coro/corocoro.cpp

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 "corotask.hpp"   // for CoroTask

CoroTask coro()
{
  std::cout << "    coro(): PART1\n";
  co_await std::suspend_always{};     // SUSPEND
  std::cout << "    coro(): PART2\n";
}

CoroTask callCoro()
{
  std::cout << "  callCoro(): CALL coro()\n";
  auto sub = coro();                  // init sub coroutine
  while (sub.resume()) {              // RESUME sub coroutine
    std::cout << "  callCoro(): coro() suspended\n";
  }
  std::cout << "  callCoro(): coro() done\n";
  co_await std::suspend_always{};     // SUSPEND
  std::cout << "  callCoro(): END\n";
}

int main()
{
  auto coroTask = callCoro();           // initialize coroutine
  std::cout << "MAIN: callCoro() initialized\n";

  while (coroTask.resume()) {           // RESUME
    std::cout << "MAIN: callCoro() suspended\n";
  }

  std::cout << "MAIN: callCoro() done\n";
}