LanguageFeatures/Patterns/variable_A02_t04.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
/// variablePattern ::= ( 'var' | 'final' | 'final'? type )? identifier
///
/// A variable pattern binds the matched value to a new variable. These usually
/// occur as subpatterns of a destructuring pattern in order to capture a
/// destructured value.
/// ```dart
/// var (a, b) = (1, 2);
/// ```
/// Here, a and b are variable patterns and end up bound to 1 and 2,
/// respectively.
///
/// The pattern may have a type annotation in order to only match values of the
/// specified type. If the type annotation is omitted, the variable's type is
/// inferred and the pattern matches all values.
/// ```dart
/// switch (record) {
///   case (int x, String s):
///     print('First field is int $x and second is String $s.');
/// }
/// ```
/// @description Check that if the type annotation is specified then the
/// pattern matches values of the appropriate type only. Test list pattern
/// @author sgrekhov22@gmail.com

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

class C {
  @override
  String toString() => "C";
}

String test1(List l) {
  switch (l) {
    case ([int a, String b]):
      a.expectStaticType<Exactly<int>>();
      b.expectStaticType<Exactly<String>>();
      return "[<int>$a, <String>$b]";
    case ([int c, final int d]):
      c.expectStaticType<Exactly<int>>();
      d.expectStaticType<Exactly<int>>();
      return "[<int>$c, <int>$d]";
    case ([String e, bool f]):
      e.expectStaticType<Exactly<String>>();
      f.expectStaticType<Exactly<bool>>();
      return "[<String>$e, <bool>$f]";
    case ([int g, final h]):
      g.expectStaticType<Exactly<int>>();
      return "[<int>$g, final $h]";
    default:
      return "default";
  }
}

String test2(List l) {
  return switch (l) {
    ([int a, String b]) => "[<int>$a, <String>$b]",
    ([int c, final int d]) => "[<int>$c, <int>$d]",
    ([String e, bool f]) => "[<String>$e, <bool>$f]",
    ([int g, final h]) => "[<int>$g, final $h]",
    _ => "default"
  };
}

String test3(List l) {
  if (l case ([int a, String b])) {
    a.expectStaticType<Exactly<int>>();
    b.expectStaticType<Exactly<String>>();
    return "[<int>$a, <String>$b]";
  }
  if (l case ([int c, final int d])) {
    c.expectStaticType<Exactly<int>>();
    d.expectStaticType<Exactly<int>>();
    return "[<int>$c, <int>$d]";
  }
  if (l case ([String e, bool f])) {
    e.expectStaticType<Exactly<String>>();
    f.expectStaticType<Exactly<bool>>();
    return "[<String>$e, <bool>$f]";
  }
  if (l case ([int g, final h])) {
    g.expectStaticType<Exactly<int>>();
    return "[<int>$g, final $h]";
  } else {
    return "default";
  }
}

main() {
  Expect.equals("[<int>1, <String>x]", test1([ 1, "x"]));
  Expect.equals("[<int>42, <String>answer]", test1([42, "answer"]));
  Expect.equals("[<int>1, <int>2]", test1([1, 2]));
  Expect.equals("[<int>3, <int>4]", test1([3, 4]));
  Expect.equals("[<String>x, <bool>true]", test1(["x", true]));
  Expect.equals("[<String>y, <bool>false]", test1(["y", false]));
  Expect.equals("[<int>0, final false]", test1([0, false]));
  Expect.equals("[<int>1, final C]", test1([1, C()]));
  Expect.equals("default", test1([true, false]));
  Expect.equals("default", test1([C(), C()]));
  Expect.equals("default", test1([1, 2, 3]));
  Expect.equals("default", test1([1]));
  Expect.equals("default", test1([1, "2", 3]));
  Expect.equals("default", test1(["x"]));

  Expect.equals("[<int>1, <String>x]", test2([ 1, "x"]));
  Expect.equals("[<int>42, <String>answer]", test2([42, "answer"]));
  Expect.equals("[<int>1, <int>2]", test2([1, 2]));
  Expect.equals("[<int>3, <int>4]", test2([3, 4]));
  Expect.equals("[<String>x, <bool>true]", test2(["x", true]));
  Expect.equals("[<String>y, <bool>false]", test2(["y", false]));
  Expect.equals("[<int>0, final false]", test2([0, false]));
  Expect.equals("[<int>1, final C]", test2([1, C()]));
  Expect.equals("default", test2([true, false]));
  Expect.equals("default", test2([C(), C()]));
  Expect.equals("default", test2([1, 2, 3]));
  Expect.equals("default", test2([1]));
  Expect.equals("default", test2([1, "2", 3]));
  Expect.equals("default", test2(["x"]));

  Expect.equals("[<int>1, <String>x]", test3([ 1, "x"]));
  Expect.equals("[<int>42, <String>answer]", test3([42, "answer"]));
  Expect.equals("[<int>1, <int>2]", test3([1, 2]));
  Expect.equals("[<int>3, <int>4]", test3([3, 4]));
  Expect.equals("[<String>x, <bool>true]", test3(["x", true]));
  Expect.equals("[<String>y, <bool>false]", test3(["y", false]));
  Expect.equals("[<int>0, final false]", test3([0, false]));
  Expect.equals("[<int>1, final C]", test3([1, C()]));
  Expect.equals("default", test3([true, false]));
  Expect.equals("default", test3([C(), C()]));
  Expect.equals("default", test3([1, 2, 3]));
  Expect.equals("default", test3([1]));
  Expect.equals("default", test3([1, "2", 3]));
  Expect.equals("default", test3(["x"]));
}