// Test for the presence of an optional table in the supplied sub node tree
public bool IsTablePresent(BTree <Node> subNodeTree, NID nid)
{
return(subNodeTree != null && NDB.LookupSubNode(subNodeTree, nid) != null);
}
// Second form takes a node ID for a node in the supplied sub node tree
public IEnumerable <T> ReadTable <T>(FileStream fs, BTree <Node> subNodeTree, NID nid, PropertyGetters <T> g,
Action <T, UInt32> idGetter = null, Action <T, Property> storeProp = null) where T : new()
{
BTree <Node> childSubNodeTree;
var rn = ndb.LookupSubNodeAndReadItsSubNodeBtree(fs, subNodeTree, nid, out childSubNodeTree);
if (rn == null)
{
throw new XstException("Node block does not exist");
}
return(ReadTableInternal <T>(fs, childSubNodeTree, rn.DataBid, g, idGetter, storeProp));
}