490 lines
14 KiB
C++
490 lines
14 KiB
C++
//
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// execution/connect.hpp
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// ~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2021 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_EXECUTION_CONNECT_HPP
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#define ASIO_EXECUTION_CONNECT_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/detail/type_traits.hpp"
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#include "asio/execution/detail/as_invocable.hpp"
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#include "asio/execution/detail/as_operation.hpp"
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#include "asio/execution/detail/as_receiver.hpp"
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#include "asio/execution/executor.hpp"
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#include "asio/execution/operation_state.hpp"
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#include "asio/execution/receiver.hpp"
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#include "asio/execution/sender.hpp"
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#include "asio/traits/connect_member.hpp"
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#include "asio/traits/connect_free.hpp"
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#include "asio/detail/push_options.hpp"
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#if defined(GENERATING_DOCUMENTATION)
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namespace asio {
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namespace execution {
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/// A customisation point that connects a sender to a receiver.
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/**
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* The name <tt>execution::connect</tt> denotes a customisation point object.
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* For some subexpressions <tt>s</tt> and <tt>r</tt>, let <tt>S</tt> be a type
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* such that <tt>decltype((s))</tt> is <tt>S</tt> and let <tt>R</tt> be a type
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* such that <tt>decltype((r))</tt> is <tt>R</tt>. The expression
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* <tt>execution::connect(s, r)</tt> is expression-equivalent to:
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*
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* @li <tt>s.connect(r)</tt>, if that expression is valid, if its type
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* satisfies <tt>operation_state</tt>, and if <tt>S</tt> satisfies
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* <tt>sender</tt>.
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*
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* @li Otherwise, <tt>connect(s, r)</tt>, if that expression is valid, if its
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* type satisfies <tt>operation_state</tt>, and if <tt>S</tt> satisfies
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* <tt>sender</tt>, with overload resolution performed in a context that
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* includes the declaration <tt>void connect();</tt> and that does not include
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* a declaration of <tt>execution::connect</tt>.
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*
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* @li Otherwise, <tt>as_operation{s, r}</tt>, if <tt>r</tt> is not an instance
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* of <tt>as_receiver<F, S></tt> for some type <tt>F</tt>, and if
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* <tt>receiver_of<R> && executor_of<remove_cvref_t<S>,
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* as_invocable<remove_cvref_t<R>, S>></tt> is <tt>true</tt>, where
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* <tt>as_operation</tt> is an implementation-defined class equivalent to
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* @code template <class S, class R>
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* struct as_operation
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* {
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* remove_cvref_t<S> e_;
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* remove_cvref_t<R> r_;
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* void start() noexcept try {
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* execution::execute(std::move(e_),
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* as_invocable<remove_cvref_t<R>, S>{r_});
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* } catch(...) {
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* execution::set_error(std::move(r_), current_exception());
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* }
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* }; @endcode
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* and <tt>as_invocable</tt> is a class template equivalent to the following:
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* @code template<class R>
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* struct as_invocable
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* {
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* R* r_;
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* explicit as_invocable(R& r) noexcept
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* : r_(std::addressof(r)) {}
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* as_invocable(as_invocable && other) noexcept
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* : r_(std::exchange(other.r_, nullptr)) {}
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* ~as_invocable() {
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* if(r_)
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* execution::set_done(std::move(*r_));
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* }
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* void operator()() & noexcept try {
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* execution::set_value(std::move(*r_));
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* r_ = nullptr;
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* } catch(...) {
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* execution::set_error(std::move(*r_), current_exception());
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* r_ = nullptr;
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* }
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* };
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* @endcode
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*
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* @li Otherwise, <tt>execution::connect(s, r)</tt> is ill-formed.
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*/
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inline constexpr unspecified connect = unspecified;
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/// A type trait that determines whether a @c connect expression is
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/// well-formed.
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/**
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* Class template @c can_connect is a trait that is derived from
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* @c true_type if the expression <tt>execution::connect(std::declval<S>(),
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* std::declval<R>())</tt> is well formed; otherwise @c false_type.
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*/
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template <typename S, typename R>
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struct can_connect :
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integral_constant<bool, automatically_determined>
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{
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};
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/// A type trait to determine the result of a @c connect expression.
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template <typename S, typename R>
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struct connect_result
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{
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/// The type of the connect expression.
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/**
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* The type of the expression <tt>execution::connect(std::declval<S>(),
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* std::declval<R>())</tt>.
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*/
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typedef automatically_determined type;
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};
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/// A type alis to determine the result of a @c connect expression.
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template <typename S, typename R>
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using connect_result_t = typename connect_result<S, R>::type;
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} // namespace execution
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} // namespace asio
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#else // defined(GENERATING_DOCUMENTATION)
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namespace asio_execution_connect_fn {
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using asio::conditional;
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using asio::declval;
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using asio::enable_if;
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using asio::execution::detail::as_invocable;
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using asio::execution::detail::as_operation;
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using asio::execution::detail::is_as_receiver;
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using asio::execution::is_executor_of;
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using asio::execution::is_operation_state;
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using asio::execution::is_receiver;
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using asio::execution::is_sender;
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using asio::false_type;
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using asio::remove_cvref;
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using asio::traits::connect_free;
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using asio::traits::connect_member;
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void connect();
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enum overload_type
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{
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call_member,
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call_free,
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adapter,
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ill_formed
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};
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template <typename S, typename R, typename = void,
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typename = void, typename = void, typename = void>
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struct call_traits
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{
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ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed);
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ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
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typedef void result_type;
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};
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template <typename S, typename R>
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struct call_traits<S, void(R),
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typename enable_if<
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connect_member<S, R>::is_valid
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>::type,
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typename enable_if<
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is_operation_state<typename connect_member<S, R>::result_type>::value
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>::type,
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typename enable_if<
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is_sender<typename remove_cvref<S>::type>::value
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>::type> :
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connect_member<S, R>
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{
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ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
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};
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template <typename S, typename R>
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struct call_traits<S, void(R),
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typename enable_if<
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!connect_member<S, R>::is_valid
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>::type,
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typename enable_if<
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connect_free<S, R>::is_valid
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>::type,
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typename enable_if<
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is_operation_state<typename connect_free<S, R>::result_type>::value
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>::type,
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typename enable_if<
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is_sender<typename remove_cvref<S>::type>::value
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>::type> :
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connect_free<S, R>
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{
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ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
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};
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template <typename S, typename R>
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struct call_traits<S, void(R),
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typename enable_if<
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!connect_member<S, R>::is_valid
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>::type,
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typename enable_if<
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!connect_free<S, R>::is_valid
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>::type,
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typename enable_if<
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is_receiver<R>::value
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>::type,
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typename enable_if<
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conditional<
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!is_as_receiver<
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typename remove_cvref<R>::type
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>::value,
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is_executor_of<
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typename remove_cvref<S>::type,
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as_invocable<typename remove_cvref<R>::type, S>
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>,
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false_type
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>::type::value
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>::type>
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{
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ASIO_STATIC_CONSTEXPR(overload_type, overload = adapter);
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ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
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typedef as_operation<S, R> result_type;
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};
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struct impl
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{
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#if defined(ASIO_HAS_MOVE)
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S, void(R)>::overload == call_member,
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typename call_traits<S, void(R)>::result_type
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>::type
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operator()(S&& s, R&& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S, void(R)>::is_noexcept))
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{
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return ASIO_MOVE_CAST(S)(s).connect(ASIO_MOVE_CAST(R)(r));
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S, void(R)>::overload == call_free,
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typename call_traits<S, void(R)>::result_type
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>::type
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operator()(S&& s, R&& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S, void(R)>::is_noexcept))
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{
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return connect(ASIO_MOVE_CAST(S)(s), ASIO_MOVE_CAST(R)(r));
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S, void(R)>::overload == adapter,
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typename call_traits<S, void(R)>::result_type
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>::type
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operator()(S&& s, R&& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S, void(R)>::is_noexcept))
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{
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return typename call_traits<S, void(R)>::result_type(
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ASIO_MOVE_CAST(S)(s), ASIO_MOVE_CAST(R)(r));
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}
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#else // defined(ASIO_HAS_MOVE)
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(R&)>::overload == call_member,
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typename call_traits<S&, void(R&)>::result_type
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>::type
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operator()(S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(R&)>::is_noexcept))
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{
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return s.connect(r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(R&)>::overload == call_member,
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typename call_traits<const S&, void(R&)>::result_type
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>::type
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operator()(const S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(R&)>::is_noexcept))
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{
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return s.connect(r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(R&)>::overload == call_free,
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typename call_traits<S&, void(R&)>::result_type
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>::type
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operator()(S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(R&)>::is_noexcept))
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{
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return connect(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(R&)>::overload == call_free,
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typename call_traits<const S&, void(R&)>::result_type
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>::type
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operator()(const S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(R&)>::is_noexcept))
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{
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return connect(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(R&)>::overload == adapter,
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typename call_traits<S&, void(R&)>::result_type
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>::type
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operator()(S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(R&)>::is_noexcept))
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{
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return typename call_traits<S&, void(R&)>::result_type(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(R&)>::overload == adapter,
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typename call_traits<const S&, void(R&)>::result_type
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>::type
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operator()(const S& s, R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(R&)>::is_noexcept))
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{
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return typename call_traits<const S&, void(R&)>::result_type(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(const R&)>::overload == call_member,
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typename call_traits<S&, void(const R&)>::result_type
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>::type
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operator()(S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(const R&)>::is_noexcept))
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{
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return s.connect(r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(const R&)>::overload == call_member,
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typename call_traits<const S&, void(const R&)>::result_type
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>::type
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operator()(const S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(const R&)>::is_noexcept))
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{
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return s.connect(r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(const R&)>::overload == call_free,
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typename call_traits<S&, void(const R&)>::result_type
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>::type
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operator()(S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(const R&)>::is_noexcept))
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{
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return connect(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(const R&)>::overload == call_free,
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typename call_traits<const S&, void(const R&)>::result_type
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>::type
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operator()(const S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(const R&)>::is_noexcept))
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{
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return connect(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<S&, void(const R&)>::overload == adapter,
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typename call_traits<S&, void(const R&)>::result_type
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>::type
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operator()(S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<S&, void(const R&)>::is_noexcept))
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{
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return typename call_traits<S&, void(const R&)>::result_type(s, r);
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}
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template <typename S, typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const S&, void(const R&)>::overload == adapter,
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typename call_traits<const S&, void(const R&)>::result_type
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>::type
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operator()(const S& s, const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const S&, void(const R&)>::is_noexcept))
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{
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return typename call_traits<const S&, void(const R&)>::result_type(s, r);
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}
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#endif // defined(ASIO_HAS_MOVE)
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};
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template <typename T = impl>
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struct static_instance
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{
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static const T instance;
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};
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template <typename T>
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const T static_instance<T>::instance = {};
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} // namespace asio_execution_connect_fn
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namespace asio {
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namespace execution {
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namespace {
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static ASIO_CONSTEXPR const asio_execution_connect_fn::impl&
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connect = asio_execution_connect_fn::static_instance<>::instance;
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} // namespace
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template <typename S, typename R>
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struct can_connect :
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integral_constant<bool,
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asio_execution_connect_fn::call_traits<S, void(R)>::overload !=
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asio_execution_connect_fn::ill_formed>
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{
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};
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#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename S, typename R>
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constexpr bool can_connect_v = can_connect<S, R>::value;
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#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename S, typename R>
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struct is_nothrow_connect :
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integral_constant<bool,
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asio_execution_connect_fn::call_traits<S, void(R)>::is_noexcept>
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{
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};
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#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename S, typename R>
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constexpr bool is_nothrow_connect_v
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= is_nothrow_connect<S, R>::value;
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#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename S, typename R>
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struct connect_result
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{
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typedef typename asio_execution_connect_fn::call_traits<
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S, void(R)>::result_type type;
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};
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#if defined(ASIO_HAS_ALIAS_TEMPLATES)
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template <typename S, typename R>
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using connect_result_t = typename connect_result<S, R>::type;
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#endif // defined(ASIO_HAS_ALIAS_TEMPLATES)
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} // namespace execution
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} // namespace asio
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#endif // defined(GENERATING_DOCUMENTATION)
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_EXECUTION_CONNECT_HPP
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