utils/reference_counter.hpp

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/* $Id: reference_counter.hpp 53319 2012-02-29 08:32:13Z shadowmaster $ */
/*
   Copyright (C) 2004 - 2012 by Philippe Plantier <ayin@anathas.org>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org

   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.

   See the COPYING file for more details.
*/

#ifndef UTILS_REFERENCE_COUTER_H_INCLUDED
#define UTILS_REFERENCE_COUTER_H_INCLUDED

/**
 * @file
 */


#include <limits>
#include <boost/static_assert.hpp>

namespace n_ref_counter {


/**
   @class t_ref_counter
   @brief t_ref_counter is a reference counter.  If the counter overflows it stops counting.
   So any negative count disables reference counting.
**/
template <typename T_integral> class t_ref_counter {
    BOOST_STATIC_ASSERT( std::numeric_limits<T_integral>::is_signed);

    T_integral count_;

public:
    enum {NEW=0, NOT_COUNTED = -1};

    explicit t_ref_counter(T_integral x = 0) : count_(x) {}
    t_ref_counter(t_ref_counter const &a) : count_(a.count_) {}
    t_ref_counter & operator=(t_ref_counter const a){count_ = a.count_; return *this;}

    operator T_integral const () const {return count_;}

    T_integral const set(T_integral const a) { count_=a; return count_; }
    T_integral const inc(){
        if (count_ >= 0) { count_  += 1; }
        return count_; }
    T_integral const dec(){
        if( count_ > 0) { count_  -= 1; }
        return count_; }
    T_integral const enable_count(){
        if (count_ < 0) {count_ = 0;}
        return count_; }
    T_integral const disable_count(){
        count_= NOT_COUNTED;
        return count_; }

    T_integral const operator++(){return inc();}
    T_integral const operator++(int){T_integral ret(count_); inc(); return ret;}
    T_integral const operator--(){return dec();}
    T_integral const operator--(int){T_integral ret(count_); dec(); return ret;}
};


}//end namepace

#endif