Files
gf-core/src/GF/Formalism/GCFG.hs
2005-05-09 08:25:56 +00:00

52 lines
1.7 KiB
Haskell

----------------------------------------------------------------------
-- |
-- Maintainer : PL
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/05/09 09:28:44 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.3 $
--
-- Basic GCFG formalism (derived from Pollard 1984)
-----------------------------------------------------------------------------
module GF.Formalism.GCFG where
import GF.Formalism.Utilities (SyntaxChart)
import GF.Data.Assoc (assocMap, accumAssoc)
import GF.Data.SortedList (nubsort, groupPairs)
import GF.Infra.Print
----------------------------------------------------------------------
type Grammar c n l t = [Rule c n l t]
data Rule c n l t = Rule (Abstract c n) (Concrete l t)
deriving (Eq, Ord, Show)
data Abstract cat name = Abs cat [cat] name
deriving (Eq, Ord, Show)
data Concrete lin term = Cnc lin [lin] term
deriving (Eq, Ord, Show)
abstract2chart :: (Ord n, Ord e) => [Abstract e n] -> SyntaxChart n e
abstract2chart rules = accumAssoc groupPairs $
[ (e, (n, es)) | Abs e es n <- rules ]
----------------------------------------------------------------------
instance (Print c, Print n, Print l, Print t) => Print (Rule n c l t) where
prt (Rule abs cnc) = prt abs ++ " := " ++ prt cnc
prtList = prtSep "\n"
instance (Print c, Print n) => Print (Abstract c n) where
prt (Abs cat args name) = prt name ++ ". " ++ prt cat ++
( if null args then ""
else " -> " ++ prtSep " " args )
instance (Print l, Print t) => Print (Concrete l t) where
prt (Cnc lcat args term) = prt term
++ " : " ++ prt lcat ++
( if null args then ""
else " / " ++ prtSep " " args)