/**
* Perform the undo. All validity checks have already occurred.
*
* @param monitor
* @param operation
*/
private IStatus doUndo(IProgressMonitor monitor, IAdaptable info, IUndoableOperation operation)
throws ExecutionException {
IStatus status = getUndoApproval(operation, info);
if (status.isOK()) {
notifyAboutToUndo(operation);
try {
status = operation.undo(monitor, info);
} catch (OperationCanceledException e) {
status = Status.CANCEL_STATUS;
} catch (ExecutionException e) {
notifyNotOK(operation);
if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
Tracing.printTrace(
"OPERATIONHISTORY", //$NON-NLS-1$
"ExecutionException while undoing " + operation); // $NON-NLS-1$
}
throw e;
} catch (Exception e) {
notifyNotOK(operation);
if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
Tracing.printTrace(
"OPERATIONHISTORY", //$NON-NLS-1$
"Exception while undoing " + operation); // $NON-NLS-1$
}
throw new ExecutionException(
"While undoing the operation, an exception occurred", e); // $NON-NLS-1$
}
}
// if successful, the operation is removed from the undo history and
// placed in the redo history.
if (status.isOK()) {
boolean addedToRedo = true;
synchronized (undoRedoHistoryLock) {
undoList.remove(operation);
if (checkRedoLimit(operation)) {
redoList.add(operation);
} else {
addedToRedo = false;
}
}
// dispose the operation since we could not add it to the
// stack and will no longer have a reference to it.
if (!addedToRedo) {
operation.dispose();
}
// notification occurs after the undo and redo histories are
// adjusted
notifyUndone(operation);
} else {
notifyNotOK(operation, status);
}
return status;
}