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
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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