question: private static List findLabeledEdgeRings ( Collection dirEdges ) { List edgeRingStarts = new ArrayList ( ) ; long currLabel = 1 ; for ( Iterator i = dirEdges . iterator ( ) ; i . hasNext ( ) ; ) { PolygonizeDirectedEdge de = ( PolygonizeDirectedEdge ) i . next ( ) ; if ( de . isMarked ( ) ) continue ; if ( de . getLabel ( ) >= 0 ) continue ; edgeRingStarts . add ( de ) ; List edges = EdgeRing . findDirEdgesInRing ( de ) ; label ( edges , currLabel ) ; currLabel ++ ; } return edgeRingStarts ; }
target:  Finds and labels all edgerings in the graph. The edge rings are labeling with unique integers. The labeling allows detecting cut edges.