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

diff --git a/lib/poset.nit b/lib/poset.nit
index aea40bb..ac0765e 100644
--- a/lib/poset.nit
+++ b/lib/poset.nit
@@ -24,7 +24,7 @@ module poset
 #  * transitivity: `(self.has_edge(e,f) and self.has_edge(f,g)) implies self.has_edge(e,g)`
 class POSet[E: Object]
 	super Collection[E]
-	super AbstractSorter[E]
+	super Comparator[E]
 
 	redef fun iterator do return elements.keys.iterator
 
@@ -163,6 +163,13 @@ class POSet[E: Object]
 		if res != 0 then return res
 		return elements[a].count <=> elements[b].count
 	end
+
+	# Sort a sorted array of poset elements using linearization order
+	fun linearize(elements: Collection[E]): Array[E] do
+		var lin = elements.to_a
+		sort(lin)
+		return lin
+	end
 end
 
 # View of an objet in a poset
@@ -230,4 +237,20 @@ class POSetElement[E: Object]
 	do
 		return t != self.element and self.tos.has(t)
 	end
+
+	# The length of the shortest path to the root of the poset hierarchy
+	fun depth: Int do
+		if direct_greaters.is_empty then
+			return 0
+		end
+		var min = -1
+		for p in direct_greaters do
+			var d = poset[p].depth + 1
+			if min == -1 or d < min then
+				min = d
+			end
+		end
+		return min
+
+	end
 end