Subversion Repositories mkgmap

/*
 * Copyright (C) 2008 Steve Ratcliffe
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program 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 General Public License for more details.
 *
 *
 * Author: Steve Ratcliffe
 * Create date: 07-Dec-2008
 */
package uk.me.parabola.mkgmap.osmstyle.actions;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import uk.me.parabola.mkgmap.osmstyle.eval.UnitConversions;
import uk.me.parabola.mkgmap.reader.osm.Element;

/**
 * Convert a numeric quantity from one set of units to another.
 *
 * @author Steve Ratcliffe
 */
public class ConvertFilter extends ValueFilter {
        private static final Pattern UNIT_RE = Pattern.compile("\\s*([\\d.]+)\\s*([\\w/]*)\\s*");

        private final UnitConversions units;

        public ConvertFilter(String arg) {
                units = UnitConversions.createConversion(arg);
        }

        protected String doFilter(String value, Element el) {
                if (value == null || !units.isValid())
                        return value;

                String number = value;
                Double factor = units.getDefaultFactor();

                // If this is not a pure number, then extract the number part and the unit part
                // and convert based on the found values.  There are also various possible error
                // cases.
                if (!Character.isDigit(value.charAt(value.length() - 1))) {
                        // Extract number and unit string
                        Matcher matcher = UNIT_RE.matcher(value);
                        if (matcher.matches()) {
                                number = matcher.group(1);
                                String source = matcher.group(2);
                                factor = units.convertFactor(source);
                                if (factor == null)
                                        return value;
                        } else {
                                return value;
                        }
                }

                try {
                        double d = Double.parseDouble(number);
                        return String.valueOf(Math.round(d * factor));
                } catch (NumberFormatException e) {
                        // Turns out it wasn't a pure number, just return the value unchanged.
                        return value;
                }
        }
}