133 lines
3.9 KiB
C++
133 lines
3.9 KiB
C++
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE.chromium file.
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#ifndef NATIVE_MATE_WRAPPABLE_H_
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#define NATIVE_MATE_WRAPPABLE_H_
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#include "native_mate/compat.h"
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#include "native_mate/converter.h"
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#include "native_mate/template_util.h"
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namespace mate {
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namespace internal {
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struct Destroyable;
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void* FromV8Impl(v8::Isolate* isolate, v8::Local<v8::Value> val);
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} // namespace internal
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// Wrappable is a base class for C++ objects that have corresponding v8 wrapper
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// objects. To retain a Wrappable object on the stack, use a gin::Handle.
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//
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// USAGE:
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// // my_class.h
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// class MyClass : Wrappable<MyClass> {
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// public:
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// ...
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// };
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//
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// Subclasses should also typically have private constructors and expose a
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// static Create function that returns a mate::Handle. Forcing creators through
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// this static Create function will enforce that clients actually create a
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// wrapper for the object. If clients fail to create a wrapper for a wrappable
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// object, the object will leak because we use the weak callback from the
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// wrapper as the signal to delete the wrapped object.
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class WrappableBase {
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public:
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WrappableBase();
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virtual ~WrappableBase();
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// Retrieve the v8 wrapper object cooresponding to this object.
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v8::Local<v8::Object> GetWrapper();
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// Returns the Isolate this object is created in.
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v8::Isolate* isolate() const { return isolate_; }
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protected:
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// Called after the "_init" method gets called in JavaScript.
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virtual void AfterInit(v8::Isolate* isolate) {}
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// Bind the C++ class to the JS wrapper.
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// This method should only be called by classes using Constructor.
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virtual void InitWith(v8::Isolate* isolate, v8::Local<v8::Object> wrapper);
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private:
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friend struct internal::Destroyable;
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static void FirstWeakCallback(
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const v8::WeakCallbackInfo<WrappableBase>& data);
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static void SecondWeakCallback(
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const v8::WeakCallbackInfo<WrappableBase>& data);
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v8::Isolate* isolate_;
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v8::Global<v8::Object> wrapper_; // Weak
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DISALLOW_COPY_AND_ASSIGN(WrappableBase);
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};
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template<typename T>
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class Wrappable : public WrappableBase {
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public:
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Wrappable() {}
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protected:
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// Init the class with T::BuildPrototype.
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void Init(v8::Isolate* isolate) {
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// Fill the object template.
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if (!templ_) {
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v8::Local<v8::FunctionTemplate> templ = v8::FunctionTemplate::New(isolate);
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T::BuildPrototype(isolate, templ->PrototypeTemplate());
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templ_ = new v8::Global<v8::FunctionTemplate>(isolate, templ);
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}
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v8::Local<v8::Object> wrapper;
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v8::Local<v8::FunctionTemplate> templ =
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v8::Local<v8::FunctionTemplate>::New(isolate, *templ_);
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// |wrapper| may be empty in some extreme cases, e.g., when
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// Object.prototype.constructor is overwritten.
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if (!templ->PrototypeTemplate()->NewInstance(
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isolate->GetCurrentContext()).ToLocal(&wrapper)) {
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// The current wrappable object will be no longer managed by V8. Delete
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// this now.
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delete this;
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return;
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}
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InitWith(isolate, wrapper);
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}
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private:
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static v8::Global<v8::FunctionTemplate>* templ_; // Leaked on purpose
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DISALLOW_COPY_AND_ASSIGN(Wrappable);
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};
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// static
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template<typename T>
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v8::Global<v8::FunctionTemplate>* Wrappable<T>::templ_ = nullptr;
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// This converter handles any subclass of Wrappable.
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template <typename T>
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struct Converter<T*,
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typename std::enable_if<
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std::is_convertible<T*, WrappableBase*>::value>::type> {
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static v8::Local<v8::Value> ToV8(v8::Isolate* isolate, T* val) {
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if (val)
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return val->GetWrapper();
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else
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return v8::Null(isolate);
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}
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static bool FromV8(v8::Isolate* isolate, v8::Local<v8::Value> val, T** out) {
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*out = static_cast<T*>(static_cast<WrappableBase*>(
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internal::FromV8Impl(isolate, val)));
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return *out != nullptr;
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}
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};
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} // namespace mate
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#endif // NATIVE_MATE_WRAPPABLE_H_
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