8 m_begin(buffer.cbegin()), m_end(buffer.cend()) {}
11 m_begin(r.begin()), m_end(r.end()) {}
14 m_begin(begin), m_end(end) {}
18 if (m_begin == m_end) {
21 std::streamsize remaining = std::distance(m_begin, m_end);
22 std::streamsize consume = std::min(remaining, n);
23 std::copy(m_begin, m_begin + consume, buf);
24 std::advance(m_begin, consume);