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


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 public class ASTNENode extends SimpleNode
25 {
26     public ASTNENode(int id)
27     {
28         super(id);
29     }
30
31     public ASTNENode(Parser p, int id)
32     {
33         super(p, id);
34     }
35
36     /** Accept the visitor. **/
37     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data)
38     {
39         return visitor.visit(this, data);
40     }
41
42     public boolean evaluate( InternalContextAdapter context)
43         throws MethodInvocationException
44     {
45         Object JavaDoc left = jjtGetChild(0).value( context );
46         Object JavaDoc right = jjtGetChild(1).value( context );
47
48         /*
49          * null check
50          */
51
52         if ( left == null || right == null)
53         {
54             rsvc.error( ( left == null ? "Left" : "Right" ) + " side ("
55                            + jjtGetChild( (left == null? 0 : 1) ).literal()
56                            + ") of '!=' operation has null value."
57                            + " Operation not possible. "
58                            + context.getCurrentTemplateName() + " [line " + getLine()
59                            + ", column " + getColumn() + "]");
60             return false;
61
62         }
63
64
65         /*
66          * check to see if they are the same class. I don't think this is slower
67          * as I don't think that getClass() results in object creation, and we can
68          * extend == to handle all classes
69          */
70
71         if (left.getClass().equals( right.getClass() ) )
72         {
73             return !(left.equals( right ));
74         }
75         else
76         {
77             rsvc.error("Error in evaluation of != expression."
78                           + " Both arguments must be of the same Class."
79                           + " Currently left = " + left.getClass() + ", right = "
80                           + right.getClass() + ". "
81                           + context.getCurrentTemplateName() + " [line " + getLine()
82                           + ", column " + getColumn() + "] (ASTEQNode)");
83             
84             return false;
85         }
86     }
87
88     public Object JavaDoc value(InternalContextAdapter context)
89         throws MethodInvocationException
90     {
91         boolean val = evaluate(context);
92
93         return val ? Boolean.TRUE : Boolean.FALSE;
94     }
95
96 }
97
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