/// <summary>
/// Called when a vertex was reached during a forward search.
/// </summary>
/// <returns></returns>
private bool ReachedForward(EdgePath <T> forwardVisit)
{
// check backward search for the same vertex.
EdgePath <T> backwardVisit;
if (_targetSearch.TryGetVisit(-forwardVisit.Edge, out backwardVisit))
{ // there is a status for this edge in the target search.
var localWeight = _weightHandler.Zero;
if (forwardVisit.From != null)
{
localWeight = _weightHandler.Subtract(forwardVisit.Weight, forwardVisit.From.Weight);
}
var totalWeight = _weightHandler.Subtract(_weightHandler.Add(forwardVisit.Weight, backwardVisit.Weight), localWeight);
if (_weightHandler.IsSmallerThan(totalWeight, _best.Item3))
{ // this is a better match.
if (forwardVisit.Vertex == backwardVisit.From.Vertex &&
(forwardVisit.From.From != null || backwardVisit.From.From != null))
{ // paths match and are bigger than one edge.
_best = new Tuple <EdgePath <T>, EdgePath <T>, T>(forwardVisit, backwardVisit, totalWeight);
this.HasSucceeded = true;
}
}
}
return(false);
}
/// <summary>
/// Called when a vertex was reached during a backward search.
/// </summary>
/// <returns></returns>
private bool ReachedBackward(uint vertex1, T weight1, float length, EdgePath <T> edge)
{
// check forward search for the same vertex.
EdgePath <T> forwardVisit;
if (_sourceSearch.TryGetVisit(-edge.Edge, out forwardVisit))
{ // there is a status for this vertex in the source search.
var localWeight = _weightHandler.Subtract(edge.Weight, weight1);
var totalWeight = _weightHandler.Subtract(_weightHandler.Add(edge.Weight, forwardVisit.Weight), localWeight);
if (_weightHandler.IsSmallerThan(totalWeight, _best.Item3))
{ // this vertex is a better match.
_best = new Tuple <EdgePath <T>, EdgePath <T>, T>(forwardVisit, edge, totalWeight);
this.HasSucceeded = true;
}
}
return(false);
}
/// <summary>
/// Appends the given path in reverse to the edge path.
/// </summary>
public static EdgePath <T> Append <T>(this EdgePath <T> path, EdgePath <T> reversePath, WeightHandler <T> weightHandler)
where T : struct
{
if (path.Vertex != reversePath.Vertex)
{
throw new System.Exception("Cannot append path that ends with a different vertex.");
}
while (reversePath.From != null)
{
var localWeight = weightHandler.Subtract(reversePath.Weight, reversePath.From.Weight);
path = new EdgePath <T>(reversePath.From.Vertex, weightHandler.Add(path.Weight, localWeight), -reversePath.Edge, path);
reversePath = reversePath.From;
}
return(path);
}
