public static IOrderedEnumerable <TSource> OrderBy <TSource, TKey>(
this IEnumerable <TSource> source,
Func <TSource, TKey> keySelector,
IComparer <TKey> comparer)
{
if (source == null || keySelector == null)
{
throw new ArgumentNullException("source or selector is null");
}
IComparer <TSource> sourceComparer = new CompareByKey <TSource, TKey>(keySelector, comparer);
return(new OrderedEnumerable <TSource>(source, sourceComparer));
}
public IOrderedEnumerable <TElement> CreateOrderedEnumerable <TKey>(Func <TElement, TKey> keySelector,
IComparer <TKey> comparer,
bool descending)
{
if (keySelector == null)
{
throw new ArgumentNullException("keySelector is null");
}
IComparer <TElement> secondaryComparer =
new CompareByKey <TElement, TKey>(keySelector, comparer);
return(new OrderedEnumerable <TElement>(source,
new CompareObjects <TElement>(currentComparer, secondaryComparer)));
}