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Java > Open Source Codes > org > eclipse > core > commands > operations > IAdvancedUndoableOperation2


1 /*******************************************************************************
2  * Copyright (c) 2006 IBM Corporation and others.
3  * All rights reserved. This program and the accompanying materials
4  * are made available under the terms of the Eclipse Public License v1.0
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/epl-v10.html
7  *
8  * Contributors:
9  * IBM Corporation - initial API and implementation
10  *******************************************************************************/
11 package org.eclipse.core.commands.operations;
12
13 import org.eclipse.core.commands.ExecutionException;
14 import org.eclipse.core.runtime.IProgressMonitor;
15 import org.eclipse.core.runtime.IStatus;
16
17 /**
18  * <p>
19  * IAdvancedUndoableOperation2 defines a method for computing the validity of
20  * executing an operation before attempting to execute it. It also defines a way
21  * for clients to specify that computing status should be done quietly, without
22  * consulting the user. This interface is useful when implementing
23  * {@link IOperationApprover2}, or any other object that performs validation of
24  * the undo history. It also allows operations to specify whether they should be
25  * run in the UI thread.
26  * </p>
27  *
28  * @since 3.3
29  *
30  */
31 public interface IAdvancedUndoableOperation2 {
32     /**
33      * Return a status indicating the projected outcome of executing the
34      * receiver.
35      *
36      * This method should be used to report the possible outcome of executing an
37      * operation when computing the validity of an execute is too expensive to
38      * perform in {@link IUndoableOperation#canExecute()}. It is not called by
39      * the operation history, but instead is used by clients (such as
40      * implementers of {@link IOperationApprover2}) who wish to perform
41      * advanced validation of an operation before attempting to execute it.
42      *
43      * If the result of this method is the discovery that an operation can in
44      * fact not be executed, then the operation is expected to correctly answer
45      * <code>false</code> on subsequent calls to
46      * {@link IUndoableOperation#canExecute()}.
47      *
48      * @param monitor
49      * the progress monitor (or <code>null</code>) to use for
50      * reporting progress to the user while computing the validity.
51      *
52      * @return the IStatus indicating the validity of the execute. The status
53      * severity should be set to <code>OK</code> if the execute can
54      * successfully be performed, and <code>ERROR</code> if it cannot.
55      * Any other severity is assumed to represent an ambiguous state.
56      * @throws ExecutionException
57      * if an exception occurs while computing the validity.
58      */
59     IStatus computeExecutionStatus(IProgressMonitor monitor)
60             throws ExecutionException;
61
62     /**
63      * Set a boolean that instructs whether the computation of the receiver's
64      * execution, undo, or redo status should quietly compute status without
65      * consulting or prompting the user. The default value is <code>false</code>.
66      * This flag should only be set to <code>true</code> while the execution,
67      * undo, or redo status computations are being performed in the background,
68      * and should be restored to <code>false</code> when complete.
69      * <p>
70      * If the status computation methods typically need to consult the user in
71      * order to determine the severity of a particular situation, the least
72      * severe status that could be chosen by the user should be returned when
73      * this flag is <code>true</code>. This can help to prevent overzealous
74      * disposal of the operation history when an operation is in an ambiguous
75      * state. Typically, the status computation methods are invoked with this
76      * flag set to <code>false</code> just before the actual execution, undo,
77      * or redo occurs, so the user can be consulted for the final outcome.
78      *
79      * @param quiet
80      * <code>true</code> if it is inappropriate to consult or
81      * otherwise prompt the user while computing status, and
82      * <code>false</code> if the user may be prompted.
83      *
84      * @see #computeExecutionStatus(IProgressMonitor)
85      * @see IAdvancedUndoableOperation#computeUndoableStatus(IProgressMonitor)
86      * @see IAdvancedUndoableOperation#computeRedoableStatus(IProgressMonitor)
87      */
88     public void setQuietCompute(boolean quiet);
89
90     /**
91      * Return a boolean that instructs whether the operation should be executed,
92      * undone, or redone in a background thread.
93      *
94      * @return <code>true</code> if the operation should be run in the
95      * background, <code>false</code> if it should not.
96      */
97     public boolean runInBackground();
98 }
99
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