Rename a DFA's and NFA's states

src/Rextra/Util.hs

@@ -1,5 +1,15 @@
+{-# LANGUAGE TupleSections #-}
+
 module Rextra.Util
   ( connectedElements
+  -- * Renaming
+  , Rename
+  , doRename
+  , getName
+  , renameSet
+  , renameMap
+  , renameKeys
+  , renameValues
   ) where
 
 import           Control.Monad
@@ -17,3 +27,30 @@ explore trans node = do
 connectedElements :: (Ord n) => (n -> Set.Set n) -> Set.Set n -> Set.Set n
 connectedElements trans startingNodes =
   flip execState Set.empty . mapM (explore trans) $ Set.toList startingNodes
+
+type Rename n = State (Int, Map.Map n Int)
+
+doRename :: Rename n a -> a
+doRename rename = evalState rename (0, Map.empty)
+
+getName :: (Ord n) => n -> Rename n Int
+getName thing = do
+  (i, names) <- get
+  case names Map.!? thing of
+    Just name -> pure name
+    Nothing   -> i <$ put (i + 1, Map.insert thing i names)
+
+renameSet :: (Ord v2) => (v1 -> Rename n v2) -> Set.Set v1 -> Rename n (Set.Set v2)
+renameSet renameFunc s = Set.fromList <$> (mapM renameFunc $ Set.toList s)
+
+renameMap :: (Ord k2)
+          => ((k1, v1) -> Rename n (k2, v2))
+          -> Map.Map k1 v1
+          -> Rename n (Map.Map k2 v2)
+renameMap f m = Map.fromList <$> (mapM f $ Map.assocs m)
+
+renameKeys :: (Ord k2) => (k1 -> Rename n k2) -> Map.Map k1 v -> Rename n (Map.Map k2 v)
+renameKeys f = renameMap (\(k, v) -> (,v) <$> f k)
+
+renameValues :: (Ord k) => (v1 -> Rename n v2) -> Map.Map k v1 -> Rename n (Map.Map k v2)
+renameValues f = renameMap (\(k, v) -> (k,) <$> f v)