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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  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 multiplication<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: ASTMulNode.java 463298 2006-10-12 16:10:32Z henning $
39   */
40  public class ASTMulNode extends SimpleNode
41  {
42      /**
43       * @param id
44       */
45      public ASTMulNode(int id)
46      {
47          super(id);
48      }
49  
50      /**
51       * @param p
52       * @param id
53       */
54      public ASTMulNode(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 product of the two args.
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 multiplication 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 
115         if ( !( left instanceof Number )  || !( right instanceof Number ))
116         {
117             log.error((!(left instanceof Number) ? "Left" : "Right")
118                            + " side of multiplication operation is not a Number. "
119                            +  context.getCurrentTemplateName() + " [line " + getLine()
120                            + ", column " + getColumn() + "]");
121 
122             return null;
123         }
124 
125         return MathUtils.multiply( (Number)left, (Number)right);
126     }
127 }
128 
129 
130 
131