Method DoTell

cpp/src/arrow/io/memory.cc:282–285

bool BufferReader::closed() const { return !is_open_; }

Result<int64_t> BufferReader::DoTell() const {
  RETURN_NOT_OK(CheckClosed());
  return position_;
}

Result<std::string_view> BufferReader::DoPeek(int64_t nbytes) {
  RETURN_NOT_OK(CheckClosed());