UUID tests.

[Sven de Marothy <sven at physto dot se>]

I commited a java.util.UUID impl.

Here's a full set of tests (AFAIK), we pass them all.

/Sven

/* UUID.java -- Class that represents a UUID object.
   Copyright (C) 2006  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
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permission to link this library with independent modules to produce an
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package java.util;

import java.io.Serializable;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * This class represents a 128-bit UUID value.
 * 
 * There are several types of UUID, and while this class can be used to store
 * them, only the Leach-Salz (variant 2) UUID specified in RFC-4122 will 
 * give meaningful results from the method calls.
 * See: http://tools.ietf.org/html/4122 for the details
 *
 * The format of a Leach-Salz (variant 2) time-based (version 1) UUID 
 * is as follows:
 * time_low - upper 32 bits of the most significant 64 bits,
 *            this is the least-significant part of the timestamp.
 *
 * time_mid - bits 16-31 of the most significant 64 bits,
 *            this is the middle portion of the timestamp. 
 *
 * version  - bits 8-15 of the most significant 64 bits. 
 *
 * time_hi  - bits 0-7 of the most significant 64 bits,
 *            the most significant portion of the timestamp.
 *
 * clock_and_reserved  - bits 48-63 of the least significant 64 bits.
 *                       a variable number of bits hold the variant 
 *                       (see the spec)
 * 
 * node identifier     - bits 0-47 of the least signficant 64 bits.
 *
 * These fields are valid only for version 1, in the remaining versions,
 * only the version and variant fields are set, all others are used for data.
 *
 * @since 1.5
 * @author Sven de Marothy
 */
public final class UUID extends Object implements Serializable, Comparable
{
  private static final long serialVersionUID = -4856846361193249489L;

  /**
   * Serialized field - most significant 64 bits.
   */
  private long mostSigBits;

  /**
   * Serialized field - least significant 64 bits.
   */
  private long leastSigBits;

  /**
   * Random-number generator.
   */
  private static transient Random r = new Random();

  /**
   * Constructs a new UUID.
   *
   * @since 1.5
   */
  public UUID(long mostSigBits, long leastSigBits)
  {
    this.mostSigBits = mostSigBits;
    this.leastSigBits = leastSigBits;
  }
 
  /**
   * Returns the clock-sequence value of this UUID.
   * This field only exists in a time-based (version 1) UUID.
   *
   * @throws UnsupportedOperationException if the UUID type is not 1.
   * @returns an int containing the clock-sequence value.
   */
  public int clockSequence()
  {
    if( version() != 1 )
      throw new UnsupportedOperationException("Not a type 1 UUID");
    return (int)((leastSigBits & 0x3FFF000000000000L) >> 48);
  }

  /**
   * Compare this UUID to another.
   * The comparison is performed as between two 128-bit integers.
   *
   * @return -1 if this < val, 0 if they are equal, 1 if this > val.
   */
  public int compareTo(Object val)
  {
    UUID o = (UUID)val; // genericizeme!
    if( mostSigBits < o.mostSigBits )
      return -1;
    if( mostSigBits > o.mostSigBits )
      return 1;
    if( leastSigBits < o.leastSigBits )
      return -1;
    if( leastSigBits > o.mostSigBits )
      return 1;
    return 0;
  }

  /**
   * Compare a (UUID) object to this one
   */
  public boolean equals(Object obj)
  {
    if( !(obj instanceof UUID ) )
      return false;
    return ( ((UUID)obj).mostSigBits == mostSigBits && 
	     ((UUID)obj).leastSigBits == leastSigBits );
  }

  /**
   * Creates a UUID object from a Sting representation.
   *
   * For the format of the string,
   * @see #toString()
   *
   * @return a new UUID object.
   */
  public static UUID fromString(String name)
  {
    StringTokenizer st = new StringTokenizer( name.trim(), "-" );
    if( st.countTokens() < 5 )
      throw new IllegalArgumentException( "Incorrect UUID string"+
					  " representation:"+name );

    long msb = (Long.parseLong(st.nextToken(), 16) << 32); // time low
    msb |= (Long.parseLong(st.nextToken(), 16) << 16); // time mid
    msb |= Long.parseLong(st.nextToken(), 16); // time high

    long lsb = (Long.parseLong(st.nextToken(), 16) << 48); // clock
    lsb |= Long.parseLong(st.nextToken(), 16); // node

    return new UUID(msb, lsb);
  }

  /**
   * Returns a String representation of the UUID.
   *
   * The format of the standard string representation (given in RFC4122) is:
   *
   * time-low "-" time-mid "-"
   * time-high-and-version "-"
   * clock-seq-and-reserved
   * clock-seq-low "-" node
   *
   * Where each field is represented as a hex string.
   *
   * @return the String representation.
   */
  public String toString()
  {
    return // time-low first
      padHex( (( mostSigBits & 0xFFFFFFFF00000000L) >> 32) & 0xFFFFFFFFL, 8)
      + "-" + // then time-mid
      padHex( (( mostSigBits & 0xFFFF0000L ) >> 16), 4 ) 
      + "-" + // time-high
      padHex( ( mostSigBits & 0x0000000000000000FFFFL ), 4 ) 
      + "-" + // clock (note - no reason to separate high and low here)
      padHex( (((leastSigBits & 0xFFFF000000000000L) >> 48) & 0xFFFF), 4 ) 
      + "-" + // finally the node value.
      padHex(leastSigBits & 0xFFFFFFFFFFFFL, 12); 
  }

  /**
   * Returns the least significant 64 bits of the UUID as a <code>long</code>.
   */ 
  public long getLeastSignificantBits()
  {
    return leastSigBits;
  }

  /**
   * Returns the most significant 64 bits of the UUID as a <code>long</code>.
   */ 
  public long getMostSignificantBits()
  {
    return mostSigBits;
  }

  /**
   * Returns a hash of this UUID.
   */
  public int hashCode()
  {
    int l1 = (int)(leastSigBits & 0xFFFFFFFFL);
    int l2 = (int)((leastSigBits & 0xFFFFFFFF00000000L) >> 32);
    int m1 = (int)(mostSigBits & 0xFFFFFFFFL);
    int m2 = (int)((mostSigBits & 0xFFFFFFFF00000000L) >> 32);

    return (l1 ^ l2) ^ (m1 ^ m2);
  }

  /**
   * Creates a UUID version 3 object (name based with MD5 hashing)
   * from a series of bytes representing a name.
   */
  public static UUID nameUUIDFromBytes(byte[] name)
  {    
    long msb, lsb;
    byte[] hash;

    try
      {
	MessageDigest md5 = MessageDigest.getInstance("MD5");
	hash = md5.digest( name );
      } 
    catch (NoSuchAlgorithmException e) 
      {
	throw new UnsupportedOperationException("No MD5 algorithm available.");
      }
	
    msb = ((hash[0] & 0xFFL) << 56) | ((hash[1] & 0xFFL) << 48) |
      ((hash[2] & 0xFFL) << 40) | ((hash[3] & 0xFFL) << 32) |
      ((hash[4] & 0xFFL) << 24) | ((hash[5] & 0xFFL) << 16) |
      ((hash[6] & 0xFFL) << 8) | (hash[7] & 0xFFL);

    lsb = ((hash[8] & 0xFFL) << 56) | ((hash[9] & 0xFFL) << 48) |
      ((hash[10] & 0xFFL) << 40) | ((hash[11] & 0xFFL) << 32) |
      ((hash[12] & 0xFFL) << 24) | ((hash[13] & 0xFFL) << 16) |
      ((hash[14] & 0xFFL) << 8) | (hash[15] & 0xFFL);

    lsb &= 0x3FFFFFFFFFFFFFFFL; 
    lsb |= 0x8000000000000000L; // set top two bits to variant 2

    msb &= 0xFFFFFFFFFFFF0FFFL; 
    msb |= 0x3000; // Version 3; 

    return new UUID(msb, lsb);
  }

  /**
   * Returns the 48-bit node value in a long. 
   * This field only exists in a time-based (version 1) UUID.
   *
   * @throws UnsupportedOperationException if the UUID type is not 1.
   * @returns a long with the node value in the lower 48 bits.
   */
  public long node() 
  {
    if( version() != 1 )
      throw new UnsupportedOperationException("Not a type 1 UUID");
    return (leastSigBits & 0xFFFFFFFFFFFFL);
  }

  /**
   * Returns the 60-bit timestamp value of the UUID in a long. 
   * This field only exists in a time-based (version 1) UUID.
   *
   * @throws UnsupportedOperationException if the UUID type is not 1.
   * @returns a long with the timestamp value.
   */
  public long timestamp()
  {
    if( version() != 1 )
      throw new UnsupportedOperationException("Not a type 1 UUID");
    long time = (( mostSigBits & 0xFFFFFFFF00000000L) >> 32);
    time |= (( mostSigBits & 0xFFFF0000L ) << 16);
    long time_hi = ( mostSigBits & 0xFFFL );
    time |= (time_hi << 48);
    return time;
  }

  /**
   * Generate a Leach-Salz (Variant 2) randomly generated (version 4)
   * UUID.
   *
   */
  public static UUID randomUUID()
  {  
    long lsb = r.nextLong(); 
    long msb = r.nextLong();

    lsb &= 0x3FFFFFFFFFFFFFFFL; 
    lsb |= 0x8000000000000000L; // set top two bits to variant 2

    msb &= 0xFFFFFFFFFFFF0FFFL; 
    msb |= 0x4000; // Version 4; 

    return new UUID( msb, lsb );
  }

  /**
   * Returns a hex String from l, padded to n spaces.
   */
  private String padHex( long l, int n )
  {
    String s = Long.toHexString( l );
    while( s.length() < n )
      s = "0" + s;
    return s;
  }

  /**
   * Returns the variant of the UUID
   *
   * This may be:
   * 0 = Reserved for NCS backwards-compatibility
   * 2 = Leach-Salz (supports the other methods in this class)
   * 6 = Reserved for Microsoft backwards-compatibility
   * 7 = (reserved for future use)
   */
  public int variant()
  {
    // Get the top 3 bits (not all may be part of the variant)
    int v = (int)((leastSigBits & 0xE000000000000000L) >> 61);
    if( (v & 0x04) == 0 ) // msb of the variant is 0
      return 0;
    if( (v & 0x02) == 0 ) // variant is 0 1 (Leach-Salz)
      return 2;
    return v; // 6 or 7 
  }

  /**
   * Returns the version # of the UUID.
   *
   * Valid version numbers for a variant 2 UUID are:
   * 1 = Time based UUID
   * 2 = DCE security UUID
   * 3 = Name-based UUID using MD5 hashing
   * 4 = Randomly generated UUID
   * 5 = Name-based UUID using SHA-1 hashing
   *
   * @return the version number
   */
  public int version()
  {
    return (int)((mostSigBits & 0xF000L) >> 12);
  }
}