An implementation of Universal Unique Identifier (UUID). See http://tools.ietf.org/html/rfc4122

The current implementation supports only a JVM backend due to dependencies upon [[java.security::MessageDigest]], to produce random bytes, and to implement MD5/SHA-1 hashing, respectively.

According to the standard, the following components make up a UUID :

• timeLow (8 digits)
• timeMid (4 digits)
• timeHiVersion (4 digits)
• clockSeqHiVariant (2 digits)
• clockSeqLow (2 digits)
• node (12 digits)

For example, for the following UUID: 5561de0e-64ad-4d9b-94f2-46926fc44121:

• timeLow = 5561de0e
• timeMid = 64ad
• timeHiVersion = 4d9b
• clockSeqHiVariant = 94
• clockSeqLow = f2
• node = 46926fc44121

Since the above UUID was generated randomly, its version is 4, and is the first digit of the timeHiVersion.

The variant is 2. Despite any variant with a leading bit of 1 being supported, with all variants supported for either backward or future compatibility, only variant 2 is in actual use.

Currently, only versions 3 (MD5 sum), 4 (randomly generated), and 5 (SHA1) are supported.

Usage:

To obtain a UUID from a UUID String:

   UUID? uuidFromString = fromString("01c17b28-380d-48e2-9d6d-5c9f92b3546d");

To generate a UUID version 3 as an MD5 hash of a String with

   UUID uuidVersion3 = uuid3Md5("some string");

To generate a UUID version 5 as an SHA1 hash of a String and namespace with

   UUID uuidVersion5 = uuid5Sha1("some string", fromString("08110431-c913-4e72-b3e6-d3baad15f4db"));

To generate a random UUID version 4:

   UUID uuidVersion4 = uuid4Random();

In addition support functions to convert from/to Java [[java.util::UUID]]s.

To obtain a Java [[java.util::UUID]] from a UUID:

   import java.util {
      JUUID=UUID
   }

   JUUID javaUuid = toJavaUuid(ceylonUuid);

To obtain a UUID from a Java [[java.util::UUID]]:

   UUID javaUuid = toUuid(javaUuid);

Also, there is a WrappedUUID class that subclasses the herd.chayote [[herd.chayote.wrapper_type::WrapperType]].

   class AccountId(UUID baseValue) extends WrappedUUID(baseValue) {}
   class ReferenceId(UUID baseValue) extends WrappedUUID(baseValue) {}

   value accountId1 = AccountId(fromString());
   value accountId2 = AccountId(fromString());

   value refId1 = ReferenceId(fromString());
   value refId2 = ReferenceId(fromString());

   assertFalse(accountId1.equals(accountId2);
   assertFalse(accountId1.equals(referenceId1);
   assertFalse(referenceId2.equals(accountId2);