/*
 * Copyright 2006, Haiku.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *              Stephan Aßmus <superstippi@gmx.de>
 */

#ifndef OBSERVABLE_H
#define OBSERVABLE_H

#include <List.h>

class Observer;

class Observable {
 public:
                                                                Observable();
        virtual                                         ~Observable();

                        bool                            AddObserver(Observer* observer);
                        bool                            RemoveObserver(Observer* observer);

                        int32                           CountObservers() const;
                        Observer*                       ObserverAtFast(int32 index) const;
        
                        void                            Notify() const;

                        void                            SuspendNotifications(bool suspend);

                        bool                            HasPendingNotifications() const
                                                                        { return fPendingNotifications; }

 private:
                        BList                           fObservers;

                        int32                           fSuspended;
        mutable bool                            fPendingNotifications;
};

class AutoNotificationSuspender {
 public:
                                                                AutoNotificationSuspender(Observable* object)
                                                                        : fObject(object)
                                                                {
                                                                        fObject->SuspendNotifications(true);
                                                                }

        virtual                                         ~AutoNotificationSuspender()
                                                                {
                                                                        fObject->SuspendNotifications(false);
                                                                }
 private:
                        Observable*                     fObject;
};

#endif // OBSERVABLE_H