sl@0: //  (C) Copyright Jeremy Siek 1999.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: 
sl@0: #ifndef BOOST_TREE_STRUCTURE_HPP
sl@0: #define BOOST_TREE_STRUCTURE_HPP
sl@0: 
sl@0: namespace boost {
sl@0: 
sl@0:   template <class T>
sl@0:   struct tree_traits {
sl@0:     typedef typename T::node_descriptor node_descriptor;    
sl@0:     typedef typename T::children_iterator children_iterator;    
sl@0:   };
sl@0: 
sl@0: 
sl@0:   template <class Tree, class TreeVisitor>
sl@0:   void traverse_tree(typename tree_traits<Tree>::node_descriptor v,
sl@0:                      Tree& t, TreeVisitor visitor)
sl@0:   {
sl@0:     visitor.preorder(v, t);
sl@0:     typename tree_traits<Tree>::children_iterator i, end;
sl@0:     tie(i, end) = children(v, t);
sl@0:     if (i != end) {
sl@0:       traverse_tree(*i++, t, visitor);
sl@0:       visitor.inorder(v, t);
sl@0:       while (i != end)
sl@0:         traverse_tree(*i++, t, visitor);
sl@0:     } else
sl@0:       visitor.inorder(v, t);
sl@0:     visitor.postorder(v, t);
sl@0:   }
sl@0: 
sl@0:   struct null_tree_visitor {
sl@0:     template <typename Node, typename Tree> void preorder(Node, Tree&) { }
sl@0:     template <typename Node, typename Tree> void inorder(Node, Tree&) { }
sl@0:     template <typename Node, typename Tree> void postorder(Node, Tree&) { }
sl@0:   };
sl@0: 
sl@0: } /* namespace boost */
sl@0: 
sl@0: #endif /* BOOST_TREE_STRUCTURE_HPP */