Class TDoubleIterator

util/string/split_ut.cpp:814–855

    }

    class TDoubleIterator {
    public:
        using iterator_category = std::input_iterator_tag;
        using value_type = int;
        using pointer = void;
        using reference = int;
        using const_reference = int;
        using difference_type = ptrdiff_t;

        TDoubleIterator() = default;

        TDoubleIterator(const char* ptr)
            : Ptr_(ptr)
        {
        }

        TDoubleIterator operator++() {
            Ptr_ += 2;
            return *this;
        }

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

        friend bool operator==(TDoubleIterator l, TDoubleIterator r) {
            return l.Ptr_ == r.Ptr_;
        }

        friend bool operator!=(TDoubleIterator l, TDoubleIterator r) {
            return l.Ptr_ != r.Ptr_;
        }

        int operator*() const {
            return (*Ptr_ - '0') * 10 + *(Ptr_ + 1) - '0';
        }

    private:
        const char* Ptr_ = nullptr;
    };

    Y_UNIT_TEST(TestInputIterator) {
        const char* beg = "1213002233000011";