/*******************************************************************************
* Copyright (c) 2005, 2015 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;
import org.eclipse.core.runtime.Status;
/**
* <p>
* An abstract class for detecting violations in a strict linear undo/redo
* model. Once a violation is detected, subclasses implement the specific
* behavior for indicating whether or not the undo/redo should proceed.
* </p>
*
* @since 3.1
*/
public abstract class LinearUndoViolationDetector implements IOperationApprover {
/**
* Create an instance of LinearUndoViolationDetector.
*/
public LinearUndoViolationDetector() {
super();
}
/**
* Return a status indicating whether a linear redo violation is allowable.
* A linear redo violation is defined as a request to redo a particular
* operation even if it is not the most recently added operation to the redo
* history.
*
* @param operation
* the operation for which a linear redo violation has been
* detected.
* @param context
* the undo context in which the linear redo violation exists
* @param history
* the operation history containing 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.
*
* @return the IStatus describing whether the redo violation is allowed. 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. Specific status
* severities will not be interpreted by the history.
*/
protected abstract IStatus allowLinearRedoViolation(
IUndoableOperation operation, IUndoContext context,
IOperationHistory history, IAdaptable info);
/**
* Return a status indicating whether a linear undo violation is allowable.
* A linear undo violation is defined as a request to undo a particular
* operation even if it is not the most recently added operation to the undo
* history.
*
* @param operation
* the operation for which a linear undo violation has been
* detected.
* @param context
* the undo context in which the linear undo violation exists
* @param history
* the operation history containing 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.
*
* @return the IStatus describing whether the undo violation is allowed. 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. Specific status
* severities will not be interpreted by the history.
*/
protected abstract IStatus allowLinearUndoViolation(
IUndoableOperation operation, IUndoContext context,
IOperationHistory history, IAdaptable info);
@Override
public final IStatus proceedRedoing(IUndoableOperation operation,
IOperationHistory history, IAdaptable info) {
IUndoContext[] contexts = operation.getContexts();
for (IUndoContext context : contexts) {
if (history.getRedoOperation(context) != operation) {
IStatus status = allowLinearRedoViolation(operation, context,
history, info);
if (!status.isOK()) {
return status;
}
}
}
return Status.OK_STATUS;
}
@Override
public final IStatus proceedUndoing(IUndoableOperation operation,
IOperationHistory history, IAdaptable info) {
IUndoContext[] contexts = operation.getContexts();
for (IUndoContext context : contexts) {
if (history.getUndoOperation(context) != operation) {
IStatus status = allowLinearUndoViolation(operation, context,
history, info);
if (!status.isOK()) {
return status;
}
}
}
return Status.OK_STATUS;
}
}