FilterFunction_numberFormat2.java

/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2005-2010, 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.function;

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

import org.geotools.filter.FunctionExpressionImpl;
import org.geotools.filter.capability.FunctionNameImpl;
import org.opengis.filter.capability.FunctionName;

/**
 * Formats a number into a string given a certain pattern (specified in the format accepted
 * by {@link DecimalFormat}} 
 * <p>
 * This function expands on {@link FilterFunction_numberFormat} and adds some additonal parameters 
 * such as allowing the user to explicitly specify the decimal and group separators, rather than 
 * falling back on locale based defaults. 
 * </p>
 * @author Justin Deoliveira, OpenGeo
 * 
 *
 * @source $URL: http://svn.osgeo.org/geotools/trunk/modules/library/main/src/main/java/org/geotools/filter/function/FilterFunction_numberFormat2.java $
 */
public class FilterFunction_numberFormat2 extends FunctionExpressionImpl {
    public static FunctionName NAME = new FunctionNameImpl("numberFormat2","format","number","minus","decimal","seperator");
    public FilterFunction_numberFormat2() {
        super("numberFormat2");
        functionName = NAME;
    }

    @Override
    public int getArgCount() {
        return 5;
    }
    
    public Object evaluate(Object feature) {
        String format;
        Double number;

        try {
            // attempt to get value and perform conversion
            format  = getExpression(0).evaluate(feature, String.class);
        } catch (Exception e) // probably a type error
        {
            throw new IllegalArgumentException(
                    "Filter Function problem for function dateFormat argument #0 - expected type String");
        }

        try { // attempt to get value and perform conversion
            number = getExpression(1).evaluate(feature, Double.class); 
        } catch (Exception e) // probably a type error
        {
            throw new IllegalArgumentException(
                    "Filter Function problem for function dateFormat argument #1 - expected type java.util.Date");
        }

        DecimalFormatSymbols symbols = new DecimalFormatSymbols();
        
        if (params.size() > 2) {
            Character neg = getExpression(2).evaluate(feature, Character.class);
            symbols.setMinusSign(neg);
        }
        
        if (params.size() > 3) {
            Character dec = getExpression(3).evaluate(feature, Character.class);
            symbols.setDecimalSeparator(dec);
        }
        
        if (params.size() > 4) {
            Character grp = getExpression(4).evaluate(feature, Character.class);
            symbols.setGroupingSeparator(grp);
        }
        
        DecimalFormat numberFormat = new DecimalFormat(format, symbols);
        return numberFormat.format(number);
    }
}