\begin{code}
-# include "HsVersions.h"
-
module Digraph(
-- At present the only one with a "nice" external interface
stronglyConnComp, stronglyConnCompR, SCC(..),
- SYN_IE(Graph), SYN_IE(Vertex),
+ Graph, Vertex,
graphFromEdges, buildG, transposeG, reverseE, outdegree, indegree,
- Tree(..), SYN_IE(Forest),
+ Tree(..), Forest,
showTree, showForest,
dfs, dff,
) where
+# include "HsVersions.h"
+
------------------------------------------------------------------------------
-- A version of the graph algorithms described in:
--
-- Also included is some additional code for printing tree structures ...
------------------------------------------------------------------------------
-#ifdef REALLY_HASKELL_1_3
#define ARR_ELT (COMMA)
-import Array
-import List
-import ST
-import ArrBase
-import Maybe
-
-#else
-
-#define ARR_ELT (:=)
-#define runST _runST
-#define MutableArray _MutableArray
-#define Show Text
+import Util ( sortLt )
-import PreludeGlaST
-import Maybes ( mapMaybe )
-
-#endif
+-- GHC extensions
+import ST
+import MutableArray
-import Util ( Ord3(..),
- sortLt
- )
+-- std interfaces
+import Maybe
+import Array
+import List
\end{code}
| CyclicSCC [vertex]
stronglyConnComp
- :: Ord3 key
+ :: Ord key
=> [(node, key, [key])] -- The graph; its ok for the
-- out-list to contain keys which arent
-- a vertex key, they are ignored
-- The "R" interface is used when you expect to apply SCC to
-- the (some of) the result of SCC, so you dont want to lose the dependency info
stronglyConnCompR
- :: Ord3 key
+ :: Ord key
=> [(node, key, [key])] -- The graph; its ok for the
-- out-list to contain keys which arent
-- a vertex key, they are ignored
edges g = [ (v, w) | v <- vertices g, w <- g!v ]
mapT :: (Vertex -> a -> b) -> Table a -> Table b
-mapT f t = array (bounds t) [ ARR_ELT v (f v (t!v)) | v <- indices t ]
+mapT f t = array (bounds t) [ (,) v (f v (t!v)) | v <- indices t ]
buildG :: Bounds -> [Edge] -> Graph
#ifdef REALLY_HASKELL_1_3
buildG bounds edges = accumArray (flip (:)) [] bounds edges
#else
-buildG bounds edges = accumArray (flip (:)) [] bounds [ARR_ELT k v | (k,v) <- edges]
+buildG bounds edges = accumArray (flip (:)) [] bounds [(,) k v | (k,v) <- edges]
#endif
transposeG :: Graph -> Graph
\begin{code}
graphFromEdges
- :: Ord3 key
+ :: Ord key
=> [(node, key, [key])]
-> (Graph, Vertex -> (node, key, [key]))
graphFromEdges edges
max_v = length edges - 1
bounds = (0,max_v) :: (Vertex, Vertex)
sorted_edges = sortLt lt edges
- edges1 = zipWith ARR_ELT [0..] sorted_edges
+ edges1 = zipWith (,) [0..] sorted_edges
- graph = array bounds [ARR_ELT v (mapMaybe key_vertex ks) | ARR_ELT v (_, _, ks) <- edges1]
- key_map = array bounds [ARR_ELT v k | ARR_ELT v (_, k, _ ) <- edges1]
+ 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 `cmp` k2 of { LT_ -> True; other -> False }
+ (_,k1,_) `lt` (_,k2,_) = case k1 `compare` k2 of { LT -> True; other -> False }
-- key_vertex :: key -> Maybe Vertex
-- returns Nothing for non-interesting vertices
where
find a b | a > b
= Nothing
- find a b = case cmp k (key_map ! mid) of
- LT_ -> find a (mid-1)
- EQ_ -> Just mid
- GT_ -> find (mid+1) b
+ find a b = case compare k (key_map ! mid) of
+ LT -> find a (mid-1)
+ EQ -> Just mid
+ GT -> find (mid+1) b
where
mid = (a + b) `div` 2
\end{code}
generate g v = Node v (map (generate g) (g!v))
prune :: Bounds -> Forest Vertex -> Forest Vertex
-prune bnds ts = runST (mkEmpty bnds `thenST` \m ->
+prune bnds ts = runST (mkEmpty bnds >>= \m ->
chop m ts)
chop :: Set s -> Forest Vertex -> ST s (Forest Vertex)
-chop m [] = returnST []
+chop m [] = return []
chop m (Node v ts : us)
- = contains m v `thenStrictlyST` \visited ->
+ = contains m v >>= \visited ->
if visited then
chop m us
else
- include m v `thenStrictlyST` \_ ->
- chop m ts `thenStrictlyST` \as ->
- chop m us `thenStrictlyST` \bs ->
- returnST (Node v as : bs)
+ include m v >>= \_ ->
+ chop m ts >>= \as ->
+ chop m us >>= \bs ->
+ return (Node v as : bs)
\end{code}
preOrd = preorderF . dff
tabulate :: Bounds -> [Vertex] -> Table Int
-tabulate bnds vs = array bnds (zipWith ARR_ELT vs [1..])
+tabulate bnds vs = array bnds (zipWith (,) vs [1..])
preArr :: Bounds -> Forest Vertex -> Table Int
preArr bnds = tabulate bnds . preorderF