--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/core/commands/operations/IAdvancedUndoableOperation.d	Wed Mar 26 00:57:19 2008 +0100
@@ -0,0 +1,133 @@
+/*******************************************************************************
+ * 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
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+module dwtx.core.commands.operations.IAdvancedUndoableOperation;
+
+import dwtx.core.commands.ExecutionException;
+import dwtx.core.runtime.IProgressMonitor;
+import dwtx.core.runtime.IStatus;
+
+import dwtx.core.commands.operations.OperationHistoryEvent;
+
+import dwt.dwthelper.utils;
+
+/**
+ * <p>
+ * IAdvancedUndoableOperation defines an interface for undoable operations that
+ * modify one or more elements in a model and attempt to keep model listeners up
+ * to date with changes that occur in the undo and redo history involving particular
+ * model elements.  It also defines methods for computing the validity of an operation
+ * for undo or redo before attempting to perform the undo or redo.
+ * </p>
+ * <p>
+ * This interface is intended to be used by legacy frameworks that are adapting
+ * their original undo and redo support to this framework. The methods in this
+ * interface allow legacy clients to maintain features not supported in the
+ * basic operations framework.
+ * </p>
+ *
+ * @since 3.1
+ *
+ */
+public interface IAdvancedUndoableOperation {
+
+    /**
+     * <p>
+     * An operation history notification about this operation is about to be
+     * sent to operation history listeners. Any preparation needed before
+     * listeners are notified about this operation should be performed here.
+     *
+     * <p>
+     * This method has been added to support legacy undo frameworks that are
+     * adapting to IUndoableOperation. Operations that previously relied on
+     * notification from their containing history or stack before any listeners
+     * are notified about changes to the operation should implement this
+     * interface.
+     *
+     * @param event
+     *            the event that is about to be sent with the pending
+     *            notification
+     *
+     */
+    void aboutToNotify(OperationHistoryEvent event);
+
+    /**
+     * <p>
+     * Return an array of objects that are affected by executing, undoing, or
+     * redoing this operation. If it cannot be determined which objects are
+     * affected, return null.
+     * </p>
+     *
+     * @return the array of Objects modified by this operation, or
+     *         <code>null</code> if the affected objects cannot be determined.
+     */
+    Object[] getAffectedObjects();
+
+    /**
+     * Return a status indicating the projected outcome of undoing the receiver.
+     *
+     * This method should be used to report the possible outcome of an undo and
+     * is used when computing the validity of an undo is too expensive to
+     * perform in {@link IUndoableOperation#canUndo()}. It is not called by the
+     * operation history, but instead is used by clients (such as implementers
+     * of {@link IOperationApprover}) who wish to perform advanced validation of
+     * an operation before attempting to undo it.
+     *
+     * If the result of this method is the discovery that an operation can in
+     * fact not be undone, then the operation is expected to correctly answer
+     * <code>false</code> on subsequent calls to
+     * {@link IUndoableOperation#canUndo()}.
+     *
+     * @param monitor
+     *            the progress monitor (or <code>null</code>) to use for
+     *            reporting progress to the user while computing the validity.
+     *
+     * @return the IStatus indicating the validity of the undo. The status
+     *         severity should be set to <code>OK</code> if the undo can
+     *         successfully be performed, and <code>ERROR</code> if it
+     *         cannnot. Any other status is assumed to represent an ambiguous
+     *         state.
+     * @throws ExecutionException
+     *             if an exception occurs while computing the validity.
+     */
+    IStatus computeUndoableStatus(IProgressMonitor monitor);
+
+    /**
+     * Return a status indicating the projected outcome of redoing the receiver.
+     *
+     * This method should be used to report the possible outcome of a redo and
+     * is used when computing the validity of a redo is too expensive to perform
+     * in {@link IUndoableOperation#canRedo()}. It is not called by the
+     * operation history, but instead is used by clients (such as implementers
+     * of {@link IOperationApprover}) who wish to perform advanced validation of
+     * an operation before attempting to redo it.
+     *
+     * If the result of this method is the discovery that an operation can in
+     * fact not be redone, then the operation is expected to correctly answer
+     * <code>false</code> on subsequent calls to
+     * {@link IUndoableOperation#canRedo()}.
+     *
+     * @param monitor
+     *            the progress monitor (or <code>null</code>) to use for
+     *            reporting progress to the user while computing the validity.
+     *
+     * @return the IStatus indicating the validity of the redo. The status
+     *         severity should be set to <code>OK</code> if the redo can
+     *         successfully be performed, and <code>ERROR</code> if it
+     *         cannnot. Any other status is assumed to represent an ambiguous
+     *         state.
+     * @throws ExecutionException
+     *             if an exception occurs while computing the validity.
+     */
+    IStatus computeRedoableStatus(IProgressMonitor monitor);
+
+}