01: /*
02: * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
03: *
04: * This file is part of Resin(R) Open Source
05: *
06: * Each copy or derived work must preserve the copyright notice and this
07: * notice unmodified.
08: *
09: * 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: * Binds the expression as a select item.
47: */
48: public AmberExpr bindSelect(QueryParser parser) {
49: return this ;
50: }
51:
52: /**
53: * Generates the literal.
54: */
55: public void generateWhere(CharBuffer cb) {
56: cb.append("NULL");
57: }
58:
59: /**
60: * Generates the (update) literal.
61: */
62: public void generateUpdateWhere(CharBuffer cb) {
63: generateWhere(cb);
64: }
65:
66: /**
67: * Generates the having expression.
68: */
69: public void generateHaving(CharBuffer cb) {
70: generateWhere(cb);
71: }
72:
73: public String toString() {
74: return "NULL";
75: }
76: }
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