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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() ||
    285            (obj->IsSmi() ||
    286             !obj->IsTheHole(i::HeapObject::cast(*obj)->GetIsolate())));
    287     return Local<To>(reinterpret_cast<To*>(obj.location()));
    288   }
    289 
    290   template <class T>
    291   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
    292       const v8::Persistent<T>& persistent) {
    293     return v8::internal::Handle<v8::internal::Object>(
    294         reinterpret_cast<v8::internal::Object**>(persistent.val_));
    295   }
    296 
    297   template <class T>
    298   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
    299       v8::Persistent<T>* persistent) {
    300     return OpenPersistent(*persistent);
    301   }
    302 
    303   template <class From, class To>
    304   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
    305     return OpenHandle(*handle);
    306   }
    307 
    308  private:
    309   static void ReportApiFailure(const char* location, const char* message);
    310 };
    311 
    312 
    313 template <class T>
    314 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
    315   return reinterpret_cast<T*>(obj.location());
    316 }
    317 
    318 template <class T>
    319 inline v8::Local<T> ToApiHandle(
    320     v8::internal::Handle<v8::internal::Object> obj) {
    321   return Utils::Convert<v8::internal::Object, T>(obj);
    322 }
    323 
    324 
    325 template <class T>
    326 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
    327                     Local<T>* local) {
    328   v8::internal::Handle<v8::internal::Object> handle;
    329   if (maybe.ToHandle(&handle)) {
    330     *local = Utils::Convert<v8::internal::Object, T>(handle);
    331     return true;
    332   }
    333   return false;
    334 }
    335 
    336 
    337 // Implementations of ToLocal
    338 
    339 #define MAKE_TO_LOCAL(Name, From, To)                                       \
    340   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
    341     return Convert<v8::internal::From, v8::To>(obj);  \
    342   }
    343 
    344 
    345 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
    346   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
    347       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
    348     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
    349     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
    350   }
    351 
    352 
    353 MAKE_TO_LOCAL(ToLocal, Context, Context)
    354 MAKE_TO_LOCAL(ToLocal, Object, Value)
    355 MAKE_TO_LOCAL(ToLocal, Name, Name)
    356 MAKE_TO_LOCAL(ToLocal, String, String)
    357 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
    358 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
    359 MAKE_TO_LOCAL(ToLocal, JSReceiver, Object)
    360 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
    361 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
    362 MAKE_TO_LOCAL(ToLocal, JSMap, Map)
    363 MAKE_TO_LOCAL(ToLocal, JSSet, Set)
    364 MAKE_TO_LOCAL(ToLocal, JSProxy, Proxy)
    365 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
    366 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
    367 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
    368 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
    369 MAKE_TO_LOCAL(ToLocalShared, JSArrayBuffer, SharedArrayBuffer)
    370 
    371 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
    372 
    373 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
    374 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
    375 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
    376 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
    377 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
    378 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
    379 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
    380 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
    381 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
    382 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
    383 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
    384 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
    385 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
    386 MAKE_TO_LOCAL(CallableToLocal, JSReceiver, Function)
    387 
    388 #undef MAKE_TO_LOCAL_TYPED_ARRAY
    389 #undef MAKE_TO_LOCAL
    390 
    391 
    392 // Implementations of OpenHandle
    393 
    394 #define MAKE_OPEN_HANDLE(From, To)                                             \
    395   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
    396       const v8::From* that, bool allow_empty_handle) {                         \
    397     DCHECK(allow_empty_handle || that != NULL);                                \
    398     DCHECK(that == NULL ||                                                     \
    399            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
    400     return v8::internal::Handle<v8::internal::To>(                             \
    401         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
    402   }
    403 
    404 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
    405 
    406 #undef MAKE_OPEN_HANDLE
    407 #undef OPEN_HANDLE_LIST
    408 
    409 
    410 namespace internal {
    411 
    412 
    413 class DeferredHandles {
    414  public:
    415   ~DeferredHandles();
    416 
    417  private:
    418   DeferredHandles(Object** first_block_limit, Isolate* isolate)
    419       : next_(NULL),
    420         previous_(NULL),
    421         first_block_limit_(first_block_limit),
    422         isolate_(isolate) {
    423     isolate->LinkDeferredHandles(this);
    424   }
    425 
    426   void Iterate(ObjectVisitor* v);
    427 
    428   List<Object**> blocks_;
    429   DeferredHandles* next_;
    430   DeferredHandles* previous_;
    431   Object** first_block_limit_;
    432   Isolate* isolate_;
    433 
    434   friend class HandleScopeImplementer;
    435   friend class Isolate;
    436 };
    437 
    438 
    439 // This class is here in order to be able to declare it a friend of
    440 // HandleScope.  Moving these methods to be members of HandleScope would be
    441 // neat in some ways, but it would expose internal implementation details in
    442 // our public header file, which is undesirable.
    443 //
    444 // An isolate has a single instance of this class to hold the current thread's
    445 // data. In multithreaded V8 programs this data is copied in and out of storage
    446 // so that the currently executing thread always has its own copy of this
    447 // data.
    448 class HandleScopeImplementer {
    449  public:
    450   explicit HandleScopeImplementer(Isolate* isolate)
    451       : isolate_(isolate),
    452         blocks_(0),
    453         entered_contexts_(0),
    454         saved_contexts_(0),
    455         spare_(NULL),
    456         call_depth_(0),
    457         microtasks_depth_(0),
    458         microtasks_suppressions_(0),
    459 #ifdef DEBUG
    460         debug_microtasks_depth_(0),
    461 #endif
    462         microtasks_policy_(v8::MicrotasksPolicy::kAuto),
    463         last_handle_before_deferred_block_(NULL) { }
    464 
    465   ~HandleScopeImplementer() {
    466     DeleteArray(spare_);
    467   }
    468 
    469   // Threading support for handle data.
    470   static int ArchiveSpacePerThread();
    471   char* RestoreThread(char* from);
    472   char* ArchiveThread(char* to);
    473   void FreeThreadResources();
    474 
    475   // Garbage collection support.
    476   void Iterate(v8::internal::ObjectVisitor* v);
    477   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
    478 
    479 
    480   inline internal::Object** GetSpareOrNewBlock();
    481   inline void DeleteExtensions(internal::Object** prev_limit);
    482 
    483   // Call depth represents nested v8 api calls.
    484   inline void IncrementCallDepth() {call_depth_++;}
    485   inline void DecrementCallDepth() {call_depth_--;}
    486   inline bool CallDepthIsZero() { return call_depth_ == 0; }
    487 
    488   // Microtasks scope depth represents nested scopes controlling microtasks
    489   // invocation, which happens when depth reaches zero.
    490   inline void IncrementMicrotasksScopeDepth() {microtasks_depth_++;}
    491   inline void DecrementMicrotasksScopeDepth() {microtasks_depth_--;}
    492   inline int GetMicrotasksScopeDepth() { return microtasks_depth_; }
    493 
    494   // Possibly nested microtasks suppression scopes prevent microtasks
    495   // from running.
    496   inline void IncrementMicrotasksSuppressions() {microtasks_suppressions_++;}
    497   inline void DecrementMicrotasksSuppressions() {microtasks_suppressions_--;}
    498   inline bool HasMicrotasksSuppressions() { return !!microtasks_suppressions_; }
    499 
    500 #ifdef DEBUG
    501   // In debug we check that calls not intended to invoke microtasks are
    502   // still correctly wrapped with microtask scopes.
    503   inline void IncrementDebugMicrotasksScopeDepth() {debug_microtasks_depth_++;}
    504   inline void DecrementDebugMicrotasksScopeDepth() {debug_microtasks_depth_--;}
    505   inline bool DebugMicrotasksScopeDepthIsZero() {
    506     return debug_microtasks_depth_ == 0;
    507   }
    508 #endif
    509 
    510   inline void set_microtasks_policy(v8::MicrotasksPolicy policy);
    511   inline v8::MicrotasksPolicy microtasks_policy() const;
    512 
    513   inline void EnterContext(Handle<Context> context);
    514   inline void LeaveContext();
    515   inline bool LastEnteredContextWas(Handle<Context> context);
    516 
    517   // Returns the last entered context or an empty handle if no
    518   // contexts have been entered.
    519   inline Handle<Context> LastEnteredContext();
    520 
    521   inline void SaveContext(Context* context);
    522   inline Context* RestoreContext();
    523   inline bool HasSavedContexts();
    524 
    525   inline List<internal::Object**>* blocks() { return &blocks_; }
    526   Isolate* isolate() const { return isolate_; }
    527 
    528   void ReturnBlock(Object** block) {
    529     DCHECK(block != NULL);
    530     if (spare_ != NULL) DeleteArray(spare_);
    531     spare_ = block;
    532   }
    533 
    534  private:
    535   void ResetAfterArchive() {
    536     blocks_.Initialize(0);
    537     entered_contexts_.Initialize(0);
    538     saved_contexts_.Initialize(0);
    539     spare_ = NULL;
    540     last_handle_before_deferred_block_ = NULL;
    541     call_depth_ = 0;
    542   }
    543 
    544   void Free() {
    545     DCHECK(blocks_.length() == 0);
    546     DCHECK(entered_contexts_.length() == 0);
    547     DCHECK(saved_contexts_.length() == 0);
    548     blocks_.Free();
    549     entered_contexts_.Free();
    550     saved_contexts_.Free();
    551     if (spare_ != NULL) {
    552       DeleteArray(spare_);
    553       spare_ = NULL;
    554     }
    555     DCHECK(call_depth_ == 0);
    556   }
    557 
    558   void BeginDeferredScope();
    559   DeferredHandles* Detach(Object** prev_limit);
    560 
    561   Isolate* isolate_;
    562   List<internal::Object**> blocks_;
    563   // Used as a stack to keep track of entered contexts.
    564   List<Context*> entered_contexts_;
    565   // Used as a stack to keep track of saved contexts.
    566   List<Context*> saved_contexts_;
    567   Object** spare_;
    568   int call_depth_;
    569   int microtasks_depth_;
    570   int microtasks_suppressions_;
    571 #ifdef DEBUG
    572   int debug_microtasks_depth_;
    573 #endif
    574   v8::MicrotasksPolicy microtasks_policy_;
    575   Object** last_handle_before_deferred_block_;
    576   // This is only used for threading support.
    577   HandleScopeData handle_scope_data_;
    578 
    579   void IterateThis(ObjectVisitor* v);
    580   char* RestoreThreadHelper(char* from);
    581   char* ArchiveThreadHelper(char* to);
    582 
    583   friend class DeferredHandles;
    584   friend class DeferredHandleScope;
    585 
    586   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
    587 };
    588 
    589 
    590 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
    591 
    592 
    593 void HandleScopeImplementer::set_microtasks_policy(
    594     v8::MicrotasksPolicy policy) {
    595   microtasks_policy_ = policy;
    596 }
    597 
    598 
    599 v8::MicrotasksPolicy HandleScopeImplementer::microtasks_policy() const {
    600   return microtasks_policy_;
    601 }
    602 
    603 
    604 void HandleScopeImplementer::SaveContext(Context* context) {
    605   saved_contexts_.Add(context);
    606 }
    607 
    608 
    609 Context* HandleScopeImplementer::RestoreContext() {
    610   return saved_contexts_.RemoveLast();
    611 }
    612 
    613 
    614 bool HandleScopeImplementer::HasSavedContexts() {
    615   return !saved_contexts_.is_empty();
    616 }
    617 
    618 
    619 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
    620   entered_contexts_.Add(*context);
    621 }
    622 
    623 
    624 void HandleScopeImplementer::LeaveContext() {
    625   entered_contexts_.RemoveLast();
    626 }
    627 
    628 
    629 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
    630   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
    631 }
    632 
    633 
    634 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
    635   if (entered_contexts_.is_empty()) return Handle<Context>::null();
    636   return Handle<Context>(entered_contexts_.last());
    637 }
    638 
    639 
    640 // If there's a spare block, use it for growing the current scope.
    641 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
    642   internal::Object** block = (spare_ != NULL) ?
    643       spare_ :
    644       NewArray<internal::Object*>(kHandleBlockSize);
    645   spare_ = NULL;
    646   return block;
    647 }
    648 
    649 
    650 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
    651   while (!blocks_.is_empty()) {
    652     internal::Object** block_start = blocks_.last();
    653     internal::Object** block_limit = block_start + kHandleBlockSize;
    654 
    655     // SealHandleScope may make the prev_limit to point inside the block.
    656     if (block_start <= prev_limit && prev_limit <= block_limit) {
    657 #ifdef ENABLE_HANDLE_ZAPPING
    658       internal::HandleScope::ZapRange(prev_limit, block_limit);
    659 #endif
    660       break;
    661     }
    662 
    663     blocks_.RemoveLast();
    664 #ifdef ENABLE_HANDLE_ZAPPING
    665     internal::HandleScope::ZapRange(block_start, block_limit);
    666 #endif
    667     if (spare_ != NULL) {
    668       DeleteArray(spare_);
    669     }
    670     spare_ = block_start;
    671   }
    672   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
    673          (!blocks_.is_empty() && prev_limit != NULL));
    674 }
    675 
    676 
    677 // Interceptor functions called from generated inline caches to notify
    678 // CPU profiler that external callbacks are invoked.
    679 void InvokeAccessorGetterCallback(
    680     v8::Local<v8::Name> property,
    681     const v8::PropertyCallbackInfo<v8::Value>& info,
    682     v8::AccessorNameGetterCallback getter);
    683 
    684 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
    685                             v8::FunctionCallback callback);
    686 
    687 class Testing {
    688  public:
    689   static v8::Testing::StressType stress_type() { return stress_type_; }
    690   static void set_stress_type(v8::Testing::StressType stress_type) {
    691     stress_type_ = stress_type;
    692   }
    693 
    694  private:
    695   static v8::Testing::StressType stress_type_;
    696 };
    697 
    698 }  // namespace internal
    699 }  // namespace v8
    700 
    701 #endif  // V8_API_H_
    702