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: TrimFunction.java 3521 2007-10-16 10:55:14Z tmorgner $
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.coretypes.TextType;
041    
042    /**
043     * This function returns the given text free of leading spaces.
044     * Removes all leading and trailing spaces and all extra spaces inside the text.
045     *
046     * @author Cedric Pronzato
047     * @see http://mercury.ccil.org/%7Ecowan/OF/textfuncs.html
048     */
049    public class TrimFunction implements Function
050    {
051      public TrimFunction()
052      {
053      }
054    
055      public TypeValuePair evaluate(final FormulaContext context, final ParameterCallback parameters) throws EvaluationException
056      {
057        final int parameterCount = parameters.getParameterCount();
058        if (parameterCount < 1)
059        {
060          throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
061        }
062        final Type type1 = parameters.getType(0);
063        final Object value1 = parameters.getValue(0);
064        final String result = context.getTypeRegistry().convertToText(type1, value1);
065    
066        if(result == null)
067        {
068          throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
069        }
070    
071        // remove all unnecessary spaces ..
072        // we dont use regexps, because they are JDK 1.4, but this library is aimed
073        // for JDK 1.2.2
074    
075        final char[] chars = result.toCharArray();
076        final StringBuffer b = new StringBuffer(chars.length);
077        boolean removeNextWs = true;
078    
079        for (int i = 0; i < chars.length; i++)
080        {
081          final char c = chars[i];
082          if (Character.isWhitespace(c))
083          {
084            if (removeNextWs)
085            {
086              continue;
087            }
088            b.append(c);
089            removeNextWs = true;
090            continue;
091          }
092    
093          b.append(c);
094          removeNextWs = false;
095        }
096    
097        // now check whether the last char is a whitespace and remove that one
098        // if neccessary
099        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    }