Method DoNext

util/stream/zerocopy_output_ut.cpp:17–25

private:
    size_t DoNext(void** ptr) override {
        if (S_.size() == S_.capacity()) {
            S_.reserve(FastClp2(S_.capacity() + 1));
        }
        size_t previousSize = S_.size();
        S_.resize(S_.capacity());
        *ptr = S_.begin() + previousSize;
        return S_.size() - previousSize;
    }

    void DoUndo(size_t len) override {
        Y_ENSURE(len <= S_.size());