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b9b30b5883
This doesn't comprehensively cover everything we should test around pattern variable scopes, but I wanted to cover most of the tricky behavior around variables in cases that share a body, along with some other edge cases that I thought of while speccing that out. Change-Id: I64fff7b4a9a30b00801fbf37b52f07799ef0fd35 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/268370 Commit-Queue: Bob Nystrom <rnystrom@google.com> Reviewed-by: Paul Berry <paulberry@google.com> Reviewed-by: Kallen Tu <kallentu@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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// SharedOptions=--enable-experiment=patterns
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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']
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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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/// 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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