/// <summary>
/// Initializes and resets.
/// </summary>
public void Initialize()
{
// algorithm always succeeds, it may be dealing with an empty network and there are no targets.
this.HasSucceeded = true;
// intialize dykstra data structures.
_visits = new HashSet <uint>();
_pointerHeap = new BinaryHeap <uint>();
_pathTree = new PathTree();
// initialize the edge enumerator.
_edgeEnumerator = _graph.GetEdgeEnumerator();
// queue source.
if (!_source.Edge1.IsNoEdge)
{
_pointerHeap.Push(_weightHandler.AddPathTree(_pathTree, _source.Edge1.Raw, _source.Weight1, uint.MaxValue), 0);
}
if (!_source.Edge2.IsNoEdge)
{
_pointerHeap.Push(_weightHandler.AddPathTree(_pathTree, _source.Edge2.Raw, _source.Weight2, uint.MaxValue), 0);
}
}
/// <summary>
/// Initializes and resets.
/// </summary>
public void Initialize()
{
// algorithm always succeeds, it may be dealing with an empty network and there are no targets.
this.HasSucceeded = true;
// intialize dykstra data structures.
_pointerHeap = new BinaryHeap <uint>();
_pathTree = new PathTree();
_visited = new HashSet <uint>();
// queue source.
if (_source.Vertex1 != Constants.NO_VERTEX)
{
_pointerHeap.Push(_weightHandler.AddPathTree(_pathTree, _source.Vertex1, _source.Weight1, uint.MaxValue), 0);
}
if (_source.Vertex2 != Constants.NO_VERTEX)
{
_pointerHeap.Push(_weightHandler.AddPathTree(_pathTree, _source.Vertex2, _source.Weight2, uint.MaxValue), 0);
}
// gets the edge enumerator.
_edgeEnumerator = _graph.GetEdgeEnumerator();
}
/// <summary>
/// Executes the actual run.
/// </summary>
protected override void DoRun(CancellationToken cancellationToken)
{
// keep settled vertices.
_pathTree = new PathTree();
// initialize the queues.
var forwardQueue = new BinaryHeap <uint>();
var backwardQueue = new BinaryHeap <uint>();
// queue sources.
if (_source.Vertex1 != Constants.NO_VERTEX)
{
forwardQueue.Push(_weightHandler.AddPathTree(_pathTree, _source.Vertex1, _source.Weight1, uint.MaxValue), 0);
}
if (_source.Vertex2 != Constants.NO_VERTEX)
{
forwardQueue.Push(_weightHandler.AddPathTree(_pathTree, _source.Vertex2, _source.Weight2, uint.MaxValue), 0);
}
// queue targets.
if (_target.Vertex1 != Constants.NO_VERTEX)
{
backwardQueue.Push(_weightHandler.AddPathTree(_pathTree, _target.Vertex1, _target.Weight1, uint.MaxValue), 0);
}
if (_target.Vertex2 != Constants.NO_VERTEX)
{
backwardQueue.Push(_weightHandler.AddPathTree(_pathTree, _target.Vertex2, _target.Weight2, uint.MaxValue), 0);
}
// update best with current visits.
_best = new Tuple <uint, uint, T>(uint.MaxValue, uint.MaxValue, _weightHandler.Infinite);
// calculate stopping conditions.
var queueBackwardWeight = backwardQueue.PeekWeight();
var queueForwardWeight = forwardQueue.PeekWeight();
while (true)
{ // keep looping until stopping conditions.
if (backwardQueue.Count == 0 && forwardQueue.Count == 0)
{ // stop the search; both queues are empty.
break;
}
var bestItem2 = _weightHandler.GetMetric(_best.Item3);
if (bestItem2 < queueForwardWeight && bestItem2 < queueBackwardWeight)
{ // stop the search: it now became impossible to find a shorter route by further searching.
break;
}
// do a forward search.
if (forwardQueue.Count > 0)
{ // first check for better path.
// get the current queued with the smallest weight that hasn't been visited yet.
var cPointer = forwardQueue.Pop();
uint cVertex, cPreviousPointer;
T cWeight;
_weightHandler.GetPathTree(_pathTree, cPointer, out cVertex, out cWeight, out cPreviousPointer);
while (_forwardVisits.ContainsKey(cVertex))
{ // keep trying.
if (forwardQueue.Count == 0)
{
cPointer = uint.MaxValue;
}
else
{
cPointer = forwardQueue.Pop();
_weightHandler.GetPathTree(_pathTree, cPointer, out cVertex, out cWeight, out cPreviousPointer);
}
}
if (cPointer != uint.MaxValue)
{
uint bPointer;
if (_backwardVisits.TryGetValue(cVertex, out bPointer))
{ // check for a new best.
uint bVertex, bPreviousPointer;
T bWeight;
_weightHandler.GetPathTree(_pathTree, bPointer, out bVertex, out bWeight, out bPreviousPointer);
var total = _weightHandler.Add(cWeight, bWeight);
if (_weightHandler.IsSmallerThan(total, _best.Item2))
{ // a better path was found.
_best = new Tuple <uint, uint, T>(cPointer, bPointer, total);
this.HasSucceeded = true;
}
}
this.SearchForward(forwardQueue, cPointer, cVertex, cWeight);
}
}
// do a backward search.
if (backwardQueue.Count > 0)
{// first check for better path.
// get the current queued with the smallest weight that hasn't been visited yet.
var cPointer = backwardQueue.Pop();
uint cVertex, cPreviousPointer;
T cWeight;
_weightHandler.GetPathTree(_pathTree, cPointer, out cVertex, out cWeight, out cPreviousPointer);
while (_backwardVisits.ContainsKey(cVertex))
{ // keep trying.
if (backwardQueue.Count == 0)
{
cPointer = uint.MaxValue;
}
else
{
cPointer = backwardQueue.Pop();
_weightHandler.GetPathTree(_pathTree, cPointer, out cVertex, out cWeight, out cPreviousPointer);
}
}
if (cPointer != uint.MaxValue)
{
uint bPointer; // best pointer.
if (_forwardVisits.TryGetValue(cVertex, out bPointer))
{ // check for a new best.
uint bVertex, bPreviousPointer;
T bWeight;
_weightHandler.GetPathTree(_pathTree, bPointer, out bVertex, out bWeight, out bPreviousPointer);
var total = _weightHandler.Add(cWeight, bWeight);
if (_weightHandler.IsSmallerThan(total, _best.Item2))
{ // a better path was found.
_best = new Tuple <uint, uint, T>(bPointer, cPointer, total);
this.HasSucceeded = true;
}
}
this.SearchBackward(backwardQueue, cPointer, cVertex, cWeight);
}
}
// calculate stopping conditions.
if (forwardQueue.Count > 0)
{
queueForwardWeight = forwardQueue.PeekWeight();
}
if (backwardQueue.Count > 0)
{
queueBackwardWeight = backwardQueue.PeekWeight();
}
}
}
