{- |

Module : $Header$

Description : analysis of data type declarations

Copyright : (c) Christian Maeder and Uni Bremen 2002-2005

License : GPLv2 or higher

Maintainer : Christian.Maeder@dfki.de

Stability : provisional

Portability : portable

analyse alternatives of data types

-}

module HasCASL.DataAna

( DataPat(..)

, toDataPat

, getConstrScheme

, getSelScheme

, anaAlts

, makeDataSelEqs

, inductionScheme

, mkVarDecl

) where

import Common.AS_Annotation

import Common.Id

import Common.Result

import HasCASL.As

import HasCASL.AsUtils

import HasCASL.Builtin

import HasCASL.Le

import HasCASL.TypeAna

import HasCASL.Unify

import Control.Monad

import Data.Maybe (mapMaybe)

import qualified Data.Map as Map

import qualified Data.Set as Set

{- | description of polymorphic data types. The top-level identifier is

already renamed according the IdMap. -}

data DataPat = DataPat IdMap Id [TypeArg] RawKind Type

mkVarDecl :: Id -> Type -> VarDecl

mkVarDecl i t = VarDecl i t Other nullRange

mkSelId :: Range -> String -> Int -> Int -> Id

mkSelId p str n m = mkId

[Token (str ++ "_" ++ (if n < 1 then "" else show n ++ "_") ++ show m) p]

mkSelVar :: Int -> Int -> Type -> VarDecl

mkSelVar n m ty = mkVarDecl (mkSelId (getRange ty) "x" n m) ty

genTuple :: Int -> Int -> [Selector] -> [(Selector, VarDecl)]

genTuple _ _ [] = []

genTuple n m (s@(Select _ ty _) : sels) =

(s, mkSelVar n m ty) : genTuple n (m + 1) sels

genSelVars :: Int -> [[Selector]] -> [[(Selector, VarDecl)]]

genSelVars n sels = case sels of

[ts] -> [genTuple 0 1 ts]

_ -> if all isSingle sels

then map (: []) $ genTuple 0 1 $ map head sels

else genSelVarsAux n sels

genSelVarsAux :: Int -> [[Selector]] -> [[(Selector, VarDecl)]]

genSelVarsAux _ [] = []

genSelVarsAux n (ts : sels) =

genTuple n 1 ts : genSelVarsAux (n + 1) sels

makeSelTupleEqs :: DataPat -> Term -> [(Selector, VarDecl)] -> [Named Term]

makeSelTupleEqs dt ct = concatMap (\ (Select mi ty p, v) -> case mi of

Just i -> let

sc = getSelScheme dt p ty

eq = mkEqTerm eqId ty nullRange

(mkApplTerm (mkOpTerm i sc) [ct]) $ QualVar v

in [makeNamed ("ga_select_" ++ show i) eq]

_ -> [])

makeSelEqs :: DataPat -> Term -> [[(Selector, VarDecl)]] -> [Named Term]

makeSelEqs dt = concatMap . makeSelTupleEqs dt

makeAltSelEqs :: DataPat -> AltDefn -> [Named Term]

makeAltSelEqs dt@(DataPat _ _ iargs _ _) (Construct mc ts p sels) =

case mc of

Nothing -> []

Just c -> let

selvars = genSelVars 1 sels

vars = map (map snd) selvars

ars = mkSelArgs vars

ct = mkApplTerm (mkOpTerm c $ getConstrScheme dt p ts) ars

in map (mapNamed (mkForall (map GenTypeVarDecl iargs

++ map GenVarDecl (concat vars)))) $ makeSelEqs dt ct selvars

mkSelArgs :: [[VarDecl]] -> [Term]

mkSelArgs = map (\ vs -> mkTupleTerm (map QualVar vs) nullRange)

getConstrScheme :: DataPat -> Partiality -> [Type] -> TypeScheme

getConstrScheme (DataPat dm _ args _ rt) p ts =

let realTs = map (mapType dm) ts

in TypeScheme args (getFunType rt p realTs) nullRange

getSelScheme :: DataPat -> Partiality -> Type -> TypeScheme

getSelScheme (DataPat dm _ args _ rt) p t =

let realT = mapType dm t

in TypeScheme args (getSelType rt p realT) nullRange

-- | remove variances from generalized type arguments

toDataPat :: DataEntry -> DataPat

toDataPat (DataEntry im i _ args rk _) = let j = Map.findWithDefault i i im in

DataPat im j (map nonVarTypeArg args) rk $ patToType j args rk

-- | create selector equations for a data type

makeDataSelEqs :: DataPat -> [AltDefn] -> [Named Sentence]

makeDataSelEqs dp = map (mapNamed Formula) . concatMap (makeAltSelEqs dp)

-- | analyse the alternatives of a data type

anaAlts :: GenKind -> [DataPat] -> DataPat -> [Alternative] -> Env

-> Result [AltDefn]

anaAlts genKind tys dt alts te =

do l <- mapM (anaAlt genKind tys dt te) alts

Result (checkUniqueness $ mapMaybe ( \ (Construct i _ _ _) -> i) l)

$ Just ()

return l

anaAlt :: GenKind -> [DataPat] -> DataPat -> Env -> Alternative

-> Result AltDefn

anaAlt _ _ _ te (Subtype ts _) =

do l <- mapM ( \ t -> anaStarTypeM t te) ts

return $ Construct Nothing (Set.toList $ Set.fromList $ map snd l)

Partial []

anaAlt genKind tys dt te (Constructor i cs p _) =

do newCs <- mapM (anaComps genKind tys dt te) cs

let sels = map snd newCs

Result (checkUniqueness . mapMaybe ( \ (Select s _ _) -> s )

$ concat sels) $ Just ()

return $ Construct (Just i) (map fst newCs) p sels

anaComps :: GenKind -> [DataPat] -> DataPat -> Env -> [Component]

-> Result (Type, [Selector])

anaComps genKind tys rt te cs =

do newCs <- mapM (anaComp genKind tys rt te) cs

return (mkProductType $ map fst newCs, map snd newCs)

isPartialSelector :: Type -> Bool

isPartialSelector ty = case ty of

TypeAppl (TypeName i _ _) _ -> i == lazyTypeId

_ -> False

anaComp :: GenKind -> [DataPat] -> DataPat -> Env -> Component

-> Result (Type, Selector)

anaComp genKind tys rt te (Selector s _ t _ _) =

do ct <- anaCompType genKind tys rt t te

let (p, nct) = case getTypeAppl ct of

(TypeName i _ _, [lt]) | i == lazyTypeId

&& isPartialSelector t -> (Partial, lt)

_ -> (Total, ct)

return (nct, Select (Just s) nct p)

anaComp genKind tys rt te (NoSelector t) =

do ct <- anaCompType genKind tys rt t te

return (ct, Select Nothing ct Partial)

anaCompType :: GenKind -> [DataPat] -> DataPat -> Type -> Env -> Result Type

anaCompType genKind tys (DataPat _ _ tArgs _ _) t te = do

(_, ct) <- anaStarTypeM t te

let ds = unboundTypevars True tArgs ct

unless (null ds) $ Result ds Nothing

mapM_ (checkMonomorphRecursion ct te) tys

mapM_ (rejectNegativeOccurrence genKind ct te) tys

return $ generalize tArgs ct

checkMonomorphRecursion :: Type -> Env -> DataPat -> Result ()

checkMonomorphRecursion t te (DataPat _ i _ _ rt) =

case filter (\ ty -> not (lesserType te ty rt || lesserType te rt ty))

$ findSubTypes (relatedTypeIds (typeMap te) i) i t of

[] -> return ()

ty : _ -> Result [Diag Error ("illegal polymorphic recursion"

++ expected rt ty) $ getRange ty] Nothing

findSubTypes :: (Id -> Bool) -> Id -> Type -> [Type]

findSubTypes chk i t = case getTypeAppl t of

(TypeName j _ _, args) -> if chk j then [t]

else concatMap (findSubTypes chk i) args

(topTy, args) -> concatMap (findSubTypes chk i) $ topTy : args

rejectNegativeOccurrence :: GenKind -> Type -> Env -> DataPat -> Result ()

rejectNegativeOccurrence genKind t te (DataPat _ i _ _ _) =

case findNegativeOccurrence te i t of

[] -> return ()

ty : _ -> Result [mkDiag (case genKind of

Free -> Error

_ -> Hint) "negative datatype occurrence of" ty] $ Just ()

findNegativeOccurrence :: Env -> Id -> Type -> [Type]

findNegativeOccurrence te i t = let tm = typeMap te in case getTypeAppl t of

(TypeName j _ _, _) | relatedTypeIds tm i j ->

[] -- positive occurrence

(topTy, [larg, rarg]) | lesserType te topTy (toFunType PFunArr) ->

findSubTypes (== i) i larg ++ findNegativeOccurrence te i rarg

(_, args) -> concatMap (findNegativeOccurrence te i) args

relatedTypeIds :: TypeMap -> Id -> Id -> Bool

relatedTypeIds tm i1 i2 =

not $ Set.null $ Set.intersection (allRelIds tm i1) $ allRelIds tm i2

allRelIds :: TypeMap -> Id -> Set.Set Id

allRelIds tm i = Set.union (superIds tm i) $ subIds tm i

subIds :: TypeMap -> Id -> Set.Set Id

subIds tm i = foldr ( \ j s ->

if Set.member i $ superIds tm j then

Set.insert j s else s) Set.empty $ Map.keys tm

mkPredVar :: DataPat -> VarDecl

mkPredVar (DataPat _ i _ _ rt) = let ps = posOfId i in

mkVarDecl (if isSimpleId i then mkId [mkSimpleId $ "p_" ++ show i]

else Id [mkSimpleId "p"] [i] ps) (predType ps rt)

mkPredAppl :: DataPat -> Term -> Term

mkPredAppl dp t = mkApplTerm (QualVar $ mkPredVar dp) [t]

mkPredToVarAppl :: DataPat -> VarDecl -> Term

mkPredToVarAppl dp = mkPredAppl dp . QualVar

mkConclusion :: DataPat -> Term

mkConclusion dp@(DataPat _ _ _ _ ty) =

let v = mkVarDecl (mkId [mkSimpleId "x"]) ty

in mkForall [GenVarDecl v] $ mkPredToVarAppl dp v

mkPremise :: Map.Map Type DataPat -> DataPat -> AltDefn -> [Term]

mkPremise m dp (Construct mc ts p sels) =

case mc of

Nothing -> []

Just c -> let

vars = map (map snd) $ genSelVars 1 sels

findHypo vd@(VarDecl _ ty _ _) =

fmap (flip mkPredToVarAppl vd) $ Map.lookup ty m

flatVars = concat vars

indHypos = mapMaybe findHypo flatVars

indConcl = mkPredAppl dp

$ mkApplTerm (mkOpTerm c $ getConstrScheme dp p ts)

$ mkSelArgs vars

in [mkForall (map GenVarDecl flatVars) $

if null indHypos then indConcl else

mkLogTerm implId nullRange (mkConjunct indHypos) indConcl]

mkConjunct :: [Term] -> Term

mkConjunct ts = if null ts then error "HasCASL.DataAna.mkConjunct" else

toBinJunctor andId ts nullRange

mkPremises :: Map.Map Type DataPat -> DataEntry -> [Term]

mkPremises m de@(DataEntry _ _ _ _ _ alts) =

concatMap (mkPremise m $ toDataPat de) $ Set.toList alts

joinTypeArgs :: [DataPat] -> Map.Map Id TypeArg

joinTypeArgs = foldr (\ (DataPat _ _ iargs _ _) m ->

foldr (\ ta -> Map.insert (getTypeVar ta) ta) m iargs) Map.empty

inductionScheme :: [DataEntry] -> Term

inductionScheme des =

let dps = map toDataPat des

m = Map.fromList $ map (\ dp@(DataPat _ _ _ _ ty) -> (ty, dp)) dps

in mkForall (map GenTypeVarDecl (Map.elems $ joinTypeArgs dps)

++ map (GenVarDecl . mkPredVar) dps)

$ mkLogTerm implId nullRange

(mkConjunct $ concatMap (mkPremises m) des)

$ mkConjunct $ map mkConclusion dps