001/* StateEditable.java -- Interface for collaborating with StateEdit.
002   Copyright (C) 2002, 2003, 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.undo;
039
040import java.util.Hashtable;
041
042
043/**
044 * The interface for objects whose state can be undone or redone by a
045 * {@link StateEdit} action.
046 *
047 * <p>The following example shows how to write a class that implements
048 * this interface.
049 *
050 * <pre> class Foo
051 *   implements StateEditable
052 * {
053 *   private String name;
054 *
055 *   public void setName(String n) { name = n; }
056 *
057 *   public void restoreState(Hashtable h)
058 *   {
059 *     if (h.containsKey("name"))
060 *       setName((String) h.get("name"));
061 *   }
062 *
063 *   public void storeState(Hashtable s)
064 *   {
065 *     s.put("name", name);
066 *   }
067 * }</pre>
068 *
069 * @see StateEdit
070 *
071 * @author Andrew Selkirk (aselkirk@sympatico.ca)
072 * @author Sascha Brawer (brawer@dandelis.ch)
073 */
074public interface StateEditable
075{
076  /**
077   * The ID of the Java source file in Sun&#x2019;s Revision Control
078   * System (RCS).  This certainly should not be part of the API
079   * specification. But in order to be API-compatible with
080   * Sun&#x2019;s reference implementation, GNU Classpath also has to
081   * provide this field and match its value. The value used here has
082   * been in every JDK release at least from 1.2 to 1.5.
083   */
084  String RCSID = "$" +
085    "Id: StateEditable.java,v 1.2 1997/09/08 19:39:08 marklin Exp $";
086
087
088  /**
089   * Performs an edit action, taking any editable state information
090   * from the specified hash table.
091   *
092   * <p><b>Note to implementors of this interface:</b> To increase
093   * efficiency, the <code>StateEdit</code> class {@link
094   * StateEdit#removeRedundantState()} removes redundant state
095   * information. Therefore, implementations of this interface must be
096   * prepared for the case where certain keys were stored into the
097   * table by {@link #storeState}, but are not present anymore
098   * when the <code>restoreState</code> method gets called.
099   *
100   * @param state a hash table containing the relevant state
101   * information.
102   */
103  void restoreState(Hashtable<?, ?> state);
104
105
106  /**
107   * Stores any editable state information into the specified hash
108   * table.
109   *
110   * @param state a hash table for storing relevant state
111   * information.
112   */
113  void storeState(Hashtable<Object, Object> state);
114}