ceph/src/boost/boost/asio/handler_type.hpp

   1 //
   2 // handler_type.hpp
   3 // ~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 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_HANDLER_TYPE_HPP
  12 #define BOOST_ASIO_HANDLER_TYPE_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/detail/type_traits.hpp>
  20
  21 #include <boost/asio/detail/push_options.hpp>
  22
  23 namespace boost {
  24 namespace asio {
  25
  26 /// (Deprecated: Use two-parameter version of async_result.) Default handler
  27 /// type traits provided for all completion token types.
  28 /**
  29  * The handler_type traits class is used for determining the concrete handler
  30  * type to be used for an asynchronous operation. It allows the handler type to
  31  * be determined at the point where the specific completion handler signature
  32  * is known.
  33  *
  34  * This template may be specialised for user-defined completion token types.
  35  */
  36 template <typename CompletionToken, typename Signature, typename = void>
  37 struct handler_type
  38 {
  39   /// The handler type for the specific signature.
  40   typedef typename conditional<
  41     is_same<CompletionToken, typename decay<CompletionToken>::type>::value,
  42     decay<CompletionToken>,
  43     handler_type<typename decay<CompletionToken>::type, Signature>
  44   >::type::type type;
  45 };
  46
  47 } // namespace asio
  48 } // namespace boost
  49
  50 #include <boost/asio/detail/pop_options.hpp>
  51
  52 #endif // BOOST_ASIO_HANDLER_TYPE_HPP