flutter-go/lib/widgets/components/List/AnimatedList/model.dart

/// Created with Android Studio.
/// User: 一晟
/// Date: 2018/12/31
/// Time: 下午10:15
/// email: zhu.yan@alibaba-inc.com
/// target: model 的示例

import 'package:flutter/material.dart';

class ListModel<E> {
  ListModel({
    @required this.listKey,
    @required this.removedItemBuilder,
    Iterable<E> initialItems,
  }) : assert(listKey != null),
        assert(removedItemBuilder != null),
        _items =  List<E>.from(initialItems ?? <E>[]);

  final GlobalKey<AnimatedListState> listKey;
  final dynamic removedItemBuilder;
  final List<E> _items;

  AnimatedListState get _animatedList => listKey.currentState;

  void insert(int index, E item) {
    _items.insert(index, item);
    _animatedList.insertItem(index);
  }

  E removeAt(int index) {
    final E removedItem = _items.removeAt(index);
    if (removedItem != null) {
      _animatedList.removeItem(index, (BuildContext context, Animation<double> animation) {
        return removedItemBuilder(removedItem, context, animation);
      });
    }
    return removedItem;
  }

  int get length => _items.length;
  E operator [](int index) => _items[index];
  int indexOf(E item) => _items.indexOf(item);
}