view.cc

#include <utility>
#include <vector>

template<typename UnderlyingRangeType>
struct some_range_view {
  some_range_view(UnderlyingRangeType range) : storage_(std::forward<UnderlyingRangeType>(range)) {}

  UnderlyingRangeType storage_;
};

template<typename UnderlyingRangeType>
// UnderlyingRangeType&& has more language magic in it, namely "forwarding reference".
some_range_view<UnderlyingRangeType> make_some_range_view(UnderlyingRangeType&& range) {
  return some_range_view<UnderlyingRangeType>(std::forward<UnderlyingRangeType>(range));
}

int main() {
  {
    auto view = make_some_range_view(std::vector<int>());
    static_assert(std::is_same<decltype(view.storage_), std::vector<int>>::value, "");
  }
  {
    std::vector<int> v;
    auto view = make_some_range_view(v);
    static_assert(std::is_same<decltype(view.storage_), std::vector<int>&>::value, "");
  }
  {
    const std::vector<int> v;
    auto view = make_some_range_view(v);
    static_assert(std::is_same<decltype(view.storage_), const std::vector<int>&>::value, "");
  }
}