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Java > Open Source Codes > gov > nasa > jpf > jvm > Ref


1 //
2 // Copyright (C) 2005 United States Government as represented by the
3 // Administrator of the National Aeronautics and Space Administration
4 // (NASA). All Rights Reserved.
5 //
6 // This software is distributed under the NASA Open Source Agreement
7 // (NOSA), version 1.3. The NOSA has been approved by the Open Source
8 // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
9 // directory tree for the complete NOSA document.
10 //
11 // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12 // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13 // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14 // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15 // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16 // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17 // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18 //
19 package gov.nasa.jpf.jvm;
20
21 /**
22  * helper class to store reference objects
23  * <2do> check how 'isClass' correlates with ClassRef
24  */
25 public abstract class Ref {
26   public static final ObjRef NULL = new ObjRef(-1);
27   int reference;
28   boolean isClass;
29
30   protected Ref (int r, boolean c) {
31     reference = r;
32     isClass = c;
33   }
34
35   public boolean isClass () {
36     return isClass;
37   }
38
39   public boolean isNull () {
40     return reference == -1;
41   }
42
43   public int getReference () {
44     return reference;
45   }
46
47   public abstract Object JavaDoc clone ();
48
49   public boolean equals (Object JavaDoc o) {
50     return (reference == ((Ref) o).reference) &&
51            (isClass == ((Ref) o).isClass);
52   }
53
54   public int hashCode () {
55     return reference;
56   }
57
58   public String JavaDoc toString () {
59     return (isClass ? "@" : "#") + reference;
60   }
61 }
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