/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef mozilla_Observer_h #define mozilla_Observer_h #include "nsTArray.h" namespace mozilla { /** * Observer<T> provides a way for a class to observe something. * When an event has to be broadcasted to all Observer<T>, Notify() method * is called. * T represents the type of the object passed in argument to Notify(). * * @see ObserverList. */ template<class T> class Observer { public: virtual ~Observer() {} virtual void Notify(const T& aParam) = 0; }; /** * ObserverList<T> tracks Observer<T> and can notify them when Broadcast() is * called. * T represents the type of the object passed in argument to Broadcast() and * sent to Observer<T> objects through Notify(). * * @see Observer. */ template<class T> class ObserverList { public: /** * Note: When calling AddObserver, it's up to the caller to make sure the * object isn't going to be release as long as RemoveObserver hasn't been * called. * * @see RemoveObserver() */ void AddObserver(Observer<T>* aObserver) { mObservers.AppendElement(aObserver); } /** * Remove the observer from the observer list. * @return Whether the observer has been found in the list. */ bool RemoveObserver(Observer<T>* aObserver) { return mObservers.RemoveElement(aObserver); } uint32_t Length() { return mObservers.Length(); } void Broadcast(const T& aParam) { nsTArray<Observer<T>*> observersCopy(mObservers); uint32_t size = observersCopy.Length(); for (uint32_t i = 0; i < size; ++i) { observersCopy[i]->Notify(aParam); } } protected: nsTArray<Observer<T>*> mObservers; }; } // namespace mozilla #endif // mozilla_Observer_h