public static IReadOnlyList <T> From(IReadOnlyList <T> subList, int enforcedMinimumCount)
{
if (subList == null)
{
throw new ArgumentNullException("subList");
}
if (enforcedMinimumCount < 0)
{
throw new ArgumentOutOfRangeException("enforcedMinimumCount", "enforcedMinimumCount < 0");
}
if (subList.Count < enforcedMinimumCount)
{
throw new ArgumentOutOfRangeException("subList", "subList.Count < enforcedMinimumCount");
}
// if the sub list is guaranteed to be big enough, no need to do anything
if (enforcedMinimumCount <= subList.TryGetMinCount())
{
return(subList);
}
// if the sublist is another count check, we can replace it
// (it must have a looser condition or else the minimum count check would have succeeded)
var c = subList as ListCountCheck <T>;
if (c != null)
{
return(From(c.SubList, enforcedMinimumCount));
}
// if the sublist is a Take then we can push the check downwards
var tf = subList as ListTakeFirst <T>;
if (tf != null)
{
return(ListTakeFirst <T> .From(From(tf.SubList, enforcedMinimumCount), tf.Amount));
}
// if the sublist is a TakeLast then we can push the check downwards
var tl = subList as ListTakeLast <T>;
if (tl != null)
{
return(ListTakeLast <T> .From(From(tl.SubList, enforcedMinimumCount), tl.Amount));
}
// if the sublist is a Skip then we can push the check downwards
var s = subList as ListSkip <T>;
if (s != null)
{
return(ListSkip <T> .From(From(s.SubList, enforcedMinimumCount + s.Amount), s.Offset, s.Amount));
}
// if the sublist is an adapter, we can push the check downwards
var a = subList as ListAdapter <T>;
if (a != null)
{
return(ListAdapter <T> .From(From(a.List, enforcedMinimumCount)));
}
return(new ListCountCheck <T>(subList, enforcedMinimumCount));
}