/// <summary>
/// Traverse the result object graph, flattening into a single list. Note that this
/// flattening must maintain relative ordering for the top level elements, since the client might
/// have passed an order expression.
/// </summary>
/// <typeparam name="TEntity">The root entity Type of the query.</typeparam>
/// <param name="list">The list of entities to add to the results.</param>
/// <param name="rootResults">The root entities. The value can be <value>null</value> if the list of root results is already known.</param>
/// <param name="includedResults">The included entities.</param>
/// <param name="visited">Map used for the lifetime of the flattening to ensure that each entity
/// is added to the results only once.</param>
/// <param name="domainServiceDescription">description for the DomainService.</param>
private static void FlattenGraph <TEntity>(IEnumerable list, List <TEntity> rootResults, List <object> includedResults, HashSet <object> visited, DomainServiceDescription domainServiceDescription)
{
if (list == null)
{
return;
}
// Queue used for breadth-first scan
Queue <IEnumerable> resultsQueue = new Queue <IEnumerable>();
resultsQueue.Enqueue(list);
IList result = rootResults;
while (resultsQueue.Count > 0)
{
foreach (object entity in resultsQueue.Dequeue())
{
if (!visited.Add(entity))
{
continue;
}
// If we already know the root results, then we don't need to copy them over to a new list.
if (result != null)
{
result.Add(entity);
}
// make sure to use the correct entity Type, taking inheritance into account
Type entityType = domainServiceDescription.GetSerializationType(entity.GetType());
PropertyDescriptorCollection properties = MetaType.GetMetaType(entityType).IncludedAssociations;
foreach (PropertyDescriptor pd in properties)
{
IEnumerable value = null;
if (typeof(IEnumerable).IsAssignableFrom(pd.PropertyType))
{
value = (IEnumerable)pd.GetValue(entity);
}
else
{
// singleton association
object singleton = pd.GetValue(entity);
if (singleton != null)
{
value = new object[] { singleton };
}
}
if (value != null)
{
resultsQueue.Enqueue(value);
}
}
}
// From now on, add everything to includedResults.
result = includedResults;
}
}