+
+# Concerns ranking
+
+# Sort MConcerns based on the module importation hierarchy ranking
+# see also: `MConcern::concern_rank` and `MConcern::booster_rank`
+#
+# Comparison is made with the formula:
+#
+# ~~~nitish
+# a.concern_rank + a.booster_rank <=> b.concern_rank + b.booster_ran
+# ~~~
+#
+# If both `a` and `b` have the same ranking,
+# ordering is based on lexicographic comparison of `a.name` and `b.name`
+class MConcernRankSorter
+ super Comparator
+ redef type COMPARED: MConcern
+
+ redef fun compare(a, b) do
+ if a.concern_rank == b.concern_rank then
+ return a.name <=> b.name
+ end
+ return a.concern_rank + a.booster_rank <=> b.concern_rank + b.booster_rank
+ end
+end
+
+redef class MConcern
+
+ # Boost a MConcern rank
+ # see: `MConcernRankSorter`
+ # Use a positive booster to push down a result in the list
+ # A negative booster can be used to push up the result
+ var booster_rank: Int = 0 is writable
+
+ # Concern ranking used for ordering
+ # see: `MConcernRankSorter`
+ # Rank can be positive or negative
+ fun concern_rank: Int is abstract
+end
+
+redef class MPackage
+ redef var concern_rank is lazy do
+ var max = 0
+ for mgroup in mgroups do
+ var mmax = mgroup.concern_rank
+ if mmax > max then max = mmax
+ end
+ return max + 1
+ end
+end
+
+redef class MGroup
+ redef var concern_rank is lazy do
+ var max = 0
+ for mmodule in mmodules do
+ var mmax = mmodule.concern_rank
+ if mmax > max then max = mmax
+ end
+ return max + 1
+ end
+end
+
+redef class MModule
+ redef var concern_rank is lazy do
+ var max = 0
+ for p in in_importation.direct_greaters do
+ var pmax = p.concern_rank
+ if pmax > max then max = pmax
+ end
+ return max + 1
+ end
+end