List Notifier - 07/10/2020

list_notifier.dart

// MIT License
//
// Copyright (c) 2020 Simon Lightfoot & Scott Stoll
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import 'dart:collection';

import 'package:flutter/foundation.dart' show ChangeNotifier, ValueListenable;

class ListNotifier<T> extends ChangeNotifier with ListMixin<T> implements ValueListenable<List<T>> {
  ListNotifier([List<T> data]) : _data = data ?? <T>[];

  final List<T> _data;

  @override
  List<T> get value => UnmodifiableListView<T>(_data);

  @override
  int get length => _data.length;

  @override
  set length(int value) {
    _data.length = value;
    notifyListeners();
  }

  @override
  T operator [](int index) => _data[index];

  @override
  void operator []=(int index, T value) {
    _data[index] = value;
    notifyListeners();
  }
}