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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_COMMON_STD_DEFAULT_ACCESSOR_HH
#define DUNE_COMMON_STD_DEFAULT_ACCESSOR_HH
#include <type_traits>
namespace Dune::Std {
/**
* \brief A type for indexed access to elements of mdspan.
* \ingroup CxxUtilities
*
* The `default_accessor` class template is the default `AccessorPolicy` used by `mdspan`
* if no user-specified accessor policy is provided.
*
* \tparam Element The element type. Shall be a complete object type that is neither an
* abstract class type nor an array type. Otherwise, the program is ill-formed.
*/
template <class Element>
class default_accessor
{
public:
using element_type = Element;
using data_handle_type = element_type*;
using reference = element_type&;
using offset_policy = default_accessor;
public:
// [mdspan.accessor.default.overview]
/// \brief Default constructor
constexpr default_accessor () noexcept = default;
/// \brief Converting constructor from an accessor with different element type
template <class OtherElement,
std::enable_if_t<std::is_convertible_v<OtherElement(*)[], Element(*)[]>, int> = 0>
constexpr default_accessor (default_accessor<OtherElement>) noexcept {}
/// \brief Return a reference to the i'th element in the data range starting at `p`
constexpr reference access (data_handle_type p, std::size_t i) const noexcept
{
return p[i];
}
/// \brief Return a data handle to the i'th element in the data range starting at `p`
constexpr data_handle_type offset (data_handle_type p, std::size_t i) const noexcept
{
return p + i;
}
};
} // end namespace Dune::Std
#endif // DUNE_COMMON_STD_DEFAULT_ACCESSOR_HH
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