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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);
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);
value()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 
NeanderObject(v8::internal::Handle<v8::internal::Object> obj)70 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
71     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
72 
73 
NeanderObject(v8::internal::Object * obj)74 NeanderObject::NeanderObject(v8::internal::Object* obj)
75     : value_(v8::internal::Handle<v8::internal::JSObject>(
76         v8::internal::JSObject::cast(obj))) { }
77 
78 
NeanderArray(v8::internal::Handle<v8::internal::Object> obj)79 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
80     : obj_(obj) { }
81 
82 
get(int offset)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 
set(int offset,v8::internal::Object * value)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 
ToCData(v8::internal::Object * obj)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>
FromCData(v8::internal::Isolate * isolate,T obj)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:
ApiFunction(v8::internal::Address addr)116   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
address()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();
extension()129   Extension* extension() { return extension_; }
next()130   RegisteredExtension* next() { return next_; }
first_extension()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:
ApiCheck(bool condition,const char * location,const char * message)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 
OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)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>
OpenPersistent(const v8::Persistent<T> & persistent)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>
OpenPersistent(v8::Persistent<T> * persistent)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>
OpenHandle(v8::Local<From> handle)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>
ToApi(v8::internal::Handle<v8::internal::Object> obj)312 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
313   return reinterpret_cast<T*>(obj.location());
314 }
315 
316 template <class T>
ToApiHandle(v8::internal::Handle<v8::internal::Object> obj)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>
ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,Local<T> * local)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 
MAKE_TO_LOCAL(ToLocal,Context,Context)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