112 lines
3.1 KiB
C++
112 lines
3.1 KiB
C++
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//
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// experimental/use_promise.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2021-2023 Klemens D. Morgenstern
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// (klemens dot morgenstern at gmx dot net)
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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_EXPERIMENTAL_USE_PROMISE_HPP
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#define ASIO_EXPERIMENTAL_USE_PROMISE_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 <memory>
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#include "asio/detail/type_traits.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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namespace experimental {
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template <typename Allocator = std::allocator<void>>
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struct use_promise_t
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{
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/// The allocator type. The allocator is used when constructing the
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/// @c promise object for a given asynchronous operation.
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typedef Allocator allocator_type;
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/// Construct using default-constructed allocator.
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ASIO_CONSTEXPR use_promise_t()
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{
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}
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/// Construct using specified allocator.
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explicit use_promise_t(const Allocator& allocator)
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: allocator_(allocator)
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{
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}
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/// Obtain allocator.
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allocator_type get_allocator() const ASIO_NOEXCEPT
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{
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return allocator_;
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}
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/// Adapts an executor to add the @c use_promise_t completion token as the
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/// default.
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template <typename InnerExecutor>
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struct executor_with_default : InnerExecutor
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{
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/// Specify @c use_promise_t as the default completion token type.
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typedef use_promise_t<Allocator> default_completion_token_type;
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/// Construct the adapted executor from the inner executor type.
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executor_with_default(const InnerExecutor& ex) ASIO_NOEXCEPT
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: InnerExecutor(ex)
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{
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}
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/// Convert the specified executor to the inner executor type, then use
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/// that to construct the adapted executor.
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template <typename OtherExecutor>
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executor_with_default(const OtherExecutor& ex,
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typename constraint<
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is_convertible<OtherExecutor, InnerExecutor>::value
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>::type = 0) ASIO_NOEXCEPT
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: InnerExecutor(ex)
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{
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}
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};
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/// Function helper to adapt an I/O object to use @c use_promise_t as its
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/// default completion token type.
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template <typename T>
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static typename decay<T>::type::template rebind_executor<
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executor_with_default<typename decay<T>::type::executor_type>
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>::other
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as_default_on(ASIO_MOVE_ARG(T) object)
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{
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return typename decay<T>::type::template rebind_executor<
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executor_with_default<typename decay<T>::type::executor_type>
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>::other(ASIO_MOVE_CAST(T)(object));
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}
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/// Specify an alternate allocator.
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template <typename OtherAllocator>
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use_promise_t<OtherAllocator> rebind(const OtherAllocator& allocator) const
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{
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return use_promise_t<OtherAllocator>(allocator);
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}
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private:
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Allocator allocator_;
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};
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constexpr use_promise_t<> use_promise;
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} // namespace experimental
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#include "asio/experimental/impl/use_promise.hpp"
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#endif // ASIO_EXPERIMENTAL_USE_CORO_HPP
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