Function MakeListArray

cpp/src/arrow/ipc/test_common.cc:139–189

template <typename TypeClass>
Status MakeListArray(const std::shared_ptr<Array>& child_array, int num_lists,
                     bool include_nulls, MemoryPool* pool, std::shared_ptr<Array>* out) {
  using offset_type = typename TypeClass::offset_type;
  using ArrayType = typename TypeTraits<TypeClass>::ArrayType;

  // Create the null list values
  std::vector<uint8_t> valid_lists(num_lists);
  const double null_percent = include_nulls ? 0.1 : 0;
  random_null_bytes(num_lists, null_percent, valid_lists.data());

  // Create list offsets
  const int max_list_size = 10;

  std::vector<offset_type> list_sizes(num_lists, 0);
  std::vector<offset_type> offsets(
      num_lists + 1, 0);  // +1 so we can shift for nulls. See partial sum below.
  const auto seed = static_cast<uint32_t>(child_array->length());

  if (num_lists > 0) {
    rand_uniform_int(num_lists, seed, 0, max_list_size, list_sizes.data());
    // make sure sizes are consistent with null
    std::transform(list_sizes.begin(), list_sizes.end(), valid_lists.begin(),
                   list_sizes.begin(),
                   [](offset_type size, uint8_t valid) { return valid == 0 ? 0 : size; });
    std::partial_sum(list_sizes.begin(), list_sizes.end(), ++offsets.begin());

    // Force invariants
    const auto child_length = static_cast<offset_type>(child_array->length());
    offsets[0] = 0;
    std::replace_if(
        offsets.begin(), offsets.end(),
        [child_length](offset_type offset) { return offset > child_length; },
        child_length);
  }

  offsets[num_lists] = static_cast<offset_type>(child_array->length());

  // Create offsets array
  using OffsetArrowType = typename TypeTraits<TypeClass>::OffsetType;
  std::shared_ptr<Array> offsets_array;
  ArrayFromVector<OffsetArrowType, offset_type>(offsets, &offsets_array);

  // Create null bitmap
  std::shared_ptr<Buffer> null_bitmap;
  RETURN_NOT_OK(GetBitmapFromVector(valid_lists, &null_bitmap));

  // Use FromArrays which supports nulls via null_bitmap parameter
  ARROW_ASSIGN_OR_RAISE(*out, ArrayType::FromArrays(*offsets_array, *child_array, pool,
                                                    null_bitmap, kUnknownNullCount));
  return Status::OK();
}

Status MakeRandomListViewArray(const std::shared_ptr<Array>& child_array, int num_lists,
                               bool include_nulls, MemoryPool* pool,