id_man.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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 3 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 ULTIMA8_MISC_IDMAN_H
#define ULTIMA8_MISC_IDMAN_H

#include "common/array.h"

namespace Common {
class ReadStream;
class WriteStream;
}

namespace Ultima {
namespace Ultima8 {

//
// idMan. Used to allocate and keep track of unused ids.
// Supposed to be used by Kernel and World for pID and ObjId
//
// The idMan itself uses a nifty linked list that is also an array.
// As such it has the advantages of both. Adds and removals are fast,
// As is checking to see if an ID is used.
//
// idMan works as a LILO (last in last out) for id recycling. So an id that has
// been cleared will not be used until all other currently unused ids have been
// allocated.
//

class idMan {
    uint16      _begin;          
    uint16      _end;            
    uint16      _maxEnd;         
    uint16      _startCount;     

    uint16      _usedCount;      

    Common::Array<uint16> _ids;    
    uint16      _first;          
    uint16      _last;           
public:
    idMan(uint16 begin, uint16 max_end, uint16 startcount = 0);
    ~idMan();

    bool        isFull() const {
        return _first == 0 && _end >= _maxEnd;
    }

    void        clearAll(uint16 new_max = 0);

    uint16      getNewID();

    bool        reserveID(uint16 id);

    void        clearID(uint16 id);

    bool        isIDUsed(uint16 id) const {
        return id >= _begin && id <= _end && _ids[id] == 0 && id != _last;
    }

    void        setNewMax(uint16 maxEnd) {
        _maxEnd = maxEnd;
    }

    void save(Common::WriteStream *ws) const;
    bool load(Common::ReadStream *rs, uint32 version);

private:
    void expand();
};

} // End of namespace Ultima8
} // End of namespace Ultima

#endif