/*
 * @(#)$Id: RootState.java,v 1.15 2001/10/12 01:37:30 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.trex;

import com.sun.msv.grammar.Expression;
import com.sun.msv.reader.State;
import com.sun.msv.reader.SimpleState;
import com.sun.msv.util.StartTagInfo;
import com.sun.msv.grammar.trex.TREXGrammar;

/**
 * invokes State object that parses the document element.
 * 
 * This class is used to parse the first grammar.
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
 */
public class RootState extends RootIncludedPatternState {
	
	public RootState() { super(null); }

	protected State createChildState( StartTagInfo tag ) {
		// grammar has to be treated separately so as not to
		// create unnecessary TREXGrammar object.
		if(tag.localName.equals("grammar"))
			return new GrammarState();
		
		State s = super.createChildState(tag);
		if(s!=null) {
			// other pattern element is specified.
			// create wrapper grammar
			final TREXBaseReader reader = (TREXBaseReader)this.reader;
			reader.grammar = reader.sfactory.createGrammar( reader.pool, null );
			simple = true;
		}
		
		return s;
	}
	
	/**
	 * a flag that indicates 'grammar' element was not used.
	 * In that case, this object is responsible to set start pattern.
	 */
	private boolean simple = false;
		
	// GrammarState implements ExpressionState,
	// so RootState has to implement ExpressionOwner.
	public void onEndChild(Expression exp) {
		super.onEndChild(exp);

		final TREXBaseReader reader = (TREXBaseReader)this.reader;

		if( simple )
			// set the top-level expression if that is necessary.
			reader.grammar.exp = exp;
		
		// perform final wrap-up.
		reader.wrapUp();
	}
}