req_sketch req_sketch::deserialize()

in req/include/req_sketch_impl.hpp [446:508]
54 lines of code
12 McCabe index (conditional complexity)

req_sketch<T, C, A> req_sketch<T, C, A>::deserialize(std::istream& is, const SerDe& sd, const C& comparator, const A& allocator) {
  const auto preamble_ints = read<uint8_t>(is);
  const auto serial_version = read<uint8_t>(is);
  const auto family_id = read<uint8_t>(is);
  const auto flags_byte = read<uint8_t>(is);
  const auto k = read<uint16_t>(is);
  const auto num_levels = read<uint8_t>(is);
  const auto num_raw_items = read<uint8_t>(is);

  check_preamble_ints(preamble_ints, num_levels);
  check_serial_version(serial_version);
  check_family_id(family_id);

  if (!is.good()) throw std::runtime_error("error reading from std::istream");
  const bool is_empty = flags_byte & (1 << flags::IS_EMPTY);
  const bool hra = flags_byte & (1 << flags::IS_HIGH_RANK);
  if (is_empty) return req_sketch(k, hra, comparator, allocator);

  optional<T> tmp; // space to deserialize min and max
  optional<T> min_item;
  optional<T> max_item;

  const bool raw_items = flags_byte & (1 << flags::RAW_ITEMS);
  const bool is_level_0_sorted = flags_byte & (1 << flags::IS_LEVEL_ZERO_SORTED);
  std::vector<Compactor, AllocCompactor> compactors(allocator);

  uint64_t n = 1;
  if (num_levels > 1) {
    n = read<uint64_t>(is);
    sd.deserialize(is, &*tmp, 1);
    // serde call did not throw, repackage and cleanup
    min_item.emplace(*tmp);
    (*tmp).~T();
    sd.deserialize(is, &*tmp, 1);
    // serde call did not throw, repackage and cleanup
    max_item.emplace(*tmp);
    (*tmp).~T();
  }

  if (raw_items) {
    compactors.push_back(Compactor::deserialize(is, sd, comparator, allocator, is_level_0_sorted, k, num_raw_items, hra));
  } else {
    for (size_t i = 0; i < num_levels; ++i) {
      compactors.push_back(Compactor::deserialize(is, sd, comparator, allocator, i == 0 ? is_level_0_sorted : true, hra));
    }
  }
  if (num_levels == 1) {
    const auto begin = compactors[0].begin();
    const auto end = compactors[0].end();
    n = compactors[0].get_num_items();
    auto min_it = begin;
    auto max_it = begin;
    for (auto it = begin; it != end; ++it) {
      if (comparator(*it, *min_it)) min_it = it;
      if (comparator(*max_it, *it)) max_it = it;
    }
    min_item.emplace(*min_it);
    max_item.emplace(*max_it);
  }

  if (!is.good()) throw std::runtime_error("error reading from std::istream");
  return req_sketch(k, hra, n, std::move(min_item), std::move(max_item), std::move(compactors), comparator);
}