private static IOrderedDataProducer <TSource> OrderBy <TSource, TKey>(IDataProducer <TSource> source, DotNet20.Func <TSource, TKey> selector, IComparer <TKey> comparer, bool descending)
{
source.ThrowIfNull("source");
comparer.ThrowIfNull("comparer");
IComparer <TSource> itemComparer = new ProjectionComparer <TSource, TKey>(selector, comparer);
if (descending)
{
itemComparer = itemComparer.Reverse();
}
// first, discard any existing "order by"s by going back to the producer
IOrderedDataProducer <TSource> orderedProducer;
bool first = true;
while ((orderedProducer = source as IOrderedDataProducer <TSource>) != null)
{
if (first)
{
// keep the top-most comparer to enforce a balanced sort
itemComparer = new LinkedComparer <TSource>(itemComparer, orderedProducer.Comparer);
first = false;
}
source = orderedProducer.BaseProducer;
}
return(new OrderedDataProducer <TSource>(source, itemComparer));
}
private static IOrderedDataProducer <TSource> ThenBy <TSource, TKey>(IOrderedDataProducer <TSource> source, DotNet20.Func <TSource, TKey> selector, IComparer <TKey> comparer, bool descending)
{
comparer.ThrowIfNull("comparer");
IComparer <TSource> itemComparer = new ProjectionComparer <TSource, TKey>(selector, comparer);
if (descending)
{
itemComparer = itemComparer.Reverse();
}
itemComparer = new LinkedComparer <TSource>(source.Comparer, itemComparer);
return(new OrderedDataProducer <TSource>(source, itemComparer));
}
