Classes used by the Java backend, particularly in the implementation

Estimated hours taken: 10.

Classes used by the Java backend, particularly in the implementation
of RTTI.

java/Compare.java:
java/Unify.java:
 	New files.  Java classes for implementation of wrapper classes
	around the builtin `unify'and `compare' predicates.

java/JavaInternal.java:
 	New file.  Java class for storing runtime information such
	as command line arguments.

java/DuExistInfo.java:
java/DuExistLocn.java:
java/DuFunctorDesc.java:
java/DuPtagLayout.java:
java/EnumFunctorDesc.java:
java/NotagFunctorDesc.java:
java/ProcAddr.java:
java/PseudoTypeInfo.java:
java/Sectag_Locn.java:
java/TypeCtorInfo_Struct.java
java/TypeCtorRep.java:
java/TypeFunctors.java:
java/TypeLayout.java:
 	New files.  Java classes for implementing Mercury RTTI.

java/UnreachableDefault.java:
 	New file.  Runtime exception that signals that unreachable
	default case in a switch statement has been reached.

runtime/mercury_type_info.h:
	Update comments to mention that Java runtime classes will
	need to be altered if structures in this file are.

java/TypeFunctors.java

@@ -0,0 +1,21 @@
+//
+// Copyright (C) 2001 The University of Melbourne.
+// This file may only be copied under the terms of the GNU Library General
+// Public License - see the file COPYING.LIB in the Mercury distribution.
+//
+
+package mercury.runtime;
+
+//   XXX In the C backend this was a union.  
+//   It would (eventually) be better to have derived classes
+//   for each of the unions constructors and make them all extend
+//   this class (rather like we do with the generated code from the 
+//   mercury compiler.  That way we can just use the `instanceof' operator
+//   to work out what each instance is.
+
+public class TypeFunctors {
+	public java.lang.Object functors_init;
+	public mercury.runtime.DuFunctorDesc[] functors_du;
+	public mercury.runtime.EnumFunctorDesc[] functors_enum;
+	public mercury.runtime.NotagFunctorDesc functors_notag;
+}