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: EvenFunction.java 3521 2007-10-16 10:55:14Z tmorgner $ 028 * ------------ 029 * (C) Copyright 2006-2007, by Pentaho Corporation. 030 */ 031 package org.jfree.formula.function.math; 032 033 import org.jfree.formula.EvaluationException; 034 import org.jfree.formula.FormulaContext; 035 import org.jfree.formula.LibFormulaErrorValue; 036 import org.jfree.formula.function.Function; 037 import org.jfree.formula.function.ParameterCallback; 038 import org.jfree.formula.lvalues.TypeValuePair; 039 import org.jfree.formula.typing.Type; 040 import org.jfree.formula.typing.coretypes.NumberType; 041 042 /** 043 * This function returns the rounding of a number up to the nearest even 044 * integer. 045 * 046 * @author Cedric Pronzato 047 * 048 */ 049 public class EvenFunction implements Function 050 { 051 052 public EvenFunction() 053 { 054 } 055 056 public TypeValuePair evaluate(final FormulaContext context, 057 final ParameterCallback parameters) throws EvaluationException 058 { 059 final int parameterCount = parameters.getParameterCount(); 060 if (parameterCount < 1) 061 { 062 throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE); 063 } 064 final Type type1 = parameters.getType(0); 065 final Object value1 = parameters.getValue(0); 066 final Number result = context.getTypeRegistry().convertToNumber(type1, 067 value1); 068 069 final int intValue = result.intValue(); 070 Integer ret; 071 072 int test = intValue; 073 if (intValue < 0) 074 { 075 test = intValue * -1; 076 } 077 078 if (test % 2 == 0) // even 079 { 080 if (intValue == 0) 081 { 082 if (result.doubleValue() < 0) 083 { 084 ret = new Integer(-2); 085 } 086 else if (result.doubleValue() > 0) 087 { 088 ret = new Integer(2); 089 } 090 else 091 { 092 ret = new Integer(0); 093 } 094 } 095 else 096 { 097 ret = new Integer(intValue); 098 } 099 } 100 else 101 // odd 102 { 103 if (result.doubleValue() < 0) 104 { 105 ret = new Integer(intValue - 1); 106 } 107 else 108 { 109 ret = new Integer(intValue + 1); 110 } 111 } 112 113 return new TypeValuePair(NumberType.GENERIC_NUMBER, ret); 114 } 115 116 public String getCanonicalName() 117 { 118 return "EVEN"; 119 } 120 121 }