//вставить элемент перед элементом с указанным индексом
//если элемента нет - вставить в конец
public void Insert(IListItem item, int index)
{
if (index < 0)
{
return;
}
if (index == 0)
{
AddFirst(item);
return;
}
IListItem CurrItem = ListHead;
for (int i = 0; i < index - 1; i++)
{
CurrItem = CurrItem.Next();
}
if ((CurrItem == null) || (CurrItem.Next() == null))
{
AddLast(item);
return;
}
ListItem NewItem = new ListItem(item.Value, CurrItem);
NewItem.NextElem = CurrItem.Next();
ListItem PrevItem = CurrItem as ListItem;
ListItem NextItem = CurrItem.Next() as ListItem;
PrevItem.NextElem = NewItem;
NextItem.PrevElem = NewItem;
}
//сортировка списка в обратном порядке
public void Reverse()
{
IListItem CurrItem = ListHead;
while (CurrItem != null)
{
ListItem item = CurrItem as ListItem;
IListItem Temp = item.NextElem;
item.NextElem = item.PrevElem;
item.PrevElem = Temp;
if (CurrItem.Next() == null)
{
ListHead = CurrItem as ListItem;
}
CurrItem = CurrItem.Next();
}
}
//добавить элемент в конец
public void AddLast(IListItem item)
{
if (ListHead == null)
{
ListHead = new ListItem(item.Value);
}
else
{
IListItem CurrItem = ListHead;
while (CurrItem != null)
{
if (CurrItem.Next() == null)
{
ListItem NewItem = new ListItem(item.Value, CurrItem);
ListItem Item = CurrItem as ListItem;
Item.NextElem = NewItem;
}
CurrItem = CurrItem.Next();
}
}
}
//вернуть все элементы списка, кроме первого
public IEnumerable <IListItem> GetAll()
{
List <IListItem> Items = new List <IListItem>();
IListItem CurrItem = ListHead;
while (CurrItem != null)
{
Items.Add(CurrItem);
CurrItem = CurrItem.Next();
}
return(Items);
}