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Java > Open Source Codes > com > hp > hpl > jena > reasoner > rulesys > builtins > Product


1 /******************************************************************
2  * File: Product.java
3  * Created by: Dave Reynolds
4  * Created on: 24-Aug-2003
5  *
6  * (c) Copyright 2003, 2004, 2005 Hewlett-Packard Development Company, LP
7  * [See end of file]
8  * $Id: Product.java,v 1.5 2005/02/21 12:17:33 andy_seaborne Exp $
9  *****************************************************************/
10 package com.hp.hpl.jena.reasoner.rulesys.builtins;
11
12 import com.hp.hpl.jena.reasoner.rulesys.*;
13 import com.hp.hpl.jena.graph.*;
14
15 /**
16  * Bind the third arg to the product of the first two args.
17  *
18  * @author <a HREF="mailto:der@hplb.hpl.hp.com">Dave Reynolds</a>
19  * @version $Revision: 1.5 $ on $Date: 2005/02/21 12:17:33 $
20  */
21 public class Product extends BaseBuiltin {
22
23     /**
24      * Return a name for this builtin, normally this will be the name of the
25      * functor that will be used to invoke it.
26      */
27     public String JavaDoc getName() {
28         return "product";
29     }
30     
31     /**
32      * Return the expected number of arguments for this functor or 0 if the number is flexible.
33      */
34     public int getArgLength() {
35         return 3;
36     }
37
38     /**
39      * This method is invoked when the builtin is called in a rule body.
40      * @param args the array of argument values for the builtin, this is an array
41      * of Nodes, some of which may be Node_RuleVariables.
42      * @param length the length of the argument list, may be less than the length of the args array
43      * for some rule engines
44      * @param context an execution context giving access to other relevant data
45      * @return return true if the buildin predicate is deemed to have succeeded in
46      * the current environment
47      */
48     public boolean bodyCall(Node[] args, int length, RuleContext context) {
49         checkArgs(length, context);
50         BindingEnvironment env = context.getEnv();
51         Node n1 = getArg(0, args, context);
52         Node n2 = getArg(1, args, context);
53         if (n1.isLiteral() && n2.isLiteral()) {
54             Object JavaDoc v1 = n1.getLiteral().getValue();
55             Object JavaDoc v2 = n2.getLiteral().getValue();
56             Node sum = null;
57             if (v1 instanceof Number JavaDoc && v2 instanceof Number JavaDoc) {
58                 Number JavaDoc nv1 = (Number JavaDoc)v1;
59                 Number JavaDoc nv2 = (Number JavaDoc)v2;
60                 if (v1 instanceof Float JavaDoc || v1 instanceof Double JavaDoc
61                 || v2 instanceof Float JavaDoc || v2 instanceof Double JavaDoc) {
62                     sum = Util.makeDoubleNode(nv1.doubleValue() * nv2.doubleValue());
63                 } else {
64                     sum = Util.makeLongNode(nv1.longValue() * nv2.longValue());
65                 }
66                 env.bind(args[2], sum);
67                 return true;
68             }
69         }
70         // Doesn't (yet) handle partially bound cases
71 return false;
72     }
73     
74 }
75
76
77
78 /*
79     (c) Copyright 2003, 2004, 2005 Hewlett-Packard Development Company, LP
80     All rights reserved.
81
82     Redistribution and use in source and binary forms, with or without
83     modification, are permitted provided that the following conditions
84     are met:
85
86     1. Redistributions of source code must retain the above copyright
87        notice, this list of conditions and the following disclaimer.
88
89     2. Redistributions in binary form must reproduce the above copyright
90        notice, this list of conditions and the following disclaimer in the
91        documentation and/or other materials provided with the distribution.
92
93     3. The name of the author may not be used to endorse or promote products
94        derived from this software without specific prior written permission.
95
96     THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
97     IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
98     OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
99     IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
100     INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
101     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
102     DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
103     THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
104     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
105     THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
106 */
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