Bob Nystrom
14011f47e3
They're back from the grave, and ready to party! Change-Id: I088134a9be7ecabf1fbf751c015a656a15cabff9 Reviewed-on: https://dart-review.googlesource.com/12821 Commit-Queue: Bob Nystrom <rnystrom@google.com> Reviewed-by: William Hesse <whesse@google.com>
58 lines
2.0 KiB
Dart
58 lines
2.0 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)
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: b = v,
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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)
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: c = v,
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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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noMethod(e) => e is NoSuchMethodError;
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main() {
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// Make sure the "none" test fails if "??" is not implemented. This makes
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// status files easier to maintain.
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var _ = null ?? null;
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Expect.equals(1, 1 ?? 2); //# 01: ok
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Expect.equals(1, 1 ?? null); //# 02: ok
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Expect.equals(2, null ?? 2); //# 03: ok
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Expect.equals(null, null ?? null); //# 04: ok
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Expect.equals('B', (new B('B') ?? new C('C')).a); //# 05: ok
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Expect.equals('B', (new B('B') ?? new C('C')).b); //# 06: static type warning
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Expect.throws(() => (new B('B') ?? new C('C')).c, noMethod); //# 07: static type warning
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Expect.equals('B', (new B('B') ?? nullC()).a); //# 08: ok
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Expect.equals('B', (new B('B') ?? nullC()).b); //# 09: static type warning
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Expect.throws(() => (new B('B') ?? nullC()).c, noMethod); //# 10: static type warning
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Expect.equals('C', (nullB() ?? new C('C')).a); //# 11: ok
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Expect.throws(() => (nullB() ?? new C('C')).b, noMethod); //# 12: static type warning
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Expect.equals('C', (nullB() ?? new C('C')).c); //# 13: static type warning
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Expect.throws(() => (nullB() ?? nullC()).a, noMethod); //# 14: ok
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Expect.throws(() => (nullB() ?? nullC()).b, noMethod); //# 15: static type warning
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Expect.throws(() => (nullB() ?? nullC()).c, noMethod); //# 16: static type warning
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}
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