bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/operations/LinearUndoViolationUserApprover.java

/*******************************************************************************
 * Copyright (c) 2005, 2006 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.ui.operations;

import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.commands.operations.IOperationHistory;
import org.eclipse.core.commands.operations.IUndoContext;
import org.eclipse.core.commands.operations.IUndoableOperation;
import org.eclipse.core.commands.operations.LinearUndoViolationDetector;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.osgi.util.NLS;
import org.eclipse.ui.IWorkbenchPart;
import org.eclipse.ui.IWorkbenchPart2;
import org.eclipse.ui.internal.Workbench;
import org.eclipse.ui.internal.WorkbenchMessages;

/**
 * <p>
 * An operation approver that prompts the user to see if linear undo violations
 * are permitted. A linear undo violation is detected when an operation being
 * undone or redone shares an undo context with another operation appearing more
 * recently in the history.
 * </p>
 * <p>
 * This class may be instantiated by clients.
 * </p>
 * 
 * @since 3.1
 */
public final class LinearUndoViolationUserApprover extends
		LinearUndoViolationDetector {

	private IWorkbenchPart part;

	private IUndoContext context;

	/**
	 * Create a LinearUndoViolationUserApprover associated with the specified
	 * workbench part.
	 * 
	 * @param context
	 *            the undo context with the linear undo violation
	 * @param part
	 *            the part that should be used for prompting the user
	 */
	public LinearUndoViolationUserApprover(IUndoContext context,
			IWorkbenchPart part) {
		super();
		this.part = part;
		this.context = context;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.LinearUndoViolationDetector#allowLinearRedoViolation(org.eclipse.core.commands.operations.IUndoableOperation,
	 *      org.eclipse.core.commands.operations.IUndoContext,
	 *      org.eclipse.core.commands.operations.IOperationHistory,
	 *      org.eclipse.core.runtime.IAdaptable)
	 */
	protected IStatus allowLinearRedoViolation(IUndoableOperation operation,
			IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {

		if (this.context != context) {
			return Status.OK_STATUS;
		}

		final String message = NLS.bind(
				WorkbenchMessages.Operations_linearRedoViolation,
				getTitle(part), operation.getLabel());
		final boolean [] proceed = new boolean[1];
		Workbench.getInstance().getDisplay().syncExec(new Runnable() {
			public void run() {
				// Show a dialog.
				part.setFocus();
				proceed[0] = MessageDialog.openQuestion(part.getSite()
						.getShell(), getTitle(part), message);
			}
		});

		if (proceed[0]) {
			// redo the local changes first
			while (operation != history.getRedoOperation(context)) {
				try {
					IStatus status = history.redo(context, null, uiInfo);
					if (!status.isOK()) {
						// flush the redo history because the operation
						// failed
						history.dispose(context, false, true, false);
						return Status.CANCEL_STATUS;
					}
				} catch (ExecutionException e) {
					// flush the redo history here because it failed.
					history.dispose(context, false, true, false);
					return Status.CANCEL_STATUS;
				}
			}
			return Status.OK_STATUS;
		}

		return Status.CANCEL_STATUS;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.LinearUndoViolationDetector#allowLinearUndoViolation(org.eclipse.core.commands.operations.IUndoableOperation,
	 *      org.eclipse.core.commands.operations.IUndoContext,
	 *      org.eclipse.core.commands.operations.IOperationHistory,
	 *      org.eclipse.core.runtime.IAdaptable)
	 */
	protected IStatus allowLinearUndoViolation(IUndoableOperation operation,
			IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {

		if (this.context != context) {
			return Status.OK_STATUS;
		}

		final String message = NLS.bind(
				WorkbenchMessages.Operations_linearUndoViolation,
				getTitle(part), operation.getLabel());
		final boolean [] proceed = new boolean[1];
		Workbench.getInstance().getDisplay().syncExec(new Runnable() {
			public void run() {
				// Show a dialog.
				part.setFocus();
				proceed[0] = MessageDialog.openQuestion(part.getSite()
						.getShell(), getTitle(part), message);
			}
		});

		if (proceed[0]) {
			// redo the local changes first
			while (operation != history.getUndoOperation(context)) {
				try {
					IStatus status = history.undo(context, null, uiInfo);
					if (!status.isOK()) {
						// flush the operation history because the operation
						// failed.
						history.dispose(context, true, false, false);
						return Status.CANCEL_STATUS;
					}
				} catch (ExecutionException e) {
					// flush the undo history here because something went wrong.
					history.dispose(context, true, false, false);
					return Status.CANCEL_STATUS;
				}
			}
			return Status.OK_STATUS;
		}
		return Status.CANCEL_STATUS;
	}

	/*
	 * Get the title for the specified part. Use the newer interface
	 * IWorkbenchPart2 if available.
	 */
	private String getTitle(IWorkbenchPart part) {
		String title;
		if (part instanceof IWorkbenchPart2) {
			title = ((IWorkbenchPart2) part).getPartName();
		} else {
			title = part.getTitle();
		}
		// Null title is unexpected, but use an empty string if encountered.
		if (title == null) {
			title = ""; //$NON-NLS-1$
		}
		return title;
	}
}