libjava/classpath/javax/accessibility/AccessibleRelationSet.java

   1 /* AccessibleRelationSet.java -- the combined relations of an accessible object
   2    Copyright (C) 2002, 2005 Free Software Foundation
   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 package javax.accessibility;
  39
  40 import gnu.java.lang.CPStringBuilder;
  41
  42 import java.util.Locale;
  43 import java.util.Vector;
  44
  45 /**
  46  * Describes all relations of an accessible object. For example, an object
  47  * by labeled by one object and control another.
  48  *
  49  * @author Eric Blake (ebb9@email.byu.edu)
  50  * @see AccessibleRelation
  51  * @since 1.2
  52  * @status updated to 1.4
  53  */
  54 public class AccessibleRelationSet
  55 {
  56   /**
  57    * The list of relations, should be instances of AccessibleRelation. Don't
  58    * set this to null.
  59    *
  60    * @see #add(AccessibleRelation)
  61    * @see #addAll(AccessibleRelation[])
  62    * @see #remove(AccessibleRelation)
  63    * @see #contains(String)
  64    * @see #get(String)
  65    * @see #size()
  66    * @see #toArray()
  67    * @see #clear()
  68    */
  69   protected Vector<AccessibleRelation> relations
  70     = new Vector<AccessibleRelation>();
  71
  72   /**
  73    * Create an empty relation set.
  74    */
  75   public AccessibleRelationSet()
  76   {
  77   }
  78
  79   /**
  80    * Create a relation set initialized with the given relations, duplicates are
  81    * ignored.
  82    *
  83    * @param relations the relations to insert
  84    * @throws NullPointerException if relations is null
  85    */
  86   public AccessibleRelationSet(AccessibleRelation[] relations)
  87   {
  88     addAll(relations);
  89   }
  90
  91   /**
  92    * Add a new relation to the current set. If the relation is already in
  93    * the set, the targets are merged with the existing relation, possibly
  94    * resulting in an object being in the target list more than once. Do not
  95    * add a relation with a null key, as it will cause problems later.
  96    *
  97    * @param relation the relation to add
  98    * @return true if the set was modified, which is always the case
  99    * @throws NullPointerException if relation is null
 100    */
 101   public boolean add(AccessibleRelation relation)
 102   {
 103     AccessibleRelation old = get(relation.key);
 104     if (old == null)
 105       return relations.add(relation);
 106     if (old.targets.length == 0)
 107       old.targets = relation.targets;
 108     else if (relation.targets.length != 0)
 109       {
 110         Object[] t = new Object[old.targets.length + relation.targets.length];
 111         System.arraycopy(old.targets, 0, t, 0, old.targets.length);
 112         System.arraycopy(relation.targets, 0, t, old.targets.length,
 113                          relation.targets.length);
 114         old.targets = t;
 115       }
 116     return true;
 117   }
 118
 119   /**
 120    * Add all of the relations to the current set. Duplicates are ignored.
 121    *
 122    * @param array the array of relations to add
 123    * @throws NullPointerException if array is null or has null entries
 124    */
 125   public void addAll(AccessibleRelation[] array)
 126   {
 127     int i = array.length;
 128     while (--i >= 0)
 129       add(array[i]);
 130   }
 131
 132   /**
 133    * Remove a relation from the set. If a relation was removed, return true.
 134    * Note that this uses AccessibleRelation.equals, which defaults to ==, so a
 135    * relation with the same key may still exist in the set afterwords.
 136    *
 137    * @param relation the state to remove
 138    * @return true if the set changed
 139    */
 140   public boolean remove(AccessibleRelation relation)
 141   {
 142     return relations.remove(relation);
 143   }
 144
 145   /**
 146    * Clear all relations in the set.
 147    */
 148   public void clear()
 149   {
 150     relations.clear();
 151   }
 152
 153   /**
 154    * Return the number of relations in the set.
 155    *
 156    * @return the set size
 157    */
 158   public int size()
 159   {
 160     return relations.size();
 161   }
 162
 163   /**
 164    * Check if the relation key is in the set.
 165    *
 166    * @param key the relation to locate
 167    * @return true if it is in the set
 168    */
 169   public boolean contains(String key)
 170   {
 171     int i = relations.size();
 172     while (--i >= 0)
 173       if ((relations.get(i)).key.equals(key))
 174         return true;
 175     return false;
 176   }
 177
 178   /**
 179    * Get the relation that matches the key.
 180    *
 181    * @param key the relation to locate
 182    * @return the relation in the set, or null
 183    */
 184   public AccessibleRelation get(String key)
 185   {
 186     int i = relations.size();
 187     while (--i >= 0)
 188       {
 189         AccessibleRelation r = relations.get(i);
 190         if (r.key.equals(key))
 191           return r;
 192       }
 193     return null;
 194   }
 195
 196   /**
 197    * Return the relation set as an array.
 198    *
 199    * @return an array of the current relations
 200    */
 201   public AccessibleRelation[] toArray()
 202   {
 203     AccessibleRelation[] result = new AccessibleRelation[relations.size()];
 204     relations.toArray(result);
 205     return result;
 206   }
 207
 208   /**
 209    * Return a localized, comma-separated string representing all relations
 210    * in the set. This is in arbitrary order.
 211    *
 212    * @return the string representation
 213    * @see AccessibleBundle#toDisplayString(String, Locale)
 214    */
 215   public String toString()
 216   {
 217     int i = relations.size();
 218     if (i == 0)
 219       return "";
 220     // Pre-allocate an average of 10 chars per state.
 221     CPStringBuilder b = new CPStringBuilder(i * 10);
 222     while (--i >= 0)
 223       b.append(relations.get(i)).append(',');
 224     return b.substring(0, b.length() - 1);
 225   }
 226 } // class AccessibleRelationSet