Imported existing code

libraries/include/boost/intrusive/derivation_value_traits.hpp

@@ -0,0 +1,56 @@
+/////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga  2006-2008
+//
+// 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)
+//
+// See http://www.boost.org/libs/intrusive for documentation.
+//
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef BOOST_INTRUSIVE_DERIVATION_VALUE_TRAITS_HPP
+#define BOOST_INTRUSIVE_DERIVATION_VALUE_TRAITS_HPP
+
+#include <boost/intrusive/link_mode.hpp>
+#include <iterator>
+
+namespace boost {
+namespace intrusive {
+
+//!This value traits template is used to create value traits
+//!from user defined node traits where value_traits::value_type will
+//!derive from node_traits::node
+template<class T, class NodeTraits, link_mode_type LinkMode = safe_link>
+struct derivation_value_traits
+{
+   public:
+   typedef NodeTraits                                                node_traits;
+   typedef T                                                         value_type;
+   typedef typename node_traits::node                                node;
+   typedef typename node_traits::node_ptr                            node_ptr;
+   typedef typename node_traits::const_node_ptr                      const_node_ptr;
+   typedef typename boost::pointer_to_other<node_ptr, T>::type       pointer;
+   typedef typename boost::pointer_to_other<node_ptr, const T>::type const_pointer;
+   typedef typename std::iterator_traits<pointer>::reference         reference;
+   typedef typename std::iterator_traits<const_pointer>::reference   const_reference;
+   static const link_mode_type link_mode = LinkMode;
+
+   static node_ptr to_node_ptr(reference value)
+   { return node_ptr(&value); }
+
+   static const_node_ptr to_node_ptr(const_reference value)
+   { return node_ptr(&value); }
+
+   static pointer to_value_ptr(node_ptr n) 
+   {  return pointer(static_cast<T*>(detail::get_pointer(n))); }
+
+   static const_pointer to_value_ptr(const_node_ptr n)
+   {  return const_pointer(static_cast<T*>(detail::get_pointer(n))); }
+};
+
+} //namespace intrusive 
+} //namespace boost 
+
+#endif //BOOST_INTRUSIVE_DERIVATION_VALUE_TRAITS_HPP