private static TrackID?DescribeBranch(Junction.Branch startBranch)
{
if (descriptions.TryGetValue(startBranch, out var trackID))
{
return(trackID);
}
// Main.DebugLog($"Starting BFS at {startBranch.track.logicTrack.ID}");
var visited = new HashSet <RailTrack>();
var queue = new Queue <Junction.Branch>(GetNextBranches(startBranch));
Junction.Branch?branch;
while (queue.Count > 0)
{
branch = queue.Dequeue();
// Main.DebugLog($"Examining {branch}, track={branch.track}, logicTrack={branch.track.logicTrack}, ID={branch.track.logicTrack.ID}");
trackID = branch.track.logicTrack.ID;
if (!trackID.IsGeneric())
{
descriptions[startBranch] = trackID;
return(trackID);
}
// avoid cycles
if (visited.Contains(branch.track))
{
continue;
}
visited.Add(branch.track);
foreach (var next in GetNextBranches(branch))
{
queue.Enqueue(next);
}
}
// Main.DebugLog($"BFS ended without result");
descriptions[startBranch] = null;
// Main.DebugLog($"returning null");
return(null);
}
private static IEnumerable <Junction.Branch> GetNextBranches(Junction.Branch start) => (start.first ? start.track.GetAllOutBranches() : start.track.GetAllInBranches()) ?? Enumerable.Empty <Junction.Branch>();
