001 /** 002 * ========================================= 003 * LibFormula : a free Java formula library 004 * ========================================= 005 * 006 * Project Info: http://reporting.pentaho.org/libformula/ 007 * 008 * (C) Copyright 2006-2007, by 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 * ------------ 027 * $Id: IsBlankFunction.java 3521 2007-10-16 10:55:14Z tmorgner $ 028 * ------------ 029 * (C) Copyright 2006-2007, by Pentaho Corporation. 030 */ 031 032 package org.jfree.formula.function.information; 033 034 import org.jfree.formula.EvaluationException; 035 import org.jfree.formula.FormulaContext; 036 import org.jfree.formula.LibFormulaErrorValue; 037 import org.jfree.formula.function.Function; 038 import org.jfree.formula.function.ParameterCallback; 039 import org.jfree.formula.lvalues.ContextLookup; 040 import org.jfree.formula.lvalues.LValue; 041 import org.jfree.formula.lvalues.TypeValuePair; 042 import org.jfree.formula.typing.coretypes.LogicalType; 043 044 /** 045 * Document me! 046 * 047 * @author : Thomas Morgner 048 */ 049 public class IsBlankFunction implements Function 050 { 051 private static final TypeValuePair RETURN_FALSE = new TypeValuePair( 052 LogicalType.TYPE, Boolean.FALSE); 053 054 private static final TypeValuePair RETURN_TRUE = new TypeValuePair( 055 LogicalType.TYPE, Boolean.TRUE); 056 057 public IsBlankFunction() 058 { 059 } 060 061 public String getCanonicalName() 062 { 063 return "ISBLANK"; 064 } 065 066 public TypeValuePair evaluate(final FormulaContext context, 067 final ParameterCallback parameters) throws EvaluationException 068 { 069 final int parameterCount = parameters.getParameterCount(); 070 if (parameterCount < 1) 071 { 072 throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE); 073 } 074 final Object value = parameters.getValue(0); 075 076 final LValue raw = parameters.getRaw(0); 077 if (raw instanceof ContextLookup) 078 { 079 if (value == null) 080 { 081 return RETURN_TRUE; 082 } 083 } 084 085 return RETURN_FALSE; 086 } 087 }