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|
----------------------------------------------------------------------
-- |
-- Module : AppPredefined
-- Maintainer : AR
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/10/06 14:21:34 $
-- > CVS $Author: aarne $
-- > CVS $Revision: 1.13 $
--
-- Predefined function type signatures and definitions.
-----------------------------------------------------------------------------
module GF.Grammar.AppPredefined (isInPredefined, typPredefined, appPredefined
) where
import GF.Infra.Ident
import GF.Data.Operations
import GF.Grammar.Predef
import GF.Grammar.Grammar
import GF.Grammar.Macros
import GF.Grammar.PrGrammar (prt,prt_,prtBad)
import qualified Data.ByteString.Char8 as BS
-- predefined function type signatures and definitions. AR 12/3/2003.
isInPredefined :: Ident -> Bool
isInPredefined = err (const True) (const False) . typPredefined
typPredefined :: Ident -> Err Type
typPredefined f
| f == cInt = return typePType
| f == cFloat = return typePType
| f == cErrorType = return typeType
| f == cInts = return $ mkFunType [typeInt] typePType
| f == cPBool = return typePType
| f == cError = return $ mkFunType [typeStr] typeError -- non-can. of empty set
| f == cPFalse = return $ typePBool
| f == cPTrue = return $ typePBool
| f == cDp = return $ mkFunType [typeInt,typeTok] typeTok
| f == cDrop = return $ mkFunType [typeInt,typeTok] typeTok
| f == cEqInt = return $ mkFunType [typeInt,typeInt] typePBool
| f == cLessInt = return $ mkFunType [typeInt,typeInt] typePBool
| f == cEqStr = return $ mkFunType [typeTok,typeTok] typePBool
| f == cLength = return $ mkFunType [typeTok] typeInt
| f == cOccur = return $ mkFunType [typeTok,typeTok] typePBool
| f == cOccurs = return $ mkFunType [typeTok,typeTok] typePBool
| f == cPlus = return $ mkFunType [typeInt,typeInt] (typeInt)
---- "read" -> (P : Type) -> Tok -> P
| f == cShow = return $ mkProd -- (P : PType) -> P -> Tok
([(varP,typePType),(identW,Vr varP)],typeStr,[])
| f == cToStr = return $ mkProd -- (L : Type) -> L -> Str
([(varL,typeType),(identW,Vr varL)],typeStr,[])
| f == cMapStr = return $ mkProd -- (L : Type) -> (Str -> Str) -> L -> L
([(varL,typeType),(identW,mkFunType [typeStr] typeStr),(identW,Vr varL)],Vr varL,[])
| f == cTake = return $ mkFunType [typeInt,typeTok] typeTok
| f == cTk = return $ mkFunType [typeInt,typeTok] typeTok
| otherwise = prtBad "unknown in Predef:" f
varL :: Ident
varL = identC (BS.pack "L")
varP :: Ident
varP = identC (BS.pack "P")
appPredefined :: Term -> Err (Term,Bool)
appPredefined t = case t of
App f x0 -> do
(x,_) <- appPredefined x0
case f of
-- one-place functions
Q mod f | mod == cPredef ->
case x of
(K s) | f == cLength -> retb $ EInt $ toInteger $ length s
_ -> retb t
-- two-place functions
App (Q mod f) z0 | mod == cPredef -> do
(z,_) <- appPredefined z0
case (norm z, norm x) of
(EInt i, K s) | f == cDrop -> retb $ K (drop (fi i) s)
(EInt i, K s) | f == cTake -> retb $ K (take (fi i) s)
(EInt i, K s) | f == cTk -> retb $ K (take (max 0 (length s - fi i)) s)
(EInt i, K s) | f == cDp -> retb $ K (drop (max 0 (length s - fi i)) s)
(K s, K t) | f == cEqStr -> retb $ if s == t then predefTrue else predefFalse
(K s, K t) | f == cOccur -> retb $ if substring s t then predefTrue else predefFalse
(K s, K t) | f == cOccurs -> retb $ if any (flip elem t) s then predefTrue else predefFalse
(EInt i, EInt j) | f == cEqInt -> retb $ if i==j then predefTrue else predefFalse
(EInt i, EInt j) | f == cLessInt -> retb $ if i<j then predefTrue else predefFalse
(EInt i, EInt j) | f == cPlus -> retb $ EInt $ i+j
(_, t) | f == cShow -> retb $ foldr C Empty $ map K $ words $ prt t
(_, K s) | f == cRead -> retb $ Cn (identC (BS.pack s)) --- because of K, only works for atomic tags
(_, t) | f == cToStr -> trm2str t >>= retb
_ -> retb t ---- prtBad "cannot compute predefined" t
-- three-place functions
App (App (Q mod f) z0) y0 | mod == cPredef -> do
(y,_) <- appPredefined y0
(z,_) <- appPredefined z0
case (z, y, x) of
(ty,op,t) | f == cMapStr -> retf $ mapStr ty op t
_ -> retb t ---- prtBad "cannot compute predefined" t
_ -> retb t ---- prtBad "cannot compute predefined" t
_ -> retb t
---- should really check the absence of arg variables
where
retb t = return (retc t,True) -- no further computing needed
retf t = return (retc t,False) -- must be computed further
retc t = case t of
K [] -> t
K s -> foldr1 C (map K (words s))
_ -> t
norm t = case t of
Empty -> K []
C u v -> case (norm u,norm v) of
(K x,K y) -> K (x +++ y)
_ -> t
_ -> t
fi = fromInteger
-- read makes variables into constants
predefTrue = Q cPredef cPTrue
predefFalse = Q cPredef cPFalse
substring :: String -> String -> Bool
substring s t = case (s,t) of
(c:cs, d:ds) -> (c == d && substring cs ds) || substring s ds
([],_) -> True
_ -> False
trm2str :: Term -> Err Term
trm2str t = case t of
R ((_,(_,s)):_) -> trm2str s
T _ ((_,s):_) -> trm2str s
TSh _ ((_,s):_) -> trm2str s
V _ (s:_) -> trm2str s
C _ _ -> return $ t
K _ -> return $ t
S c _ -> trm2str c
Empty -> return $ t
_ -> prtBad "cannot get Str from term" t
-- simultaneous recursion on type and term: type arg is essential!
-- But simplify the task by assuming records are type-annotated
-- (this has been done in type checking)
mapStr :: Type -> Term -> Term -> Term
mapStr ty f t = case (ty,t) of
_ | elem ty [typeStr,typeTok] -> App f t
(_, R ts) -> R [(l,mapField v) | (l,v) <- ts]
(Table a b,T ti cs) -> T ti [(p,mapStr b f v) | (p,v) <- cs]
_ -> t
where
mapField (mty,te) = case mty of
Just ty -> (mty,mapStr ty f te)
_ -> (mty,te)
|
