[project @ 2005-04-28 15:28:05 by simonmar]

[ghc-hetmet.git] / ghc / compiler / utils / Digraph.lhs

diff --git a/ghc/compiler/utils/Digraph.lhs b/ghc/compiler/utils/Digraph.lhs
index cd0e17d..c49087c 100644 (file)
--- a/ghc/compiler/utils/Digraph.lhs
+++ b/ghc/compiler/utils/Digraph.lhs
@@ -5,7 +5,8 @@ module Digraph(
        stronglyConnComp, stronglyConnCompR, SCC(..), flattenSCC, flattenSCCs,
 
        Graph, Vertex, 
-       graphFromEdges, buildG, transposeG, reverseE, outdegree, indegree,
+       graphFromEdges, graphFromEdges', 
+       buildG, transposeG, reverseE, outdegree, indegree,
 
        Tree(..), Forest,
        showTree, showForest,
@@ -32,7 +33,7 @@ module Digraph(
 ------------------------------------------------------------------------------
 
 
-import Util    ( sortLt )
+import Util    ( sortLe )
 
 -- Extensions
 import MONAD_ST
@@ -100,8 +101,8 @@ stronglyConnCompR [] = []  -- added to avoid creating empty array in graphFromEd
 stronglyConnCompR edges
   = map decode forest
   where
-    (graph, vertex_fn) = graphFromEdges edges
-    forest            = scc graph
+    (graph, vertex_fn) = _scc_ "graphFromEdges" graphFromEdges edges
+    forest            = _scc_ "Digraph.scc" scc graph
     decode (Node v []) | mentions_itself v = CyclicSCC [vertex_fn v]
                       | otherwise         = AcyclicSCC (vertex_fn v)
     decode other = CyclicSCC (dec other [])
@@ -154,23 +155,32 @@ indegree  = outdegree . transposeG
 
 
 \begin{code}
-graphFromEdges
+graphFromEdges 
        :: Ord key
        => [(node, key, [key])]
        -> (Graph, Vertex -> (node, key, [key]))
-graphFromEdges edges
-  = (graph, \v -> vertex_map ! v)
+graphFromEdges edges = 
+  case graphFromEdges' edges of (graph, vertex_fn, _) -> (graph, vertex_fn) 
+
+graphFromEdges'
+       :: Ord key
+       => [(node, key, [key])]
+       -> (Graph, Vertex -> (node, key, [key]), key -> Maybe Vertex)
+graphFromEdges' edges
+  = (graph, \v -> vertex_map ! v, key_vertex)
   where
     max_v                  = length edges - 1
     bounds          = (0,max_v) :: (Vertex, Vertex)
-    sorted_edges    = sortLt lt edges
+    sorted_edges    = let
+                        (_,k1,_) `le` (_,k2,_) = case k1 `compare` k2 of { GT -> False; other -> True }
+                     in
+                       sortLe le edges
     edges1         = zipWith (,) [0..] sorted_edges
 
     graph          = array bounds [(,) v (mapMaybe key_vertex ks) | (,) v (_,    _, ks) <- edges1]
     key_map        = array bounds [(,) v k                        | (,) v (_,    k, _ ) <- edges1]
     vertex_map     = array bounds edges1
 
-    (_,k1,_) `lt` (_,k2,_) = case k1 `compare` k2 of { LT -> True; other -> False }
 
     -- key_vertex :: key -> Maybe Vertex
     --         returns Nothing for non-interesting vertices