484 lines
14 KiB
C++
484 lines
14 KiB
C++
//
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// execution/set_value.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_SET_VALUE_HPP
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#define ASIO_EXECUTION_SET_VALUE_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/detail/variadic_templates.hpp"
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#include "asio/traits/set_value_member.hpp"
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#include "asio/traits/set_value_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 delivers a value to a receiver.
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/**
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* The name <tt>execution::set_value</tt> denotes a customisation point object.
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* The expression <tt>execution::set_value(R, Vs...)</tt> for some
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* subexpressions <tt>R</tt> and <tt>Vs...</tt> is expression-equivalent to:
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*
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* @li <tt>R.set_value(Vs...)</tt>, if that expression is valid. If the
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* function selected does not send the value(s) <tt>Vs...</tt> to the receiver
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* <tt>R</tt>'s value channel, the program is ill-formed with no diagnostic
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* required.
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*
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* @li Otherwise, <tt>set_value(R, Vs...)</tt>, if that expression is valid,
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* with overload resolution performed in a context that includes the
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* declaration <tt>void set_value();</tt> and that does not include a
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* declaration of <tt>execution::set_value</tt>. If the function selected by
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* overload resolution does not send the value(s) <tt>Vs...</tt> to the
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* receiver <tt>R</tt>'s value channel, the program is ill-formed with no
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* diagnostic required.
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*
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* @li Otherwise, <tt>execution::set_value(R, Vs...)</tt> is ill-formed.
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*/
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inline constexpr unspecified set_value = unspecified;
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/// A type trait that determines whether a @c set_value expression is
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/// well-formed.
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/**
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* Class template @c can_set_value is a trait that is derived from
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* @c true_type if the expression <tt>execution::set_value(std::declval<R>(),
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* std::declval<Vs>()...)</tt> is well formed; otherwise @c false_type.
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*/
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template <typename R, typename... Vs>
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struct can_set_value :
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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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#else // defined(GENERATING_DOCUMENTATION)
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namespace asio_execution_set_value_fn {
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using asio::decay;
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using asio::declval;
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using asio::enable_if;
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using asio::traits::set_value_free;
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using asio::traits::set_value_member;
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void set_value();
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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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ill_formed
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};
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template <typename R, typename Vs, 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 R, typename Vs>
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struct call_traits<R, Vs,
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typename enable_if<
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set_value_member<R, Vs>::is_valid
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>::type> :
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set_value_member<R, Vs>
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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 R, typename Vs>
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struct call_traits<R, Vs,
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typename enable_if<
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!set_value_member<R, Vs>::is_valid
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>::type,
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typename enable_if<
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set_value_free<R, Vs>::is_valid
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>::type> :
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set_value_free<R, Vs>
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{
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ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
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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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#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void(Vs...)>::overload == call_member,
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typename call_traits<R, void(Vs...)>::result_type
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>::type
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operator()(R&& r, Vs&&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void(Vs...)>::is_noexcept))
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{
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return ASIO_MOVE_CAST(R)(r).set_value(ASIO_MOVE_CAST(Vs)(v)...);
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}
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void(Vs...)>::overload == call_free,
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typename call_traits<R, void(Vs...)>::result_type
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>::type
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operator()(R&& r, Vs&&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void(Vs...)>::is_noexcept))
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{
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return set_value(ASIO_MOVE_CAST(R)(r),
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ASIO_MOVE_CAST(Vs)(v)...);
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}
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#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void()>::overload == call_member,
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typename call_traits<R, void()>::result_type
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>::type
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operator()(R&& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void()>::is_noexcept))
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{
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return ASIO_MOVE_CAST(R)(r).set_value();
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}
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void()>::overload == call_free,
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typename call_traits<R, void()>::result_type
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>::type
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operator()(R&& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void()>::is_noexcept))
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{
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return set_value(ASIO_MOVE_CAST(R)(r));
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}
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#define ASIO_PRIVATE_SET_VALUE_CALL_DEF(n) \
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<R, \
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void(ASIO_VARIADIC_TARGS(n))>::overload == call_member, \
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typename call_traits<R, void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(R&& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<R, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return ASIO_MOVE_CAST(R)(r).set_value( \
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ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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\
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<R, void(ASIO_VARIADIC_TARGS(n))>::overload == call_free, \
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typename call_traits<R, void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(R&& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<R, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return set_value(ASIO_MOVE_CAST(R)(r), \
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ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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/**/
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ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_SET_VALUE_CALL_DEF)
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#undef ASIO_PRIVATE_SET_VALUE_CALL_DEF
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#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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#else // defined(ASIO_HAS_MOVE)
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#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void(const Vs&...)>::overload == call_member,
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typename call_traits<R&, void(const Vs&...)>::result_type
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>::type
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operator()(R& r, const Vs&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void(const Vs&...)>::is_noexcept))
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{
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return r.set_value(v...);
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}
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void(const Vs&...)>::overload == call_member,
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typename call_traits<const R&, void(const Vs&...)>::result_type
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>::type
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operator()(const R& r, const Vs&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void(const Vs&...)>::is_noexcept))
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{
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return r.set_value(v...);
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}
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void(const Vs&...)>::overload == call_free,
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typename call_traits<R&, void(const Vs&...)>::result_type
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>::type
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operator()(R& r, const Vs&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void(const Vs&...)>::is_noexcept))
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{
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return set_value(r, v...);
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}
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template <typename R, typename... Vs>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void(const Vs&...)>::overload == call_free,
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typename call_traits<const R&, void(const Vs&...)>::result_type
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>::type
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operator()(const R& r, const Vs&... v) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void(const Vs&...)>::is_noexcept))
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{
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return set_value(r, v...);
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}
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#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void()>::overload == call_member,
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typename call_traits<R&, void()>::result_type
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>::type
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operator()(R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void()>::is_noexcept))
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{
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return r.set_value();
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}
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void()>::overload == call_member,
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typename call_traits<const R&, void()>::result_type
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>::type
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operator()(const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void()>::is_noexcept))
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{
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return r.set_value();
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}
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void()>::overload == call_free,
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typename call_traits<R&, void()>::result_type
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>::type
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operator()(R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void()>::is_noexcept))
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{
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return set_value(r);
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}
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template <typename R>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void()>::overload == call_free,
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typename call_traits<const R&, void()>::result_type
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>::type
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operator()(const R& r) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void()>::is_noexcept))
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{
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return set_value(r);
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}
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#define ASIO_PRIVATE_SET_VALUE_CALL_DEF(n) \
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<R&, \
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void(ASIO_VARIADIC_TARGS(n))>::overload == call_member, \
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typename call_traits<R&, void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(R& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<R&, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return r.set_value(ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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\
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<const R&, \
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void(ASIO_VARIADIC_TARGS(n))>::overload == call_member, \
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typename call_traits<const R&, \
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void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(const R& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<const R&, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return r.set_value(ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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\
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<R&, \
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void(ASIO_VARIADIC_TARGS(n))>::overload == call_free, \
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typename call_traits<R&, void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(R& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<R&, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return set_value(r, ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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\
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_CONSTEXPR typename enable_if< \
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call_traits<const R&, \
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void(ASIO_VARIADIC_TARGS(n))>::overload == call_free, \
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typename call_traits<const R&, \
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void(ASIO_VARIADIC_TARGS(n))>::result_type \
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>::type \
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operator()(const R& r, ASIO_VARIADIC_MOVE_PARAMS(n)) const \
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ASIO_NOEXCEPT_IF(( \
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call_traits<const R&, void(ASIO_VARIADIC_TARGS(n))>::is_noexcept)) \
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{ \
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return set_value(r, ASIO_VARIADIC_MOVE_ARGS(n)); \
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} \
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/**/
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ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_SET_VALUE_CALL_DEF)
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#undef ASIO_PRIVATE_SET_VALUE_CALL_DEF
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#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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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_set_value_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_set_value_fn::impl&
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set_value = asio_execution_set_value_fn::static_instance<>::instance;
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} // namespace
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#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R, typename... Vs>
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struct can_set_value :
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integral_constant<bool,
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asio_execution_set_value_fn::call_traits<R, void(Vs...)>::overload !=
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asio_execution_set_value_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 R, typename... Vs>
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constexpr bool can_set_value_v = can_set_value<R, Vs...>::value;
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#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename R, typename... Vs>
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struct is_nothrow_set_value :
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integral_constant<bool,
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asio_execution_set_value_fn::call_traits<R, void(Vs...)>::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 R, typename... Vs>
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constexpr bool is_nothrow_set_value_v
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= is_nothrow_set_value<R, Vs...>::value;
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#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
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#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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template <typename R, typename = void,
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typename = void, typename = void, typename = void, typename = void,
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typename = void, typename = void, typename = void, typename = void>
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struct can_set_value;
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template <typename R, typename = void,
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typename = void, typename = void, typename = void, typename = void,
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typename = void, typename = void, typename = void, typename = void>
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struct is_nothrow_set_value;
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template <typename R>
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struct can_set_value<R> :
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integral_constant<bool,
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asio_execution_set_value_fn::call_traits<R, void()>::overload !=
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asio_execution_set_value_fn::ill_formed>
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{
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};
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template <typename R>
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struct is_nothrow_set_value<R> :
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integral_constant<bool,
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asio_execution_set_value_fn::call_traits<R, void()>::is_noexcept>
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{
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};
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#define ASIO_PRIVATE_SET_VALUE_TRAITS_DEF(n) \
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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struct can_set_value<R, ASIO_VARIADIC_TARGS(n)> : \
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integral_constant<bool, \
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asio_execution_set_value_fn::call_traits<R, \
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void(ASIO_VARIADIC_TARGS(n))>::overload != \
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asio_execution_set_value_fn::ill_formed> \
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{ \
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}; \
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\
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template <typename R, ASIO_VARIADIC_TPARAMS(n)> \
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struct is_nothrow_set_value<R, ASIO_VARIADIC_TARGS(n)> : \
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integral_constant<bool, \
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asio_execution_set_value_fn::call_traits<R, \
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void(ASIO_VARIADIC_TARGS(n))>::is_noexcept> \
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{ \
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}; \
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/**/
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ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_SET_VALUE_TRAITS_DEF)
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#undef ASIO_PRIVATE_SET_VALUE_TRAITS_DEF
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#endif // defined(ASIO_HAS_VARIADIC_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_SET_VALUE_HPP
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