static IImmutableStack <T> GetPrevElementInHierarchyCore <T>(IImmutableStack <T> rootStack, Func <T, IList <T> > getChildren, Func <IList <T>, T, int> indedOf) where T : class
{
var currentElement = rootStack.Peek();
Func <T, IEnumerable <T> > getChildrenPath = element => LinqExtensions.Unfold(element, x => getChildren(x).LastOrDefault(), x => x == null);
var parents = rootStack.Pop();
var parent = parents.FirstOrDefault();
if (parent == null)
{
return(ImmutableStack.Empty <T>().PushMultiple(getChildrenPath(currentElement)));
}
var neighbors = getChildren(parent);
var index = indedOf(neighbors, currentElement);
if (index > 0)
{
return(parents.PushMultiple(getChildrenPath(neighbors[index - 1])));
}
return(parents);
}
static IEnumerable <Type> GetAttributeTypes(Attribute attr)
{
return(LinqExtensions.Unfold(attr.GetType(), x => x.BaseType, x => x == typeof(Attribute)));
}