Initial Commit

include/asio/prepend.hpp

@@ -0,0 +1,66 @@
+//
+// prepend.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 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 ASIO_PREPEND_HPP
+#define ASIO_PREPEND_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <tuple>
+#include "asio/detail/type_traits.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+/// 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>
+  constexpr explicit prepend_t(T&& completion_token, V&&... values)
+    : token_(static_cast<T&&>(completion_token)),
+      values_(static_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>
+ASIO_NODISCARD inline constexpr
+prepend_t<decay_t<CompletionToken>, decay_t<Values>...>
+prepend(CompletionToken&& completion_token,
+    Values&&... values)
+{
+  return prepend_t<decay_t<CompletionToken>, decay_t<Values>...>(
+      static_cast<CompletionToken&&>(completion_token),
+      static_cast<Values&&>(values)...);
+}
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#include "asio/impl/prepend.hpp"
+
+#endif // ASIO_PREPEND_HPP