태스크트리 신호등

enum class Light
{
    Off    = 0,
    Red    = 1 << 0,
    Yellow = 1 << 1,
    Green  = 1 << 2,
};

Q_DECLARE_FLAGS(Lights, Light)
Q_DECLARE_OPERATORS_FOR_FLAGS(Lights)

class GlueInterface final : public QObject
{
    Q_OBJECT

public:
    // operational logic -> GUI
    void setLights(Lights lights) { emit lightsChanged(lights); }

    // GUI -> operational logic
    void smash() { emit smashed(); }
    void repair() { emit repaired(); }

signals:
    void lightsChanged(Lights lights);

    void smashed();
    void repaired();
};

ExecutableItem recipe(GlueInterface &iface)
{
    return Forever {
        Group { // "working" state
            stopOnSuccess,
            parallel,
            signalAwaiterTask(&iface, &GlueInterface::smashed), // transitions to the "broken" state
            Forever {
                switchLightsTask(&iface, Light::Red, 3s), // "red" state
                switchLightsTask(&iface, Light::Red | Light::Yellow, 1s), // "redGoingGreen" state
                switchLightsTask(&iface, Light::Green, 3s), // "green" state
                switchLightsTask(&iface, Light::Yellow, 1s), // "greenGoingRed" state
            }
        },
        Group { // "broken" state
            stopOnSuccess,
            parallel,
            signalAwaiterTask(&iface, &GlueInterface::repaired), // transitions to the "working" state
            Forever {
                switchLightsTask(&iface, Light::Yellow, 1s), // "blinking" state
                switchLightsTask(&iface, Light::Off, 1s), // "unblinking" state
            }
        }
    };
}

static Group switchLightsTask(GlueInterface *iface, Lights lights, const milliseconds &timeout)
{
    return {
        onGroupSetup([iface, lights] { iface->setLights(lights); }),
        timeoutTask(timeout, DoneResult::Success)
    };
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    GlueInterface iface;
    QTaskTree taskTree({recipe(iface)});
    TrafficLight widget(iface);

    widget.show();
    taskTree.start();

    return app.exec();
}