/*
NeoDatis ODB : Native Object Database (odb.info@neodatis.org)
Copyright (C) 2007 NeoDatis Inc. http://www.neodatis.org

"This file is part of the NeoDatis ODB open source object database".

NeoDatis ODB 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 2.1 of the License, or (at your option) any later version.

NeoDatis ODB 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
package org.neodatis.odb.impl.core.query.criteria;

import org.neodatis.odb.core.layers.layer2.meta.AttributeValuesMap;
import org.neodatis.odb.core.query.criteria.AbstractCriterion;


public class IsNullCriterion extends AbstractCriterion {
	public IsNullCriterion(String attributeName) {
		super(attributeName);
	}

	public boolean match(Object valueToMatch) {
		
		// If it is a AttributeValuesMap, then gets the real value from the map
		if(valueToMatch instanceof AttributeValuesMap){
			AttributeValuesMap attributeValues = (AttributeValuesMap) valueToMatch;
			valueToMatch = attributeValues.get(attributeName);
		}
		
		return valueToMatch == null;
	}
	public AttributeValuesMap getValues() {
		return new AttributeValuesMap();
	}

	public void ready() {
	}

}