Added thirdparty: boost library

thirdparty/include/boost/mysql/detail/access.hpp

@@ -0,0 +1,44 @@
+//
+// Copyright (c) 2019-2023 Ruben Perez Hidalgo (rubenperez038 at gmail 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_MYSQL_DETAIL_ACCESS_HPP
+#define BOOST_MYSQL_DETAIL_ACCESS_HPP
+
+#include <utility>
+
+namespace boost {
+namespace mysql {
+namespace detail {
+
+// Exposes access to the implementation of public access, which is sometimes
+// required by library internals.
+struct access
+{
+    template <class T>
+    static decltype(std::declval<T>().impl_)& get_impl(T& obj) noexcept
+    {
+        return obj.impl_;
+    }
+
+    template <class T>
+    static const decltype(std::declval<T>().impl_)& get_impl(const T& obj) noexcept
+    {
+        return obj.impl_;
+    }
+
+    template <class T, class... Args>
+    static T construct(Args&&... args)
+    {
+        return T(std::forward<Args>(args)...);
+    }
+};
+
+}  // namespace detail
+}  // namespace mysql
+}  // namespace boost
+
+#endif