public static TSource LastOrDefault <TSource>(this IEnumerable <TSource> source)
{
if (source == null)
{
throw Error.ArgumentNull("source");
}
IPartition <TSource> partition = source as IPartition <TSource>;
if (partition != null)
{
return(partition.LastOrDefault());
}
IList <TSource> list = source as IList <TSource>;
if (list != null)
{
int count = list.Count;
if (count > 0)
{
return(list[count - 1]);
}
}
else
{
using (IEnumerator <TSource> e = source.GetEnumerator())
{
if (e.MoveNext())
{
TSource result;
do
{
result = e.Current;
} while (e.MoveNext());
return(result);
}
}
}
return(default(TSource));
}
