// Create a taskflow graph with three static tasks and one subflow task.

tf::Taskflow taskflow("visitor");

tf::Executor executor;

auto A = taskflow.emplace([]() { std::cout << "TaskA\n"; });

auto B = taskflow.emplace([](tf::Subflow& subflow) {

std::cout << "TaskB is spawning B1, B2, and B3 ...\n";

auto B1 = subflow.emplace([&](){ printf(" Subtask B1\n"); }).name("B1");

auto B2 = subflow.emplace([&](){ printf(" Subtask B2\n"); }).name("B2");

auto B3 = subflow.emplace([&](){ printf(" Subtask B3\n"); }).name("B3");

B1.precede(B3);

B2.precede(B3);

subflow.retain(true); // retains the subflow

});

auto C = taskflow.emplace([] () { std::cout << "TaskC\n"; });

auto D = taskflow.emplace([] () { std::cout << "TaskD\n"; });

A.name("A");

B.name("B");

C.name("C");

D.name("D");

A.precede(B); // B runs after A

A.precede(C); // C runs after A

B.precede(D); // D runs after B

C.precede(D); // D runs after C

executor.run(taskflow).wait();

// examine the graph

taskflow.dump(std::cout);

// traverse all tasks in the taskflow

taskflow.for_each_task([](tf::Task task){

std::cout << "task " << task.name() << " [type=" << tf::to_string(task.type()) << "]\n";

// traverse it's successor

task.for_each_successor([](tf::Task successor) {

std::cout << " -> successor task " << successor.name() << '\n';

});

// traverse it's predecessor

task.for_each_predecessor([](tf::Task predecessor) {

std::cout << " <- predecessor task " << predecessor.name() << '\n';

});

// traverse the subflow (in our example, task B)

task.for_each_subflow_task([](tf::Task stask){

std::cout << " subflow task " << stask.name() << '\n';

// traverse it's successor

stask.for_each_successor([](tf::Task successor) {

std::cout << " -> successor task " << successor.name() << '\n';

});

// traverse it's predecessor

stask.for_each_predecessor([](tf::Task predecessor) {

std::cout << " <- predecessor task " << predecessor.name() << '\n';

});

});

});

return 0;