xpcom/glue/nsIInterfaceRequestorUtils.h

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  38
  39 #ifndef __nsInterfaceRequestorUtils_h
  40 #define __nsInterfaceRequestorUtils_h
  41
  42 #include "nsCOMPtr.h"
  43
  44 // a type-safe shortcut for calling the |GetInterface()| member function
  45 // T must inherit from nsIInterfaceRequestor, but the cast may be ambiguous.
  46 template <class T, class DestinationType>
  47 inline
  48 nsresult
  49 CallGetInterface( T* aSource, DestinationType** aDestination )
  50   {
  51     NS_PRECONDITION(aSource, "null parameter");
  52     NS_PRECONDITION(aDestination, "null parameter");
  53
  54     return aSource->GetInterface(NS_GET_TEMPLATE_IID(DestinationType),
  55                                  reinterpret_cast<void**>(aDestination));
  56   }
  57
  58 class NS_COM_GLUE nsGetInterface : public nsCOMPtr_helper
  59   {
  60     public:
  61       nsGetInterface( nsISupports* aSource, nsresult* error )
  62           : mSource(aSource),
  63             mErrorPtr(error)
  64         {
  65           // nothing else to do here
  66         }
  67
  68       virtual nsresult NS_FASTCALL operator()( const nsIID&, void** ) const;
  69
  70     private:
  71       nsISupports*          mSource;
  72       nsresult*             mErrorPtr;
  73   };
  74
  75 inline
  76 const nsGetInterface
  77 do_GetInterface( nsISupports* aSource, nsresult* error = 0 )
  78   {
  79     return nsGetInterface(aSource, error);
  80   }
  81
  82 #endif // __nsInterfaceRequestorUtils_h
  83