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Java > Open Source Codes > com > caucho > amber > expr > NullExpr


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free Software Foundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.amber.expr;
30
31 import com.caucho.amber.query.QueryParser;
32 import com.caucho.util.CharBuffer;
33
34 /**
35  * Null expression for Amber.
36  */
37 public class NullExpr extends AbstractAmberExpr {
38
39   /**
40    * Creates a new null expression.
41    */
42   public NullExpr()
43   {
44   }
45
46   /**
47    * Binds the expression as a select item.
48    */
49   public AmberExpr bindSelect(QueryParser parser)
50   {
51     return this;
52   }
53
54   /**
55    * Generates the literal.
56    */
57   public void generateWhere(CharBuffer cb)
58   {
59     cb.append("NULL");
60   }
61
62   /**
63    * Generates the (update) literal.
64    */
65   public void generateUpdateWhere(CharBuffer cb)
66   {
67     generateWhere(cb);
68   }
69
70   /**
71    * Generates the having expression.
72    */
73   public void generateHaving(CharBuffer cb)
74   {
75     generateWhere(cb);
76   }
77
78   public String JavaDoc toString()
79   {
80     return "NULL";
81   }
82 }
83
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