added asio

include/asio/detail/null_fenced_block.hpp

@@ -0,0 +1,47 @@
+//
+// detail/null_fenced_block.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_DETAIL_NULL_FENCED_BLOCK_HPP
+#define ASIO_DETAIL_NULL_FENCED_BLOCK_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/noncopyable.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+class null_fenced_block
+  : private noncopyable
+{
+public:
+  enum half_or_full_t { half, full };
+
+  // Constructor.
+  explicit null_fenced_block(half_or_full_t)
+  {
+  }
+
+  // Destructor.
+  ~null_fenced_block()
+  {
+  }
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_NULL_FENCED_BLOCK_HPP