factory.hpp

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/* factory.hpp                                
 *
 * Copyright (C) 2003 Sawtooth Consulting Ltd.
 *
 * This file is part of yaSSL.
 *
 * yaSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * yaSSL 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

/*  The factory header defines an Object Factory, used by SSL message and
 *  handshake types.
 *
 *  See Desgin Pattern in GoF and Alexandrescu's chapter in Modern C++ Design,
 *  page 208
 */



#ifndef yaSSL_FACTORY_HPP
#define yaSSL_FACTORY_HPP

#include "vector.hpp"
#include "pair.hpp"



// VC60 workaround: it doesn't allow typename in some places
#if defined(_MSC_VER) && (_MSC_VER < 1300)
    #define CPP_TYPENAME
#else
    #define CPP_TYPENAME typename
#endif


namespace yaSSL {


// Factory uses its callback map to create objects by id,
// returning an abstract base pointer
template<class    AbstractProduct, 
         typename IdentifierType = int, 
         typename ProductCreator = AbstractProduct* (*)()
        >
class Factory {                                             
    typedef mySTL::pair<IdentifierType, ProductCreator> CallBack;
    typedef mySTL::vector<CallBack> CallBackVector;

    CallBackVector callbacks_;
public:
    // pass function pointer to register all callbacks upon creation
    explicit Factory(void (*init)(Factory<AbstractProduct, IdentifierType,
                                  ProductCreator>&))
    { 
        init(*this); 
    }

    // reserve place in vector before registering, used by init funcion
    void Reserve(size_t sz)
    {
        callbacks_.reserve(sz);
    }

    // register callback
    void Register(const IdentifierType& id, ProductCreator pc)
    {
        callbacks_.push_back(mySTL::make_pair(id, pc));
    }

    // THE Creator, returns a new object of the proper type or 0
    AbstractProduct* CreateObject(const IdentifierType& id) const
    {
        const CallBack* first = callbacks_.begin();
        const CallBack* last  = callbacks_.end();

        while (first != last) {
            if (first->first == id)
                break;
            ++first;
        }

        if (first == callbacks_.end())
            return 0;
        return (first->second)();
    }
private:
    Factory(const Factory&);            // hide copy
    Factory& operator=(const Factory&); // and assign
};


} // naemspace

#endif // yaSSL_FACTORY_HPP