play with dart 1

playground_1.dart

import 'dart:async';


class Range {
  final StreamController _controller = StreamController();
  
  final int from;
  final int to;
  int seconds;
  
  Stream<dynamic> get stream => _controller.stream.asBroadcastStream();
  
  Range({ this.from = 1, this.to = 0 }) : assert(from != null), assert(to != null) {
    genNormalRange(); 
  }
  
  Range.periodic({ this.seconds, this.from = 1, this.to = 0 }): assert(wait != null), assert(from != null), assert(to != null) { 
    genPeriodicRange(); 
  }
  
  Future genPeriodicRange() async {
    for(var i = from; i <= to; i++) {
      await wait(Duration(seconds: seconds));
       _controller.sink.add(i);
    }
    _controller.close();
  }
  
  void genNormalRange() {
     for(var i = from; i <= to; i++) {
       _controller.sink.add(i);
    }
    _controller.close();
  }
}


Future wait(Duration duration) {
  Completer completer = Completer();
  Timer(duration, completer.complete);
  return completer.future;
}

void main() {
  final periodicRange$ = Range.periodic(seconds: 1, to: 10).stream;
  
  periodicRange$.listen((i) => print(i));
  periodicRange$.where((i) => i % 2 == 0).listen((i) => print(i));
  periodicRange$.where((i) => i % 2 != 0).listen((i) => print(i));

}