InputMap.java

/* InputMap.java --
   Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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package javax.swing;

import java.io.Serializable;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * Maps {@link KeyStroke}s to arbitrary objects, usually Strings. This
 * is used in combination with {@link ActionMap}s.
 *
 * If a component receives an input event, this is looked up in
 * the component's <code>InputMap</code>. The result is an object which
 * serves as a key to the component's <code>ActionMap</code>. Finally
 * the <code>Action</code> that is stored is executed.
 *
 * @author Andrew Selkirk
 * @author Michael Koch
 *
 * @since 1.3
 */
public class InputMap
  implements Serializable
{
  private static final long serialVersionUID = -5429059542008604257L;

  /**
   * Storage for the KeyStroke --> Object mappings.
   */
  private Map inputMap;

  /**
   * An optional parent map.
   */
  private InputMap parent;

  /**
   * Creates a new <code>InputMap</code> instance.  This default instance
   * contains no mappings and has no parent.
   */
  public InputMap()
  {
    // nothing to do
  }

  /**
   * Returns the binding for the specified keystroke, if there is one.
   *
   * @param keystroke the key of the entry (<code>null</code> is ignored).
   *
   * @return The binding associated with the specified keystroke (or 
   *     <code>null</code>).
   */
  public Object get(KeyStroke keystroke)
  {
    Object result = null;
    if (inputMap != null)
      result = inputMap.get(keystroke);

    if (result == null && parent != null)
      result = parent.get(keystroke);
    return result;
  }

  /**
   * Puts a new entry into the <code>InputMap</code>.  If 
   * <code>actionMapKey</code> is <code>null</code> any existing entry will be 
   * removed.
   *
   * @param keystroke the keystroke for the entry (<code>null</code> is 
   *     ignored).
   * @param actionMapKey the action (<code>null</code> permitted).
   */
  public void put(KeyStroke keystroke, Object actionMapKey)
  {
    if (keystroke == null)
      return;
    if (inputMap == null)
      inputMap = new HashMap();
    if (actionMapKey == null)
      inputMap.remove(keystroke);
    else
      inputMap.put(keystroke, actionMapKey);
  }

  /**
   * Removes an entry from this <code>InputMap</code>.  Note that this will
   * not remove any entry from the parent map, if there is one.
   *
   * @param keystroke the key of the entry to remove (<code>null</code> is 
   *     ignored).
   */
  public void remove(KeyStroke keystroke)
  {
    if (inputMap != null)
      inputMap.remove(keystroke);
  }

  /**
   * Returns the parent of this <code>InputMap</code>.  The default value
   * is <code>null</code>.
   *
   * @return The parent map (possibly <code>null</code>).
   * 
   * @see #setParent(InputMap)
   */
  public InputMap getParent()
  {
    return parent;
  }

  /**
   * Sets a parent for this <code>InputMap</code>.  If a parent is specified,
   * the {@link #get(KeyStroke)} method will look in the parent if it cannot
   * find an entry in this map.
   *
   * @param parentMap the new parent (<code>null</code> permitted).
   * 
   * @see #getParent()
   */
  public void setParent(InputMap parentMap)
  {
    parent = parentMap;
  }

  /**
   * Returns the number of entries in this <code>InputMap</code>.  This count 
   * does not include any entries from the parent map, if there is one.
   *
   * @return The number of entries.
   */
  public int size()
  {
    int result = 0;
    if (inputMap != null)
      result = inputMap.size();
    return result;
  }

  /**
   * Clears the entries from this <code>InputMap</code>.  The parent map, if
   * there is one, is not cleared.
   */
  public void clear()
  {
    if (inputMap != null)
      inputMap.clear();
  }

  /**
   * Returns all keys of entries in this <code>InputMap</code>.  This does not
   * include keys defined in the parent, if there is one (use the 
   * {@link #allKeys()} method for that case).
   * <br><br>
   * Following the behaviour of the reference implementation, this method will
   * return <code>null</code> when no entries have been added to the map, 
   * and a zero length array if entries have been added but subsequently 
   * removed (or cleared) from the map.
   *
   * @return An array of keys (may be <code>null</code> or have zero length).
   */
  public KeyStroke[] keys()
  {
    if (inputMap != null)
      {
        KeyStroke[] array = new KeyStroke[size()];
        return (KeyStroke[]) inputMap.keySet().toArray(array);
      }
    return null;
  }

  /**
   * Returns all keys of entries in this <code>InputMap</code> and all its 
   * parents.
   *
   * @return An array of keys (may be <code>null</code> or have zero length).
   */
  public KeyStroke[] allKeys()
  {
    Set set = new HashSet();

    if (parent != null)
      {
        Object[] parentKeys = parent.allKeys();
        if (parentKeys != null)
          set.addAll(Arrays.asList(parentKeys));
      }
    if (inputMap != null)
      set.addAll(inputMap.keySet());
    if (set.size() == 0)
      return null;    
    KeyStroke[] array = new KeyStroke[set.size()];
    return (KeyStroke[]) set.toArray(array);
  }

}