public static ISubscribable <T> Partition <T, TKey>(this ISubscribable <T> source, Expression <Func <T, TKey> > filter, IEqualityComparer <TKey> keyComparer, TKey value)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
if (filter == null)
{
throw new ArgumentNullException(nameof(filter));
}
if (keyComparer == null)
{
throw new ArgumentNullException(nameof(keyComparer));
}
if (source is QuotedSubscribable <T> quotedPartitionableSubscribable)
{
source = quotedPartitionableSubscribable.Value;
}
if (source is IPartitionableSubscribable <T> partitionableSubscribable)
{
return(partitionableSubscribable.AddPartition(filter).Bind(value, keyComparer));
}
if (source is IPartitionedMultiSubject <T> partitionedMultiSubject)
{
return(partitionedMultiSubject.CreatePartitionableSubscribable().AddPartition(filter).Bind(value, keyComparer));
}
// This is the case where the input is not a partitionable artifact. In practice we should only delegate if the input is partitionable,
// so this case should not be hit.
var eq = EqualityComparerReflectionHelper <TKey> .EqualsMethod;
var p = filter.Parameters.Single();
var f = Expression.Lambda <Func <T, bool> >(Expression.Call(Expression.Constant(keyComparer), eq, filter.Body, Expression.Constant(value)), p);
return(source.Where(f.Compile()));
}
private static ISubscribable <TSource> AddFilter <TKey>(ISubscribable <TSource> subscribable, KeyBinding <TSource, TKey> binding)
{
return(subscribable.Where(x => binding.KeyComparer.Equals(binding.KeySelector.Invoke(x), binding.Key)));
}