bytecomparable.java

实现数据库的storage manager 功能

/*
 * Copyright (c) 2000-2004, Rickard C鰏ter, Martin Svensson
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, 
 * this list of conditions and the following disclaimer. 
 * Redistributions in binary form must reproduce the above copyright notice, 
 * this list of conditions and the following disclaimer in the documentation 
 * and/or other materials provided with the distribution. 
 * Neither the name of SICS nor the names of its contributors 
 * may be used to endorse or promote products derived from this software 
 * without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
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 */

package com.mellowtech.disc;
import java.nio.ByteBuffer;

/**
 * ByteStore objects that are able to be compared on
 * a byte level should implement this interface. This
 * allows for comparison of ByteStorables without first
 * converting them from their byte representation. This allows for, 
 * for instance, disc based sorting to be done much more rapidly.
 *
 * @author Martin Svensson
 * @version 1.0
 * @see com.mellowtech.disc.ByteStorable
 */
public interface ByteComparable{
  
  /**
   * Compares two objects that are represented as
   * bytes in a ByteBuffer.
   *
   * @param offset1 the offset in the buffer for the first object
   * @param offset2 the offset in the buffer for the second object
   * @param bb the buffer that holds the object
   * @return a negative integer, zero, or a positive integer as 
   * the first argument is less than, equal to, or greater than the second.
   */
  public int byteCompare(int offset1, int offset2, ByteBuffer bb);

   /**
   * Compares two objects that are represented as
   * bytes in a byte array.
   *
   * @param offset1 the offset in the buffer for the first object
   * @param offset2 the offset in the buffer for the second object
   * @param b the buffer that holds the object
   * @return a negative integer, zero, or a positive integer as the 
   * first argument is less than, equal to, or greater than the second.
   */
  public int byteCompare(int offset1, int offset2, byte[] b);
}