/* NameComponentComparator.java --
   Copyright (C) 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package gnu.CORBA.NamingService;

import org.omg.CORBA.BAD_PARAM;
import org.omg.CosNaming.NameComponent;

import java.util.Comparator;

/**
 * This class implements the name component comparator, needed to
 * sort and compare the name components in maps and sorted sets.
 *
 * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
 */
public final class NameComponentComparator
  implements Comparator
{
  /**
   * The singleton instance of the name comparator.
   */
  public static final NameComponentComparator singleton = new NameComponentComparator();

  /**
   * It is enough to have a singleton.
   */
  private NameComponentComparator()
  {
  }

  /**
   * Compare the two names components.
   *
   * @param nc_a the first name component.
   * @param nc_b the second name component.
   *
   * @return 0 if the name components are equal, non zero value
   * as result of comparison otherwise.
   *
   * @throws BAD_PARAM if one of the components is empty or
   * has {@link NameComponent#id} or {@link NameComponent#kind}
   * field intialised to null.
   */
  public final int compare(Object nc_a, Object nc_b)
  {
    NameComponent a = (NameComponent) nc_a;
    NameComponent b = (NameComponent) nc_b;

    int cn = a.id.compareTo(b.id);
    if (cn != 0)
      return cn;
    return a.kind.compareTo(b.kind);
  }

  /**
   * All instances of this class are equal.
   */
  public boolean equals(Object x)
  {
    return x instanceof NameComponentComparator;
  }
}