Function lazy_copy_converting

cpp/src/arrow/util/range_benchmark.cc:98–109

std::copy with a lazy range which does static cast. Should be the same performance as std::copy with differently typed iterators

// std::copy with a lazy range which does static cast.
// Should be the same performance as std::copy with differently typed iterators
void lazy_copy_converting(benchmark::State& state) {
  auto source = generate_junk<int64_t>(kSize);
  std::vector<int32_t> target(kSize);
  auto lazy_range = internal::MakeLazyRange(
      [&source](int64_t index) { return static_cast<int32_t>(source[index]); },
      source.size());

  for (auto _ : state) {
    std::copy(lazy_range.begin(), lazy_range.end(), target.begin());
  }
  state.SetItemsProcessed(state.iterations() * kSize);
}

BENCHMARK(lazy_copy_converting);