public void Enqueue(string word, double priority)
{
if (_numNodes >= _nodes.Length - 1)
{
if (priority > First.Similarity)
{
Dequeue();
_extras.Clear();
}
else if (priority + 0.0000000001 > First.Similarity)
{
_extras.Add(new WordSimilarityNode {
Similarity = priority, Word = word
});
return;
}
else
{
return;
}
}
var node = new WordSimilarityNode {
Similarity = priority, Word = word
};
_numNodes++;
_nodes[_numNodes] = node;
node.QueueIndex = _numNodes;
CascadeUp(_nodes[_numNodes]);
}
private void CascadeDown(WordSimilarityNode node)
{
//aka Heapify-down
var finalQueueIndex = node.QueueIndex;
while (true)
{
var newParent = node;
var childLeftIndex = 2 * finalQueueIndex;
//Check if the left-child is higher-priority than the current node
if (childLeftIndex > _numNodes)
{
//This could be placed outside the loop, but then we'd have to check newParent != node twice
node.QueueIndex = finalQueueIndex;
_nodes[finalQueueIndex] = node;
break;
}
var childLeft = _nodes[childLeftIndex];
if (childLeft.Similarity < newParent.Similarity)
{
newParent = childLeft;
}
//Check if the right-child is higher-priority than either the current node or the left child
var childRightIndex = childLeftIndex + 1;
if (childRightIndex <= _numNodes)
{
var childRight = _nodes[childRightIndex];
if (childRight.Similarity < newParent.Similarity)
{
newParent = childRight;
}
}
//If either of the children has higher (smaller) priority, swap and continue cascading
if (newParent != node)
{
//Move new parent to its new index. node will be moved once, at the end
//Doing it this way is one less assignment operation than calling Swap()
_nodes[finalQueueIndex] = newParent;
var temp = newParent.QueueIndex;
newParent.QueueIndex = finalQueueIndex;
finalQueueIndex = temp;
}
else
{
//See note above
node.QueueIndex = finalQueueIndex;
_nodes[finalQueueIndex] = node;
break;
}
}
}
private void Swap(WordSimilarityNode node1, WordSimilarityNode node2)
{
//Swap the nodes
_nodes[node1.QueueIndex] = node2;
_nodes[node2.QueueIndex] = node1;
//Swap their indicies
var temp = node1.QueueIndex;
node1.QueueIndex = node2.QueueIndex;
node2.QueueIndex = temp;
}
//Performance appears to be slightly better when this is NOT inlined o_O
private void CascadeUp(WordSimilarityNode node)
{
//aka Heapify-up
var parent = node.QueueIndex / 2;
while (parent >= 1)
{
var parentNode = _nodes[parent];
if (parentNode.Similarity < node.Similarity)
{
break;
}
//Node has lower priority value, so move it up the heap
Swap(node, parentNode); //For some reason, this is faster with Swap() rather than (less..?) individual operations, like in CascadeDown()
parent = node.QueueIndex / 2;
}
}