public void AddDocument(Document d)
{
// Contract.Requires<ArgumentNullException>(d != null, "argument d must not be null");
// if (d == null) throw new ArgumentNullException("d");
AddDocumentToPriorityNode(d, d.Priority);
}
private void AddDocumentToPriorityNode(Document doc, int priority)
{
// Contract.Requires<ArgumentException>(priority >= 0 && priority < 10, "priority value must be between 0 and 9");
//if (priority > 9 || priority < 0)
// throw new ArgumentException("Priority must be between 0 and 9");
if (_priorityNodes[priority].Value == null)
{
--priority;
if (priority >= 0)
{
// check for the next lower priority
AddDocumentToPriorityNode(doc, priority);
}
else // now no priority node exists with the same priority or lower
// add the new document to the end
{
_documentList.AddLast(doc);
_priorityNodes[doc.Priority] = _documentList.Last;
}
return;
}
else // a priority node exists
{
LinkedListNode<Document> prioNode = _priorityNodes[priority];
if (priority == doc.Priority)
// priority node with the same priority exists
{
_documentList.AddAfter(prioNode, doc);
// set the priority node to the last document with the same priority
_priorityNodes[doc.Priority] = prioNode.Next;
}
else // only priority node with a lower priority exists
{
// get the first node of the lower priority
LinkedListNode<Document> firstPrioNode = prioNode;
while (firstPrioNode.Previous != null &&
firstPrioNode.Previous.Value.Priority == prioNode.Value.Priority)
{
firstPrioNode = prioNode.Previous;
prioNode = firstPrioNode;
}
_documentList.AddBefore(firstPrioNode, doc);
// set the priority node to the new value
_priorityNodes[doc.Priority] = firstPrioNode.Previous;
}
}
}