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: MidFunction.java 2752 2007-04-10 14:10:41Z taqua $ 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.coretypes.TextType; 042 043 /** 044 * This function returns extracted text, given an original text, starting position, and length. 045 * 046 * @author Cedric Pronzato 047 * 048 */ 049 public class MidFunction implements Function 050 { 051 public MidFunction() 052 { 053 } 054 055 public TypeValuePair evaluate(final FormulaContext context, 056 final ParameterCallback parameters) throws EvaluationException 057 { 058 final int parameterCount = parameters.getParameterCount(); 059 if (parameterCount != 3) 060 { 061 throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE); 062 } 063 final TypeRegistry typeRegistry = context.getTypeRegistry(); 064 065 final Type textType = parameters.getType(0); 066 final Object textValue = parameters.getValue(0); 067 final Type startType = parameters.getType(1); 068 final Object startValue = parameters.getValue(1); 069 final Type lengthType = parameters.getType(2); 070 final Object lengthValue = parameters.getValue(2); 071 072 final String text = typeRegistry.convertToText(textType, textValue); 073 final Number start = typeRegistry.convertToNumber(startType, startValue); 074 final Number length = typeRegistry.convertToNumber(lengthType, lengthValue); 075 076 if(length.doubleValue() < 0 || start.doubleValue() < 1) 077 { 078 throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE); 079 } 080 081 return new TypeValuePair(TextType.TYPE, process(text, start, length)); 082 } 083 084 public String process(final String text, final Number start, final Number length) 085 { 086 int lengthValue = length.intValue(); 087 final int startValue = start.intValue()-1; 088 if(startValue >= text.length()) 089 { 090 return ""; 091 } 092 093 if((lengthValue +startValue) > text.length()) 094 { 095 lengthValue = text.length()-startValue; 096 } 097 098 return text.substring(startValue, startValue +lengthValue); 099 } 100 101 public String getCanonicalName() 102 { 103 return "MID"; 104 } 105 106 }