completing for release

examples/gfcc/compiler/Profile.hs

@@ -0,0 +1,90 @@
+module Profile (postParse) where
+
+import Trees
+import ErrM
+
+import Monad
+import List (nub)
+
+
+-- restoring parse trees for discontinuous constituents, bindings, etc. AR 25/1/2001
+-- revised 8/4/2002 for the new profile structure
+
+postParse :: CFTree -> Err Exp
+postParse tree = do
+  iterm <- tree2term tree
+  return $ term2trm  iterm
+
+-- an intermediate data structure
+data ITerm = ITerm (Atom, BindVs) [ITerm] | IMeta   deriving (Eq,Show)
+type BindVs = [[Ident]]
+
+-- the job is done in two passes: 
+-- (1) tree2term: restore constituent order from Profile 
+-- (2) term2trm:  restore Bindings from Binds
+
+tree2term :: CFTree -> Err ITerm
+tree2term (CFTree (cff@(CFFun (fun,pro)), trees)) = case fun of
+  AM -> return IMeta
+  _ -> do
+    args  <- mapM mkArg pro
+    binds <- mapM mkBinds pro
+    return $ ITerm (fun, binds) args
+ where
+   mkArg (_,arg) = case arg of
+     [x] -> do               -- one occurrence
+       trx <- trees !? x
+       tree2term trx
+     []  -> return IMeta     -- suppression
+     _   -> do               -- reduplication
+       trees' <- mapM (trees !?) arg
+       xs1    <- mapM tree2term trees' 
+       xs2    <- checkArity xs1
+       unif xs2
+
+   checkArity xs = if length (nub [length xx | ITerm _ xx <- xs']) > 1 
+                   then Bad "arity error" 
+                   else return xs'
+           where xs' = [t | t@(ITerm _ _) <- xs]
+   unif xs = case [t | t@(ITerm _ _) <- xs] of 
+    [] -> return $ IMeta
+    (ITerm fp@(f,_) xx : ts) -> do
+      let hs = [h | ITerm (h,_) _ <- ts, h /= f]
+      testErr (null hs)                 -- if fails, hs must be nonempty
+              ("unification expects " ++ prt f ++ " but found " ++ prt (head hs))
+      xx' <- mapM unifArg [0 .. length xx - 1]
+      return $ ITerm fp xx'
+    where
+      unifArg i = unif [zz !! i | ITerm _ zz <- xs]
+
+   mkBinds (xss,_) = mapM mkBind xss
+   mkBind xs = do
+     ts <- mapM (trees !?) xs
+     let vs = [x | CFTree (CFFun (AV x,_),[]) <- ts]
+     testErr (length ts == length vs) "non-variable in bound position"
+     case vs of
+       [x]  -> return x
+       []   -> return $ Ident "h_" ---- uBoundVar
+       y:ys -> do
+         testErr (all (==y) ys) ("fail to unify bindings of " ++ prt y)
+         return y
+
+term2trm :: ITerm -> Exp 
+term2trm IMeta = EAtom AM
+term2trm (ITerm (fun, binds) terms) =
+  let bterms = zip binds terms
+  in mkAppAtom fun [mkAbsR xs (term2trm t) |  (xs,t) <- bterms]
+
+ --- these are deprecated
+ where
+   mkAbsR c e = foldr EAbs e c
+   mkAppAtom a = mkApp (EAtom a)
+   mkApp = foldl EApp
+
+-- !! with the error monad
+(!?) :: [a] -> Int -> Err a
+xs !? i = foldr (const . return) (Bad "too few elements in list") $ drop i xs
+
+testErr :: Bool -> String -> Err ()
+testErr cond msg = if cond then return () else Bad msg
+