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|
----------------------------------------------------------------------
-- |
-- Maintainer : PL
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/04/16 05:40:49 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.4 $
--
-- Simplistic GFC format
-----------------------------------------------------------------------------
module GF.Formalism.SimpleGFC where
import Monad (liftM)
import qualified AbsGFC
import qualified Ident
import GF.Formalism.GCFG
import GF.Infra.Print
----------------------------------------------------------------------
-- * basic (leaf) types
type Constr = AbsGFC.CIdent
type Var = Ident.Ident
type Label = AbsGFC.Label
anyVar :: Var
anyVar = Ident.wildIdent
----------------------------------------------------------------------
-- * simple GFC
type SimpleGrammar c n t = Grammar (Decl c) n (LinType c t) (Maybe (Term c t))
type SimpleRule c n t = Rule (Decl c) n (LinType c t) (Maybe (Term c t))
-- ** dependent type declarations
-- | 'Decl x c ts' == x is of type (c applied to ts)
data Decl c = Decl Var c [TTerm]
deriving (Eq, Ord, Show)
data TTerm = Constr :@ [TTerm]
| TVar Var
deriving (Eq, Ord, Show)
decl2cat :: Decl c -> c
decl2cat (Decl _ cat _) = cat
varsInTTerm :: TTerm -> [Var]
varsInTTerm tterm = vars tterm []
where vars (TVar x) = (x:)
vars (_ :@ ts) = foldr (.) id $ map vars ts
tterm2term :: TTerm -> Term c t
tterm2term (con :@ terms) = con :^ map tterm2term terms
tterm2term (TVar x) = Var x
term2tterm :: Term c t -> TTerm
term2tterm (con :^ terms) = con :@ map term2tterm terms
term2tterm (Var x) = TVar x
term2tterm term = error $ "term2tterm: illegal term"
-- ** linearization types and terms
data LinType c t = RecT [(Label, LinType c t)]
| TblT (LinType c t) (LinType c t)
| ConT Constr [Term c t]
| StrT
deriving (Eq, Ord, Show)
isBaseType :: LinType c t -> Bool
isBaseType (ConT _ _) = True
isBaseType (StrT) = True
isBaseType _ = False
data Term c t
= Arg Int c (Path c t) -- ^ argument variable, the 'Path' is a path
-- pointing into the term
| Constr :^ [Term c t] -- ^ constructor
| Rec [(Label, Term c t)] -- ^ record
| Term c t :. Label -- ^ record projection
| Tbl [(Term c t, Term c t)] -- ^ table of patterns\/terms
| Term c t :! Term c t -- ^ table selection
| Variants [Term c t] -- ^ variants
| Term c t :++ Term c t -- ^ concatenation
| Token t -- ^ single token
| Empty -- ^ empty string
| Wildcard -- ^ wildcard pattern variable
| Var Var -- ^ bound pattern variable
-- Res CIdent -- ^ resource identifier
-- Int Integer -- ^ integer
deriving (Eq, Ord, Show)
-- ** calculations on terms
(+.) :: Term c t -> Label -> Term c t
Variants terms +. lbl = variants $ map (+. lbl) terms
Rec record +. lbl = maybe err id $ lookup lbl record
where err = error $ "(+.): label not in record"
Arg arg cat path +. lbl = Arg arg cat (path ++. lbl)
term +. lbl = term :. lbl
(+!) :: (Eq c, Eq t) => Term c t -> Term c t -> Term c t
Variants terms +! pat = variants $ map (+! pat) terms
term +! Variants pats = variants $ map (term +!) pats
term +! arg@(Arg _ _ _) = term :! arg
Arg arg cat path +! pat = Arg arg cat (path ++! pat)
-- cannot handle tables with pattern variales or wildcards (yet):
term@(Tbl table) +! pat = maybe (term :! pat) id $ lookup pat table
term +! pat = term :! pat
(?++) :: Term c t -> Term c t -> Term c t
Variants terms ?++ term = variants $ map (?++ term) terms
term ?++ Variants terms = variants $ map (term ?++) terms
Empty ?++ term = term
term ?++ Empty = term
term1 ?++ term2 = term1 :++ term2
variants :: [Term c t] -> Term c t
variants terms0 = case concatMap flatten terms0 of
[term] -> term
terms -> Variants terms
where flatten (Variants ts) = ts
flatten t = [t]
-- ** enumerations
enumerateTerms :: (Eq c, Eq t) => Maybe (Term c t) -> LinType c t -> [Term c t]
enumerateTerms arg (StrT) = maybe err return arg
where err = error "enumeratePatterns: parameter type should not be string"
enumerateTerms arg (ConT _ terms) = terms
enumerateTerms arg (RecT rtype)
= liftM Rec $ mapM enumAssign rtype
where enumAssign (lbl, ctype) = liftM ((,) lbl) $ enumerateTerms arg ctype
enumerateTerms arg (TblT ptype ctype)
= liftM Tbl $ mapM enumCase $ enumeratePatterns ptype
where enumCase pat = liftM ((,) pat) $ enumerateTerms (fmap (+! pat) arg) ctype
enumeratePatterns :: (Eq c, Eq t) => LinType c t -> [Term c t]
enumeratePatterns t = enumerateTerms Nothing t
----------------------------------------------------------------------
-- * paths of record projections and table selections
newtype Path c t = Path [Either Label (Term c t)] deriving (Eq, Ord, Show)
emptyPath :: Path c t
emptyPath = Path []
-- ** calculations on paths
(++.) :: Path c t -> Label -> Path c t
Path path ++. lbl = Path (Left lbl : path)
(++!) :: Path c t -> Term c t -> Path c t
Path path ++! sel = Path (Right sel : path)
lintypeFollowPath :: Path c t -> LinType c t -> LinType c t
lintypeFollowPath (Path path) = follow path
where follow [] ctype = ctype
follow (Right pat : path) (TblT _ ctype) = follow path ctype
follow (Left lbl : path) (RecT rec)
= maybe err (follow path) $ lookup lbl rec
where err = error $ "lintypeFollowPath: label not in record type"
termFollowPath :: (Eq c, Eq t) => Path c t -> Term c t -> Term c t
termFollowPath (Path path) = follow (reverse path)
where follow [] term = term
follow (Right pat : path) term = follow path (term +! pat)
follow (Left lbl : path) term = follow path (term +. lbl)
lintype2paths :: (Eq c, Eq t) => Path c t -> LinType c t -> [Path c t]
lintype2paths path (ConT _ _) = []
lintype2paths path (StrT) = [ path ]
lintype2paths path (RecT rec) = concat [ lintype2paths (path ++. lbl) ctype |
(lbl, ctype) <- rec ]
lintype2paths path (TblT pt vt) = concat [ lintype2paths (path ++! pat) vt |
pat <- enumeratePatterns pt ]
----------------------------------------------------------------------
instance Print c => Print (Decl c) where
prt (Decl var cat args)
| null args = prVar ++ prt cat
| otherwise = "(" ++ prVar ++ prt cat ++ prtBefore " " args ++ ")"
where prVar | var == anyVar = ""
| otherwise = "?" ++ prt var ++ ":"
instance Print TTerm where
prt (con :@ args)
| null args = prt con
| otherwise = "(" ++ prt con ++ prtBefore " " args ++ ")"
prt (TVar var) = "?" ++ prt var
instance (Print c, Print t) => Print (LinType c t) where
prt (RecT rec) = "{" ++ prtPairList ":" "; " rec ++ "}"
prt (TblT t1 t2) = "(" ++ prt t1 ++ " => " ++ prt t2 ++ ")"
prt (ConT t ts) = prt t ++ "[" ++ prtSep "|" ts ++ "]"
prt (StrT) = "Str"
instance (Print c, Print t) => Print (Term c t) where
prt (Arg n c p) = prt c ++ prt n ++ prt p
prt (c :^ []) = prt c
prt (c :^ ts) = "(" ++ prt c ++ prtBefore " " ts ++ ")"
prt (Rec rec) = "{" ++ prtPairList "=" "; " rec ++ "}"
prt (Tbl tbl) = "[" ++ prtPairList "=>" "; " tbl ++ "]"
prt (Variants ts) = "{| " ++ prtSep " | " ts ++ " |}"
prt (t1 :++ t2) = prt t1 ++ "++" ++ prt t2
prt (Token t) = "'" ++ prt t ++ "'"
prt (Empty) = "[]"
prt (Wildcard) = "_"
prt (term :. lbl) = prt term ++ "." ++ prt lbl
prt (term :! sel) = prt term ++ "!" ++ prt sel
prt (Var var) = "?" ++ prt var
instance (Print c, Print t) => Print (Path c t) where
prt (Path path) = concatMap prtEither (reverse path)
where prtEither (Left lbl) = "." ++ prt lbl
prtEither (Right patt) = "!" ++ prt patt
|
