Stephen Adams
048c7b036b
Dart does not officially support browsers before the introduction of WeakRef and FinalizationRegistry but there are users of Dart that have a few customers still using these browsers. As a result, both ACX and Flutter have ad-hoc polyfills for these classes. Adding the polyfill in js_runtime will allow the other polyfills to be removed. The polyfill is as small as possible (omitting checks, avoiding extra Dart classes, detecting as late as possible), so it should be a net code size improvement of a few bytes for ACX and Flutter use cases. The polyfill leaks memory by retaining the weak reference target and never calls the finalization callbacks. This is permitted behaviour. Change-Id: I4f0d08ee6322dab26728d95ca8c24a7fd59b3314 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/333304 Reviewed-by: Sigmund Cherem <sigmund@google.com> Commit-Queue: Stephen Adams <sra@google.com>
67 lines
2.1 KiB
Dart
67 lines
2.1 KiB
Dart
// Copyright (c) 2023, 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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// Basic tests for the dart2js-only polyfill for WeakReference and Finalizer API
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// for the dart2js backends.
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import 'package:expect/minitest.dart';
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import 'dart:js_interop_unsafe';
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import 'dart:js_interop';
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class Foo {
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int close() {
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return 42; // no-op, dropped return value.
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}
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}
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void callback(Foo f) {
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f.close();
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}
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main() {
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// Remove global bindings to simulate a JavaScript environment before these
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// bindings were added.
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globalContext.delete('WeakRef'.toJS);
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globalContext.delete('FinalizationRegistry'.toJS);
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test('weak reference', () {
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var list = ["foo"];
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var weakRef = WeakReference<List<String>>(list);
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expect(weakRef.target, equals(list));
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// JavaScript API throws when the representation of target is not 'object'
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// in the compiled JavaScript. The polyfill does not check argument
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// types. This verifies that the polyfill is being used.
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WeakReference<String>("foo");
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WeakReference<int>(1);
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});
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test('finalizer', () {
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var finalizer = Finalizer<Foo>(callback);
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var list = ["foo"];
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var foo = Foo();
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// Should not cause errors to attach or detach
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finalizer.attach(list, foo);
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finalizer.attach(list, foo, detach: list);
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finalizer.detach(list);
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// Should not cause errors to use a different detach token
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var detachList = [1, 2, 3];
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finalizer.attach(list, foo, detach: detachList);
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finalizer.detach(detachList);
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// JavaScript API returns false when unknown target detached.
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// Should not cause an error to detach unknown token.
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var unknownList = [2, 4, 6];
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finalizer.detach(unknownList);
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// JavaScript API throws when target and detach token are not objects. The
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// polyfill does not check argument types. This verifies the polyfill is
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// being used.
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finalizer.attach("token string value", foo);
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finalizer.detach("detach string value");
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});
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}
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