public bool TryDequeue(out PriorityQueueItem <TValue, TPriority> value)
{
value = new PriorityQueueItem <TValue, TPriority>();
if (Count == 0)
{
return(false);
}
value = RemoveAt(0);
return(true);
}
private PriorityQueueItem <TValue, TPriority> RemoveAt(Int32 index)
{
PriorityQueueItem <TValue, TPriority> o = items[index];
--numItems;
// move the last item to fill the hole
PriorityQueueItem <TValue, TPriority> tmp = items[numItems];
// If you forget to clear this, you have a potential memory leak.
items[numItems] = default(PriorityQueueItem <TValue, TPriority>);
if (numItems > 0 && index != numItems)
{
// If the new item is greater than its parent, bubble up.
int i = index;
int parent = (i - 1) / 2;
while (compareFunc(tmp.Priority, items[parent].Priority) > 0)
{
items[i] = items[parent];
i = parent;
parent = (i - 1) / 2;
}
// if i == index, then we didn't move the item up
if (i == index)
{
// bubble down ...
while (i < (numItems) / 2)
{
int j = (2 * i) + 1;
if ((j < numItems - 1) && (compareFunc(items[j].Priority, items[j + 1].Priority) < 0))
{
++j;
}
if (compareFunc(items[j].Priority, tmp.Priority) <= 0)
{
break;
}
items[i] = items[j];
i = j;
}
}
// Be sure to store the item in its place.
items[i] = tmp;
}
//if (!VerifyQueue())
//{
// Console.WriteLine("ERROR: Queue out of order!");
//}
return(o);
}
public void Enqueue(PriorityQueueItem <TValue, TPriority> newItem)
{
if (numItems == capacity)
{
// need to increase capacity
// grow by 50 percent
SetCapacity((3 * Capacity) / 2);
}
int i = numItems;
++numItems;
while ((i > 0) && (compareFunc(items[(i - 1) / 2].Priority, newItem.Priority) < 0))
{
items[i] = items[(i - 1) / 2];
i = (i - 1) / 2;
}
items[i] = newItem;
//if (!VerifyQueue())
//{
// Console.WriteLine("ERROR: Queue out of order!");
//}
}