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|
----------------------------------------------------------------------
-- |
-- Maintainer : PL
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/04/14 18:41:21 $
-- > CVS $Author: peb $
-- > CVS $Revision: 1.1 $
--
-- Instantiating all types which only have one single element.
--
-- Should be merged into 'GF.Conversion.FiniteToSimple'
-----------------------------------------------------------------------------
module GF.Conversion.RemoveSingletons where
import GF.System.Tracing
import GF.Infra.Print
import GF.Formalism.Utilities
import GF.Formalism.GCFG
import GF.Formalism.SimpleGFC
import GF.Conversion.Types
import GF.Data.SortedList
import GF.Data.Assoc
import List (mapAccumL)
convertGrammar :: SGrammar -> SGrammar
convertGrammar grammar = if singles == emptyAssoc then grammar
else tracePrt "#singleton-removed rules" (prt . length) $
map (convertRule singles) grammar
where singles = calcSingletons grammar
convertRule :: Assoc SCat (SyntaxForest Fun, Maybe STerm) -> SRule -> SRule
convertRule singles rule@(Rule (Abs _ decls _) _)
= if all (Nothing ==) singleArgs then rule
else instantiateSingles singleArgs rule
where singleArgs = map (lookupAssoc singles . decl2cat) decls
instantiateSingles :: [Maybe (SyntaxForest Fun, Maybe STerm)] -> SRule -> SRule
instantiateSingles singleArgs (Rule (Abs decl decls (Name fun profile)) (Cnc lcat lcats lterm))
= Rule (Abs decl decls' (Name fun profile')) (Cnc lcat lcats' lterm')
where (decls', lcats') = unzip [ (d, l) | (Nothing, d, l) <- zip3 singleArgs decls lcats ]
profile' = map (fmap fst) exProfile `composeProfiles` profile
newArgs = map (fmap snd) exProfile
lterm' = fmap (instantiateLin newArgs) lterm
exProfile = snd $ mapAccumL mkProfile 0 singleArgs
mkProfile nr (Just trm) = (nr, Constant trm)
mkProfile nr (Nothing) = (nr+1, Unify [nr])
instantiateLin :: [Profile (Maybe STerm)] -> STerm -> STerm
instantiateLin newArgs = inst
where inst (Arg nr cat path)
= case newArgs !! nr of
Unify [nr'] -> Arg nr' cat path
Constant (Just term) -> termFollowPath path term
Constant Nothing -> error "instantiateLin: argument has no linearization"
inst (cn :^ terms) = cn :^ map inst terms
inst (Rec rec) = Rec [ (lbl, inst term) | (lbl, term) <- rec ]
inst (term :. lbl) = inst term +. lbl
inst (Tbl tbl) = Tbl [ (pat, inst term) | (pat, term) <- tbl ]
inst (term :! sel) = inst term +! inst sel
inst (Variants ts) = variants (map inst ts)
inst (t1 :++ t2) = inst t1 ?++ inst t2
inst term = term
----------------------------------------------------------------------
calcSingletons :: SGrammar -> Assoc SCat (SyntaxForest Fun, Maybe STerm)
calcSingletons rules = listAssoc singleCats
where singleCats = tracePrt "singleton cats" (prtSep " ") $
[ (cat, (constantNameToForest name, lin)) |
(cat, [([], name, lin)]) <- rulesByCat ]
rulesByCat = groupPairs $ nubsort
[ (decl2cat cat, (args, name, lin)) |
Rule (Abs cat args name) (Cnc _ _ lin) <- rules ]
|
