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/* * @(#)UndoableEditSupport.java 1.21 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.swing.undo; import javax.swing.event.*; import java.util.*; /** * A support class used for managing <code>UndoableEdit</code> listeners. * * @author Ray Ryan * @version 1.21 11/17/05 */ public class UndoableEditSupport { protected int updateLevel; protected CompoundEdit compoundEdit; protected Vector<UndoableEditListener> listeners; protected Object realSource; /** * Constructs an <code>UndoableEditSupport</code> object. */ public UndoableEditSupport() { this(null); } /** * Constructs an <code>UndoableEditSupport</code> object. * * @param r an <code>Object</code> */ public UndoableEditSupport(Object r) { realSource = r == null ? this : r; updateLevel = 0; compoundEdit = null; listeners = new Vector<UndoableEditListener>(); } /** * Registers an <code>UndoableEditListener</code>. * The listener is notified whenever an edit occurs which can be undone. * * @param l an <code>UndoableEditListener</code> object * @see #removeUndoableEditListener */ public synchronized void addUndoableEditListener(UndoableEditListener l) { listeners.addElement(l); } /** * Removes an <code>UndoableEditListener</code>. * * @param l the <code>UndoableEditListener</code> object to be removed * @see #addUndoableEditListener */ public synchronized void removeUndoableEditListener(UndoableEditListener l) { listeners.removeElement(l); } /** * Returns an array of all the <code>UndoableEditListener</code>s added * to this UndoableEditSupport with addUndoableEditListener(). * * @return all of the <code>UndoableEditListener</code>s added or an empty * array if no listeners have been added * @since 1.4 */ public synchronized UndoableEditListener[] getUndoableEditListeners() { return (UndoableEditListener[])(listeners.toArray( new UndoableEditListener[0])); } /** * Called only from <code>postEdit</code> and <code>endUpdate</code>. Calls * <code>undoableEditHappened</code> in all listeners. No synchronization * is performed here, since the two calling methods are synchronized. */ protected void _postEdit(UndoableEdit e) { UndoableEditEvent ev = new UndoableEditEvent(realSource, e); Enumeration cursor = ((Vector)listeners.clone()).elements(); while (cursor.hasMoreElements()) { ((UndoableEditListener)cursor.nextElement()). undoableEditHappened(ev); } } /** * DEADLOCK WARNING: Calling this method may call * <code>undoableEditHappened</code> in all listeners. * It is unwise to call this method from one of its listeners. */ public synchronized void postEdit(UndoableEdit e) { if (updateLevel == 0) { _postEdit(e); } else { // PENDING(rjrjr) Throw an exception if this fails? compoundEdit.addEdit(e); } } /** * Returns the update level value. * * @return an integer representing the update level */ public int getUpdateLevel() { return updateLevel; } /** * */ public synchronized void beginUpdate() { if (updateLevel == 0) { compoundEdit = createCompoundEdit(); } updateLevel++; } /** * Called only from <code>beginUpdate</code>. * Exposed here for subclasses' use. */ protected CompoundEdit createCompoundEdit() { return new CompoundEdit(); } /** * DEADLOCK WARNING: Calling this method may call * <code>undoableEditHappened</code> in all listeners. * It is unwise to call this method from one of its listeners. */ public synchronized void endUpdate() { updateLevel--; if (updateLevel == 0) { compoundEdit.end(); _postEdit(compoundEdit); compoundEdit = null; } } /** * Returns a string that displays and identifies this * object's properties. * * @return a <code>String</code> representation of this object */ public String toString() { return super.toString() + " updateLevel: " + updateLevel + " listeners: " + listeners + " compoundEdit: " + compoundEdit; } }