felipecrv commented on code in PR #35036:
URL: https://github.com/apache/arrow/pull/35036#discussion_r1163239647
##########
cpp/src/arrow/util/ree_util.cc:
##########
@@ -47,6 +47,25 @@ int64_t LogicalNullCount(const ArraySpan& span) {
return null_count;
}
+template <typename RunEndCType>
+void SetLogicalNullBits(const ArraySpan& span, uint8_t* out_bitmap, int64_t
out_offset) {
+ const auto& values = ValuesArray(span);
+ const auto& values_bitmap = values.buffers[0].data;
+
+ RunEndEncodedArraySpan<RunEndCType> ree_span(span);
+ auto end = ree_span.end();
+ for (auto it = ree_span.begin(); it != end; ++it) {
+ const bool is_null =
+ values_bitmap &&
+ !bit_util::GetBit(values_bitmap, values.offset +
it.index_into_array());
+ if (is_null) {
+ for (int64_t i = 0; i < it.run_length(); i++) {
+ bit_util::SetBit(out_bitmap, it.logical_position() + i + out_offset);
+ }
+ }
Review Comment:
Don't you have to set the `0`s as well? Assuming input is pre-zeroed is OK
as long it's clearly documents. Not setting zeroes has an advantage: allows
this to be used to implement a logical OR between an existing bitmap and one
derived from the REE.
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