Package org.pentaho.reporting.engine.classic.core.filter

Source Code of org.pentaho.reporting.engine.classic.core.filter.FormatFilter

/*
* 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) 2001 - 2009 Object Refinery Ltd, Pentaho Corporation and Contributors..  All rights reserved.
*/

package org.pentaho.reporting.engine.classic.core.filter;

import java.text.Format;

import org.pentaho.reporting.engine.classic.core.Element;
import org.pentaho.reporting.engine.classic.core.function.ExpressionRuntime;
import org.pentaho.reporting.libraries.base.util.ObjectUtilities;

/**
* The base class for filters that format data.  Data is received from a DataSource and formatted. The data source might
* be a field in the TableModel or a report function, or even another format filter (since filters implement the
* DataSource interface).
* <p/>
* Formating is done by a java.text.Format object. This filter will always return a String object on getValue().
* <p/>
* If the formater does not understand the object returned by the defined datasource, the defined null value is
* returned.
* <p/>
* The nullValue is set to "-" by default.
*
* @author Thomas Morgner
*/
public class FormatFilter implements DataFilter, RawDataSource
{
  /**
   * The format used to create the string representation of the data.
   */
  private Format format;

  /**
   * The datasource from where the data is obtained.
   */
  private DataSource datasource;

  /**
   * The string used to represent null.
   */
  private String nullvalue;

  /**
   * A string holding the formatted result.
   */
  private transient String cachedResult;
  /**
   * The cached raw-value. This value is used to compare the incomming value with the cached result.
   */
  private transient Object cachedValue;
  /**
   * The cached Formatter.
   */
  private transient Format cachedFormat;

  /**
   * Default constructor.
   */
  public FormatFilter()
  {
    nullvalue = null;
  }

  /**
   * Clears all cached values and forces a complete recomputation of all formattings.
   */
  protected void invalidateCache()
  {
    cachedFormat = null;
    cachedValue = null;
    cachedResult = null;
  }

  /**
   * Sets the format for the filter.
   *
   * @param format The format.
   * @throws NullPointerException if the given format is null
   */
  public void setFormatter(final Format format)
  {
    if (format == null)
    {
      throw new NullPointerException();
    }
    this.format = format;
  }

  /**
   * Returns the format for the filter.
   *
   * @return The format.
   */
  public Format getFormatter()
  {
    return this.format;
  }

  /**
   * Returns the formatted string. The value is read using the data source given and formated using the formatter of
   * this object. The formating is guaranteed to completly form the object to an string or to return the defined
   * NullValue.
   * <p/>
   * If format, datasource or object are null, the NullValue is returned.
   *
   * @param runtime the expression runtime that is used to evaluate formulas and expressions when computing the value of
   *                this filter.
   * @param element
   * @return The formatted value.
   */
  public Object getValue(final ExpressionRuntime runtime, final Element element)
  {
    final Format f = getFormatter();
    if (f == null)
    {
      return getNullValue();
    }

    final DataSource ds = getDataSource();
    if (ds == null)
    {
      return getNullValue();
    }

    final Object o = ds.getValue(runtime, element);
    if (o == null)
    {
      return getNullValue();
    }

    if (cachedResult != null && (cachedFormat != f) &&
        ObjectUtilities.equal(cachedValue, o))
    {
      return cachedResult;
    }

    try
    {
      cachedResult = f.format(o);
    }
    catch (IllegalArgumentException e)
    {
      cachedResult = getNullValue();
    }

    cachedFormat = f;
    cachedValue = o;
    return cachedResult;
  }

  /**
   * Sets the value that will be displayed if the data source supplies a null value.
   *
   * @param nullvalue The string.
   */
  public void setNullValue(final String nullvalue)
  {
    if (nullvalue == null)
    {
      throw new NullPointerException();
    }
    this.nullvalue = nullvalue;
  }

  /**
   * Returns the string representing a null value from the data source.
   *
   * @return The string.
   */
  public String getNullValue()
  {
    return nullvalue;
  }

  /**
   * Returns the data source for the filter.
   *
   * @return The data source.
   */
  public DataSource getDataSource()
  {
    return datasource;
  }

  /**
   * Sets the data source.
   *
   * @param ds The data source.
   */
  public void setDataSource(final DataSource ds)
  {
    if (ds == null)
    {
      throw new NullPointerException();
    }
    this.datasource = ds;
  }

  /**
   * Clones the filter.
   *
   * @return a clone.
   * @throws CloneNotSupportedException this should never happen.
   */
  public Object clone()
      throws CloneNotSupportedException
  {
    final FormatFilter f = (FormatFilter) super.clone();
    if (datasource != null)
    {
      f.datasource = (DataSource) datasource.clone();
    }
    if (format != null)
    {
      f.format = (Format) format.clone();
      if (cachedFormat == format)
      {
        f.cachedFormat = f.format;
      }
    }
    return f;
  }

  public Object getRawValue(final ExpressionRuntime runtime, final Element element)
  {
    return datasource.getValue(runtime, element);
  }


  public FormatSpecification getFormatString(final ExpressionRuntime runtime,
                                             final Element element,
                                             FormatSpecification formatSpecification)
  {
    if (datasource instanceof RawDataSource)
    {
      final RawDataSource rds = (RawDataSource) datasource;
      return rds.getFormatString(runtime, element, formatSpecification);
    }
    if (formatSpecification == null)
    {
      formatSpecification = new FormatSpecification();
    }
    formatSpecification.redefine(FormatSpecification.TYPE_UNDEFINED, null);
    return formatSpecification;
  }

}
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