gecko-dev/xpcom/glue/nsWeakReference.cpp

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// nsWeakReference.cpp

#include "nsWeakReference.h"
#include "nsCOMPtr.h"

nsresult
nsQueryReferent::operator()( const nsIID& aIID, void** answer ) const
  {
    nsresult status;
    if ( mWeakPtr )
      {
        if ( NS_FAILED(status = mWeakPtr->QueryReferent(aIID, answer)) )
          *answer = 0;
      }
    else
      status = NS_ERROR_NULL_POINTER;

    if ( mErrorPtr )
      *mErrorPtr = status;
    return status;
  }

NS_COM_GLUE nsIWeakReference*  // or else |already_AddRefed<nsIWeakReference>|
NS_GetWeakReference( nsISupports* aInstancePtr, nsresult* aErrorPtr )
  {
    nsresult status;

    nsIWeakReference* result = nsnull;

    if ( aInstancePtr )
      {
        nsCOMPtr<nsISupportsWeakReference> factoryPtr = do_QueryInterface(aInstancePtr, &status);
        NS_ASSERTION(factoryPtr, "Oops!  You're asking for a weak reference to an object that doesn't support that.");
        if ( factoryPtr )
          {
            status = factoryPtr->GetWeakReference(&result);
          }
        // else, |status| has already been set by |do_QueryInterface|
      }
    else
      status = NS_ERROR_NULL_POINTER;

    if ( aErrorPtr )
      *aErrorPtr = status;
    return result;
  }

NS_COM_GLUE nsresult
nsSupportsWeakReference::GetWeakReference( nsIWeakReference** aInstancePtr )
  {
    if ( !aInstancePtr )
      return NS_ERROR_NULL_POINTER;

    if ( !mProxy )
      mProxy = new nsWeakReference(this);
    *aInstancePtr = mProxy;

    nsresult status;
    if ( !*aInstancePtr )
      status = NS_ERROR_OUT_OF_MEMORY;
    else
      {
        NS_ADDREF(*aInstancePtr);
        status = NS_OK;
      }

    return status;
  }

NS_IMPL_ISUPPORTS1(nsWeakReference, nsIWeakReference)

NS_IMETHODIMP
nsWeakReference::QueryReferent( const nsIID& aIID, void** aInstancePtr )
  {
    return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) : NS_ERROR_NULL_POINTER;
  }