nsAutoString flags; mRoot->GetAttr(kNameSpaceID_None, nsXULAtoms::flags, flags);
rv = mRules.Clear(); if (NS_FAILED(rv)) return rv;
nsXULTemplateBuilder::InitializeRuleNetwork(){    NS_PRECONDITION(mRoot != nsnull, "not initialized");    if (! mRoot)        return NS_ERROR_NOT_INITIALIZED;    // Determine if there are any special settings we need to observe    mFlags = 0;    nsAutoString flags;    mRoot->GetAttr(kNameSpaceID_None, nsXULAtoms::flags, flags);    if (flags.Find(NS_LITERAL_STRING("dont-test-empty")) >= 0)        mFlags |= eDontTestEmpty;    // Initialize the rule network    mRules.Clear();    mRules.Clear();    mRDFTests.Clear();    ComputeContainmentProperties();    mContainerVar = mRules.CreateAnonymousVariable();    mMemberVar = mRules.CreateAnonymousVariable();    return NS_OK;}