Reference.h

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/*
 * Copyright (C) 2008-2016 TrinityCore <http://www.trinitycore.org/>
 * Copyright (C) 2005-2009 MaNGOS <http://getmangos.com/>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#ifndef _REFERENCE_H
#define _REFERENCE_H

#include "Dynamic/LinkedList.h"
#include "Errors.h" // for ASSERT

//=====================================================

template <class TO, class FROM> class Reference : public LinkedListElement
{
 private:
 TO* iRefTo;
 FROM* iRefFrom;
 protected:
 // Tell our refTo (target) object that we have a link
 virtual void targetObjectBuildLink() = 0;

 // Tell our refTo (taget) object, that the link is cut
 virtual void targetObjectDestroyLink() = 0;

 // Tell our refFrom (source) object, that the link is cut (Target destroyed)
 virtual void sourceObjectDestroyLink() = 0;
 public:
 Reference() { iRefTo = NULL; iRefFrom = NULL; }
 virtual ~Reference() { }

 // Create new link
 void link(TO* toObj, FROM* fromObj)
 {
 ASSERT(fromObj); // fromObj MUST not be NULL
 if (isValid())
 unlink();
 if (toObj != NULL)
 {
 iRefTo = toObj;
 iRefFrom = fromObj;
 targetObjectBuildLink();
 }
 }

 // We don't need the reference anymore. Call comes from the refFrom object
 // Tell our refTo object, that the link is cut
 void unlink()
 {
 targetObjectDestroyLink();
 delink();
 iRefTo = NULL;
 iRefFrom = NULL;
 }

 // Link is invalid due to destruction of referenced target object. Call comes from the refTo object
 // Tell our refFrom object, that the link is cut
 void invalidate() // the iRefFrom MUST remain!!
 {
 sourceObjectDestroyLink();
 delink();
 iRefTo = NULL;
 }

 bool isValid() const // Only check the iRefTo
 {
 return iRefTo != NULL;
 }

 Reference<TO, FROM> * next() { return((Reference<TO, FROM> *) LinkedListElement::next()); }
 Reference<TO, FROM> const* next() const { return((Reference<TO, FROM> const*) LinkedListElement::next()); }
 Reference<TO, FROM> * prev() { return((Reference<TO, FROM> *) LinkedListElement::prev()); }
 Reference<TO, FROM> const* prev() const { return((Reference<TO, FROM> const*) LinkedListElement::prev()); }

 Reference<TO, FROM> * nocheck_next() { return((Reference<TO, FROM> *) LinkedListElement::nocheck_next()); }
 Reference<TO, FROM> const* nocheck_next() const { return((Reference<TO, FROM> const*) LinkedListElement::nocheck_next()); }
 Reference<TO, FROM> * nocheck_prev() { return((Reference<TO, FROM> *) LinkedListElement::nocheck_prev()); }
 Reference<TO, FROM> const* nocheck_prev() const { return((Reference<TO, FROM> const*) LinkedListElement::nocheck_prev()); }

 TO* operator ->() const { return iRefTo; }
 TO* getTarget() const { return iRefTo; }

 FROM* GetSource() const { return iRefFrom; }

 private:
 Reference(Reference const&);
 Reference& operator=(Reference const&);
};

//=====================================================
#endif