boost/pfr/core_name.hpp

0001 // Copyright (c) 2023 Bela Schaum, X-Ryl669, Denis Mikhailov.
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006
0007 // Initial implementation by Bela Schaum, https://github.com/schaumb
0008 // The way to make it union and UB free by X-Ryl669, https://github.com/X-Ryl669
0009 //
0010
0011 #ifndef BOOST_PFR_CORE_NAME_HPP
0012 #define BOOST_PFR_CORE_NAME_HPP
0013 #pragma once
0014
0015 #include <boost/pfr/detail/config.hpp>
0016
0017 #include <boost/pfr/detail/core_name.hpp>
0018
0019 #include <boost/pfr/detail/sequence_tuple.hpp>
0020 #include <boost/pfr/detail/stdarray.hpp>
0021 #include <boost/pfr/detail/make_integer_sequence.hpp>
0022
0023 #include <cstddef> // for std::size_t
0024
0025 #include <boost/pfr/tuple_size.hpp>
0026
0027 /// \file boost/pfr/core_name.hpp
0028 /// Contains functions \forcedlink{get_name} and \forcedlink{names_as_array} to know which names each field of any \aggregate has.
0029 ///
0030 /// \fnrefl for details.
0031 ///
0032 /// \b Synopsis:
0033
0034 namespace boost { namespace pfr {
0035
0036 /// \brief Returns name of a field with index `I` in \aggregate `T`.
0037 ///
0038 /// \b Example:
0039 /// \code
0040 ///     struct my_struct { int i, short s; };
0041 ///
0042 ///     assert(boost::pfr::get_name<0, my_struct>() == "i");
0043 ///     assert(boost::pfr::get_name<1, my_struct>() == "s");
0044 /// \endcode
0045 template <std::size_t I, class T>
0046 constexpr
0047 #ifdef BOOST_PFR_DOXYGEN_INVOKED
0048 std::string_view
0049 #else
0050 auto
0051 #endif
0052 get_name() noexcept {
0053     return detail::get_name<T, I>();
0054 }
0055
0056 // FIXME: implement this
0057 // template<class U, class T>
0058 // constexpr auto get_name() noexcept {
0059 //     return detail::sequence_tuple::get_by_type_impl<U>( detail::tie_as_names_tuple<T>() );
0060 // }
0061
0062 /// \brief Creates a `std::array` from names of fields of an \aggregate `T`.
0063 ///
0064 /// \b Example:
0065 /// \code
0066 ///     struct my_struct { int i, short s; };
0067 ///     std::array<std::string_view, 2> a = boost::pfr::names_as_array<my_struct>();
0068 ///     assert(a[0] == "i");
0069 /// \endcode
0070 template <class T>
0071 constexpr
0072 #ifdef BOOST_PFR_DOXYGEN_INVOKED
0073 std::array<std::string_view, boost::pfr::tuple_size_v<T>>
0074 #else
0075 auto
0076 #endif
0077 names_as_array() noexcept {
0078     return detail::make_stdarray_from_tietuple(
0079         detail::tie_as_names_tuple<T>(),
0080         detail::make_index_sequence< tuple_size_v<T> >(),
0081         1L
0082     );
0083 }
0084
0085 }} // namespace boost::pfr
0086
0087 #endif // BOOST_PFR_CORE_NAME_HPP
0088