jetty-start/src/main/java/org/eclipse/jetty/start/Version.java

//
//  ========================================================================
//  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.start;

/**
 * Utility class for parsing and comparing version strings. JDK 1.1 compatible.
 * 
 */

public class Version
{

    int _version = 0;
    int _revision = 0;
    int _subrevision = 0;
    String _suffix = "";

    public Version()
    {
    }

    public Version(String version_string)
    {
        parse(version_string);
    }

    // java.lang.Comparable is Java 1.2! Cannot use it
    /**
     * Compares with other version. Does not take extension into account, as there is no reliable way to order them.
     * 
     * @return -1 if this is older version that other, 0 if its same version, 1 if it's newer version than other
     */
    public int compare(Version other)
    {
        if (other == null)
        {
            throw new NullPointerException("other version is null");
        }
        if (this._version < other._version)
        {
            return -1;
        }
        if (this._version > other._version)
        {
            return 1;
        }
        if (this._revision < other._revision)
        {
            return -1;
        }
        if (this._revision > other._revision)
        {
            return 1;
        }
        if (this._subrevision < other._subrevision)
        {
            return -1;
        }
        if (this._subrevision > other._subrevision)
        {
            return 1;
        }
        return 0;
    }

    /**
     * Check whether this verion is in range of versions specified
     */
    public boolean isInRange(Version low, Version high)
    {
        return ((compare(low) >= 0) && (compare(high) <= 0));
    }

    /**
     * parses version string in the form version[.revision[.subrevision[extension]]] into this instance.
     */
    public void parse(String version_string)
    {
        _version = 0;
        _revision = 0;
        _subrevision = 0;
        _suffix = "";
        int pos = 0;
        int startpos = 0;
        int endpos = version_string.length();
        while ((pos < endpos) && Character.isDigit(version_string.charAt(pos)))
        {
            pos++;
        }
        _version = Integer.parseInt(version_string.substring(startpos,pos));
        if ((pos < endpos) && (version_string.charAt(pos) == '.'))
        {
            startpos = ++pos;
            while ((pos < endpos) && Character.isDigit(version_string.charAt(pos)))
            {
                pos++;
            }
            _revision = Integer.parseInt(version_string.substring(startpos,pos));
        }
        if ((pos < endpos) && (version_string.charAt(pos) == '.'))
        {
            startpos = ++pos;
            while ((pos < endpos) && Character.isDigit(version_string.charAt(pos)))
            {
                pos++;
            }
            _subrevision = Integer.parseInt(version_string.substring(startpos,pos));
        }
        if (pos < endpos)
        {
            _suffix = version_string.substring(pos);
        }
    }

    /**
     * @return string representation of this version
     */
    @Override
    public String toString()
    {
        StringBuffer sb = new StringBuffer(10);
        sb.append(_version);
        sb.append('.');
        sb.append(_revision);
        sb.append('.');
        sb.append(_subrevision);
        sb.append(_suffix);
        return sb.toString();
    }
}