test.cpp

#include <tuple>
#include <iostream>
#include <cmath>

#include <stlab/future.hpp>
#include <stlab/channel.hpp>

using namespace stlab;
using namespace std;
using namespace std::chrono;

struct render {
    process_state_scheduled _state = await_forever;

    int _params;

    void await(int params) {
        _state = await_immediate;
        _params = params;
    }

    double yield() {
        this_thread::sleep_for(2s);
        _state = await_forever;
        return sqrt(_params);
    }

    void close() { if (_state == await_immediate) _state = yield_immediate; }

    const auto& state() const {
        return _state;
    }
};

int main() {

    sender<int> send;
    receiver<int> receive;

    tie(send, receive) = channel<int>(default_scheduler());

    send(1);
    send(2);
    send(3);

    auto hold = receive
        | render()
        | [](double x){ cout << x << '\n'; };

    receive.set_ready();

#if 0
    send(1);
    send(2);
    send(3);
#endif
    this_thread::sleep_for(1s);
    send(4);
    send(5);
    this_thread::sleep_for(1s);
    send(6);
    send.close();

    sleep(20);
}