/**
* =========================================
* LibFormula : a free Java formula library
* =========================================
*
* Project Info: http://reporting.pentaho.org/libformula/
*
* (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
*
* This library is free software; you can redistribute it and/or modify it under the terms
* of the GNU Lesser General Public License as published by the Free Software Foundation;
* either version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
*
* ------------
* $Id: MidFunction.java 2752 2007-04-10 14:10:41Z taqua $
* ------------
* (C) Copyright 2006-2007, by Pentaho Corporation.
*/
package org.jfree.formula.function.text;
import org.jfree.formula.EvaluationException;
import org.jfree.formula.FormulaContext;
import org.jfree.formula.LibFormulaErrorValue;
import org.jfree.formula.function.Function;
import org.jfree.formula.function.ParameterCallback;
import org.jfree.formula.lvalues.TypeValuePair;
import org.jfree.formula.typing.Type;
import org.jfree.formula.typing.TypeRegistry;
import org.jfree.formula.typing.coretypes.TextType;
/**
* This function returns extracted text, given an original text, starting position, and length.
*
* @author Cedric Pronzato
*
*/
public class MidFunction implements Function
{
public MidFunction()
{
}
public TypeValuePair evaluate(final FormulaContext context,
final ParameterCallback parameters) throws EvaluationException
{
final int parameterCount = parameters.getParameterCount();
if (parameterCount != 3)
{
throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
}
final TypeRegistry typeRegistry = context.getTypeRegistry();
final Type textType = parameters.getType(0);
final Object textValue = parameters.getValue(0);
final Type startType = parameters.getType(1);
final Object startValue = parameters.getValue(1);
final Type lengthType = parameters.getType(2);
final Object lengthValue = parameters.getValue(2);
final String text = typeRegistry.convertToText(textType, textValue);
final Number start = typeRegistry.convertToNumber(startType, startValue);
final Number length = typeRegistry.convertToNumber(lengthType, lengthValue);
if(length.doubleValue() < 0 || start.doubleValue() < 1)
{
throw new EvaluationException(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
}
return new TypeValuePair(TextType.TYPE, process(text, start, length));
}
public String process(final String text, final Number start, final Number length)
{
int lengthValue = length.intValue();
final int startValue = start.intValue()-1;
if(startValue >= text.length())
{
return "";
}
if((lengthValue +startValue) > text.length())
{
lengthValue = text.length()-startValue;
}
return text.substring(startValue, startValue +lengthValue);
}
public String getCanonicalName()
{
return "MID";
}
}