org.opengis.filter.PropertyIsNil Maven / Gradle / Ivy

/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2011, Open Source Geospatial Foundation (OSGeo)
 *    (C) 2005 Open Geospatial Consortium Inc.
 *
 *    All Rights Reserved. http://www.opengis.org/legal/
 */
package org.opengis.filter;

// OpenGIS direct dependencies

import org.opengis.annotation.XmlElement;
import org.opengis.filter.expression.Expression;

/**
 * Filter operator that checks if an expression's value is nil.
 *
 * From the specification: 
 *
 * 
 * The PropertyIsNil operator tests the content of the specified property and evaluates if it is nil.
 * The operator can also evaluate the nil reason using the nilReason parameter. The implied operator
 * for evaluating the nil reason is "equals".
 * 

 *
 * 
 *
 * @author Justin Deoliveira, OpenGeo
 * @see http://portal.opengeospatial.org/files/?artifact_id=39968
 * @since GeoAPI 2.0
 */
@XmlElement("PropertyIsNil")
public interface PropertyIsNil extends Filter {
    /** Operator name used to check FilterCapabilities */
    public static String NAME = "Nil";

    /** Returns the expression whose value will be checked for {@code null}. */
    @XmlElement("expression")
    Expression getExpression();

    /** The nil reason. */
    @XmlElement("nilReason")
    Object getNilReason();
}