broker-core/src/main/java/org/apache/qpid/server/util/Serial.java

/*
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * 
 */
package org.apache.qpid.server.util;


import java.util.Comparator;

/**
 * This class provides basic serial number comparisons as defined in
 * RFC 1982.
 */

public class Serial
{
    private Serial()
    {
    }

    public static final Comparator<Integer> COMPARATOR = new Comparator<Integer>()
    {
        @Override
        public int compare(Integer s1, Integer s2)
        {
            return Serial.compare(s1, s2);
        }
    };

    /**
     * Compares two numbers using serial arithmetic.
     *
     * @param s1 the first serial number
     * @param s2 the second serial number
     *
     * @return a negative integer, zero, or a positive integer as the
     * first argument is less than, equal to, or greater than the
     * second
     */
    public static final int compare(int s1, int s2)
    {
        return s1 - s2;
    }

    public static final boolean lt(int s1, int s2)
    {
        return compare(s1, s2) < 0;
    }

    public static final boolean le(int s1, int s2)
    {
        return compare(s1, s2) <= 0;
    }

    public static final boolean gt(int s1, int s2)
    {
        return compare(s1, s2) > 0;
    }

    public static final boolean ge(int s1, int s2)
    {
        return compare(s1, s2) >= 0;
    }

    public static final boolean eq(int s1, int s2)
    {
        return s1 == s2;
    }

    public static final int min(int s1, int s2)
    {
        if (lt(s1, s2))
        {
            return s1;
        }
        else
        {
            return s2;
        }
    }

    public static final int max(int s1, int s2)
    {
        if (gt(s1, s2))
        {
            return s1;
        }
        else
        {
            return s2;
        }
    }

}