Source for org.jfree.formula.function.datetime.HourFunction

   1: /**
   2:  * =========================================
   3:  * LibFormula : a free Java formula library
   4:  * =========================================
   5:  *
   6:  * Project Info:  http://reporting.pentaho.org/libformula/
   7:  *
   8:  * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
   9:  *
  10:  * This library is free software; you can redistribute it and/or modify it under the terms
  11:  * of the GNU Lesser General Public License as published by the Free Software Foundation;
  12:  * either version 2.1 of the License, or (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  15:  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  16:  * See the GNU Lesser General Public License for more details.
  17:  *
  18:  * You should have received a copy of the GNU Lesser General Public License along with this
  19:  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20:  * Boston, MA 02111-1307, USA.
  21:  *
  22:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
  23:  * in the United States and other countries.]
  24:  *
  25:  *
  26:  * ------------
  27:  * $Id: HourFunction.java 2822 2007-05-20 21:47:52Z mimil $
  28:  * ------------
  29:  * (C) Copyright 2006-2007, by Pentaho Corporation.
  30:  */
  31: package org.jfree.formula.function.datetime;
  32: 
  33: import java.math.BigDecimal;
  34: 
  35: import org.jfree.formula.EvaluationException;
  36: import org.jfree.formula.FormulaContext;
  37: import org.jfree.formula.LibFormulaErrorValue;
  38: import org.jfree.formula.function.Function;
  39: import org.jfree.formula.function.ParameterCallback;
  40: import org.jfree.formula.lvalues.TypeValuePair;
  41: import org.jfree.formula.typing.TypeRegistry;
  42: import org.jfree.formula.typing.coretypes.NumberType;
  43: import org.jfree.formula.util.NumberUtil;
  44: 
  45: /**
  46:  * This function extracts the hour (0 through 23) from a time.
  47:  * 
  48:  * @author Cedric Pronzato
  49:  */
  50: public class HourFunction implements Function
  51: {
  52:   private static final BigDecimal HOUR_24 = new BigDecimal(24);
  53: 
  54:   public HourFunction()
  55:   {
  56:   }
  57: 
  58:   public String getCanonicalName()
  59:   {
  60:     return "HOUR";
  61:   }
  62: 
  63:   public TypeValuePair evaluate(final FormulaContext context,
  64:       final ParameterCallback parameters) throws EvaluationException
  65:   {
  66:     if (parameters.getParameterCount() != 1)
  67:     {
  68:       throw new EvaluationException(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
  69:     }
  70: 
  71:     final TypeRegistry typeRegistry = context.getTypeRegistry();
  72:     final Number n = typeRegistry.convertToNumber(parameters.getType(0),
  73:         parameters.getValue(0));
  74: 
  75:     if (n == null)
  76:     {
  77:       throw new EvaluationException(
  78:           LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
  79:     }
  80: 
  81:     final BigDecimal bd = NumberUtil.getAsBigDecimal(n);
  82:     final BigDecimal round1 = new BigDecimal(NumberUtil
  83:             .performIntRounding(bd).intValue());
  84:     final BigDecimal dayFraction = bd.subtract(round1);
  85:     final Integer hour = NumberUtil.performIntRounding(dayFraction
  86:         .multiply(HOUR_24));
  87: 
  88:     return new TypeValuePair(NumberType.GENERIC_NUMBER, hour);
  89:   }
  90: }