LibTest/collection/LinkedHashSet/LinkedHashSet_A05_t04.dart

// Copyright (c) 2016, 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 LinkedHashMap({bool equals(K key1, K key2), int hashCode(K key),
 * bool isValidKey(potentialKey)})
 * If the [equals] or [hashCode] methods won't work on all objects, but only on
 * some instances of [E], the [isValidKey] predicate can be used to restrict the
 * keys that the functions are applied to. Any key for which [isValidKey]
 * returns false is automatically assumed to not be in the set when asking
 * [contains].
 * @description Checks that if [isValidKey] returns [false] then value is in set
 * in spite of [contains] returns [false]
 * @author sgrekhov@unipro.ru
 */
import "../../../Utils/expect.dart";
import "dart:collection";

bool isValidKey(var potentialKey) {
  return potentialKey < 100;
}

main() {
  LinkedHashSet set = new LinkedHashSet(isValidKey: isValidKey);

  set.add(1);
  Expect.isTrue(set.contains(1));

  set.add(101);
  Expect.isFalse(set.contains(101));

  Expect.equals(2, set.length);
  Expect.equals(1, set.elementAt(0));
  Expect.equals(101, set.elementAt(1));
}