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 }