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UndoableEdit.java
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1998-02-26
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/*
* @(#)UndoableEdit.java 1.10 98/02/05
*
* Copyright (c) 1997 Sun Microsystems, Inc. All Rights Reserved.
*
* This software is the confidential and proprietary information of Sun
* Microsystems, Inc. ("Confidential Information"). You shall not
* disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into
* with Sun.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
* SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
* SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
* THIS SOFTWARE OR ITS DERIVATIVES.
*
*/
package com.sun.java.swing.undo;
import com.sun.java.swing.event.*;
/**
* An object representing an edit that has been done, and that can be
* undone and redone
*
* @version 1.10, 02/05/98
* @author Ray Ryan
*/
public interface UndoableEdit {
/**
* Undo the edit that was made.
*/
public void undo() throws CannotUndoException;
/**
* True if it is still possible to undo this operation
*/
public boolean canUndo();
/**
* Re-apply the edit, assuming that it has been undone.
*/
public void redo() throws CannotRedoException;
/**
* True if it is still possible to redo this operation
*/
public boolean canRedo();
/**
* May be sent to inform an edit that it should no longer be
* used. This is a useful hook for cleaning up state no longer
* needed once undoing or redoing is impossible--for example,
* deleting file resources used by objects that can no longer be
* undeleted. UndoManager calls this before it dequeues edits.
*
* Note that this is a one-way operation. There is no "undie"
* method.
*
* @see CompoundEdit#die
*/
public void die();
/**
* This UndoableEdit should absorb anEdit if it can. Return true
* if anEdit has been incoporated, false if it has not.
*
* <p>Typically the receiver is already in the queue of a
* UndoManager (or other UndoableEditListener), and is being
* given a chance to incorporate anEdit rather than letting it be
* added to the queue in turn.</p>
*
* <p>If true is returned, from now on anEdit must return false from
* canUndo() and canRedo(), and must throw the appropriate
* exception on undo() or redo().</p>
*/
public boolean addEdit(UndoableEdit anEdit);
/**
* Return true if this UndoableEdit should replace anEdit. The
* receiver should incorporate anEdit's state before returning true.
*
* <p>This message is the opposite of addEdit--anEdit has typically
* already been queued in a UndoManager (or other
* UndoableEditListener), and the receiver is being given a chance
* to take its place.</p>
*
* <p>If true is returned, from now on anEdit must return false from
* canUndo() and canRedo(), and must throw the appropriate
* exception on undo() or redo().</p>
*/
public boolean replaceEdit(UndoableEdit anEdit);
/**
* Return false if this edit is insignificant--for example one
* that maintains the user's selection, but does not change any
* model state. This status can be used by an UndoableEditListener
* (like UndoManager) when deciding which UndoableEdits to present
* to the user as Undo/Redo options, and which to perform as side
* effects of undoing or redoing other events.
*/
public boolean isSignificant();
/**
* Provide a localized, human readable description of this edit
* suitable for use in, say, a change log.
*/
public String getPresentationName();
/**
* Provide a localized, human readable description of the undoable
* form of this edit, e.g. for use as an Undo menu item. Typically
* derived from getDescription();
*/
public String getUndoPresentationName();
/**
* Provide a localized, human readable description of the redoable
* form of this edit, e.g. for use as a Redo menu item. Typically
* derived from getPresentationName();
*/
public String getRedoPresentationName();
}