corecel/cont/EnumClassUtils.hh

0001 //----------------------------------*-C++-*----------------------------------//
0002 // Copyright 2023-2024 UT-Battelle, LLC, and other Celeritas developers.
0003 // See the top-level COPYRIGHT file for details.
0004 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
0005 //---------------------------------------------------------------------------//
0006 //! \file corecel/cont/EnumClassUtils.hh
0007 //! \brief Device-friendly utilities for mapping classes to variants
0008 //---------------------------------------------------------------------------//
0009 #pragma once
0010
0011 namespace celeritas
0012 {
0013 //---------------------------------------------------------------------------//
0014 /*!
0015  * Helper struct for mapping enums to classes.
0016  *
0017  * This class can be passed as a "tag" to functors that can then retrieve its
0018  * value or the associated class. It can be implicitly converted into a
0019  * SurfaceType enum for use in template parameters.
0020  */
0021 template<class E, E EV, class T>
0022 struct EnumToClass
0023 {
0024     using enum_type = E;
0025     using type = T;
0026
0027     static constexpr enum_type value = EV;
0028
0029     CELER_CONSTEXPR_FUNCTION operator E() const noexcept { return value; }
0030     CELER_CONSTEXPR_FUNCTION enum_type operator()() const noexcept
0031     {
0032         return value;
0033     }
0034 };
0035
0036 //---------------------------------------------------------------------------//
0037 }  // namespace celeritas