특정 아이템을 맨 앞이나 맨 뒤로 보낼 수 있는 Collection입니다. Recent Files 같은 최근 시스템을 만들때 사용됩니다

RecentCollection.cs

public class RecentCollection<T> : ICollection<T>
{
    public RecentCollection()
    {
        _collection = new List<T>();
    }

    public RecentCollection(int capacity)
    {
        _collection = new List<T>(capacity);
    }

    public RecentCollection(IEnumerable<T> collection)
    {
        _collection = new List<T>(collection);
    }

    private ICollection<T> _collection;

    public int Count => _collection.Count;

    public bool IsReadOnly => _collection.IsReadOnly;

    public void Add(T item)
        => _collection.Add(item);

    public void Clear()
        => _collection.Clear();

    public bool Contains(T item)
        => _collection.Contains(item);

    public void CopyTo(T[] array, int arrayIndex)
        => _collection.CopyTo(array, arrayIndex);

    public IEnumerator<T> GetEnumerator()
        => _collection.GetEnumerator();

    public bool Remove(T item)
        => _collection.Remove(item);

    public void Top(int index)
    {
        var item = _collection.ElementAt(index);

        _collection.Remove(item);
        var list = new List<T>(_collection);

        list.Insert(0, item);

        _collection = list;
    }

    public void Bottom(int index)
    {
        var item = _collection.ElementAt(index);

        _collection.Remove(item);
        _collection.Add(item);
    }

    IEnumerator IEnumerable.GetEnumerator()
        => ((IEnumerable)_collection).GetEnumerator();
}