src/api.h

   1 // Copyright 2012 the V8 project authors. All rights reserved.
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   7 //       notice, this list of conditions and the following disclaimer.
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  27
  28 #ifndef V8_API_H_
  29 #define V8_API_H_
  30
  31 #include "v8.h"
  32
  33 #include "../include/v8-testing.h"
  34 #include "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(
 129     v8::internal::Isolate* isolate, T obj) {
 130   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 131   return isolate->factory()->NewForeign(
 132       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 133 }
 134
 135
 136 class ApiFunction {
 137  public:
 138   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 139   v8::internal::Address address() { return addr_; }
 140  private:
 141   v8::internal::Address addr_;
 142 };
 143
 144
 145
 146 class RegisteredExtension {
 147  public:
 148   explicit RegisteredExtension(Extension* extension);
 149   static void Register(RegisteredExtension* that);
 150   static void UnregisterAll();
 151   Extension* extension() { return extension_; }
 152   RegisteredExtension* next() { return next_; }
 153   static RegisteredExtension* first_extension() { return first_extension_; }
 154  private:
 155   Extension* extension_;
 156   RegisteredExtension* next_;
 157   static RegisteredExtension* first_extension_;
 158 };
 159
 160
 161 #define OPEN_HANDLE_LIST(V)                    \
 162   V(Template, TemplateInfo)                    \
 163   V(FunctionTemplate, FunctionTemplateInfo)    \
 164   V(ObjectTemplate, ObjectTemplateInfo)        \
 165   V(Signature, SignatureInfo)                  \
 166   V(AccessorSignature, FunctionTemplateInfo)   \
 167   V(TypeSwitch, TypeSwitchInfo)                \
 168   V(Data, Object)                              \
 169   V(RegExp, JSRegExp)                          \
 170   V(Object, JSObject)                          \
 171   V(Array, JSArray)                            \
 172   V(ArrayBuffer, JSArrayBuffer)                \
 173   V(ArrayBufferView, JSArrayBufferView)        \
 174   V(TypedArray, JSTypedArray)                  \
 175   V(Uint8Array, JSTypedArray)                  \
 176   V(Uint8ClampedArray, JSTypedArray)           \
 177   V(Int8Array, JSTypedArray)                   \
 178   V(Uint16Array, JSTypedArray)                 \
 179   V(Int16Array, JSTypedArray)                  \
 180   V(Uint32Array, JSTypedArray)                 \
 181   V(Int32Array, JSTypedArray)                  \
 182   V(Float32Array, JSTypedArray)                \
 183   V(Float64Array, JSTypedArray)                \
 184   V(DataView, JSDataView)                      \
 185   V(String, String)                            \
 186   V(Symbol, Symbol)                            \
 187   V(Script, Object)                            \
 188   V(Function, JSFunction)                      \
 189   V(Message, JSObject)                         \
 190   V(Context, Context)                          \
 191   V(External, Foreign)                         \
 192   V(StackTrace, JSArray)                       \
 193   V(StackFrame, JSObject)                      \
 194   V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 195
 196
 197 class Utils {
 198  public:
 199   static bool ReportApiFailure(const char* location, const char* message);
 200
 201   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 202   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 203
 204   static inline Local<Context> ToLocal(
 205       v8::internal::Handle<v8::internal::Context> obj);
 206   static inline Local<Value> ToLocal(
 207       v8::internal::Handle<v8::internal::Object> obj);
 208   static inline Local<Function> ToLocal(
 209       v8::internal::Handle<v8::internal::JSFunction> obj);
 210   static inline Local<String> ToLocal(
 211       v8::internal::Handle<v8::internal::String> obj);
 212   static inline Local<Symbol> ToLocal(
 213       v8::internal::Handle<v8::internal::Symbol> obj);
 214   static inline Local<RegExp> ToLocal(
 215       v8::internal::Handle<v8::internal::JSRegExp> obj);
 216   static inline Local<Object> ToLocal(
 217       v8::internal::Handle<v8::internal::JSObject> obj);
 218   static inline Local<Array> ToLocal(
 219       v8::internal::Handle<v8::internal::JSArray> obj);
 220   static inline Local<ArrayBuffer> ToLocal(
 221       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 222   static inline Local<ArrayBufferView> ToLocal(
 223       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 224   static inline Local<DataView> ToLocal(
 225       v8::internal::Handle<v8::internal::JSDataView> obj);
 226
 227   static inline Local<TypedArray> ToLocal(
 228       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 229   static inline Local<Uint8Array> ToLocalUint8Array(
 230       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 231   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233   static inline Local<Int8Array> ToLocalInt8Array(
 234       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 235   static inline Local<Uint16Array> ToLocalUint16Array(
 236       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 237   static inline Local<Int16Array> ToLocalInt16Array(
 238       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 239   static inline Local<Uint32Array> ToLocalUint32Array(
 240       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 241   static inline Local<Int32Array> ToLocalInt32Array(
 242       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 243   static inline Local<Float32Array> ToLocalFloat32Array(
 244       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 245   static inline Local<Float64Array> ToLocalFloat64Array(
 246       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 247
 248   static inline Local<Message> MessageToLocal(
 249       v8::internal::Handle<v8::internal::Object> obj);
 250   static inline Local<StackTrace> StackTraceToLocal(
 251       v8::internal::Handle<v8::internal::JSArray> obj);
 252   static inline Local<StackFrame> StackFrameToLocal(
 253       v8::internal::Handle<v8::internal::JSObject> obj);
 254   static inline Local<Number> NumberToLocal(
 255       v8::internal::Handle<v8::internal::Object> obj);
 256   static inline Local<Integer> IntegerToLocal(
 257       v8::internal::Handle<v8::internal::Object> obj);
 258   static inline Local<Uint32> Uint32ToLocal(
 259       v8::internal::Handle<v8::internal::Object> obj);
 260   static inline Local<FunctionTemplate> ToLocal(
 261       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 262   static inline Local<ObjectTemplate> ToLocal(
 263       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 264   static inline Local<Signature> ToLocal(
 265       v8::internal::Handle<v8::internal::SignatureInfo> obj);
 266   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 267       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 268   static inline Local<TypeSwitch> ToLocal(
 269       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 270   static inline Local<External> ExternalToLocal(
 271       v8::internal::Handle<v8::internal::JSObject> obj);
 272   static inline Local<DeclaredAccessorDescriptor> ToLocal(
 273       v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);
 274
 275 #define DECLARE_OPEN_HANDLE(From, To) \
 276   static inline v8::internal::Handle<v8::internal::To> \
 277       OpenHandle(const From* that, bool allow_empty_handle = false);
 278
 279 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 280
 281 #undef DECLARE_OPEN_HANDLE
 282
 283   template<class From, class To>
 284   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 285     ASSERT(obj.is_null() || !obj->IsTheHole());
 286     return Local<To>(reinterpret_cast<To*>(obj.location()));
 287   }
 288
 289   template <class T>
 290   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 291       const v8::Persistent<T>& persistent) {
 292     return v8::internal::Handle<v8::internal::Object>(
 293         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 294   }
 295
 296   template <class T>
 297   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 298       v8::Persistent<T>* persistent) {
 299     return OpenPersistent(*persistent);
 300   }
 301
 302   template <class From, class To>
 303   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 304     return OpenHandle(*handle);
 305   }
 306 };
 307
 308
 309 template <class T>
 310 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 311     v8::HandleScope* scope) {
 312   v8::internal::Handle<T> handle;
 313   if (!is_null()) {
 314     handle = *this;
 315   }
 316   return Utils::OpenHandle(*scope->Close(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 // Implementations of ToLocal
 333
 334 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 335   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 336     return Convert<v8::internal::From, v8::To>(obj);  \
 337   }
 338
 339
 340 #define MAKE_TO_LOCAL_TYPED_ARRAY(TypedArray, typeConst)                    \
 341   Local<v8::TypedArray> Utils::ToLocal##TypedArray(                         \
 342       v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \
 343     ASSERT(obj->type() == typeConst);                                       \
 344     return Convert<v8::internal::JSTypedArray, v8::TypedArray>(obj);        \
 345   }
 346
 347
 348 MAKE_TO_LOCAL(ToLocal, Context, Context)
 349 MAKE_TO_LOCAL(ToLocal, Object, Value)
 350 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 351 MAKE_TO_LOCAL(ToLocal, String, String)
 352 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 353 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 354 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 355 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 356 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 357 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 358 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 359 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 360
 361 MAKE_TO_LOCAL_TYPED_ARRAY(Uint8Array, kExternalUnsignedByteArray)
 362 MAKE_TO_LOCAL_TYPED_ARRAY(Uint8ClampedArray, kExternalPixelArray)
 363 MAKE_TO_LOCAL_TYPED_ARRAY(Int8Array, kExternalByteArray)
 364 MAKE_TO_LOCAL_TYPED_ARRAY(Uint16Array, kExternalUnsignedShortArray)
 365 MAKE_TO_LOCAL_TYPED_ARRAY(Int16Array, kExternalShortArray)
 366 MAKE_TO_LOCAL_TYPED_ARRAY(Uint32Array, kExternalUnsignedIntArray)
 367 MAKE_TO_LOCAL_TYPED_ARRAY(Int32Array, kExternalIntArray)
 368 MAKE_TO_LOCAL_TYPED_ARRAY(Float32Array, kExternalFloatArray)
 369 MAKE_TO_LOCAL_TYPED_ARRAY(Float64Array, kExternalDoubleArray)
 370
 371 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 372 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 373 MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
 374 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 375 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 376 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 377 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 378 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 379 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 380 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 381 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 382 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 383 MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 384
 385 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 386 #undef MAKE_TO_LOCAL
 387
 388
 389 // Implementations of OpenHandle
 390
 391 #define MAKE_OPEN_HANDLE(From, To)                                          \
 392   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \
 393     const v8::From* that, bool allow_empty_handle) {                        \
 394     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
 395     EXTRA_CHECK(that == NULL ||                                             \
 396         !(*reinterpret_cast<v8::internal::To**>(                            \
 397             const_cast<v8::From*>(that)))->IsFailure());                    \
 398     return v8::internal::Handle<v8::internal::To>(                          \
 399         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
 400   }
 401
 402 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 403
 404 #undef MAKE_OPEN_HANDLE
 405 #undef OPEN_HANDLE_LIST
 406
 407
 408 namespace internal {
 409
 410 // Tracks string usage to help make better decisions when
 411 // externalizing strings.
 412 //
 413 // Implementation note: internally this class only tracks fresh
 414 // strings and keeps a single use counter for them.
 415 class StringTracker {
 416  public:
 417   // Records that the given string's characters were copied to some
 418   // external buffer. If this happens often we should honor
 419   // externalization requests for the string.
 420   void RecordWrite(Handle<String> string) {
 421     Address address = reinterpret_cast<Address>(*string);
 422     Address top = isolate_->heap()->NewSpaceTop();
 423     if (IsFreshString(address, top)) {
 424       IncrementUseCount(top);
 425     }
 426   }
 427
 428   // Estimates freshness and use frequency of the given string based
 429   // on how close it is to the new space top and the recorded usage
 430   // history.
 431   inline bool IsFreshUnusedString(Handle<String> string) {
 432     Address address = reinterpret_cast<Address>(*string);
 433     Address top = isolate_->heap()->NewSpaceTop();
 434     return IsFreshString(address, top) && IsUseCountLow(top);
 435   }
 436
 437  private:
 438   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 439
 440   static inline bool IsFreshString(Address string, Address top) {
 441     return top - kFreshnessLimit <= string && string <= top;
 442   }
 443
 444   inline bool IsUseCountLow(Address top) {
 445     if (last_top_ != top) return true;
 446     return use_count_ < kUseLimit;
 447   }
 448
 449   inline void IncrementUseCount(Address top) {
 450     if (last_top_ != top) {
 451       use_count_ = 0;
 452       last_top_ = top;
 453     }
 454     ++use_count_;
 455   }
 456
 457   // Single use counter shared by all fresh strings.
 458   int use_count_;
 459
 460   // Last new space top when the use count above was valid.
 461   Address last_top_;
 462
 463   Isolate* isolate_;
 464
 465   // How close to the new space top a fresh string has to be.
 466   static const int kFreshnessLimit = 1024;
 467
 468   // The number of uses required to consider a string useful.
 469   static const int kUseLimit = 32;
 470
 471   friend class Isolate;
 472
 473   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 474 };
 475
 476
 477 class DeferredHandles {
 478  public:
 479   ~DeferredHandles();
 480
 481  private:
 482   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 483       : next_(NULL),
 484         previous_(NULL),
 485         first_block_limit_(first_block_limit),
 486         isolate_(isolate) {
 487     isolate->LinkDeferredHandles(this);
 488   }
 489
 490   void Iterate(ObjectVisitor* v);
 491
 492   List<Object**> blocks_;
 493   DeferredHandles* next_;
 494   DeferredHandles* previous_;
 495   Object** first_block_limit_;
 496   Isolate* isolate_;
 497
 498   friend class HandleScopeImplementer;
 499   friend class Isolate;
 500 };
 501
 502
 503 // This class is here in order to be able to declare it a friend of
 504 // HandleScope.  Moving these methods to be members of HandleScope would be
 505 // neat in some ways, but it would expose internal implementation details in
 506 // our public header file, which is undesirable.
 507 //
 508 // An isolate has a single instance of this class to hold the current thread's
 509 // data. In multithreaded V8 programs this data is copied in and out of storage
 510 // so that the currently executing thread always has its own copy of this
 511 // data.
 512 class HandleScopeImplementer {
 513  public:
 514   explicit HandleScopeImplementer(Isolate* isolate)
 515       : isolate_(isolate),
 516         blocks_(0),
 517         entered_contexts_(0),
 518         saved_contexts_(0),
 519         spare_(NULL),
 520         call_depth_(0),
 521         last_handle_before_deferred_block_(NULL) { }
 522
 523   ~HandleScopeImplementer() {
 524     DeleteArray(spare_);
 525   }
 526
 527   // Threading support for handle data.
 528   static int ArchiveSpacePerThread();
 529   char* RestoreThread(char* from);
 530   char* ArchiveThread(char* to);
 531   void FreeThreadResources();
 532
 533   // Garbage collection support.
 534   void Iterate(v8::internal::ObjectVisitor* v);
 535   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 536
 537
 538   inline internal::Object** GetSpareOrNewBlock();
 539   inline void DeleteExtensions(internal::Object** prev_limit);
 540
 541   inline void IncrementCallDepth() {call_depth_++;}
 542   inline void DecrementCallDepth() {call_depth_--;}
 543   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 544
 545   inline void EnterContext(Handle<Object> context);
 546   inline bool LeaveContext(Handle<Object> context);
 547
 548   // Returns the last entered context or an empty handle if no
 549   // contexts have been entered.
 550   inline Handle<Object> LastEnteredContext();
 551
 552   inline void SaveContext(Context* context);
 553   inline Context* RestoreContext();
 554   inline bool HasSavedContexts();
 555
 556   inline List<internal::Object**>* blocks() { return &blocks_; }
 557   Isolate* isolate() const { return isolate_; }
 558
 559   void ReturnBlock(Object** block) {
 560     ASSERT(block != NULL);
 561     if (spare_ != NULL) DeleteArray(spare_);
 562     spare_ = block;
 563   }
 564
 565  private:
 566   void ResetAfterArchive() {
 567     blocks_.Initialize(0);
 568     entered_contexts_.Initialize(0);
 569     saved_contexts_.Initialize(0);
 570     spare_ = NULL;
 571     last_handle_before_deferred_block_ = NULL;
 572     call_depth_ = 0;
 573   }
 574
 575   void Free() {
 576     ASSERT(blocks_.length() == 0);
 577     ASSERT(entered_contexts_.length() == 0);
 578     ASSERT(saved_contexts_.length() == 0);
 579     blocks_.Free();
 580     entered_contexts_.Free();
 581     saved_contexts_.Free();
 582     if (spare_ != NULL) {
 583       DeleteArray(spare_);
 584       spare_ = NULL;
 585     }
 586     ASSERT(call_depth_ == 0);
 587   }
 588
 589   void BeginDeferredScope();
 590   DeferredHandles* Detach(Object** prev_limit);
 591
 592   Isolate* isolate_;
 593   List<internal::Object**> blocks_;
 594   // Used as a stack to keep track of entered contexts.
 595   List<Handle<Object> > entered_contexts_;
 596   // Used as a stack to keep track of saved contexts.
 597   List<Context*> saved_contexts_;
 598   Object** spare_;
 599   int call_depth_;
 600   Object** last_handle_before_deferred_block_;
 601   // This is only used for threading support.
 602   v8::ImplementationUtilities::HandleScopeData handle_scope_data_;
 603
 604   void IterateThis(ObjectVisitor* v);
 605   char* RestoreThreadHelper(char* from);
 606   char* ArchiveThreadHelper(char* to);
 607
 608   friend class DeferredHandles;
 609   friend class DeferredHandleScope;
 610
 611   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 612 };
 613
 614
 615 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 616
 617
 618 void HandleScopeImplementer::SaveContext(Context* context) {
 619   saved_contexts_.Add(context);
 620 }
 621
 622
 623 Context* HandleScopeImplementer::RestoreContext() {
 624   return saved_contexts_.RemoveLast();
 625 }
 626
 627
 628 bool HandleScopeImplementer::HasSavedContexts() {
 629   return !saved_contexts_.is_empty();
 630 }
 631
 632
 633 void HandleScopeImplementer::EnterContext(Handle<Object> context) {
 634   entered_contexts_.Add(context);
 635 }
 636
 637
 638 bool HandleScopeImplementer::LeaveContext(Handle<Object> context) {
 639   if (entered_contexts_.is_empty()) return false;
 640   // TODO(dcarney): figure out what's wrong here
 641   // if (*entered_contexts_.last() != *context) return false;
 642   entered_contexts_.RemoveLast();
 643   return true;
 644 }
 645
 646
 647 Handle<Object> HandleScopeImplementer::LastEnteredContext() {
 648   if (entered_contexts_.is_empty()) return Handle<Object>::null();
 649   return entered_contexts_.last();
 650 }
 651
 652
 653 // If there's a spare block, use it for growing the current scope.
 654 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 655   internal::Object** block = (spare_ != NULL) ?
 656       spare_ :
 657       NewArray<internal::Object*>(kHandleBlockSize);
 658   spare_ = NULL;
 659   return block;
 660 }
 661
 662
 663 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 664   while (!blocks_.is_empty()) {
 665     internal::Object** block_start = blocks_.last();
 666     internal::Object** block_limit = block_start + kHandleBlockSize;
 667 #ifdef DEBUG
 668     // SealHandleScope may make the prev_limit to point inside the block.
 669     if (block_start <= prev_limit && prev_limit <= block_limit) {
 670 #ifdef ENABLE_EXTRA_CHECKS
 671       internal::HandleScope::ZapRange(prev_limit, block_limit);
 672 #endif
 673       break;
 674     }
 675 #else
 676     if (prev_limit == block_limit) break;
 677 #endif
 678
 679     blocks_.RemoveLast();
 680 #ifdef ENABLE_EXTRA_CHECKS
 681     internal::HandleScope::ZapRange(block_start, block_limit);
 682 #endif
 683     if (spare_ != NULL) {
 684       DeleteArray(spare_);
 685     }
 686     spare_ = block_start;
 687   }
 688   ASSERT((blocks_.is_empty() && prev_limit == NULL) ||
 689          (!blocks_.is_empty() && prev_limit != NULL));
 690 }
 691
 692
 693 // Interceptor functions called from generated inline caches to notify
 694 // CPU profiler that external callbacks are invoked.
 695 void InvokeAccessorGetterCallback(
 696     v8::Local<v8::String> property,
 697     const v8::PropertyCallbackInfo<v8::Value>& info,
 698     v8::AccessorGetterCallback getter);
 699
 700 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 701                             v8::FunctionCallback callback);
 702
 703 class Testing {
 704  public:
 705   static v8::Testing::StressType stress_type() { return stress_type_; }
 706   static void set_stress_type(v8::Testing::StressType stress_type) {
 707     stress_type_ = stress_type;
 708   }
 709
 710  private:
 711   static v8::Testing::StressType stress_type_;
 712 };
 713
 714 } }  // namespace v8::internal
 715
 716 #endif  // V8_API_H_