/**
* =========================================
* 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: HourFunction.java,v 1.1 2007/05/20 21:47:52 mimil Exp $
* ------------
* (C) Copyright 2006-2007, by Pentaho Corporation.
*/
package org.jfree.formula.function.datetime;
import java.math.BigDecimal;
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.TypeRegistry;
import org.jfree.formula.typing.coretypes.NumberType;
import org.jfree.formula.util.NumberUtil;
/**
* This function extracts the hour (0 through 23) from a time.
*
* @author Cedric Pronzato
*/
public class HourFunction implements Function
{
private static final BigDecimal HOUR_24 = new BigDecimal(24);
public HourFunction()
{
}
public String getCanonicalName()
{
return "HOUR";
}
public TypeValuePair evaluate(final FormulaContext context,
final ParameterCallback parameters) throws EvaluationException
{
if (parameters.getParameterCount() != 1)
{
throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
}
final TypeRegistry typeRegistry = context.getTypeRegistry();
final Number n = typeRegistry.convertToNumber(parameters.getType(0),
parameters.getValue(0));
if (n == null)
{
throw new EvaluationException(
LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
}
final BigDecimal bd = NumberUtil.getAsBigDecimal(n);
final BigDecimal round1 = new BigDecimal(NumberUtil
.performIntRounding(bd).intValue());
final BigDecimal dayFraction = bd.subtract(round1);
final Integer hour = NumberUtil.performIntRounding(dayFraction
.multiply(HOUR_24));
return new TypeValuePair(NumberType.GENERIC_NUMBER, hour);
}
}