sol2/examples/source/coroutine.cpp

#define SOL_ALL_SAFETIES_ON 1
#include <sol/sol.hpp>

#include <string>
#include <iostream>

int main() {
	std::cout << "=== coroutine ===" << std::endl;

	sol::state lua;
	std::vector<sol::coroutine> tasks;

	lua.open_libraries(sol::lib::base, sol::lib::coroutine);

	sol::thread runner_thread = sol::thread::create(lua);

	lua.set_function("start_task",
	     [&runner_thread, &tasks](
	          sol::function f, sol::variadic_args va) {
		     // You must ALWAYS get the current state
		     sol::state_view runner_thread_state
		          = runner_thread.state();
		     // Put the task in our task list to keep it alive
		     // and track it
		     std::size_t task_index = tasks.size();
		     tasks.emplace_back(runner_thread_state, f);
		     sol::coroutine& f_on_runner_thread
		          = tasks[task_index];
		     // call coroutine with arguments that came
		     // from main thread / other thread
		     // pusher for `variadic_args` and other sol types
		     // will transfer the arguments from the calling
		     // thread to the runner thread automatically for
		     // you using `lua_xmove` internally
		     int wait = f_on_runner_thread(va);
		     std::cout << "First return: " << wait
		               << std::endl;
		     // When you call it again, you don't need new
		     // arguments (they remain the same from the first
		     // call)
		     f_on_runner_thread();
		     std::cout << "Second run complete: " << wait
		               << std::endl;
	     });

	lua.script(
	     R"(
function main(x, y, z)
	-- do something
	coroutine.yield(20)
	-- do something else
	-- do ...
	print(x, y, z)
end

function main2(x, y)
	coroutine.yield(10)
	print(x, y)
end

	start_task(main, 10, 12, 8)
	start_task(main2, 1, 2)
)");

	std::cout << std::endl;

	return 0;
}