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: HourFunction.java 2822 2007-05-20 21:47:52Z mimil $
028 * ------------
029 * (C) Copyright 2006-2007, by Pentaho Corporation.
030 */
031 package org.jfree.formula.function.datetime;
032
033 import java.math.BigDecimal;
034
035 import org.jfree.formula.EvaluationException;
036 import org.jfree.formula.FormulaContext;
037 import org.jfree.formula.LibFormulaErrorValue;
038 import org.jfree.formula.function.Function;
039 import org.jfree.formula.function.ParameterCallback;
040 import org.jfree.formula.lvalues.TypeValuePair;
041 import org.jfree.formula.typing.TypeRegistry;
042 import org.jfree.formula.typing.coretypes.NumberType;
043 import org.jfree.formula.util.NumberUtil;
044
045 /**
046 * This function extracts the hour (0 through 23) from a time.
047 *
048 * @author Cedric Pronzato
049 */
050 public class HourFunction implements Function
051 {
052 private static final BigDecimal HOUR_24 = new BigDecimal(24);
053
054 public HourFunction()
055 {
056 }
057
058 public String getCanonicalName()
059 {
060 return "HOUR";
061 }
062
063 public TypeValuePair evaluate(final FormulaContext context,
064 final ParameterCallback parameters) throws EvaluationException
065 {
066 if (parameters.getParameterCount() != 1)
067 {
068 throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
069 }
070
071 final TypeRegistry typeRegistry = context.getTypeRegistry();
072 final Number n = typeRegistry.convertToNumber(parameters.getType(0),
073 parameters.getValue(0));
074
075 if (n == null)
076 {
077 throw new EvaluationException(
078 LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
079 }
080
081 final BigDecimal bd = NumberUtil.getAsBigDecimal(n);
082 final BigDecimal round1 = new BigDecimal(NumberUtil
083 .performIntRounding(bd).intValue());
084 final BigDecimal dayFraction = bd.subtract(round1);
085 final Integer hour = NumberUtil.performIntRounding(dayFraction
086 .multiply(HOUR_24));
087
088 return new TypeValuePair(NumberType.GENERIC_NUMBER, hour);
089 }
090 }