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|
----------------------------------------------------------------------
-- |
-- Module : GF.Speech.PGFToCFG
--
-- Approximates PGF grammars with context-free grammars.
----------------------------------------------------------------------
module GF.Speech.PGFToCFG (pgfToCFG) where
import PGF.CId
import PGF.Data as PGF
import PGF.Macros
import GF.Infra.Ident
import GF.Speech.CFG
import Data.Array as Array
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Maybe
import Data.Set (Set)
import qualified Data.Set as Set
pgfToCFG :: PGF
-> CId -- ^ Concrete syntax name
-> CFG
pgfToCFG pgf lang = mkCFG (lookStartCat pgf) extCats (startRules ++ concatMap fruleToCFRule rules)
where
pinfo = fromMaybe (error "pgfToCFG: No parser.") (lookParser pgf lang)
rules :: [FRule]
rules = Array.elems (PGF.allRules pinfo)
fcatGFCats :: Map FCat CId
fcatGFCats = Map.fromList [(fc,c) | (c,fcs) <- Map.toList (startupCats pinfo), fc <- fcs]
fcatGFCat :: FCat -> CId
fcatGFCat c = fromMaybe (mkCId "Unknown") (Map.lookup c fcatGFCats)
fcatToCat :: FCat -> FIndex -> Cat
fcatToCat c l = prCId (fcatGFCat c) ++ "_" ++ show c ++ "_" ++ show l
extCats :: Set Cat
extCats = Set.fromList $ map lhsCat startRules
-- NOTE: this is only correct for cats that have a lincat with exactly one row.
startRules :: [CFRule]
startRules = [CFRule (prCId c) [NonTerminal (fcatToCat fc 0)] (CFRes 0)
| (c,fcs) <- Map.toList (startupCats pinfo), fc <- fcs]
fruleToCFRule :: FRule -> [CFRule]
fruleToCFRule (FRule f ps args c rhs) =
[CFRule (fcatToCat c l) (mkRhs row) (profilesToTerm (map (fixProfile row) ps))
| (l,row) <- Array.assocs rhs]
where
mkRhs :: Array FPointPos FSymbol -> [CFSymbol]
mkRhs = map fsymbolToSymbol . Array.elems
fsymbolToSymbol :: FSymbol -> CFSymbol
fsymbolToSymbol (FSymCat l n) = NonTerminal (fcatToCat (args!!n) l)
fsymbolToSymbol (FSymTok t) = Terminal t
fixProfile :: Array FPointPos FSymbol -> Profile -> Profile
fixProfile row = concatMap positions
where
nts = zip [0..] [nt | nt@(FSymCat _ _) <- Array.elems row ]
positions i = [k | (k,FSymCat _ j) <- nts, j == i]
profilesToTerm :: [Profile] -> CFTerm
profilesToTerm [[n]] | f == wildCId = CFRes n
profilesToTerm ps = CFObj f (zipWith profileToTerm argTypes ps)
where (argTypes,_) = catSkeleton $ lookType pgf f
profileToTerm :: CId -> Profile -> CFTerm
profileToTerm t [] = CFMeta t
profileToTerm _ xs = CFRes (last xs) -- FIXME: unify
|
