LibTest/collection/ListMixin/listmixin_lib.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 ListMixin<E> abstract class 
/// Implements List<E>
/// Base implementation of a List class.
/// ListMixin can be used as a mixin to make a class implement the List interface.
/// This implements all read operations using only the length and operator[]
/// members. It implements write operations using those and length= and
/// operator[]=
/// @description Implementation of operator[]= and length=
/// @author sgrekhov@unipro.ru

library list_mixin_lib;
import "dart:collection";

class MyList<E> extends Object with ListMixin<E> {
  List<E> _list;

  MyList.empty(): _list = new List<E>.empty(growable: true);
  MyList(int length, E fill): _list = new List<E>.filled(length, fill);
  
  E operator [](int index) => _list[index];

  void operator []=(int index, E value) {
    _list[index] = value;
  }

  int get length => _list.length;

  void set length(int newLength) {
    _list.length = newLength;
  }
}
 
List<E> create<E>([int? length, E? fill]) {
  if (length == null) {
    return new MyList<E>.empty();
  }
  if (fill != null) {
    return new MyList(length, fill);
  }
  throw new Exception("List length specified but fill is null");
}