[Exist-commits] eXist-1.0/src/org/exist/xquery InstanceOfExpression.java,NONE,1.1

[Wolfgang M. M. <wol...@us...>]

Update of /cvsroot/exist/eXist-1.0/src/org/exist/xquery
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv10627/src/org/exist/xquery

Added Files:
	InstanceOfExpression.java 
Log Message:
Added support for "instance of" operator.

--- NEW FILE: InstanceOfExpression.java ---
/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-04 Wolfgang M. Meier
 *  wol...@ex...
 *  http://exist.sourceforge.net
 *  
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *  
 *  $Id: InstanceOfExpression.java,v 1.1 2004/06/18 12:07:27 wolfgang_m Exp $
 */
package org.exist.xquery;

import org.exist.xquery.value.BooleanValue;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

/**
 * Implements the XQuery "instance of" operator.
 * 
 * @author wolf
 */
public class InstanceOfExpression extends AbstractExpression {

	private Expression expression;
	private SequenceType type;
	
	/**
	 * @param context
	 */
	public InstanceOfExpression(XQueryContext context, Expression expr, SequenceType type) {
		super(context);
		this.expression = expr;
		this.type = type;
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#eval(org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
	 */
	public Sequence eval(Sequence contextSequence, Item contextItem)
			throws XPathException {
		Sequence seq = expression.eval(contextSequence, contextItem);
		int items = seq.getLength();
		int requiredCardinality = type.getCardinality();
		if(items > 0 && requiredCardinality == Cardinality.EMPTY)
			return BooleanValue.FALSE;
		if(items == 0 && (requiredCardinality & Cardinality.ZERO) == 0)
			return BooleanValue.FALSE;
		else if(items > 1 && (requiredCardinality & Cardinality.MANY) == 0)
			return BooleanValue.FALSE;
		
		for(SequenceIterator i = seq.iterate(); i.hasNext(); ) {
			Item next = i.nextItem();
			if(!Type.subTypeOf(next.getType(), type.getPrimaryType()))
				return BooleanValue.FALSE;
		}
		return BooleanValue.TRUE;
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#pprint()
	 */
	public String pprint() {
		return expression.pprint() + " instance of " + type.toString();
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#returnsType()
	 */
	public int returnsType() {
		return Type.BOOLEAN;
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.AbstractExpression#getCardinality()
	 */
	public int getCardinality() {
		return Cardinality.EXACTLY_ONE;
	}
	
	/* (non-Javadoc)
	 * @see org.exist.xquery.AbstractExpression#getDependencies()
	 */
	public int getDependencies() {
		return Dependency.CONTEXT_SET + Dependency.CONTEXT_ITEM;
	}
	
	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#resetState()
	 */
	public void resetState() {
		expression.resetState();
	}

}