public static IComparer <T> Create <TKey1, TKey2>(Func <T, TKey1> keySelector1, Func <T, TKey2> keySelector2)
{
if (keySelector1 == null)
{
throw new ArgumentNullException(nameof(keySelector1));
}
if (keySelector2 == null)
{
throw new ArgumentNullException(nameof(keySelector2));
}
var c1 = Comparer2 <TKey1> .GetDefault();
var c2 = Comparer2 <TKey2> .GetDefault();
return(Comparer <T> .Create((x, y) =>
{
var d = c1.Compare(keySelector1(x), keySelector1(y));
if (d != 0)
{
return d;
}
return c2.Compare(keySelector2(x), keySelector2(y));
}));
}
public static IComparer <T> Create <TKey>(Func <T, TKey> keySelector, bool descending = false)
{
if (keySelector == null)
{
throw new ArgumentNullException(nameof(keySelector));
}
var c = Comparer2 <TKey> .GetDefault();
if (descending)
{
return(Comparer <T> .Create((x, y) => c.Compare(keySelector(y), keySelector(x))));
}
else
{
return(Comparer <T> .Create((x, y) => c.Compare(keySelector(x), keySelector(y))));
}
}
