{- |

Module : $Header$

Copyright : (c) Christian Maeder and Uni Bremen 2002-2003

Licence : similar to LGPL, see HetCATS/LICENCE.txt or LIZENZ.txt

Maintainer : hets@tzi.de

Stability : provisional

Portability : non-portable (MonadState)

analyse alternatives of data types

-}

module HasCASL.DataAna where

import HasCASL.As

import Common.Id

import Common.Lib.State

import Common.Result

import HasCASL.Le

import HasCASL.TypeAna

import HasCASL.AsUtils

import HasCASL.Unify

import Data.Maybe

import Data.List

anaAlts :: [(Id, Type)] -> Type -> [Alternative] -> State Env [AltDefn]

anaAlts tys dt alts =

do ll <- mapM (anaAlt tys dt) alts

let l = concat ll

addDiags (checkUniqueness $ map ( \ (Construct i _ _ _) -> i) l)

return l

anaAlt :: [(Id, Type)] -> Type -> Alternative -> State Env [AltDefn]

anaAlt _ _ (Subtype ts ps) =

do mapM_ anaStarType ts

addDiags [Diag Warning "data subtype ignored" $ firstPos ts ps]

return []

anaAlt tys dt (Constructor i cs p _) =

do newCs <- mapM (anaComps i tys dt) $ zip cs $ map (:[]) [1..]

let mts = map fst newCs

if all isJust mts then

do let sels = concatMap snd newCs

con = Construct i (catMaybes mts) p sels

-- check for disjoint selectors

addDiags (checkUniqueness $ map ( \ (Select s _ _) -> s ) sels)

return [con]

else return []

getConstrType :: Type -> Partiality -> [Type] -> Type

getConstrType dt p = addPartiality p .

foldr ( \ c r -> FunType c FunArr r [] ) dt

addPartiality :: Partiality -> Type -> Type

addPartiality Total t = t

addPartiality Partial t = makePartial t

makePartial :: Type -> Type

makePartial t =

case t of

FunType t1 a t2 ps ->

case t2 of

FunType _ _ _ _ -> FunType t1 a (makePartial t2) ps

_ -> FunType t1 PFunArr t2 ps

_ -> LazyType t []

anaComps :: Id -> [(Id, Type)] -> Type -> ([Component], [Int])

-> State Env (Maybe Type, [Selector])

anaComps con tys rt (cs, i) =

do newCs <- mapM (anaComp con tys rt) $ zip cs $ map (:i) [1..]

let mts = map fst newCs

if all isJust mts then

return (Just $ ProductType (catMaybes mts) [],

concatMap snd newCs)

else return (Nothing, [])

anaComp :: Id -> [(Id, Type)] -> Type -> (Component, [Int])

-> State Env (Maybe Type, [Selector])

anaComp _ tys rt (Selector s p t _ _, _) =

do mt <- anaCompType tys rt t

case mt of

Just ct -> return (mt, [Select s ct p])

_ -> return (Nothing, [])

anaComp con tys rt (NoSelector t, i) =

do mt <- anaCompType tys rt t

case mt of

Just ct -> return (mt, [Select (simpleIdToId $ mkSimpleId

("%(" ++ showPretty rt "." ++

showId con ".sel_" ++ show i ++ ")%"))

ct Partial])

_ -> return (Nothing, [])

getSelType :: Type -> Partiality -> Type -> Type

getSelType dt p rt = addPartiality p $ FunType dt FunArr rt []

anaCompType :: [(Id, Type)] -> Type -> Type -> State Env (Maybe Type)

anaCompType tys dt t = do

mt <- anaStarType t

case mt of

Nothing -> return Nothing

Just ct -> do mt2 <- unboundTypevars (varsOf dt) ct

case mt2 of

Nothing -> return Nothing

Just ct2 -> do

ms <- mapM

(checkMonomorphRecursion ct2) tys

return $ if and ms then Just ct2

else Nothing

checkMonomorphRecursion :: Type -> (Id, Type) -> State Env Bool

checkMonomorphRecursion t (i, rt) =

if i `occursIn` t then

if t == rt then return True

else do addDiags [Diag Error ("illegal polymorphic recursion"

++ expected rt t) $ getMyPos t]

return False

else return True

unboundTypevars :: [TypeArg] -> Type -> State Env (Maybe Type)

unboundTypevars args ct = do

let restVars = varsOf ct \\ args

if null restVars then do return $ Just ct

else do addDiags [Diag Error ("unbound type variable(s)\n\t"

++ showSepList ("," ++) showPretty

restVars "") $ posOf restVars]

return Nothing