001    /* AccessibleRelationSet.java -- the combined relations of an accessible object
002       Copyright (C) 2002, 2005 Free Software Foundation
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package javax.accessibility;
039    
040    import gnu.java.lang.CPStringBuilder;
041    
042    import java.util.Locale;
043    import java.util.Vector;
044    
045    /**
046     * Describes all relations of an accessible object. For example, an object
047     * by labeled by one object and control another.
048     *
049     * @author Eric Blake (ebb9@email.byu.edu)
050     * @see AccessibleRelation
051     * @since 1.2
052     * @status updated to 1.4
053     */
054    public class AccessibleRelationSet
055    {
056      /**
057       * The list of relations, should be instances of AccessibleRelation. Don't
058       * set this to null.
059       *
060       * @see #add(AccessibleRelation)
061       * @see #addAll(AccessibleRelation[])
062       * @see #remove(AccessibleRelation)
063       * @see #contains(String)
064       * @see #get(String)
065       * @see #size()
066       * @see #toArray()
067       * @see #clear()
068       */
069      protected Vector<AccessibleRelation> relations
070        = new Vector<AccessibleRelation>();
071    
072      /**
073       * Create an empty relation set.
074       */
075      public AccessibleRelationSet()
076      {
077      }
078    
079      /**
080       * Create a relation set initialized with the given relations, duplicates are
081       * ignored.
082       *
083       * @param relations the relations to insert
084       * @throws NullPointerException if relations is null
085       */
086      public AccessibleRelationSet(AccessibleRelation[] relations)
087      {
088        addAll(relations);
089      }
090    
091      /**
092       * Add a new relation to the current set. If the relation is already in
093       * the set, the targets are merged with the existing relation, possibly
094       * resulting in an object being in the target list more than once. Do not
095       * add a relation with a null key, as it will cause problems later.
096       *
097       * @param relation the relation to add
098       * @return true if the set was modified, which is always the case
099       * @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