public static IOrderingImpl <T> ThenByDescending <T, TKey>(this IOrderingImpl <T> source, Func <T, TKey> comparer)
where TKey : IComparable <TKey>
{
Comparison <T> descendingComparer = (left, right) => comparer(right).CompareTo(comparer(left));
return(new MyOrderedEnumerable <T, TKey>(source, descendingComparer));
}
public MyOrderedEnumerable(IOrderingImpl <T> source, Comparison <T> comparison)
{
this.source = source;
this.comparison = (a, b) =>
{
var originalComparison = source.CompareTo(a, b);
if (originalComparison != 0)
{
return(originalComparison);
}
return(comparison(a, b));
};
}
public MyOrderedEnumerable(IOrderingImpl <T> source, Func <T, TKey> comparer)
{
this.source = source;
comparison = (a, b) =>
{
var originalComparison = source.CompareTo(a, b);
if (originalComparison != 0)
{
return(originalComparison);
}
return(comparer(a).CompareTo(comparer(b)));
};
}
public static IOrderingImpl <T> MyThenBy <T, TKey>(this IOrderingImpl <T> source, Func <T, TKey> comparer)
where TKey : IComparable <TKey>
{
return(new MyOrderedEnumerable <T, TKey>(source, comparer));
}