Robert Nystrom
fc1b1ecc71
Change-Id: Idbcc965a27e9ffeedf5e0a1068b019de4193070f Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127745 Commit-Queue: Bob Nystrom <rnystrom@google.com> Reviewed-by: Alexander Thomas <athom@google.com>
33 lines
760 B
Dart
33 lines
760 B
Dart
// Copyright (c) 2015, 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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// Evaluation of an if-null expression e of the form e1 ?? e2 is equivalent to
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// the evaluation of the expression ((x) => x == null ? e2 : x)(e1).
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//
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// Therefore, e1 should be evaluated first; if it is non-null, e2 should not
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// be evaluated.
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import "package:expect/expect.dart";
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bad() {
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throw new Exception();
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}
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bool firstExecuted = false;
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first() {
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firstExecuted = true;
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return null;
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}
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second() {
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Expect.isTrue(firstExecuted);
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return 2;
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}
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main() {
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Expect.equals(1, 1 ?? bad());
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Expect.equals(2, first() ?? second());
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}
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