1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/glue/Observer.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,77 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef mozilla_Observer_h
1.10 +#define mozilla_Observer_h
1.11 +
1.12 +#include "nsTArray.h"
1.13 +
1.14 +namespace mozilla {
1.15 +
1.16 +/**
1.17 + * Observer<T> provides a way for a class to observe something.
1.18 + * When an event has to be broadcasted to all Observer<T>, Notify() method
1.19 + * is called.
1.20 + * T represents the type of the object passed in argument to Notify().
1.21 + *
1.22 + * @see ObserverList.
1.23 + */
1.24 +template <class T>
1.25 +class Observer
1.26 +{
1.27 +public:
1.28 + virtual ~Observer() { }
1.29 + virtual void Notify(const T& aParam) = 0;
1.30 +};
1.31 +
1.32 +/**
1.33 + * ObserverList<T> tracks Observer<T> and can notify them when Broadcast() is
1.34 + * called.
1.35 + * T represents the type of the object passed in argument to Broadcast() and
1.36 + * sent to Observer<T> objects through Notify().
1.37 + *
1.38 + * @see Observer.
1.39 + */
1.40 +template <class T>
1.41 +class ObserverList
1.42 +{
1.43 +public:
1.44 + /**
1.45 + * Note: When calling AddObserver, it's up to the caller to make sure the
1.46 + * object isn't going to be release as long as RemoveObserver hasn't been
1.47 + * called.
1.48 + *
1.49 + * @see RemoveObserver()
1.50 + */
1.51 + void AddObserver(Observer<T>* aObserver) {
1.52 + mObservers.AppendElement(aObserver);
1.53 + }
1.54 +
1.55 + /**
1.56 + * Remove the observer from the observer list.
1.57 + * @return Whether the observer has been found in the list.
1.58 + */
1.59 + bool RemoveObserver(Observer<T>* aObserver) {
1.60 + return mObservers.RemoveElement(aObserver);
1.61 + }
1.62 +
1.63 + uint32_t Length() {
1.64 + return mObservers.Length();
1.65 + }
1.66 +
1.67 + void Broadcast(const T& aParam) {
1.68 + uint32_t size = mObservers.Length();
1.69 + for (uint32_t i=0; i<size; ++i) {
1.70 + mObservers[i]->Notify(aParam);
1.71 + }
1.72 + }
1.73 +
1.74 +protected:
1.75 + nsTArray<Observer<T>*> mObservers;
1.76 +};
1.77 +
1.78 +} // namespace mozilla
1.79 +
1.80 +#endif // mozilla_Observer_h
