164 lines
4.5 KiB
C++
164 lines
4.5 KiB
C++
//
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// impl/prepend.hpp
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// ~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2024 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_IMPL_PREPEND_HPP
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#define ASIO_IMPL_PREPEND_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 "asio/associator.hpp"
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#include "asio/async_result.hpp"
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#include "asio/detail/handler_cont_helpers.hpp"
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#include "asio/detail/type_traits.hpp"
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#include "asio/detail/utility.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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namespace detail {
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// Class to adapt a prepend_t as a completion handler.
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template <typename Handler, typename... Values>
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class prepend_handler
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{
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public:
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typedef void result_type;
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template <typename H>
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prepend_handler(H&& handler, std::tuple<Values...> values)
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: handler_(static_cast<H&&>(handler)),
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values_(static_cast<std::tuple<Values...>&&>(values))
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{
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}
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template <typename... Args>
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void operator()(Args&&... args)
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{
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this->invoke(
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index_sequence_for<Values...>{},
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static_cast<Args&&>(args)...);
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}
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template <std::size_t... I, typename... Args>
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void invoke(index_sequence<I...>, Args&&... args)
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{
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static_cast<Handler&&>(handler_)(
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static_cast<Values&&>(std::get<I>(values_))...,
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static_cast<Args&&>(args)...);
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}
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//private:
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Handler handler_;
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std::tuple<Values...> values_;
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};
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template <typename Handler>
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inline bool asio_handler_is_continuation(
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prepend_handler<Handler>* this_handler)
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{
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return asio_handler_cont_helpers::is_continuation(
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this_handler->handler_);
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}
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template <typename Signature, typename... Values>
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struct prepend_signature;
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template <typename R, typename... Args, typename... Values>
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struct prepend_signature<R(Args...), Values...>
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{
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typedef R type(Values..., decay_t<Args>...);
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};
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} // namespace detail
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#if !defined(GENERATING_DOCUMENTATION)
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template <typename CompletionToken, typename... Values, typename Signature>
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struct async_result<
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prepend_t<CompletionToken, Values...>, Signature>
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: async_result<CompletionToken,
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typename detail::prepend_signature<
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Signature, Values...>::type>
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{
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typedef typename detail::prepend_signature<
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Signature, Values...>::type signature;
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template <typename Initiation>
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struct init_wrapper
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{
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init_wrapper(Initiation init)
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: initiation_(static_cast<Initiation&&>(init))
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{
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}
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template <typename Handler, typename... Args>
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void operator()(Handler&& handler,
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std::tuple<Values...> values, Args&&... args)
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{
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static_cast<Initiation&&>(initiation_)(
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detail::prepend_handler<decay_t<Handler>, Values...>(
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static_cast<Handler&&>(handler),
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static_cast<std::tuple<Values...>&&>(values)),
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static_cast<Args&&>(args)...);
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}
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Initiation initiation_;
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};
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template <typename Initiation, typename RawCompletionToken, typename... Args>
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static auto initiate(Initiation&& initiation,
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RawCompletionToken&& token, Args&&... args)
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-> decltype(
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async_initiate<CompletionToken, signature>(
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declval<init_wrapper<decay_t<Initiation>>>(),
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token.token_,
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static_cast<std::tuple<Values...>&&>(token.values_),
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static_cast<Args&&>(args)...))
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{
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return async_initiate<CompletionToken, signature>(
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init_wrapper<decay_t<Initiation>>(
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static_cast<Initiation&&>(initiation)),
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token.token_,
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static_cast<std::tuple<Values...>&&>(token.values_),
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static_cast<Args&&>(args)...);
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}
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};
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template <template <typename, typename> class Associator,
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typename Handler, typename... Values, typename DefaultCandidate>
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struct associator<Associator,
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detail::prepend_handler<Handler, Values...>, DefaultCandidate>
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: Associator<Handler, DefaultCandidate>
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{
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static typename Associator<Handler, DefaultCandidate>::type get(
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const detail::prepend_handler<Handler, Values...>& h) noexcept
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{
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return Associator<Handler, DefaultCandidate>::get(h.handler_);
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}
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static auto get(const detail::prepend_handler<Handler, Values...>& h,
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const DefaultCandidate& c) noexcept
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-> decltype(Associator<Handler, DefaultCandidate>::get(h.handler_, c))
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{
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return Associator<Handler, DefaultCandidate>::get(h.handler_, c);
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}
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};
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#endif // !defined(GENERATING_DOCUMENTATION)
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_IMPL_PREPEND_HPP
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