256 lines
7.0 KiB
C++
256 lines
7.0 KiB
C++
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//
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// execution/set_error.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_EXECUTION_SET_ERROR_HPP
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#define ASIO_EXECUTION_SET_ERROR_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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#if !defined(ASIO_NO_DEPRECATED)
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#include "asio/detail/type_traits.hpp"
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#include "asio/traits/set_error_member.hpp"
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#include "asio/traits/set_error_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 an error notification to a receiver.
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/**
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* The name <tt>execution::set_error</tt> denotes a customisation point object.
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* The expression <tt>execution::set_error(R, E)</tt> for some subexpressions
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* <tt>R</tt> and <tt>E</tt> are expression-equivalent to:
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*
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* @li <tt>R.set_error(E)</tt>, if that expression is valid. If the function
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* selected does not send the error <tt>E</tt> to the receiver <tt>R</tt>'s
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* error channel, the program is ill-formed with no diagnostic required.
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*
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* @li Otherwise, <tt>set_error(R, E)</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 set_error();</tt> and that does not include a declaration of
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* <tt>execution::set_error</tt>. If the function selected by overload
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* resolution does not send the error <tt>E</tt> to the receiver <tt>R</tt>'s
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* error channel, the program is ill-formed with no diagnostic required.
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*
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* @li Otherwise, <tt>execution::set_error(R, E)</tt> is ill-formed.
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*/
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inline constexpr unspecified set_error = unspecified;
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/// A type trait that determines whether a @c set_error expression is
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/// well-formed.
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/**
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* Class template @c can_set_error is a trait that is derived from
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* @c true_type if the expression <tt>execution::set_error(std::declval<R>(),
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* std::declval<E>())</tt> is well formed; otherwise @c false_type.
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*/
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template <typename R, typename E>
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struct can_set_error :
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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_error_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_error_free;
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using asio::traits::set_error_member;
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void set_error();
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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 E, 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 E>
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struct call_traits<R, void(E),
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typename enable_if<
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set_error_member<R, E>::is_valid
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>::type> :
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set_error_member<R, E>
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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 E>
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struct call_traits<R, void(E),
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typename enable_if<
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!set_error_member<R, E>::is_valid
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>::type,
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typename enable_if<
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set_error_free<R, E>::is_valid
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>::type> :
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set_error_free<R, E>
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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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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void(E)>::overload == call_member,
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typename call_traits<R, void(E)>::result_type
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>::type
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operator()(R&& r, E&& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void(E)>::is_noexcept))
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{
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return ASIO_MOVE_CAST(R)(r).set_error(ASIO_MOVE_CAST(E)(e));
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}
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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R, void(E)>::overload == call_free,
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typename call_traits<R, void(E)>::result_type
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>::type
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operator()(R&& r, E&& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<R, void(E)>::is_noexcept))
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{
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return set_error(ASIO_MOVE_CAST(R)(r), ASIO_MOVE_CAST(E)(e));
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}
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#else // defined(ASIO_HAS_MOVE)
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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void(const E&)>::overload == call_member,
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typename call_traits<R&, void(const E&)>::result_type
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>::type
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operator()(R& r, const E& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void(const E&)>::is_noexcept))
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{
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return r.set_error(e);
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}
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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void(const E&)>::overload == call_member,
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typename call_traits<const R&, void(const E&)>::result_type
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>::type
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operator()(const R& r, const E& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void(const E&)>::is_noexcept))
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{
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return r.set_error(e);
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}
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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<R&, void(const E&)>::overload == call_free,
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typename call_traits<R&, void(const E&)>::result_type
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>::type
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operator()(R& r, const E& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<R&, void(const E&)>::is_noexcept))
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{
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return set_error(r, e);
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}
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template <typename R, typename E>
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ASIO_CONSTEXPR typename enable_if<
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call_traits<const R&, void(const E&)>::overload == call_free,
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typename call_traits<const R&, void(const E&)>::result_type
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>::type
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operator()(const R& r, const E& e) const
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ASIO_NOEXCEPT_IF((
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call_traits<const R&, void(const E&)>::is_noexcept))
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{
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return set_error(r, e);
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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_set_error_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_error_fn::impl&
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set_error = asio_execution_set_error_fn::static_instance<>::instance;
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} // namespace
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template <typename R, typename E>
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struct can_set_error :
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integral_constant<bool,
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asio_execution_set_error_fn::call_traits<R, void(E)>::overload !=
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asio_execution_set_error_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 E>
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constexpr bool can_set_error_v = can_set_error<R, E>::value;
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#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
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template <typename R, typename E>
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struct is_nothrow_set_error :
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integral_constant<bool,
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asio_execution_set_error_fn::call_traits<R, void(E)>::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 E>
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constexpr bool is_nothrow_set_error_v
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= is_nothrow_set_error<R, E>::value;
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#endif // defined(ASIO_HAS_VARIABLE_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 // !defined(ASIO_NO_DEPRECATED)
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#endif // ASIO_EXECUTION_SET_ERROR_HPP
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