experimental/impl/as_single.hpp

0001 //
0002 // experimental/impl/as_single.hpp
0003 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010
0011 #ifndef BOOST_ASIO_IMPL_EXPERIMENTAL_AS_SINGLE_HPP
0012 #define BOOST_ASIO_IMPL_EXPERIMENTAL_AS_SINGLE_HPP
0013
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017
0018 #include <boost/asio/detail/config.hpp>
0019 #include <tuple>
0020 #include <boost/asio/associator.hpp>
0021 #include <boost/asio/async_result.hpp>
0022 #include <boost/asio/detail/handler_cont_helpers.hpp>
0023 #include <boost/asio/detail/type_traits.hpp>
0024
0025 #include <boost/asio/detail/push_options.hpp>
0026
0027 namespace boost {
0028 namespace asio {
0029 namespace experimental {
0030 namespace detail {
0031
0032 // Class to adapt a as_single_t as a completion handler.
0033 template <typename Handler>
0034 class as_single_handler
0035 {
0036 public:
0037   typedef void result_type;
0038
0039   template <typename CompletionToken>
0040   as_single_handler(as_single_t<CompletionToken> e)
0041     : handler_(static_cast<CompletionToken&&>(e.token_))
0042   {
0043   }
0044
0045   template <typename RedirectedHandler>
0046   as_single_handler(RedirectedHandler&& h)
0047     : handler_(static_cast<RedirectedHandler&&>(h))
0048   {
0049   }
0050
0051   void operator()()
0052   {
0053     static_cast<Handler&&>(handler_)();
0054   }
0055
0056   template <typename Arg>
0057   void operator()(Arg&& arg)
0058   {
0059     static_cast<Handler&&>(handler_)(static_cast<Arg&&>(arg));
0060   }
0061
0062   template <typename... Args>
0063   void operator()(Args&&... args)
0064   {
0065     static_cast<Handler&&>(handler_)(
0066         std::make_tuple(static_cast<Args&&>(args)...));
0067   }
0068
0069 //private:
0070   Handler handler_;
0071 };
0072
0073 template <typename Handler>
0074 inline bool asio_handler_is_continuation(
0075     as_single_handler<Handler>* this_handler)
0076 {
0077   return boost_asio_handler_cont_helpers::is_continuation(
0078         this_handler->handler_);
0079 }
0080
0081 template <typename Signature>
0082 struct as_single_signature
0083 {
0084   typedef Signature type;
0085 };
0086
0087 template <typename R>
0088 struct as_single_signature<R()>
0089 {
0090   typedef R type();
0091 };
0092
0093 template <typename R, typename Arg>
0094 struct as_single_signature<R(Arg)>
0095 {
0096   typedef R type(Arg);
0097 };
0098
0099 template <typename R, typename... Args>
0100 struct as_single_signature<R(Args...)>
0101 {
0102   typedef R type(std::tuple<decay_t<Args>...>);
0103 };
0104
0105 } // namespace detail
0106 } // namespace experimental
0107
0108 #if !defined(GENERATING_DOCUMENTATION)
0109
0110 template <typename CompletionToken, typename Signature>
0111 struct async_result<experimental::as_single_t<CompletionToken>, Signature>
0112 {
0113   template <typename Initiation>
0114   struct init_wrapper
0115   {
0116     init_wrapper(Initiation init)
0117       : initiation_(static_cast<Initiation&&>(init))
0118     {
0119     }
0120
0121     template <typename Handler, typename... Args>
0122     void operator()(Handler&& handler, Args&&... args)
0123     {
0124       static_cast<Initiation&&>(initiation_)(
0125           experimental::detail::as_single_handler<decay_t<Handler>>(
0126             static_cast<Handler&&>(handler)),
0127           static_cast<Args&&>(args)...);
0128     }
0129
0130     Initiation initiation_;
0131   };
0132
0133   template <typename Initiation, typename RawCompletionToken, typename... Args>
0134   static auto initiate(Initiation&& initiation,
0135       RawCompletionToken&& token, Args&&... args)
0136     -> decltype(
0137       async_initiate<CompletionToken,
0138         typename experimental::detail::as_single_signature<Signature>::type>(
0139           init_wrapper<decay_t<Initiation>>(
0140             static_cast<Initiation&&>(initiation)),
0141           token.token_, static_cast<Args&&>(args)...))
0142   {
0143     return async_initiate<CompletionToken,
0144       typename experimental::detail::as_single_signature<Signature>::type>(
0145         init_wrapper<decay_t<Initiation>>(
0146           static_cast<Initiation&&>(initiation)),
0147         token.token_, static_cast<Args&&>(args)...);
0148   }
0149 };
0150
0151 template <template <typename, typename> class Associator,
0152     typename Handler, typename DefaultCandidate>
0153 struct associator<Associator,
0154     experimental::detail::as_single_handler<Handler>, DefaultCandidate>
0155   : Associator<Handler, DefaultCandidate>
0156 {
0157   static typename Associator<Handler, DefaultCandidate>::type get(
0158       const experimental::detail::as_single_handler<Handler>& h) noexcept
0159   {
0160     return Associator<Handler, DefaultCandidate>::get(h.handler_);
0161   }
0162
0163   static auto get(const experimental::detail::as_single_handler<Handler>& h,
0164       const DefaultCandidate& c) noexcept
0165     -> decltype(Associator<Handler, DefaultCandidate>::get(h.handler_, c))
0166   {
0167     return Associator<Handler, DefaultCandidate>::get(h.handler_, c);
0168   }
0169 };
0170
0171 #endif // !defined(GENERATING_DOCUMENTATION)
0172
0173 } // namespace asio
0174 } // namespace boost
0175
0176 #include <boost/asio/detail/pop_options.hpp>
0177
0178 #endif // BOOST_ASIO_IMPL_EXPERIMENTAL_AS_SINGLE_HPP