/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* This program 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.
*
* Copyright (c) 2006 - 2013 Pentaho Corporation and Contributors. All rights reserved.
*/
package org.pentaho.reporting.libraries.formula.function.text;
import org.pentaho.reporting.libraries.formula.EvaluationException;
import org.pentaho.reporting.libraries.formula.FormulaContext;
import org.pentaho.reporting.libraries.formula.LibFormulaErrorValue;
import org.pentaho.reporting.libraries.formula.function.Function;
import org.pentaho.reporting.libraries.formula.function.ParameterCallback;
import org.pentaho.reporting.libraries.formula.lvalues.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.Type;
import org.pentaho.reporting.libraries.formula.typing.TypeRegistry;
import org.pentaho.reporting.libraries.formula.typing.coretypes.TextType;
/**
* This function returns a selected number of text characters from the left.<br/>
* This function depends on <code>MidFunction</code>.
*
* @see MidFunction
*
* @author Cedric Pronzato
*
*/
public class LeftFunction implements Function
{
private static final long serialVersionUID = 7929942586373275084L;
public LeftFunction()
{
}
public TypeValuePair evaluate(final FormulaContext context,
final ParameterCallback parameters) throws EvaluationException
{
final int parameterCount = parameters.getParameterCount();
if (parameterCount < 1 || parameterCount > 2)
{
throw EvaluationException.getInstance(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
}
final TypeRegistry typeRegistry = context.getTypeRegistry();
final Type textType = parameters.getType(0);
final Object textValue = parameters.getValue(0);
final String text = typeRegistry.convertToText(textType, textValue);
final int length;
if (parameterCount == 2)
{
final Type lengthType = parameters.getType(1);
final Object lengthValue = parameters.getValue(1);
final Number lengthConv = typeRegistry.convertToNumber(lengthType, lengthValue);
if (lengthConv.doubleValue() < 0)
{
throw EvaluationException.getInstance(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
}
length = lengthConv.intValue();
}
else
{
length = 1;
}
if (text == null)
{
throw EvaluationException.getInstance(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
}
// Note that MID(T;1;Length) produces the same results as LEFT(T;Length).
return new TypeValuePair(TextType.TYPE, MidFunction.process(text, 1, length));
}
public String getCanonicalName()
{
return "LEFT";
}
}