libjava/classpath/gnu/java/beans/encoder/ObjectId.java

   1 /* ObjectId.java -- Simple object identification mechanism for XML encoding.
   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.java.beans.encoder;
  40
  41 import java.util.HashMap;
  42
  43 /**
  44  * <p>
  45  * ObjectId provides an object identification mechanism which gives each object
  46  * a name in the form <code>&lt;class&gt;&lt;Nameindex&gt;</code>.
  47  * </p>
  48  *
  49  * <p>
  50  * Each id can be in an unused state which means that only one instance of the
  51  * object is in use and a special id is not needed. Certain {@link
  52  * gnu.java.beans.encoder.elements.Element} subclasses use this feature to find
  53  * out whether they write the "id" attribute or not.
  54  * </p>
  55  * <p>
  56  * An <code>ObjectId</code> instance is typically given to multiple objects.
  57  * The second user should then invoke the {@link #init} method to generate the
  58  * identification string and bring the id in the 'used' state.
  59  * </p>
  60  *
  61  * @author Robert Schuster (robertschuster@fsfe.org)
  62  */
  63 public class ObjectId
  64 {
  65   /**
  66    * Stores the index an object of a specific type should be given.
  67    */
  68   private static HashMap nameIndices = new HashMap();
  69
  70   private String id;
  71
  72   private Class klass;
  73
  74   ObjectId(Class klass)
  75   {
  76     this.klass = klass;
  77   }
  78
  79   public boolean isUnused()
  80   {
  81     return id == null;
  82   }
  83
  84   public String toString()
  85   {
  86     return (id != null) ? id : "<unused id>";
  87   }
  88
  89   /**
  90    * <p>
  91    * Generates a simple Id by concatenating a class name with a self-increasing
  92    * number.
  93    * </p>
  94    */
  95   public void init()
  96   {
  97     assert (klass != null);
  98
  99     if (id != null)
 100       return;
 101
 102     Integer count = (Integer) nameIndices.get(klass);
 103     if (count == null)
 104       {
 105         count = Integer.valueOf(0);
 106       }
 107
 108     if (klass.isArray())
 109       {
 110         Class ct = klass.getComponentType();
 111         if (ct == Boolean.TYPE)
 112           id = "booleanArray" + count.intValue();
 113         else if (ct == Byte.TYPE)
 114           id = "byteArray" + count.intValue();
 115         else if (ct == Short.TYPE)
 116           id = "shortArray" + count.intValue();
 117         else if (ct == Integer.TYPE)
 118           id = "intArray" + count.intValue();
 119         else if (ct == Long.TYPE)
 120           id = "longArray" + count.intValue();
 121         else if (ct == Float.TYPE)
 122           id = "floatArray" + count.intValue();
 123         else if (ct == Double.TYPE)
 124           id = "doubleArray" + count.intValue();
 125       }
 126     else
 127       id = klass.getName() + count.intValue();
 128
 129     nameIndices.put(klass, Integer.valueOf(count.intValue() + 1));
 130   }
 131
 132 }