UniqueList.cs

//Credit to felixkmh https://github.com/felixkmh/DuplicateHider/
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HtmlExporterPlugin
{
    public class UniqueList<T> : IList<T>
    {
        internal List<T> data;

        public UniqueList() => data = new List<T>();

        public UniqueList(IEnumerable<T> collection) => data = new List<T>(collection);

        public UniqueList(int capacity) => data = new List<T>(capacity);

        public T this[int index] { get => data[index]; set => data[index] = value; }

        public int Count => data.Count;

        public bool IsReadOnly => false;

        public void Add(T item)
        {
            if (!data.Contains(item)) data.Add(item);
        }

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

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


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

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

        public int IndexOf(T item) => data.IndexOf(item);

        public void Insert(int index, T item) => data.Insert(index, item);

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

        public void RemoveAt(int index) => data.RemoveAt(index);

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