Language/15_Types/4_Interface_Types_A08_t03.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 S is a direct supertype of T.
 * << is a partial order on types. T is a subtype of S, written T <: S, iff [⊥/Dynamic]T << S.
 * A 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 if
 * t1 <: t2 or 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
 * @reviewer rodionov
 */

import "../../Utils/dynamic_check.dart";

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 B f1(int i, B b, Map<int, num> m, var x, [var ox, B ob, 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, D ob, List<num> ol, bool obool]) {}
D f02(int i, D b, Map<int, int> m, func x, [func ox, D ob, List<int> ol, bool obool]) {}
C f03(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob, List ol, Object obool]) {}
A f04(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob, List ol, Object obool]) {}
A f05(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob, List ol, Object obool, var more1]) {}
A f06(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob, List ol, Object obool, var more1, int more2]) {}

C f11(num i, A b, Map<Object, Object> m, var x) {}
C f12(num i, A b, Map<Object, Object> m, var x, [var ox]) {}
C f13(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob]) {}
C f14(num i, A b, Map<Object, Object> m, var x, [var ox, A2 ob, List ol]) {}

B f21(int i, B b, Map<int, num> m, var x, [var ox, B ob, List<num> ol, bool obool]) {}
B f22(int i, B b, Map<int, num> m, var x, [var ox, B ob, List<num> ol, bool obool]) {}
B f23(int i, B b, Map<int, num> m, var x, [var ox, B ob, List<num> ol, bool obool]) {}
B f24(int i, B b, Map<int, num> m, var x, [var ox, B ob, List<num> ol, bool obool]) {}

main() {
  //functions on the right are subtypes of f1
  f1 fvar = f01;
  fvar = f02;
  fvar = f03;
  fvar = f04;
  fvar = f05;
  fvar = f06;

  //functions on the right are supertypes of f1
  checkTypeError(() {
    fvar = f11;
  });
  checkTypeError(() {
    fvar = f12;
  });
  checkTypeError(() {
    fvar = f13;
  });
  checkTypeError(() {
    fvar = f14;
  });

  //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;
}