example.cpp

class ConstIterator {
   public:
    friend class ConcurrentHashMap;

    const value_type& operator*() const {
      return *it_;
    }

    const value_type* operator->() const {
      return &*it_;
    }

    ConstIterator& operator++() {
      ++it_;
      next();
      return *this;
    }

    bool operator==(const ConstIterator& o) const {
      return it_ == o.it_ && segment_ == o.segment_;
    }

    bool operator!=(const ConstIterator& o) const {
      return !(*this == o);
    }

    ConstIterator& operator=(const ConstIterator& o) = delete;

    ConstIterator& operator=(ConstIterator&& o) noexcept {
      if (this != &o) {
        it_ = std::move(o.it_);
        segment_ = std::exchange(o.segment_, uint64_t(NumShards));
        parent_ = std::exchange(o.parent_, nullptr);
      }
      return *this;
    }

    ConstIterator(const ConstIterator& o) = delete;

    ConstIterator(ConstIterator&& o) noexcept
        : it_(std::move(o.it_)),
          segment_(std::exchange(o.segment_, uint64_t(NumShards))),
          parent_(std::exchange(o.parent_, nullptr)) {}

    ConstIterator(const ConcurrentHashMap* parent, uint64_t segment)
        : segment_(segment), parent_(parent) {}
};