//
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// execution/execute.hpp
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// ~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2020 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 BOOST_ASIO_EXECUTION_EXECUTE_HPP
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#define BOOST_ASIO_EXECUTION_EXECUTE_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 <boost/asio/detail/config.hpp>
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#include <boost/asio/detail/type_traits.hpp>
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#include <boost/asio/execution/detail/as_invocable.hpp>
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#include <boost/asio/execution/detail/as_receiver.hpp>
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#include <boost/asio/traits/execute_member.hpp>
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#include <boost/asio/traits/execute_free.hpp>
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#include <boost/asio/detail/push_options.hpp>
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#if defined(GENERATING_DOCUMENTATION)
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namespace boost {
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namespace asio {
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namespace execution {
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/// A customisation point that executes a function on an executor.
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/**
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* The name <tt>execution::execute</tt> denotes a customisation point object.
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*
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* For some subexpressions <tt>e</tt> and <tt>f</tt>, let <tt>E</tt> be a type
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* such that <tt>decltype((e))</tt> is <tt>E</tt> and let <tt>F</tt> be a type
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* such that <tt>decltype((f))</tt> is <tt>F</tt>. The expression
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* <tt>execution::execute(e, f)</tt> is ill-formed if <tt>F</tt> does not model
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* <tt>invocable</tt>, or if <tt>E</tt> does not model either <tt>executor</tt>
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* or <tt>sender</tt>. Otherwise, it is expression-equivalent to:
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*
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* @li <tt>e.execute(f)</tt>, if that expression is valid. If the function
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* selected does not execute the function object <tt>f</tt> on the executor
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* <tt>e</tt>, the program is ill-formed with no diagnostic required.
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*
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* @li Otherwise, <tt>execute(e, f)</tt>, if that expression is valid, with
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* overload resolution performed in a context that includes the declaration
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* <tt>void execute();</tt> and that does not include a declaration of
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* <tt>execution::execute</tt>. If the function selected by overload
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* resolution does not execute the function object <tt>f</tt> on the executor
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* <tt>e</tt>, the program is ill-formed with no diagnostic required.
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*/
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inline constexpr unspecified execute = unspecified;
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/// A type trait that determines whether a @c execute expression is well-formed.
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/**
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* Class template @c can_execute is a trait that is derived from
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* @c true_type if the expression <tt>execution::execute(std::declval<T>(),
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* std::declval<F>())</tt> is well formed; otherwise @c false_type.
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*/
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template <typename T, typename F>
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struct can_execute :
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integral_constant<bool, automatically_determined>
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{
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};
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} // namespace execution
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} // namespace asio
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} // namespace boost
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#else // defined(GENERATING_DOCUMENTATION)
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namespace boost {
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namespace asio {
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namespace execution {
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template <typename T, typename R>
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struct is_sender_to;
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namespace detail {
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template <typename S, typename R>
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void submit_helper(BOOST_ASIO_MOVE_ARG(S) s, BOOST_ASIO_MOVE_ARG(R) r);
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} // namespace detail
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} // namespace execution
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} // namespace asio
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} // namespace boost
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namespace asio_execution_execute_fn {
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using boost::asio::conditional;
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using boost::asio::decay;
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using boost::asio::declval;
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using boost::asio::enable_if;
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using boost::asio::execution::detail::as_receiver;
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using boost::asio::execution::detail::is_as_invocable;
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using boost::asio::execution::is_sender_to;
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using boost::asio::false_type;
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using boost::asio::result_of;
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using boost::asio::traits::execute_free;
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using boost::asio::traits::execute_member;
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using boost::asio::true_type;
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void execute();
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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 T, typename F, typename = void>
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struct call_traits
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{
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BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed);
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};
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template <typename T, typename F>
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struct call_traits<T, void(F),
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typename enable_if<
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(
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execute_member<T, F>::is_valid
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)
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>::type> :
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execute_member<T, F>
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{
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BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
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};
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template <typename T, typename F>
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struct call_traits<T, void(F),
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typename enable_if<
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(
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!execute_member<T, F>::is_valid
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&&
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execute_free<T, F>::is_valid
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)
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>::type> :
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execute_free<T, F>
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{
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BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
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};
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template <typename T, typename F>
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struct call_traits<T, void(F),
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typename enable_if<
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(
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!execute_member<T, F>::is_valid
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&&
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!execute_free<T, F>::is_valid
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&&
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conditional<true, true_type,
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typename result_of<typename decay<F>::type&()>::type
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>::type::value
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&&
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conditional<
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!is_as_invocable<
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typename decay<F>::type
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>::value,
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is_sender_to<
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T,
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as_receiver<typename decay<F>::type, T>
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>,
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false_type
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>::type::value
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)
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>::type>
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{
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BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = adapter);
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BOOST_ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
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BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
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typedef void result_type;
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};
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struct impl
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{
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template <typename T, typename F>
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BOOST_ASIO_CONSTEXPR typename enable_if<
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call_traits<T, void(F)>::overload == call_member,
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typename call_traits<T, void(F)>::result_type
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>::type
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operator()(
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BOOST_ASIO_MOVE_ARG(T) t,
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BOOST_ASIO_MOVE_ARG(F) f) const
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BOOST_ASIO_NOEXCEPT_IF((
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call_traits<T, void(F)>::is_noexcept))
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{
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return BOOST_ASIO_MOVE_CAST(T)(t).execute(BOOST_ASIO_MOVE_CAST(F)(f));
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}
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template <typename T, typename F>
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BOOST_ASIO_CONSTEXPR typename enable_if<
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call_traits<T, void(F)>::overload == call_free,
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typename call_traits<T, void(F)>::result_type
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>::type
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operator()(
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BOOST_ASIO_MOVE_ARG(T) t,
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BOOST_ASIO_MOVE_ARG(F) f) const
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BOOST_ASIO_NOEXCEPT_IF((
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call_traits<T, void(F)>::is_noexcept))
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{
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return execute(BOOST_ASIO_MOVE_CAST(T)(t), BOOST_ASIO_MOVE_CAST(F)(f));
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}
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template <typename T, typename F>
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BOOST_ASIO_CONSTEXPR typename enable_if<
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call_traits<T, void(F)>::overload == adapter,
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typename call_traits<T, void(F)>::result_type
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>::type
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operator()(
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BOOST_ASIO_MOVE_ARG(T) t,
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BOOST_ASIO_MOVE_ARG(F) f) const
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BOOST_ASIO_NOEXCEPT_IF((
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call_traits<T, void(F)>::is_noexcept))
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{
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return boost::asio::execution::detail::submit_helper(
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BOOST_ASIO_MOVE_CAST(T)(t),
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as_receiver<typename decay<F>::type, T>(
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BOOST_ASIO_MOVE_CAST(F)(f), 0));
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}
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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_execute_fn
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namespace boost {
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namespace asio {
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namespace execution {
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namespace {
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static BOOST_ASIO_CONSTEXPR const asio_execution_execute_fn::impl&
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execute = asio_execution_execute_fn::static_instance<>::instance;
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} // namespace
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template <typename T, typename F>
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struct can_execute :
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integral_constant<bool,
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asio_execution_execute_fn::call_traits<T, void(F)>::overload !=
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asio_execution_execute_fn::ill_formed>
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{
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};
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#if defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename T, typename F>
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constexpr bool can_execute_v = can_execute<T, F>::value;
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#endif // defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
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} // namespace execution
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} // namespace asio
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} // namespace boost
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#endif // defined(GENERATING_DOCUMENTATION)
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#include <boost/asio/detail/pop_options.hpp>
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#endif // BOOST_ASIO_EXECUTION_EXECUTE_HPP
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