pfr/detail/for_each_field_impl.hpp

0001 // Copyright (c) 2016-2025 Antony Polukhin
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 #ifndef BOOST_PFR_DETAIL_FOR_EACH_FIELD_IMPL_HPP
0007 #define BOOST_PFR_DETAIL_FOR_EACH_FIELD_IMPL_HPP
0008 #pragma once
0009
0010 #include <boost/pfr/detail/config.hpp>
0011
0012 #ifdef BOOST_PFR_HAS_STD_MODULE
0013 import std;
0014 #else
0015 #include <utility>      // metaprogramming stuff
0016 #endif
0017
0018 #include <boost/pfr/detail/sequence_tuple.hpp>
0019 #include <boost/pfr/detail/rvalue_t.hpp>
0020
0021 namespace boost { namespace pfr { namespace detail {
0022
0023 template <std::size_t Index>
0024 using size_t_ = std::integral_constant<std::size_t, Index >;
0025
0026 template <class T, class F, class I, class = decltype(std::declval<F>()(std::declval<T>(), I{}))>
0027 constexpr void for_each_field_impl_apply(T&& v, F&& f, I i, long) {
0028     std::forward<F>(f)(std::forward<T>(v), i);
0029 }
0030
0031 template <class T, class F, class I>
0032 constexpr void for_each_field_impl_apply(T&& v, F&& f, I /*i*/, int) {
0033     std::forward<F>(f)(std::forward<T>(v));
0034 }
0035
0036 #if !defined(__cpp_fold_expressions) || __cpp_fold_expressions < 201603
0037 template <class T, class F, std::size_t... I>
0038 constexpr void for_each_field_impl(T& t, F&& f, std::index_sequence<I...>, std::false_type /*move_values*/) {
0039      const int v[] = {0, (
0040          detail::for_each_field_impl_apply(sequence_tuple::get<I>(t), std::forward<F>(f), size_t_<I>{}, 1L),
0041          0
0042      )...};
0043      (void)v;
0044 }
0045
0046
0047 template <class T, class F, std::size_t... I>
0048 constexpr void for_each_field_impl(T& t, F&& f, std::index_sequence<I...>, std::true_type /*move_values*/) {
0049      const int v[] = {0, (
0050          detail::for_each_field_impl_apply(sequence_tuple::get<I>(std::move(t)), std::forward<F>(f), size_t_<I>{}, 1L),
0051          0
0052      )...};
0053      (void)v;
0054 }
0055 #else
0056 template <class T, class F, std::size_t... I>
0057 constexpr void for_each_field_impl(T& t, F&& f, std::index_sequence<I...>, std::false_type /*move_values*/) {
0058      (detail::for_each_field_impl_apply(sequence_tuple::get<I>(t), std::forward<F>(f), size_t_<I>{}, 1L), ...);
0059 }
0060
0061 template <class T, class F, std::size_t... I>
0062 constexpr void for_each_field_impl(T& t, F&& f, std::index_sequence<I...>, std::true_type /*move_values*/) {
0063      (detail::for_each_field_impl_apply(sequence_tuple::get<I>(std::move(t)), std::forward<F>(f), size_t_<I>{}, 1L), ...);
0064 }
0065 #endif
0066
0067 }}} // namespace boost::pfr::detail
0068
0069
0070 #endif // BOOST_PFR_DETAIL_FOR_EACH_FIELD_IMPL_HPP