[GitHub] [arrow] pitrou commented on a change in pull request #8623: ARROW-10345: [C++][Compute] Fix NaN handling in sorting and topn kernels

[GitBox <gi...@apache.org>]

pitrou commented on a change in pull request #8623:
URL: https://github.com/apache/arrow/pull/8623#discussion_r520605189



##########
File path: cpp/src/arrow/compute/kernels/vector_sort.cc
##########
@@ -30,6 +32,58 @@ namespace internal {
 
 namespace {
 
+// NOTE: std::partition is usually faster than std::stable_partition.
+
+struct NonStablePartitioner {
+  template <typename Predicate>
+  uint64_t* operator()(uint64_t* indices_begin, uint64_t* indices_end, Predicate&& pred) {
+    return std::partition(indices_begin, indices_end, std::forward<Predicate>(pred));
+  }
+};
+
+struct StablePartitioner {
+  template <typename Predicate>
+  uint64_t* operator()(uint64_t* indices_begin, uint64_t* indices_end, Predicate&& pred) {
+    return std::stable_partition(indices_begin, indices_end,
+                                 std::forward<Predicate>(pred));
+  }
+};
+
+// Move Nulls to end of array. Return where Null starts.
+template <typename ArrayType, typename Partitioner>

Review comment:
       @bkietz Apparently one can't use a template function as template argument. Is that right?
   (I originally wanted to pass `std::partition` as a template function argument)




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