abstract  void process(Env<AttrContext> env)

  void run(Queue<AttrContext> list,
    Iterable<TypeElement> classes) 
{
            Set< TypeElement > set = new HashSet< TypeElement >();
            for (TypeElement item: classes)
                set.add(item);
            ListBuffer< Env< AttrContext > > defer = ListBuffer.< Env< AttrContext > >lb();
            while (list.peek() != null) {
                Env< AttrContext > env = list.remove();
                ClassSymbol csym = env.enclClass.sym;
                if (csym != null && set.contains(csym.outermostClass()))
                    process(env);
                else
                    defer = defer.append(env);
            }
            list.addAll(defer);
}