438 struct SSVertex {  struct
439     SSVertex(Vertex* v) : fVertex(v), fPrev(nullptr), fNext(nullptr) {}  in SSVertex()  function
446     SSEdge(Edge* edge, SSVertex* prev, SSVertex* next)  in SSEdge()
451     SSVertex* fPrev;
452     SSVertex* fNext;
455 typedef std::unordered_map<Vertex*, SSVertex*> SSVertexMap;
1809     SSVertex* ssv = alloc.make<SSVertex>(dest);  in apply()
1891                 SSVertex* ssPrev = ssVertices[prevVertex];  in collapse_overlap_regions()
1893                     ssPrev = ssVertices[prevVertex] = alloc.make<SSVertex>(prevVertex);  in collapse_overlap_regions()
1895                 SSVertex* ssNext = ssVertices[nextVertex];  in collapse_overlap_regions()
1897                     ssNext = ssVertices[nextVertex] = alloc.make<SSVertex>(nextVertex);  in collapse_overlap_regions()