/* StateEdit.java --
   Copyright (C) 2002, 2003 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
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing.undo;

import java.util.Hashtable;
import java.util.Iterator;

/**
 * StateEdit
 * @author	Andrew Selkirk
 */
public class StateEdit extends AbstractUndoableEdit
{

  //-------------------------------------------------------------
  // Variables --------------------------------------------------
  //-------------------------------------------------------------

  /**
   * RCSID
   */
  protected static final String RCSID = ""; // TODO

  /**
   * object
   */
  protected StateEditable object;

  /**
   * preState
   */
  protected Hashtable preState;

  /**
   * postState
   */
  protected Hashtable postState;

  /**
   * undoRedoName
   */
  protected String undoRedoName;


  //-------------------------------------------------------------
  // Initialization ---------------------------------------------
  //-------------------------------------------------------------

  /**
   * Constructor StateEdit
   * @param obj Object to edit
   */
  public StateEdit(StateEditable obj)
  {
    init(obj, null);
  }

  /**
   * Constructor StateEdit
   * @param obj Object to edit
   * @param name Presentation name
   */
  public StateEdit(StateEditable obj, String name)
  {
    init(obj, name);
  }


  //-------------------------------------------------------------
  // Methods ----------------------------------------------------
  //-------------------------------------------------------------

  /**
   * Initialize this object.
   * @param obj Object to edit
   * @param name Presentation name
   */
  protected void init(StateEditable obj, String name)
  {
    object = obj;
    undoRedoName = name;
    preState = new Hashtable();
    postState = new Hashtable();
    obj.storeState(preState);
  }

  /**
   * Indicate that all edits are finished, and update this object
   * with final state.
   */
  public void end()
  {
    object.storeState(postState);
    removeRedundantState();
  }

  /**
   * Undo this edit by applying the initial state to the edited object.
   */
  public void undo()
  {
    object.restoreState(preState);
  }

  /**
   * Undo this edit by applying the final state to the edited object.
   */
  public void redo()
  {
    object.restoreState(postState);
  }

  /**
   * Return the presentation name of this object.
   * @returns The name, or null if not set
   */
  public String getPresentationName()
  {
    return undoRedoName;
  }

  /**
   * removeRedundantState
   */
  protected void removeRedundantState()
  {
    Iterator i = preState.keySet().iterator();
    while (i.hasNext())
      {
	Object key = i.next();
	if (postState.containsKey(key))
	  {
	    if (preState.get(key).equals(postState.get(key)))
	      {
		i.remove();
		postState.remove(key);
	      }
	  }
      }
  }
}