ExpressionPrinter.java

/*
 * @(#)$Id: ExpressionPrinter.java,v 1.16 2001/10/18 23:52:11 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.grammar.util;

import com.sun.msv.grammar.*;

/**
 * creates a string representation of the expression.
 * 
 * useful for debug and dump.
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
 */
public class ExpressionPrinter implements ExpressionVisitor {
	
	
	/** in this mode, reference to other expression is
	 * one of the terminal symbol of stringnization.
	 * 
	 * Suitable to dump the entire grammar
	 */
	public final static int FRAGMENT = 0x001;
	
	/** in this mode, element declaration is
	 * one of the terminal symbol of stringnization.
	 * 
	 * Suitable to dump the content model of element declarations.
	 */
	public final static int CONTENTMODEL = 0x002;

	
	
	// singleton access
	public static ExpressionPrinter fragmentInstance = new ExpressionPrinter(FRAGMENT);
	public static ExpressionPrinter contentModelInstance = new ExpressionPrinter(CONTENTMODEL);
	public static ExpressionPrinter smallestInstance = new ExpressionPrinter(CONTENTMODEL|FRAGMENT);
	
	public static String printFragment(Expression exp) {
		return (String)exp.visit(fragmentInstance);
	}
	public static String printContentModel(Expression exp) {
		return (String)exp.visit(contentModelInstance);
	}
	public static String printSmallest(Expression exp) {
		return (String)exp.visit(smallestInstance);
	}
	
	
	/** this flag controls how expression will be stringnized */
	protected final int mode;
	
	protected ExpressionPrinter( int mode ) { this.mode = mode; }
	
	/** dumps all the contents of ReferenceContainer.
	 * 
	 * this method is a useful piece to dump the entire grammar.
	 */
	public String printRefContainer( ReferenceContainer cont ) {
		String r="";
		java.util.Iterator itr = cont.iterator();
		while( itr.hasNext() ) {
			ReferenceExp exp = (ReferenceExp)itr.next();
			
			r += exp.name + "  : " + exp.exp.visit(this) + "\n";
		}
		return r;
	}
	
	/** determines whether brackets should be used to represent the pattern */
	protected static boolean isComplex( Expression exp ) {
		return exp instanceof BinaryExp;
	}
	
	protected String printBinary( BinaryExp exp, String op ) {
		String r;
		
		if( exp.exp1.getClass()==exp.getClass() || !isComplex(exp.exp1) )
			r = (String)exp.exp1.visit(this);
		else
			r = "("+exp.exp1.visit(this)+")";

		r+=op;
		
		if( !isComplex(exp.exp2) )
				r+=exp.exp2.visit(this);
		else
				r+="("+exp.exp2.visit(this)+")";
		
		return r;
	}
	
	public Object onAttribute( AttributeExp exp ) {
		return "@"+exp.nameClass.toString()+"<"+exp.exp.visit(this)+">";
	}
	
	private Object optional( Expression exp ) {
		if( exp instanceof OneOrMoreExp ) {
			OneOrMoreExp ome = (OneOrMoreExp)exp;
			if( isComplex(ome.exp) )	return "("+ome.exp.visit(this)+")*";
			else						return ome.exp.visit(this)+"*";
		} else {
			if( isComplex(exp) )	return "("+exp.visit(this)+")?";
			else					return exp.visit(this)+"?";
		}
	}
	
	public Object onChoice( ChoiceExp exp )	 {
		if( exp.exp1==Expression.epsilon )	return optional(exp.exp2);
		if( exp.exp2==Expression.epsilon )	return optional(exp.exp1);
			
		return printBinary(exp,"|");
	}

	public Object onConcur( ConcurExp exp ) {
		return printBinary(exp,"&");
	}
	public Object onInterleave( InterleaveExp exp ){
		return printBinary(exp,"^");
	}
	
	public Object onElement( ElementExp exp ) {
		if( (mode&CONTENTMODEL)!=0 )
			return exp.getNameClass().toString();
		else
			return exp.getNameClass().toString()+"<"+exp.contentModel.visit(this)+">";
	}
	
	public Object onOneOrMore( OneOrMoreExp exp ) {
		if( isComplex(exp.exp) )	return "("+exp.exp.visit(this)+")+";
		else						return exp.exp.visit(this)+"+";
	}
	
	public Object onMixed( MixedExp exp ) {
		return "mixed["+exp.exp.visit(this)+"]";
	}
	
	public Object onList( ListExp exp ) {
		return "list["+exp.exp.visit(this)+"]";
	}
	
	public Object onEpsilon() {
		return "#epsilon";
	}
	
	public Object onNullSet() {
		return "#nullSet";
	}
	
	public Object onAnyString() {
		return "<anyString>";
	}
	
	public Object onSequence( SequenceExp exp )	{
		return printBinary(exp,",");
	}
	
	public Object onData( DataExp exp ) {
		return "$"+exp.name.localName;
	}	

	public Object onValue( ValueExp exp ) {
		return "$$"+exp.value;
	}	
	
	public Object onOther( OtherExp exp ) {
		
		return exp.printName()+"["+exp.exp.visit(this)+"]";
	}
		
	public Object onRef( ReferenceExp exp ) {
		if( (mode&FRAGMENT)!=0 )		return "{%"+exp.name+"}";
		else							return "("+exp.exp.visit(this)+")";
	}
}