Function ComputeDataPreallocate

cpp/src/arrow/compute/exec.cc:286–308

};

void ComputeDataPreallocate(const DataType& type,
                            std::vector<BufferPreallocation>* widths) {
  if (is_fixed_width(type.id()) && type.id() != Type::NA) {
    widths->emplace_back(checked_cast<const FixedWidthType&>(type).bit_width());
    return;
  }
  // Preallocate binary and list offsets
  switch (type.id()) {
    case Type::BINARY:
    case Type::STRING:
    case Type::LIST:
    case Type::MAP:
      widths->emplace_back(32, /*added_length=*/1);
      return;
    case Type::LARGE_BINARY:
    case Type::LARGE_STRING:
    case Type::LARGE_LIST:
      widths->emplace_back(64, /*added_length=*/1);
      return;
    default:
      break;
  }
}

}  // namespace