public RouteFinderLists Open(LocationCandiate candiate)
{
var existing = _openList.Lookup(candiate.Location);
return(existing
.Select(x => x.CurrentCost < candiate.CurrentCost)
.OrElse(false)
? this
: new RouteFinderLists(
_openList.SetItem(candiate.Location, candiate),
_closedList));
}
public static Path BuildActorPath(LocationCandiate targetCandidate)
{
// Do not expect one node, would mean start = end
Debug.Assert(targetCandidate.Parent.HasValue);
// Pop last location added as it will be the current location
return(Path.Create(
targetCandidate.Location,
targetCandidate
.LinkedListToEnumerable(node => node.Parent)
.Aggregate(
ImmutableStack <Vector> .Empty,
(stack, candidate) => stack.Push(candidate.Location))
.Pop()));
}
public static RouteFinderLists OpenCandidateMoves(
RouteFinderLists lists,
LocationCandiate currentNode,
Vector target,
Func <Vector, bool> isValidMove)
{
Func <Vector, bool> isViable =
move => isValidMove(move) && !lists.IsClosed(move);
return(currentNode.Location
.GetValidMoves(isViable)
.Select(move => LocationCandiate
.Create(target, move, currentNode.ToSome()))
.Aggregate(
lists.Close(currentNode),
(finderLists, candiate) => finderLists.Open(candiate)));
}
public static IMaybe <Path> FindRoute(
this Vector start, Vector target,
Func <Vector, bool> isValidMove,
IMaybe <int> breakSize)
{
Debug.Assert(isValidMove != null);
if (start == target)
{
return(Maybe <Path> .None);
}
var lists = RouteFinderLists
.Create()
.Open(LocationCandiate.Create(target, start));
while (lists.HasOpenCandidates)
{
// Capture to stop access modified closure
var closedList = lists.ClosedList;
if (breakSize.Select(x => x < closedList.Count).OrElse(false))
{
break;
}
var currentNode = lists.NextOpenCandiate;
if (currentNode.Location == target)
{
return(BuildActorPath(currentNode).ToSome());
}
lists = OpenCandidateMoves(
lists, currentNode, target, isValidMove);
}
return(Maybe <Path> .None);
}
public RouteFinderLists Close(LocationCandiate candidate)
{
return(new RouteFinderLists(
_openList.Remove(candidate.Location),
_closedList.SetItem(candidate.Location, candidate)));
}