williamr@2: //  (C) Copyright Jeremy Siek 1999.
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: #ifndef BOOST_TREE_STRUCTURE_HPP
williamr@2: #define BOOST_TREE_STRUCTURE_HPP
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2:   template <class T>
williamr@2:   struct tree_traits {
williamr@2:     typedef typename T::node_descriptor node_descriptor;    
williamr@2:     typedef typename T::children_iterator children_iterator;    
williamr@2:   };
williamr@2: 
williamr@2: 
williamr@2:   template <class Tree, class TreeVisitor>
williamr@2:   void traverse_tree(typename tree_traits<Tree>::node_descriptor v,
williamr@2:                      Tree& t, TreeVisitor visitor)
williamr@2:   {
williamr@2:     visitor.preorder(v, t);
williamr@2:     typename tree_traits<Tree>::children_iterator i, end;
williamr@2:     tie(i, end) = children(v, t);
williamr@2:     if (i != end) {
williamr@2:       traverse_tree(*i++, t, visitor);
williamr@2:       visitor.inorder(v, t);
williamr@2:       while (i != end)
williamr@2:         traverse_tree(*i++, t, visitor);
williamr@2:     } else
williamr@2:       visitor.inorder(v, t);
williamr@2:     visitor.postorder(v, t);
williamr@2:   }
williamr@2: 
williamr@2:   struct null_tree_visitor {
williamr@2:     template <typename Node, typename Tree> void preorder(Node, Tree&) { }
williamr@2:     template <typename Node, typename Tree> void inorder(Node, Tree&) { }
williamr@2:     template <typename Node, typename Tree> void postorder(Node, Tree&) { }
williamr@2:   };
williamr@2: 
williamr@2: } /* namespace boost */
williamr@2: 
williamr@2: #endif /* BOOST_TREE_STRUCTURE_HPP */