include/comphelper/flagguard.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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   9  * This file incorporates work covered by the following license notice:
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  14  *   ownership. The ASF licenses this file to you under the Apache
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  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_COMPHELPER_FLAGGUARD_HXX
  21 #define INCLUDED_COMPHELPER_FLAGGUARD_HXX
  22
  23 #include <comphelper/scopeguard.hxx>
  24 #include <utility>
  25
  26 namespace comphelper
  27 {
  28
  29     //= ValueRestorationGuard
  30
  31     // note: can't store the originalValue in a ValueRestorationGuard member,
  32     // because it will be used from base class dtor
  33     template <typename T> struct ValueRestorationGuard_Impl
  34     {
  35         T& rVal;
  36         T const originalValue;
  37         ValueRestorationGuard_Impl(T& i_valRef)
  38             : rVal(i_valRef), originalValue(i_valRef) {}
  39         void operator()()
  40         {
  41             rVal = originalValue;
  42         }
  43     };
  44
  45     template <typename T>
  46     class ValueRestorationGuard : public ScopeGuard<ValueRestorationGuard_Impl<T>>
  47     {
  48     public:
  49         ValueRestorationGuard(T& i_valRef)
  50             : ScopeGuard<ValueRestorationGuard_Impl<T>>(ValueRestorationGuard_Impl(i_valRef))
  51         {}
  52
  53         template <typename T1>
  54         ValueRestorationGuard(T& i_valRef, T1&& i_temporaryValue)
  55             : ScopeGuard<ValueRestorationGuard_Impl<T>>(ValueRestorationGuard_Impl(i_valRef))
  56         {
  57             i_valRef = std::forward<T1>(i_temporaryValue);
  58         }
  59     };
  60
  61     typedef ValueRestorationGuard<bool> FlagRestorationGuard;
  62
  63     //= FlagGuard
  64
  65     // Guarantees that the flag is true within the scope of the guard, and is set to false after
  66     // its destruction, regardless of initial flag value
  67     class FlagGuard : public FlagRestorationGuard
  68     {
  69     public:
  70         // Set flag to false before passing its reference to base class ctor, so that it would be
  71         // reset back to false in base class dtor
  72         explicit FlagGuard(bool& i_flagRef)
  73             : FlagRestorationGuard((i_flagRef = false), true)
  74         {
  75         }
  76     };
  77
  78
  79 } // namespace comphelper
  80
  81
  82 #endif // INCLUDED_COMPHELPER_FLAGGUARD_HXX
  83
  84 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */