flagguard.hxx

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#ifndef INCLUDED_COMPHELPER_FLAGGUARD_HXX
#define INCLUDED_COMPHELPER_FLAGGUARD_HXX
 
#include <comphelper/scopeguard.hxx>
#include <utility>
 
namespace comphelper
{
 
    //= ValueRestorationGuard
 
    // note: can't store the originalValue in a ValueRestorationGuard member,
    // because it will be used from base class dtor
    template <typename T> struct ValueRestorationGuard_Impl
    {
        T& rVal;
        T const originalValue;
        ValueRestorationGuard_Impl(T& i_valRef)
            : rVal(i_valRef), originalValue(i_valRef) {}
        void operator()()
        {
            rVal = originalValue;
        }
    };
 
    template <typename T>
    class ValueRestorationGuard : public ScopeGuard<ValueRestorationGuard_Impl<T>>
    {
    public:
        ValueRestorationGuard(T& i_valRef)
            : ScopeGuard<ValueRestorationGuard_Impl<T>>(ValueRestorationGuard_Impl(i_valRef))
        {}
 
        template <typename T1>
        ValueRestorationGuard(T& i_valRef, T1&& i_temporaryValue)
            : ScopeGuard<ValueRestorationGuard_Impl<T>>(ValueRestorationGuard_Impl(i_valRef))
        {
            i_valRef = std::forward<T1>(i_temporaryValue);
        }
    };
 
    typedef ValueRestorationGuard<bool> FlagRestorationGuard;
 
    //= FlagGuard
 
    // Guarantees that the flag is true within the scope of the guard, and is set to false after
    // its destruction, regardless of initial flag value
    class FlagGuard : public FlagRestorationGuard
    {
    public:
        // Set flag to false before passing its reference to base class ctor, so that it would be
        // reset back to false in base class dtor
        explicit FlagGuard(bool& i_flagRef)
            : FlagRestorationGuard((i_flagRef = false), true)
        {
        }
    };
 
 
} // namespace comphelper
 
 
#endif // INCLUDED_COMPHELPER_FLAGGUARD_HXX
 
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