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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 GIN_HANDLE_H_
6 #define GIN_HANDLE_H_
7 
8 #include "gin/converter.h"
9 
10 namespace gin {
11 
12 // You can use gin::Handle on the stack to retain a gin::Wrappable object.
13 // Currently we don't have a mechanism for retaining a gin::Wrappable object
14 // in the C++ heap because strong references from C++ to V8 can cause memory
15 // leaks.
16 template<typename T>
17 class Handle {
18  public:
Handle()19   Handle() : object_(NULL) {}
20 
Handle(v8::Handle<v8::Value> wrapper,T * object)21   Handle(v8::Handle<v8::Value> wrapper, T* object)
22     : wrapper_(wrapper),
23       object_(object) {
24   }
25 
IsEmpty()26   bool IsEmpty() const { return !object_; }
27 
Clear()28   void Clear() {
29     wrapper_.Clear();
30     object_ = NULL;
31   }
32 
33   T* operator->() const { return object_; }
ToV8()34   v8::Handle<v8::Value> ToV8() const { return wrapper_; }
get()35   T* get() const { return object_; }
36 
37  private:
38   v8::Handle<v8::Value> wrapper_;
39   T* object_;
40 };
41 
42 template<typename T>
43 struct Converter<gin::Handle<T> > {
44   static v8::Handle<v8::Value> ToV8(v8::Isolate* isolate,
45                                     const gin::Handle<T>& val) {
46     return val.ToV8();
47   }
48   static bool FromV8(v8::Isolate* isolate, v8::Handle<v8::Value> val,
49                      gin::Handle<T>* out) {
50     T* object = NULL;
51     if (!Converter<T*>::FromV8(isolate, val, &object)) {
52       return false;
53     }
54     *out = gin::Handle<T>(val, object);
55     return true;
56   }
57 };
58 
59 // This function is a convenient way to create a handle from a raw pointer
60 // without having to write out the type of the object explicitly.
61 template<typename T>
62 gin::Handle<T> CreateHandle(v8::Isolate* isolate, T* object) {
63   v8::Handle<v8::Object> wrapper = object->GetWrapper(isolate);
64   if (wrapper.IsEmpty())
65     return gin::Handle<T>();
66   return gin::Handle<T>(wrapper, object);
67 }
68 
69 }  // namespace gin
70 
71 #endif  // GIN_HANDLE_H_
72