Comparer.cs

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using System.Runtime.CompilerServices;
 
namespace System.Collections.Generic;
 
[Serializable]
[TypeDependency("System.Collections.Generic.ObjectComparer`1")]
[TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
public abstract class Comparer<T> : IComparer, IComparer<T>
{
    public static Comparer<T> Default
    {
        [Intrinsic]
        get;
    } = (Comparer<T>)ComparerHelpers.CreateDefaultComparer(typeof(T));
 
 
    public static Comparer<T> Create(Comparison<T> comparison)
    {
        if (comparison == null)
        {
            throw new ArgumentNullException("comparison");
        }
        return new ComparisonComparer<T>(comparison);
    }
 
    public abstract int Compare(T? x, T? y);
 
    int IComparer.Compare(object x, object y)
    {
        if (x == null)
        {
            if (y != null)
            {
                return -1;
            }
            return 0;
        }
        if (y == null)
        {
            return 1;
        }
        if (x is T && y is T)
        {
            return Compare((T)x, (T)y);
        }
        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArgumentForComparison);
        return 0;
    }
}