gin/handle.h

   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:
  19   Handle() : object_(NULL) {}
  20
  21   Handle(v8::Local<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::Local<v8::Value> ToV8() const { return wrapper_; }
  35   T* get() const { return object_; }
  36
  37  private:
  38   v8::Local<v8::Value> wrapper_;
  39   T* object_;
  40 };
  41
  42 template<typename T>
  43 struct Converter<gin::Handle<T> > {
  44   static v8::Local<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::Local<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::Local<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_