ranges/processview0.hpp

The following code example is taken from the book
C++23 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2026
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <ranges>
#include <utility>

// new view type to process all elements:
template<std::ranges::range InnerRgT>
struct ProcessView : std::ranges::view_interface<ProcessView<InnerRgT>>
{
  private:
    InnerRgT innerRange;  // view, ref_view to range, or owning view to range
  public:
    template<std::ranges::range RgT>
    ProcessView(RgT&& rg)
     : innerRange(std::forward<RgT>(rg)) {
    }
    auto begin() { return innerRange.begin(); }
    auto end() { return innerRange.end(); }
};

// deduction guide to deal with lvalues and rvalues:
template<std::ranges::range RgT>
ProcessView(RgT&& rg) -> ProcessView<std::ranges::views::all_t<RgT>>;