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Java > Open Source Codes > org > apache > velocity > runtime > parser > node > ASTMulNode


1 package org.apache.velocity.runtime.parser.node;
2
3 /*
4  * Copyright 2000-2001,2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import org.apache.velocity.context.InternalContextAdapter;
20 import org.apache.velocity.runtime.parser.Parser;
21
22 import org.apache.velocity.exception.MethodInvocationException;
23
24 /**
25  * Handles integer multiplication
26  *
27  * Please look at the Parser.jjt file which is
28  * what controls the generation of this class.
29  *
30  * @author <a HREF="mailto:jvanzyl@apache.org">Jason van Zyl</a>
31  * @author <a HREF="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
32  * @version $Id: ASTMulNode.java,v 1.7.8.1 2004/03/03 23:22:59 geirm Exp $
33 */
34 public class ASTMulNode extends SimpleNode
35 {
36     public ASTMulNode(int id)
37     {
38         super(id);
39     }
40
41     public ASTMulNode(Parser p, int id)
42     {
43         super(p, id);
44     }
45
46     /** Accept the visitor. **/
47     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data)
48     {
49         return visitor.visit(this, data);
50     }
51
52     /**
53      * computes the product of the two args. Returns null if either arg is null
54      * or if either arg is not an integer
55      */
56     public Object JavaDoc value( InternalContextAdapter context )
57         throws MethodInvocationException
58     {
59         /*
60          * get the two args
61          */
62
63         Object JavaDoc left = jjtGetChild(0).value( context );
64         Object JavaDoc right = jjtGetChild(1).value( context );
65
66         /*
67          * if either is null, lets log and bail
68          */
69
70         if (left == null || right == null)
71         {
72             rsvc.error( ( left == null ? "Left" : "Right" ) + " side ("
73                            + jjtGetChild( (left == null? 0 : 1) ).literal()
74                            + ") of multiplication operation has null value."
75                            + " Operation not possible. "
76                            + context.getCurrentTemplateName() + " [line " + getLine()
77                            + ", column " + getColumn() + "]");
78             return null;
79         }
80         
81         /*
82          * if not an Integer, not much we can do either
83          */
84
85         if ( !( left instanceof Integer JavaDoc ) || !( right instanceof Integer JavaDoc ))
86         {
87             rsvc.error( ( !( left instanceof Integer JavaDoc ) ? "Left" : "Right" )
88                            + " side of multiplication operation is not a valid type. "
89                            + "Currently only integers (1,2,3...) and Integer type is supported. "
90                            + context.getCurrentTemplateName() + " [line " + getLine()
91                            + ", column " + getColumn() + "]");
92  
93             return null;
94         }
95
96         return new Integer JavaDoc( ( (Integer JavaDoc) left ).intValue() * ( (Integer JavaDoc) right ).intValue() );
97     }
98 }
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