handle.h revision a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7 
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
10namespace 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.
16template<typename T>
17class Handle {
18 public:
19  Handle() : object_(NULL) {}
20
21  Handle(v8::Handle<v8::Value> wrapper, T* object)
22    : wrapper_(wrapper),
23      object_(object) {
24  }
25
26  bool IsEmpty() const { return !object_; }
27
28  void Clear() {
29    wrapper_.Clear();
30    object_ = NULL;
31  }
32
33  T* operator->() const { return object_; }
34  v8::Handle<v8::Value> ToV8() { return wrapper_; }
35  T* get() const { return object_; }
36
37 private:
38  v8::Handle<v8::Value> wrapper_;
39  T* object_;
40};
41
42template<typename T>
43struct 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    Converter<T*>::FromV8(isolate, val, &object);
52    return gin::Handle<T>(val, object);
53  }
54};
55
56// This function is a convenient way to create a handle from a raw pointer
57// without having to write out the type of the object explicitly.
58template<typename T>
59gin::Handle<T> CreateHandle(v8::Isolate* isolate, T* object) {
60  return gin::Handle<T>(object->GetWrapper(isolate), object);
61}
62
63}  // namespace gin
64
65#endif  // GIN_HANDLE_H_
66