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- //
- // compose.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_COMPOSE_HPP
- #define ASIO_COMPOSE_HPP
-
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
- #include "asio/detail/config.hpp"
- #include "asio/async_result.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- #if defined(ASIO_HAS_VARIADIC_TEMPLATES) \
- || defined(GENERATING_DOCUMENTATION)
-
- /// Launch an asynchronous operation with a stateful implementation.
- /**
- * The async_compose function simplifies the implementation of composed
- * asynchronous operations automatically wrapping a stateful function object
- * with a conforming intermediate completion handler.
- *
- * @param implementation A function object that contains the implementation of
- * the composed asynchronous operation. The first argument to the function
- * object is a non-const reference to the enclosing intermediate completion
- * handler. The remaining arguments are any arguments that originate from the
- * completion handlers of any asynchronous operations performed by the
- * implementation.
-
- * @param token The completion token.
- *
- * @param io_objects_or_executors Zero or more I/O objects or I/O executors for
- * which outstanding work must be maintained.
- *
- * @par Example:
- *
- * @code struct async_echo_implementation
- * {
- * tcp::socket& socket_;
- * asio::mutable_buffer buffer_;
- * enum { starting, reading, writing } state_;
- *
- * template <typename Self>
- * void operator()(Self& self,
- * asio::error_code error = {},
- * std::size_t n = 0)
- * {
- * switch (state_)
- * {
- * case starting:
- * state_ = reading;
- * socket_.async_read_some(
- * buffer_, std::move(self));
- * break;
- * case reading:
- * if (error)
- * {
- * self.complete(error, 0);
- * }
- * else
- * {
- * state_ = writing;
- * asio::async_write(socket_, buffer_,
- * asio::transfer_exactly(n),
- * std::move(self));
- * }
- * break;
- * case writing:
- * self.complete(error, n);
- * break;
- * }
- * }
- * };
- *
- * template <typename CompletionToken>
- * auto async_echo(tcp::socket& socket,
- * asio::mutable_buffer buffer,
- * CompletionToken&& token) ->
- * typename asio::async_result<
- * typename std::decay<CompletionToken>::type,
- * void(asio::error_code, std::size_t)>::return_type
- * {
- * return asio::async_compose<CompletionToken,
- * void(asio::error_code, std::size_t)>(
- * async_echo_implementation{socket, buffer,
- * async_echo_implementation::starting},
- * token, socket);
- * } @endcode
- */
- template <typename CompletionToken, typename Signature,
- typename Implementation, typename... IoObjectsOrExecutors>
- ASIO_INITFN_RESULT_TYPE(CompletionToken, Signature)
- async_compose(ASIO_MOVE_ARG(Implementation) implementation,
- ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token,
- ASIO_MOVE_ARG(IoObjectsOrExecutors)... io_objects_or_executors);
-
- #else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
- // || defined(GENERATING_DOCUMENTATION)
-
- template <typename CompletionToken, typename Signature, typename Implementation>
- ASIO_INITFN_RESULT_TYPE(CompletionToken, Signature)
- async_compose(ASIO_MOVE_ARG(Implementation) implementation,
- ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token);
-
- #define ASIO_PRIVATE_ASYNC_COMPOSE_DEF(n) \
- template <typename CompletionToken, typename Signature, \
- typename Implementation, ASIO_VARIADIC_TPARAMS(n)> \
- ASIO_INITFN_RESULT_TYPE(CompletionToken, Signature) \
- async_compose(ASIO_MOVE_ARG(Implementation) implementation, \
- ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token, \
- ASIO_VARIADIC_MOVE_PARAMS(n));
- /**/
- ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_ASYNC_COMPOSE_DEF)
- #undef ASIO_PRIVATE_ASYNC_COMPOSE_DEF
-
- #endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
- // || defined(GENERATING_DOCUMENTATION)
-
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #include "asio/impl/compose.hpp"
-
- #endif // ASIO_COMPOSE_HPP
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