001/* InputMap.java --
002   Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.swing;
039
040import java.io.Serializable;
041import java.util.Arrays;
042import java.util.HashMap;
043import java.util.HashSet;
044import java.util.Map;
045import 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 */
061public 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}