Method AssembleArray

cpp/src/parquet/arrow/reader.cc:691–713

  using ListReader<IndexType>::ListReader;

  ::arrow::Result<std::shared_ptr<ChunkedArray>> AssembleArray(
      std::shared_ptr<ArrayData> data) final {
    static_assert(::arrow::internal::IsOneOf<IndexType, int32_t, int64_t>::value);
    constexpr auto expected_type_id = std::is_same_v<IndexType, int32_t>
                                          ? ::arrow::Type::LIST_VIEW
                                          : ::arrow::Type::LARGE_LIST_VIEW;
    DCHECK_EQ(this->field()->type()->id(), expected_type_id);
    DCHECK_EQ(data->buffers.size(), 2);
    const auto* offsets = reinterpret_cast<const IndexType*>(data->buffers[1]->data());
    ARROW_ASSIGN_OR_RAISE(
        auto sizes_buffer,
        AllocateResizableBuffer(sizeof(IndexType) * data->length, this->ctx_->pool));
    auto* sizes = reinterpret_cast<IndexType*>(sizes_buffer->mutable_data());
    for (int64_t i = 0; i < data->length; ++i) {
      sizes[i] = offsets[i + 1] - offsets[i];
    }
    // ListReader produces length + 1 offsets; ListView stores one offset per slot.
    data->buffers[1] = ::arrow::SliceBuffer(std::move(data->buffers[1]), /*offset=*/0,
                                            sizeof(IndexType) * data->length);
    data->buffers.push_back(std::move(sizes_buffer));
    std::shared_ptr<Array> result = ::arrow::MakeArray(data);
    return std::make_shared<ChunkedArray>(std::move(result));
  }
};

class PARQUET_NO_EXPORT FixedSizeListReader : public ListReader<int32_t> {