michael@0: /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* functions for restoring saved values at the end of a C++ scope */
michael@0: 
michael@0: #ifndef mozilla_AutoRestore_h_
michael@0: #define mozilla_AutoRestore_h_
michael@0: 
michael@0: #include "mozilla/Attributes.h" // MOZ_STACK_CLASS
michael@0: #include "mozilla/GuardObjects.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0:   /**
michael@0:    * Save the current value of a variable and restore it when the object
michael@0:    * goes out of scope.  For example:
michael@0:    *   {
michael@0:    *     AutoRestore<bool> savePainting(mIsPainting);
michael@0:    *     mIsPainting = true;
michael@0:    *     
michael@0:    *     // ... your code here ...
michael@0:    *
michael@0:    *     // mIsPainting is reset to its old value at the end of this block
michael@0:    *   }
michael@0:    */
michael@0:   template <class T>
michael@0:   class MOZ_STACK_CLASS AutoRestore
michael@0:   {
michael@0:   private:
michael@0:     T& mLocation;
michael@0:     T mValue;
michael@0:     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
michael@0:   public:
michael@0:     AutoRestore(T& aValue MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
michael@0:       : mLocation(aValue), mValue(aValue)
michael@0:     {
michael@0:       MOZ_GUARD_OBJECT_NOTIFIER_INIT;
michael@0:     }
michael@0:     ~AutoRestore() { mLocation = mValue; }
michael@0:   };
michael@0: 
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif /* !defined(mozilla_AutoRestore_h_) */