// the name of the operation should really be collect_subclasses

*operation* void collect_alternatives(Path_constraint_exp* c,
				      Vertex *             svertex,
				      Vertex_List*         alts)
  *wrapper* Cd_graph
    *prefix*
    (@
       adjacencies->collect_alternatives(c, svertex, alts);
    @)
  *wrapper* Adjacency_Nlist
    *prefix*
    (@
       Adjacency_list_iterator   next(*this);
       Adjacency*                each;

       while (each = next())
        {
           Vertex_list_iterator nextsuper(*each->get_superclasses());
           Vertex*              eachsuper;
           while (eachsuper = nextsuper())
              if (eachsuper->equal(svertex))
                 break;
           if (eachsuper)
           {
              if (c == NULL ||
                  !c->isXInhEdgeInTheList(each->get_source(), svertex))
              {
                 alts->append(each->get_source());
                 this->collect_alternatives(c,each->get_source(),alts);
              }
           }
        }
    @)

*operation* void collect_alternatives(Path_constraint_exp* c,
                                      Vertex*              svertex,
                                      Vertex_List*         alts,
                                      Adjacency_Nlist*     adjs)
  *wrapper*    Neighbors
    *prefix*
    (@
    @)
  *wrapper*    Neighbors_wc
    *prefix*
    (@
    @)
  *wrapper*    Alternat_ns
    *prefix*
    (@
      if (alternat_ns)
         alternat_ns->collect_alternatives(c, svertex, alts, adjs);
    @)
  *wrapper*   Term_Barlist
    *prefix*
    (@
       Term_list_iterator  next(*this);
       Term*               each;

       while (each = next())
         if (c == NULL ||
             !c->isXInhEdgeInTheList(each->get_vertex(), svertex))
           {
             alts->append(each->get_vertex());
             adjs->collect_alternatives(c, each->get_vertex(), alts);
           }
    @)