gt:         if (this.xPosition == TimePeriodAnchor.START) {
context: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
   * in the United States and other countries.]
   *
   * -------------------------------
   * TimePeriodValuesCollection.java
   * -------------------------------
   * (C) Copyright 2003-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 22-Apr-2003 : Version 1 (DG);
   * 05-May-2004 : Now extends AbstractIntervalXYDataset (DG);
   * 15-Jul-2004 : Switched getX() with getXValue() and getY() with
   *               getYValue() (DG);
   * 06-Oct-2004 : Updated for changes in DomainInfo interface (DG);
   * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG);
   * ------------- JFREECHART 1.0.x ---------------------------------------------
   * 03-Oct-2006 : Deprecated get/setDomainIsPointsInTime() (DG);
   * 11-Jun-2007 : Fixed bug in getDomainBounds() method, and changed default
   *               value for domainIsPointsInTime to false (DG);
   *
   */
  
  package org.jfree.data.time;
  
  import java.io.Serializable;
  import java.util.Iterator;
  import java.util.List;
  
  import org.jfree.data.DomainInfo;
  import org.jfree.data.Range;
  import org.jfree.data.xy.AbstractIntervalXYDataset;
  import org.jfree.data.xy.IntervalXYDataset;
  import org.jfree.util.ObjectUtilities;
  
  /**
   * A collection of {@link TimePeriodValues} objects.
   * <P>
   * This class implements the {@link org.jfree.data.xy.XYDataset} interface, as
   * well as the extended {@link IntervalXYDataset} interface.  This makes it a
   * convenient dataset for use with the {@link org.jfree.chart.plot.XYPlot}
   * class.
   */
  public class TimePeriodValuesCollection extends AbstractIntervalXYDataset
          implements IntervalXYDataset, DomainInfo, Serializable {
  
      /** For serialization. */
      private static final long serialVersionUID = -3077934065236454199L;
  
      /** Storage for the time series. */
      private List data;
  
      /**
       * The position within a time period to return as the x-value (START,
       * MIDDLE or END).
       */
      private TimePeriodAnchor xPosition;
  
      /**
       * A flag that indicates that the domain is 'points in time'.  If this
       * flag is true, only the x-value is used to determine the range of values
       * in the domain, the start and end x-values are ignored.
       */
      private boolean domainIsPointsInTime;
  
      /**
       * Constructs an empty dataset.
       */
      public TimePeriodValuesCollection() {
          this((TimePeriodValues) null);
      }
  
      /**
       * Constructs a dataset containing a single series.  Additional series can
       * be added.
       *
       * @param series  the series (<code>null</code> ignored).
       */
      public TimePeriodValuesCollection(TimePeriodValues series) {
          this.data = new java.util.ArrayList();
          this.xPosition = TimePeriodAnchor.MIDDLE;
          this.domainIsPointsInTime = false;
          if (series != null) {
              this.data.add(series);
              series.addChangeListener(this);
          }
      }
  
      /**
       * Returns the position of the X value within each time period.
       *
       * @return The position (never <code>null</code>).
       *
       * @see #setXPosition(TimePeriodAnchor)
       */
      public TimePeriodAnchor getXPosition() {
          return this.xPosition;
      }
  
      /**
       * Sets the position of the x axis within each time period.
       *
       * @param position  the position (<code>null</code> not permitted).
       *
       * @see #getXPosition()
       */
      public void setXPosition(TimePeriodAnchor position) {
          if (position == null) {
              throw new IllegalArgumentException("Null 'position' argument.");
          }
          this.xPosition = position;
      }
  
      /**
       * Returns the number of series in the collection.
       *
       * @return The series count.
       */
      public int getSeriesCount() {
          return this.data.size();
      }
  
      /**
       * Returns a series.
       *
       * @param series  the index of the series (zero-based).
       *
       * @return The series.
       */
      public TimePeriodValues getSeries(int series) {
          if ((series < 0) || (series >= getSeriesCount())) {
              throw new IllegalArgumentException("Index 'series' out of range.");
          }
          return (TimePeriodValues) this.data.get(series);
      }
  
      /**
       * Returns the key for a series.
       *
       * @param series  the index of the series (zero-based).
       *
       * @return The key for a series.
       */
      public Comparable getSeriesKey(int series) {
          // defer argument checking
          return getSeries(series).getKey();
      }
  
      /**
       * Adds a series to the collection.  A
       * {@link org.jfree.data.general.DatasetChangeEvent} is sent to all
       * registered listeners.
       *
       * @param series  the time series.
       */
      public void addSeries(TimePeriodValues series) {
  
          if (series == null) {
              throw new IllegalArgumentException("Null 'series' argument.");
          }
  
          this.data.add(series);
          series.addChangeListener(this);
          fireDatasetChanged();
  
      }
  
      /**
       * Removes the specified series from the collection.
       *
       * @param series  the series to remove (<code>null</code> not permitted).
       */
      public void removeSeries(TimePeriodValues series) {
  
          if (series == null) {
              throw new IllegalArgumentException("Null 'series' argument.");
          }
          this.data.remove(series);
          series.removeChangeListener(this);
          fireDatasetChanged();
  
      }
  
      /**
       * Removes a series from the collection.
       *
       * @param index  the series index (zero-based).
       */
      public void removeSeries(int index) {
          TimePeriodValues series = getSeries(index);
          if (series != null) {
              removeSeries(series);
          }
      }
  
      /**
       * Returns the number of items in the specified series.
       * <P>
       * This method is provided for convenience.
       *
       * @param series  the index of the series of interest (zero-based).
       *
       * @return The number of items in the specified series.
       */
      public int getItemCount(int series) {
          return getSeries(series).getItemCount();
      }
  
      /**
       * Returns the x-value for the specified series and item.
       *
       * @param series  the series (zero-based index).
       * @param item  the item (zero-based index).
       *
       * @return The x-value for the specified series and item.
       */
      public Number getX(int series, int item) {
          TimePeriodValues ts = (TimePeriodValues) this.data.get(series);
          TimePeriodValue dp = ts.getDataItem(item);
          TimePeriod period = dp.getPeriod();
          return new Long(getX(period));
      }
  
      /**
       * Returns the x-value for a time period.
       *
       * @param period  the time period.
       *
       * @return The x-value.
       */
      private long getX(TimePeriod period) {
  
  