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ed3824a220
It's a badly designed class, but this change makes it slightly better. (We should consider moving it to package:collection and removing it from the platform libraries. Eventually.) The changes decouples the public `DoubleLinkedQueueEntry` class from the actual queue implementation classes, avoiding the latter having to share a generic `_Link<DoubleLinkedQueueEntry>` interface which would force them to do otherwise unnecessary casts. The public class should have been abstract, but isn't. It's mainly used as the API of the entries exposed by DoubleLinkedQueue, but it can also be used by itself to build double-linked lists that are not part of a Queue, and the class can be extended. If anyone does either, it should keep working, so it needs to be a concrete, self-contained class with a generative constructor. That class is moved to dart:_internal to avoid its private implementation fields from interfering with the queue implementation classes, which have similar fields, but can now have them at different types. That's a hack, but it works. The internal implementation of the DoubleLinkedQueue and its entries are updated to better follow current programming idioms, and avoids having fields on classes which don't need them. Also fixes #27920 (`clear`ing a list now detaches each entry from the list so later `.contains` won't give the wrong answer). And moves queue tests from tests/corelib to tests/lib/collection, since Queue isn't exposed by `dart:core`. BUG= https://github.com/dart-lang/sdk/issues/27920 Change-Id: Ia3bb340a75886de160cc0e449947e8e7ee587061 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/211265 Commit-Queue: Lasse R.H. Nielsen <lrn@google.com> Reviewed-by: Nate Bosch <nbosch@google.com>
20 lines
532 B
Dart
20 lines
532 B
Dart
// Copyright (c) 2012, 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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library queue.last.test;
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import "package:expect/expect.dart";
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import 'dart:collection' show Queue;
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main() {
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Queue<int> queue1 = new Queue<int>();
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queue1
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..add(11)
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..add(12)
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..add(13);
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Queue queue2 = new Queue();
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Expect.equals(13, queue1.last);
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Expect.throwsStateError(() => queue2.last);
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}
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