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+//
+// async_result.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2014 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_ASYNC_RESULT_HPP
+#define BOOST_ASIO_ASYNC_RESULT_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/handler_type.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// An interface for customising the behaviour of an initiating function.
+/**
+ * This template may be specialised for user-defined handler types.
+ */
+template <typename Handler>
+class async_result
+{
+public:
+ /// The return type of the initiating function.
+ typedef void type;
+
+ /// Construct an async result from a given handler.
+ /**
+ * When using a specalised async_result, the constructor has an opportunity
+ * to initialise some state associated with the handler, which is then
+ * returned from the initiating function.
+ */
+ explicit async_result(Handler&)
+ {
+ }
+
+ /// Obtain the value to be returned from the initiating function.
+ type get()
+ {
+ }
+};
+
+namespace detail {
+
+// Helper template to deduce the true type of a handler, capture a local copy
+// of the handler, and then create an async_result for the handler.
+template <typename Handler, typename Signature>
+struct async_result_init
+{
+ explicit async_result_init(BOOST_ASIO_MOVE_ARG(Handler) orig_handler)
+ : handler(BOOST_ASIO_MOVE_CAST(Handler)(orig_handler)),
+ result(handler)
+ {
+ }
+
+ typename handler_type<Handler, Signature>::type handler;
+ async_result<typename handler_type<Handler, Signature>::type> result;
+};
+
+template <typename Handler, typename Signature>
+struct async_result_type_helper
+{
+ typedef typename async_result<
+ typename handler_type<Handler, Signature>::type
+ >::type type;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#if defined(GENERATING_DOCUMENTATION)
+# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
+ void_or_deduced
+#elif defined(_MSC_VER) && (_MSC_VER < 1500)
+# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
+ typename ::boost::asio::detail::async_result_type_helper<h, sig>::type
+#else
+# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
+ typename ::boost::asio::async_result< \
+ typename ::boost::asio::handler_type<h, sig>::type>::type
+#endif
+
+#endif // BOOST_ASIO_ASYNC_RESULT_HPP