CSE2410 Fall 2014 Bounce

// Copyright 2012 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_API_H_

#define V8_API_H_

#include "v8.h"

#include "../include/v8-testing.h"

#include "apiutils.h"

#include "contexts.h"

#include "factory.h"

#include "isolate.h"

#include "list-inl.h"

namespace v8 {

// Constants used in the implementation of the API.  The most natural thing

// would usually be to place these with the classes that use them, but

// we want to keep them out of v8.h because it is an externally

// visible file.

class Consts {

 public:

  enum TemplateType {

    FUNCTION_TEMPLATE = 0,

    OBJECT_TEMPLATE = 1

  };

};

// Utilities for working with neander-objects, primitive

// env-independent JSObjects used by the api.

class NeanderObject {

 public:

  explicit NeanderObject(int size);

  explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);

  explicit inline NeanderObject(v8::internal::Object* obj);

  inline v8::internal::Object* get(int index);

  inline void set(int index, v8::internal::Object* value);

  inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }

  int size();

 private:

  v8::internal::Handle<v8::internal::JSObject> value_;

};

// Utilities for working with neander-arrays, a simple extensible

// array abstraction built on neander-objects.

class NeanderArray {

 public:

  NeanderArray();

  explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);

  inline v8::internal::Handle<v8::internal::JSObject> value() {

    return obj_.value();

  }

  void add(v8::internal::Handle<v8::internal::Object> value);

  int length();

  v8::internal::Object* get(int index);

  // Change the value at an index to undefined value. If the index is

  // out of bounds, the request is ignored. Returns the old value.

  void set(int index, v8::internal::Object* value);

 private:

  NeanderObject obj_;

};

NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)

    : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }

NeanderObject::NeanderObject(v8::internal::Object* obj)

    : value_(v8::internal::Handle<v8::internal::JSObject>(

        v8::internal::JSObject::cast(obj))) { }

NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)

    : obj_(obj) { }

v8::internal::Object* NeanderObject::get(int offset) {

  ASSERT(value()->HasFastObjectElements());

  return v8::internal::FixedArray::cast(value()->elements())->get(offset);

}

void NeanderObject::set(int offset, v8::internal::Object* value) {

  ASSERT(value_->HasFastObjectElements());

  v8::internal::FixedArray::cast(value_->elements())->set(offset, value);

}

template <typename T> inline T ToCData(v8::internal::Object* obj) {

  STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));

  return reinterpret_cast<T>(

      reinterpret_cast<intptr_t>(

          v8::internal::Foreign::cast(obj)->foreign_address()));

}

template <typename T>

inline v8::internal::Handle<v8::internal::Object> FromCData(

    v8::internal::Isolate* isolate, T obj) {

  STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));

  return isolate->factory()->NewForeign(

      reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));

}

class ApiFunction {

 public:

  explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }

  v8::internal::Address address() { return addr_; }

 private:

  v8::internal::Address addr_;

};

class RegisteredExtension {

 public:

  explicit RegisteredExtension(Extension* extension);

  static void Register(RegisteredExtension* that);

  static void UnregisterAll();

  Extension* extension() { return extension_; }

  RegisteredExtension* next() { return next_; }

  static RegisteredExtension* first_extension() { return first_extension_; }

 private:

  Extension* extension_;

  RegisteredExtension* next_;

  static RegisteredExtension* first_extension_;

};

#define OPEN_HANDLE_LIST(V)                    \

  V(Template, TemplateInfo)                    \

  V(FunctionTemplate, FunctionTemplateInfo)    \

  V(ObjectTemplate, ObjectTemplateInfo)        \

  V(Signature, SignatureInfo)                  \

  V(AccessorSignature, FunctionTemplateInfo)   \

  V(TypeSwitch, TypeSwitchInfo)                \

  V(Data, Object)                              \

  V(RegExp, JSRegExp)                          \

  V(Object, JSObject)                          \

  V(Array, JSArray)                            \

  V(ArrayBuffer, JSArrayBuffer)                \

  V(ArrayBufferView, JSArrayBufferView)        \

  V(TypedArray, JSTypedArray)                  \

  V(Uint8Array, JSTypedArray)                  \

  V(Uint8ClampedArray, JSTypedArray)           \

  V(Int8Array, JSTypedArray)                   \

  V(Uint16Array, JSTypedArray)                 \

  V(Int16Array, JSTypedArray)                  \

  V(Uint32Array, JSTypedArray)                 \

  V(Int32Array, JSTypedArray)                  \

  V(Float32Array, JSTypedArray)                \

  V(Float64Array, JSTypedArray)                \

  V(DataView, JSDataView)                      \

  V(String, String)                            \

  V(Symbol, Symbol)                            \

  V(Script, Object)                            \

  V(Function, JSFunction)                      \

  V(Message, JSObject)                         \

  V(Context, Context)                          \

  V(External, Foreign)                         \

  V(StackTrace, JSArray)                       \

  V(StackFrame, JSObject)                      \

  V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)

class Utils {

 public:

  static bool ReportApiFailure(const char* location, const char* message);

  static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);

  static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);

  static inline Local<Context> ToLocal(

      v8::internal::Handle<v8::internal::Context> obj);

  static inline Local<Value> ToLocal(

      v8::internal::Handle<v8::internal::Object> obj);

  static inline Local<Function> ToLocal(

      v8::internal::Handle<v8::internal::JSFunction> obj);

  static inline Local<String> ToLocal(

      v8::internal::Handle<v8::internal::String> obj);

  static inline Local<Symbol> ToLocal(

      v8::internal::Handle<v8::internal::Symbol> obj);

  static inline Local<RegExp> ToLocal(

      v8::internal::Handle<v8::internal::JSRegExp> obj);

  static inline Local<Object> ToLocal(

      v8::internal::Handle<v8::internal::JSObject> obj);

  static inline Local<Array> ToLocal(

      v8::internal::Handle<v8::internal::JSArray> obj);

  static inline Local<ArrayBuffer> ToLocal(

      v8::internal::Handle<v8::internal::JSArrayBuffer> obj);

  static inline Local<ArrayBufferView> ToLocal(

      v8::internal::Handle<v8::internal::JSArrayBufferView> obj);

  static inline Local<DataView> ToLocal(

      v8::internal::Handle<v8::internal::JSDataView> obj);

  static inline Local<TypedArray> ToLocal(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Uint8Array> ToLocalUint8Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Int8Array> ToLocalInt8Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Uint16Array> ToLocalUint16Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Int16Array> ToLocalInt16Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Uint32Array> ToLocalUint32Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Int32Array> ToLocalInt32Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Float32Array> ToLocalFloat32Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Float64Array> ToLocalFloat64Array(

      v8::internal::Handle<v8::internal::JSTypedArray> obj);

  static inline Local<Message> MessageToLocal(

      v8::internal::Handle<v8::internal::Object> obj);

  static inline Local<StackTrace> StackTraceToLocal(

      v8::internal::Handle<v8::internal::JSArray> obj);

  static inline Local<StackFrame> StackFrameToLocal(

      v8::internal::Handle<v8::internal::JSObject> obj);

  static inline Local<Number> NumberToLocal(

      v8::internal::Handle<v8::internal::Object> obj);

  static inline Local<Integer> IntegerToLocal(

      v8::internal::Handle<v8::internal::Object> obj);

  static inline Local<Uint32> Uint32ToLocal(

      v8::internal::Handle<v8::internal::Object> obj);

  static inline Local<FunctionTemplate> ToLocal(

      v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);

  static inline Local<ObjectTemplate> ToLocal(

      v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);

  static inline Local<Signature> ToLocal(

      v8::internal::Handle<v8::internal::SignatureInfo> obj);

  static inline Local<AccessorSignature> AccessorSignatureToLocal(

      v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);

  static inline Local<TypeSwitch> ToLocal(

      v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);

  static inline Local<External> ExternalToLocal(

      v8::internal::Handle<v8::internal::JSObject> obj);

  static inline Local<DeclaredAccessorDescriptor> ToLocal(

      v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);

#define DECLARE_OPEN_HANDLE(From, To) \

  static inline v8::internal::Handle<v8::internal::To> \

      OpenHandle(const From* that, bool allow_empty_handle = false);

OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)

#undef DECLARE_OPEN_HANDLE

  template<class From, class To>

  static inline Local<To> Convert(v8::internal::Handle<From> obj) {

    ASSERT(obj.is_null() || !obj->IsTheHole());

    return Local<To>(reinterpret_cast<To*>(obj.location()));

  }

  template <class T>

  static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(

      const v8::Persistent<T>& persistent) {

    return v8::internal::Handle<v8::internal::Object>(

        reinterpret_cast<v8::internal::Object**>(persistent.val_));

  }

  template <class T>

  static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(

      v8::Persistent<T>* persistent) {

    return OpenPersistent(*persistent);

  }

  template <class From, class To>

  static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {

    return OpenHandle(*handle);

  }

};

template <class T>

v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(

    v8::HandleScope* scope) {

  v8::internal::Handle<T> handle;

  if (!is_null()) {

    handle = *this;

  }

  return Utils::OpenHandle(*scope->Close(Utils::ToLocal(handle)), true);

}

template <class T>

inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {

  return reinterpret_cast<T*>(obj.location());

}

template <class T>

inline v8::Local<T> ToApiHandle(

    v8::internal::Handle<v8::internal::Object> obj) {

  return Utils::Convert<v8::internal::Object, T>(obj);

}

// Implementations of ToLocal

#define MAKE_TO_LOCAL(Name, From, To)                                       \

  Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \

    return Convert<v8::internal::From, v8::To>(obj);  \

  }

#define MAKE_TO_LOCAL_TYPED_ARRAY(TypedArray, typeConst)                    \

  Local<v8::TypedArray> Utils::ToLocal##TypedArray(                         \

      v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \

    ASSERT(obj->type() == typeConst);                                       \

    return Convert<v8::internal::JSTypedArray, v8::TypedArray>(obj);        \

  }

MAKE_TO_LOCAL(ToLocal, Context, Context)

MAKE_TO_LOCAL(ToLocal, Object, Value)

MAKE_TO_LOCAL(ToLocal, JSFunction, Function)

MAKE_TO_LOCAL(ToLocal, String, String)

MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)

MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)

MAKE_TO_LOCAL(ToLocal, JSObject, Object)

MAKE_TO_LOCAL(ToLocal, JSArray, Array)

MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)

MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)

MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)

MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Uint8Array, kExternalUnsignedByteArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Uint8ClampedArray, kExternalPixelArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Int8Array, kExternalByteArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Uint16Array, kExternalUnsignedShortArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Int16Array, kExternalShortArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Uint32Array, kExternalUnsignedIntArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Int32Array, kExternalIntArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Float32Array, kExternalFloatArray)

MAKE_TO_LOCAL_TYPED_ARRAY(Float64Array, kExternalDoubleArray)

MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)

MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)

MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)

MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)

MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)

MAKE_TO_LOCAL(MessageToLocal, Object, Message)

MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)

MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)

MAKE_TO_LOCAL(NumberToLocal, Object, Number)

MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)

MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)

MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)

MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)

#undef MAKE_TO_LOCAL_TYPED_ARRAY

#undef MAKE_TO_LOCAL

// Implementations of OpenHandle

#define MAKE_OPEN_HANDLE(From, To)                                          \

  v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \

    const v8::From* that, bool allow_empty_handle) {                        \

    EXTRA_CHECK(allow_empty_handle || that != NULL);                        \

    EXTRA_CHECK(that == NULL ||                                             \

        !(*reinterpret_cast<v8::internal::To**>(                            \

            const_cast<v8::From*>(that)))->IsFailure());                    \

    return v8::internal::Handle<v8::internal::To>(                          \

        reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \

  }

OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)

#undef MAKE_OPEN_HANDLE

#undef OPEN_HANDLE_LIST

namespace internal {

// Tracks string usage to help make better decisions when

// externalizing strings.

//

// Implementation note: internally this class only tracks fresh

// strings and keeps a single use counter for them.

class StringTracker {

 public:

  // Records that the given string's characters were copied to some

  // external buffer. If this happens often we should honor

  // externalization requests for the string.

  void RecordWrite(Handle<String> string) {

    Address address = reinterpret_cast<Address>(*string);

    Address top = isolate_->heap()->NewSpaceTop();

    if (IsFreshString(address, top)) {

      IncrementUseCount(top);

    }

  }

  // Estimates freshness and use frequency of the given string based

  // on how close it is to the new space top and the recorded usage

  // history.

  inline bool IsFreshUnusedString(Handle<String> string) {

    Address address = reinterpret_cast<Address>(*string);

    Address top = isolate_->heap()->NewSpaceTop();

    return IsFreshString(address, top) && IsUseCountLow(top);

  }

 private:

  StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }

  static inline bool IsFreshString(Address string, Address top) {

    return top - kFreshnessLimit <= string && string <= top;

  }

  inline bool IsUseCountLow(Address top) {

    if (last_top_ != top) return true;

    return use_count_ < kUseLimit;

  }

  inline void IncrementUseCount(Address top) {

    if (last_top_ != top) {

      use_count_ = 0;

      last_top_ = top;

    }

    ++use_count_;

  }

  // Single use counter shared by all fresh strings.

  int use_count_;

  // Last new space top when the use count above was valid.

  Address last_top_;

  Isolate* isolate_;

  // How close to the new space top a fresh string has to be.

  static const int kFreshnessLimit = 1024;

  // The number of uses required to consider a string useful.

  static const int kUseLimit = 32;

  friend class Isolate;

  DISALLOW_COPY_AND_ASSIGN(StringTracker);

};

class DeferredHandles {

 public:

  ~DeferredHandles();

 private:

  DeferredHandles(Object** first_block_limit, Isolate* isolate)

      : next_(NULL),

        previous_(NULL),

        first_block_limit_(first_block_limit),

        isolate_(isolate) {

    isolate->LinkDeferredHandles(this);

  }

  void Iterate(ObjectVisitor* v);

  List<Object**> blocks_;

  DeferredHandles* next_;

  DeferredHandles* previous_;

  Object** first_block_limit_;

  Isolate* isolate_;

  friend class HandleScopeImplementer;

  friend class Isolate;

};

// This class is here in order to be able to declare it a friend of

// HandleScope.  Moving these methods to be members of HandleScope would be

// neat in some ways, but it would expose internal implementation details in

// our public header file, which is undesirable.

//

// An isolate has a single instance of this class to hold the current thread's

// data. In multithreaded V8 programs this data is copied in and out of storage

// so that the currently executing thread always has its own copy of this

// data.

class HandleScopeImplementer {

 public:

  explicit HandleScopeImplementer(Isolate* isolate)

      : isolate_(isolate),

        blocks_(0),

        entered_contexts_(0),

        saved_contexts_(0),

        spare_(NULL),

        call_depth_(0),

        last_handle_before_deferred_block_(NULL) { }

  ~HandleScopeImplementer() {

    DeleteArray(spare_);

  }

  // Threading support for handle data.

  static int ArchiveSpacePerThread();

  char* RestoreThread(char* from);

  char* ArchiveThread(char* to);

  void FreeThreadResources();

  // Garbage collection support.

  void Iterate(v8::internal::ObjectVisitor* v);

  static char* Iterate(v8::internal::ObjectVisitor* v, char* data);

  inline internal::Object** GetSpareOrNewBlock();

  inline void DeleteExtensions(internal::Object** prev_limit);

  inline void IncrementCallDepth() {call_depth_++;}

  inline void DecrementCallDepth() {call_depth_--;}

  inline bool CallDepthIsZero() { return call_depth_ == 0; }

  inline void EnterContext(Handle<Context> context);

  inline bool LeaveContext(Handle<Context> context);

  // Returns the last entered context or an empty handle if no

  // contexts have been entered.

  inline Handle<Context> LastEnteredContext();

  inline void SaveContext(Context* context);

  inline Context* RestoreContext();

  inline bool HasSavedContexts();

  inline List<internal::Object**>* blocks() { return &blocks_; }

  Isolate* isolate() const { return isolate_; }

  void ReturnBlock(Object** block) {

    ASSERT(block != NULL);

    if (spare_ != NULL) DeleteArray(spare_);

    spare_ = block;

  }

 private:

  void ResetAfterArchive() {

    blocks_.Initialize(0);

    entered_contexts_.Initialize(0);

    saved_contexts_.Initialize(0);

    spare_ = NULL;

    last_handle_before_deferred_block_ = NULL;

    call_depth_ = 0;

  }

  void Free() {

    ASSERT(blocks_.length() == 0);

    ASSERT(entered_contexts_.length() == 0);

    ASSERT(saved_contexts_.length() == 0);

    blocks_.Free();

    entered_contexts_.Free();

    saved_contexts_.Free();

    if (spare_ != NULL) {

      DeleteArray(spare_);

      spare_ = NULL;

    }

    ASSERT(call_depth_ == 0);

  }

  void BeginDeferredScope();

  DeferredHandles* Detach(Object** prev_limit);

  Isolate* isolate_;

  List<internal::Object**> blocks_;

  // Used as a stack to keep track of entered contexts.

  List<Context*> entered_contexts_;

  // Used as a stack to keep track of saved contexts.

  List<Context*> saved_contexts_;

  Object** spare_;

  int call_depth_;

  Object** last_handle_before_deferred_block_;

  // This is only used for threading support.

  v8::ImplementationUtilities::HandleScopeData handle_scope_data_;

  void IterateThis(ObjectVisitor* v);

  char* RestoreThreadHelper(char* from);

  char* ArchiveThreadHelper(char* to);

  friend class DeferredHandles;

  friend class DeferredHandleScope;

  DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);

};

const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page

void HandleScopeImplementer::SaveContext(Context* context) {

  saved_contexts_.Add(context);

}

Context* HandleScopeImplementer::RestoreContext() {

  return saved_contexts_.RemoveLast();

}

bool HandleScopeImplementer::HasSavedContexts() {

  return !saved_contexts_.is_empty();

}

void HandleScopeImplementer::EnterContext(Handle<Context> context) {

  entered_contexts_.Add(*context);

}

bool HandleScopeImplementer::LeaveContext(Handle<Context> context) {

  if (entered_contexts_.is_empty()) return false;

  // TODO(dcarney): figure out what's wrong here

  // if (entered_contexts_.last() != *context) return false;

  entered_contexts_.RemoveLast();

  return true;

}

Handle<Context> HandleScopeImplementer::LastEnteredContext() {

  if (entered_contexts_.is_empty()) return Handle<Context>::null();

  return Handle<Context>(entered_contexts_.last());

}

// If there's a spare block, use it for growing the current scope.

internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {

  internal::Object** block = (spare_ != NULL) ?

      spare_ :

      NewArray<internal::Object*>(kHandleBlockSize);

  spare_ = NULL;

  return block;

}

void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {

  while (!blocks_.is_empty()) {

    internal::Object** block_start = blocks_.last();

    internal::Object** block_limit = block_start + kHandleBlockSize;

#ifdef DEBUG

    // SealHandleScope may make the prev_limit to point inside the block.

    if (block_start <= prev_limit && prev_limit <= block_limit) {

#ifdef ENABLE_HANDLE_ZAPPING

      internal::HandleScope::ZapRange(prev_limit, block_limit);

#endif

      break;

    }

#else

    if (prev_limit == block_limit) break;

#endif

    blocks_.RemoveLast();

#ifdef ENABLE_HANDLE_ZAPPING

    internal::HandleScope::ZapRange(block_start, block_limit);

#endif

    if (spare_ != NULL) {

      DeleteArray(spare_);

    }

    spare_ = block_start;

  }

  ASSERT((blocks_.is_empty() && prev_limit == NULL) ||

         (!blocks_.is_empty() && prev_limit != NULL));

}

// Interceptor functions called from generated inline caches to notify

// CPU profiler that external callbacks are invoked.

void InvokeAccessorGetterCallback(

    v8::Local<v8::String> property,

    const v8::PropertyCallbackInfo<v8::Value>& info,

    v8::AccessorGetterCallback getter);

void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,

                            v8::FunctionCallback callback);

class Testing {

 public:

  static v8::Testing::StressType stress_type() { return stress_type_; }

  static void set_stress_type(v8::Testing::StressType stress_type) {

    stress_type_ = stress_type;

  }

 private:

  static v8::Testing::StressType stress_type_;

};

} }  // namespace v8::internal

#endif  // V8_API_H_