SafeBool.h

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#ifndef ZYPP_BASE_SAFEBOOL_H
#define ZYPP_BASE_SAFEBOOL_H

namespace zypp
{ 

  namespace base
  { 

    namespace safebool_detail
    {
      class SafeBoolBase
      {
      protected:
        typedef void (SafeBoolBase::*bool_type)() const;
        void theTrueBoolType() const {}

        SafeBoolBase() {}
        SafeBoolBase( const SafeBoolBase & ) {}
        ~SafeBoolBase() {}
        SafeBoolBase & operator=( const SafeBoolBase & ) { return *this; }
      };
    }

    //
    //  CLASS NAME : SafeBool
    //
    template<class _Derived>
      struct SafeBool : private safebool_detail::SafeBoolBase
      {
        using safebool_detail::SafeBoolBase::bool_type;
        operator bool_type() const
        {
          return( (static_cast<const _Derived *>(this))->boolTest()
                  ? &safebool_detail::SafeBoolBase::theTrueBoolType
                  : 0 );
        }
      protected:
        ~SafeBool() {}
      };

  } // namespace base
} // namespace zypp
#endif // ZYPP_BASE_SAFEBOOL_H