1 : /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
2 : /* ***** BEGIN LICENSE BLOCK *****
3 : * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4 : *
5 : * The contents of this file are subject to the Mozilla Public License Version
6 : * 1.1 (the "License"); you may not use this file except in compliance with
7 : * the License. You may obtain a copy of the License at
8 : * http://www.mozilla.org/MPL/
9 : *
10 : * Software distributed under the License is distributed on an "AS IS" basis,
11 : * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12 : * for the specific language governing rights and limitations under the
13 : * License.
14 : *
15 : * The Original Code is nsAutoRestore.h.
16 : *
17 : * The Initial Developer of the Original Code is the Mozilla Foundation.
18 : * Portions created by the Initial Developer are Copyright (C) 2009
19 : * the Initial Developer. All Rights Reserved.
20 : *
21 : * Contributor(s):
22 : * L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
23 : *
24 : * Alternatively, the contents of this file may be used under the terms of
25 : * either the GNU General Public License Version 2 or later (the "GPL"), or
26 : * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
27 : * in which case the provisions of the GPL or the LGPL are applicable instead
28 : * of those above. If you wish to allow use of your version of this file only
29 : * under the terms of either the GPL or the LGPL, and not to allow others to
30 : * use your version of this file under the terms of the MPL, indicate your
31 : * decision by deleting the provisions above and replace them with the notice
32 : * and other provisions required by the GPL or the LGPL. If you do not delete
33 : * the provisions above, a recipient may use your version of this file under
34 : * the terms of any one of the MPL, the GPL or the LGPL.
35 : *
36 : * ***** END LICENSE BLOCK ***** */
37 :
38 : /* functions for restoring saved values at the end of a C++ scope */
39 :
40 : #ifndef mozilla_AutoRestore_h_
41 : #define mozilla_AutoRestore_h_
42 :
43 : #include "mozilla/GuardObjects.h"
44 :
45 : namespace mozilla {
46 :
47 : /**
48 : * Save the current value of a variable and restore it when the object
49 : * goes out of scope. For example:
50 : * {
51 : * AutoRestore<bool> savePainting(mIsPainting);
52 : * mIsPainting = true;
53 : *
54 : * // ... your code here ...
55 : *
56 : * // mIsPainting is reset to its old value at the end of this block
57 : * }
58 : */
59 : template <class T>
60 : class NS_STACK_CLASS AutoRestore
61 : {
62 : private:
63 : T& mLocation;
64 : T mValue;
65 : MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
66 : public:
67 235 : AutoRestore(T& aValue MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
68 235 : : mLocation(aValue), mValue(aValue)
69 : {
70 235 : MOZ_GUARD_OBJECT_NOTIFIER_INIT;
71 235 : }
72 235 : ~AutoRestore() { mLocation = mValue; }
73 : };
74 :
75 : } // namespace mozilla
76 :
77 : #endif /* !defined(mozilla_AutoRestore_h_) */
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