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|
----------------------------------------------------------------------
-- |
-- Module : Ident
-- Maintainer : AR
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/11/15 11:43:33 $
-- > CVS $Author: aarne $
-- > CVS $Revision: 1.8 $
--
-- (Description of the module)
-----------------------------------------------------------------------------
module GF.Infra.Ident (-- * Identifiers
Ident(..), prIdent,
identC, identV, identA, identAV, identW,
argIdent, strVar, wildIdent, isWildIdent,
newIdent, mkIdent, varIndex,
-- * refreshing identifiers
IdState, initIdStateN, initIdState,
lookVar, refVar, refVarPlus
) where
import GF.Data.Operations
-- import Monad
-- | the constructors labelled /INTERNAL/ are
-- internal representation never returned by the parser
data Ident =
IC String -- ^ raw identifier after parsing, resolved in Rename
| IW -- ^ wildcard
--
-- below this constructor: internal representation never returned by the parser
| IV (Int,String) -- ^ /INTERNAL/ variable
| IA (String,Int) -- ^ /INTERNAL/ argument of cat at position
| IAV (String,Int,Int) -- ^ /INTERNAL/ argument of cat with bindings at position
--
deriving (Eq, Ord, Show, Read)
prIdent :: Ident -> String
prIdent i = case i of
IC s -> s
IV (n,s) -> s ++ "_" ++ show n
IA (s,j) -> s ++ "_" ++ show j
IAV (s,b,j) -> s ++ "_" ++ show b ++ "_" ++ show j
IW -> "_"
identC :: String -> Ident
identV :: (Int, String) -> Ident
identA :: (String, Int) -> Ident
identAV:: (String, Int, Int) -> Ident
identW :: Ident
(identC, identV, identA, identAV, identW) =
(IC, IV, IA, IAV, IW)
-- normal identifier
-- ident s = IC s
-- | to mark argument variables
argIdent :: Int -> Ident -> Int -> Ident
argIdent 0 (IC c) i = identA (c,i)
argIdent b (IC c) i = identAV (c,b,i)
-- | used in lin defaults
strVar :: Ident
strVar = identA ("str",0)
-- | wild card
wildIdent :: Ident
wildIdent = identW
isWildIdent :: Ident -> Bool
isWildIdent x = case x of
IW -> True
IC "_" -> True
_ -> False
newIdent :: Ident
newIdent = identC "#h"
mkIdent :: String -> Int -> Ident
mkIdent s i = identV (i,s)
varIndex :: Ident -> Int
varIndex (IV (n,_)) = n
varIndex _ = -1 --- other than IV should not count
-- refreshing identifiers
type IdState = ([(Ident,Ident)],Int)
initIdStateN :: Int -> IdState
initIdStateN i = ([],i)
initIdState :: IdState
initIdState = initIdStateN 0
lookVar :: Ident -> STM IdState Ident
lookVar a@(IA _) = return a
lookVar x = do
(sys,_) <- readSTM
stm (\s -> maybe (Bad ("cannot find" +++ show x +++ prParenth (show sys)))
return $
lookup x sys >>= (\y -> return (y,s)))
refVar :: Ident -> STM IdState Ident
----refVar IW = return IW --- no update of wildcard
refVar x = do
(_,m) <- readSTM
let x' = IV (m, prIdent x)
updateSTM (\ (sys,mx) -> ((x, x'):sys, mx + 1))
return x'
refVarPlus :: Ident -> STM IdState Ident
----refVarPlus IW = refVar (identC "h")
refVarPlus x = refVar x
{-
------------------------------
-- to test
refreshExp :: Exp -> Err Exp
refreshExp e = err Bad (return . fst) (appSTM (refresh e) initState)
refresh :: Exp -> STM State Exp
refresh e = case e of
Atom x -> lookVar x >>= return . Atom
App f a -> liftM2 App (refresh f) (refresh a)
Abs x b -> liftM2 Abs (refVar x) (refresh b)
Fun xs a b -> do
a' <- refresh a
xs' <- mapM refVar xs
b' <- refresh b
return $ Fun xs' a' b'
data Exp =
Atom Ident
| App Exp Exp
| Abs Ident Exp
| Fun [Ident] Exp Exp
deriving Show
exp1 = Abs (IC "y") (Atom (IC "y"))
exp2 = Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "y")))
exp3 = Abs (IC "y") (Abs (IC "z") (App (Atom (IC "y")) (Atom (IC "z"))))
exp4 = Abs (IC "y") (Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "z"))))
exp5 = Abs (IC "y") (Abs (IC "y") (App (Atom (IC "y")) (Atom (IC "y"))))
exp6 = Abs (IC "y") (Fun [IC "x", IC "y"] (Atom (IC "y")) (Atom (IC "y")))
exp7 = Abs (IL "8") (Atom (IC "y"))
-}
|
