/libformula-1.1.3/source/org/pentaho/reporting/libraries/formula/function/information/IsBlankFunction.java

/*
 * 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 - 2009 Pentaho Corporation and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.formula.function.information;

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.ContextLookup;
import org.pentaho.reporting.libraries.formula.lvalues.LValue;
import org.pentaho.reporting.libraries.formula.lvalues.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.coretypes.LogicalType;

/**
 * Document me!
 * 
 * @author : Thomas Morgner
 */
public class IsBlankFunction implements Function
{
  private static final TypeValuePair RETURN_FALSE = new TypeValuePair(
      LogicalType.TYPE, Boolean.FALSE);

  private static final TypeValuePair RETURN_TRUE = new TypeValuePair(
      LogicalType.TYPE, Boolean.TRUE);
  private static final long serialVersionUID = 3352413434463488403L;

  public IsBlankFunction()
  {
  }

  public String getCanonicalName()
  {
    return "ISBLANK";
  }

  public TypeValuePair evaluate(final FormulaContext context,
      final ParameterCallback parameters) throws EvaluationException
  {
    final int parameterCount = parameters.getParameterCount();
    if (parameterCount < 1)
    {
      throw EvaluationException.getInstance(LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE);
    }
    final Object value = parameters.getValue(0);

    final LValue raw = parameters.getRaw(0);
    if (raw instanceof ContextLookup)
    {
      if (value == null)
      {
        return RETURN_TRUE;
      }
    }

    return RETURN_FALSE;
  }
}