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: ExactFunction.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.text;
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.TypeRegistry;
041 import org.jfree.formula.typing.TypeConversionException;
042 import org.jfree.formula.typing.coretypes.LogicalType;
043
044 /**
045 * This function reports if two given text values are exactly equal using a case-sensitive comparison.
046 *
047 * @author Cedric Pronzato
048 *
049 */
050 public class ExactFunction implements Function
051 {
052 private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE);
053 private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE);
054
055 public ExactFunction()
056 {
057 }
058
059 public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
060 {
061 final int parameterCount = parameters.getParameterCount();
062 if (parameterCount != 2)
063 {
064 throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
065 }
066 final TypeRegistry typeRegistry = context.getTypeRegistry();
067
068 final Type textType1 = parameters.getType(0);
069 final Object textValue1 = parameters.getValue(0);
070 final Type textType2 = parameters.getType(1);
071 final Object textValue2 = parameters.getValue(1);
072
073
074 // Numerical comparisons ignore "trivial" differences that
075 // depend only on numeric precision of finite numbers.
076
077 // This fixes the common rounding errors, that are encountered when computing "((1/3) * 3)", which results
078 // in 0.99999 and not 1, as expected.
079 try
080 {
081 final Number number1 = typeRegistry.convertToNumber(textType1, textValue1);
082 final Number number2 = typeRegistry.convertToNumber(textType2, textValue2);
083
084 final double delta = Math.abs(Math.abs(number1.doubleValue()) - Math.abs(number2.doubleValue()));
085 if(delta < 0.00005)
086 {
087 return RETURN_TRUE;
088 }
089 return RETURN_FALSE;
090 }
091 catch(TypeConversionException tce)
092 {
093 // Ignore, try to compare them as strings ..
094 }
095
096 final String text1 = typeRegistry.convertToText(textType1, textValue1);
097 final String text2 = typeRegistry.convertToText(textType2, textValue2);
098 if(text1 == null || text2 == null)
099 {
100 throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
101 }
102
103 if (text1.equals(text2))
104 {
105 return RETURN_TRUE;
106 }
107 return RETURN_FALSE;
108 }
109
110 public String getCanonicalName()
111 {
112 return "EXACT";
113 }
114
115 }