libjava/javax/accessibility/AccessibleRelationSet.java

   1 /* AccessibleRelationSet.java -- the combined relations of an accessible object
   2    Copyright (C) 2002 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 java.util.Vector;
  41
  42 /**
  43  * Describes all relations of an accessible object. For example, an object
  44  * by labeled by one object and control another.
  45  *
  46  * @author Eric Blake (ebb9@email.byu.edu)
  47  * @see AccessibleRelation
  48  * @since 1.2
  49  * @status updated to 1.4
  50  */
  51 public class AccessibleRelationSet
  52 {
  53   /**
  54    * The list of relations, should be instances of AccessibleRelation. Don't
  55    * set this to null.
  56    *
  57    * @see #add(AccessibleRelation)
  58    * @see #addAll(AccessibleRelation[])
  59    * @see #remove(AccessibleRelation)
  60    * @see #contains(String)
  61    * @see #get(String)
  62    * @see #size()
  63    * @see #toArray()
  64    * @see #clear()
  65    */
  66   protected Vector relations = new Vector();
  67
  68   /**
  69    * Create an empty relation set.
  70    */
  71   public AccessibleRelationSet()
  72   {
  73   }
  74
  75   /**
  76    * Create a relation set initialized with the given relations, duplicates are
  77    * ignored.
  78    *
  79    * @param relations the relations to insert
  80    * @throws NullPointerException if relations is null
  81    */
  82   public AccessibleRelationSet(AccessibleRelation[] relations)
  83   {
  84     addAll(relations);
  85   }
  86
  87   /**
  88    * Add a new relation to the current set. If the relation is already in
  89    * the set, the targets are merged with the existing relation, possibly
  90    * resulting in an object being in the target list more than once. Do not
  91    * add a relation with a null key, as it will cause problems later.
  92    *
  93    * @param relation the relation to add
  94    * @return true if the set was modified, which is always the case
  95    * @throws NullPointerException if relation is null
  96    */
  97   public boolean add(AccessibleRelation relation)
  98   {
  99     AccessibleRelation old = get(relation.key);
 100     if (old == null)
 101       return relations.add(relation);
 102     if (old.targets.length == 0)
 103       old.targets = relation.targets;
 104     else if (relation.targets.length != 0)
 105       {
 106         Object[] t = new Object[old.targets.length + relation.targets.length];
 107         System.arraycopy(old.targets, 0, t, 0, old.targets.length);
 108         System.arraycopy(relation.targets, 0, t, old.targets.length,
 109                          relation.targets.length);
 110         old.targets = t;
 111       }
 112     return true;
 113   }
 114
 115   /**
 116    * Add all of the relations to the current set. Duplicates are ignored.
 117    *
 118    * @param array the array of relations to add
 119    * @throws NullPointerException if array is null or has null entries
 120    */
 121   public void addAll(AccessibleRelation[] array)
 122   {
 123     int i = array.length;
 124     while (--i >= 0)
 125       add(array[i]);
 126   }
 127
 128   /**
 129    * Remove a relation from the set. If a relation was removed, return true.
 130    * Note that this uses AccessibleRelation.equals, which defaults to ==, so a
 131    * relation with the same key may still exist in the set afterwords.
 132    *
 133    * @param relation the state to remove
 134    * @return true if the set changed
 135    */
 136   public boolean remove(AccessibleRelation relation)
 137   {
 138     return relations.remove(relation);
 139   }
 140
 141   /**
 142    * Clear all relations in the set.
 143    */
 144   public void clear()
 145   {
 146     relations.clear();
 147   }
 148
 149   /**
 150    * Return the number of relations in the set.
 151    *
 152    * @return the set size
 153    */
 154   public int size()
 155   {
 156     return relations.size();
 157   }
 158
 159   /**
 160    * Check if the relation key is in the set.
 161    *
 162    * @param relation the relation to locate
 163    * @return true if it is in the set
 164    */
 165   public boolean contains(String key)
 166   {
 167     int i = relations.size();
 168     while (--i >= 0)
 169       if (((AccessibleRelation) relations.get(i)).key.equals(key))
 170         return true;
 171     return false;
 172   }
 173
 174   /**
 175    * Get the relation that matches the key.
 176    *
 177    * @param relation the relation to locate
 178    * @return the relation in the set, or null
 179    */
 180   public AccessibleRelation get(String key)
 181   {
 182     int i = relations.size();
 183     while (--i >= 0)
 184       {
 185         AccessibleRelation r = (AccessibleRelation) relations.get(i);
 186         if (r.key.equals(key))
 187           return r;
 188       }
 189     return null;
 190   }
 191
 192   /**
 193    * Return the relation set as an array.
 194    *
 195    * @return an array of the current relations
 196    */
 197   public AccessibleRelation[] toArray()
 198   {
 199     AccessibleRelation[] result = new AccessibleRelation[relations.size()];
 200     relations.toArray(result);
 201     return result;
 202   }
 203
 204   /**
 205    * Return a localized, comma-separated string representing all relations
 206    * in the set. This is in arbitrary order.
 207    *
 208    * @return the string representation
 209    * @see AccessibleBundle#toDisplayString(String, Locale)
 210    */
 211   public String toString()
 212   {
 213     int i = relations.size();
 214     if (i == 0)
 215       return "";
 216     // Pre-allocate an average of 10 chars per state.
 217     StringBuffer b = new StringBuffer(i * 10);
 218     while (--i >= 0)
 219       b.append(relations.get(i)).append(',');
 220     return b.substring(0, b.length() - 1);
 221   }
 222 } // class AccessibleRelationSet