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| 1 | +// |
| 2 | +// async_result.hpp |
| 3 | +// ~~~~~~~~~~~~~~~~ |
| 4 | +// |
| 5 | +// Copyright (c) 2003-2014 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
| 6 | +// |
| 7 | +// Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 8 | +// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| 9 | +// |
| 10 | + |
| 11 | +#ifndef BOOST_ASIO_ASYNC_RESULT_HPP |
| 12 | +#define BOOST_ASIO_ASYNC_RESULT_HPP |
| 13 | + |
| 14 | +#if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| 15 | +# pragma once |
| 16 | +#endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
| 17 | + |
| 18 | +#include <boost/asio/detail/config.hpp> |
| 19 | +#include <boost/asio/handler_type.hpp> |
| 20 | + |
| 21 | +#include <boost/asio/detail/push_options.hpp> |
| 22 | + |
| 23 | +namespace boost { |
| 24 | +namespace asio { |
| 25 | + |
| 26 | +/// An interface for customising the behaviour of an initiating function. |
| 27 | +/** |
| 28 | + * This template may be specialised for user-defined handler types. |
| 29 | + */ |
| 30 | +template <typename Handler> |
| 31 | +class async_result |
| 32 | +{ |
| 33 | +public: |
| 34 | + /// The return type of the initiating function. |
| 35 | + typedef void type; |
| 36 | + |
| 37 | + /// Construct an async result from a given handler. |
| 38 | + /** |
| 39 | + * When using a specalised async_result, the constructor has an opportunity |
| 40 | + * to initialise some state associated with the handler, which is then |
| 41 | + * returned from the initiating function. |
| 42 | + */ |
| 43 | + explicit async_result(Handler&) |
| 44 | + { |
| 45 | + } |
| 46 | + |
| 47 | + /// Obtain the value to be returned from the initiating function. |
| 48 | + type get() |
| 49 | + { |
| 50 | + } |
| 51 | +}; |
| 52 | + |
| 53 | +namespace detail { |
| 54 | + |
| 55 | +// Helper template to deduce the true type of a handler, capture a local copy |
| 56 | +// of the handler, and then create an async_result for the handler. |
| 57 | +template <typename Handler, typename Signature> |
| 58 | +struct async_result_init |
| 59 | +{ |
| 60 | + explicit async_result_init(BOOST_ASIO_MOVE_ARG(Handler) orig_handler) |
| 61 | + : handler(BOOST_ASIO_MOVE_CAST(Handler)(orig_handler)), |
| 62 | + result(handler) |
| 63 | + { |
| 64 | + } |
| 65 | + |
| 66 | + typename handler_type<Handler, Signature>::type handler; |
| 67 | + async_result<typename handler_type<Handler, Signature>::type> result; |
| 68 | +}; |
| 69 | + |
| 70 | +template <typename Handler, typename Signature> |
| 71 | +struct async_result_type_helper |
| 72 | +{ |
| 73 | + typedef typename async_result< |
| 74 | + typename handler_type<Handler, Signature>::type |
| 75 | + >::type type; |
| 76 | +}; |
| 77 | + |
| 78 | +} // namespace detail |
| 79 | +} // namespace asio |
| 80 | +} // namespace boost |
| 81 | + |
| 82 | +#include <boost/asio/detail/pop_options.hpp> |
| 83 | + |
| 84 | +#if defined(GENERATING_DOCUMENTATION) |
| 85 | +# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \ |
| 86 | + void_or_deduced |
| 87 | +#elif defined(_MSC_VER) && (_MSC_VER < 1500) |
| 88 | +# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \ |
| 89 | + typename ::boost::asio::detail::async_result_type_helper<h, sig>::type |
| 90 | +#else |
| 91 | +# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \ |
| 92 | + typename ::boost::asio::async_result< \ |
| 93 | + typename ::boost::asio::handler_type<h, sig>::type>::type |
| 94 | +#endif |
| 95 | + |
| 96 | +#endif // BOOST_ASIO_ASYNC_RESULT_HPP |
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