Method Exec

cpp/src/arrow/compute/kernels/scalar_cast_nested.cc:148–183

  using dest_offset_type = typename DestType::offset_type;

  static Status Exec(KernelContext* ctx, const ExecSpan& batch, ExecResult* out) {
    const CastOptions& options = CastState::Get(ctx);

    auto child_type = checked_cast<const DestType&>(*out->type()).value_type();

    const ArraySpan& in_array = batch[0].array;

    ArrayData* out_array = out->array_data().get();
    ARROW_ASSIGN_OR_RAISE(out_array->buffers[0],
                          GetOrCopyNullBitmapBuffer(in_array, ctx->memory_pool()));

    const auto& in_type = checked_cast<const FixedSizeListType&>(*in_array.type);
    const int32_t list_size = in_type.list_size();

    // Allocate a new offsets buffer
    ARROW_ASSIGN_OR_RAISE(out_array->buffers[1],
                          ctx->Allocate(sizeof(dest_offset_type) * (batch.length + 1)));
    auto* offsets = out_array->GetMutableValues<dest_offset_type>(1);
    dest_offset_type offset = 0;
    for (int64_t i = 0; i <= batch.length; ++i) {
      offsets[i] = offset;
      offset += list_size;
    }

    // Handle values
    std::shared_ptr<ArrayData> values = in_array.child_data[0].ToArrayData();
    if (in_array.offset > 0) {
      values = values->Slice(in_array.offset * list_size, in_array.length * list_size);
    }
    ARROW_ASSIGN_OR_RAISE(Datum cast_values,
                          Cast(values, child_type, options, ctx->exec_context()));
    DCHECK(cast_values.is_array());
    out_array->child_data.push_back(cast_values.array());

    return Status::OK();
  }
};

template <typename SrcType>