tristate.h

/* This file is part of the KDE project
   Copyright (C) 2004, 2006 Jaroslaw Staniek <js@iidea.pl>
 
   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library 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
   Library General Public License for more details.
 
   You should have received a copy of the GNU Library General Public License
   along with this program; see the file COPYING.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
*/
 
#ifndef _TRISTATE_TYPE_H_
#define _TRISTATE_TYPE_H_
 
#include <tqstring.h>

static const char cancelled = 2;

static const char dontKnow = cancelled;

class tristate
{
public:
    tristate()
     : m_value(Cancelled)
    {
    }

    tristate(bool boolValue)
     : m_value(boolValue ? True : False)
    {
    }

    tristate(char c)
     : m_value(c==cancelled ? tristate::Cancelled : (c==1 ? True : False))
    {
    }

    tristate(int intValue)
     : m_value(intValue==(int)cancelled ? tristate::Cancelled : (intValue==1 ? True : False))
    {
    }

    bool operator!() const { return m_value==False; }

    bool operator~() const { return m_value==Cancelled; }
 
    tristate& operator=(const tristate& tsValue) { m_value = tsValue.m_value; return *this; }
 
    friend inline bool operator==(bool boolValue, tristate tsValue);
 
    friend inline bool operator==(tristate tsValue, bool boolValue);
 
    friend inline bool operator!=(bool boolValue, tristate tsValue);
 
    friend inline bool operator!=(tristate tsValue, bool boolValue);

    TQString toString() const {
        if (m_value==False)
            return TQString::fromLatin1("false");
        return m_value==True ? TQString::fromLatin1("true") : TQString::fromLatin1("cancelled");
    }
 
private:
    enum Value {
        False = 0,
        True = 1,
        Cancelled = 2
    };

    Value m_value;
};

inline bool operator!=(bool boolValue, tristate tsValue) 
{
    return !( (tsValue.m_value==tristate::True && boolValue) 
    || (tsValue.m_value==tristate::False && !boolValue) );
}

inline bool operator!=(tristate tsValue, bool boolValue) 
{
    return !( (tsValue.m_value==tristate::True && boolValue) 
    || (tsValue.m_value==tristate::False && !boolValue) );
}

inline bool operator==(tristate tsValue, bool boolValue)
{
    return (tsValue.m_value==tristate::True && boolValue) 
    || (tsValue.m_value==tristate::False && !boolValue);
}

inline bool operator==(bool boolValue, tristate tsValue)
{
    return (tsValue.m_value==tristate::True && boolValue) 
    || (tsValue.m_value==tristate::False && !boolValue);
}
 
#endif