How can I break from dart generator based on some condition?

fn sync*(...){
  yield 1;
  yield 2;
  if(someCondition()) //cancel/break the generator
  yield 3;
  if(someCondition2()) //cancel/break the generator
  yield 4;
  if(someCondition4()) //cancel/break the generator
  yield 5;
}

>Solution :

Simply return from your generator when you want it to stop generating new values:

Iterable<int> fn(bool flag) sync* {
  yield 1;
  yield 2;
  if (flag) {
    return;
  }
  yield 3;
}

void main() {
  print(fn(true).toList()); // Prints: [1, 2]
  print(fn(false).toList()); // Prints: [1, 2, 3]
}