01: /**
02: * ========================================
03: * JFreeReport : a free Java report library
04: * ========================================
05: *
06: * Project Info: http://reporting.pentaho.org/
07: *
08: * (C) Copyright 2000-2007, by Object Refinery Limited, Pentaho Corporation and Contributors.
09: *
10: * This library is free software; you can redistribute it and/or modify it under the terms
11: * of the GNU Lesser General Public License as published by the Free Software Foundation;
12: * either version 2.1 of the License, or (at your option) any later version.
13: *
14: * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
15: * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16: * See the GNU Lesser General Public License for more details.
17: *
18: * You should have received a copy of the GNU Lesser General Public License along with this
19: * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20: * Boston, MA 02111-1307, USA.
21: *
22: * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
23: * in the United States and other countries.]
24: *
25: * ------------
26: * $Id: IsEmptyDataExpression.java 3048 2007-07-28 18:02:42Z tmorgner $
27: * ------------
28: * (C) Copyright 2000-2005, by Object Refinery Limited.
29: * (C) Copyright 2005-2007, by Pentaho Corporation.
30: */package org.jfree.report.expressions.sys;
31:
32: import org.jfree.report.DataSourceException;
33: import org.jfree.report.ReportData;
34: import org.jfree.report.expressions.AbstractExpression;
35: import org.jfree.report.expressions.ExpressionRuntime;
36:
37: /**
38: * Creation-Date: 31.01.2006, 18:55:09
39: *
40: * @author Thomas Morgner
41: */
42: public class IsEmptyDataExpression extends AbstractExpression {
43: public IsEmptyDataExpression() {
44: }
45:
46: /**
47: * Return the current expression value. <P> The value depends (obviously) on
48: * the expression implementation.
49: *
50: * @return the value of the function.
51: */
52: public Object computeValue() throws DataSourceException {
53:
54: final ExpressionRuntime runtime = getRuntime();
55: if (runtime == null) {
56: return null;
57: }
58:
59: final ReportData data = runtime.getData();
60: if (data == null) {
61: return null;
62: }
63: synchronized (data) {
64: if (data.getCursorPosition() > 0) {
65: return Boolean.FALSE;
66: }
67: if (data.isAdvanceable() == false) {
68: return Boolean.TRUE;
69: }
70: return Boolean.FALSE;
71: }
72: }
73: }
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