if (mNextAssertion) mNextAssertion->AddRef();
InMemoryAssertionEnumeratorImpl::InMemoryAssertionEnumeratorImpl(                 InMemoryDataSource* aDataSource,                 nsIRDFResource* aSource,                 nsIRDFResource* aProperty,                 nsIRDFNode* aTarget,                 PRBool aTruthValue)    : mDataSource(aDataSource),      mSource(aSource),      mProperty(aProperty),      mTarget(aTarget),      mValue(nsnull),      mCount(0),      mTruthValue(aTruthValue),      mNextAssertion(nsnull){    NS_INIT_REFCNT();    NS_ADDREF(mDataSource);    NS_IF_ADDREF(mSource);    NS_ADDREF(mProperty);    NS_IF_ADDREF(mTarget);    if (mSource) {        mNextAssertion = mDataSource->GetForwardArcs(mSource);    }    else {        mNextAssertion = mDataSource->GetReverseArcs(mTarget);    }}