| /******************************************************************************* |
| * Copyright (c) 2005 IBM Corporation 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: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.core.commands.operations; |
| |
| /** |
| * <p> |
| * This class is used to maintain the instance of the operation history that |
| * should be used by classes that access the undo or redo history and add |
| * undoable operations to the history. |
| * |
| * <p> |
| * It is intended that an application can create an operation history appropriate |
| * for its needs and set it into this class. Otherwise, a default operation history |
| * will be created. The operation history may only be set one time. All classes that |
| * access an operations history use this class to obtain the correct instance. |
| * |
| * @since 3.1 |
| */ |
| public final class OperationHistoryFactory { |
| |
| private static IOperationHistory operationHistory; |
| |
| /** |
| * Return the operation history to be used for managing undoable operations. |
| * |
| * @return the operation history to be used for executing, undoing, and |
| * redoing operations. |
| */ |
| public static IOperationHistory getOperationHistory() { |
| if (operationHistory == null) { |
| operationHistory = new DefaultOperationHistory(); |
| } |
| return operationHistory; |
| } |
| |
| /** |
| * Set the operation history to be used for managing undoable operations. |
| * This method may only be called one time, and must be called before any |
| * request to get the history. Attempts to set the operation history will |
| * be ignored after it has been already set, or after a default one has |
| * been created. |
| * |
| * @param history |
| * the operation history to be used for executing, undoing, and |
| * redoing operations. |
| */ |
| public static void setOperationHistory(IOperationHistory history) { |
| // If one has already been set or created, ignore this request. |
| if (operationHistory == null) { |
| operationHistory = history; |
| } |
| } |
| |
| private OperationHistoryFactory() { |
| // may not be instantiated |
| } |
| |
| } |