blah2/lib/asio-1.26.0/asio/experimental/use_promise.hpp
2023-05-04 20:55:37 +09:30

111 lines
3.1 KiB
C++

//
// experimental/use_promise.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2022 Klemens D. Morgenstern
// (klemens dot morgenstern at gmx dot net)
//
// 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_EXPERIMENTAL_USE_PROMISE_HPP
#define ASIO_EXPERIMENTAL_USE_PROMISE_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#include <memory>
#include "asio/detail/type_traits.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace experimental {
template <typename Allocator = std::allocator<void>>
struct use_promise_t
{
/// The allocator type. The allocator is used when constructing the
/// @c promise object for a given asynchronous operation.
typedef Allocator allocator_type;
/// Construct using default-constructed allocator.
ASIO_CONSTEXPR use_promise_t()
{
}
/// Construct using specified allocator.
explicit use_promise_t(const Allocator& allocator)
: allocator_(allocator)
{
}
/// Obtain allocator.
allocator_type get_allocator() const ASIO_NOEXCEPT
{
return allocator_;
}
/// Adapts an executor to add the @c use_promise_t completion token as the
/// default.
template <typename InnerExecutor>
struct executor_with_default : InnerExecutor
{
/// Specify @c use_promise_t as the default completion token type.
typedef use_promise_t<Allocator> default_completion_token_type;
/// Construct the adapted executor from the inner executor type.
executor_with_default(const InnerExecutor& ex) ASIO_NOEXCEPT
: InnerExecutor(ex)
{
}
/// Convert the specified executor to the inner executor type, then use
/// that to construct the adapted executor.
template <typename OtherExecutor>
executor_with_default(const OtherExecutor& ex,
typename constraint<
is_convertible<OtherExecutor, InnerExecutor>::value
>::type = 0) ASIO_NOEXCEPT
: InnerExecutor(ex)
{
}
};
/// Function helper to adapt an I/O object to use @c use_promise_t as its
/// default completion token type.
template <typename T>
static typename decay<T>::type::template rebind_executor<
executor_with_default<typename decay<T>::type::executor_type>
>::other
as_default_on(ASIO_MOVE_ARG(T) object)
{
return typename decay<T>::type::template rebind_executor<
executor_with_default<typename decay<T>::type::executor_type>
>::other(ASIO_MOVE_CAST(T)(object));
}
/// Specify an alternate allocator.
template <typename OtherAllocator>
use_promise_t<OtherAllocator> rebind(const OtherAllocator& allocator) const
{
return use_promise_t<OtherAllocator>(allocator);
}
private:
Allocator allocator_;
};
constexpr use_promise_t<> use_promise;
} // namespace experimental
} // namespace asio
#include "asio/detail/pop_options.hpp"
#include "asio/experimental/impl/use_promise.hpp"
#endif // ASIO_EXPERIMENTAL_USE_CORO_HPP