electron/native_mate/wrappable.h
2015-07-06 18:16:57 +08:00

111 lines
3.6 KiB
C++

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE.chromium file.
#ifndef NATIVE_MATE_WRAPPABLE_H_
#define NATIVE_MATE_WRAPPABLE_H_
#include "native_mate/compat.h"
#include "native_mate/converter.h"
#include "native_mate/template_util.h"
namespace mate {
namespace internal {
void* FromV8Impl(v8::Isolate* isolate, v8::Local<v8::Value> val);
} // namespace internal
// Wrappable is a base class for C++ objects that have corresponding v8 wrapper
// objects. To retain a Wrappable object on the stack, use a gin::Handle.
//
// USAGE:
// // my_class.h
// class MyClass : Wrappable<MyClass> {
// public:
// // Optional, only required if non-empty template should be used.
// virtual gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
// v8::Isolate* isolate);
// ...
// };
//
// // my_class.cc
// gin::ObjectTemplateBuilder MyClass::GetObjectTemplateBuilder(
// v8::Isolate* isolate) {
// return Wrappable<MyClass>::GetObjectTemplateBuilder(isolate)
// .SetValue("foobar", 42);
// }
//
// Subclasses should also typically have private constructors and expose a
// static Create function that returns a mate::Handle. Forcing creators through
// this static Create function will enforce that clients actually create a
// wrapper for the object. If clients fail to create a wrapper for a wrappable
// object, the object will leak because we use the weak callback from the
// wrapper as the signal to delete the wrapped object.
class ObjectTemplateBuilder;
class Wrappable {
public:
// Retrieve (or create) the v8 wrapper object cooresponding to this object.
// If the type is created via the Constructor, then the GetWrapper would
// return the constructed object, otherwise it would try to create a new
// object constructed by GetObjectTemplateBuilder.
v8::Local<v8::Object> GetWrapper(v8::Isolate* isolate);
// Returns whether this class has been destroyed, users should override this
// method to indicate the native type's state.
virtual bool IsDestroyed() const;
// Returns the Isolate this object is created in.
v8::Isolate* isolate() const { return isolate_; }
// Bind the C++ class to the JS wrapper.
void Wrap(v8::Isolate* isolate, v8::Local<v8::Object> wrapper);
// The user should define T::BuildPrototype if they want to use Constructor
// to build a constructor function for this type.
static void BuildPrototype(v8::Isolate* isolate,
v8::Local<v8::ObjectTemplate> prototype);
protected:
Wrappable();
virtual ~Wrappable();
virtual ObjectTemplateBuilder GetObjectTemplateBuilder(v8::Isolate* isolate);
// Called after the "_init" method gets called in JavaScript.
virtual void AfterInit(v8::Isolate* isolate) {}
private:
static MATE_WEAK_CALLBACK(WeakCallback, v8::Object, Wrappable);
v8::Isolate* isolate_;
v8::UniquePersistent<v8::Object> wrapper_; // Weak
DISALLOW_COPY_AND_ASSIGN(Wrappable);
};
// This converter handles any subclass of Wrappable.
template<typename T>
struct Converter<T*, typename enable_if<
is_convertible<T*, Wrappable*>::value>::type> {
static v8::Local<v8::Value> ToV8(v8::Isolate* isolate, T* val) {
if (val)
return val->GetWrapper(isolate);
else
return v8::Null(isolate);
}
static bool FromV8(v8::Isolate* isolate, v8::Local<v8::Value> val, T** out) {
*out = static_cast<T*>(static_cast<Wrappable*>(
internal::FromV8Impl(isolate, val)));
return *out != NULL;
}
};
} // namespace mate
#endif // NATIVE_MATE_WRAPPABLE_H_