corecel/io/EnumStringMapper.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/io/EnumStringMapper.hh
0007 //---------------------------------------------------------------------------//
0008 #pragma once
0009
0010 #include <type_traits>
0011
0012 #include "corecel/Assert.hh"
0013 #include "corecel/cont/Array.hh"
0014
0015 #include "detail/EnumStringMapperImpl.hh"
0016
0017 namespace celeritas
0018 {
0019 //---------------------------------------------------------------------------//
0020 /*!
0021  * Map enums to strings for user output.
0022  *
0023  * This should generally be a static const class.
0024  *
0025  * Example:
0026  * \code
0027     char const* to_cstring(Foo value)
0028     {
0029         static EnumStringMapper<Foo> const convert{"foo", "bar", "baz"};
0030         return convert(value);
0031     }
0032  * \endcode
0033  */
0034 template<class T>
0035 class EnumStringMapper
0036 {
0037     static_assert(std::is_enum<T>::value, "not an enum type");
0038     static_assert(static_cast<int>(T::size_) >= 0, "invalid enum type");
0039
0040   public:
0041     //! Construct with one string per valid enum value
0042     template<class... Ts>
0043     explicit CELER_CONSTEXPR_FUNCTION EnumStringMapper(Ts... strings)
0044         : strings_{strings..., detail::g_invalid_string}
0045     {
0046         // Protect against leaving off a string
0047         static_assert(sizeof...(strings) == static_cast<size_type>(T::size_),
0048                       "All strings (except size_) must be explicitly given");
0049     }
0050
0051     // Convert from a string
0052     inline char const* operator()(T value) const;
0053
0054   private:
0055     using size_type = std::underlying_type_t<T>;
0056
0057     Array<char const*, static_cast<size_type>(T::size_) + 1> const strings_;
0058 };
0059
0060 //---------------------------------------------------------------------------//
0061 // INLINE DEFINITIONS
0062 //---------------------------------------------------------------------------//
0063 /*!
0064  * Convert an enum to the corresponding string.
0065  */
0066 template<class T>
0067 char const* EnumStringMapper<T>::operator()(T value) const
0068 {
0069     CELER_EXPECT(value <= T::size_);
0070     return strings_[static_cast<size_type>(value)];
0071 }
0072
0073 //---------------------------------------------------------------------------//
0074 }  // namespace celeritas