Language/Types/Interface_Types/subtype_t17.dart

// 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 GenericType<T> is a subtype of GenericType<S> where
 * T is subtype of S (T and S are non-generic interfaces and/or Dynamic).
 * @author iefremov
 */
import "../../../Utils/expect.dart";

class I {}
class J implements I {}
class K implements J {}

class Z<T> {
  Z() {}
}

main() {
  Expect.isTrue(new List<String>.empty() is List);
  Expect.isFalse(new List.empty() is List<String>);
  Expect.isTrue(new List<String>.empty() is List<Object>);
  Expect.isTrue(new List<String>.empty() is List<Object>);
  Expect.isTrue(new List<int>.empty() is List<num>);
  Expect.isTrue(new List<int>.empty() is List);
  Expect.isTrue(new List<int>.empty() is List<Object>);
  Expect.isTrue(new List<double>.empty() is List<Object>);
  Expect.isTrue(new List<double>.empty() is List);
  Expect.isTrue(new List<double>.empty() is List<num>);
  Expect.isTrue(new List<J>.empty() is List);
  Expect.isTrue(new List<J>.empty() is List<Object>);
  Expect.isTrue(new List<J>.empty() is List<I>);
  Expect.isTrue(new List<K>.empty() is List<I>);
  Expect.isTrue(new List<K>.empty() is List<J>);

  Expect.isTrue(new Z<String>() is Z);
  Expect.isFalse(new Z() is Z<String>);
  Expect.isTrue(new Z<String>() is Z<Object>);
  Expect.isTrue(new Z<String>() is Z<Object>);
  Expect.isTrue(new Z<int>() is Z<num>);
  Expect.isTrue(new Z<int>() is Z);
  Expect.isTrue(new Z<int>() is Z<Object>);
  Expect.isTrue(new Z<double>() is Z<Object>);
  Expect.isTrue(new Z<double>() is Z);
  Expect.isTrue(new Z<double>() is Z<num>);
  Expect.isTrue(new Z<J>() is Z);
  Expect.isTrue(new Z<J>() is Z<Object>);
  Expect.isTrue(new Z<J>() is Z<I>);
  Expect.isTrue(new Z<K>() is Z<I>);
  Expect.isTrue(new Z<K>() is Z<J>);
}