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.rete;
25
26 import java.util.*;
27 import zeus.util.*;
28 import zeus.concepts.*;
29 import zeus.concepts.fn.*;
30
31
32 class AttributeNode extends PatternNode {
33 ValueFunction value = null;
34 String attribute = null;
35
36 AttributeNode(ReteEngine engine, String attribute, ValueFunction value) {
37 super(engine);
38 this.attribute = attribute;
39 this.value = value;
40 }
41 void evaluate(String path, int tag, int type, Vector input, Bindings b) {
42 // System.out.println("evaluating attribute node" + toString());
43 Assert.notFalse(type == SINGLE);
44 Assert.notFalse(input.size() == 1);
45 Fact f = (Fact)input.elementAt(0);
46 ValueFunction v = f.getFn(attribute);
47 if ( v != null && value.unifiesWith(v,b) != null )
48 propagate(path,tag,input,b);
49 }
50 public boolean equals(Object any) {
51 if ( any instanceof AttributeNode ) {
52 AttributeNode node = (AttributeNode)any;
53 return attribute.equals(node.attribute) && value.equals(node.value);
54 }
55 return false;
56 }
57 public String toString() {
58 return "AttributeNode(" + attribute + "," + value + ")";
59 }
60 }