// Copyright (c) 2016-2020 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_SEQUENCE_TUPLE_HPP
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#define BOOST_PFR_DETAIL_SEQUENCE_TUPLE_HPP
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#pragma once
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#include <boost/pfr/detail/config.hpp>
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#include <boost/pfr/detail/make_integer_sequence.hpp>
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#include <utility> // metaprogramming stuff
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#include <cstddef> // std::size_t
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///////////////////// Tuple that holds its values in the supplied order
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namespace boost { namespace pfr { namespace detail { namespace sequence_tuple {
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template <std::size_t N, class T>
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struct base_from_member {
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T value;
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};
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template <class I, class ...Tail>
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struct tuple_base;
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template <std::size_t... I, class ...Tail>
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struct tuple_base< std::index_sequence<I...>, Tail... >
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: base_from_member<I , Tail>...
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{
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static constexpr std::size_t size_v = sizeof...(I);
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// We do not use `noexcept` in the following functions, because if user forget to put one then clang will issue an error:
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// "error: exception specification of explicitly defaulted default constructor does not match the calculated one".
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constexpr tuple_base() = default;
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constexpr tuple_base(tuple_base&&) = default;
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constexpr tuple_base(const tuple_base&) = default;
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constexpr tuple_base(Tail... v) noexcept
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: base_from_member<I, Tail>{ v }...
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{}
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};
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template <>
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struct tuple_base<std::index_sequence<> > {
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static constexpr std::size_t size_v = 0;
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};
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template <std::size_t N, class T>
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constexpr T& get_impl(base_from_member<N, T>& t) noexcept {
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return t.value;
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}
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template <std::size_t N, class T>
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constexpr const T& get_impl(const base_from_member<N, T>& t) noexcept {
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return t.value;
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}
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template <std::size_t N, class T>
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constexpr volatile T& get_impl(volatile base_from_member<N, T>& t) noexcept {
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return t.value;
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}
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template <std::size_t N, class T>
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constexpr const volatile T& get_impl(const volatile base_from_member<N, T>& t) noexcept {
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return t.value;
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}
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template <std::size_t N, class T>
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constexpr T&& get_impl(base_from_member<N, T>&& t) noexcept {
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return std::forward<T>(t.value);
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}
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template <class ...Values>
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struct tuple: tuple_base<
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detail::index_sequence_for<Values...>,
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Values...>
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{
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using tuple_base<
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detail::index_sequence_for<Values...>,
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Values...
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>::tuple_base;
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};
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template <std::size_t N, class ...T>
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constexpr decltype(auto) get(tuple<T...>& t) noexcept {
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static_assert(N < tuple<T...>::size_v, "====================> Boost.PFR: Tuple index out of bounds");
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return sequence_tuple::get_impl<N>(t);
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}
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template <std::size_t N, class ...T>
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constexpr decltype(auto) get(const tuple<T...>& t) noexcept {
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static_assert(N < tuple<T...>::size_v, "====================> Boost.PFR: Tuple index out of bounds");
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return sequence_tuple::get_impl<N>(t);
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}
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template <std::size_t N, class ...T>
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constexpr decltype(auto) get(const volatile tuple<T...>& t) noexcept {
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static_assert(N < tuple<T...>::size_v, "====================> Boost.PFR: Tuple index out of bounds");
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return sequence_tuple::get_impl<N>(t);
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}
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template <std::size_t N, class ...T>
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constexpr decltype(auto) get(volatile tuple<T...>& t) noexcept {
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static_assert(N < tuple<T...>::size_v, "====================> Boost.PFR: Tuple index out of bounds");
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return sequence_tuple::get_impl<N>(t);
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}
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template <std::size_t N, class ...T>
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constexpr decltype(auto) get(tuple<T...>&& t) noexcept {
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static_assert(N < tuple<T...>::size_v, "====================> Boost.PFR: Tuple index out of bounds");
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return sequence_tuple::get_impl<N>(std::move(t));
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}
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template <std::size_t I, class T>
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using tuple_element = std::remove_reference< decltype(
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::boost::pfr::detail::sequence_tuple::get<I>( std::declval<T>() )
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) >;
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}}}} // namespace boost::pfr::detail::sequence_tuple
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#endif // BOOST_PFR_CORE_HPP
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