Check for bad edge direction and abort path

HexGrid/Path.pm

@@ -1,3 +1,7 @@
+=head1 HexGrid::Path
+
+=cut
+
 package HexGrid::Path;
 
 use v5.30;
@@ -34,14 +38,12 @@ sub get_edge_direction($tile1, $tile2)
 	return $HexGrid::DIR{ne} if $nw_diff ==  0 && $sw_diff == -1;
 	return $HexGrid::DIR{n}  if $nw_diff ==  1 && $sw_diff == -1;
 
-	#TODO: render and splinter should check this returns successfully;
 	carp("Tiles are not adjacent: " . $tile1->nw . "," . $tile1->sw . "—"
 		. $tile2->nw . "," . $tile2->sw);
 	return undef;
 }
 
 
-
 # Instance
 
 sub clone_settings($this)
@@ -90,7 +92,13 @@ sub splinter($this, $grid)
 				# Don't set source on first tile
 				if($i >= 1)
 				{
-					$splinter->{starts_from} = get_edge_direction($this->{tiles}[$i], $this->{tiles}[$i-1]);
+					my $starting_edge = get_edge_direction($this->{tiles}[$i], $this->{tiles}[$i-1]);
+					unless($starting_edge)
+					{
+						carp("Path " . $this->{id} . " has non-adjacent edges, aborting.");
+						return;
+					}
+					$splinter->{starts_from} = $starting_edge;
 				}
 				push @{$splinter->tiles}, $this->{tiles}[$i];
 				push @splinters, $splinter;
@@ -108,8 +116,14 @@ sub splinter($this, $grid)
 			{
 				# In a splinter but tile not present, set previous tile sink to this missing tile
 				$in_splinter = 0;
-				$splinters[$#splinters]{ends_to} =
-					get_edge_direction($this->{tiles}[$i-1], $this->{tiles}[$i]);
+				my $ending_edge = get_edge_direction($this->{tiles}[$i-1], $this->{tiles}[$i]);
+				unless($ending_edge)
+				{
+					carp("Path " . $this->{id} . " has non-adjacent edges, aborting.");
+					return;
+				}
+				$splinters[$#splinters]{ends_to} = $ending_edge;
+					
 			}
 		}
 	}
@@ -178,6 +192,11 @@ sub render($this, $grid, $svg)
 	my $previous_tile = $current_tile;
 	$current_tile = shift @tiles;
 	my $next_edge = get_edge_direction($previous_tile, $current_tile);
+	unless($next_edge)
+	{
+		carp("Path " . $this->{id} . " has non-adjacent edges, aborting.");
+		return;
+	}
 	($x, $y) = $grid->coords_of_edge($previous_tile->nw, $previous_tile->sw, $next_edge);
 	if($this->starts_from)
 	{
@@ -199,6 +218,11 @@ sub render($this, $grid, $svg)
 		$next_tile = shift @tiles;
 		$previous_edge = -$next_edge;
 		$next_edge = get_edge_direction($current_tile, $next_tile);
+		unless($next_edge)
+		{
+			carp("Path " . $this->{id} . " has non-adjacent edges, aborting.");
+			return;
+		}
 
 		my ($qx,$qy) = $grid->coords_of_centre($current_tile->nw, $current_tile->sw);
 		($x,$y) = $grid->coords_of_edge($current_tile->nw, $current_tile->sw, $next_edge);
@@ -228,4 +252,8 @@ sub render($this, $grid, $svg)
 	return $g;
 }
 
+=back
+
+=cut
+
 1;