001 /** 002 * ======================================== 003 * JFreeReport : a free Java report library 004 * ======================================== 005 * 006 * Project Info: http://reporting.pentaho.org/ 007 * 008 * (C) Copyright 2000-2007, by Object Refinery Limited, Pentaho Corporation and Contributors. 009 * 010 * This library is free software; you can redistribute it and/or modify it under the terms 011 * of the GNU Lesser General Public License as published by the Free Software Foundation; 012 * either version 2.1 of the License, or (at your option) any later version. 013 * 014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 016 * See the GNU Lesser General Public License for more details. 017 * 018 * You should have received a copy of the GNU Lesser General Public License along with this 019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, 020 * Boston, MA 02111-1307, USA. 021 * 022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 023 * in the United States and other countries.] 024 * 025 * ------------ 026 * $Id: IsEmptyDataExpression.java 3048 2007-07-28 18:02:42Z tmorgner $ 027 * ------------ 028 * (C) Copyright 2000-2005, by Object Refinery Limited. 029 * (C) Copyright 2005-2007, by Pentaho Corporation. 030 */ 031 package org.jfree.report.expressions.sys; 032 033 import org.jfree.report.DataSourceException; 034 import org.jfree.report.ReportData; 035 import org.jfree.report.expressions.AbstractExpression; 036 import org.jfree.report.expressions.ExpressionRuntime; 037 038 /** 039 * Creation-Date: 31.01.2006, 18:55:09 040 * 041 * @author Thomas Morgner 042 */ 043 public class IsEmptyDataExpression extends AbstractExpression 044 { 045 public IsEmptyDataExpression() 046 { 047 } 048 049 /** 050 * Return the current expression value. <P> The value depends (obviously) on 051 * the expression implementation. 052 * 053 * @return the value of the function. 054 */ 055 public Object computeValue() throws DataSourceException 056 { 057 058 final ExpressionRuntime runtime = getRuntime(); 059 if (runtime == null) 060 { 061 return null; 062 } 063 064 final ReportData data = runtime.getData(); 065 if (data == null) 066 { 067 return null; 068 } 069 synchronized(data) 070 { 071 if (data.getCursorPosition() > 0) 072 { 073 return Boolean.FALSE; 074 } 075 if (data.isAdvanceable() == false) 076 { 077 return Boolean.TRUE; 078 } 079 return Boolean.FALSE; 080 } 081 } 082 }