Robert Nystrom
7134a451f3
A lot of files in this one, but nothing interesting in any of the tests. Change-Id: I69c705bfd2c2b2f9711b393e4ac78c357336e1a7 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/407660 Commit-Queue: Lasse Nielsen <lrn@google.com> Reviewed-by: Lasse Nielsen <lrn@google.com> Auto-Submit: Bob Nystrom <rnystrom@google.com>
50 lines
1.7 KiB
Dart
50 lines
1.7 KiB
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). The
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// static type of e is the least upper bound of the static type of e1 and the
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// static type of e2.
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import "package:expect/expect.dart";
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class A {
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final String a;
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A(this.a);
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}
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class B extends A {
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B(String v) : b = v, super(v);
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final String b;
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}
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class C extends A {
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C(String v) : c = v, super(v);
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final String c;
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}
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B? nullB() => null;
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C? nullC() => null;
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main() {
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var one = 1 as int?;
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var b = B('B') as B?;
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Expect.equals(1, one ?? 2);
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Expect.equals(1, one ?? null);
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Expect.equals(2, null ?? 2);
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Expect.equals(null, null ?? null);
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Expect.equals('B', (b ?? new C('C')).a);
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Expect.equals('B', ((b ?? new C('C')) as dynamic).b);
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Expect.throwsNoSuchMethodError(() => ((b ?? new C('C')) as dynamic).c);
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Expect.equals('B', (b ?? nullC())?.a);
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Expect.equals('B', ((b ?? nullC()) as dynamic).b);
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Expect.throwsNoSuchMethodError(() => ((b ?? nullC()) as dynamic).c);
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Expect.equals('C', (nullB() ?? new C('C')).a);
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Expect.throwsNoSuchMethodError(() => ((nullB() ?? new C('C')) as dynamic).b);
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Expect.equals('C', ((nullB() ?? new C('C')) as dynamic).c);
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Expect.throwsNoSuchMethodError(() => ((nullB() ?? nullC()) as dynamic).a);
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Expect.throwsNoSuchMethodError(() => ((nullB() ?? nullC()) as dynamic).b);
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Expect.throwsNoSuchMethodError(() => ((nullB() ?? nullC()) as dynamic).c);
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}
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