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118 lines
4.4 KiB
Haskell
118 lines
4.4 KiB
Haskell
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-- |
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-- Module : GF.Speech.PGFToCFG
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--
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-- Approximates PGF grammars with context-free grammars.
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----------------------------------------------------------------------
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module GF.Speech.PGFToCFG (bnfPrinter, pgfToCFG) where
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import PGF.CId
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import PGF.Data as PGF
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import PGF.Macros
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import GF.Infra.Ident
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import GF.Speech.CFG hiding (Symbol)
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import Data.Array.IArray as Array
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import Data.List
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import Data.Map (Map)
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import qualified Data.Map as Map
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import qualified Data.IntMap as IntMap
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import Data.Maybe
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import Data.Set (Set)
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import qualified Data.Set as Set
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bnfPrinter :: PGF -> CId -> String
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bnfPrinter = toBNF id
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toBNF :: (CFG -> CFG) -> PGF -> CId -> String
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toBNF f pgf cnc = prCFG $ f $ pgfToCFG pgf cnc
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type Profile = [Int]
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pgfToCFG :: PGF
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-> CId -- ^ Concrete syntax name
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-> CFG
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pgfToCFG pgf lang = mkCFG (showCId (lookStartCat pgf)) extCats (startRules ++ concatMap ruleToCFRule rules)
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where
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cnc = lookConcr pgf lang
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rules :: [(FId,Production)]
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rules = [(fcat,prod) | (fcat,set) <- IntMap.toList (PGF.pproductions cnc)
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, prod <- Set.toList set]
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fcatCats :: Map FId Cat
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fcatCats = Map.fromList [(fc, showCId c ++ "_" ++ show i)
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| (c,CncCat s e lbls) <- Map.toList (cnccats cnc),
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(fc,i) <- zip (range (s,e)) [1..]]
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fcatCat :: FId -> Cat
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fcatCat c = Map.findWithDefault ("Unknown_" ++ show c) c fcatCats
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fcatToCat :: FId -> LIndex -> Cat
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fcatToCat c l = fcatCat c ++ row
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where row = if catLinArity c == 1 then "" else "_" ++ show l
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-- gets the number of fields in the lincat for the given category
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catLinArity :: FId -> Int
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catLinArity c = maximum (1:[rangeSize (bounds rhs) | (CncFun _ rhs, _) <- topdownRules c])
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topdownRules cat = f cat []
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where
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f cat rules = maybe rules (Set.fold g rules) (IntMap.lookup cat (pproductions cnc))
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g (PApply funid args) rules = (cncfuns cnc ! funid,args) : rules
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g (PCoerce cat) rules = f cat rules
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extCats :: Set Cat
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extCats = Set.fromList $ map lhsCat startRules
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startRules :: [CFRule]
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startRules = [CFRule (showCId c) [NonTerminal (fcatToCat fc r)] (CFRes 0)
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| (c,CncCat s e lbls) <- Map.toList (cnccats cnc),
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fc <- range (s,e), not (isPredefFId fc),
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r <- [0..catLinArity fc-1]]
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ruleToCFRule :: (FId,Production) -> [CFRule]
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ruleToCFRule (c,PApply funid args) =
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[CFRule (fcatToCat c l) (mkRhs row) (profilesToTerm [fixProfile row n | n <- [0..length args-1]])
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| (l,seqid) <- Array.assocs rhs
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, let row = sequences cnc ! seqid
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, not (containsLiterals row)]
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where
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CncFun f rhs = cncfuns cnc ! funid
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mkRhs :: Array DotPos Symbol -> [CFSymbol]
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mkRhs = concatMap symbolToCFSymbol . Array.elems
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containsLiterals :: Array DotPos Symbol -> Bool
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containsLiterals row = not (null ([n | SymLit n _ <- Array.elems row] ++
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[n | SymVar n _ <- Array.elems row]))
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symbolToCFSymbol :: Symbol -> [CFSymbol]
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symbolToCFSymbol (SymCat n l) = [let PArg _ fid = args!!n in NonTerminal (fcatToCat fid l)]
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symbolToCFSymbol (SymKS ts) = map Terminal ts
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symbolToCFSymbol (SymKP ts as) = map Terminal $ ts
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---- ++ [t | Alt ss _ <- as, t <- ss]
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---- should be alternatives in [[CFSymbol]]
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---- AR 3/6/2010
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fixProfile :: Array DotPos Symbol -> Int -> Profile
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fixProfile row i = [k | (k,j) <- nts, j == i]
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where
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nts = zip [0..] [j | nt <- Array.elems row, j <- getPos nt]
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getPos (SymCat j _) = [j]
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getPos (SymLit j _) = [j]
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getPos _ = []
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profilesToTerm :: [Profile] -> CFTerm
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profilesToTerm ps = CFObj f (zipWith profileToTerm argTypes ps)
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where (argTypes,_) = catSkeleton $ lookType (abstract pgf) f
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profileToTerm :: CId -> Profile -> CFTerm
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profileToTerm t [] = CFMeta t
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profileToTerm _ xs = CFRes (last xs) -- FIXME: unify
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ruleToCFRule (c,PCoerce c') =
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[CFRule (fcatToCat c l) [NonTerminal (fcatToCat c' l)] (CFRes 0)
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| l <- [0..catLinArity c-1]]
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