checkNoSelfIntersectingRing method

void checkNoSelfIntersectingRing(EdgeIntersectionList eiList)

Check that a ring does not self-intersect, except at its endpoints. Algorithm is to count the number of times each node along edge occurs. If any occur more than once, that must be a self-intersection.

Implementation

void checkNoSelfIntersectingRing(EdgeIntersectionList eiList) {
  Set nodeSet = new SplayTreeSet();
  bool isFirst = true;
  for (Iterator i = eiList.iterator(); i.moveNext();) {
    EdgeIntersection ei = i.current as EdgeIntersection;
    if (isFirst) {
      isFirst = false;
      continue;
    }
    if (nodeSet.contains(ei.coord)) {
      validErr = new TopologyValidationError.withCoordinate(
          TopologyValidationError.RING_SELF_INTERSECTION, ei.coord);
      return;
    } else {
      nodeSet.add(ei.coord);
    }
  }
}