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 }