Method is_valid

src/svgfill/src/graph_2d.h:175–202

    }

    bool is_valid() const {
        typedef CGAL::Box_intersection_d::Box_with_handle_d<double, 2, size_t, CGAL::Box_intersection_d::ID_EXPLICIT> Box;
        std::vector<Box> boxes;
        std::vector<CGAL::Segment_2<Kernel>> segments;
        for (const auto& p : adjacency_list) {
            for (const auto& q : p.second) {
                if (p.first < q) {
                    segments.emplace_back(p.first, q);
                }
            }
        }
        for (auto it = segments.begin(); it != segments.end(); ++it) {
            boxes.emplace_back(it->bbox(), std::distance(segments.begin(), it));
        }
        bool any = false;
        CGAL::box_self_intersection_d(boxes.begin(), boxes.end(), [this, &segments, &any](const Box& a, const Box& b) {
            auto& seg1 = segments[a.handle()];
            auto& seg2 = segments[b.handle()];
            // Skip topologically connected segments
            if (seg1.source() == seg2.source() || seg1.source() == seg2.target() || seg1.target() == seg2.source() || seg1.target() == seg2.target()) {
                return;
            }
            if (CGAL::do_intersect(seg1, seg2)) {
                any = true;
            }
        });
        return any;
    }

    // Eliminates a vertex with exactly two neighbors by connecting its neighbors
    typename std::map<Point_2, std::set<Point_2>>::iterator eliminate_vertex(typename std::map<Point_2, std::set<Point_2>>::iterator it) {