LexicographicListComparer.cs

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using System;
using System.Collections.Generic;
 
namespace IKVM.CoreLib.System
{
 
    internal class LexicographicListComparer<T> : LexicographicListComparer<T, IComparer<T>>
    {
 
        public new static readonly LexicographicListComparer<T> Default = new LexicographicListComparer<T>(Comparer<T>.Default);
 
        public LexicographicListComparer(IComparer<T> comparer) :
            base(comparer)
        {
 
        }
 
    }
 
    internal class LexicographicListComparer<T, TComparer> : LexicographicListComparer<T, IComparer<T>, IReadOnlyList<T>>
    {
 
        public new static readonly LexicographicListComparer<T, TComparer> Default = new LexicographicListComparer<T, TComparer>(Comparer<T>.Default);
 
        public LexicographicListComparer(IComparer<T> comparer) :
            base(comparer)
        {
 
        }
 
    }
 
    class LexicographicListComparer<T, TComparer, TList> : Comparer<TList>
        where TComparer : IComparer<T>
        where TList : IReadOnlyList<T>
    {
 
        readonly TComparer _comparer;
 
        public LexicographicListComparer(TComparer comparer)
        {
            _comparer = comparer;
        }
 
        public override int Compare(TList? x, TList? y)
        {
            if (x == null && y is null)
                return 0;
 
            if (x == null)
                return +1;
 
            if (y == null)
                return -1;
 
            int c = x.Count.CompareTo(y.Count);
            if (c != 0)
                return c;
 
            var length = Math.Min(x.Count, y.Count);
            for (int i = 0; i < length; i++)
            {
                c = _comparer.Compare(x[i], y[i]);
                if (c != 0)
                    return c;
            }
 
            return 0;
        }
 
    }
 
}