public void Clear()
{
lock (this)
{
first = null;
last = null;
current = null;
}
}
public bool MoveDown(object v)
{
bool bRet = false;
clsListItem obj = first;
clsListItem prev, next;
while (obj != null)
{
if (obj.obj == v)
{
if (obj == last)
{
break;
}
current = obj;
prev = obj.prev;
next = obj.next;
//
if (next.next == null)
{
//move to the last
last = obj;
obj.next = null;
obj.prev = next;
next.next = obj;
}
else
{
next.next.prev = obj;
obj.next = next.next;
obj.prev = next;
next.next = obj;
}
next.prev = prev;
if (prev == null)
{
first = next;
}
else
{
prev.next = next;
}
return(true);
}
obj = obj.next;
}
return(bRet);
}
public bool setCurrent(object v)
{
bool bRet = false;
clsListItem obj = first;
while (obj != null)
{
if (obj.obj == v)
{
current = obj;
return(true);
}
obj = obj.next;
}
return(bRet);
}
public virtual object PopFirst()
{
lock (this)
{
if (first != null)
{
object v = first.obj;
first = first.next;
if (first != null)
{
first.prev = null;
}
current = first;
return(v);
}
return(null);
}
}
public virtual void Add(object obj)
{
lock (this)
{
if (first == null || last == null)
{
first = new clsListItem(obj);
last = first;
current = first;
}
else
{
current = new clsListItem(obj);
current.prev = last;
last.next = current;
last = current;
}
}
}
/// <summary>
/// calling function should place lock to ensure thread-safe
/// </summary>
public void DeleteCurrent()
{
if (current != null)
{
if (current.prev == null)
{
//it is the first
first = current.next;
if (first == null)
{
last = null;
}
else
{
first.prev = null;
}
current = first;
}
else
{
if (current.next == null)
{
//it is the last
last = current.prev;
current = last;
current.next = null;
}
else
{
//first and last will not change
//connect prev and next together.
//current.prev ->current ->current.next
current.next.prev = current.prev;
current.prev.next = current.next;
current = current.next;
}
}
}
}
