/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library 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;
* version 2.1 of the License.
*
* This library 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.
*/
package org.geotools.filter.expression;
import org.geotools.factory.Hints;
/**
* This class supports the use of Expression/NIL for referring to a 'null' value.
*
* @author Niels Charlier, Curtin University Of Technology
*
*
* @source $URL: http://svn.osgeo.org/geotools/trunk/modules/library/main/src/main/java/org/geotools/filter/expression/NullPropertyAccessorFactory.java $
* http://svn.osgeo.org/geotools/trunk/modules/library/main/src/main/java/org/geotools/
* filter/expression/NullPropertyAccessorFactory.java $
*/
public class NullPropertyAccessorFactory implements PropertyAccessorFactory {
static private PropertyAccessor NULLPA = new NullPropertyAccessor();
public PropertyAccessor createPropertyAccessor(Class type, String xpath, Class target,
Hints hints) {
return NULLPA;
}
/**
* Return null for Expression/NIL
*
* @author Niels Charlier, CSIRO
*/
static class NullPropertyAccessor implements PropertyAccessor {
/**
* We can handle *one* case and one case only
*/
public boolean canHandle(Object object, String xpath, Class target) {
return "Expression/NIL".equals(xpath); // case sensitive
}
public Object get(Object object, String xpath, Class target)
throws IllegalArgumentException {
return null;
}
public void set(Object object, String xpath, Object value, Class target)
throws IllegalArgumentException {
throw new IllegalArgumentException("Cannot assign a value to Expression/NIL.");
}
}
}