1 package org.apache.velocity.runtime.parser.node;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import org.apache.velocity.context.InternalContextAdapter;
23 import org.apache.velocity.exception.MethodInvocationException;
24 import org.apache.velocity.runtime.parser.Parser;
25 import org.apache.velocity.util.TemplateNumber;
26
27 /**
28 * Handles subtraction of nodes (in #set() )<br><br>
29 *
30 * Please look at the Parser.jjt file which is
31 * what controls the generation of this class.
32 *
33 * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
34 * @author <a href="mailto:pero@antaramusic.de">Peter Romianowski</a>
35 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
36 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
37 * @version $Id: ASTSubtractNode.java 517553 2007-03-13 06:09:58Z wglass $
38 */
39 public class ASTSubtractNode extends SimpleNode
40 {
41 /**
42 * @param id
43 */
44 public ASTSubtractNode(int id)
45 {
46 super(id);
47 }
48
49 /**
50 * @param p
51 * @param id
52 */
53 public ASTSubtractNode(Parser p, int id)
54 {
55 super(p, id);
56 }
57
58 /**
59 * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.node.ParserVisitor, java.lang.Object)
60 */
61 public Object jjtAccept(ParserVisitor visitor, Object data)
62 {
63 return visitor.visit(this, data);
64 }
65
66 /**
67 * computes the value of the subtraction.
68 * @param context
69 * @return result or null
70 * @throws MethodInvocationException
71 */
72 public Object value( InternalContextAdapter context)
73 throws MethodInvocationException
74 {
75 /*
76 * get the two args
77 */
78
79 Object left = jjtGetChild(0).value( context );
80 Object right = jjtGetChild(1).value( context );
81
82 /*
83 * if either is null, lets log and bail
84 */
85
86 if (left == null || right == null)
87 {
88 log.error((left == null ? "Left" : "Right")
89 + " side ("
90 + jjtGetChild( (left == null? 0 : 1) ).literal()
91 + ") of subtraction operation has null value."
92 + " Operation not possible. "
93 + context.getCurrentTemplateName() + " [line " + getLine()
94 + ", column " + getColumn() + "]");
95 return null;
96 }
97
98 /*
99 * convert to Number if applicable
100 */
101 if (left instanceof TemplateNumber)
102 {
103 left = ( (TemplateNumber) left).getAsNumber();
104 }
105 if (right instanceof TemplateNumber)
106 {
107 right = ( (TemplateNumber) right).getAsNumber();
108 }
109
110 /*
111 * if not a Number, not much we can do either
112 */
113 if ( !( left instanceof Number ) || !( right instanceof Number ))
114 {
115 log.error((!(left instanceof Number) ? "Left" : "Right")
116 + " side of subtraction operation is not a Number. "
117 + context.getCurrentTemplateName() + " [line " + getLine()
118 + ", column " + getColumn() + "]");
119 return null;
120 }
121
122 return MathUtils.subtract ( (Number)left,(Number)right);
123 }
124 }
125
126
127