1// Copyright 2013 The Chromium 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 CHROME_RENDERER_EXTENSIONS_SCOPED_PERSISTENT_H_ 6#define CHROME_RENDERER_EXTENSIONS_SCOPED_PERSISTENT_H_ 7 8#include "base/logging.h" 9#include "v8/include/v8.h" 10 11namespace extensions { 12 13// A v8::Persistent handle to a V8 value which destroys and clears the 14// underlying handle on destruction. 15template <typename T> 16class ScopedPersistent { 17 public: 18 ScopedPersistent() { 19 } 20 21 explicit ScopedPersistent(v8::Handle<T> handle) { 22 reset(handle); 23 } 24 25 ~ScopedPersistent() { 26 reset(); 27 } 28 29 void reset(v8::Handle<T> handle) { 30 if (!handle.IsEmpty()) 31 handle_.Reset(GetIsolate(handle), handle); 32 else 33 reset(); 34 } 35 36 void reset() { 37 if (handle_.IsEmpty()) 38 return; 39 handle_.Dispose(); 40 handle_.Clear(); 41 } 42 43 v8::Handle<T> operator->() const { 44 return get(); 45 } 46 47 // TODO(dcarney): Remove this function 48 // This is an unsafe access to the underlying handle 49 v8::Handle<T> get() const { 50 return *reinterpret_cast<v8::Handle<T>*>( 51 const_cast<v8::Persistent<T>* >(&handle_)); 52 } 53 54 v8::Handle<T> NewHandle() const { 55 if (handle_.IsEmpty()) 56 return v8::Local<T>(); 57 return v8::Local<T>::New(GetIsolate(handle_), handle_); 58 } 59 60 template<typename P> 61 void MakeWeak(P* parameters, 62 typename v8::WeakReferenceCallbacks<T, P>::Revivable callback) { 63 handle_.MakeWeak(parameters, callback); 64 } 65 66 private: 67 template <typename U> 68 static v8::Isolate* GetIsolate(v8::Handle<U> object_handle) { 69 // Only works for v8::Object and its subclasses. Add specialisations for 70 // anything else. 71 if (!object_handle.IsEmpty()) 72 return GetIsolate(object_handle->CreationContext()); 73 return v8::Isolate::GetCurrent(); 74 } 75 static v8::Isolate* GetIsolate(v8::Handle<v8::Context> context_handle) { 76 if (!context_handle.IsEmpty()) 77 return context_handle->GetIsolate(); 78 return v8::Isolate::GetCurrent(); 79 } 80 static v8::Isolate* GetIsolate( 81 v8::Handle<v8::ObjectTemplate> template_handle) { 82 return v8::Isolate::GetCurrent(); 83 } 84 85 v8::Persistent<T> handle_; 86 87 DISALLOW_COPY_AND_ASSIGN(ScopedPersistent); 88}; 89 90} // namespace extensions 91 92#endif // CHROME_RENDERER_EXTENSIONS_SCOPED_PERSISTENT_H_ 93