RefCountedPimpl.hpp

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#ifndef REF_COUNTED_PIMPL_HPP
#define REF_COUNTED_PIMPL_HPP


#include "blocxx/BLOCXX_config.h"
#include "blocxx/IntrusiveCountableBase.hpp"
#include "blocxx/IntrusiveReference.hpp"

namespace BLOCXX_NAMESPACE
{

   template <typename Impl>
   class RefCountedPimpl
   {
   protected:
      // These member functions will only get instantiated where they are
      // used -- in the implementation code for the class.  Thus the full
      // definition of Impl need not be visible in code that merely uses
      // a class derived from RefCountedPimpl<Impl>.
      // Unfortunately this is not the case for any classes which need
      // to be exported from a DLL (using __declspec(dllexport)) on
      // windows. If that is the case, then the definition does need
      // to be visible because every member function of the exported
      // class and it's base classes will be instantiated.

      // 
      RefCountedPimpl()
      : m_impl(0)
      {
      }

      //
      RefCountedPimpl(Impl * p)
      : m_impl(p)
      {
      }

      //
      RefCountedPimpl(IntrusiveCountableBase * p)
      : m_impl(p)
      {
      }

      //
      Impl * pimpl() const
      {
         return static_cast<Impl *>(m_impl.getPtr());
      }

      //
      bool null() const
      {
         return !m_impl;
      }

   private:
      // IntrusiveCountableBase is used instead of Impl because we want to
      // be able to hide the full definition of Impl while still having
      // the implicit copy ctor, copy assignment, and dtor available.
      //
      IntrusiveReference<IntrusiveCountableBase> m_impl;
   };

}

#endif