--- /dev/null
+//
+// experimental/prepend.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2022 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_EXPERIMENTAL_PREPEND_HPP
+#define BOOST_ASIO_EXPERIMENTAL_PREPEND_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <tuple>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace experimental {
+
+/// Completion token type used to specify that the completion handler
+/// arguments should be passed additional values before the results of the
+/// operation.
+template <typename CompletionToken, typename... Values>
+class prepend_t
+{
+public:
+ /// Constructor.
+ template <typename T, typename... V>
+ BOOST_ASIO_CONSTEXPR explicit prepend_t(
+ BOOST_ASIO_MOVE_ARG(T) completion_token,
+ BOOST_ASIO_MOVE_ARG(V)... values)
+ : token_(BOOST_ASIO_MOVE_CAST(T)(completion_token)),
+ values_(BOOST_ASIO_MOVE_CAST(V)(values)...)
+ {
+ }
+
+//private:
+ CompletionToken token_;
+ std::tuple<Values...> values_;
+};
+
+/// Completion token type used to specify that the completion handler
+/// arguments should be passed additional values before the results of the
+/// operation.
+template <typename CompletionToken, typename... Values>
+BOOST_ASIO_NODISCARD inline BOOST_ASIO_CONSTEXPR prepend_t<
+ typename decay<CompletionToken>::type, typename decay<Values>::type...>
+prepend(BOOST_ASIO_MOVE_ARG(CompletionToken) completion_token,
+ BOOST_ASIO_MOVE_ARG(Values)... values)
+{
+ return prepend_t<
+ typename decay<CompletionToken>::type, typename decay<Values>::type...>(
+ BOOST_ASIO_MOVE_CAST(CompletionToken)(completion_token),
+ BOOST_ASIO_MOVE_CAST(Values)(values)...);
+}
+
+} // namespace experimental
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/experimental/impl/prepend.hpp>
+
+#endif // BOOST_ASIO_EXPERIMENTAL_PREPEND_HPP