Method Finalize

cpp/src/arrow/compute/kernels/hash_aggregate.cc:864–911

  }

  Result<Datum> Finalize() override {
    // We initialize the null bitmap with first_is_nulls and last_is_nulls
    // then update it depending on has_values
    ARROW_ASSIGN_OR_RAISE(auto first_null_bitmap, first_is_nulls_.Finish());
    ARROW_ASSIGN_OR_RAISE(auto last_null_bitmap, last_is_nulls_.Finish());
    ARROW_ASSIGN_OR_RAISE(auto has_values, has_values_.Finish());

    auto raw_first_null_bitmap = first_null_bitmap->mutable_data();
    auto raw_last_null_bitmap = last_null_bitmap->mutable_data();
    auto raw_has_values = has_values->data();

    if (options_.skip_nulls) {
      for (int i = 0; i < num_groups_; i++) {
        const bool has_value = bit_util::GetBit(has_values->data(), i);
        bit_util::SetBitTo(raw_first_null_bitmap, i, has_value);
        bit_util::SetBitTo(raw_last_null_bitmap, i, has_value);
      }
    } else {
      for (int i = 0; i < num_groups_; i++) {
        // If first is null, we set the mask to false to output null
        if (bit_util::GetBit(raw_first_null_bitmap, i)) {
          bit_util::SetBitTo(raw_first_null_bitmap, i, false);
        } else {
          bit_util::SetBitTo(raw_first_null_bitmap, i,
                             bit_util::GetBit(raw_has_values, i));
        }
      }
      for (int i = 0; i < num_groups_; i++) {
        // If last is null, we set the mask to false to output null
        if (bit_util::GetBit(raw_last_null_bitmap, i)) {
          bit_util::SetBitTo(raw_last_null_bitmap, i, false);
        } else {
          bit_util::SetBitTo(raw_last_null_bitmap, i,
                             bit_util::GetBit(raw_has_values, i));
        }
      }
    }

    auto firsts =
        ArrayData::Make(type_, num_groups_, {std::move(first_null_bitmap), nullptr});
    auto lasts =
        ArrayData::Make(type_, num_groups_, {std::move(last_null_bitmap), nullptr});
    ARROW_ASSIGN_OR_RAISE(firsts->buffers[1], firsts_.Finish());
    ARROW_ASSIGN_OR_RAISE(lasts->buffers[1], lasts_.Finish());

    return ArrayData::Make(out_type(), num_groups_, {nullptr},
                           {std::move(firsts), std::move(lasts)});
  }

  std::shared_ptr<DataType> out_type() const override {
    return struct_({field("first", type_), field("last", type_)});