| // Copyright (c) 2011, 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. |
| |
| /** |
| * @assertion A type T is more specific than a type S, written T << S, if one |
| * of the following conditions is met: |
| * • T is S. |
| * • T is ⊥ |
| * • S is dynamic. |
| * • S is a direct supertype of T. |
| * • T is a type parameter and S is the upper bound of T. |
| * • T is a type parameter and S is Object. |
| * • T is of the form I<T1, ..., Tn > and S is of the form I <S1, ..., Sn> |
| * and Ti << Si 1 <= i <= n. |
| * • T and S are both function types, and T << S under the rules of section |
| * (Types/Function Types). |
| * • T is a function type and S is Function. |
| * • T << U and U << S. |
| * << is a partial order on types. T is a subtype of S, written T <: S, iff |
| * [⊥/Dynamic]T << S. |
| * . . . |
| * An interface type T may be assigned to a type S, written T <=> S, if either |
| * T <: S or S <: T. |
| * @description Checks that a function type t1 is assignable (no static |
| * warnings) to a function type t2 only if t1 <: t2 where t1 and t2 are |
| * quite complex: non-dynamic return type plus a bunch of formal and optional |
| * parameters. Subtypes of a function type described according to |
| * (Types/Function Types). |
| * @author iefremov |
| */ |
| |
| class A {} |
| class A1 {} |
| class A2 {} |
| class B implements A, A1, A2 {} |
| class C implements B {} |
| class D implements C {} |
| |
| typedef B func(Object o); |
| typedef A f1(int i, D d, Map<int, num> m, var x, |
| [var ox, D od, List<num> ol, bool obool]); |
| |
| //fewer optional parameters |
| typedef B f1_1(int i, B b, Map<int, num> m, var x, |
| [var ox, B ob, List<num> ol]); |
| typedef B f1_2(int i, B b, Map<int, num> m, var x, [var ox, B ob]); |
| typedef B f1_3(int i, B b, Map<int, num> m, var x, [var ox]); |
| typedef B f1_4(int i, B b, Map<int, num> m, var x); |
| |
| B f01(int i, B b, Map<int, num> m, var x, |
| [var ox, B? ob, List<num>? ol, bool? obool]) => new B(); |
| D f02(int i, D b, Map<num, num> m, var x, |
| [var ox, D? ob, List<Object>? ol, bool? obool]) => new D(); |
| C f03(num i, A b, Map<Object, Object> m, var x, |
| [var ox, A2? ob, List? ol, Object? obool]) => new C(); |
| A f04(num i, A b, Map<Object, Object> m, var x, |
| [var ox, A2? ob, List? ol, Object? obool]) => new A(); |
| A f05(num i, A b, Map<Object, Object> m, var x, |
| [var ox, A2? ob, List? ol, Object? obool, var more1]) => new A(); |
| A f06(num i, A b, Map<Object, Object> m, var x, |
| [var ox, A2? ob, List? ol, Object? obool, var more1, int? more2]) => new A(); |
| |
| B f21(int i, B b, Map<int, num> m, var x, |
| [var ox, B? ob, List<num>? ol, bool? obool]) => new B(); |
| B f22(int i, B b, Map<int, num> m, var x, |
| [var ox, B? ob, List<num>? ol, bool? obool]) => new B(); |
| B f23(int i, B b, Map<int, num> m, var x, |
| [var ox, B? ob, List<num>? ol, bool? obool]) => new B(); |
| B f24(int i, B b, Map<int, num> m, var x, |
| [var ox, B? ob, List<num>? ol, bool? obool]) => new B(); |
| |
| main() { |
| //functions on the right are subtypes of f1 |
| f1 fvar = f01; |
| fvar = f02; |
| fvar = f03; |
| fvar = f04; |
| fvar = f05; |
| fvar = f06; |
| |
| //function on the right is a subtype of f1_* |
| f1_1 fvar_1 = f21; |
| f1_2 fvar_2 = f22; |
| f1_3 fvar_3 = f23; |
| f1_4 fvar_4 = f24; |
| } |