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.FromItem;
32: import com.caucho.amber.query.QueryParser;
33: import com.caucho.amber.query.SelectQuery;
34: import com.caucho.util.CharBuffer;
35:
36: /**
37: * Represents an exists query expression
38: */
39: public class ExistsExpr extends AbstractAmberExpr {
40: private SelectQuery _query;
41:
42: public ExistsExpr(SelectQuery query) {
43: _query = query;
44: }
45:
46: /**
47: * Binds the expression as a select item.
48: */
49: public AmberExpr bindSelect(QueryParser parser) {
50: return this ;
51: }
52:
53: /**
54: * Returns true for a boolean expression.
55: */
56: public boolean isBoolean() {
57: return true;
58: }
59:
60: /**
61: * Returns true if the expression uses the from item.
62: */
63: public boolean usesFrom(FromItem from, int type, boolean isNot) {
64: return _query.usesFrom(from, type);
65: }
66:
67: /**
68: * Generates the where expression.
69: */
70: public void generateWhere(CharBuffer cb) {
71: cb.append("EXISTS(");
72: cb.append(_query.generateLoadSQL(false));
73: cb.append(')');
74: }
75:
76: /**
77: * Generates the (update) where expression.
78: */
79: public void generateUpdateWhere(CharBuffer cb) {
80: generateWhere(cb);
81: }
82:
83: /**
84: * Generates the having expression.
85: */
86: public void generateHaving(CharBuffer cb) {
87: generateWhere(cb);
88: }
89: }
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