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


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.runtime.parser.Parser;
20 import org.apache.velocity.context.InternalContextAdapter;
21
22 import org.apache.velocity.exception.MethodInvocationException;
23
24 /**
25  * Please look at the Parser.jjt file which is
26  * what controls the generation of this class.
27  *
28  * @author <a HREF="mailto:jvanzyl@apache.org">Jason van Zyl</a>
29  * @author <a HREF="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
30  * @version $Id: ASTOrNode.java,v 1.6.8.1 2004/03/03 23:22:59 geirm Exp $
31 */
32 public class ASTOrNode extends SimpleNode
33 {
34     public ASTOrNode(int id)
35     {
36         super(id);
37     }
38
39     public ASTOrNode(Parser p, int id)
40     {
41         super(p, id);
42     }
43
44     /** Accept the visitor. **/
45     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data)
46     {
47         return visitor.visit(this, data);
48     }
49
50     /**
51      * Returns the value of the expression.
52      * Since the value of the expression is simply the boolean
53      * result of evaluate(), lets return that.
54      */
55     public Object JavaDoc value(InternalContextAdapter context )
56         throws MethodInvocationException
57     {
58         return new Boolean JavaDoc( evaluate( context ) );
59     }
60
61     /**
62      * the logical or :
63      * the rule :
64      * left || null -> left
65      * null || right -> right
66      * null || null -> false
67      * left || right -> left || right
68      */
69     public boolean evaluate( InternalContextAdapter context)
70         throws MethodInvocationException
71     {
72         Node left = jjtGetChild(0);
73         Node right = jjtGetChild(1);
74
75         /*
76          * if the left is not null and true, then true
77          */
78         
79         if (left != null && left.evaluate( context ) )
80             return true;
81
82         /*
83          * same for right
84          */
85
86         if ( right != null && right.evaluate( context ) )
87             return true;
88
89         return false;
90     }
91 }
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