using System.Collections.Generic;
using System.Diagnostics.Contracts;

namespace Novacoin
{
    static class IListExtensions
    {
        public static void Swap<T>(
            this IList<T> list,
            int firstIndex,
            int secondIndex
        )
        {
            Contract.Requires(list != null);
            Contract.Requires(firstIndex >= 0 && firstIndex < list.Count);
            Contract.Requires(secondIndex >= 0 && secondIndex < list.Count);
            if (firstIndex == secondIndex)
            {
                return;
            }
            T temp = list[firstIndex];
            list[firstIndex] = list[secondIndex];
            list[secondIndex] = temp;
        }
    }
}