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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 FactFn extends ValueFunction {
31     protected Fact arg = null;
32  
33     public FactFn(Fact arg) {
34        super(FACT,7);
35        this.arg = arg;
36     }
37     public String toString() {
38        return arg.toString();
39     }
40     Object getArg(int position) {
41        if (position != 0) throw new ArrayIndexOutOfBoundsException(position);
42        return arg;
43     }
44     public Fact getFact() {
45        return arg;
46     }
47     public boolean references(ValueFunction var) {
48        ValueFunction[] variables = arg.variables();
49        for(int i = 0; i < variables.length; i++ )
50           if ( variables[i].references(var) )
51              return true;
52        return false;
53     }
54     public Vector variables() {
55        Vector List = new Vector();
56        ValueFunction[] variables = arg.variables();
57        for(int i = 0; i < variables.length; i++ )
58           List.addElement(variables[i]);
59        return List;
60     }
61     public boolean isDeterminate() {
62        return arg.isDeterminate();
63     }
64     public ValueFunction resolve(ResolutionContext c, Bindings b) {
65        if ( arg.resolve(c,b) ) return this;
66        return null;
67     }
68     public ValueFunction duplicate(DuplicationTable table) {
69        Fact f1 = arg.duplicate(table);
70        return new FactFn(f1);
71     }
72     public ValueFunction mirror() {
73        return new FactFn(new Fact(arg));
74     }
75     public boolean equals(Object any) {
76        if ( !(any instanceof FactFn) ) return false;
77        FactFn fn = (FactFn)any;
78        return arg.equals(fn.getArg());
79     }
80     ValueFunction unify(ValueFunction fn, Bindings b) {
81        switch(fn.getID()) {
82           case FACT:
83                Fact f1 = (Fact)fn.getArg(0);
84                if ( arg.unifiesWith(f1,b) ) {
85                   arg.resolve(b);
86                   return this;
87                }
88                return null;
89  
90           default:
91                return null;
92        }
93     }
94     public int baseID() {
95        return getID();
96     }
97  
98  }