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 }