/gecko_api/include/nsIWeakReferenceUtils.h

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 38
 39#ifndef nsIWeakReferenceUtils_h__
 40#define nsIWeakReferenceUtils_h__
 41
 42#ifndef nsCOMPtr_h__
 43#include "nsCOMPtr.h"
 44#endif
 45
 46typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
 47
 48/**
 49 *
 50 */
 51
 52// a type-safe shortcut for calling the |QueryReferent()| member function
 53// T must inherit from nsIWeakReference, but the cast may be ambiguous.
 54template <class T, class DestinationType>
 55inline
 56nsresult
 57CallQueryReferent( T* aSource, DestinationType** aDestination )
 58  {
 59    NS_PRECONDITION(aSource, "null parameter");
 60    NS_PRECONDITION(aDestination, "null parameter");
 61
 62    return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
 63                                  reinterpret_cast<void**>(aDestination));
 64  }
 65
 66
 67class NS_COM_GLUE nsQueryReferent : public nsCOMPtr_helper
 68  {
 69    public:
 70      nsQueryReferent( nsIWeakReference* aWeakPtr, nsresult* error )
 71          : mWeakPtr(aWeakPtr),
 72            mErrorPtr(error)
 73        {
 74          // nothing else to do here
 75        }
 76
 77      virtual nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const;
 78
 79    private:
 80      nsIWeakReference*  mWeakPtr;
 81      nsresult*          mErrorPtr;
 82  };
 83
 84inline
 85const nsQueryReferent
 86do_QueryReferent( nsIWeakReference* aRawPtr, nsresult* error = 0 )
 87  {
 88    return nsQueryReferent(aRawPtr, error);
 89  }
 90
 91
 92  /**
 93   * Deprecated, use |do_GetWeakReference| instead.
 94   */
 95extern NS_COM_GLUE
 96nsIWeakReference*
 97NS_GetWeakReference( nsISupports* , nsresult* aResult=0 );
 98
 99  /**
100   * |do_GetWeakReference| is a convenience function that bundles up all the work needed
101   * to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
102   * call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
103   * It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
104   * |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
105   */
106inline
107already_AddRefed<nsIWeakReference>
108do_GetWeakReference( nsISupports* aRawPtr, nsresult* error = 0 )
109  {
110    return NS_GetWeakReference(aRawPtr, error);
111  }
112
113inline
114void
115do_GetWeakReference( nsIWeakReference* aRawPtr, nsresult* error = 0 )
116  {
117    // This signature exists solely to _stop_ you from doing a bad thing.
118    //  Saying |do_GetWeakReference()| on a weak reference itself,
119    //  is very likely to be a programmer error.
120  }
121
122template <class T>
123inline
124void
125do_GetWeakReference( already_AddRefed<T>& )
126  {
127    // This signature exists solely to _stop_ you from doing the bad thing.
128    //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
129    //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
130  }
131
132template <class T>
133inline
134void
135do_GetWeakReference( already_AddRefed<T>&, nsresult* )
136  {
137    // This signature exists solely to _stop_ you from doing the bad thing.
138    //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
139    //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
140  }
141
142#endif