1 /*
2 * The contents of this file are subject to the BT "ZEUS" Open Source
3 * Licence (L77741), Version 1.0 (the "Licence"); you may not use this file
4 * except in compliance with the Licence. You may obtain a copy of the Licence
5 * from $ZEUS_INSTALL/licence.html or alternatively from
6 * http://www.labs.bt.com/projects/agents/zeus/licence.htm
7 *
8 * Except as stated in Clause 7 of the Licence, software distributed under the
9 * Licence is distributed WITHOUT WARRANTY OF ANY KIND, either express or
10 * implied. See the Licence for the specific language governing rights and
11 * limitations under the Licence.
12 *
13 * The Original Code is within the package zeus.*.
14 * The Initial Developer of the Original Code is British Telecommunications
15 * public limited company, whose registered office is at 81 Newgate Street,
16 * London, EC1A 7AJ, England. Portions created by British Telecommunications
17 * public limited company are Copyright 1996-9. All Rights Reserved.
18 *
19 * THIS NOTICE MUST BE INCLUDED ON ANY COPY OF THIS FILE
20 */
21
22
23
24 package zeus.concepts.fn;
25
26 import java.util.*;
27 import zeus.util.*;
28 import zeus.concepts.*;
29
30 public class VarFn extends ValueFunction {
31 public String arg = null;
32
33 public VarFn(String arg) {
34 super(LVAR,1);
35 this.arg = arg;
36 }
37
38
39 public ValueFunction mirror() {
40 return new VarFn(arg);
41 }
42
43
44 public String toString() {
45 return arg;
46 }
47
48
49 Object getArg(int position) {
50 if (position != 0) throw new ArrayIndexOutOfBoundsException(position);
51 return arg;
52 }
53
54
55 public ValueFunction duplicate(DuplicationTable table) {
56 String base = arg.substring(1);
57 base = table.getRef(base);
58 String result = "" + arg.charAt(0) + base;
59 return new VarFn(result);
60 }
61
62
63 public boolean references(ValueFunction var) {
64 return equals(var);
65 }
66
67
68 public Vector variables() {
69 Vector out = new Vector();
70 out.addElement(this);
71 return out;
72 }
73
74
75 public boolean isDeterminate() {
76 return false;
77 }
78
79
80 public boolean equals(Object any) {
81 if ( !(any instanceof VarFn) ) return false;
82 VarFn fn = (VarFn)any;
83 return arg.equals((String)fn.getArg());
84 }
85
86
87 ValueFunction unify(ValueFunction fn, Bindings b) {
88 return fn;
89 }
90
91 }