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


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
20 /**
21  * Please look at the Parser.jjt file which is
22  * what controls the generation of this class.
23  *
24  * @author <a HREF="mailto:jvanzyl@apache.org">Jason van Zyl</a>
25  * @author <a HREF="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
26  * @version $Id: ASTIfStatement.java,v 1.9.8.1 2004/03/03 23:22:58 geirm Exp $
27 */
28
29
30 import java.io.Writer JavaDoc;
31 import java.io.IOException JavaDoc;
32
33 import org.apache.velocity.context.InternalContextAdapter;
34 import org.apache.velocity.runtime.parser.*;
35
36 import org.apache.velocity.exception.MethodInvocationException;
37 import org.apache.velocity.exception.ParseErrorException;
38 import org.apache.velocity.exception.ResourceNotFoundException;
39
40
41 public class ASTIfStatement extends SimpleNode
42 {
43     public ASTIfStatement(int id)
44     {
45         super(id);
46     }
47     
48     public ASTIfStatement(Parser p, int id)
49     {
50         super(p, id);
51     }
52     
53     /** Accept the visitor. **/
54     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data)
55     {
56         return visitor.visit(this, data);
57     }
58     
59     public boolean render( InternalContextAdapter context, Writer JavaDoc writer)
60         throws IOException JavaDoc,MethodInvocationException,
61             ResourceNotFoundException, ParseErrorException
62     {
63         /*
64          * Check if the #if(expression) construct evaluates to true:
65          * if so render and leave immediately because there
66          * is nothing left to do!
67          */
68         if (jjtGetChild(0).evaluate(context))
69         {
70             jjtGetChild(1).render(context, writer);
71             return true;
72         }
73     
74         int totalNodes = jjtGetNumChildren();
75         
76         /*
77          * Now check the remaining nodes left in the
78          * if construct. The nodes are either elseif
79          * nodes or else nodes. Each of these node
80          * types knows how to evaluate themselves. If
81          * a node evaluates to true then the node will
82          * render itself and this method will return
83          * as there is nothing left to do.
84          */
85         for (int i = 2; i < totalNodes; i++)
86         {
87             if (jjtGetChild(i).evaluate(context))
88             {
89                 jjtGetChild(i).render(context, writer);
90                 return true;
91             }
92         }
93     
94         /*
95          * This is reached when an ASTIfStatement
96          * consists of an if/elseif sequence where
97          * none of the nodes evaluate to true.
98          */
99         return true;
100     }
101
102     public void process( InternalContextAdapter context, ParserVisitor visitor)
103     {
104     }
105 }
106
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