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.MathException;
24 import org.apache.velocity.exception.MethodInvocationException;
25 import org.apache.velocity.exception.TemplateInitException;
26 import org.apache.velocity.runtime.RuntimeConstants;
27 import org.apache.velocity.runtime.parser.Parser;
28 import org.apache.velocity.util.TemplateNumber;
29
30 /**
31 * Helps handle math<br><br>
32 *
33 * Please look at the Parser.jjt file which is
34 * what controls the generation of this class.
35 *
36 * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
37 * @author <a href="mailto:pero@antaramusic.de">Peter Romianowski</a>
38 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
39 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
40 * @author Nathan Bubna
41 * @version $Id: ASTMathNode.java 517553 2007-03-13 06:09:58Z wglass $
42 */
43 public abstract class ASTMathNode extends SimpleNode
44 {
45 protected boolean strictMode = false;
46
47 public ASTMathNode(int id)
48 {
49 super(id);
50 }
51
52 public ASTMathNode(Parser p, int id)
53 {
54 super(p, id);
55 }
56
57 /**
58 * {@inheritDoc}
59 */
60 public Object init(InternalContextAdapter context, Object data) throws TemplateInitException
61 {
62 super.init(context, data);
63 strictMode = rsvc.getBoolean(RuntimeConstants.STRICT_MATH, false);
64 return data;
65 }
66
67 /**
68 * {@inheritDoc}
69 */
70 public Object jjtAccept(ParserVisitor visitor, Object data)
71 {
72 return visitor.visit(this, data);
73 }
74
75 /**
76 * gets the two args and performs the operation on them
77 *
78 * @param context
79 * @return result or null
80 * @throws MethodInvocationException
81 */
82 public Object value(InternalContextAdapter context) throws MethodInvocationException
83 {
84 Object left = jjtGetChild(0).value(context);
85 Object right = jjtGetChild(1).value(context);
86
87 /*
88 * should we do anything special here?
89 */
90 Object special = handleSpecial(left, right, context);
91 if (special != null)
92 {
93 return special;
94 }
95
96 /*
97 * convert to Number if applicable
98 */
99 if (left instanceof TemplateNumber)
100 {
101 left = ((TemplateNumber)left).getAsNumber();
102 }
103 if (right instanceof TemplateNumber)
104 {
105 right = ((TemplateNumber)right).getAsNumber();
106 }
107
108 /*
109 * if not a Number, not much we can do
110 */
111 if (!(left instanceof Number) || !(right instanceof Number))
112 {
113 boolean wrongright = (left instanceof Number);
114 boolean wrongtype = wrongright ? right != null : left != null;
115 String msg = (wrongright ? "Right" : "Left")
116 + " side of math operation ("
117 + jjtGetChild(wrongright ? 1 : 0).literal() + ") "
118 + (wrongtype ? "is not a Number. " : "has a null value. ")
119 + getLocation(context);
120 if (strictMode)
121 {
122 log.error(msg);
123 throw new MathException(msg);
124 }
125 else
126 {
127 log.debug(msg);
128 return null;
129 }
130 }
131
132 return perform((Number)left, (Number)right, context);
133 }
134
135 /**
136 * Extension hook to allow special behavior by subclasses
137 * If this method returns a non-null value, that is returned,
138 * rather than the result of the math operation.
139 * @see ASTAddNode#handleSpecial
140 */
141 protected Object handleSpecial(Object left, Object right, InternalContextAdapter context)
142 {
143 // do nothing, this is an extension hook
144 return null;
145 }
146
147 /**
148 * Performs the math operation represented by this node.
149 */
150 public abstract Number perform(Number left, Number right, InternalContextAdapter context);
151
152 }
153
154
155
156