public int CompareTo(DLinkedListNode <T> other)
{
if (other == null)
{
return(-1);
}
return(this.Data.CompareTo(other.Data));
}
public bool MovePrevious()
{
if (_current.Previous != null)
{
_current = _current.Previous;
}
else
{
return(false);
}
return(true);
}
public bool MoveNext()
{
if (_current.Next != null)
{
_current = _current.Next;
}
else
{
return(false);
}
return(true);
}
/// <summary>
/// Returns a number of elements as specified by countOfElements, starting from the specified index.
/// </summary>
/// <param name="index">Starting index.</param>
/// <param name="countOfElements">The number of elements to return.</param>
/// <returns>Doubly-Linked List of elements</returns>
public virtual DLinkedList <T> GetRange(int index, int countOfElements)
{
DLinkedListNode <T> currentNode = null;
DLinkedList <T> newList = new DLinkedList <T>();
// Handle Index out of Bound errors
if (Count == 0)
{
return(newList);
}
else if (index < 0 || index > Count)
{
throw new IndexOutOfRangeException();
}
// Decide from which reference to traverse the list, and then move the currentNode reference to the index
// If index > half then traverse it from the end (_lastNode reference)
// Otherwise, traverse it from the beginning (_firstNode refrence)
if (index > (Count / 2))
{
currentNode = this._lastNode;
for (int i = (Count - 1); i > index; --i)
{
currentNode = currentNode.Previous;
}
}
else
{
currentNode = this._firstNode;
for (int i = 0; i < index; ++i)
{
currentNode = currentNode.Next;
}
}
// Append the elements to the new list using the currentNode reference
while (currentNode != null && newList.Count <= countOfElements)
{
newList.Append(currentNode.Data);
currentNode = currentNode.Next;
}
return(newList);
}
/// <summary>
/// Append the specified dataItem at the end of the list.
/// </summary>
/// <param name="dataItem">Data item.</param>
public virtual void Append(T dataItem)
{
DLinkedListNode <T> newNode = new DLinkedListNode <T>(dataItem);
if (_firstNode == null)
{
_firstNode = _lastNode = newNode;
}
else
{
var currentNode = _lastNode;
currentNode.Next = newNode;
newNode.Previous = currentNode;
_lastNode = newNode;
}
// Increment the count.
_count++;
}
/// <summary>
/// Gets the element at the specified index
/// </summary>
/// <param name="index">Index of element</param>
/// <returns>Element</returns>
protected virtual T _getElementAt(int index)
{
if (IsEmpty() || index < 0 || index >= Count)
{
throw new IndexOutOfRangeException("List is empty.");
}
if (index == 0)
{
return(First);
}
else if (index == (Count - 1))
{
return(Last);
}
else
{
DLinkedListNode <T> currentNode = null;
// Decide from which reference to traverse the list, and then move the currentNode reference to the index
// If index > half then traverse it from the end (_lastNode reference)
// Otherwise, traverse it from the beginning (_firstNode refrence)
if (index > (Count / 2))
{
currentNode = this._lastNode;
for (int i = (Count - 1); i > index; --i)
{
currentNode = currentNode.Previous;
}
}
else
{
currentNode = this._firstNode;
for (int i = 0; i < index; ++i)
{
currentNode = currentNode.Next;
}
}
return(currentNode.Data);
}
}
/// <summary>
/// Inserts the dataItem at the specified index.
/// </summary>
/// <param name="dataItem">Data item.</param>
/// <param name="index">Index.</param>
public virtual void InsertAt(T dataItem, int index)
{
if (index < 0 || index > Count)
{
throw new IndexOutOfRangeException();
}
if (index == 0)
{
Prepend(dataItem);
}
else if (index == Count)
{
Append(dataItem);
}
else
{
DLinkedListNode <T> currentNode = null;
DLinkedListNode <T> newNode = new DLinkedListNode <T>(dataItem);
currentNode = this._firstNode;
for (int i = 0; i < index - 1; ++i)
{
currentNode = currentNode.Next;
}
var oldNext = currentNode.Next;
if (oldNext != null)
{
currentNode.Next.Previous = newNode;
}
newNode.Next = oldNext;
currentNode.Next = newNode;
newNode.Previous = currentNode;
// Increment the count
_count++;
}
}
public void Dispose()
{
_current = null;
_doublyLinkedList = null;
}
public void Reset()
{
_current = _doublyLinkedList.Head;
}
public DLinkedListEnumerator(DLinkedList <T> list)
{
this._current = list.Head;
this._doublyLinkedList = list;
}
/// <summary>
/// Remove the specified dataItem.
/// </summary>
public virtual void RemoveFirstMatch(Predicate <T> match)
{
// Handle index out of bound errors
if (IsEmpty())
{
throw new IndexOutOfRangeException();
}
if (match(_firstNode.Data))
{
_firstNode = _firstNode.Next;
if (_firstNode != null)
{
_firstNode.Previous = null;
}
}
else if (match(_lastNode.Data))
{
_lastNode = _lastNode.Previous;
if (_lastNode != null)
{
_lastNode.Next = null;
}
}
else
{
// Remove
var currentNode = _firstNode;
// Get currentNode to reference the element at the index.
while (currentNode.Next != null)
{
if (match(currentNode.Data))
{
break;
}
currentNode = currentNode.Next;
}//end-while
// If we reached the last node and item was not found
// Throw exception
if (!match(currentNode.Data))
{
throw new Exception("Item was not found!");
}
// Remove element
DLinkedListNode <T> newPrevious = currentNode.Previous;
DLinkedListNode <T> newNext = currentNode.Next;
if (newPrevious != null)
{
newPrevious.Next = newNext;
}
if (newNext != null)
{
newNext.Previous = newPrevious;
}
currentNode = newPrevious;
}
// Decrement count.
_count--;
}
public DLinkedListNode(T dataItem, DLinkedListNode <T> next, DLinkedListNode <T> previous)
{
Data = dataItem;
Next = next;
Previous = previous;
}