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- //
- // use_awaitable.hpp
- // ~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 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_USE_AWAITABLE_HPP
- #define ASIO_USE_AWAITABLE_HPP
-
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
- #include "asio/detail/config.hpp"
-
- #if defined(ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)
-
- #include "asio/awaitable.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- /// A completion token that represents the currently executing coroutine.
- /**
- * The @c use_awaitable_t class, with its value @c use_awaitable, is used to
- * represent the currently executing coroutine. This completion token may be
- * passed as a handler to an asynchronous operation. For example:
- *
- * @code awaitable<void> my_coroutine()
- * {
- * std::size_t n = co_await my_socket.async_read_some(buffer, use_awaitable);
- * ...
- * } @endcode
- *
- * When used with co_await, the initiating function (@c async_read_some in the
- * above example) suspends the current coroutine. The coroutine is resumed when
- * the asynchronous operation completes, and the result of the operation is
- * returned.
- */
- template <typename Executor = executor>
- struct use_awaitable_t
- {
- ASIO_CONSTEXPR use_awaitable_t()
- {
- }
- };
-
- /// A completion token object that represents the currently executing coroutine.
- /**
- * See the documentation for asio::use_awaitable_t for a usage example.
- */
- #if defined(ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION)
- constexpr use_awaitable_t<> use_awaitable;
- #elif defined(ASIO_MSVC)
- __declspec(selectany) use_awaitable_t<> use_awaitable;
- #endif
-
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #include "asio/impl/use_awaitable.hpp"
-
- #endif // defined(ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)
-
- #endif // ASIO_USE_AWAITABLE_HPP
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