LanguageFeatures/Patterns/map_A04_t02.dart

// Copyright (c) 2022, 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
/// mapPattern        ::= typeArguments? '{' mapPatternEntries? '}'
/// mapPatternEntries ::= mapPatternEntry ( ',' mapPatternEntry )* ','?
/// mapPatternEntry   ::= expression ':' pattern
///
/// A map pattern matches values that implement Map and accesses values by key
/// from it.
/// It is a compile-time error if:
/// - typeArguments is present and there are more or fewer than two type
///   arguments.
/// - Any of the entry key expressions are not constant expressions.
/// - Any two keys in the map are identical.
/// - Any two record keys which both have primitive equality are equal.
///
/// @description Check that it is no compile-time error if any two keys in the
/// map are equal according to their == operator, but not identical
/// @author sgrekhov22@gmail.com

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

class C {
  final int x;
  const C(this.x);

  @override
  bool operator ==(Object other) {
    if (other is C) {
      return this.x == other.x;
    }
    return false;
  }

  @override
  int get hashCode => x;
}

const c1 = C(1);
const c2 = C(2);
const c3 = C(3);

String test1(Map map) {
  return switch (map) {
    {c1: var a, c2: final b} => "a=$a, b=$b",
    _ => "default"
  };
}

String test2(Map map) {
  switch (map) {
    case {c1: var a, c2: final b}:
      return "a=$a, b=$b";
    default:
      return "default";
  }
}

String test3(Map map) {
  if (map case {c1: var a, c2: final b}) {
    return "a=$a, b=$b";
  }
  return "default";
}

main() {
  Expect.throws(() {
    var {c1: a, c2: b} = {3.14: 1};
  });
  Expect.throws(() {
    var {c1: a, c2: b} = {3.14: 1, 3.14: 2, 3.14: 3};
  });
  var {c1: a1, c2: b1} = {c1: 1, c2: 2};
  Expect.equals(1, a1);
  Expect.equals(2, b1);
  final {c1: int a2, c2: int b2} = {c1: 1, c2: 2};
  Expect.equals(1, a2);
  Expect.equals(2, b2);

  Expect.equals("a=1, b=2", test1({c1: 1, c2: 2}));
  Expect.equals("default", test1({c1: 1}));
  Expect.equals("a=1, b=2", test1({c1: 1, c2: 2, c3: 3}));
  Expect.equals("a=1, b=2", test2({c1: 1, c2: 2}));
  Expect.equals("default", test2({c1: 1}));
  Expect.equals("a=1, b=2", test2({c1: 1, c2: 2, c3: 3}));
  Expect.equals("a=1, b=2", test3({c1: 1, c2: 2}));
  Expect.equals("default", test3({c1: 1}));
  Expect.equals("a=1, b=2", test3({c1: 1, c2: 2, c3: 3}));
}