blob: 2674f9551d8900db28d3be0a296630bca11dec17 [file] [log] [blame]
// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:async';
import 'package:expect/expect.dart';
import 'package:async_helper/async_helper.dart';
typedef Future<Null> Task();
class ForeignFuture implements Future<Null> {
ForeignFuture(List<Task> tasks) {
tasks.forEach(_addTask);
}
Future<Null> _future;
void _addTask(Task task) {
_future = (_future == null) ? task() : _future.then((_) => task());
}
Future<S> then<S>(FutureOr<S> onValue(Null _), {Function onError}) {
assert(_future != null);
return _future.then((_) {
_future = null;
return onValue(null);
}, onError: (error, trace) {
_future = null;
if (onError != null) {
onError(error, trace);
}
});
}
Stream<Null> asStream() {
return new Stream.fromFuture(this);
}
Future<Null> catchError(onError, {bool test(Object error)}) {
print('Unimplemented catchError');
return null;
}
Future<Null> timeout(Duration timeLimit, {onTimeout()}) {
print('Unimplemented timeout');
return null;
}
Future<Null> whenComplete(action()) {
print('Unimplemented whenComplete');
return null;
}
}
var r1;
Future<Null> hello() async {
r1 = 'hello';
throw new Exception('error');
}
Future<String> world() async {
try {
await new ForeignFuture([hello]);
} catch (e) {}
return 'world';
}
void main() {
asyncStart();
() async {
var r2 = await world();
Expect.equals('hello', r1);
Expect.equals('world', r2);
asyncEnd();
}();
}