nil.H

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/*---------------------------------------------------------------------------*\
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    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
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-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM 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.
 
    OpenFOAM 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 OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::nil
 
Description
    A zero-sized class without any storage. Used, for example, in HashSet.
 
    Note:
        A zero-sized class actually does still require at least 1 byte storage.
 
\*---------------------------------------------------------------------------*/
 
#ifndef nil_H
#define nil_H
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
// Forward declaration of classes
class Istream;
class Ostream;
 
// Forward declaration of friend functions and operators
 
class nil;
 
Istream& operator>>(Istream&, nil&);
Ostream& operator<<(Ostream&, const nil&);
 
 
/*---------------------------------------------------------------------------*\
                             Class nil Declaration
\*---------------------------------------------------------------------------*/
 
class nil
{
 
public:
 
    // Constructors
 
        //- Construct null
        nil()
        {}
 
        //- Construct from Istream
        nil(Istream&)
        {}
 
 
    // IOstream Operators
 
        friend Istream& operator>>(Istream& is, nil&)
        {
            return is;
        }
 
        friend Ostream& operator<<(Ostream& os, const nil&)
        {
            return os;
        }
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //