Str.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/Str.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: Str.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.UnaryFunction;
import org.openanzo.glitter.util.Glitter;
import org.openanzo.rdf.Literal;
import org.openanzo.rdf.MemPlainLiteral;
import org.openanzo.rdf.URI;
import org.openanzo.rdf.Value;
import org.openanzo.rdf.Constants.NAMESPACES;

/**
 * Implements <a href="http://www.w3.org/TR/rdf-sparql-query/#func-str">the SPARQL str function</a>.
 * @author lee <lee@cambridgesemantics.com>
 *
 */
public class Str extends UnaryFunction {

	@Override
	public Value call(Value arg1)
			throws IncompatibleTypeException {
		if (arg1 instanceof Literal) {
			return MemPlainLiteral.create(((Literal) arg1).getLabel());
		} else if (arg1 instanceof URI) {
			return MemPlainLiteral.create(((URI)arg1).toString());
		} else {
			throw new IncompatibleTypeException(arg1, "IRI reference or literal");
		}
	}

	public org.openanzo.rdf.URI getIdentifier() {
		return Glitter.createURI(NAMESPACES.BUILTIN_NAMESPACE + "str");
	}

}