using System.Runtime.CompilerServices; namespace System.Reactive { [System.Runtime.CompilerServices.NullableContext(1)] [System.Runtime.CompilerServices.Nullable(0)] internal sealed class ImmutableList<[System.Runtime.CompilerServices.Nullable(2)] T> { public static readonly ImmutableList<T> Empty = new ImmutableList<T>(); private readonly T[] _data; public T[] Data => _data; private ImmutableList() { _data = Array.Empty<T>(); } public ImmutableList(T[] data) { _data = data; } public ImmutableList<T> Add(T value) { T[] array = new T[_data.Length + 1]; Array.Copy(_data, array, _data.Length); array[_data.Length] = value; return new ImmutableList<T>(array); } public ImmutableList<T> Remove(T value) { int num = Array.IndexOf<T>(_data, value); if (num < 0) return this; int num2 = _data.Length; if (num2 == 1) return Empty; T[] array = new T[num2 - 1]; Array.Copy(_data, 0, array, 0, num); Array.Copy(_data, num + 1, array, num, num2 - num - 1); return new ImmutableList<T>(array); } } }