intrusive_list.h

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2017 CERN
 * Copyright (C) 2021 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * @author Tomasz Wlostowski <[email protected]>
 *
 * 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, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#ifndef INTRUSIVE_LIST_H
#define INTRUSIVE_LIST_H

template <class T>
class INTRUSIVE_LIST
{
public:
 INTRUSIVE_LIST<T>()
 {
 ListClear();
 }

 void ListClear()
 {
 m_prev = nullptr;
 m_next = nullptr;
 m_root = (T*) this;
 m_count = 1;
 }

 T* ListRemove()
 {
 if( m_prev )
 m_prev->m_next = m_next;

 if( m_next )
 m_next->m_prev = m_prev;

 m_root->m_count--;

 T* rv = nullptr;

 if( m_prev )
 rv = m_prev;
 else if( m_next )
 rv = m_next;

 m_root = nullptr;
 m_prev = nullptr;
 m_next = nullptr;
 return rv;
 }

 int ListSize() const
 {
 return m_root ? m_root->m_count : 0;
 }

 void ListInsert( T* item )
 {
 if( !m_root )
 m_root = item;

 if( m_next )
 m_next->m_prev = item;

 item->m_prev = (T*) this;
 item->m_next = m_next;
 item->m_root = m_root;
 m_root->m_count++;

 m_next = item;
 }

 T* ListNext() const { return m_next; };
 T* ListPrev() const { return m_prev; };

private:
 int m_count;
 T* m_prev;
 T* m_next;
 T* m_root;
};

#endif /* INTRUSIVE_LIST_H */