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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 BoolFn extends LogicalFn implements PrimitiveFn {
31     protected boolean arg;
32     public static final BoolFn trueFn = new BoolFn("true");
33     public static final BoolFn falseFn = new BoolFn("false");
34  
35     public static final BoolFn newBoolFn(boolean arg) {
36        return ( arg ) ? trueFn : falseFn;
37     }
38     public static final BoolFn newBoolFn(String arg) {
39        if ( arg.equals("true") ) return trueFn;
40        else if ( arg.equals("false") ) return falseFn;
41        else 
42           throw new IllegalArgumentException("Unknown operand \'" + arg +
43              "\' in boolean function");
44     }
45  
46     public ValueFunction mirror() {
47        return new BoolFn(toString());
48     }
49     
50     private BoolFn(String arg) {
51        super(BOOL,10);
52        this.arg = (Boolean.valueOf(arg)).booleanValue();
53     }
54     public String toString() {
55        return (new Boolean(arg)).toString();
56     }
57     Object getArg(int position) {
58        if ( position != 0 )
59           throw new ArrayIndexOutOfBoundsException(position);
60        return new Boolean(arg);
61     }
62     public boolean getValue() {
63        return arg;
64     }
65     public boolean isDeterminate() {
66        return true;
67     }
68     public int evaluate() {
69        return  arg ? TRUE : FALSE;
70     }      
71     public boolean equals(Object any) {
72        if ( !(any instanceof BoolFn) ) return false;
73        BoolFn fn = (BoolFn)any;
74        return arg == fn.getValue();
75     }
76     public boolean less(Object fn) {
77        return false;
78     }
79     public boolean references(ValueFunction var) {
80        return false;
81     }
82  }