Dart Range Extensions

dartrange.dart

void main() {
  // 2,3,4,5,6,7,8,9,10
  for (int i in 2.to(10)) {
    print(i);
  }

  // 2,3,4,5,6,7,8,9
  for (int i in 2.until(10)) {
    print(i);
  }

  // 2,1,0,-1,-2,-3,-4,-5,-6,-7
  for (int i in 2.to(-7)) {
    print(i);
  }

  // 2,1,0,-1,-2,-3,-4,-5,-6
  for (int i in 2.until(-7)) {
    print(i);
  }
}

extension Range on num {
  List<num> until(num endPoint) {
    var exclusive = to(endPoint);
    exclusive.removeLast();
    return exclusive;
  }

  List<num> to(num endPoint) {
    var numbers = <num>[];
    if (endPoint > this) {
      for (int i = this; i <= endPoint; i++) {
        numbers.add(i);
      }
    } else {
      for (int i = this; i >= endPoint; i--) {
        numbers.add(i);
      }
    }
    return numbers;
  }
}