/*
* @(#)$Id: ChoiceState.java,v 1.5 2001/05/01 18:13:02 Bear Exp $
*
* Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
*
* This software is the proprietary information of Sun Microsystems, Inc.
* Use is subject to license terms.
*
*/
package com.sun.msv.reader;
import com.sun.msv.grammar.Expression;
/**
* state that creates ChoiceExp.
*
* @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
*/
public class ChoiceState extends ExpressionWithChildState {
public ChoiceState() {
this(false);
}
public ChoiceState( boolean allowEmptyChoice ) {
this.allowEmptyChoice = allowEmptyChoice;
}
protected boolean allowEmptyChoice;
protected Expression initialExpression() {
return allowEmptyChoice?Expression.nullSet:null;
}
protected Expression castExpression( Expression exp, Expression child ) {
// first one.
if( exp==null ) return child;
else return reader.pool.createChoice(exp,child);
}
}