public void RemoveItem(PriorityItem <T> item)
{
PriorityChain <T> chain = item.Chain;
this.RemoveItemFromPriorityChain(item);
this.RemoveItemFromSequentialChain(item);
}
public void ChangeItemPriority(PriorityItem <T> item, double priority)
{
this.RemoveItemFromPriorityChain(item);
PriorityChain <T> chain = this.GetChain(priority);
this.InsertItemInPriorityChain(item, chain);
}
// Methods
public PriorityQueue()
{
this._priorityChains = new SortedList <int, PriorityChain <T> >();
this._cacheReusableChains = new Stack <PriorityChain <T> >(10);
this._head = (PriorityItem <T>)(this._tail = null);
this._count = 0;
}
internal void InsertItemInSequentialChain(PriorityItem <T> item, PriorityItem <T> after)
{
if (after == null)
{
if (this._head != null)
{
this._head.SequentialPrev = item;
item.SequentialNext = this._head;
this._head = item;
}
else
{
this._head = this._tail = item;
}
}
else
{
item.SequentialPrev = after;
if (after.SequentialNext != null)
{
item.SequentialNext = after.SequentialNext;
after.SequentialNext.SequentialPrev = item;
after.SequentialNext = item;
}
else
{
after.SequentialNext = item;
this._tail = item;
}
}
this._count++;
}
internal void InsertItemInPriorityChain(PriorityItem <T> item, PriorityChain <T> chain, PriorityItem <T> after)
{
item.Chain = chain;
if (after == null)
{
if (chain.Head != null)
{
chain.Head.PriorityPrev = item;
item.PriorityNext = chain.Head;
chain.Head = item;
}
else
{
chain.Head = chain.Tail = item;
}
}
else
{
item.PriorityPrev = after;
if (after.PriorityNext != null)
{
item.PriorityNext = after.PriorityNext;
after.PriorityNext.PriorityPrev = item;
after.PriorityNext = item;
}
else
{
after.PriorityNext = item;
chain.Tail = item;
}
}
chain.Count++;
}
public PriorityItem <T> Enqueue(double priority, T data)
{
PriorityChain <T> chain = this.GetChain(priority);
PriorityItem <T> item = new PriorityItem <T>(data);
this.InsertItemInSequentialChain(item, this._tail);
this.InsertItemInPriorityChain(item, chain, chain.Tail);
return(item);
}
public T Dequeue()
{
int count = this._priorityChains.Count;
if (count <= 0)
{
throw new InvalidOperationException();
}
PriorityChain <T> chain = this._priorityChains.Values[count - 1];
PriorityItem <T> head = chain.Head;
this.RemoveItem(head);
return(head.Data);
}
private void InsertItemInPriorityChain(PriorityItem <T> item, PriorityChain <T> chain)
{
if (chain.Head == null)
{
this.InsertItemInPriorityChain(item, chain, null);
}
else
{
PriorityItem <T> after = null;
after = item.SequentialPrev;
while (after != null)
{
if (after.Chain == chain)
{
break;
}
after = after.SequentialPrev;
}
this.InsertItemInPriorityChain(item, chain, after);
}
}
private void RemoveItemFromSequentialChain(PriorityItem <T> item)
{
if (item.SequentialPrev != null)
{
item.SequentialPrev.SequentialNext = item.SequentialNext;
}
else
{
this._head = item.SequentialNext;
}
if (item.SequentialNext != null)
{
item.SequentialNext.SequentialPrev = item.SequentialPrev;
}
else
{
this._tail = item.SequentialPrev;
}
item.SequentialPrev = (PriorityItem <T>)(item.SequentialNext = null);
this._count--;
}
private void RemoveItemFromPriorityChain(PriorityItem <T> item)
{
if (item.PriorityPrev != null)
{
item.PriorityPrev.PriorityNext = item.PriorityNext;
}
else
{
item.Chain.Head = item.PriorityNext;
}
if (item.PriorityNext != null)
{
item.PriorityNext.PriorityPrev = item.PriorityPrev;
}
else
{
item.Chain.Tail = item.PriorityPrev;
}
item.PriorityPrev = (PriorityItem <T>)(item.PriorityNext = null);
PriorityChain <T> chain = item.Chain;
chain.Count--;
if (item.Chain.Count == 0)
{
if (item.Chain.Priority == this._priorityChains.Keys[this._priorityChains.Count - 1])
{
this._priorityChains.RemoveAt(this._priorityChains.Count - 1);
}
else
{
this._priorityChains.Remove((int)item.Chain.Priority);
}
if (this._cacheReusableChains.Count < 10)
{
item.Chain.Priority = -1;//DispatcherPriority.Invalid;
this._cacheReusableChains.Push(item.Chain);
}
}
item.Chain = null;
}
