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.runtime.parser.ParserVisitor;
26 import org.apache.velocity.util.TemplateNumber;
27
28 /**
29 * Handles subtraction of nodes (in #set() )<br><br>
30 *
31 * Please look at the Parser.jjt file which is
32 * what controls the generation of this class.
33 *
34 * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
35 * @author <a href="mailto:pero@antaramusic.de">Peter Romianowski</a>
36 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
37 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
38 * @version $Id: ASTSubtractNode.java 463298 2006-10-12 16:10:32Z henning $
39 */
40 public class ASTSubtractNode extends SimpleNode
41 {
42 /**
43 * @param id
44 */
45 public ASTSubtractNode(int id)
46 {
47 super(id);
48 }
49
50 /**
51 * @param p
52 * @param id
53 */
54 public ASTSubtractNode(Parser p, int id)
55 {
56 super(p, id);
57 }
58
59 /**
60 * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.ParserVisitor, java.lang.Object)
61 */
62 public Object jjtAccept(ParserVisitor visitor, Object data)
63 {
64 return visitor.visit(this, data);
65 }
66
67 /**
68 * computes the value of the subtraction.
69 * @param context
70 * @return result or null
71 * @throws MethodInvocationException
72 */
73 public Object value( InternalContextAdapter context)
74 throws MethodInvocationException
75 {
76 /*
77 * get the two args
78 */
79
80 Object left = jjtGetChild(0).value( context );
81 Object right = jjtGetChild(1).value( context );
82
83 /*
84 * if either is null, lets log and bail
85 */
86
87 if (left == null || right == null)
88 {
89 log.error((left == null ? "Left" : "Right")
90 + " side ("
91 + jjtGetChild( (left == null? 0 : 1) ).literal()
92 + ") of subtraction operation has null value."
93 + " Operation not possible. "
94 + context.getCurrentTemplateName() + " [line " + getLine()
95 + ", column " + getColumn() + "]");
96 return null;
97 }
98
99 /*
100 * convert to Number if applicable
101 */
102 if (left instanceof TemplateNumber)
103 {
104 left = ( (TemplateNumber) left).getAsNumber();
105 }
106 if (right instanceof TemplateNumber)
107 {
108 right = ( (TemplateNumber) right).getAsNumber();
109 }
110
111 /*
112 * if not a Number, not much we can do either
113 */
114 if ( !( left instanceof Number ) || !( right instanceof Number ))
115 {
116 log.error((!(left instanceof Number) ? "Left" : "Right")
117 + " side of subtraction operation is not a Number. "
118 + context.getCurrentTemplateName() + " [line " + getLine()
119 + ", column " + getColumn() + "]");
120 return null;
121 }
122
123 return MathUtils.subtract ( (Number)left,(Number)right);
124 }
125 }
126
127
128