Class EdgeIterator

src/svgfill/src/graph_2d.h:447–514

    // Edge iterator class
    class EdgeIterator {
    public:
        typedef std::forward_iterator_tag iterator_category;
        typedef Edge value_type;
        typedef ptrdiff_t difference_type;
        typedef const Edge* pointer;
        typedef const Edge& reference;

        EdgeIterator() : outer_it_(), inner_it_(), graph_(nullptr) {}
        EdgeIterator(const Graph2D* graph, typename std::map<Point_2, std::set<Point_2>>::const_iterator outer_it)
            : outer_it_(outer_it), graph_(graph) {
            if (outer_it_ != graph_->adjacency_list.end()) {
                inner_it_ = outer_it_->second.begin();
                advance_to_valid();
            }
        }

        reference operator*() const {
            current_edge_ = Edge(outer_it_->first, *inner_it_);
            return current_edge_;
        }

        pointer operator->() const {
            current_edge_ = Edge(outer_it_->first, *inner_it_);
            return &current_edge_;
        }

        EdgeIterator& operator++() {
            ++inner_it_;
            advance_to_valid();
            return *this;
        }

        EdgeIterator operator++(int) {
            EdgeIterator tmp = *this;
            ++(*this);
            return tmp;
        }

        bool operator==(const EdgeIterator& other) const {
            return outer_it_ == other.outer_it_ && (outer_it_ == graph_->adjacency_list.end() || inner_it_ == other.inner_it_);
        }

        bool operator!=(const EdgeIterator& other) const {
            return !(*this == other);
        }

    private:
        void advance_to_valid() {
            while (outer_it_ != graph_->adjacency_list.end()) {
                while (inner_it_ != outer_it_->second.end() && *inner_it_ < outer_it_->first) {
                    ++inner_it_;
                }
                if (inner_it_ != outer_it_->second.end()) {
                    break;
                }
                ++outer_it_;
                if (outer_it_ != graph_->adjacency_list.end()) {