FilterFunction_Convert.java

package org.geotools.filter.function;

/*
 *    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.
 */

import static org.geotools.filter.capability.FunctionNameImpl.parameter;

import org.geotools.filter.FunctionExpressionImpl;
import org.geotools.filter.capability.FunctionNameImpl;
import org.geotools.util.Converter;
import org.geotools.util.Converters;
import org.opengis.filter.capability.FunctionName;

/**
 * Applies the available {@link Converter} to turn the value into the desired target class 
 * @author Andrea Aime - GeoSolutions
 */
public class FilterFunction_Convert extends FunctionExpressionImpl {

    public static FunctionName NAME = new FunctionNameImpl("convert",
            parameter("converted", Object.class),
            parameter("value", Object.class),
            parameter("class", Class.class));

    public FilterFunction_Convert() {
        super(NAME);
    }

    public Object evaluate(Object feature) {
        try {
            Object arg = getExpression(0).evaluate(feature); 
            Class target = getExpression(1).evaluate(feature, Class.class);
            return Converters.convert(arg, target);
        } catch (Exception e) {
            throw new IllegalArgumentException(
                    "Filter Function problem for function convert argument #1 - expected type Class");
        }
    }
}