private void ScanInternal()
{
while (frontier.Count > 0)
{
Point current = frontier.Dequeue();
foreach (Dir8 dir in EightDirections.Enumerate(true, false, false))
{
Point neighbor = current.PointInDir(dir);
if (!neighbor.ExistsOnMap())
{
continue;
}
int neighborCost = GetCellCost(neighbor);
if (neighborCost < 0)
{
if (this[neighbor] == Unexplored)
{
this[neighbor] = Blocked;
}
}
else
{
int totalCost = this[current] + neighborCost;
if (this[neighbor] > totalCost)
{
this[neighbor] = totalCost;
frontier.Enqueue(neighbor, totalCost);
}
}
}
}
}
public static IEnumerable <Point> GetNeighbors(this Point source)
{
foreach (Dir8 dir in EightDirections.Enumerate(true, false, false))
{
yield return(source.PointInDir(dir));
}
}
public static IEnumerable <Point> Scan(Point source, Func <Point, bool> condition, SourceOption sourceOption = SourceOption.AlwaysIncludeSource)
{
List <Point> frontier = new List <Point>();
HashSet <Point> visited = new HashSet <Point> {
source
};
switch (sourceOption)
{
case SourceOption.AlwaysIncludeSource:
yield return(source);
break;
case SourceOption.ConditionallyIncludeSource:
case SourceOption.StopScanOnSourceFailure:
if (condition.Invoke(source))
{
yield return(source);
}
else if (sourceOption == SourceOption.StopScanOnSourceFailure)
{
yield break;
}
break;
}
frontier.Add(source);
while (frontier.Count > 0)
{
Point current = frontier[frontier.Count - 1];
frontier.RemoveAt(frontier.Count - 1);
foreach (Dir8 dir in EightDirections.Enumerate(true, false, false))
{
Point neighbor = current.PointInDir(dir);
if (!neighbor.ExistsBetweenMapEdges())
{
continue;
}
if (visited.Contains(neighbor))
{
continue;
}
if (condition.Invoke(neighbor))
{
yield return(neighbor);
frontier.Add(neighbor);
visited.Add(neighbor);
}
}
}
}
/* Might add these at some point -- these are the ones that would allow partial rescans by resetting values starting at the changed cell(s).
* 1) Search outward from the given changed cell(s) as long as you can keep jumping to a cell with HIGHER total cost. This set of cells represents
* all the cells which might have been influenced by the changed cell(s).
* 2) Note where this search stopped: Each of the cells adjacent to this set (but not part of it) will be the frontier for the rescan.
* 3) Reset the value of each cell in this set to Unexplored.
* 3) Rescan the map from the frontier.
* (If any of the changed cells could be sources, that needs to be handled too.)
* public void Rescan(Point changedCell){ }
* public void Rescan(IEnumerable<Point> changedCells){ }*/
private void RescanInternal() // Differs from ScanInternal in how it uses the frontier
{
while (frontier.Count > 0)
{
Point current = frontier.Dequeue();
foreach (Dir8 dir in EightDirections.Enumerate(true, false, false))
{
Point neighbor = current.PointInDir(dir);
if (!neighbor.ExistsOnMap())
{
continue;
}
if (this[neighbor] == Blocked)
{
continue;
}
int neighborCost = GetCellCost(neighbor);
if (neighborCost < 0)
{
if (this[neighbor] == Unexplored)
{
frontier.TryRemove(neighbor); // (Not sure this can happen on a rescan if done correctly)
this[neighbor] = Blocked;
}
}
else
{
int totalCost = this[current] + neighborCost;
if (this[neighbor] > totalCost)
{
// Remove them before changing sort values, so the sort doesn't break:
if (this[neighbor] != Unexplored)
{
frontier.TryRemove(neighbor);
}
this[neighbor] = totalCost;
frontier.Enqueue(neighbor, totalCost);
}
}
}
}
}
