/*******************************************************************************
* 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/Bound.java,v $
* Created by: Lee Feigenbaum ( <a href="mailto:feigenbl@us.ibm.com">feigenbl@us.ibm.com </a>)
* Created on: 10/23/2006
* Revision: $Id: Bound.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.function;
import java.util.List;
import org.openanzo.glitter.exception.IncompatibleTypeException;
import org.openanzo.glitter.exception.InvalidArgumentCountException;
import org.openanzo.glitter.expression.ScalarFunctionOnTerms;
import org.openanzo.glitter.query.PatternSolution;
import org.openanzo.glitter.syntax.abstrakt.Expression;
import org.openanzo.glitter.util.Glitter;
import org.openanzo.rdf.URI;
import org.openanzo.rdf.Value;
import org.openanzo.rdf.ValueMax;
import org.openanzo.rdf.Constants.NAMESPACES;
/**
* Implements a Glitter funciton that treats unbound values as the maximum possible value for the purpose of sorting.
*
* @author lee <lee@cambridgesemantics.com>
*
*/
public class UnboundAsMaxValue implements ScalarFunctionOnTerms {
public Value call(List<Expression> args, PatternSolution environment) throws IncompatibleTypeException, InvalidArgumentCountException {
if (args.size() != 1)
throw new InvalidArgumentCountException(args.size(), 1);
Expression arg = args.get(0);
Value v = arg.evaluate(environment, null);
if (v == null)
return ValueMax.getInstance();
return v;
}
public URI getIdentifier() {
return Glitter.createURI(NAMESPACES.GLITTER_FUNCTION_NAMESPACE + "unboundAsMaxValue");
}
public boolean operatesOnValues() {
return false;
}
public boolean operatesOnTypeErrors() {
return false;
}
@Override
public String toString() {
return getIdentifier().getLocalName();
}
}