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1: /** 2: * ========================================= 3: * LibFormula : a free Java formula library 4: * ========================================= 5: * 6: * Project Info: http://reporting.pentaho.org/libformula/ 7: * 8: * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors. 9: * 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: * ------------ 27: * $Id: IsBlankFunction.java 3521 2007-10-16 10:55:14Z tmorgner $ 28: * ------------ 29: * (C) Copyright 2006-2007, by Pentaho Corporation. 30: */ 31: 32: package org.jfree.formula.function.information; 33: 34: import org.jfree.formula.EvaluationException; 35: import org.jfree.formula.FormulaContext; 36: import org.jfree.formula.LibFormulaErrorValue; 37: import org.jfree.formula.function.Function; 38: import org.jfree.formula.function.ParameterCallback; 39: import org.jfree.formula.lvalues.ContextLookup; 40: import org.jfree.formula.lvalues.LValue; 41: import org.jfree.formula.lvalues.TypeValuePair; 42: import org.jfree.formula.typing.coretypes.LogicalType; 43: 44: /** 45: * Document me! 46: * 47: * @author : Thomas Morgner 48: */ 49: public class IsBlankFunction implements Function 50: { 51: private static final TypeValuePair RETURN_FALSE = new TypeValuePair( 52: LogicalType.TYPE, Boolean.FALSE); 53: 54: private static final TypeValuePair RETURN_TRUE = new TypeValuePair( 55: LogicalType.TYPE, Boolean.TRUE); 56: 57: public IsBlankFunction() 58: { 59: } 60: 61: public String getCanonicalName() 62: { 63: return "ISBLANK"; 64: } 65: 66: public TypeValuePair evaluate(final FormulaContext context, 67: final ParameterCallback parameters) throws EvaluationException 68: { 69: final int parameterCount = parameters.getParameterCount(); 70: if (parameterCount < 1) 71: { 72: throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE); 73: } 74: final Object value = parameters.getValue(0); 75: 76: final LValue raw = parameters.getRaw(0); 77: if (raw instanceof ContextLookup) 78: { 79: if (value == null) 80: { 81: return RETURN_TRUE; 82: } 83: } 84: 85: return RETURN_FALSE; 86: } 87: }