lib: move some examples/* into specific subdirectories of their lib

[nit.git] / lib / poset.nit

diff --git a/lib/poset.nit b/lib/poset.nit
index aea40bb..3149b21 100644 (file)
--- 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 +163,62 @@ class POSet[E: Object]
                if res != 0 then return res
                return elements[a].count <=> elements[b].count
        end
+
+       # Filter elements to return only the smallest ones
+       #
+       # ~~~
+       # var s = new POSet[String]
+       # s.add_edge("B", "A")
+       # s.add_edge("C", "A")
+       # s.add_edge("D", "B")
+       # s.add_edge("D", "C")
+       # assert s.select_smallest(["A", "B"]) == ["B"]
+       # assert s.select_smallest(["A", "B", "C"]) == ["B", "C"]
+       # assert s.select_smallest(["B", "C", "D"]) == ["D"]
+       # ~~~
+       fun select_smallest(elements: Collection[E]): Array[E]
+       do
+               var res = new Array[E]
+               for e in elements do
+                       for f in elements do
+                               if e == f then continue
+                               if has_edge(f, e) then continue label
+                       end
+                       res.add(e)
+               end label
+               return res
+       end
+
+       # ~~~
+       # var s = new POSet[String]
+       # s.add_edge("B", "A")
+       # s.add_edge("C", "A")
+       # s.add_edge("D", "B")
+       # s.add_edge("D", "C")
+       # assert s.select_greatest(["A", "B"]) == ["A"]
+       # assert s.select_greatest(["A", "B", "C"]) == ["A"]
+       # assert s.select_greatest(["B", "C", "D"]) == ["B", "C"]
+       # ~~~
+       # Filter elements to return only the greatest ones
+       fun select_greatest(elements: Collection[E]): Array[E]
+       do
+               var res = new Array[E]
+               for e in elements do
+                       for f in elements do
+                               if e == f then continue
+                               if has_edge(e, f) then continue label
+                       end
+                       res.add(e)
+               end label
+               return res
+       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 +286,20 @@ 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