Source for org.jfree.formula.function.text.MidFunction

   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: MidFunction.java,v 1.5 2007/04/10 14:10:41 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.coretypes.TextType;
  42: 
  43: /**
  44:  * This function returns extracted text, given an original text, starting position, and length.
  45:  *
  46:  * @author Cedric Pronzato
  47:  *
  48:  */
  49: public class MidFunction implements Function
  50: {
  51:   public MidFunction()
  52:   {
  53:   }
  54: 
  55:   public TypeValuePair evaluate(final FormulaContext context,
  56:                                 final ParameterCallback parameters) throws EvaluationException
  57:   {
  58:     final int parameterCount = parameters.getParameterCount();
  59:     if (parameterCount != 3)
  60:     {
  61:       throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
  62:     }
  63:     final TypeRegistry typeRegistry = context.getTypeRegistry();
  64: 
  65:     final Type textType = parameters.getType(0);
  66:     final Object textValue = parameters.getValue(0);
  67:     final Type startType = parameters.getType(1);
  68:     final Object startValue = parameters.getValue(1);
  69:     final Type lengthType = parameters.getType(2);
  70:     final Object lengthValue = parameters.getValue(2);
  71: 
  72:     final String text = typeRegistry.convertToText(textType, textValue);
  73:     final Number start = typeRegistry.convertToNumber(startType, startValue);
  74:     final Number length = typeRegistry.convertToNumber(lengthType, lengthValue);
  75: 
  76:     if(length.doubleValue() < 0 || start.doubleValue() < 1)
  77:     {
  78:       throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
  79:     }
  80: 
  81:     return new TypeValuePair(TextType.TYPE, process(text, start, length));
  82:   }
  83: 
  84:   public String process(final String text, final Number start, final Number length)
  85:   {
  86:     int lengthValue = length.intValue();
  87:     final int startValue = start.intValue()-1;
  88:     if(startValue >= text.length())
  89:     {
  90:       return "";
  91:     }
  92: 
  93:     if((lengthValue +startValue) > text.length())
  94:     {
  95:       lengthValue = text.length()-startValue;
  96:     }
  97: 
  98:     return text.substring(startValue, startValue +lengthValue);
  99:   }
 100: 
 101:   public String getCanonicalName()
 102:   {
 103:     return "MID";
 104:   }
 105: