Dart Example with stream

input-stream.dart

import "dart:html";
import "dart:async";

void main() {
  final InputElement input = querySelector("input");

  final DivElement div = querySelector("div");

  final validatorEmailFormatter =
      new StreamTransformer.fromHandlers(handleData: (inputValue, sink) {
    if (inputValue.contains("@")) {
      sink.add(inputValue);
    } else {
      sink.addError("Enter a valid emial!");
    }
  });

  final validatorNotGmailAddress =
      new StreamTransformer.fromHandlers(handleData: (inputValue, sink) {
    if (inputValue.contains("gmail.")) {
      sink.add(inputValue);
    } else {
      sink.addError("You must used gmail only !! 😡");
    }
  });

  input.onInput
      .map((dynamic event) => event.target.value)
      .transform(validatorEmailFormatter)
      .transform(validatorNotGmailAddress)
      .listen((input) {
    print("Email is valid!! \"$input\" ");
    div.innerHtml = "";
  },
          onDone: () => print("Done stream."),
          onError: (error) => div.innerHtml = error);
}

stream-sink-exmaple.dart

import "dart:async";

class Cake {}

class Order {
  String type;
  Order(this.type);
}

void main() {
  final controller = new StreamController();
  final order = new Order("banana");
  final order2 = new Order("chocolate");

  final baker =
      new StreamTransformer.fromHandlers(handleData: (cakeType, sink) {
    if (cakeType == "chocolate") {
      sink.add(new Cake());
    } else {
      sink.addError('I cant bake that type!!');
    }
  });

  controller.sink.add(order);
  controller.sink.add(order2);

  controller.stream
      .map((order) => order.type)
      .transform(baker)
      .listen((cake) => print("Heres your cake $cake"))
      .onError((error) => print(error));
    
    
}