Not.java

/******************************************************************************* 
 * Copyright (c) 2004, 2007 IBM Corporation and Cambridge Semantics Incorporated.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0 
 * which accompanies this distribution, and is available at 
 * http://www.eclipse.org/legal/epl-v10.html 
 * 
 * File: $Source: /cvsroot/slrp/glitter/com.ibm.adtech.glitter/src/com/ibm/adtech/glitter/expression/builtin/Not.java,v $
 * Created by:  Lee Feigenbaum (<a href="mailto:feigenbl@us.ibm.com">feigenbl@us.ibm.com</a>) 
 * Created on: 10/23/06
 * Revision: $Id: Not.java 164 2007-07-31 14:11:09Z mroy $
 *  
 * Contributors: IBM Corporation - initial API and implementation 
 *     Cambridge Semantics Incorporated - Fork to Anzo
 *******************************************************************************/
package org.openanzo.glitter.expression.builtin;

import org.openanzo.glitter.exception.IncompatibleTypeException;
import org.openanzo.glitter.expression.PrefixOperator;
import org.openanzo.glitter.expression.UnaryFunction;
import org.openanzo.glitter.util.Constants;
import org.openanzo.glitter.util.Glitter;
import org.openanzo.glitter.util.TypeConversions;
import org.openanzo.rdf.URI;
import org.openanzo.rdf.Value;
import org.openanzo.rdf.Constants.NAMESPACES;

/**
 * Tri-state (including errors) logical-not operator (!).
 * @author lee <lee@cambridgesemantics.com>
 *
 */
public class Not extends UnaryFunction implements PrefixOperator {

	@Override
	public Value call(Value arg1) throws IncompatibleTypeException {
		return (
			!TypeConversions.effectiveBooleanValue(arg1)
		)?Constants.TRUE:Constants.FALSE;
	}

	public URI getIdentifier() {
		return Glitter.createURI(NAMESPACES.FN_NAMESPACE + "not");
	}

    public String getOperator() {
        return "!";
    }

}