public void AddFirst(T value)
{
CustomLinkedListNode <T> node = new CustomLinkedListNode <T>(value);
// Save off the head node so we don't lose it
CustomLinkedListNode <T> temp = this.head;
// Point head to the new node
this.head = node;
// Insert the rest of the list behind head
this.head.Next = temp;
if (this.Count == 0)
{
// if the list was empty then head and tail should
// both point to the new node.
this.tail = this.head;
}
else
{
// Before: head -------> 5 <-> 7 -> null
// After: head -> 3 <-> 5 <-> 7 -> null
temp.Previous = this.head;
}
this.Count++;
}
public void CopyTo(T[] array, int arrayIndex)
{
CustomLinkedListNode <T> current = this.head;
while (current != null)
{
array[arrayIndex++] = current.Value;
current = current.Next;
}
}
IEnumerator <T> IEnumerable <T> .GetEnumerator()
{
CustomLinkedListNode <T> current = this.head;
while (current != null)
{
yield return(current.Value);
current = current.Next;
}
}
public bool Remove(T item)
{
CustomLinkedListNode <T> previous = null;
CustomLinkedListNode <T> current = this.head;
// 1: Empty list - do nothing
// 2: Single node: (previous is null)
// 3: Many nodes
// a: node to remove is the first node
// b: node to remove is the middle or last
while (current != null)
{
// Head -> 3 -> 5 -> 7 -> null
// Head -> 3 ------> 7 -> null
if (current.Value.Equals(item))
{
// it's a node in the middle or end
if (previous != null)
{
// Case 3b
previous.Next = current.Next;
// it was the end - so update Tail
if (current.Next == null)
{
this.tail = previous;
}
else
{
// Before: Head -> 3 <-> 5 <-> 7 -> null
// After: Head -> 3 <-------> 7 -> null
// previous = 3
// current = 5
// current.Next = 7
// So... 7.Previous = 3
current.Next.Previous = previous;
}
this.Count--;
}
else
{
// Case 2 or 3a
this.RemoveFirst();
}
return(true);
}
previous = current;
current = current.Next;
}
return(false);
}
public bool Contains(T item)
{
CustomLinkedListNode <T> current = this.head;
while (current != null)
{
if (current.Value.Equals(item))
{
return(true);
}
current = current.Next;
}
return(false);
}
public void AddLast(T value)
{
CustomLinkedListNode <T> node = new CustomLinkedListNode <T>(value);
if (this.Count == 0)
{
this.head = node;
}
else
{
this.tail.Next = node;
// Before: Head -> 3 <-> 5 -> null
// After: Head -> 3 <-> 5 <-> 7 -> null
// 7.Previous = 5
node.Previous = this.tail;
}
this.tail = node;
this.Count++;
}
public void RemoveLast()
{
if (this.Count != 0)
{
if (this.Count == 1)
{
this.head = null;
this.tail = null;
}
else
{
// Before: Head --> 3 --> 5 --> 7
// Tail = 7
// After: Head --> 3 --> 5 --> null
// Tail = 5
// Null out 5's Next pointerproperty
this.tail.Previous.Next = null;
this.tail = this.tail.Previous;
}
this.Count--;
}
}
public void RemoveFirst()
{
if (this.Count != 0)
{
// Before: Head -> 3 <-> 5
// After: Head -------> 5
// Head -> 3 -> null
// Head ------> null
this.head = this.head.Next;
this.Count--;
if (this.Count == 0)
{
this.tail = null;
}
else
{
// 5.Previous was 3, now null
this.head.Previous = null;
}
}
}
public void Clear()
{
this.head = null;
this.tail = null;
this.Count = 0;
}