Source for gnu.java.beans.encoder.ObjectId

   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: }