Natools

   -----------------------
   -- Printer Interface --
   -----------------------

   overriding procedure Open_List (Output : in out Reference) is
   begin
      if Output.Exp.Is_Empty then
         Output.Exp.Replace (Create_Tree'Access);
      end if;

      Output.Exp.Update.Data.Append (List_Node);
   end Open_List;


   overriding procedure Append_Atom
     (Output : in out Reference; Data : in Atom) is
   begin
      if Output.Exp.Is_Empty then
         Output.Exp.Replace (Create_Tree'Access);
      end if;

      Output.Exp.Update.Data.Append (Atom_Node, new Atom'(Data));
   end Append_Atom;


   overriding procedure Close_List (Output : in out Reference) is
   begin
      if not Output.Exp.Is_Empty then
         Output.Exp.Update.Data.Close_List;
      end if;
   end Close_List;



   -------------------------
   -- Reading Subprograms --
   -------------------------