X-Git-Url: http://nitlanguage.org

diff --git a/lib/a_star.nit b/lib/a_star.nit
index 9780e12..cc0cba3 100644
--- a/lib/a_star.nit
+++ b/lib/a_star.nit
@@ -14,9 +14,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Services related to pathfinding of graphs using A*
-# A single graph may have different properties according to the `PathContext` used
+# A* pathfinding in graphs
 #
+# A single graph may have different properties according to the `PathContext` used
 #
 # Usage:
 #
@@ -188,13 +188,21 @@ class Node
 		end
 	end
 
+	# Find the closest node accepted by `cond` under `max_cost`
+	fun find_closest(max_cost: Int, context: PathContext, cond: nullable TargetCondition[N]): nullable N
+	do
+		var path = path_to_alts(null, max_cost, context, cond)
+		if path == null then return null
+		return path.nodes.last
+	end
+
 	# We customize the serialization process to avoid problems with recursive
 	# serialization engines. These engines, such as `JsonSerializer`,
 	# are at danger to serialize the graph as a very deep tree.
 	# With a large graph it can cause a stack overflow.
 	#
 	# Instead, we serialize the nodes first and then the links.
-	redef fun core_serialize_to(serializer: Serializer)
+	redef fun core_serialize_to(serializer)
 	do
 		serializer.serialize_attribute("graph", graph)
 	end
@@ -265,7 +273,7 @@ class Graph[N: Node, L: Link]
 	# Used to check if nodes have been searched in one pathfinding
 	private var pathfinding_current_evocation: Int = 0
 
-	redef fun core_serialize_to(serializer: Serializer)
+	redef fun core_serialize_to(serializer)
 	do
 		serializer.serialize_attribute("nodes", nodes)
 		serializer.serialize_attribute("links", links)
@@ -316,7 +324,7 @@ class AStarPath[N]
 end
 
 # Context related to an evocation of pathfinding
-class PathContext
+abstract class PathContext
 	serialize
 
 	# Type of the nodes in `graph`
@@ -380,7 +388,7 @@ class WeightedPathContext
 		self.worst_cost = worst_cost
 	end
 
-	redef var worst_cost: Int is noinit
+	redef var worst_cost is noinit
 
 	redef fun cost(l) do
 		return l.weight
@@ -400,7 +408,7 @@ class WeightedLink
 end
 
 # Advanced path conditions with customizable accept states
-class TargetCondition[N: Node]
+abstract class TargetCondition[N: Node]
 	serialize
 
 	# Should the pathfinding accept `node` as a goal?