84 lines
1.8 KiB
C++
84 lines
1.8 KiB
C++
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//
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// detail/utility.hpp
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// ~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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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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//
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#ifndef ASIO_DETAIL_UTILITY_HPP
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#define ASIO_DETAIL_UTILITY_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/config.hpp"
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#include <utility>
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namespace asio {
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namespace detail {
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#if defined(ASIO_HAS_STD_INDEX_SEQUENCE)
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using std::index_sequence;
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using std::index_sequence_for;
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using std::make_index_sequence;
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#elif defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <std::size_t...>
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struct index_sequence
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{
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};
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template <typename T, typename U>
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struct join_index_sequences;
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template <std::size_t... I, std::size_t... J>
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struct join_index_sequences<index_sequence<I...>, index_sequence<J...> >
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{
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using type = index_sequence<I..., J...>;
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};
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template <std::size_t First, std::size_t Last>
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struct index_pack :
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join_index_sequences<
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typename index_pack<First, First + (Last - First + 1) / 2 - 1>::type,
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typename index_pack<First + (Last - First + 1) / 2, Last>::type
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>
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{
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};
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template <std::size_t N>
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struct index_pack<N, N>
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{
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using type = index_sequence<N>;
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};
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template <std::size_t Begin, std::size_t End>
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struct index_range : index_pack<Begin, End - 1>
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{
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};
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template <std::size_t N>
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struct index_range<N, N>
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{
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using type = index_sequence<>;
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};
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template <typename... T>
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using index_sequence_for = typename index_range<0, sizeof...(T)>::type;
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template <std::size_t N>
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using make_index_sequence = typename index_range<0, N>::type;
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#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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} // namespace detail
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} // namespace asio
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#endif // ASIO_DETAIL_UTILITY_HPP
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