predicates.H

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/*---------------------------------------------------------------------------*\
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   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
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-------------------------------------------------------------------------------
    Copyright (C) 2017-2018 OpenCFD Ltd.
-------------------------------------------------------------------------------
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/>.
 
Namespace
    Foam::predicates
 
Description
    Constant predicate types.
 
SourceFiles
    predicates.H
 
\*---------------------------------------------------------------------------*/
 
#ifndef predicates_H
#define predicates_H
 
#include <string>
#include <type_traits>
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
namespace predicates
{
 
/*---------------------------------------------------------------------------*\
                           Class always Declaration
\*---------------------------------------------------------------------------*/
 
//- Unary and binary predicates that always return true, useful for templating.
struct always : std::true_type
{
    //- Unary predicate
    //  \return true
    template<class T>
    constexpr bool operator()(const T&) const noexcept
    {
        return value;
    }
 
    //- Binary predicate
    //  \return true
    template<class T1, class T2>
    constexpr bool operator()(const T1&, const T2&) const noexcept
    {
        return value;
    }
 
    //- String match
    //  \return true
    constexpr bool match(const std::string&, bool literal=false) const noexcept
    {
        return value;
    }
};
 
 
/*---------------------------------------------------------------------------*\
                            Class never Declaration
\*---------------------------------------------------------------------------*/
 
//- Unary and binary predicates that never return true, useful for templating.
struct never : std::false_type
{
    //- Unary predicate
    //  \return false
    template<class T>
    constexpr bool operator()(const T&) const noexcept
    {
        return value;
    }
 
    //- Binary predicate
    //  \return false
    template<class T1, class T2>
    constexpr bool operator()(const T1&, const T2&) const noexcept
    {
        return value;
    }
 
    //- String match
    //  \return false
    constexpr bool match(const std::string&, bool literal=false) const noexcept
    {
        return value;
    }
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace predicates
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //