| // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| // Verify semantics of the ?. operator when it is used to invoke a method. |
| |
| // SharedOptions=--enable-null-aware-operators |
| |
| import "package:expect/expect.dart"; |
| import "conditional_access_helper.dart" as h; |
| |
| bad() { |
| Expect.fail('Should not be executed'); |
| } |
| |
| noMethod(e) => e is NoSuchMethodError; |
| |
| class B {} |
| |
| class C extends B { |
| f(callback()) => callback(); |
| int g(int callback()) => callback(); |
| static void staticMethod() {} |
| } |
| |
| C nullC() => null; |
| |
| main() { |
| // Make sure the "none" test fails if method invocation using "?." is not |
| // implemented. This makes status files easier to maintain. |
| nullC()?.f(null); |
| |
| // o?.m(...) is equivalent to ((x) => x == null ? null : x.m(...))(o). |
| Expect.equals(null, nullC()?.f(bad())); /// 01: ok |
| Expect.equals(1, new C()?.f(() => 1)); /// 02: ok |
| |
| // The static type of o?.m(...) is the same as the static type of |
| // o.m(...). |
| { int i = nullC()?.g(bad()); Expect.equals(null, i); } /// 03: ok |
| { int i = new C()?.g(() => 1); Expect.equals(1, i); } /// 04: ok |
| { String s = nullC()?.g(bad()); Expect.equals(null, s); } /// 05: static type warning |
| { String s = new C()?.g(() => null); Expect.equals(null, s); } /// 06: static type warning |
| |
| // Let T be the static type of o and let y be a fresh variable of type T. |
| // Exactly the same static warnings that would be caused by y.m(...) are also |
| // generated in the case of o?.m(...). |
| { B b = new C(); Expect.equals(1, b?.f(() => 1)); } /// 07: static type warning |
| { int i = 1; Expect.equals(null, nullC()?.f(i)); } /// 08: static type warning |
| |
| // Consequently, '?.' cannot be used to invoke static methods of classes. |
| Expect.throws(() => C?.staticMethod(), noMethod); /// 09: static type warning |
| Expect.throws(() => h.C?.staticMethod(), noMethod); /// 10: static type warning |
| |
| // Nor can it be used to access toplevel functions in libraries imported via |
| // prefix. |
| h?.topLevelFunction(); /// 11: compile-time error |
| |
| // However, '?.' can be used to access the toString method on the class Type. |
| Expect.equals(C?.toString(), (C).toString()); /// 12: ok |
| Expect.equals(h.C?.toString(), (h.C).toString()); /// 13: ok |
| } |