HashSet in Dart

hashSet.dart

class CustomHashSet {
  CustomHashSet();

  final _keys = List<List<int>>.generate(1000, (index) => []);
  
  List<List<int>> get keys {
    return _keys;
  }
  
  int _hashFunction(int key) {
    return key % 1000;
  }

  void add(int key) {
    int index = _hashFunction(key);

    if (!contains(key)) {
      _keys[index].add(key);
    }
  }

  void remove(int key) {
    int index = _hashFunction(key);

    if (contains(key)) {
      int indexToRemove = 0;

      for (int value = 0; value < _keys[index].length; value++) {
        if (_keys[index][value] == key) {
          indexToRemove = value;
        }
      }

      _keys[index].removeAt(indexToRemove);
    }
  }

  bool contains(int key) {
    int index = _hashFunction(key);
    for (int value = 0; value < _keys[index].length; value++) {
      if (_keys[index][value] == key) {
        return true;
      }
    }

    return false;
  }
}