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JChart2D is an easy to use component for displaying two- dimensional traces in a coordinate system written in Java.
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/*
 * Trace2DBijective, a list- based implementation of a ITrace2D that only
 *  allows a single occurance of a certain x- value.
 * Copyright (c) 2004 - 2011  Achim Westermann, [email protected]
 *
 *  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 St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *  If you modify or optimize the code in a useful way please let me know.
 *  [email protected]
 */

package info.monitorenter.gui.chart.traces;

import info.monitorenter.gui.chart.ITracePoint2D;

import java.util.Iterator;

/**
 * A  Trace2D who only allows a single occurance of a tracepoint
 * with a certain x- value xi. 

 * 
 * From y1 = f(x1) = f(x2)  follows: x1==x2  (injective) 

 * For every y- value yi contained there exists at least one value xi
 * (surjective) 

 * Both qualities joined result in a bijective assignment between x and y
 * values.
 * 
 * 
 * The policy for both addPoint- methods is implemented as
 * follows: 

 * 

 * Every point whose x- value is not contained yet is appended at the end
 * of the internal list.
 * If the x- value is contained before, the tracepoint with that value is
 * removed and the new point is added to the end of the internal list. In
 * that case the new tracepoint is not inserted at the location where the old
 * point used to be! 
 * 
 * 
 * 
 * @author Achim Westermann [email protected] 
 * 
 * @version $Revision: 1.15 $
 */
public class Trace2DBijective
    extends Trace2DSimple {

  /** Generated serialVersionUID. */
  private static final long serialVersionUID = 2913093358404794473L;

  /**
   * Defcon of this stateless instance.
   */
  public Trace2DBijective() {
    // nop
  }

  /**
   * @see info.monitorenter.gui.chart.traces.Trace2DSimple#addPointInternal(info.monitorenter.gui.chart.ITracePoint2D)
   */
  @Override
  protected boolean addPointInternal(final ITracePoint2D p) {
    boolean result = false;
    double px = p.getX();
    synchronized (this) {
      Iterator it = this.m_points.iterator();
      ITracePoint2D tmp = null;
      ITracePoint2D removed = null;
      while (it.hasNext()) {
        tmp = it.next();
        if (tmp.getX() == px) {
          it.remove();
          removed = tmp;
          break;
        }
      }
      if (removed != null) {
        this.removePoint(removed);
        // don't use bound check routines of calling addPoint.
        result = false;
      }
      result = super.addPointInternal(p);
    }
    return result;
  }
}