// $Id: Visitor.java,v 1.1 1999/11/15 05:26:53 leavens Exp $

package lib.atomic_expression;

/** A top-level visitor interface for AtomicExpressions.
 * @see ToString
 * @see CountLeaves
 **/
public interface Visitor {
    /** visit a Nil atomic expression **/
    Object visitNil(Nil n);
    /** visit an Atom atomic expression **/
    Object visitAtom(Atom a);
    /** visit an Expr atomic expression **/
    Object visitExpr(Expr e);
}