C++/17 Generator CodeGen

////////////////////////////////////////////////////////////////////
// Scenario 1 - std::experimental::generator
auto positive() -> generator<int> {
   int val = 0;
   while (true)
      __yield_value ++val;
}

for (auto&& i : positive())
   printf("%d\n", i);



/////////////////////////////////////////////////////////////////////
// Scenario 2 - light-weight but hard-coded version
struct positive_iterator {
   int& operator*() { return val; }
   positive_iterator& operator++() { val++; return *this; }
   bool operator!=(const positive_iterator& other) { return true; }
private:
   int val = 1;
};

struct light_generator {
   auto begin() { return positive_iterator {}; }
   auto end() { return positive_iterator {}; }
};

for (auto&& i : light_generator())
   printf("%d\n", i);