pitrou commented on code in PR #45217: URL: https://github.com/apache/arrow/pull/45217#discussion_r1913133340
########## cpp/src/arrow/compute/kernels/vector_rank.cc: ########## @@ -28,114 +28,97 @@ namespace { // ---------------------------------------------------------------------- // Rank implementation -template <typename ValueSelector, - typename T = std::decay_t<std::invoke_result_t<ValueSelector, int64_t>>> +// A bit that is set in the sort indices when the value at the current sort index +// is the same as the value at the previous sort index. +constexpr uint64_t kDuplicateMask = 1ULL << 63; + +constexpr bool NeedsDuplicates(RankOptions::Tiebreaker tiebreaker) { + return tiebreaker != RankOptions::First; +} + +template <typename ValueSelector> +void MarkDuplicates(const NullPartitionResult& sorted, ValueSelector&& value_selector) { + using T = decltype(value_selector(int64_t{})); + + // Process non-nulls + if (sorted.non_nulls_end != sorted.non_nulls_begin) { + auto it = sorted.non_nulls_begin; + T prev_value = value_selector(*it); + while (++it < sorted.non_nulls_end) { + T curr_value = value_selector(*it); + if (curr_value == prev_value) { + *it |= kDuplicateMask; Review Comment: Ah, my bad, I missed that `*it |= kDuplicateMask` actually requires the pointee to be `uint64_t`. I'll revert this minor change. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org