public LinkedListEnumerator(DoublyCircularLinkedList <T> l)
{
this.l = l;
this._p = l._head;
this._idx = 1;
_c = default(T);
}
//MAKENULL
public void Clear()
{
this._count = 0;
this._head = new DoubleElementType <T>();
this._tail = new DoubleElementType <T>();
this._tail.Next = _head;
this._head.Previous = _tail;
this._head.Next = _tail;
this._tail.Previous = _head;
}
public DoublyCircularLinkedList()
{
this._count = 0;
this._head = new DoubleElementType <T>();
this._tail = new DoubleElementType <T>();
this._tail.Next = _head;
this._head.Previous = _tail;
this._head.Next = _tail;
this._tail.Previous = _head;
}
public T MovePrevious()
{
if (HasPrevious())
{
_idx--;
_p = _p.Previous;
_c = _p.Element;
return(_c);
}
_c = default(T);
return(_c);
}
public T MoveNext()
{
if (HasNext())
{
_idx++;
_p = _p.Next;
_c = _p.Element;
return(_c);
}
_c = default(T);
return(_c);
}
//0 pointer to the _head. So pos must be [1..count]
public void Insert(Int32 p, T item)
{
Int32 np = p;
if (p <= 0)
{
np = (_count + 1) - Math.Abs(p);
}
else if (Math.Abs(p) > _count + 1)
{
np = Math.Abs(p) - _count + 1;
}
#region _tail
//if(IsEmpty)
if (Count == 0)
{
this._tail.Element = item;
_count += 1;
return;
}
//Append.
else if (np == Count + 1)//or p == 0
{
_tail.Next = new DoubleElementType <T>();
_tail.Next.Element = item;
DoubleElementType <T> pr = _tail;
_tail = _tail.Next;
_tail.Next = _head;
_tail.Previous = pr;
_head.Previous = _tail;
_count += 1;
return;
}
#endregion
Int32 q = 1;
DoubleElementType <T> elem = new DoubleElementType <T>();
elem.Element = item;
DoubleElementType <T> temp = _head; //_head pos = 0.
while (q < p) //move to p.
{
temp = temp.Next;
q += 1;
}
DoubleElementType <T> pp = temp;
temp = temp.Next; //temp = p.next -> after last -> head
pp.Next = elem; //p.next.element = x -> last -> next -> inserted_elem
elem.Next = temp; //p.next.next = temp -> inserted_elem -> head.
elem.Previous = pp;
temp.Previous = elem;
this._count += 1;
}
public override String ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append("[ ");
DoubleElementType <T> p = _head.Next;
while (p != _head)
{
sb.Append(p.Element.ToString() + " ");
p = p.Next;
}
sb.Append("]");
return(sb.ToString());
}
//TODO: Make traverse into two ways left->right, right->left.
public Int32 IndexOf(T item)
{
DoubleElementType <T> p = _head.Next;
Int32 idx = 1;
while (p != _head)
{
if (p.Element.Equals(item))
{
return(idx);
}
idx += 1;
p = p.Next;
}
return(-1);
}
//DELETE
public Boolean Remove(T item)
{
DoubleElementType <T> p = _head;
while (p.Next != _head)
{
if (p.Next.Element.Equals(item))
{
//p.Next = p.Next.Next;
p.Previous.Next = p.Next;
p.Next.Previous = p.Previous;
_count -= 1;
return(true);
}
p = p.Next;
}
return(false);
}
//COPY TO ARRAY(array)
public void CopyTo(T[] array, Int32 arrayIndex)
{
DoubleElementType <T> first = _head.Next;
if (arrayIndex < 0 || arrayIndex >= array.Length)
{
Console.WriteLine("arrayIndex is out of range");
return;
}
Int32 i = arrayIndex;
while (first != _head && i < array.Length)//THROW ArgumentException IF(array.Length - arrayIndex < Count)
{
array[i] = first.Element;
first = first.Next;
i += 1;
}
}
public void RemoveAt(Int32 p)
{
Int32 q = 1;
if (Count == 0)
{
return;
}
DoubleElementType <T> pp = _head;
while (q < p && pp.Next != _head)
{
pp = pp.Next;
q += 1;
}
pp.Previous.Next = pp.Next;
pp.Next.Previous = pp.Previous;
this._count -= 1;
}
//RETRIEVE.
public T this[Int32 index] {
get{
DoubleElementType <T> b = _head;
Int32 q = 0;
while (b.Next != _head && q < index)
{
q += 1;
b = b.Next;
}
return(b.Element);
}
set{
DoubleElementType <T> b = _head;
Int32 q = 0;
while (b.Next != _head && q < index)
{
q += 1;
b = b.Next;
}
b.Element = value;
}
}
public void SetBack()
{
_p = l._tail;
}
public void SetForward()
{
_p = l._head;
}
