ReadOnlyListProxy

ReadOnlyListProxy.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Redacted
{
    public static class ReadOnlyListProxy
    {
        public static ReadOnlyListProxy<T, R> From<T, R>(
            IReadOnlyList<T> list, Func<T, R> selector)
        {
            return new ReadOnlyListProxy<T, R>(list, selector);
        }
    }

    public class ReadOnlyListProxy<T, R> : IReadOnlyList<R>
    {
        public IReadOnlyList<T> List
        {
            get { return _list; }
        }

        readonly IReadOnlyList<T> _list;
        readonly Func<T, R> _selector;

        public ReadOnlyListProxy(IReadOnlyList<T> list, Func<T, R> selector)
        {
            _list = list;
            _selector = selector;
        }

        public struct Enumerator : IEnumerator<R>
        {
            readonly IEnumerator<T> _enumerator;
            readonly Func<T, R> _selector;

            public Enumerator(IEnumerator<T> enumerator, Func<T, R> selector)
            {
                _enumerator = enumerator;
                _selector = selector;
            }

            public void Dispose()
            {
                _enumerator.Dispose();
            }

            public bool MoveNext()
            {
                return _enumerator.MoveNext();
            }

            public void Reset()
            {
                _enumerator.Reset();
            }

            public R Current
            {
                get { return _selector(_enumerator.Current); }
            }

            object IEnumerator.Current
            {
                get { return Current; }
            }
        }

        public Enumerator GetEnumerator()
        {
            return new Enumerator(_list.GetEnumerator(), _selector);
        }

        IEnumerator<R> IEnumerable<R>.GetEnumerator()
        {
            return GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        public int Count
        {
            get { return _list.Count; }
        }

        public R this[int index]
        {
            get { return _selector(_list[index]); }
        }
    }
}