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

   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: TrimFunction.java 3521 2007-10-16 10:55:14Z tmorgner $
  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.coretypes.TextType;
  41: 
  42: /**
  43:  * This function returns the given text free of leading spaces.
  44:  * Removes all leading and trailing spaces and all extra spaces inside the text.
  45:  *
  46:  * @author Cedric Pronzato
  47:  * @see http://mercury.ccil.org/%7Ecowan/OF/textfuncs.html
  48:  */
  49: public class TrimFunction implements Function
  50: {
  51:   public TrimFunction()
  52:   {
  53:   }
  54: 
  55:   public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
  56:   {
  57:     final int parameterCount = parameters.getParameterCount();
  58:     if (parameterCount < 1)
  59:     {
  60:       throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
  61:     }
  62:     final Type type1 = parameters.getType(0);
  63:     final Object value1 = parameters.getValue(0);
  64:     final String result = context.getTypeRegistry().convertToText(type1, value1);
  65: 
  66:     if(result == null)
  67:     {
  68:       throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
  69:     }
  70: 
  71:     // remove all unnecessary spaces ..
  72:     // we dont use regexps, because they are JDK 1.4, but this library is aimed
  73:     // for JDK 1.2.2
  74: 
  75:     final char[] chars = result.toCharArray();
  76:     final StringBuffer b = new StringBuffer(chars.length);
  77:     boolean removeNextWs = true;
  78: 
  79:     for (int i = 0; i < chars.length; i++)
  80:     {
  81:       final char c = chars[i];
  82:       if (Character.isWhitespace(c))
  83:       {
  84:         if (removeNextWs)
  85:         {
  86:           continue;
  87:         }
  88:         b.append(c);
  89:         removeNextWs = true;
  90:         continue;
  91:       }
  92: 
  93:       b.append(c);
  94:       removeNextWs = false;
  95:     }
  96: 
  97:     // now check whether the last char is a whitespace and remove that one
  98:     // if neccessary
  99:     final String trimmedResult;
 100:     if (removeNextWs)
 101:     {
 102:       trimmedResult = b.substring(0, b.length() - 1);
 103:     }
 104:     else
 105:     {
 106:       trimmedResult = b.toString();
 107:     }
 108: 
 109:     return new TypeValuePair(TextType.TYPE, trimmedResult);
 110:   }
 111: 
 112:   public String getCanonicalName()
 113:   {
 114:     return "TRIM";
 115:   }
 116: 
 117: }