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objmap.h

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// Copyright (C) 2001 Open Source Telecom Corporation.
//  
// This program 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.
// 
// This program 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.
// 
// As a special exception to the GNU General Public License, permission is 
// granted for additional uses of the text contained in its release 
// of Common C++.
// 
// The exception is that, if you link the Common C++ library with other
// files to produce an executable, this does not by itself cause the
// resulting executable to be covered by the GNU General Public License.
// Your use of that executable is in no way restricted on account of
// linking the Common C++ library code into it.
// 
// This exception does not however invalidate any other reasons why
// the executable file might be covered by the GNU General Public License.
// 
// This exception applies only to the code released under the 
// name Common C++.  If you copy code from other releases into a copy of
// Common C++, as the General Public License permits, the exception does
// not apply to the code that you add in this way.  To avoid misleading
// anyone as to the status of such modified files, you must delete
// this exception notice from them.
// 
// If you write modifications of your own for Common C++, it is your choice
// whether to permit this exception to apply to your modifications.
// If you do not wish that, delete this exception notice.  

namespace ost {

template <class T, class K, unsigned S>
class objMap {
protected:
        static T *objIndex[S];
        T* objNext;
        const K objKey;

        virtual unsigned keyIndex(K k)
        {
                unsigned idx = 0;
                unsigned char *p = (unsigned char *)&k;
                unsigned len = sizeof(K);

                while(len--)
                {
                        idx ^= (idx << 1) ^ *p;
                        ++p;
                }       
                return idx % S;         
        }

        inline unsigned getSize(void)
        {
                return S;
        }

        objMap(const K key)
        {
                unsigned idx = keyIndex(key);
                objKey = key;
                objNext = objIndex[idx];
                objIndex[idx] = (T *)this;
        }
public:
        static T *getObject(keystring key);
};

template <class T, unsigned S>
class keyMap : public objMap<T, keystring, S>
{
        keyMap(keystring key) : objMap<T, keystring, S>(key) {};
        
        unsigned keyIndex(keystring k)
        {
                unsigned idx = 0;
                while(*k)
                {
                        idx = (idx << 1) ^ (unsigned)*k;
                        ++k;
                }
                return idx % S;
        }
};

template <class T, class K, unsigned S>
T *objMap<T, K, S>::objIndex[S](0);

template <class T, class K, unsigned S>
T *objmap<T, K, S>::getObject(const keystring key)
{
        T *obj = objIndex[keyIndex(key)];
        while(obj)
        {
                if(key == obj->objKey)
                        break;
                obj = obj->objNext;
        }
        return obj;
}        

};

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