module GF.Compile.PGFtoHaskell (grammar2haskell) where
import PGF(showCId)
import PGF.Internal
import GF.Data.Operations
import GF.Infra.Option
import Data.List(isPrefixOf,find,intercalate,intersperse,groupBy,sortBy)
import qualified Data.Map as Map
type Prefix = String -> String
type DerivingClause = String
-- | the main function
grammar2haskell :: Options
-> String -- ^ Module name.
-> PGF
-> String
grammar2haskell opts name gr = foldr (++++) [] $
pragmas ++ haskPreamble gadt name derivingClause (extraImports ++ pgfImports) ++
[types, gfinstances gId lexical gr'] ++ compos
where gr' = hSkeleton gr
gadt = haskellOption opts HaskellGADT
dataExt = haskellOption opts HaskellData
pgf2 = haskellOption opts HaskellPGF2
lexical cat = haskellOption opts HaskellLexical && isLexicalCat opts cat
gId | haskellOption opts HaskellNoPrefix = rmForbiddenChars
| otherwise = ("G"++) . rmForbiddenChars
-- GF grammars allow weird identifier names inside '', e.g. 'VP/Object'
rmForbiddenChars = filter (`notElem` "'!#$%&*+./<=>?@\\^|-~")
pragmas | gadt = ["{-# LANGUAGE GADTs, FlexibleInstances, KindSignatures, RankNTypes, TypeSynonymInstances #-}"]
| dataExt = ["{-# LANGUAGE DeriveDataTypeable #-}"]
| otherwise = []
derivingClause
| dataExt = "deriving (Show,Data)"
| otherwise = "deriving Show"
extraImports | gadt = ["import Control.Monad.Identity", "import Data.Monoid"]
| dataExt = ["import Data.Data"]
| otherwise = []
pgfImports | pgf2 = ["import PGF2 hiding (Tree)", "", "showCId :: CId -> String", "showCId = id"]
| otherwise = ["import PGF hiding (Tree)"]
types | gadt = datatypesGADT gId lexical gr'
| otherwise = datatypes gId derivingClause lexical gr'
compos | gadt = prCompos gId lexical gr' ++ composClass
| otherwise = []
haskPreamble :: Bool -> String -> String -> [String] -> [String]
haskPreamble gadt name derivingClause imports =
[
"module " ++ name ++ " where",
""
] ++ imports ++ [
"",
"----------------------------------------------------",
"-- automatic translation from GF to Haskell",
"----------------------------------------------------",
"",
"class Gf a where",
" gf :: a -> Expr",
" fg :: Expr -> a",
"",
predefInst gadt derivingClause "GString" "String" "unStr" "mkStr",
"",
predefInst gadt derivingClause "GInt" "Int" "unInt" "mkInt",
"",
predefInst gadt derivingClause "GFloat" "Double" "unFloat" "mkFloat",
"",
"----------------------------------------------------",
"-- below this line machine-generated",
"----------------------------------------------------",
""
]
predefInst :: Bool -> String -> String -> String -> String -> String -> String
predefInst gadt derivingClause gtyp typ destr consr =
(if gadt
then []
else "newtype" +++ gtyp +++ "=" +++ gtyp +++ typ +++ derivingClause ++ "\n\n"
)
++
"instance Gf" +++ gtyp +++ "where" ++++
" gf (" ++ gtyp +++ "x) =" +++ consr +++ "x" ++++
" fg t =" ++++
" case "++destr++" t of" ++++
" Just x -> " +++ gtyp +++ "x" ++++
" Nothing -> error (\"no" +++ gtyp +++ "\" ++ show t)"
type OIdent = String
type HSkeleton = [(OIdent, [(OIdent, [OIdent])])]
datatypes :: Prefix -> DerivingClause -> (OIdent -> Bool) -> (String,HSkeleton) -> String
datatypes gId derivingClause lexical = foldr (+++++) "" . filter (/="") . map (hDatatype gId derivingClause lexical) . snd
gfinstances :: Prefix -> (OIdent -> Bool) -> (String,HSkeleton) -> String
gfinstances gId lexical (m,g) = foldr (+++++) "" $ filter (/="") $ map (gfInstance gId lexical m) g
hDatatype :: Prefix -> DerivingClause -> (OIdent -> Bool) -> (OIdent, [(OIdent, [OIdent])]) -> String
hDatatype _ _ _ ("Cn",_) = "" ---
hDatatype gId _ _ (cat,[]) = "data" +++ gId cat
hDatatype gId derivingClause _ (cat,rules) | isListCat (cat,rules) =
"newtype" +++ gId cat +++ "=" +++ gId cat +++ "[" ++ gId (elemCat cat) ++ "]"
+++ derivingClause
hDatatype gId derivingClause lexical (cat,rules) =
"data" +++ gId cat +++ "=" ++
(if length rules == 1 then "" else "\n ") +++
foldr1 (\x y -> x ++ "\n |" +++ y) constructors ++++
" " +++ derivingClause
where
constructors = [gId f +++ foldr (+++) "" (map (gId) xx) | (f,xx) <- nonLexicalRules (lexical cat) rules]
++ if lexical cat then [lexicalConstructor cat +++ "String"] else []
nonLexicalRules :: Bool -> [(OIdent, [OIdent])] -> [(OIdent, [OIdent])]
nonLexicalRules False rules = rules
nonLexicalRules True rules = [r | r@(f,t) <- rules, not (null t)]
lexicalConstructor :: OIdent -> String
lexicalConstructor cat = "Lex" ++ cat
predefTypeSkel :: HSkeleton
predefTypeSkel = [(c,[]) | c <- ["String", "Int", "Float"]]
-- GADT version of data types
datatypesGADT :: Prefix -> (OIdent -> Bool) -> (String,HSkeleton) -> String
datatypesGADT gId lexical (_,skel) = unlines $
concatMap (hCatTypeGADT gId) (skel ++ predefTypeSkel) ++
[
"",
"data Tree :: * -> * where"
] ++
concatMap (map (" "++) . hDatatypeGADT gId lexical) skel ++
[
" GString :: String -> Tree GString_",
" GInt :: Int -> Tree GInt_",
" GFloat :: Double -> Tree GFloat_",
"",
"instance Eq (Tree a) where",
" i == j = case (i,j) of"
] ++
concatMap (map (" "++) . hEqGADT gId lexical) skel ++
[
" (GString x, GString y) -> x == y",
" (GInt x, GInt y) -> x == y",
" (GFloat x, GFloat y) -> x == y",
" _ -> False"
]
hCatTypeGADT :: Prefix -> (OIdent, [(OIdent, [OIdent])]) -> [String]
hCatTypeGADT gId (cat,rules)
= ["type"+++gId cat+++"="+++"Tree"+++gId cat++"_",
"data"+++gId cat++"_"]
hDatatypeGADT :: Prefix -> (OIdent -> Bool) -> (OIdent, [(OIdent, [OIdent])]) -> [String]
hDatatypeGADT gId lexical (cat, rules)
| isListCat (cat,rules) = [gId cat+++"::"+++"["++gId (elemCat cat)++"]" +++ "->" +++ t]
| otherwise =
[ gId f +++ "::" +++ concatMap (\a -> gId a +++ "-> ") args ++ t
| (f,args) <- nonLexicalRules (lexical cat) rules ]
++ if lexical cat then [lexicalConstructor cat +++ ":: String ->"+++ t] else []
where t = "Tree" +++ gId cat ++ "_"
hEqGADT :: Prefix -> (OIdent -> Bool) -> (OIdent, [(OIdent, [OIdent])]) -> [String]
hEqGADT gId lexical (cat, rules)
| isListCat (cat,rules) = let r = listr cat in ["(" ++ patt "x" r ++ "," ++ patt "y" r ++ ") -> " ++ listeqs]
| otherwise = ["(" ++ patt "x" r ++ "," ++ patt "y" r ++ ") -> " ++ eqs r | r <- nonLexicalRules (lexical cat) rules]
++ if lexical cat then ["(" ++ lexicalConstructor cat +++ "x" ++ "," ++ lexicalConstructor cat +++ "y" ++ ") -> x == y"] else []
where
patt s (f,xs) = unwords (gId f : mkSVars s (length xs))
eqs (_,xs) = unwords ("and" : "[" : intersperse "," [x ++ " == " ++ y |
(x,y) <- zip (mkSVars "x" (length xs)) (mkSVars "y" (length xs)) ] ++ ["]"])
listr c = (c,["foo"]) -- foo just for length = 1
listeqs = "and [x == y | (x,y) <- zip x1 y1]"
prCompos :: Prefix -> (OIdent -> Bool) -> (String,HSkeleton) -> [String]
prCompos gId lexical (_,catrules) =
["instance Compos Tree where",
" compos r a f t = case t of"]
++
[" " ++ prComposCons (gId f) xs | (c,rs) <- catrules, not (isListCat (c,rs)),
(f,xs) <- rs, not (null xs)]
++
[" " ++ prComposCons (gId c) ["x1"] | (c,rs) <- catrules, isListCat (c,rs)]
++
[" _ -> r t"]
where
prComposCons f xs = let vs = mkVars (length xs) in
f +++ unwords vs +++ "->" +++ rhs f (zip vs xs)
rhs f vcs = "r" +++ f +++ unwords (map (prRec f) vcs)
prRec f (v,c)
| isList f = "`a` foldr (a . a (r (:)) . f) (r [])" +++ v
| otherwise = "`a`" +++ "f" +++ v
isList f = gId "List" `isPrefixOf` f
gfInstance :: Prefix -> (OIdent -> Bool) -> String -> (OIdent, [(OIdent, [OIdent])]) -> String
gfInstance gId lexical m crs = hInstance gId lexical m crs ++++ fInstance gId lexical m crs
hInstance :: (String -> String) -> (String -> Bool) -> String -> (String, [(OIdent, [OIdent])]) -> String
----hInstance m ("Cn",_) = "" --- seems to belong to an old applic. AR 18/5/2004
hInstance gId _ m (cat,[]) = unlines [
"instance Show" +++ gId cat,
"",
"instance Gf" +++ gId cat +++ "where",
" gf _ = undefined",
" fg _ = undefined"
]
hInstance gId lexical m (cat,rules)
| isListCat (cat,rules) =
"instance Gf" +++ gId cat +++ "where" ++++
" gf (" ++ gId cat +++ "[" ++ intercalate "," baseVars ++ "])"
+++ "=" +++ mkRHS ("Base"++ec) baseVars ++++
" gf (" ++ gId cat +++ "(x:xs)) = "
++ mkRHS ("Cons"++ec) ["x",prParenth (gId cat+++"xs")]
-- no show for GADTs
-- ++++ " gf (" ++ gId cat +++ "xs) = error (\"Bad " ++ cat ++ " value: \" ++ show xs)"
| otherwise =
"instance Gf" +++ gId cat +++ "where\n" ++
unlines ([mkInst f xx | (f,xx) <- nonLexicalRules (lexical cat) rules]
++ if lexical cat then [" gf (" ++ lexicalConstructor cat +++ "x) = mkApp (mkCId x) []"] else [])
where
ec = elemCat cat
baseVars = mkVars (baseSize (cat,rules))
mkInst f xx = let xx' = mkVars (length xx) in " gf " ++
(if null xx then gId f else prParenth (gId f +++ foldr1 (+++) xx')) +++
"=" +++ mkRHS f xx'
mkRHS f vars = "mkApp (mkCId \"" ++ f ++ "\")" +++
"[" ++ prTList ", " ["gf" +++ x | x <- vars] ++ "]"
mkVars :: Int -> [String]
mkVars = mkSVars "x"
mkSVars :: String -> Int -> [String]
mkSVars s n = [s ++ show i | i <- [1..n]]
----fInstance m ("Cn",_) = "" ---
fInstance _ _ m (cat,[]) = ""
fInstance gId lexical m (cat,rules) =
" fg t =" ++++
(if isList
then " " ++ gId cat ++ " (fgs t) where\n fgs t = case unApp t of"
else " case unApp t of") ++++
unlines [mkInst f xx | (f,xx) <- nonLexicalRules (lexical cat) rules] ++++
(if lexical cat then " Just (i,[]) -> " ++ lexicalConstructor cat +++ "(showCId i)" else "") ++++
" _ -> error (\"no" +++ cat ++ " \" ++ show t)"
where
isList = isListCat (cat,rules)
mkInst f xx =
" Just (i," ++
"[" ++ prTList "," xx' ++ "])" +++
"| i == mkCId \"" ++ f ++ "\" ->" +++ mkRHS f xx'
where
xx' = ["x" ++ show i | (_,i) <- zip xx [1..]]
mkRHS f vars
| isList =
if "Base" `isPrefixOf` f
then "[" ++ prTList ", " [ "fg" +++ x | x <- vars ] ++ "]"
else "fg" +++ (vars !! 0) +++ ":" +++ "fgs" +++ (vars !! 1)
| otherwise =
gId f +++
prTList " " [prParenth ("fg" +++ x) | x <- vars]
--type HSkeleton = [(OIdent, [(OIdent, [OIdent])])]
hSkeleton :: PGF -> (String,HSkeleton)
hSkeleton gr =
(showCId (absname gr),
let fs =
[(showCId c, [(showCId f, map showCId cs) | (f, (cs,_)) <- fs]) |
fs@((_, (_,c)):_) <- fns]
in fs ++ [(sc, []) | c <- cts, let sc = showCId c, sc `notElem` (["Int", "Float", "String"] ++ map fst fs)]
)
where
cts = Map.keys (cats (abstract gr))
fns = groupBy valtypg (sortBy valtyps (map jty (Map.assocs (funs (abstract gr)))))
valtyps (_, (_,x)) (_, (_,y)) = compare x y
valtypg (_, (_,x)) (_, (_,y)) = x == y
jty (f,(ty,_,_,_)) = (f,catSkeleton ty)
{-
updateSkeleton :: OIdent -> HSkeleton -> (OIdent, [OIdent]) -> HSkeleton
updateSkeleton cat skel rule =
case skel of
(cat0,rules):rr | cat0 == cat -> (cat0, rule:rules) : rr
(cat0,rules):rr -> (cat0, rules) : updateSkeleton cat rr rule
-}
isListCat :: (OIdent, [(OIdent, [OIdent])]) -> Bool
isListCat (cat,rules) = "List" `isPrefixOf` cat && length rules == 2
&& ("Base"++c) `elem` fs && ("Cons"++c) `elem` fs
where
c = elemCat cat
fs = map fst rules
-- | Gets the element category of a list category.
elemCat :: OIdent -> OIdent
elemCat = drop 4
{-
isBaseFun :: OIdent -> Bool
isBaseFun f = "Base" `isPrefixOf` f
isConsFun :: OIdent -> Bool
isConsFun f = "Cons" `isPrefixOf` f
-}
baseSize :: (OIdent, [(OIdent, [OIdent])]) -> Int
baseSize (_,rules) = length bs
where Just (_,bs) = find (("Base" `isPrefixOf`) . fst) rules
composClass :: [String]
composClass =
[
"",
"class Compos t where",
" compos :: (forall a. a -> m a) -> (forall a b. m (a -> b) -> m a -> m b)",
" -> (forall a. t a -> m (t a)) -> t c -> m (t c)",
"",
"composOp :: Compos t => (forall a. t a -> t a) -> t c -> t c",
"composOp f = runIdentity . composOpM (Identity . f)",
"",
"composOpM :: (Compos t, Monad m) => (forall a. t a -> m (t a)) -> t c -> m (t c)",
"composOpM = compos return ap",
"",
"composOpM_ :: (Compos t, Monad m) => (forall a. t a -> m ()) -> t c -> m ()",
"composOpM_ = composOpFold (return ()) (>>)",
"",
"composOpMonoid :: (Compos t, Monoid m) => (forall a. t a -> m) -> t c -> m",
"composOpMonoid = composOpFold mempty mappend",
"",
"composOpMPlus :: (Compos t, MonadPlus m) => (forall a. t a -> m b) -> t c -> m b",
"composOpMPlus = composOpFold mzero mplus",
"",
"composOpFold :: Compos t => b -> (b -> b -> b) -> (forall a. t a -> b) -> t c -> b",
"composOpFold z c f = unC . compos (\\_ -> C z) (\\(C x) (C y) -> C (c x y)) (C . f)",
"",
"newtype C b a = C { unC :: b }"
]