/*
 * @(#)$Id: AttributeFeeder.java,v 1.16 2001/10/18 23:52:17 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.verifier.regexp;

import com.sun.msv.grammar.*;
import org.xml.sax.Attributes;

/**
 * Feeds AttributeToken to the expression and obtains the residual (content model).
 * 
 * AttributeTokens are fed in order-less fashion.
 * 
 * @author <a href="mailto:kohsuke.kawaguchi@eng.sun.com">Kohsuke KAWAGUCHI</a>
 */
public class AttributeFeeder implements ExpressionVisitorExpression {
	protected final REDocumentDeclaration	docDecl;
	protected final ExpressionPool			pool;
	
	private Token							token;
		
	public AttributeFeeder( REDocumentDeclaration docDecl ) {
		this.docDecl	= docDecl;
		this.pool		= docDecl.pool;
	}

	
	public final Expression feed( Expression exp, AttributeToken token, boolean ignoreUndeclaredAttribute ) {
		this.token = token;
		Expression r = exp.visit(this);
		
		if(r!=Expression.nullSet || !ignoreUndeclaredAttribute)	return r;
		
		// if ignoreUndeclaredAttribute==true and expression is nullSet,
		// we have to check which of the following is the case.
		//   (1) attribute is undefined
		//   (2) value of the attribute was rejected.
		
		this.token = token.createRecoveryAttToken();
		r = exp.visit(this);
		
		// if wild card token is rejected, then it must be the absence of declaration.
		if(r==Expression.nullSet)	return exp;
		
		// otherwise the value was wrong.
		return Expression.nullSet;
		
//			if( com.sun.msv.driver.textui.Debug.debug )
//				System.out.println("after feeding "+atts.getQName(i)+" attribute");
//				System.out.println(com.sun.msv.grammar.trex.util.TREXPatternPrinter.printContentModel(exp));
	}
	

	public Expression onAttribute( AttributeExp exp ) {
		if( token.match(exp) )	return Expression.epsilon;
		else					return Expression.nullSet;
	}
	
//	/**
//	 * checks if the given expression is attribute-free.
//	 * 
//	 * if a expression is attribute free, then the residual must be nullSet.
//	 */
//	protected final boolean isAttributeFree( Expression exp ) {
//		Object o = exp.verifierTag;
//		return o!=null && ((OptimizationTag)o).isAttributeFree==Boolean.TRUE;
//	}
	
	public Expression onChoice( ChoiceExp exp ) {
//		if( isAttributeFree(exp) )	return Expression.nullSet;
		return pool.createChoice( exp.exp1.visit(this), exp.exp2.visit(this) );
	}
	public Expression onElement( ElementExp exp ) {
		return Expression.nullSet;
	}
	public Expression onOneOrMore( OneOrMoreExp exp ) {
//		if( isAttributeFree(exp) )	return Expression.nullSet;
		return pool.createSequence(
			exp.exp.visit(this),
			pool.createZeroOrMore(exp.exp) );
	}
	public Expression onMixed( MixedExp exp ) {
		return pool.createMixed( exp.exp.visit(this) );
	}
	public Expression onList( ListExp exp ) {
		return Expression.nullSet;
	}
	public Expression onEpsilon()		{ return Expression.nullSet; }
	public Expression onNullSet()		{ return Expression.nullSet; }
	public Expression onAnyString()		{ return Expression.nullSet; }
	public Expression onRef( ReferenceExp exp ) {
		return exp.exp.visit(this);
	}
	public Expression onOther( OtherExp exp ) {
		return exp.exp.visit(this);
	}
	public Expression onSequence( SequenceExp exp ) {
//		if( isAttributeFree(exp) )	return Expression.nullSet;
		// for attributes only, sequence acts as orderless
		return pool.createChoice(
			pool.createSequence( exp.exp1.visit(this), exp.exp2 ),
			pool.createSequence( exp.exp1, exp.exp2.visit(this) ) );
	}
	public Expression onData( DataExp exp ) {
		return Expression.nullSet;
	}
	public Expression onValue( ValueExp exp ) {
		return Expression.nullSet;
	}
	public Expression onConcur( ConcurExp exp ) {
		return pool.createConcur( exp.exp1.visit(this), exp.exp2.visit(this) );
	}
	public Expression onInterleave( InterleaveExp exp ) {
		return pool.createChoice(
			pool.createInterleave( exp.exp1.visit(this), exp.exp2 ),
			pool.createInterleave( exp.exp1, exp.exp2.visit(this) ) );
	}

}