namespace boost {
  namespace text {
    template<typename Key> struct const_trie_set_iterator;
    template<typename Key, typename Compare> struct trie_set;
    template<typename Key> struct trie_set_iterator;

    typedef stl_interfaces::reverse_iterator< trie_set_iterator< Key > > reverse_trie_set_iterator;
    typedef stl_interfaces::reverse_iterator< const_trie_set_iterator< Key > > const_reverse_trie_set_iterator;
  }
}