| /******************************************************************************* |
| * 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; |
| |
| import org.eclipse.core.runtime.IAdaptable; |
| import org.eclipse.core.runtime.IStatus; |
| |
| /** |
| * <p> |
| * IOperationApprover defines an interface for approving the undo or redo of a |
| * particular operation within an operation history. Operations that are |
| * candidates for undo or redo have already been validated against their current |
| * state and according to the rules of the history. |
| * </p> |
| * <p> |
| * By the time an IOperationApprover is consulted, the undo has already been |
| * requested. Approvers should return an <code>IStatus</code> object with |
| * severity <code>OK</code> if the operation should proceed, and any other |
| * severity if it should not. When an operation is not approved, it is expected |
| * that the object not allowing the operation has already consulted the user if |
| * necessary or otherwise provided any necessary information to the user about |
| * the fact that the operation is not approved. |
| * </p> |
| * <p> |
| * Operation approvers must be prepared to receive the approval messages from a |
| * background thread. Any UI access occurring inside the implementation must be |
| * properly synchronized using the techniques specified by the client's widget |
| * library. |
| * </p> |
| * |
| * @since 3.1 |
| */ |
| public interface IOperationApprover { |
| |
| /** |
| * Return a status indicating whether the specified operation should be |
| * redone. Any status that does not have severity <code>IStatus.OK</code> |
| * will not be approved. Implementers should not assume that the redo will |
| * be performed when the status is <code>OK</code>, since other operation |
| * approvers may veto the redo. |
| * |
| * @param operation |
| * the operation to be redone |
| * @param history |
| * the history redoing the operation |
| * @param info |
| * the IAdaptable (or <code>null</code>) provided by the |
| * caller in order to supply UI information for prompting the |
| * user if necessary. When this parameter is not |
| * <code>null</code>, it should minimally contain an adapter |
| * for the org.eclipse.swt.widgets.Shell.class. Even if UI |
| * information is provided, the implementation of this method |
| * must be prepared for being called from a background thread. |
| * Any UI access must be properly synchronized using the |
| * techniques specified by the client's widget library. |
| * @return the IStatus describing whether the operation is approved. The |
| * redo will not proceed if the status severity is not |
| * <code>OK</code>, and the caller requesting the redo will be |
| * returned the status that caused the rejection. Any other status |
| * severities will not be interpreted by the history. |
| */ |
| IStatus proceedRedoing(IUndoableOperation operation, |
| IOperationHistory history, IAdaptable info); |
| |
| /** |
| * Return a status indicating whether the specified operation should be |
| * undone. Any status that does not have severity <code>IStatus.OK</code> |
| * will not be approved. Implementers should not assume that the undo will |
| * be performed when the status is <code>OK</code>, since other operation |
| * approvers can veto the undo. |
| * |
| * @param operation |
| * the operation to be undone |
| * @param history |
| * the history undoing the operation |
| * @param info |
| * the IAdaptable (or <code>null</code>) provided by the |
| * caller in order to supply UI information for prompting the |
| * user if necessary. When this parameter is not |
| * <code>null</code>, it should minimally contain an adapter |
| * for the org.eclipse.swt.widgets.Shell.class. Even if UI |
| * information is provided, the implementation of this method |
| * must be prepared for being called from a background thread. |
| * Any UI access must be properly synchronized using the |
| * techniques specified by the client's widget library. |
| * @return the IStatus describing whether the operation is approved. The |
| * undo will not proceed if the status severity is not |
| * <code>OK</code>, and the caller requesting the undo will be |
| * returned the status that caused the rejection. Any other status |
| * severities will not be interpreted by the history. |
| */ |
| IStatus proceedUndoing(IUndoableOperation operation, |
| IOperationHistory history, IAdaptable info); |
| |
| } |
