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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  /**
23   * Handles modulus division<br><br>
24   *
25   * Please look at the Parser.jjt file which is
26   * what controls the generation of this class.
27   *
28   * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
29   * @author <a href="mailto:pero@antaramusic.de">Peter Romianowski</a>
30   * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
31   * @version $Id: ASTModNode.java 517553 2007-03-13 06:09:58Z wglass $
32   */
33  import org.apache.velocity.context.InternalContextAdapter;
34  import org.apache.velocity.exception.MethodInvocationException;
35  import org.apache.velocity.runtime.parser.Parser;
36  import org.apache.velocity.util.TemplateNumber;
37  
38  /**
39   *
40   */
41  public class ASTModNode extends SimpleNode
42  {
43      /**
44       * @param id
45       */
46      public ASTModNode(int id)
47      {
48          super(id);
49      }
50  
51      /**
52       * @param p
53       * @param id
54       */
55      public ASTModNode(Parser p, int id)
56      {
57          super(p, id);
58      }
59  
60      /**
61       * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.node.ParserVisitor, java.lang.Object)
62       */
63      public Object jjtAccept(ParserVisitor visitor, Object data)
64      {
65          return visitor.visit(this, data);
66      }
67  
68      /**
69       * @see org.apache.velocity.runtime.parser.node.SimpleNode#value(org.apache.velocity.context.InternalContextAdapter)
70       */
71      public Object value( InternalContextAdapter context)
72          throws MethodInvocationException
73      {
74          /*
75           *  get the two args
76           */
77  
78          Object left = jjtGetChild(0).value( context );
79          Object right = jjtGetChild(1).value( context );
80  
81          /*
82           *  if either is null, lets log and bail
83           */
84  
85          if (left == null || right == null)
86          {
87              log.error((left == null ? "Left" : "Right")
88                             + " side ("
89                             + jjtGetChild( (left == null? 0 : 1) ).literal()
90                             + ") of modulus operation has null value."
91                             + " Operation not possible. "
92                             + context.getCurrentTemplateName() + " [line " + getLine()
93                             + ", column " + getColumn() + "]");
94              return null;
95          }
96  
97          /*
98           *  convert to Number if applicable
99           */
100         if (left instanceof TemplateNumber)
101         {
102            left = ( (TemplateNumber) left).getAsNumber();
103         }
104         if (right instanceof TemplateNumber)
105         {
106            right = ( (TemplateNumber) right).getAsNumber();
107         }
108 
109         /*
110          * Both values must be a number.
111          */
112         if ( ! (left instanceof Number) || ! (right instanceof Number) )
113         {
114 
115             log.error((!(left instanceof Number) ? "Left" : "Right")
116                            + " side "
117                            + " of modulus operation is not a Number. "
118                            + context.getCurrentTemplateName() + " [line " + getLine()
119                            + ", column " + getColumn() + "]");
120             return null;
121 
122         }
123 
124         /*
125          *  check for divide / modulo by 0
126          */
127         if ( MathUtils.isZero ( (Number) right ) )
128         {
129 
130             log.error("Right side of modulus operation is zero. Must be non-zero. "
131                            + context.getCurrentTemplateName() + " [line " + getLine()
132                            + ", column " + getColumn() + "]");
133             return null;
134 
135         }
136 
137         return MathUtils.modulo ((Number)left, (Number)right);
138 
139     }
140 }
141