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- //
- // handler_type.hpp
- // ~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2018 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 BOOST_ASIO_HANDLER_TYPE_HPP
- #define BOOST_ASIO_HANDLER_TYPE_HPP
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
- #include <boost/asio/detail/config.hpp>
- #include <boost/asio/detail/type_traits.hpp>
- #include <boost/asio/detail/push_options.hpp>
- namespace boost {
- namespace asio {
- /// (Deprecated: Use two-parameter version of async_result.) Default handler
- /// type traits provided for all completion token types.
- /**
- * The handler_type traits class is used for determining the concrete handler
- * type to be used for an asynchronous operation. It allows the handler type to
- * be determined at the point where the specific completion handler signature
- * is known.
- *
- * This template may be specialised for user-defined completion token types.
- */
- template <typename CompletionToken, typename Signature, typename = void>
- struct handler_type
- {
- /// The handler type for the specific signature.
- typedef typename conditional<
- is_same<CompletionToken, typename decay<CompletionToken>::type>::value,
- decay<CompletionToken>,
- handler_type<typename decay<CompletionToken>::type, Signature>
- >::type::type type;
- };
- } // namespace asio
- } // namespace boost
- #include <boost/asio/detail/pop_options.hpp>
- #endif // BOOST_ASIO_HANDLER_TYPE_HPP
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