gecko-dev/xpcom/glue/AutoRestore.h

78 lines
2.7 KiB
C++

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsAutoRestore.h.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/* functions for restoring saved values at the end of a C++ scope */
#ifndef mozilla_AutoRestore_h_
#define mozilla_AutoRestore_h_
#include "mozilla/GuardObjects.h"
namespace mozilla {
/**
* Save the current value of a variable and restore it when the object
* goes out of scope. For example:
* {
* AutoRestore<bool> savePainting(mIsPainting);
* mIsPainting = true;
*
* // ... your code here ...
*
* // mIsPainting is reset to its old value at the end of this block
* }
*/
template <class T>
class NS_STACK_CLASS AutoRestore
{
private:
T& mLocation;
T mValue;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
public:
AutoRestore(T& aValue MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
: mLocation(aValue), mValue(aValue)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
}
~AutoRestore() { mLocation = mValue; }
};
} // namespace mozilla
#endif /* !defined(mozilla_AutoRestore_h_) */