private IEnumerable<Exceptional<DBObjectStream>> GetReferenceObjects(DBObjectStream myStartingDBObject, TypeAttribute interestingAttributeEdge, GraphDBType myStartingDBObjectType, DBTypeManager myDBTypeManager)
{
if (interestingAttributeEdge.GetDBType(myDBTypeManager).IsUserDefined || interestingAttributeEdge.IsBackwardEdge)
{
switch (interestingAttributeEdge.KindOfType)
{
case KindsOfType.SingleReference:
yield return LoadDBObjectStream(interestingAttributeEdge.GetDBType(myDBTypeManager), ((ASingleReferenceEdgeType)myStartingDBObject.GetAttribute(interestingAttributeEdge.UUID)).GetUUID());
break;
case KindsOfType.SetOfReferences:
if (interestingAttributeEdge.IsBackwardEdge)
{
//get backwardEdge
var beStream = LoadDBBackwardEdgeStream(myStartingDBObjectType, myStartingDBObject.ObjectUUID);
if (beStream.Failed())
{
throw new GraphDBException(new Error_ExpressionGraphInternal(null, String.Format("Error while trying to get BackwardEdge of the DBObject: \"{0}\"", myStartingDBObject.ToString())));
}
if (beStream.Value.ContainsBackwardEdge(interestingAttributeEdge.BackwardEdgeDefinition))
{
foreach (var aBackwardEdgeObject in LoadListOfDBObjectStreams(interestingAttributeEdge.BackwardEdgeDefinition.TypeUUID, beStream.Value.GetBackwardEdgeUUIDs(interestingAttributeEdge.BackwardEdgeDefinition)))
{
yield return aBackwardEdgeObject;
}
}
}
else
{
foreach (var aDBOStream in LoadListOfDBObjectStreams(interestingAttributeEdge.GetDBType(myDBTypeManager), ((ASetOfReferencesEdgeType)myStartingDBObject.GetAttribute(interestingAttributeEdge.UUID)).GetAllReferenceIDs()))
{
yield return aDBOStream;
}
}
break;
case KindsOfType.SetOfNoneReferences:
case KindsOfType.ListOfNoneReferences:
default:
throw new GraphDBException(new Error_ExpressionGraphInternal(new System.Diagnostics.StackTrace(true), String.Format("The attribute \"{0}\" has an invalid KindOfType \"{1}\"!", interestingAttributeEdge.Name, interestingAttributeEdge.KindOfType.ToString())));
}
}
else
{
throw new GraphDBException(new Error_ExpressionGraphInternal(new System.Diagnostics.StackTrace(true), String.Format("The attribute \"{0}\" is no reference attribute.", interestingAttributeEdge.Name)));
}
yield break;
}