1 //  (C) Copyright Jeremy Siek 1999.

     2 // Distributed under the Boost Software License, Version 1.0. (See

     3 // accompanying file LICENSE_1_0.txt or copy at

     4 // http://www.boost.org/LICENSE_1_0.txt)

     5 

     6 #ifndef BOOST_TREE_STRUCTURE_HPP

     7 #define BOOST_TREE_STRUCTURE_HPP

     8 

     9 namespace boost {

    10 

    11   template <class T>

    12   struct tree_traits {

    13     typedef typename T::node_descriptor node_descriptor;    

    14     typedef typename T::children_iterator children_iterator;    

    15   };

    16 

    17 

    18   template <class Tree, class TreeVisitor>

    19   void traverse_tree(typename tree_traits<Tree>::node_descriptor v,

    20                      Tree& t, TreeVisitor visitor)

    21   {

    22     visitor.preorder(v, t);

    23     typename tree_traits<Tree>::children_iterator i, end;

    24     tie(i, end) = children(v, t);

    25     if (i != end) {

    26       traverse_tree(*i++, t, visitor);

    27       visitor.inorder(v, t);

    28       while (i != end)

    29         traverse_tree(*i++, t, visitor);

    30     } else

    31       visitor.inorder(v, t);

    32     visitor.postorder(v, t);

    33   }

    34 

    35   struct null_tree_visitor {

    36     template <typename Node, typename Tree> void preorder(Node, Tree&) { }

    37     template <typename Node, typename Tree> void inorder(Node, Tree&) { }

    38     template <typename Node, typename Tree> void postorder(Node, Tree&) { }

    39   };

    40 

    41 } /* namespace boost */

    42 

    43 #endif /* BOOST_TREE_STRUCTURE_HPP */