Method LoadCommon

cpp/src/arrow/ipc/reader.cc:302–335

  }

  Status LoadCommon(Type::type type_id, bool allow_validity_bitmap = true) {
    DCHECK_NE(out_, nullptr);
    // This only contains the length and null count, which we need to figure
    // out what to do with the buffers. For example, if null_count == 0, then
    // we can skip that buffer without reading from shared memory
    RETURN_NOT_OK(GetFieldMetadata(field_index_++, out_));

    if (::arrow::internal::has_variadic_buffers(type_id)) {
      ARROW_ASSIGN_OR_RAISE(auto data_buffer_count,
                            GetVariadicCount(variadic_count_index_++));
      const int64_t start = static_cast<int64_t>(out_->buffers.size());
      // NOTE: this must be done before any other call to `GetBuffer` because
      // BatchDataReadRequest will keep pointers to `std::shared_ptr<Buffer>`
      // objects.
      out_->buffers.resize(start + data_buffer_count);
    }

    if (internal::HasValidityBitmap(type_id, metadata_version_)) {
      // Extract null bitmap which is common to all arrays except for unions
      // and nulls.
      if (out_->null_count != 0) {
        if (allow_validity_bitmap) {
          RETURN_NOT_OK(GetBuffer(buffer_index_, &out_->buffers[0]));
        } else {
          // Caller did not allow this
          return Status::Invalid("Cannot read ", ::arrow::internal::ToTypeName(type_id),
                                 " array with top-level validity bitmap");
        }
      }
      buffer_index_++;
    }

    return Status::OK();
  }

  template <typename TYPE>
  Status LoadPrimitive(Type::type type_id) {