/*---------------- FILE HEADER ------------------------------------------
This file is part of deegree.
Copyright (C) 2001-2006 by:
EXSE, Department of Geography, University of Bonn
http://www.giub.uni-bonn.de/deegree/
lat/lon GmbH
http://www.lat-lon.de
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; either
version 2.1 of the License, or (at your option) any later version.
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.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Contact:
Andreas Poth
lat/lon GmbH
Aennchenstr. 19
53115 Bonn
Germany
E-Mail: poth@lat-lon.de
Prof. Dr. Klaus Greve
Department of Geography
University of Bonn
Meckenheimer Allee 166
53115 Bonn
Germany
E-Mail: greve@giub.uni-bonn.de
---------------------------------------------------------------------------*/
package org.deegree.model.filterencoding;
import org.deegree.framework.xml.ElementList;
import org.deegree.framework.xml.XMLTools;
import org.deegree.model.feature.Feature;
import org.w3c.dom.Element;
/**
* Encapsulates the information of a <PropertyIsNull>-element (as defined in
* Filter DTD). The DTD defines the properties type to be tested as PropertyName
* or Literal.
*
* @author Markus Schneider
* @version 07.08.2002
*/
public class PropertyIsNullOperation extends ComparisonOperation {
private PropertyName propertyName;
public PropertyIsNullOperation(PropertyName propertyName) {
super(OperationDefines.PROPERTYISNULL);
this.propertyName = propertyName;
}
public PropertyName getPropertyName() {
return this.propertyName;
}
/**
* Given a DOM-fragment, a corresponding Operation-object is built. This
* method recursively calls other buildFromDOM () - methods to validate the
* structure of the DOM-fragment.
*
* @throws FilterConstructionException
* if the structure of the DOM-fragment is invalid
*/
public static Operation buildFromDOM(Element element)
throws FilterConstructionException {
// check if root element's name equals 'PropertyIsNull'
if (!element.getLocalName().equals("PropertyIsNull"))
throw new FilterConstructionException(
"Name of element does not equal 'PropertyIsNull'!");
ElementList children = XMLTools.getChildElements(element);
if (children.getLength() != 1)
throw new FilterConstructionException(
"'PropertyIsNull' requires exactly 1 element!");
Element child = children.item(0);
PropertyName propertyName = null;
switch (ExpressionDefines.getIdByName(child.getLocalName())) {
case ExpressionDefines.PROPERTYNAME: {
propertyName = (PropertyName) PropertyName.buildFromDOM( child );
break;
}
default: {
throw new FilterConstructionException(
"Name of element does not equal 'PropertyIsNull'!" );
}
}
return new PropertyIsNullOperation(propertyName);
}
/** Produces an indented XML representation of this object. */
public StringBuffer toXML() {
StringBuffer sb = new StringBuffer(500);
sb.append("<ogc:").append(getOperatorName()).append(">");
sb.append(propertyName.toXML());
sb.append("</ogc:").append(getOperatorName()).append(">");
return sb;
}
/**
* Calculates the <tt>PropertyIsNull</tt> -Operation's logical value based
* on the certain property values of the given <tt>Feature</tt>.
*
* @param feature
* that determines the property values
* @return true, if the <tt>PropertyIsNull</tt> -Operation evaluates to
* true, else false
* @throws FilterEvaluationException
* if the evaluation fails
*/
public boolean evaluate(Feature feature) throws FilterEvaluationException {
Object value = propertyName.evaluate(feature);
if (value == null) return true;
return false;
}
}/* ********************************************************************
Changes to this class. What the people have been up to:
$Log: PropertyIsNullOperation.java,v $
Revision 1.8 2006/07/12 14:46:14 poth
comment footer added
********************************************************************** */