--- /dev/null
+//
+// execution/schedule.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_EXECUTION_SCHEDULE_HPP
+#define BOOST_ASIO_EXECUTION_SCHEDULE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution/executor.hpp>
+#include <boost/asio/traits/schedule_member.hpp>
+#include <boost/asio/traits/schedule_free.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+#if defined(GENERATING_DOCUMENTATION)
+
+namespace boost {
+namespace asio {
+namespace execution {
+
+/// A customisation point that is used to obtain a sender from a scheduler.
+/**
+ * The name <tt>execution::schedule</tt> denotes a customisation point object.
+ * For some subexpression <tt>s</tt>, let <tt>S</tt> be a type such that
+ * <tt>decltype((s))</tt> is <tt>S</tt>. The expression
+ * <tt>execution::schedule(s)</tt> is expression-equivalent to:
+ *
+ * @li <tt>s.schedule()</tt>, if that expression is valid and its type models
+ * <tt>sender</tt>.
+ *
+ * @li Otherwise, <tt>schedule(s)</tt>, if that expression is valid and its
+ * type models <tt>sender</tt> with overload resolution performed in a context
+ * that includes the declaration <tt>void schedule();</tt> and that does not
+ * include a declaration of <tt>execution::schedule</tt>.
+ *
+ * @li Otherwise, <tt>S</tt> if <tt>S</tt> satisfies <tt>executor</tt>.
+ *
+ * @li Otherwise, <tt>execution::schedule(s)</tt> is ill-formed.
+ */
+inline constexpr unspecified schedule = unspecified;
+
+/// A type trait that determines whether a @c schedule expression is
+/// well-formed.
+/**
+ * Class template @c can_schedule is a trait that is derived from @c true_type
+ * if the expression <tt>execution::schedule(std::declval<S>())</tt> is well
+ * formed; otherwise @c false_type.
+ */
+template <typename S>
+struct can_schedule :
+ integral_constant<bool, automatically_determined>
+{
+};
+
+} // namespace execution
+} // namespace asio
+} // namespace boost
+
+#else // defined(GENERATING_DOCUMENTATION)
+
+namespace asio_execution_schedule_fn {
+
+using boost::asio::decay;
+using boost::asio::declval;
+using boost::asio::enable_if;
+using boost::asio::execution::is_executor;
+using boost::asio::traits::schedule_free;
+using boost::asio::traits::schedule_member;
+
+void schedule();
+
+enum overload_type
+{
+ identity,
+ call_member,
+ call_free,
+ ill_formed
+};
+
+template <typename S, typename = void>
+struct call_traits
+{
+ BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed);
+ BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
+ typedef void result_type;
+};
+
+template <typename S>
+struct call_traits<S,
+ typename enable_if<
+ (
+ schedule_member<S>::is_valid
+ )
+ >::type> :
+ schedule_member<S>
+{
+ BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
+};
+
+template <typename S>
+struct call_traits<S,
+ typename enable_if<
+ (
+ !schedule_member<S>::is_valid
+ &&
+ schedule_free<S>::is_valid
+ )
+ >::type> :
+ schedule_free<S>
+{
+ BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
+};
+
+template <typename S>
+struct call_traits<S,
+ typename enable_if<
+ (
+ !schedule_member<S>::is_valid
+ &&
+ !schedule_free<S>::is_valid
+ &&
+ is_executor<typename decay<S>::type>::value
+ )
+ >::type>
+{
+ BOOST_ASIO_STATIC_CONSTEXPR(overload_type, overload = identity);
+ BOOST_ASIO_STATIC_CONSTEXPR(bool, is_noexcept = true);
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+ typedef BOOST_ASIO_MOVE_ARG(S) result_type;
+#else // defined(BOOST_ASIO_HAS_MOVE)
+ typedef BOOST_ASIO_MOVE_ARG(typename decay<S>::type) result_type;
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+struct impl
+{
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<S>::overload == identity,
+ typename call_traits<S>::result_type
+ >::type
+ operator()(BOOST_ASIO_MOVE_ARG(S) s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<S>::is_noexcept))
+ {
+ return BOOST_ASIO_MOVE_CAST(S)(s);
+ }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<S>::overload == call_member,
+ typename call_traits<S>::result_type
+ >::type
+ operator()(S&& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<S>::is_noexcept))
+ {
+ return BOOST_ASIO_MOVE_CAST(S)(s).schedule();
+ }
+
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<S>::overload == call_free,
+ typename call_traits<S>::result_type
+ >::type
+ operator()(S&& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<S>::is_noexcept))
+ {
+ return schedule(BOOST_ASIO_MOVE_CAST(S)(s));
+ }
+#else // defined(BOOST_ASIO_HAS_MOVE)
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<S&>::overload == call_member,
+ typename call_traits<S&>::result_type
+ >::type
+ operator()(S& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<S&>::is_noexcept))
+ {
+ return s.schedule();
+ }
+
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<const S&>::overload == call_member,
+ typename call_traits<const S&>::result_type
+ >::type
+ operator()(const S& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<const S&>::is_noexcept))
+ {
+ return s.schedule();
+ }
+
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<S&>::overload == call_free,
+ typename call_traits<S&>::result_type
+ >::type
+ operator()(S& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<S&>::is_noexcept))
+ {
+ return schedule(s);
+ }
+
+ template <typename S>
+ BOOST_ASIO_CONSTEXPR typename enable_if<
+ call_traits<const S&>::overload == call_free,
+ typename call_traits<const S&>::result_type
+ >::type
+ operator()(const S& s) const
+ BOOST_ASIO_NOEXCEPT_IF((
+ call_traits<const S&>::is_noexcept))
+ {
+ return schedule(s);
+ }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+template <typename T = impl>
+struct static_instance
+{
+ static const T instance;
+};
+
+template <typename T>
+const T static_instance<T>::instance = {};
+
+} // namespace asio_execution_schedule_fn
+namespace boost {
+namespace asio {
+namespace execution {
+namespace {
+
+static BOOST_ASIO_CONSTEXPR const asio_execution_schedule_fn::impl&
+ schedule = asio_execution_schedule_fn::static_instance<>::instance;
+
+} // namespace
+
+template <typename S>
+struct can_schedule :
+ integral_constant<bool,
+ asio_execution_schedule_fn::call_traits<S>::overload !=
+ asio_execution_schedule_fn::ill_formed>
+{
+};
+
+#if defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
+
+template <typename S>
+constexpr bool can_schedule_v = can_schedule<S>::value;
+
+#endif // defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
+
+template <typename S>
+struct is_nothrow_schedule :
+ integral_constant<bool,
+ asio_execution_schedule_fn::call_traits<S>::is_noexcept>
+{
+};
+
+#if defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
+
+template <typename S>
+constexpr bool is_nothrow_schedule_v
+ = is_nothrow_schedule<S>::value;
+
+#endif // defined(BOOST_ASIO_HAS_VARIABLE_TEMPLATES)
+
+} // namespace execution
+} // namespace asio
+} // namespace boost
+
+#endif // defined(GENERATING_DOCUMENTATION)
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_EXECUTION_SCHEDULE_HPP
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