Lasse R.H. Nielsen
659978fcb3
A little extra clean-up in related files. Change-Id: I1d0d809d1ab4d756470e3a292e8e070ef31304af Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402660 Commit-Queue: Lasse Nielsen <lrn@google.com> Reviewed-by: Bob Nystrom <rnystrom@google.com> Reviewed-by: Nate Bosch <nbosch@google.com>
48 lines
1.2 KiB
Dart
48 lines
1.2 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'dart:async';
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import 'package:expect/async_helper.dart';
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import 'package:expect/expect.dart';
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import 'package:expect/variations.dart' show checkedParameters;
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class A {
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const A();
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}
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class B extends A {
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const B();
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}
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class C extends B {
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const C();
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}
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void main() {
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if (checkedParameters) {
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Stream<A> stream = Stream<B>.fromIterable([B()]);
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A aFunc() => const A();
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// `firstWhere` does not dynamically allow you to return
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// instances that are not subtypes of the stream element type.
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Expect.throws<TypeError>(() {
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// `aFunc` is not a `B Function()`.
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stream.firstWhere((x) => false, orElse: aFunc);
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});
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}
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// Returning a subtype is fine.
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{
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asyncStart();
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C cFunc() => const C();
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Stream<B> stream = Stream<B>.fromIterable([B()]);
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// `firstWhere` does allow you to return instances of subtypes the
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// stream element type.
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stream.firstWhere((x) => false, orElse: cFunc).then((value) {
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Expect.identical(const C(), value);
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asyncEnd();
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});
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}
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}
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