288 lines
7.0 KiB
C++
288 lines
7.0 KiB
C++
//
|
|
// execution/schedule.hpp
|
|
// ~~~~~~~~~~~~~~~~~~~~~~
|
|
//
|
|
// Copyright (c) 2003-2021 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 ASIO_EXECUTION_SCHEDULE_HPP
|
|
#define ASIO_EXECUTION_SCHEDULE_HPP
|
|
|
|
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
# pragma once
|
|
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
|
|
#include "asio/detail/config.hpp"
|
|
#include "asio/detail/type_traits.hpp"
|
|
#include "asio/execution/executor.hpp"
|
|
#include "asio/traits/schedule_member.hpp"
|
|
#include "asio/traits/schedule_free.hpp"
|
|
|
|
#include "asio/detail/push_options.hpp"
|
|
|
|
#if defined(GENERATING_DOCUMENTATION)
|
|
|
|
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
|
|
|
|
#else // defined(GENERATING_DOCUMENTATION)
|
|
|
|
namespace asio_execution_schedule_fn {
|
|
|
|
using asio::decay;
|
|
using asio::declval;
|
|
using asio::enable_if;
|
|
using asio::execution::is_executor;
|
|
using asio::traits::schedule_free;
|
|
using asio::traits::schedule_member;
|
|
|
|
void schedule();
|
|
|
|
enum overload_type
|
|
{
|
|
identity,
|
|
call_member,
|
|
call_free,
|
|
ill_formed
|
|
};
|
|
|
|
template <typename S, typename = void, typename = void, typename = void>
|
|
struct call_traits
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed);
|
|
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>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
|
|
};
|
|
|
|
template <typename S>
|
|
struct call_traits<S,
|
|
typename enable_if<
|
|
!schedule_member<S>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
schedule_free<S>::is_valid
|
|
>::type> :
|
|
schedule_free<S>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
|
|
};
|
|
|
|
template <typename S>
|
|
struct call_traits<S,
|
|
typename enable_if<
|
|
!schedule_member<S>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
!schedule_free<S>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
is_executor<typename decay<S>::type>::value
|
|
>::type>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = identity);
|
|
ASIO_STATIC_CONSTEXPR(bool, is_noexcept = true);
|
|
|
|
#if defined(ASIO_HAS_MOVE)
|
|
typedef ASIO_MOVE_ARG(S) result_type;
|
|
#else // defined(ASIO_HAS_MOVE)
|
|
typedef ASIO_MOVE_ARG(typename decay<S>::type) result_type;
|
|
#endif // defined(ASIO_HAS_MOVE)
|
|
};
|
|
|
|
struct impl
|
|
{
|
|
template <typename S>
|
|
ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<S>::overload == identity,
|
|
typename call_traits<S>::result_type
|
|
>::type
|
|
operator()(ASIO_MOVE_ARG(S) s) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<S>::is_noexcept))
|
|
{
|
|
return ASIO_MOVE_CAST(S)(s);
|
|
}
|
|
|
|
#if defined(ASIO_HAS_MOVE)
|
|
template <typename S>
|
|
ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<S>::overload == call_member,
|
|
typename call_traits<S>::result_type
|
|
>::type
|
|
operator()(S&& s) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<S>::is_noexcept))
|
|
{
|
|
return ASIO_MOVE_CAST(S)(s).schedule();
|
|
}
|
|
|
|
template <typename S>
|
|
ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<S>::overload == call_free,
|
|
typename call_traits<S>::result_type
|
|
>::type
|
|
operator()(S&& s) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<S>::is_noexcept))
|
|
{
|
|
return schedule(ASIO_MOVE_CAST(S)(s));
|
|
}
|
|
#else // defined(ASIO_HAS_MOVE)
|
|
template <typename S>
|
|
ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<S&>::overload == call_member,
|
|
typename call_traits<S&>::result_type
|
|
>::type
|
|
operator()(S& s) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<S&>::is_noexcept))
|
|
{
|
|
return s.schedule();
|
|
}
|
|
|
|
template <typename S>
|
|
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
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<const S&>::is_noexcept))
|
|
{
|
|
return s.schedule();
|
|
}
|
|
|
|
template <typename S>
|
|
ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<S&>::overload == call_free,
|
|
typename call_traits<S&>::result_type
|
|
>::type
|
|
operator()(S& s) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<S&>::is_noexcept))
|
|
{
|
|
return schedule(s);
|
|
}
|
|
|
|
template <typename S>
|
|
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
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<const S&>::is_noexcept))
|
|
{
|
|
return schedule(s);
|
|
}
|
|
#endif // defined(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 asio {
|
|
namespace execution {
|
|
namespace {
|
|
|
|
static 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(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename S>
|
|
constexpr bool can_schedule_v = can_schedule<S>::value;
|
|
|
|
#endif // defined(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(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename S>
|
|
constexpr bool is_nothrow_schedule_v
|
|
= is_nothrow_schedule<S>::value;
|
|
|
|
#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
} // namespace execution
|
|
} // namespace asio
|
|
|
|
#endif // defined(GENERATING_DOCUMENTATION)
|
|
|
|
#include "asio/detail/pop_options.hpp"
|
|
|
|
#endif // ASIO_EXECUTION_SCHEDULE_HPP
|