145 lines
3.4 KiB
C++
Executable File
145 lines
3.4 KiB
C++
Executable File
//
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// awaitable.hpp
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// ~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2022 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 BOOST_ASIO_AWAITABLE_HPP
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#define BOOST_ASIO_AWAITABLE_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 <boost/asio/detail/config.hpp>
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#if defined(BOOST_ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)
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#if defined(BOOST_ASIO_HAS_STD_COROUTINE)
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# include <coroutine>
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#else // defined(BOOST_ASIO_HAS_STD_COROUTINE)
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# include <experimental/coroutine>
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#endif // defined(BOOST_ASIO_HAS_STD_COROUTINE)
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#include <utility>
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#include <boost/asio/any_io_executor.hpp>
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#include <boost/asio/detail/push_options.hpp>
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namespace boost {
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namespace asio {
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namespace detail {
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#if defined(BOOST_ASIO_HAS_STD_COROUTINE)
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using std::coroutine_handle;
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using std::suspend_always;
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#else // defined(BOOST_ASIO_HAS_STD_COROUTINE)
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using std::experimental::coroutine_handle;
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using std::experimental::suspend_always;
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#endif // defined(BOOST_ASIO_HAS_STD_COROUTINE)
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template <typename> class awaitable_thread;
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template <typename, typename> class awaitable_frame;
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} // namespace detail
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/// The return type of a coroutine or asynchronous operation.
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template <typename T, typename Executor = any_io_executor>
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class BOOST_ASIO_NODISCARD awaitable
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{
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public:
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/// The type of the awaited value.
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typedef T value_type;
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/// The executor type that will be used for the coroutine.
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typedef Executor executor_type;
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/// Default constructor.
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constexpr awaitable() noexcept
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: frame_(nullptr)
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{
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}
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/// Move constructor.
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awaitable(awaitable&& other) noexcept
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: frame_(std::exchange(other.frame_, nullptr))
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{
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}
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/// Destructor
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~awaitable()
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{
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if (frame_)
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frame_->destroy();
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}
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/// Move assignment.
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awaitable& operator=(awaitable&& other) noexcept
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{
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if (this != &other)
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frame_ = std::exchange(other.frame_, nullptr);
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return *this;
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}
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/// Checks if the awaitable refers to a future result.
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bool valid() const noexcept
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{
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return !!frame_;
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}
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#if !defined(GENERATING_DOCUMENTATION)
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// Support for co_await keyword.
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bool await_ready() const noexcept
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{
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return false;
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}
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// Support for co_await keyword.
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template <class U>
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void await_suspend(
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detail::coroutine_handle<detail::awaitable_frame<U, Executor>> h)
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{
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frame_->push_frame(&h.promise());
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}
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// Support for co_await keyword.
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T await_resume()
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{
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return awaitable(static_cast<awaitable&&>(*this)).frame_->get();
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}
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#endif // !defined(GENERATING_DOCUMENTATION)
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private:
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template <typename> friend class detail::awaitable_thread;
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template <typename, typename> friend class detail::awaitable_frame;
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// Not copy constructible or copy assignable.
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awaitable(const awaitable&) = delete;
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awaitable& operator=(const awaitable&) = delete;
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// Construct the awaitable from a coroutine's frame object.
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explicit awaitable(detail::awaitable_frame<T, Executor>* a)
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: frame_(a)
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{
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}
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detail::awaitable_frame<T, Executor>* frame_;
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};
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} // namespace asio
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} // namespace boost
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#include <boost/asio/detail/pop_options.hpp>
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#include <boost/asio/impl/awaitable.hpp>
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#endif // defined(BOOST_ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)
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#endif // BOOST_ASIO_AWAITABLE_HPP
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