forked from GitHub/gf-core
134 lines
4.5 KiB
Haskell
134 lines
4.5 KiB
Haskell
module GrammarToHaskell (grammar2haskell) where
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import qualified GFC
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import Macros
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import Modules
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import Operations
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-- to write a GF abstract grammar into a Haskell module with translations from
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-- data objects into GF trees. Example: GSyntax for Agda.
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-- AR 11/11/1999 -- 7/12/2000 -- 18/5/2004
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-- the main function
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grammar2haskell :: GFC.CanonGrammar -> String
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grammar2haskell gr = foldr (++++) [] $
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haskPreamble ++ [datatypes gr', gfinstances gr', fginstances gr']
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where gr' = hSkeleton gr
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-- by this you can prefix all identifiers with stg; the default is 'G'
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gId :: OIdent -> OIdent
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gId i = 'G':i
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haskPreamble =
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[
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"module GSyntax where",
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"",
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"import Ident",
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"import Grammar",
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"import PrGrammar",
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"import Macros",
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"import Operations",
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"----------------------------------------------------",
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"-- automatic translation from GF to Haskell",
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"----------------------------------------------------",
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"",
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"class Gf a where gf :: a -> Trm",
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"class Fg a where fg :: Trm -> a",
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"",
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predefInst "String" "K s",
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"",
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predefInst "Int" "EInt s",
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"",
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"----------------------------------------------------",
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"-- below this line machine-generated",
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"----------------------------------------------------",
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""
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]
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predefInst typ patt = let gtyp = gId typ in
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"newtype" +++ gtyp +++ "=" +++ gtyp +++ typ +++ " deriving Show" +++++
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"instance Gf" +++ gtyp +++ "where" ++++
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" gf (" ++ gtyp +++ "s) =" +++ patt +++++
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"instance Fg" +++ gtyp +++ "where" ++++
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" fg t =" ++++
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" case termForm t of" ++++
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" Ok ([]," +++ patt +++ ",[]) ->" +++ gtyp +++ "s" ++++
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" _ -> error (\"no" +++ gtyp +++ "\" ++ prt t)"
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type OIdent = String
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type HSkeleton = [(OIdent, [(OIdent, [OIdent])])]
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datatypes, gfinstances, fginstances :: (String,HSkeleton) -> String
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datatypes = (foldr (+++++) "") . (filter (/="")) . (map hDatatype) . snd
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gfinstances (m,g) = (foldr (+++++) "") $ (filter (/="")) $ (map (hInstance m)) g
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fginstances (m,g) = (foldr (+++++) "") $ (filter (/="")) $ (map (fInstance m)) g
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hDatatype :: (OIdent, [(OIdent, [OIdent])]) -> String
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hInstance, fInstance :: String -> (OIdent, [(OIdent, [OIdent])]) -> String
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hDatatype ("Cn",_) = "" ---
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hDatatype (cat,[]) = ""
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hDatatype (cat,rules) =
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"data" +++ gId cat +++ "=" ++
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(if length rules == 1 then "" else "\n ") +++
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foldr1 (\x y -> x ++ "\n |" +++ y)
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[gId f +++ foldr (+++) "" (map gId xx) | (f,xx) <- rules] ++++
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" deriving Show"
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----hInstance m ("Cn",_) = "" --- seems to belong to an old applic. AR 18/5/2004
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hInstance m (cat,[]) = ""
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hInstance m (cat,rules) =
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"instance Gf" +++ gId cat +++ "where" ++
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(if length rules == 1 then "" else "\n") +++
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foldr1 (\x y -> x ++ "\n" +++ y) [mkInst f xx | (f,xx) <- rules]
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where
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mkInst f xx =
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"gf " ++
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(if length xx == 0 then gId f else prParenth (gId f +++ foldr1 (+++) xx')) +++
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"=" +++
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"appqc \"" ++ m ++ "\" \"" ++ f ++ "\"" +++
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"[" ++ prTList ", " ["gf" +++ x | x <- xx'] ++ "]"
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where xx' = ["x" ++ show i | (_,i) <- zip xx [1..]]
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----fInstance m ("Cn",_) = "" ---
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fInstance m (cat,[]) = ""
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fInstance m (cat,rules) =
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"instance Fg" +++ gId cat +++ "where" ++++
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" fg t =" ++++
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" case termForm t of" ++++
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foldr1 (\x y -> x ++ "\n" ++ y) [mkInst f xx | (f,xx) <- rules] ++++
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" _ -> error (\"no" +++ cat ++ " \" ++ prt t)"
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where
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mkInst f xx =
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" Ok ([], Q (IC \"" ++ m ++ "\") (IC \"" ++ f ++ "\")," ++
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"[" ++ prTList "," xx' ++ "])" +++
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"->" +++
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gId f +++
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prTList " " [prParenth ("fg" +++ x) | x <- xx']
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where xx' = ["x" ++ show i | (_,i) <- zip xx [1..]]
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hSkeleton :: GFC.CanonGrammar -> (String,HSkeleton)
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hSkeleton gr = (name,collectR rules [(c,[]) | c <- cats]) where
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collectR rr hh =
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case rr of
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(fun,typ):rs -> case catSkeleton typ of
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Ok (cats,cat) ->
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collectR rs (updateSkeleton (symid (snd cat)) hh (fun,
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map (symid . snd) cats))
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_ -> collectR rs hh
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_ -> hh
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cats = [symid cat | (cat,GFC.AbsCat _ _) <- defs]
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rules = [(symid fun, typ) | (fun,GFC.AbsFun typ _) <- defs]
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defs = concat [tree2list (jments m) | im@(_,ModMod m) <- modules gr, isModAbs m]
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name = ifNull "UnknownModule" (symid . last) [n | (n,ModMod m) <- modules gr, isModAbs m]
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updateSkeleton :: OIdent -> HSkeleton -> (OIdent, [OIdent]) -> HSkeleton
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updateSkeleton cat skel rule =
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case skel of
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(cat0,rules):rr | cat0 == cat -> (cat0, rule:rules) : rr
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(cat0,rules):rr -> (cat0, rules) : updateSkeleton cat rr rule
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