LanguageFeatures/Control-flow-collections/type_inference_A13_t04.dart

/*
 * Copyright (c) 2019, 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 If element is a forElement with element e1 then:
 *
 * Inference for the iterated expression and the controlling variable is done as
 * for the corresponding for or await for statement.
 *
 * If the inferred key type of e1 is K and the inferred key type of e1 is V then
 * the inferred key and value types of element are K and V
 *
 * @description Checks that if element is a forElement with element e1 then if
 * the inferred key type of e1 is K and the inferred key type of e1 is V then
 * the inferred key and value types of element are K and V
 * @author sgrekhov@unipro.ru
 */
// SharedOptions=--enable-experiment=constant-update-2018
import "../../Utils/expect.dart";

main() {
  var collection = [1, 2, 3, 4, 5];
  var c1 = {1: 1, 2: 2, 3: 3};
  var c2 = {1.1: 1.1, 2.2: 2.2, 3.3: 3.3};

  var map1 = {
  for (var i in collection)
    if (i.isEven) ...c1 else ...c2
  };
  Expect.isTrue(map1 is Map<num, num>);
  Expect.isFalse(map1 is Map<int, num>);
  Expect.isFalse(map1 is Map<double, num>);
  Expect.isFalse(map1 is Map<num, int>);
  Expect.isFalse(map1 is Map<num, double>);

  var map2 = {
    "": "",
    for (var i in collection)
      if (i.isEven) ...?c1 else ...?c2
  };
  Expect.isTrue(map2 is Map<Object, Object>);
  Expect.isFalse(map2 is Map<Object, num>);
  Expect.isFalse(map2 is Map<Object, String>);
  Expect.isFalse(map2 is Map<String, Object>);
  Expect.isFalse(map2 is Map<num, Object>);

  c1 = null;
  c2 = null;
  var map3 = {
    for (var i in collection)
      if (i.isEven) ...?c1 else ...?c2
  };
  Expect.isTrue(map3 is Map<num, num>);
  Expect.isFalse(map3 is Map<int, num>);
  Expect.isFalse(map3 is Map<double, num>);
  Expect.isFalse(map3 is Map<num, int>);
  Expect.isFalse(map3 is Map<num, double>);
}