public INode <T> AddBefore(INode <T> node, T value)
{
if (FirstNode == null)
{
throw new InvalidOperationException("List is empty");
}
else if (FirstNode == node)
{
// There's no previous node since it's the first one,
// possibly because this.Count == 1.
return(AddFirst(value));
}
else
{
INode <T> prevNode = FindPrevious(node);
if (prevNode == null)
{
throw new InvalidOperationException(
"node " + node.Value + "not in list");
}
INode <T> newNode = new SinglyLinkedNode <T>(value);
newNode.Next = node;
prevNode.Next = newNode;
Count++;
return(newNode);
}
}
public INode <T> AddLast(T value)
{
var newLastNode = new SinglyLinkedNode <T>(value);
if (FirstNode == null)
{
// list is empty
FirstNode = LastNode = newLastNode;
}
else
{
LastNode.Next = newLastNode;
LastNode = newLastNode;
}
Count++;
return(newLastNode);
}
public INode <T> AddFirst(T value)
{
var newFirstNode = new SinglyLinkedNode <T>(value);
if (FirstNode == null)
{
// Empty list
FirstNode = LastNode = newFirstNode;
}
else
{
newFirstNode.Next = FirstNode;
FirstNode = newFirstNode;
}
Count++;
return(newFirstNode);
}
public INode <T> AddAfter(INode <T> node, T value)
{
var newNode = new SinglyLinkedNode <T>(value);
node = Find(node);
try
{
newNode.Next = node.Next;
if (LastNode == node)
{
LastNode = newNode;
}
node.Next = newNode;
Count++;
return(newNode);
}
catch (NullReferenceException)
{
throw new InvalidOperationException(
"node " + node.Value + "not in list");
}
}
public SinglyLinkedList(T value)
{
FirstNode = LastNode = new SinglyLinkedNode <T>(value);
}
