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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: ExactFunction.java,v 1.9 2007/05/08 09:47:09 taqua Exp $ 28: * ------------ 29: * (C) Copyright 2006-2007, by Pentaho Corporation. 30: */ 31: package org.jfree.formula.function.text; 32: 33: import org.jfree.formula.EvaluationException; 34: import org.jfree.formula.FormulaContext; 35: import org.jfree.formula.LibFormulaErrorValue; 36: import org.jfree.formula.function.Function; 37: import org.jfree.formula.function.ParameterCallback; 38: import org.jfree.formula.lvalues.TypeValuePair; 39: import org.jfree.formula.typing.Type; 40: import org.jfree.formula.typing.TypeRegistry; 41: import org.jfree.formula.typing.TypeConversionException; 42: import org.jfree.formula.typing.coretypes.LogicalType; 43: 44: /** 45: * This function reports if two given text values are exactly equal using a case-sensitive comparison. 46: * 47: * @author Cedric Pronzato 48: * 49: */ 50: public class ExactFunction implements Function 51: { 52: private static final TypeValuePair RETURN_FALSE = new TypeValuePair(LogicalType.TYPE, Boolean.FALSE); 53: private static final TypeValuePair RETURN_TRUE = new TypeValuePair(LogicalType.TYPE, Boolean.TRUE); 54: 55: public ExactFunction() 56: { 57: } 58: 59: public TypeValuePair evaluate(FormulaContext context, ParameterCallback parameters) throws EvaluationException 60: { 61: final int parameterCount = parameters.getParameterCount(); 62: if (parameterCount != 2) 63: { 64: throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE); 65: } 66: final TypeRegistry typeRegistry = context.getTypeRegistry(); 67: 68: final Type textType1 = parameters.getType(0); 69: final Object textValue1 = parameters.getValue(0); 70: final Type textType2 = parameters.getType(1); 71: final Object textValue2 = parameters.getValue(1); 72: 73: 74: // Numerical comparisons ignore "trivial" differences that 75: // depend only on numeric precision of finite numbers. 76: 77: // This fixes the common rounding errors, that are encountered when computing "((1/3) * 3)", which results 78: // in 0.99999 and not 1, as expected. 79: try 80: { 81: final Number number1 = typeRegistry.convertToNumber(textType1, textValue1); 82: final Number number2 = typeRegistry.convertToNumber(textType2, textValue2); 83: 84: final double delta = Math.abs(Math.abs(number1.doubleValue()) - Math.abs(number2.doubleValue())); 85: if(delta < 0.00005) 86: { 87: return RETURN_TRUE; 88: } 89: return RETURN_FALSE; 90: } 91: catch(TypeConversionException tce) 92: { 93: // Ignore, try to compare them as strings .. 94: } 95: 96: final String text1 = typeRegistry.convertToText(textType1, textValue1); 97: final String text2 = typeRegistry.convertToText(textType2, textValue2); 98: if(text1 == null || text2 == null) 99: { 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: