Function PutOffsets

cpp/src/arrow/array/concatenate.cc:179–211

template <typename Offset>
Result<OffsetBufferOpOutcome> PutOffsets(const Buffer& src, Offset first_offset,
                                         Offset* dst, Range* values_range) {
  if (src.size() == 0) {
    // It's allowed to have an empty offsets buffer for a 0-length array
    // (see Array::Validate)
    values_range->offset = 0;
    values_range->length = 0;
    return OffsetBufferOpOutcome::kOk;
  }

  // Get the range of offsets to transfer from src
  auto src_begin = src.data_as<Offset>();
  auto src_end = reinterpret_cast<const Offset*>(src.data() + src.size());

  // Compute the range of values which is spanned by this range of offsets
  values_range->offset = src_begin[0];
  values_range->length = *src_end - values_range->offset;
  if (ARROW_PREDICT_FALSE(first_offset >
                          std::numeric_limits<Offset>::max() - values_range->length)) {
    return OffsetBufferOpOutcome::kOffsetOverflow;
  }

  // Write offsets into dst, ensuring that the first offset written is
  // first_offset
  auto displacement = first_offset - src_begin[0];
  // NOTE: Concatenate can be called during IPC reads to append delta dictionaries.
  // Avoid UB on non-validated input by doing the addition in the unsigned domain.
  // (the result can later be validated using Array::ValidateFull)
  std::transform(src_begin, src_end, dst, [displacement](Offset offset) {
    return SafeSignedAdd(offset, displacement);
  });
  return OffsetBufferOpOutcome::kOk;
}

template <typename offset_type>
Result<OffsetBufferOpOutcome> PutListViewOffsets(const ArrayData& input,