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      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 "include/v8-testing.h"
      9 #include "src/contexts.h"
     10 #include "src/factory.h"
     11 #include "src/isolate.h"
     12 #include "src/list.h"
     13 #include "src/objects-inl.h"
     14 
     15 namespace v8 {
     16 
     17 // Constants used in the implementation of the API.  The most natural thing
     18 // would usually be to place these with the classes that use them, but
     19 // we want to keep them out of v8.h because it is an externally
     20 // visible file.
     21 class Consts {
     22  public:
     23   enum TemplateType {
     24     FUNCTION_TEMPLATE = 0,
     25     OBJECT_TEMPLATE = 1
     26   };
     27 };
     28 
     29 
     30 // Utilities for working with neander-objects, primitive
     31 // env-independent JSObjects used by the api.
     32 class NeanderObject {
     33  public:
     34   explicit NeanderObject(v8::internal::Isolate* isolate, int size);
     35   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
     36   explicit inline NeanderObject(v8::internal::Object* obj);
     37   inline v8::internal::Object* get(int index);
     38   inline void set(int index, v8::internal::Object* value);
     39   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
     40   int size();
     41  private:
     42   v8::internal::Handle<v8::internal::JSObject> value_;
     43 };
     44 
     45 
     46 // Utilities for working with neander-arrays, a simple extensible
     47 // array abstraction built on neander-objects.
     48 class NeanderArray {
     49  public:
     50   explicit NeanderArray(v8::internal::Isolate* isolate);
     51   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
     52   inline v8::internal::Handle<v8::internal::JSObject> value() {
     53     return obj_.value();
     54   }
     55 
     56   void add(internal::Isolate* isolate,
     57            v8::internal::Handle<v8::internal::Object> value);
     58 
     59   int length();
     60 
     61   v8::internal::Object* get(int index);
     62   // Change the value at an index to undefined value. If the index is
     63   // out of bounds, the request is ignored. Returns the old value.
     64   void set(int index, v8::internal::Object* value);
     65  private:
     66   NeanderObject obj_;
     67 };
     68 
     69 
     70 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
     71     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
     72 
     73 
     74 NeanderObject::NeanderObject(v8::internal::Object* obj)
     75     : value_(v8::internal::Handle<v8::internal::JSObject>(
     76         v8::internal::JSObject::cast(obj))) { }
     77 
     78 
     79 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
     80     : obj_(obj) { }
     81 
     82 
     83 v8::internal::Object* NeanderObject::get(int offset) {
     84   DCHECK(value()->HasFastObjectElements());
     85   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
     86 }
     87 
     88 
     89 void NeanderObject::set(int offset, v8::internal::Object* value) {
     90   DCHECK(value_->HasFastObjectElements());
     91   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
     92 }
     93 
     94 
     95 template <typename T> inline T ToCData(v8::internal::Object* obj) {
     96   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
     97   if (obj == v8::internal::Smi::FromInt(0)) return nullptr;
     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   if (obj == nullptr) return handle(v8::internal::Smi::FromInt(0), isolate);
    109   return isolate->factory()->NewForeign(
    110       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
    111 }
    112 
    113 
    114 class ApiFunction {
    115  public:
    116   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
    117   v8::internal::Address address() { return addr_; }
    118  private:
    119   v8::internal::Address addr_;
    120 };
    121 
    122 
    123 
    124 class RegisteredExtension {
    125  public:
    126   explicit RegisteredExtension(Extension* extension);
    127   static void Register(RegisteredExtension* that);
    128   static void UnregisterAll();
    129   Extension* extension() { return extension_; }
    130   RegisteredExtension* next() { return next_; }
    131   static RegisteredExtension* first_extension() { return first_extension_; }
    132  private:
    133   Extension* extension_;
    134   RegisteredExtension* next_;
    135   static RegisteredExtension* first_extension_;
    136 };
    137 
    138 
    139 #define OPEN_HANDLE_LIST(V)                  \
    140   V(Template, TemplateInfo)                  \
    141   V(FunctionTemplate, FunctionTemplateInfo)  \
    142   V(ObjectTemplate, ObjectTemplateInfo)      \
    143   V(Signature, FunctionTemplateInfo)         \
    144   V(AccessorSignature, FunctionTemplateInfo) \
    145   V(Data, Object)                            \
    146   V(RegExp, JSRegExp)                        \
    147   V(Object, JSReceiver)                      \
    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, JSReceiver)                    \
    171   V(Message, JSMessageObject)                \
    172   V(Context, Context)                        \
    173   V(External, Object)                        \
    174   V(StackTrace, JSArray)                     \
    175   V(StackFrame, JSObject)                    \
    176   V(Proxy, JSProxy)                          \
    177   V(NativeWeakMap, JSWeakMap)
    178 
    179 class Utils {
    180  public:
    181   static inline bool ApiCheck(bool condition,
    182                               const char* location,
    183                               const char* message) {
    184     if (!condition) Utils::ReportApiFailure(location, message);
    185     return condition;
    186   }
    187 
    188   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
    189   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
    190 
    191   static inline Local<Context> ToLocal(
    192       v8::internal::Handle<v8::internal::Context> obj);
    193   static inline Local<Value> ToLocal(
    194       v8::internal::Handle<v8::internal::Object> obj);
    195   static inline Local<Name> ToLocal(
    196       v8::internal::Handle<v8::internal::Name> obj);
    197   static inline Local<String> ToLocal(
    198       v8::internal::Handle<v8::internal::String> obj);
    199   static inline Local<Symbol> ToLocal(
    200       v8::internal::Handle<v8::internal::Symbol> obj);
    201   static inline Local<RegExp> ToLocal(
    202       v8::internal::Handle<v8::internal::JSRegExp> obj);
    203   static inline Local<Object> ToLocal(
    204       v8::internal::Handle<v8::internal::JSReceiver> obj);
    205   static inline Local<Object> ToLocal(
    206       v8::internal::Handle<v8::internal::JSObject> obj);
    207   static inline Local<Array> ToLocal(
    208       v8::internal::Handle<v8::internal::JSArray> obj);
    209   static inline Local<Map> ToLocal(
    210       v8::internal::Handle<v8::internal::JSMap> obj);
    211   static inline Local<Set> ToLocal(
    212       v8::internal::Handle<v8::internal::JSSet> obj);
    213   static inline Local<Proxy> ToLocal(
    214       v8::internal::Handle<v8::internal::JSProxy> obj);
    215   static inline Local<ArrayBuffer> ToLocal(
    216       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
    217   static inline Local<ArrayBufferView> ToLocal(
    218       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
    219   static inline Local<DataView> ToLocal(
    220       v8::internal::Handle<v8::internal::JSDataView> obj);
    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<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   static inline Local<Function> CallableToLocal(
    272       v8::internal::Handle<v8::internal::JSReceiver> 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 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
    313   return reinterpret_cast<T*>(obj.location());
    314 }
    315 
    316 template <class T>
    317 inline v8::Local<T> ToApiHandle(
    318     v8::internal::Handle<v8::internal::Object> obj) {
    319   return Utils::Convert<v8::internal::Object, T>(obj);
    320 }
    321 
    322 
    323 template <class T>
    324 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
    325                     Local<T>* local) {
    326   v8::internal::Handle<v8::internal::Object> handle;
    327   if (maybe.ToHandle(&handle)) {
    328     *local = Utils::Convert<v8::internal::Object, T>(handle);
    329     return true;
    330   }
    331   return false;
    332 }
    333 
    334 
    335 // Implementations of ToLocal
    336 
    337 #define MAKE_TO_LOCAL(Name, From, To)                                       \
    338   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
    339     return Convert<v8::internal::From, v8::To>(obj);  \
    340   }
    341 
    342 
    343 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
    344   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
    345       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
    346     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
    347     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
    348   }
    349 
    350 
    351 MAKE_TO_LOCAL(ToLocal, Context, Context)
    352 MAKE_TO_LOCAL(ToLocal, Object, Value)
    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, JSReceiver, Object)
    358 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
    359 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
    360 MAKE_TO_LOCAL(ToLocal, JSMap, Map)
    361 MAKE_TO_LOCAL(ToLocal, JSSet, Set)
    362 MAKE_TO_LOCAL(ToLocal, JSProxy, Proxy)
    363 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
    364 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
    365 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
    366 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
    367 MAKE_TO_LOCAL(ToLocalShared, JSArrayBuffer, SharedArrayBuffer)
    368 
    369 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
    370 
    371 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
    372 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
    373 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
    374 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
    375 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
    376 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
    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(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
    384 MAKE_TO_LOCAL(CallableToLocal, JSReceiver, Function)
    385 
    386 #undef MAKE_TO_LOCAL_TYPED_ARRAY
    387 #undef MAKE_TO_LOCAL
    388 
    389 
    390 // Implementations of OpenHandle
    391 
    392 #define MAKE_OPEN_HANDLE(From, To)                                             \
    393   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
    394       const v8::From* that, bool allow_empty_handle) {                         \
    395     DCHECK(allow_empty_handle || that != NULL);                                \
    396     DCHECK(that == NULL ||                                                     \
    397            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
    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 
    411 class DeferredHandles {
    412  public:
    413   ~DeferredHandles();
    414 
    415  private:
    416   DeferredHandles(Object** first_block_limit, Isolate* isolate)
    417       : next_(NULL),
    418         previous_(NULL),
    419         first_block_limit_(first_block_limit),
    420         isolate_(isolate) {
    421     isolate->LinkDeferredHandles(this);
    422   }
    423 
    424   void Iterate(ObjectVisitor* v);
    425 
    426   List<Object**> blocks_;
    427   DeferredHandles* next_;
    428   DeferredHandles* previous_;
    429   Object** first_block_limit_;
    430   Isolate* isolate_;
    431 
    432   friend class HandleScopeImplementer;
    433   friend class Isolate;
    434 };
    435 
    436 
    437 // This class is here in order to be able to declare it a friend of
    438 // HandleScope.  Moving these methods to be members of HandleScope would be
    439 // neat in some ways, but it would expose internal implementation details in
    440 // our public header file, which is undesirable.
    441 //
    442 // An isolate has a single instance of this class to hold the current thread's
    443 // data. In multithreaded V8 programs this data is copied in and out of storage
    444 // so that the currently executing thread always has its own copy of this
    445 // data.
    446 class HandleScopeImplementer {
    447  public:
    448   explicit HandleScopeImplementer(Isolate* isolate)
    449       : isolate_(isolate),
    450         blocks_(0),
    451         entered_contexts_(0),
    452         saved_contexts_(0),
    453         spare_(NULL),
    454         call_depth_(0),
    455         last_handle_before_deferred_block_(NULL) { }
    456 
    457   ~HandleScopeImplementer() {
    458     DeleteArray(spare_);
    459   }
    460 
    461   // Threading support for handle data.
    462   static int ArchiveSpacePerThread();
    463   char* RestoreThread(char* from);
    464   char* ArchiveThread(char* to);
    465   void FreeThreadResources();
    466 
    467   // Garbage collection support.
    468   void Iterate(v8::internal::ObjectVisitor* v);
    469   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
    470 
    471 
    472   inline internal::Object** GetSpareOrNewBlock();
    473   inline void DeleteExtensions(internal::Object** prev_limit);
    474 
    475   inline void IncrementCallDepth() {call_depth_++;}
    476   inline void DecrementCallDepth() {call_depth_--;}
    477   inline bool CallDepthIsZero() { return call_depth_ == 0; }
    478 
    479   inline void EnterContext(Handle<Context> context);
    480   inline void LeaveContext();
    481   inline bool LastEnteredContextWas(Handle<Context> context);
    482 
    483   // Returns the last entered context or an empty handle if no
    484   // contexts have been entered.
    485   inline Handle<Context> LastEnteredContext();
    486 
    487   inline void SaveContext(Context* context);
    488   inline Context* RestoreContext();
    489   inline bool HasSavedContexts();
    490 
    491   inline List<internal::Object**>* blocks() { return &blocks_; }
    492   Isolate* isolate() const { return isolate_; }
    493 
    494   void ReturnBlock(Object** block) {
    495     DCHECK(block != NULL);
    496     if (spare_ != NULL) DeleteArray(spare_);
    497     spare_ = block;
    498   }
    499 
    500  private:
    501   void ResetAfterArchive() {
    502     blocks_.Initialize(0);
    503     entered_contexts_.Initialize(0);
    504     saved_contexts_.Initialize(0);
    505     spare_ = NULL;
    506     last_handle_before_deferred_block_ = NULL;
    507     call_depth_ = 0;
    508   }
    509 
    510   void Free() {
    511     DCHECK(blocks_.length() == 0);
    512     DCHECK(entered_contexts_.length() == 0);
    513     DCHECK(saved_contexts_.length() == 0);
    514     blocks_.Free();
    515     entered_contexts_.Free();
    516     saved_contexts_.Free();
    517     if (spare_ != NULL) {
    518       DeleteArray(spare_);
    519       spare_ = NULL;
    520     }
    521     DCHECK(call_depth_ == 0);
    522   }
    523 
    524   void BeginDeferredScope();
    525   DeferredHandles* Detach(Object** prev_limit);
    526 
    527   Isolate* isolate_;
    528   List<internal::Object**> blocks_;
    529   // Used as a stack to keep track of entered contexts.
    530   List<Context*> entered_contexts_;
    531   // Used as a stack to keep track of saved contexts.
    532   List<Context*> saved_contexts_;
    533   Object** spare_;
    534   int call_depth_;
    535   Object** last_handle_before_deferred_block_;
    536   // This is only used for threading support.
    537   HandleScopeData handle_scope_data_;
    538 
    539   void IterateThis(ObjectVisitor* v);
    540   char* RestoreThreadHelper(char* from);
    541   char* ArchiveThreadHelper(char* to);
    542 
    543   friend class DeferredHandles;
    544   friend class DeferredHandleScope;
    545 
    546   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
    547 };
    548 
    549 
    550 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
    551 
    552 
    553 void HandleScopeImplementer::SaveContext(Context* context) {
    554   saved_contexts_.Add(context);
    555 }
    556 
    557 
    558 Context* HandleScopeImplementer::RestoreContext() {
    559   return saved_contexts_.RemoveLast();
    560 }
    561 
    562 
    563 bool HandleScopeImplementer::HasSavedContexts() {
    564   return !saved_contexts_.is_empty();
    565 }
    566 
    567 
    568 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
    569   entered_contexts_.Add(*context);
    570 }
    571 
    572 
    573 void HandleScopeImplementer::LeaveContext() {
    574   entered_contexts_.RemoveLast();
    575 }
    576 
    577 
    578 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
    579   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
    580 }
    581 
    582 
    583 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
    584   if (entered_contexts_.is_empty()) return Handle<Context>::null();
    585   return Handle<Context>(entered_contexts_.last());
    586 }
    587 
    588 
    589 // If there's a spare block, use it for growing the current scope.
    590 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
    591   internal::Object** block = (spare_ != NULL) ?
    592       spare_ :
    593       NewArray<internal::Object*>(kHandleBlockSize);
    594   spare_ = NULL;
    595   return block;
    596 }
    597 
    598 
    599 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
    600   while (!blocks_.is_empty()) {
    601     internal::Object** block_start = blocks_.last();
    602     internal::Object** block_limit = block_start + kHandleBlockSize;
    603 
    604     // SealHandleScope may make the prev_limit to point inside the block.
    605     if (block_start <= prev_limit && prev_limit <= block_limit) {
    606 #ifdef ENABLE_HANDLE_ZAPPING
    607       internal::HandleScope::ZapRange(prev_limit, block_limit);
    608 #endif
    609       break;
    610     }
    611 
    612     blocks_.RemoveLast();
    613 #ifdef ENABLE_HANDLE_ZAPPING
    614     internal::HandleScope::ZapRange(block_start, block_limit);
    615 #endif
    616     if (spare_ != NULL) {
    617       DeleteArray(spare_);
    618     }
    619     spare_ = block_start;
    620   }
    621   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
    622          (!blocks_.is_empty() && prev_limit != NULL));
    623 }
    624 
    625 
    626 // Interceptor functions called from generated inline caches to notify
    627 // CPU profiler that external callbacks are invoked.
    628 void InvokeAccessorGetterCallback(
    629     v8::Local<v8::Name> property,
    630     const v8::PropertyCallbackInfo<v8::Value>& info,
    631     v8::AccessorNameGetterCallback getter);
    632 
    633 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
    634                             v8::FunctionCallback callback);
    635 
    636 class Testing {
    637  public:
    638   static v8::Testing::StressType stress_type() { return stress_type_; }
    639   static void set_stress_type(v8::Testing::StressType stress_type) {
    640     stress_type_ = stress_type;
    641   }
    642 
    643  private:
    644   static v8::Testing::StressType stress_type_;
    645 };
    646 
    647 }  // namespace internal
    648 }  // namespace v8
    649 
    650 #endif  // V8_API_H_
    651