using System;

using System.Collections.Generic;

using System.Linq;

​

public static class Program

{

    private static void Main(string[] args)

    {

        var words = new List<string>{"word1 word2", "wordA wordB", "dog cat", "mouse cat"};

        var ordered = words.Select(SpecialComparerInstance.Create)

            .OrderBy(special => special, SpecialComparer.Default)

            .Select(special => special.Value);

​

        foreach (var item in ordered)

        {

            Console.WriteLine(item);

        }

    }

}

​

public class SpecialComparerInstance

{

    public static SpecialComparerInstance Create(string value) => new SpecialComparerInstance(value);

    public SpecialComparerInstance(string value)

    {

        if (string.IsNullOrEmpty(value))

            throw new ArgumentNullException(nameof(value));

        var elements = value.Split(' ');

        if (elements.Length != 2)

            throw new ArgumentException("Must contain exactly one space character", nameof(value));

        Value = value;

        FirstOrderValue = elements[1];

        SecondOrderValue = elements[0];

    }

​

    public string Value { get; }

​

    public string FirstOrderValue { get; }

​

    public string SecondOrderValue { get; }

}

​

public class SpecialComparer : IComparer<SpecialComparerInstance>

{

    public static readonly IComparer<SpecialComparerInstance> Default = new SpecialComparer(StringComparer.Ordinal);

    private readonly StringComparer _comparer;

​

    public SpecialComparer(StringComparer comparer)

    {

        _comparer = comparer;

    }

​

    public int Compare(SpecialComparerInstance x, SpecialComparerInstance y)

    {

        if (ReferenceEquals(x, y))

            return 0;

        if (ReferenceEquals(x, null))

            return 1;

​

        if (ReferenceEquals(y, null))

            return -1;

​

        var result = _comparer.Compare(x.FirstOrderValue, y.FirstOrderValue);

​

        if (result == 0)

            result = _comparer.Compare(x.SecondOrderValue, y.SecondOrderValue);

        return result;

    }

}