01: /*
02: * $Id: NullConstraint.java,v 1.10 2005/12/20 18:32:46 ahimanikya Exp $
03: * =======================================================================
04: * Copyright (c) 2002-2004 Axion Development Team. All rights reserved.
05: *
06: * Redistribution and use in source and binary forms, with or without
07: * modification, are permitted provided that the following conditions
08: * are met:
09: *
10: * 1. Redistributions of source code must retain the above
11: * copyright notice, this list of conditions and the following
12: * disclaimer.
13: *
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in
16: * the documentation and/or other materials provided with the
17: * distribution.
18: *
19: * 3. The names "Tigris", "Axion", nor the names of its contributors may
20: * not be used to endorse or promote products derived from this
21: * software without specific prior written permission.
22: *
23: * 4. Products derived from this software may not be called "Axion", nor
24: * may "Tigris" or "Axion" appear in their names without specific prior
25: * written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
30: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38: * =======================================================================
39: */
40:
41: package org.axiondb.constraints;
42:
43: import org.axiondb.AxionException;
44: import org.axiondb.RowDecorator;
45: import org.axiondb.RowIterator;
46: import org.axiondb.Table;
47: import org.axiondb.event.RowEvent;
48:
49: /**
50: * A NULL constraint, which is never violated but may be created and dropped.
51: *
52: * @version $Revision: 1.10 $ $Date: 2005/12/20 18:32:46 $
53: * @author Rodney Waldhoff
54: * @author Ahimanikya Satapathy
55: */
56: public class NullConstraint extends BaseSelectableBasedConstraint {
57: public NullConstraint() {
58: this (null);
59: }
60:
61: public NullConstraint(String name) {
62: super (name, "NULL");
63: }
64:
65: /** Returns <code>true</code>. */
66: public boolean evaluate(RowEvent event) throws AxionException {
67: return true;
68: }
69:
70: public boolean evaluate(RowEvent event, RowDecorator dec)
71: throws AxionException {
72: return true;
73: }
74:
75: public boolean evaluate(RowIterator oldRows, RowIterator newRows,
76: Table table) throws AxionException {
77: return true;
78: }
79:
80: private static final long serialVersionUID = 7642372780198639805L;
81: }
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