using System;
using System.Collections.Generic;

using Microsoft.Xna.Framework;

namespace Nuclex
{
    internal class UpdateOrderComparer : IComparer<IUpdateable>
    {
        // Fields
        public static readonly UpdateOrderComparer Default = new UpdateOrderComparer();

        // Methods
        public int Compare(IUpdateable x, IUpdateable y)
        {
            if ((x == null) && (y == null))
            {
                return 0;
            }
            if (x != null)
            {
                if (y == null)
                {
                    return -1;
                }
                if (x.Equals(y))
                {
                    return 0;
                }
                if (x.UpdateOrder < y.UpdateOrder)
                {
                    return -1;
                }
            }
            return 1;
        }
    }
} // namespace Nuclex