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: 09-Nov-2008
 */
package uk.me.parabola.mkgmap.osmstyle.eval;

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


/**
 * Represents a number and the units it is in. We want ultimately to be
 * able to do things like: is 10km/h > 8mph, and get the right answer
 * by converting to a common unit.
 *
 * To start with we will just compare the numbers.
 *
 * @author Steve Ratcliffe
 */
public class ValueWithUnit implements Comparable<ValueWithUnit> {
        private static final Pattern EXTRACT_NUMBER_UNIT
                        = Pattern.compile("[ \t]*(-?[0-9.]+)[ \t]*(.*)");
        private static final BigDecimal ZERO = new BigDecimal(0);

        private final BigDecimal value;
        private final String unit;

        private final boolean valid;

        public ValueWithUnit(String val) {
                Matcher m = EXTRACT_NUMBER_UNIT.matcher(val);
                boolean found = m.find();

                BigDecimal value = ZERO;
                String unit = "";
                boolean ok = false;

                if (found) {
                        try {
                                value = new BigDecimal(m.group(1));
                                unit = m.group(2).trim();
                                ok = true;
                        } catch (NumberFormatException e) {
                                ok = false;
                        }
                }
               
                this.value = value;
                this.unit = unit;
                this.valid = ok;
        }

        /**
         * Compares this object with the specified object for order. Returns
         * a negative integer, zero, or a positive integer as this object
         * is less than, equal to, or greater than the specified object.
         *
         * To start with, just compare the value and ignore the unit.
         */
        public int compareTo(ValueWithUnit o) {
                return value.compareTo(o.value);
        }

        public boolean isValid() {
                return valid;
        }

        public String toString() {
                return value + unit;
        }
}