X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Futils%2FDigraph.lhs;h=1544c7b93386c90f15fd4ae646a73bbe99ea8215;hb=d923f167d8a1120c0e918330b44740f8f12b7f45;hp=f09d465bc259cdb65a0d5d40e0365d4e821b8db4;hpb=6c393867f02f2f7482a0431d4abb8d998ef88dc5;p=ghc-hetmet.git

diff --git a/ghc/compiler/utils/Digraph.lhs b/ghc/compiler/utils/Digraph.lhs
index f09d465..1544c7b 100644
--- a/ghc/compiler/utils/Digraph.lhs
+++ b/ghc/compiler/utils/Digraph.lhs
@@ -2,7 +2,7 @@
 module Digraph(
 
 	-- At present the only one with a "nice" external interface
-	stronglyConnComp, stronglyConnCompR, SCC(..),
+	stronglyConnComp, stronglyConnCompR, SCC(..), flattenSCC, flattenSCCs,
 
 	Graph, Vertex, 
 	graphFromEdges, buildG, transposeG, reverseE, outdegree, indegree,
@@ -43,6 +43,7 @@ import ST
 import Maybe
 import Array
 import List
+import Outputable
 \end{code}
 
 
@@ -56,6 +57,18 @@ import List
 data SCC vertex = AcyclicSCC vertex
 	        | CyclicSCC  [vertex]
 
+flattenSCCs :: [SCC a] -> [a]
+flattenSCCs = concatMap flattenSCC
+
+flattenSCC (AcyclicSCC v) = [v]
+flattenSCC (CyclicSCC vs) = vs
+
+instance Outputable a => Outputable (SCC a) where
+   ppr (AcyclicSCC v) = text "NONREC" $$ (nest 3 (ppr v))
+   ppr (CyclicSCC vs) = text "REC" $$ (nest 3 (vcat (map ppr vs)))
+\end{code}
+
+\begin{code}
 stronglyConnComp
 	:: Ord key
 	=> [(node, key, [key])]		-- The graph; its ok for the