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- //
- // async_result.hpp
- // ~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2015 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_ASYNC_RESULT_HPP
- #define ASIO_ASYNC_RESULT_HPP
-
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
- #include "asio/detail/config.hpp"
- #include "asio/detail/type_traits.hpp"
- #include "asio/handler_type.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- /// An interface for customising the behaviour of an initiating function.
- /**
- * This template may be specialised for user-defined handler types.
- */
- template <typename Handler>
- class async_result
- {
- public:
- /// The return type of the initiating function.
- typedef void type;
-
- /// Construct an async result from a given handler.
- /**
- * When using a specalised async_result, the constructor has an opportunity
- * to initialise some state associated with the handler, which is then
- * returned from the initiating function.
- */
- explicit async_result(Handler&)
- {
- }
-
- /// Obtain the value to be returned from the initiating function.
- type get()
- {
- }
- };
-
- /// Helper template to deduce the real type of a handler, capture a local copy
- /// of the handler, and then create an async_result for the handler.
- template <typename Handler, typename Signature>
- struct async_completion
- {
- /// The real handler type to be used for the asynchronous operation.
- typedef typename asio::handler_type<
- Handler, Signature>::type handler_type;
-
- /// Constructor.
- /**
- * The constructor creates the concrete handler and makes the link between
- * the handler and the asynchronous result.
- */
- #if defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
- explicit async_completion(
- Handler& orig_handler)
- : handler(static_cast<typename conditional<
- is_same<Handler, handler_type>::value,
- handler_type&, Handler&&>::type>(orig_handler)),
- result(handler)
- {
- }
- #else // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
- explicit async_completion(const Handler& orig_handler)
- : handler(orig_handler),
- result(handler)
- {
- }
- #endif // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
-
- /// A copy of, or reference to, a real handler object.
- #if defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
- typename conditional<
- is_same<Handler, handler_type>::value,
- handler_type&, handler_type>::type handler;
- #else // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
- typename asio::handler_type<Handler, Signature>::type handler;
- #endif // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
-
- /// The result of the asynchronous operation's initiating function.
- async_result<typename asio::handler_type<
- Handler, Signature>::type> result;
- };
-
- namespace detail {
-
- template <typename Handler, typename Signature>
- struct async_result_type_helper
- {
- typedef typename async_result<
- typename handler_type<Handler, Signature>::type
- >::type type;
- };
-
- } // namespace detail
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #if defined(GENERATING_DOCUMENTATION)
- # define ASIO_INITFN_RESULT_TYPE(h, sig) \
- void_or_deduced
- #elif defined(_MSC_VER) && (_MSC_VER < 1500)
- # define ASIO_INITFN_RESULT_TYPE(h, sig) \
- typename ::asio::detail::async_result_type_helper<h, sig>::type
- #else
- # define ASIO_INITFN_RESULT_TYPE(h, sig) \
- typename ::asio::async_result< \
- typename ::asio::handler_type<h, sig>::type>::type
- #endif
-
- #endif // ASIO_ASYNC_RESULT_HPP
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