AcDbGraph

graph.h

This class provides a generic graph container implementation. Two other classes are also involved in the graph mechanism: AcDbGraphNode and AcDbGraphStack. 

Detection for circular references is done by internally creating a duplicate set of references in each node and then trimming away all leaf nodes, which terminate without circularity. If any nodes remain in the duplicate graph, those nodes exist in a cycle. AcDbGraph::findCycles() is used to set up the internal cycle information and enable several query methods to return information about any cycles found.

AcDbGraphNode, AcDbGraphStack, AcDbXrefGraph, AcDbXrefGraphNode