Language/Types/Interface_Types/subtype_t23.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 and S are simple functions.
/// @author iefremov

import "../../../Utils/expect.dart";

class I0 {}
class I1 extends I0 {}
class I2 extends I1 {}
class I3 extends I2 {}
class I4 extends I2 {}

class G<T> {}

typedef t1();
typedef void t1_1(); // void <: Dynamic
typedef G<List<t1>> t1_2();

typedef I2 t2(I2 i, [I2 j]);
typedef I0 t2_1(I0 i, [I0 j]);
typedef I4 t2_2(I4 i, [I4 j]);
typedef I4 t2_3(I0 i, [I4 j]);
typedef I0 t2_4(I4 i, [I0 j]);

typedef t1 t3(t1 f1, [t1 f2]);
typedef t1_1 t3_1(t1_1 f1, [t1_1 f2]);
typedef t1_2 t3_2(t1_2 f1, [t1_2 f2]);

main() {
  Expect.isTrue(new List<t1>.empty() is List<t1>);
  Expect.runtimeIsType<List<t1>>(new List<t1>.empty());
  Expect.isTrue(new List<t1_1>.empty() is List<t1>);
  Expect.runtimeIsType<List<t1>>(new List<t1_1>.empty());
  Expect.isTrue(new List<t1_2>.empty() is List<t1>);
  Expect.runtimeIsType<List<t1>>(new List<t1_2>.empty());

  Expect.isTrue(new List<t2>.empty() is List<t2>);
  Expect.isFalse(new List<t2_1>.empty() is List<t2>);
  Expect.isFalse(new List<t2_2>.empty() is List<t2>);
  Expect.isFalse(new List<t2_3>.empty() is List<t2>);
  Expect.isFalse(new List<t2_4>.empty() is List<t2>);
  Expect.runtimeIsType<List<t2>>(new List<t2>.empty());
  Expect.runtimeIsNotType<List<t2>>(new List<t2_1>.empty());
  Expect.runtimeIsNotType<List<t2>>(new List<t2_2>.empty());
  Expect.runtimeIsNotType<List<t2>>(new List<t2_3>.empty());
  Expect.runtimeIsNotType<List<t2>>(new List<t2_4>.empty());

  Expect.isTrue(new List<t3>.empty() is List<t3>);
  Expect.isTrue(new List<t3_1>.empty() is List<t3>);
  Expect.isFalse(new List<t3_2>.empty() is List<t3>);
  Expect.runtimeIsType<List<t3>>(new List<t3>.empty());
  Expect.runtimeIsType<List<t3>>(new List<t3_1>.empty());
  Expect.runtimeIsNotType<List<t3>>(new List<t3_2>.empty());
}