Function OnBitPackedRun

cpp/src/arrow/util/rle_encoding_internal.h:675–675

  struct {
    Callable func;
    auto OnBitPackedRun(BitPackedRun run) { return func(std::move(run)); }
    auto OnRleRun(RleRun run) { return func(std::move(run)); }
  } handler{std::move(func)};