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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.
/**
* @file objmap.h
* @short Template for creating hash indexed objects.
**/
#include <cc++/strchar.h>
namespace ost {
/**
* Used to create and manage a hash index of objects through a common
* type. The objects can be examined and a specific instance located
* by a hash key.
*
* @author David Sugar <dyfet@gnutelephony.org>
* @short hash indexed searchable template chain.
*/
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;
}
} // namespace
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