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 }