ceph/src/boost/boost/asio/compose.hpp

   1 //
   2 // compose.hpp
   3 // ~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2019 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_COMPOSE_HPP
  12 #define BOOST_ASIO_COMPOSE_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/async_result.hpp>
  20
  21 #include <boost/asio/detail/push_options.hpp>
  22
  23 namespace boost {
  24 namespace asio {
  25
  26 #if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES) \
  27   || defined(GENERATING_DOCUMENTATION)
  28
  29 /// Launch an asynchronous operation with a stateful implementation.
  30 /**
  31  * The async_compose function simplifies the implementation of composed
  32  * asynchronous operations automatically wrapping a stateful function object
  33  * with a conforming intermediate completion handler.
  34  *
  35  * @param implementation A function object that contains the implementation of
  36  * the composed asynchronous operation. The first argument to the function
  37  * object is a non-const reference to the enclosing intermediate completion
  38  * handler. The remaining arguments are any arguments that originate from the
  39  * completion handlers of any asynchronous operations performed by the
  40  * implementation.
  41
  42  * @param token The completion token.
  43  *
  44  * @param io_objects_or_executors Zero or more I/O objects or I/O executors for
  45  * which outstanding work must be maintained.
  46  *
  47  * @par Example:
  48  *
  49  * @code struct async_echo_implementation
  50  * {
  51  *   tcp::socket& socket_;
  52  *   boost::asio::mutable_buffer buffer_;
  53  *   enum { starting, reading, writing } state_;
  54  *
  55  *   template <typename Self>
  56  *   void operator()(Self& self,
  57  *       boost::system::error_code error = {},
  58  *       std::size_t n = 0)
  59  *   {
  60  *     switch (state_)
  61  *     {
  62  *     case starting:
  63  *       state_ = reading;
  64  *       socket_.async_read_some(
  65  *           buffer_, std::move(self));
  66  *       break;
  67  *     case reading:
  68  *       if (error)
  69  *       {
  70  *         self.complete(error, 0);
  71  *       }
  72  *       else
  73  *       {
  74  *         state_ = writing;
  75  *         boost::asio::async_write(socket_, buffer_,
  76  *             boost::asio::transfer_exactly(n),
  77  *             std::move(self));
  78  *       }
  79  *       break;
  80  *     case writing:
  81  *       self.complete(error, n);
  82  *       break;
  83  *     }
  84  *   }
  85  * };
  86  *
  87  * template <typename CompletionToken>
  88  * auto async_echo(tcp::socket& socket,
  89  *     boost::asio::mutable_buffer buffer,
  90  *     CompletionToken&& token) ->
  91  *   typename boost::asio::async_result<
  92  *     typename std::decay<CompletionToken>::type,
  93  *       void(boost::system::error_code, std::size_t)>::return_type
  94  * {
  95  *   return boost::asio::async_compose<CompletionToken,
  96  *     void(boost::system::error_code, std::size_t)>(
  97  *       async_echo_implementation{socket, buffer,
  98  *         async_echo_implementation::starting},
  99  *       token, socket);
 100  * } @endcode
 101  */
 102 template <typename CompletionToken, typename Signature,
 103     typename Implementation, typename... IoObjectsOrExecutors>
 104 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature)
 105 async_compose(BOOST_ASIO_MOVE_ARG(Implementation) implementation,
 106     BOOST_ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token,
 107     BOOST_ASIO_MOVE_ARG(IoObjectsOrExecutors)... io_objects_or_executors);
 108
 109 #else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 110       //   || defined(GENERATING_DOCUMENTATION)
 111
 112 template <typename CompletionToken, typename Signature, typename Implementation>
 113 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature)
 114 async_compose(BOOST_ASIO_MOVE_ARG(Implementation) implementation,
 115     BOOST_ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token);
 116
 117 #define BOOST_ASIO_PRIVATE_ASYNC_COMPOSE_DEF(n) \
 118   template <typename CompletionToken, typename Signature, \
 119       typename Implementation, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
 120   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature) \
 121   async_compose(BOOST_ASIO_MOVE_ARG(Implementation) implementation, \
 122       BOOST_ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token, \
 123       BOOST_ASIO_VARIADIC_MOVE_PARAMS(n));
 124   /**/
 125   BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_ASYNC_COMPOSE_DEF)
 126 #undef BOOST_ASIO_PRIVATE_ASYNC_COMPOSE_DEF
 127
 128 #endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 129        //   || defined(GENERATING_DOCUMENTATION)
 130
 131 } // namespace asio
 132 } // namespace boost
 133
 134 #include <boost/asio/detail/pop_options.hpp>
 135
 136 #include <boost/asio/impl/compose.hpp>
 137
 138 #endif // BOOST_ASIO_COMPOSE_HPP