Java Expressions and Assignments

public class NodeTerm extends Node { private NodeFact fact; private NodeMulop mulop; private NodeTerm term; public NodeTerm(NodeFact fact, NodeMulop mulop, NodeTerm term) { this.fact=fact; this.mulop=mulop; this.term=term; } public void append(NodeTerm term) { if (this.term==null) { this.mulop=term.mulop; this.term=term; term.mulop=null; } else this.term.append(term); } public int eval(Environment env) throws EvalException { return term==null ? fact.eval(env) : mulop.op(term.eval(env),fact.eval(env)); } }