/// <summary>
/// Scans the specified graph, using recursion, and produces SCC results.
/// </summary>
/// <param name="graph">The graph to search.</param>
/// <param name="vertex">The current vertex to scan and connect.</param>
/// <param name="weigher">The optional weigher to use.</param>
/// <param name="result">The graph search result.</param>
/// <returns>Augmentation vertex data for the current vertex.</returns>
private VertexData Connect(IGraph <V, E> graph, V vertex, IEdgeWeigher <V, E> weigher, SccResult result)
{
VertexData data = result.AddData(vertex);
// Scan through all egress edges of the current vertex.
foreach (E edge in graph.GetEdgesFrom(vertex))
{
V nextVertex = edge.Dst;
// If edge is not viable, skip it.
if (weigher != null && !weigher.GetWeight(edge).IsViable)
{
continue;
}
// Attempt to get the augmentation vertex data for the next vertex.
VertexData nextData = result.GetData(nextVertex);
if (nextData is null)
{
// Next vertex has not been visited yet, so do this now.
nextData = Connect(graph, nextVertex, weigher, result);
data.LowLink = Math.Min(data.LowLink, nextData.LowLink);
}
else if (result.Visited(nextData))
{
// Next vertex has been visited, which means
// it is in the same cluster as the current vertex.
data.LowLink = Math.Min(data.LowLink, nextData.Index);
}
}
if (data.LowLink == data.Index)
{
result.AddCluster(data);
}
return(data);
}
/// <summary> /// Determines whether the given vertex has been visited. /// </summary> /// <param name="data">The vertex to check.</param> /// <returns>True if the vertex has been visited, otherwise false.</returns> internal bool Visited(VertexData data) => visited.Contains(data);
