old-autovect-branch/libjava/classpath/gnu/CORBA/NamingService/NameComponentComparator.java

   1 /* NameComponentComparator.java --
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package gnu.CORBA.NamingService;
  40
  41 import org.omg.CORBA.BAD_PARAM;
  42 import org.omg.CosNaming.NameComponent;
  43
  44 import java.util.Comparator;
  45
  46 /**
  47  * This class implements the name component comparator, needed to
  48  * sort and compare the name components in maps and sorted sets.
  49  *
  50  * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
  51  */
  52 public final class NameComponentComparator
  53   implements Comparator
  54 {
  55   /**
  56    * The singleton instance of the name comparator.
  57    */
  58   public static final NameComponentComparator singleton = new NameComponentComparator();
  59
  60   /**
  61    * It is enough to have a singleton.
  62    */
  63   private NameComponentComparator()
  64   {
  65   }
  66
  67   /**
  68    * Compare the two names components.
  69    *
  70    * @param nc_a the first name component.
  71    * @param nc_b the second name component.
  72    *
  73    * @return 0 if the name components are equal, non zero value
  74    * as result of comparison otherwise.
  75    *
  76    * @throws BAD_PARAM if one of the components is empty or
  77    * has {@link NameComponent#id} or {@link NameComponent#kind}
  78    * field intialised to null.
  79    */
  80   public final int compare(Object nc_a, Object nc_b)
  81   {
  82     NameComponent a = (NameComponent) nc_a;
  83     NameComponent b = (NameComponent) nc_b;
  84
  85     int cn = a.id.compareTo(b.id);
  86     if (cn != 0)
  87       return cn;
  88     return a.kind.compareTo(b.kind);
  89   }
  90
  91   /**
  92    * All instances of this class are equal.
  93    */
  94   public boolean equals(Object x)
  95   {
  96     return x instanceof NameComponentComparator;
  97   }
  98 }