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Observer.hpp

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/*******************************************************************************
 * This file is part of openWNS (open Wireless Network Simulator)
 * _____________________________________________________________________________
 *
 * Copyright (C) 2004-2007
 * Chair of Communication Networks (ComNets)
 * Kopernikusstr. 16, D-52074 Aachen, Germany
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 * fax: ++49-241-80-22242
 * email: info@openwns.org
 * www: http://www.openwns.org
 * _____________________________________________________________________________
 *
 * openWNS is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 2 as published by the
 * Free Software Foundation;
 *
 * openWNS is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
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#ifndef WNS_OBSERVER_HPP
#define WNS_OBSERVER_HPP

#include <WNS/Assure.hpp>
#include <WNS/SubjectInterface.hpp>
#include <WNS/ObserverInterface.hpp>

#include <list>
#include <algorithm>
namespace wns {

    template <typename NOTIFICATIONINTERFACE>
    class Observer :
        virtual public ObserverInterface<NOTIFICATIONINTERFACE>
    {
    public:
        typedef NOTIFICATIONINTERFACE NotificationInterface;

        typedef ObserverInterface<NotificationInterface> ObserverType;

        typedef SubjectInterface<ObserverType> SubjectType;

        Observer() :
            subjects()
        {
        }

        Observer(const Observer& other) :
            NotificationInterface(other),
            ObserverInterface<NOTIFICATIONINTERFACE>(other),
            subjects(other.subjects)
        {
            this->forEachSubject(
                std::bind2nd(
                    std::mem_fun(&SubjectType::addObserver),
                    this));
        }

        Observer&
        operator=(const Observer& other)
        {
            // remove own observers
            this->forEachSubject(
                std::bind2nd(
                    std::mem_fun(&SubjectType::removeObserver),
                    this));

            // copy subjects from other
            subjects = other.subjects;

            // observe these subjects
            this->forEachSubject(
                std::bind2nd(
                    std::mem_fun(&SubjectType::addObserver),
                    this));

            return *this;
        }

        virtual
        ~Observer()
        {
            this->forEachSubject(
                std::bind2nd(
                    std::mem_fun(&SubjectType::removeObserver),
                    this));
        }

        void
        startObserving(SubjectType* subject)
        {
            subject->addObserver(this);
            this->addSubject(subject);
        }

        void
        stopObserving(SubjectType* subject)
        {
            subject->removeObserver(this);
            this->removeSubject(subject);
        }

    private:
        virtual void
        addSubject(SubjectType* subject)
        {
            assureNotNull(subject);
            assure(
                find(this->subjects.begin(), this->subjects.end(), subject) == this->subjects.end(),
                "Already registered");
            this->subjects.push_back(subject);
        }

        virtual void
        removeSubject(SubjectType* subject)
        {
            assureNotNull(subject);
            assure(
                find(this->subjects.begin(), this->subjects.end(), subject) != this->subjects.end(),
                "Not registered");

            this->subjects.erase(find(this->subjects.begin(), this->subjects.end(), subject));
        }

        template <typename FUNCTOR>
        FUNCTOR
        forEachSubject(const FUNCTOR& functor)
        {
            // copy, so the container gets not corrupted during for_each ...
            SubjectContainer tmp = this->subjects;
            return std::for_each(tmp.begin(), tmp.end(), functor);
        }

        typedef std::list<SubjectType*> SubjectContainer;

        SubjectContainer subjects;
    };
} // wns

#endif

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