multimapperview.hh

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// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
//
// SPDX-FileCopyrightText: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
// SPDX-License-Identifier: GPL-3.0-or-later
//
#ifndef DUMUX_COMMON_MULTIMAPPERVIEW_HH
#define DUMUX_COMMON_MULTIMAPPERVIEW_HH
 
#include <array>
 
namespace Dumux::Detail {
 
template<class Mapper>
class MultiMapperView
{
public:
    explicit constexpr MultiMapperView(const Mapper& mapper)
    : mapper_(mapper)
    {}
 
    template<class Entity>
    decltype(auto) index(const Entity& entity) const
    { return mapper_.index(entity); }
 
    template<class Entity>
    auto indices(const Entity& entity) const
    {
        if constexpr (requires { mapper_.indices(entity); })
            return mapper_.indices(entity);
        else
            return std::array<decltype(mapper_.index(entity)), 1>{ mapper_.index(entity) };
    }
 
private:
    const Mapper& mapper_;
};
 
} // end namespace Dumux::Detail
 
namespace Dumux {
 
template<class Mapper>
constexpr auto asMultiMapper(const Mapper& mapper)
{
    return Detail::MultiMapperView<Mapper>(mapper);
}
 
} // end namespace Dumux
 
#endif