/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2005-2008, 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.
*
* Created on May 11, 2005, 6:21 PM
*/
package org.geotools.filter.function;
import static org.geotools.filter.capability.FunctionNameImpl.parameter;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.feature.visitor.CalcResult;
import org.geotools.feature.visitor.SumVisitor;
import org.geotools.filter.FunctionExpressionImpl;
import org.geotools.filter.IllegalFilterException;
import org.geotools.filter.capability.FunctionNameImpl;
import org.opengis.filter.capability.FunctionName;
import org.opengis.filter.expression.Expression;
/**
* Calculates the sum value of an attribute for a given FeatureCollection
* and Expression.
*
* @author Cory Horner
* @since 2.2M2
*
*
* @source $URL$
*/
public class Collection_SumFunction extends FunctionExpressionImpl {
/** The logger for the filter module. */
private static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger(
"org.geotools.filter.function");
SimpleFeatureCollection previousFeatureCollection = null;
Object sum = null;
//public static FunctionName NAME = new FunctionNameImpl("Collection_Sum","expression");
public static FunctionName NAME = new FunctionNameImpl("Collection_Sum",
parameter("sum", Number.class),
parameter("expression", Number.class));
/**
* Creates a new instance of Collection_SumFunction
*/
public Collection_SumFunction() {
super(NAME);
}
/**
* Calculate sum (using FeatureCalc) - only one parameter is used.
*
* @param collection collection to calculate the sum
* @param expression Single Expression argument
*
* @return An object containing the sum value of the attributes
*
* @throws IllegalFilterException
* @throws IOException
*/
static CalcResult calculateSum(SimpleFeatureCollection collection,
Expression expression) throws IllegalFilterException, IOException {
SumVisitor sumVisitor = new SumVisitor(expression);
collection.accepts(sumVisitor, null);
return sumVisitor.getResult();
}
/**
* The provided arguments are evaulated with respect to the
* FeatureCollection.
*
* <p>
* For an aggregate function (like sum) please use the WFS mandated XPath
* syntax to refer to featureMember content.
* </p>
*
* <p>
* To refer to all 'X': <code>featureMember/asterisk/X</code>
* </p>
*
* @param args DOCUMENT ME!
*
* @throws IllegalArgumentException DOCUMENT ME!
*/
public void setParameters(List args) {
// if we see "featureMembers/*/ATTRIBUTE" change to "ATTRIBUTE"
org.opengis.filter.expression.Expression expr = (org.opengis.filter.expression.Expression) args.get(0);
expr = (org.opengis.filter.expression.Expression) expr.accept(new CollectionFeatureMemberFilterVisitor(),null);
args.set(0, expr );
super.setParameters(args);
}
public Object evaluate(Object feature) {
if (feature == null) {
return new Integer(0); // no features were visited in the making of this answer
}
SimpleFeatureCollection featureCollection = (SimpleFeatureCollection) feature;
Expression expr = (Expression) getExpression(0);
synchronized (featureCollection) {
if (featureCollection != previousFeatureCollection) {
previousFeatureCollection = featureCollection;
sum = null;
try {
CalcResult result = calculateSum(featureCollection, expr);
if (result != null) {
sum = result.getValue();
}
} catch (IllegalFilterException e) {
LOGGER.log(Level.FINER, e.getLocalizedMessage(), e);
} catch (IOException e) {
LOGGER.log(Level.FINER, e.getLocalizedMessage(), e);
}
}
}
return sum;
}
public void setExpression(Expression e) {
setParameters(Collections.singletonList(e));
}
}