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Chamaeleon.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
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 * _____________________________________________________________________________
 *
 * 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_CHAMAELEON_HPP
#define WNS_CHAMAELEON_HPP

#include <WNS/TypeInfo.hpp>
#include <WNS/Exception.hpp>

namespace wns {

    template <typename T> class Chamaeleon;

    class ChamaeleonBase
    {
    public:
        class BadCast :
            public Exception
        {
        public:
            BadCast(
                const TypeInfo& expectedType,
                const TypeInfo& actualType) throw();

            virtual
            ~BadCast() throw();
        };

        // Default copy constructor is ok

        virtual
        ~ChamaeleonBase() throw();

        TypeInfo
        getTypeInfo() const throw();

        template <typename T>
        Chamaeleon<T>*
        downCast() throw(BadCast)
        {
            Chamaeleon<T>* chamaeleon = dynamic_cast<Chamaeleon<T>*>(this);
            if(NULL == chamaeleon)
            {
                throw BadCast(TypeInfo::create<T>(), getTypeInfo());
            }
            return chamaeleon;
        }

    protected:
        explicit
        ChamaeleonBase(const TypeInfo& typeInfo) throw();

    private:
        TypeInfo typeInfo_;
    };

    template <typename VALUETYPE>
    class Chamaeleon :
        public ChamaeleonBase
    {
        template<class> friend class Chamaeleon;
    public:
        typedef VALUETYPE ValueType;

        explicit
        Chamaeleon(ValueType data) throw() :
            ChamaeleonBase(TypeInfo::create<ValueType>()),
            data_(data)
        {
        }

        // Default copy c'tor is ok

        template <typename U>
        explicit
        Chamaeleon(const Chamaeleon<U>& other) throw() :
            ChamaeleonBase(other),
            data_(other.data_)
        {
        }

        virtual
        ~Chamaeleon() throw()
        {
        }

        ValueType
        unHide() const throw()
        {
            return data_;
        }

        template <typename U>
        Chamaeleon&
        operator =(const Chamaeleon<U>& other) throw()
        {
            data_ = other.data_;
            return *this;
        }

    private:
        ValueType data_;
    };
}

#endif // NOT defined WNS_CHAMAELEON_HPP

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