IUndoableEdit.java

/*******************************************************************************
 * Copyright (c) 2004, 2008 John Krasnay and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     John Krasnay - initial API and implementation
 *******************************************************************************/
package net.sf.vex.undo;

/**
 * Represents a change to a document (an edit) that can be undone and redone.
 * Typically, the edit source (i.e. the document) will have a flag that is set 
 * by the edit to indicate that the edits being performed are part of an undo
 * or redo. The document can use this to supress events to any 
 * IUndoableEventListeners during undo/redo. 
 */
public interface IUndoableEdit {

    /**
     * Try to combine the given edit event with this one. The common use-case
     * involves a user typing sequential characters into the document: all 
     * such insertions should be undone in one go.
     * 
     * @param edit IUndoableEdit to be combined with this one.
     * @return True if the given edit was successfully combined into this one.
     */
    public boolean combine(IUndoableEdit edit);
    
    /**
     * Redo the edit.
     */
    public void redo() throws CannotRedoException;

    /**
     * Undo the edit.
     */
    public void undo() throws CannotUndoException;
}