72 lines
2.6 KiB
C++
72 lines
2.6 KiB
C++
// Copyright (c) 2016-2022 Antony Polukhin
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_PFR_DETAIL_CORE17_HPP
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#define BOOST_PFR_DETAIL_CORE17_HPP
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#include <boost/pfr/detail/core17_generated.hpp>
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#include <boost/pfr/detail/fields_count.hpp>
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#include <boost/pfr/detail/for_each_field_impl.hpp>
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#include <boost/pfr/detail/rvalue_t.hpp>
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namespace boost { namespace pfr { namespace detail {
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#ifndef _MSC_VER // MSVC fails to compile the following code, but compiles the structured bindings in core17_generated.hpp
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struct do_not_define_std_tuple_size_for_me {
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bool test1 = true;
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};
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template <class T>
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constexpr bool do_structured_bindings_work() noexcept { // ******************************************* IN CASE OF ERROR READ THE FOLLOWING LINES IN boost/pfr/detail/core17.hpp FILE:
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T val{};
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const auto& [a] = val; // ******************************************* IN CASE OF ERROR READ THE FOLLOWING LINES IN boost/pfr/detail/core17.hpp FILE:
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/****************************************************************************
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*
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* It looks like your compiler or Standard Library can not handle C++17
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* structured bindings.
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*
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* Workaround: Define BOOST_PFR_USE_CPP17 to 0
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* It will disable the C++17 features for Boost.PFR library.
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*
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* Sorry for the inconvenience caused.
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*
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****************************************************************************/
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return a;
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}
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static_assert(
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do_structured_bindings_work<do_not_define_std_tuple_size_for_me>(),
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"====================> Boost.PFR: Your compiler can not handle C++17 structured bindings. Read the above comments for workarounds."
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);
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#endif // #ifndef _MSC_VER
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template <class T>
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constexpr auto tie_as_tuple(T& val) noexcept {
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static_assert(
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!std::is_union<T>::value,
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"====================> Boost.PFR: For safety reasons it is forbidden to reflect unions. See `Reflection of unions` section in the docs for more info."
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);
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typedef size_t_<boost::pfr::detail::fields_count<T>()> fields_count_tag;
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return boost::pfr::detail::tie_as_tuple(val, fields_count_tag{});
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}
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template <class T, class F, std::size_t... I>
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void for_each_field_dispatcher(T& t, F&& f, std::index_sequence<I...>) {
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static_assert(
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!std::is_union<T>::value,
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"====================> Boost.PFR: For safety reasons it is forbidden to reflect unions. See `Reflection of unions` section in the docs for more info."
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);
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std::forward<F>(f)(
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detail::tie_as_tuple(t)
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);
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}
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}}} // namespace boost::pfr::detail
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#endif // BOOST_PFR_DETAIL_CORE17_HPP
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