ranges/printcoll.hpp

The following code example is taken from the book
C++20 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2021
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <iostream>
#include <ranges>

template<typename T>
void printColl(T&& obj, int level = 0)
{
  if constexpr(std::same_as<std::remove_cvref_t<T>, std::string>) {
    std::cout << "\"" << obj << "\"";
  }
  else if constexpr(std::ranges::input_range<T>) {
    std::cout << '[';
    for (auto pos = obj.begin(); pos != obj.end(); ++pos) {
       printColl(*pos, level+1);
       if (std::ranges::next(pos) != obj.end()) {
         std::cout << ' ';
       }
    }
    std::cout << ']';
  }
  else {
    std::cout << obj;
  }
  if (level == 0) std::cout << '\n';
}