypedArray)                 \
 159   V(Uint16Array, JSTypedArray)               \
 160   V(Int16Array, JSTypedArray)                \
 161   V(Uint32Array, JSTypedArray)               \
 162   V(Int32Array, JSTypedArray)                \
 163   V(Float32Array, JSTypedArray)              \
 164   V(Float64Array, JSTypedArray)              \
 165   V(DataView, JSDataView)                    \
 166   V(SharedArrayBuffer, JSArrayBuffer)        \
 167   V(Name, Name)                              \
 168   V(String, String)                          \
 169   V(Symbol, Symbol)                          \
 170   V(Script, JSFunction)                      \
 171   V(UnboundScript, SharedFunctionInfo)       \
 172   V(Function, JSFunction)                    \
 173   V(Message, JSMessageObject)                \
 174   V(Context, Context)                        \
 175   V(External, Object)                        \
 176   V(StackTrace, JSArray)                     \
 177   V(StackFrame, JSObject)                    \
 178   V(NativeWeakMap, JSWeakMap)
 179
 180 class Utils {
 181  public:
 182   static inline bool ApiCheck(bool condition,
 183                               const char* location,
 184                               const char* message) {
 185     if (!condition) Utils::ReportApiFailure(location, message);
 186     return condition;
 187   }
 188
 189   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 190   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 191
 192   static inline Local<Context> ToLocal(
 193       v8::internal::Handle<v8::internal::Context> obj);
 194   static inline Local<Value> ToLocal(
 195       v8::internal::Handle<v8::internal::Object> obj);
 196   static inline Local<Function> ToLocal(
 197       v8::internal::Handle<v8::internal::JSFunction> obj);
 198   static inline Local<Name> ToLocal(
 199       v8::internal::Handle<v8::internal::Name> obj);
 200   static inline Local<String> ToLocal(
 201       v8::internal::Handle<v8::internal::String> obj);
 202   static inline Local<Symbol> ToLocal(
 203       v8::internal::Handle<v8::internal::Symbol> obj);
 204   static inline Local<RegExp> ToLocal(
 205       v8::internal::Handle<v8::internal::JSRegExp> obj);
 206   static inline Local<Object> ToLocal(
 207       v8::internal::Handle<v8::internal::JSObject> obj);
 208   static inline Local<Array> ToLocal(
 209       v8::internal::Handle<v8::internal::JSArray> obj);
 210   static inline Local<Map> ToLocal(
 211       v8::internal::Handle<v8::internal::JSMap> obj);
 212   static inline Local<Set> ToLocal(
 213       v8::internal::Handle<v8::internal::JSSet> obj);
 214   static inline Local<ArrayBuffer> ToLocal(
 215       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 216   static inline Local<ArrayBufferView> ToLocal(
 217       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 218   static inline Local<DataView> ToLocal(
 219       v8::internal::Handle<v8::internal::JSDataView> obj);
 220
 221   static inline Local<TypedArray> ToLocal(
 222       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 223   static inline Local<Uint8Array> ToLocalUint8Array(
 224       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 225   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 226       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 227   static inline Local<Int8Array> ToLocalInt8Array(
 228       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 229   static inline Local<Uint16Array> ToLocalUint16Array(
 230       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 231   static inline Local<Int16Array> ToLocalInt16Array(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233   static inline Local<Uint32Array> ToLocalUint32Array(
 234       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 235   static inline Local<Int32Array> ToLocalInt32Array(
 236       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 237   static inline Local<Float32Array> ToLocalFloat32Array(
 238       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 239   static inline Local<Float64Array> ToLocalFloat64Array(
 240       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 241
 242   static inline Local<SharedArrayBuffer> ToLocalShared(
 243       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 244
 245   static inline Local<Message> MessageToLocal(
 246       v8::internal::Handle<v8::internal::Object> obj);
 247   static inline Local<Promise> PromiseToLocal(
 248       v8::internal::Handle<v8::internal::JSObject> obj);
 249   static inline Local<StackTrace> StackTraceToLocal(
 250       v8::internal::Handle<v8::internal::JSArray> obj);
 251   static inline Local<StackFrame> StackFrameToLocal(
 252       v8::internal::Handle<v8::internal::JSObject> obj);
 253   static inline Local<Number> NumberToLocal(
 254       v8::internal::Handle<v8::internal::Object> obj);
 255   static inline Local<Integer> IntegerToLocal(
 256       v8::internal::Handle<v8::internal::Object> obj);
 257   static inline Local<Uint32> Uint32ToLocal(
 258       v8::internal::Handle<v8::internal::Object> obj);
 259   static inline Local<FunctionTemplate> ToLocal(
 260       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 261   static inline Local<ObjectTemplate> ToLocal(
 262       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 263   static inline Local<Signature> SignatureToLocal(
 264       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 265   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 266       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 267   static inline Local<TypeSwitch> ToLocal(
 268       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 269   static inline Local<External> ExternalToLocal(
 270       v8::internal::Handle<v8::internal::JSObject> obj);
 271   static inline Local<NativeWeakMap> NativeWeakMapToLocal(
 272       v8::internal::Handle<v8::internal::JSWeakMap> obj);
 273
 274 #define DECLARE_OPEN_HANDLE(From, To) \
 275   static inline v8::internal::Handle<v8::internal::To> \
 276       OpenHandle(const From* that, bool allow_empty_handle = false);
 277
 278 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 279
 280 #undef DECLARE_OPEN_HANDLE
 281
 282   template<class From, class To>
 283   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 284     DCHECK(obj.is_null() || !obj->IsTheHole());
 285     return Local<To>(reinterpret_cast<To*>(obj.location()));
 286   }
 287
 288   template <class T>
 289   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 290       const v8::Persistent<T>& persistent) {
 291     return v8::internal::Handle<v8::internal::Object>(
 292         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 293   }
 294
 295   template <class T>
 296   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 297       v8::Persistent<T>* persistent) {
 298     return OpenPersistent(*persistent);
 299   }
 300
 301   template <class From, class To>
 302   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 303     return OpenHandle(*handle);
 304   }
 305
 306  private:
 307   static void ReportApiFailure(const char* location, const char* message);
 308 };
 309
 310
 311 template <class T>
 312 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 313     v8::EscapableHandleScope* scope) {
 314   v8::internal::Handle<T> handle;
 315   if (!is_null()) {
 316     handle = *this;
 317   }
 318   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 319 }
 320
 321
 322 template <class T>
 323 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 324   return reinterpret_cast<T*>(obj.location());
 325 }
 326
 327 template <class T>
 328 inline v8::Local<T> ToApiHandle(
 329     v8::internal::Handle<v8::internal::Object> obj) {
 330   return Utils::Convert<v8::internal::Object, T>(obj);
 331 }
 332
 333
 334 template <class T>
 335 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
 336                     Local<T>* local) {
 337   v8::internal::Handle<v8::internal::Object> handle;
 338   if (maybe.ToHandle(&handle)) {
 339     *local = Utils::Convert<v8::internal::Object, T>(handle);
 340     return true;
 341   }
 342   return false;
 343 }
 344
 345
 346 // Implementations of ToLocal
 347
 348 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 349   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 350     return Convert<v8::internal::From, v8::To>(obj);  \
 351   }
 352
 353
 354 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
 355   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
 356       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
 357     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
 358     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
 359   }
 360
 361
 362 MAKE_TO_LOCAL(ToLocal, Context, Context)
 363 MAKE_TO_LOCAL(ToLocal, Object, Value)
 364 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 365 MAKE_TO_LOCAL(ToLocal, Name, Name)
 366 MAKE_TO_LOCAL(ToLocal, String, String)
 367 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 368 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 369 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 370 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 371 MAKE_TO_LOCAL(ToLocal, JSMap, Map)
 372 MAKE_TO_LOCAL(ToLocal, JSSet, Set)
 373 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 374 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 375 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 376 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 377 MAKE_TO_LOCAL(ToLocalShared, JSArrayBuffer, SharedArrayBuffer)
 378
 379 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 380
 381 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 382 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 383 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
 384 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 385 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 386 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 387 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 388 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 389 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 390 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 391 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 392 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 393 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 394 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
 395
 396 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 397 #undef MAKE_TO_LOCAL
 398
 399
 400 // Implementations of OpenHandle
 401
 402 #define MAKE_OPEN_HANDLE(From, To)                                             \
 403   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
 404       const v8::From* that, bool allow_empty_handle) {                         \
 405     DCHECK(allow_empty_handle || that != NULL);                                \
 406     DCHECK(that == NULL ||                                                     \
 407            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 408     return v8::internal::Handle<v8::internal::To>(                             \
 409         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
 410   }
 411
 412 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 413
 414 #undef MAKE_OPEN_HANDLE
 415 #undef OPEN_HANDLE_LIST
 416
 417
 418 namespace internal {
 419
 420 // Tracks string usage to help make better decisions when
 421 // externalizing strings.
 422 //
 423 // Implementation note: internally this class only tracks fresh
 424 // strings and keeps a single use counter for them.
 425 class StringTracker {
 426  public:
 427   // Records that the given string's characters were copied to some
 428   // external buffer. If this happens often we should honor
 429   // externalization requests for the string.
 430   void RecordWrite(Handle<String> string) {
 431     Address address = reinterpret_cast<Address>(*string);
 432     Address top = isolate_->heap()->NewSpaceTop();
 433     if (IsFreshString(address, top)) {
 434       IncrementUseCount(top);
 435     }
 436   }
 437
 438   // Estimates freshness and use frequency of the given string based
 439   // on how close it is to the new space top and the recorded usage
 440   // history.
 441   inline bool IsFreshUnusedString(Handle<String> string) {
 442     Address address = reinterpret_cast<Address>(*string);
 443     Address top = isolate_->heap()->NewSpaceTop();
 444     return IsFreshString(address, top) && IsUseCountLow(top);
 445   }
 446
 447  private:
 448   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 449
 450   static inline bool IsFreshString(Address string, Address top) {
 451     return top - kFreshnessLimit <= string && string <= top;
 452   }
 453
 454   inline bool IsUseCountLow(Address top) {
 455     if (last_top_ != top) return true;
 456     return use_count_ < kUseLimit;
 457   }
 458
 459   inline void IncrementUseCount(Address top) {
 460     if (last_top_ != top) {
 461       use_count_ = 0;
 462       last_top_ = top;
 463     }
 464     ++use_count_;
 465   }
 466
 467   // Single use counter shared by all fresh strings.
 468   int use_count_;
 469
 470   // Last new space top when the use count above was valid.
 471   Address last_top_;
 472
 473   Isolate* isolate_;
 474
 475   // How close to the new space top a fresh string has to be.
 476   static const int kFreshnessLimit = 1024;
 477
 478   // The number of uses required to consider a string useful.
 479   static const int kUseLimit = 32;
 480
 481   friend class Isolate;
 482
 483   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 484 };
 485
 486
 487 class DeferredHandles {
 488  public:
 489   ~DeferredHandles();
 490
 491  private:
 492   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 493       : next_(NULL),
 494         previous_(NULL),
 495         first_block_limit_(first_block_limit),
 496         isolate_(isolate) {
 497     isolate->LinkDeferredHandles(this);
 498   }
 499
 500   void Iterate(ObjectVisitor* v);
 501
 502   List<Object**> blocks_;
 503   DeferredHandles* next_;
 504   DeferredHandles* previous_;
 505   Object** first_block_limit_;
 506   Isolate* isolate_;
 507
 508   friend class HandleScopeImplementer;
 509   friend class Isolate;
 510 };
 511
 512
 513 // This class is here in order to be able to declare it a friend of
 514 // HandleScope.  Moving these methods to be members of HandleScope would be
 515 // neat in some ways, but it would expose internal implementation details in
 516 // our public header file, which is undesirable.
 517 //
 518 // An isolate has a single instance of this class to hold the current thread's
 519 // data. In multithreaded V8 programs this data is copied in and out of storage
 520 // so that the currently executing thread always has its own copy of this
 521 // data.
 522 class HandleScopeImplementer {
 523  public:
 524   explicit HandleScopeImplementer(Isolate* isolate)
 525       : isolate_(isolate),
 526         blocks_(0),
 527         entered_contexts_(0),
 528         saved_contexts_(0),
 529         spare_(NULL),
 530         call_depth_(0),
 531         last_handle_before_deferred_block_(NULL) { }
 532
 533   ~HandleScopeImplementer() {
 534     DeleteArray(spare_);
 535   }
 536
 537   // Threading support for handle data.
 538   static int ArchiveSpacePerThread();
 539   char* RestoreThread(char* from);
 540   char* ArchiveThread(char* to);
 541   void FreeThreadResources();
 542
 543   // Garbage collection support.
 544   void Iterate(v8::internal::ObjectVisitor* v);
 545   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 546
 547
 548   inline internal::Object** GetSpareOrNewBlock();
 549   inline void DeleteExtensions(internal::Object** prev_limit);
 550
 551   inline void IncrementCallDepth() {call_depth_++;}
 552   inline void DecrementCallDepth() {call_depth_--;}
 553   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 554
 555   inline void EnterContext(Handle<Context> context);
 556   inline void LeaveContext();
 557   inline bool LastEnteredContextWas(Handle<Context> context);
 558
 559   // Returns the last entered context or an empty handle if no
 560   // contexts have been entered.
 561   inline Handle<Context> LastEnteredContext();
 562
 563   inline void SaveContext(Context* context);
 564   inline Context* RestoreContext();
 565   inline bool HasSavedContexts();
 566
 567   inline List<internal::Object**>* blocks() { return &blocks_; }
 568   Isolate* isolate() const { return isolate_; }
 569
 570   void ReturnBlock(Object** block) {
 571     DCHECK(block != NULL);
 572     if (spare_ != NULL) DeleteArray(spare_);
 573     spare_ = block;
 574   }
 575
 576  private:
 577   void ResetAfterArchive() {
 578     blocks_.Initialize(0);
 579     entered_contexts_.Initialize(0);
 580     saved_contexts_.Initialize(0);
 581     spare_ = NULL;
 582     last_handle_before_deferred_block_ = NULL;
 583     call_depth_ = 0;
 584   }
 585
 586   void Free() {
 587     DCHECK(blocks_.length() == 0);
 588     DCHECK(entered_contexts_.length() == 0);
 589     DCHECK(saved_contexts_.length() == 0);
 590     blocks_.Free();
 591     entered_contexts_.Free();
 592     saved_contexts_.Free();
 593     if (spare_ != NULL) {
 594       DeleteArray(spare_);
 595       spare_ = NULL;
 596     }
 597     DCHECK(call_depth_ == 0);
 598   }
 599
 600   void BeginDeferredScope();
 601   DeferredHandles* Detach(Object** prev_limit);
 602
 603   Isolate* isolate_;
 604   List<internal::Object**> blocks_;
 605   // Used as a stack to keep track of entered contexts.
 606   List<Context*> entered_contexts_;
 607   // Used as a stack to keep track of saved contexts.
 608   List<Context*> saved_contexts_;
 609   Object** spare_;
 610   int call_depth_;
 611   Object** last_handle_before_deferred_block_;
 612   // This is only used for threading support.
 613   HandleScopeData handle_scope_data_;
 614
 615   void IterateThis(ObjectVisitor* v);
 616   char* RestoreThreadHelper(char* from);
 617   char* ArchiveThreadHelper(char* to);
 618
 619   friend class DeferredHandles;
 620   friend class DeferredHandleScope;
 621
 622   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 623 };
 624
 625
 626 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 627
 628
 629 void HandleScopeImplementer::SaveContext(Context* context) {
 630   saved_contexts_.Add(context);
 631 }
 632
 633
 634 Context* HandleScopeImplementer::RestoreContext() {
 635   return saved_contexts_.RemoveLast();
 636 }
 637
 638
 639 bool HandleScopeImplementer::HasSavedContexts() {
 640   return !saved_contexts_.is_empty();
 641 }
 642
 643
 644 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 645   entered_contexts_.Add(*context);
 646 }
 647
 648
 649 void HandleScopeImplementer::LeaveContext() {
 650   entered_contexts_.RemoveLast();
 651 }
 652
 653
 654 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 655   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 656 }
 657
 658
 659 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 660   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 661   return Handle<Context>(entered_contexts_.last());
 662 }
 663
 664
 665 // If there's a spare block, use it for growing the current scope.
 666 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 667   internal::Object** block = (spare_ != NULL) ?
 668       spare_ :
 669       NewArray<internal::Object*>(kHandleBlockSize);
 670   spare_ = NULL;
 671   return block;
 672 }
 673
 674
 675 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 676   while (!blocks_.is_empty()) {
 677     internal::Object** block_start = blocks_.last();
 678     internal::Object** block_limit = block_start + kHandleBlockSize;
 679
 680     // SealHandleScope may make the prev_limit to point inside the block.
 681     if (block_start <= prev_limit && prev_limit <= block_limit) {
 682 #ifdef ENABLE_HANDLE_ZAPPING
 683       internal::HandleScope::ZapRange(prev_limit, block_limit);
 684 #endif
 685       break;
 686     }
 687
 688     blocks_.RemoveLast();
 689 #ifdef ENABLE_HANDLE_ZAPPING
 690     internal::HandleScope::ZapRange(block_start, block_limit);
 691 #endif
 692     if (spare_ != NULL) {
 693       DeleteArray(spare_);
 694     }
 695     spare_ = block_start;
 696   }
 697   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 698          (!blocks_.is_empty() && prev_limit != NULL));
 699 }
 700
 701
 702 // Interceptor functions called from generated inline caches to notify
 703 // CPU profiler that external callbacks are invoked.
 704 void InvokeAccessorGetterCallback(
 705     v8::Local<v8::Name> property,
 706     const v8::PropertyCallbackInfo<v8::Value>& info,
 707     v8::AccessorNameGetterCallback getter);
 708
 709 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 710                             v8::FunctionCallback callback);
 711
 712 class Testing {
 713  public:
 714   static v8::Testing::StressType stress_type() { return stress_type_; }
 715   static void set_stress_type(v8::Testing::StressType stress_type) {
 716     stress_type_ = stress_type;
 717   }
 718
 719  private:
 720   static v8::Testing::StressType stress_type_;
 721 };
 722
 723 } }  // namespace v8::internal
 724
 725 #endif  // V8_API_H_