001    /* InputMap.java --
002       Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.
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.swing;
039    
040    import java.io.Serializable;
041    import java.util.Arrays;
042    import java.util.HashMap;
043    import java.util.HashSet;
044    import java.util.Map;
045    import java.util.Set;
046    
047    /**
048     * Maps {@link KeyStroke}s to arbitrary objects, usually Strings. This
049     * is used in combination with {@link ActionMap}s.
050     *
051     * If a component receives an input event, this is looked up in
052     * the component's <code>InputMap</code>. The result is an object which
053     * serves as a key to the component's <code>ActionMap</code>. Finally
054     * the <code>Action</code> that is stored is executed.
055     *
056     * @author Andrew Selkirk
057     * @author Michael Koch
058     *
059     * @since 1.3
060     */
061    public class InputMap
062      implements Serializable
063    {
064      private static final long serialVersionUID = -5429059542008604257L;
065    
066      /**
067       * Storage for the KeyStroke --> Object mappings.
068       */
069      private Map inputMap;
070    
071      /**
072       * An optional parent map.
073       */
074      private InputMap parent;
075    
076      /**
077       * Creates a new <code>InputMap</code> instance.  This default instance
078       * contains no mappings and has no parent.
079       */
080      public InputMap()
081      {
082        // nothing to do
083      }
084    
085      /**
086       * Returns the binding for the specified keystroke, if there is one.
087       *
088       * @param keystroke the key of the entry (<code>null</code> is ignored).
089       *
090       * @return The binding associated with the specified keystroke (or
091       *     <code>null</code>).
092       */
093      public Object get(KeyStroke keystroke)
094      {
095        Object result = null;
096        if (inputMap != null)
097          result = inputMap.get(keystroke);
098    
099        if (result == null && parent != null)
100          result = parent.get(keystroke);
101        return result;
102      }
103    
104      /**
105       * Puts a new entry into the <code>InputMap</code>.  If
106       * <code>actionMapKey</code> is <code>null</code> any existing entry will be
107       * removed.
108       *
109       * @param keystroke the keystroke for the entry (<code>null</code> is
110       *     ignored).
111       * @param actionMapKey the action (<code>null</code> permitted).
112       */
113      public void put(KeyStroke keystroke, Object actionMapKey)
114      {
115        if (keystroke == null)
116          return;
117        if (inputMap == null)
118          inputMap = new HashMap();
119        if (actionMapKey == null)
120          inputMap.remove(keystroke);
121        else
122          inputMap.put(keystroke, actionMapKey);
123      }
124    
125      /**
126       * Removes an entry from this <code>InputMap</code>.  Note that this will
127       * not remove any entry from the parent map, if there is one.
128       *
129       * @param keystroke the key of the entry to remove (<code>null</code> is
130       *     ignored).
131       */
132      public void remove(KeyStroke keystroke)
133      {
134        if (inputMap != null)
135          inputMap.remove(keystroke);
136      }
137    
138      /**
139       * Returns the parent of this <code>InputMap</code>.  The default value
140       * is <code>null</code>.
141       *
142       * @return The parent map (possibly <code>null</code>).
143       *
144       * @see #setParent(InputMap)
145       */
146      public InputMap getParent()
147      {
148        return parent;
149      }
150    
151      /**
152       * Sets a parent for this <code>InputMap</code>.  If a parent is specified,
153       * the {@link #get(KeyStroke)} method will look in the parent if it cannot
154       * find an entry in this map.
155       *
156       * @param parentMap the new parent (<code>null</code> permitted).
157       *
158       * @see #getParent()
159       */
160      public void setParent(InputMap parentMap)
161      {
162        parent = parentMap;
163      }
164    
165      /**
166       * Returns the number of entries in this <code>InputMap</code>.  This count
167       * does not include any entries from the parent map, if there is one.
168       *
169       * @return The number of entries.
170       */
171      public int size()
172      {
173        int result = 0;
174        if (inputMap != null)
175          result = inputMap.size();
176        return result;
177      }
178    
179      /**
180       * Clears the entries from this <code>InputMap</code>.  The parent map, if
181       * there is one, is not cleared.
182       */
183      public void clear()
184      {
185        if (inputMap != null)
186          inputMap.clear();
187      }
188    
189      /**
190       * Returns all keys of entries in this <code>InputMap</code>.  This does not
191       * include keys defined in the parent, if there is one (use the
192       * {@link #allKeys()} method for that case).
193       * <br><br>
194       * Following the behaviour of the reference implementation, this method will
195       * return <code>null</code> when no entries have been added to the map,
196       * and a zero length array if entries have been added but subsequently
197       * removed (or cleared) from the map.
198       *
199       * @return An array of keys (may be <code>null</code> or have zero length).
200       */
201      public KeyStroke[] keys()
202      {
203        if (inputMap != null)
204          {
205            KeyStroke[] array = new KeyStroke[size()];
206            return (KeyStroke[]) inputMap.keySet().toArray(array);
207          }
208        return null;
209      }
210    
211      /**
212       * Returns all keys of entries in this <code>InputMap</code> and all its
213       * parents.
214       *
215       * @return An array of keys (may be <code>null</code> or have zero length).
216       */
217      public KeyStroke[] allKeys()
218      {
219        Set set = new HashSet();
220    
221        if (parent != null)
222          {
223            Object[] parentKeys = parent.allKeys();
224            if (parentKeys != null)
225              set.addAll(Arrays.asList(parentKeys));
226          }
227        if (inputMap != null)
228          set.addAll(inputMap.keySet());
229        if (set.size() == 0)
230          return null;
231        KeyStroke[] array = new KeyStroke[set.size()];
232        return (KeyStroke[]) set.toArray(array);
233      }
234    
235    }