Comparer.cs

using System.Globalization;
using System.Runtime.InteropServices;
using System.Runtime.Serialization;
using System.Security;

namespace System.Collections
{
    [Serializable]
    [ComVisible(true)]
    public sealed class Comparer : IComparer, ISerializable
    {
        private CompareInfo m_compareInfo;

        public static readonly Comparer Default = new Comparer(CultureInfo.CurrentCulture);

        public static readonly Comparer DefaultInvariant = new Comparer(CultureInfo.InvariantCulture);

        private const string CompareInfoName = "CompareInfo";

        private Comparer()
        {
            m_compareInfo = null;
        }

        public Comparer(CultureInfo culture)
        {
            if (culture == null)
            {
                throw new ArgumentNullException("culture");
            }
            m_compareInfo = culture.CompareInfo;
        }

        private Comparer(SerializationInfo info, StreamingContext context)
        {
            m_compareInfo = null;
            SerializationInfoEnumerator enumerator = info.GetEnumerator();
            while (enumerator.MoveNext())
            {
                string name = enumerator.Name;
                if (name == "CompareInfo")
                {
                    m_compareInfo = (CompareInfo)info.GetValue("CompareInfo", typeof(CompareInfo));
                }
            }
        }

        public int Compare(object a, object b)
        {
            if (a == b)
            {
                return 0;
            }
            if (a == null)
            {
                return -1;
            }
            if (b == null)
            {
                return 1;
            }
            if (m_compareInfo != null)
            {
                string text = a as string;
                string text2 = b as string;
                if (text != null && text2 != null)
                {
                    return m_compareInfo.Compare(text, text2);
                }
            }
            IComparable comparable = a as IComparable;
            if (comparable != null)
            {
                return comparable.CompareTo(b);
            }
            IComparable comparable2 = b as IComparable;
            if (comparable2 != null)
            {
                return -comparable2.CompareTo(a);
            }
            throw new ArgumentException(Environment.GetResourceString("Argument_ImplementIComparable"));
        }

        [SecurityCritical]
        public void GetObjectData(SerializationInfo info, StreamingContext context)
        {
            if (info == null)
            {
                throw new ArgumentNullException("info");
            }
            if (m_compareInfo != null)
            {
                info.AddValue("CompareInfo", m_compareInfo);
            }
        }
    }
}