Robert Nystrom
dbaf041ae4
Change-Id: Ia3238c1781422ec5eb7a219a5cf8af645a4c5876 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409000 Commit-Queue: Bob Nystrom <rnystrom@google.com> Reviewed-by: Lasse Nielsen <lrn@google.com> Auto-Submit: Bob Nystrom <rnystrom@google.com>
92 lines
2.5 KiB
Dart
92 lines
2.5 KiB
Dart
// Copyright (c) 2022, 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 "package:expect/expect.dart";
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main() {
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switchSingleCase();
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ifCase();
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sharedCaseUseInBody();
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sharedCaseOnlyGuards();
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}
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/// Guard and body use same variables when cases are not shared.
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void switchSingleCase() {
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_closures.clear();
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switch (['one', 'two']) {
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case [var a, var b] when _capture(() => a) && _capture(() => b):
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Expect.equals('one two', _runClosures());
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Expect.equals('one', a);
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Expect.equals('two', b);
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a = 'after';
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b = 'then';
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Expect.equals('after', a);
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Expect.equals('then', b);
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// Guard closures see update.
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Expect.equals('after then', _runClosures());
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}
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}
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/// Guard and body use same variables in if-case statements.
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void ifCase() {
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_closures.clear();
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if (['one', 'two'] case [
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var a,
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var b,
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] when _capture(() => a) && _capture(() => b)) {
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Expect.equals('one two', _runClosures());
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Expect.equals('one', a);
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Expect.equals('two', b);
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a = 'after';
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b = 'then';
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Expect.equals('after', a);
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Expect.equals('then', b);
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// Guard closures see update.
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Expect.equals('after then', _runClosures());
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}
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}
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/// Guards and body get separate variable when cases are shared.
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void sharedCaseUseInBody() {
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_closures.clear();
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switch (['one', 'two', 'three']) {
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case [var a, _, _] when _capture(() => a, false):
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case [_, var a, _] when _capture(() => a, false):
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case [_, _, var a] when _capture(() => a, true):
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Expect.equals('three', a);
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Expect.equals('one two three', _runClosures());
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a = 'after';
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Expect.equals('after', a);
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// Guard closures are unaffected.
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Expect.equals('one two three', _runClosures());
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}
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}
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/// Guards each have their own separate variables even when the variable isn't
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/// used in the body.
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void sharedCaseOnlyGuards() {
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_closures.clear();
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switch (['one', 'two', 'three']) {
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case [var a, _, _] when _capture(() => a, false):
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case [_, var a, _] when _capture(() => a, false):
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case [_, _, var a] when _capture(() => a, true):
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Expect.equals('one two three', _runClosures());
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}
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}
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final _closures = <Object Function()>[];
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bool _capture(Object Function() closure, [bool result = true]) {
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_closures.add(closure);
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return result;
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}
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String _runClosures() => _closures.map((closure) => closure()).join(' ');
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