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|
----------------------------------------------------------------------
-- |
-- Module : GrammarToHaskell
-- Maintainer : Aarne Ranta
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/06/17 12:39:07 $
-- > CVS $Author: bringert $
-- > CVS $Revision: 1.8 $
--
-- to write a GF abstract grammar into a Haskell module with translations from
-- data objects into GF trees. Example: GSyntax for Agda.
-- AR 11/11/1999 -- 7/12/2000 -- 18/5/2004
-----------------------------------------------------------------------------
module GF.API.GrammarToHaskell (grammar2haskell, grammar2haskellGADT) where
import qualified GF.Canon.GFC as GFC
import GF.Grammar.Macros
import GF.Infra.Modules
import GF.Data.Operations
import Data.List (isPrefixOf, find, intersperse)
import Data.Maybe (fromMaybe)
-- | the main function
grammar2haskell :: GFC.CanonGrammar -> String
grammar2haskell gr = foldr (++++) [] $
haskPreamble ++ [datatypes gr', gfinstances gr', fginstances gr']
where gr' = hSkeleton gr
grammar2haskellGADT :: GFC.CanonGrammar -> String
grammar2haskellGADT gr = foldr (++++) [] $
["{-# OPTIONS_GHC -fglasgow-exts #-}"] ++
haskPreamble ++ [datatypesGADT gr', composInstance gr', showInstanceGADT gr',
gfinstances gr', fginstances gr']
where gr' = hSkeleton gr
-- | by this you can prefix all identifiers with stg; the default is 'G'
gId :: OIdent -> OIdent
gId i = 'G':i
haskPreamble =
[
"module GSyntax where",
"",
"import GF.Infra.Ident",
"import GF.Grammar.Grammar",
"import GF.Grammar.PrGrammar",
"import GF.Grammar.Macros",
"import GF.Data.Compos",
"import GF.Data.Operations",
"",
"import Control.Applicative (pure,(<*>))",
"import Data.Traversable (traverse)",
"----------------------------------------------------",
"-- automatic translation from GF to Haskell",
"----------------------------------------------------",
"",
"class Gf a where gf :: a -> Trm",
"class Fg a where fg :: Trm -> a",
"",
predefInst "GString" "String" "K s",
"",
predefInst "GInt" "Integer" "EInt s",
"",
predefInst "GFloat" "Double" "EFloat s",
"",
"----------------------------------------------------",
"-- below this line machine-generated",
"----------------------------------------------------",
""
]
predefInst gtyp typ patt =
"newtype" +++ gtyp +++ "=" +++ gtyp +++ typ +++ " deriving Show" +++++
"instance Gf" +++ gtyp +++ "where" ++++
" gf (" ++ gtyp +++ "s) =" +++ patt +++++
"instance Fg" +++ gtyp +++ "where" ++++
" fg t =" ++++
" case termForm t of" ++++
" Ok ([]," +++ patt +++ ",[]) ->" +++ gtyp +++ "s" ++++
" _ -> error (\"no" +++ gtyp +++ "\" ++ prt t)"
type OIdent = String
type HSkeleton = [(OIdent, [(OIdent, [OIdent])])]
datatypes, gfinstances, fginstances :: (String,HSkeleton) -> String
datatypes = (foldr (+++++) "") . (filter (/="")) . (map hDatatype) . snd
gfinstances (m,g) = (foldr (+++++) "") $ (filter (/="")) $ (map (hInstance m)) g
fginstances (m,g) = (foldr (+++++) "") $ (filter (/="")) $ (map (fInstance m)) g
hDatatype :: (OIdent, [(OIdent, [OIdent])]) -> String
hInstance, fInstance :: String -> (OIdent, [(OIdent, [OIdent])]) -> String
hDatatype ("Cn",_) = "" ---
hDatatype (cat,[]) = ""
hDatatype (cat,rules) | isListCat (cat,rules) =
"newtype" +++ gId cat +++ "=" +++ gId cat +++ "[" ++ gId (elemCat cat) ++ "]"
+++ "deriving Show"
hDatatype (cat,rules) =
"data" +++ gId cat +++ "=" ++
(if length rules == 1 then "" else "\n ") +++
foldr1 (\x y -> x ++ "\n |" +++ y)
[gId f +++ foldr (+++) "" (map gId xx) | (f,xx) <- rules] ++++
" deriving Show"
-- GADT version of data types
datatypesGADT :: (String,HSkeleton) -> String
datatypesGADT (_,skel) =
unlines (concatMap hCatTypeGADT skel)
+++++
"data Tree :: * -> * where" ++++ unlines (concatMap (map (" "++) . hDatatypeGADT) skel)
hCatTypeGADT :: (OIdent, [(OIdent, [OIdent])]) -> [String]
hCatTypeGADT (cat,rules)
= ["type"+++gId cat+++"="+++"Tree"+++gId cat++"_",
"data"+++gId cat++"_"]
hDatatypeGADT :: (OIdent, [(OIdent, [OIdent])]) -> [String]
hDatatypeGADT (cat, rules)
| isListCat (cat,rules) = [gId cat+++"::"+++"["++gId (elemCat cat)++"]" +++ "->" +++ t]
| otherwise =
[ gId f +++ "::" +++ concatMap (\a -> gId a +++ "-> ") args ++ t | (f,args) <- rules ]
where t = "Tree" +++ gId cat ++ "_"
----hInstance m ("Cn",_) = "" --- seems to belong to an old applic. AR 18/5/2004
hInstance m (cat,[]) = ""
hInstance m (cat,rules)
| isListCat (cat,rules) =
"instance Gf" +++ gId cat +++ "where" ++++
" gf (" ++ gId cat +++ "[" ++ concat (intersperse "," 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" ++
(if length rules == 1 then "" else "\n") +++
foldr1 (\x y -> x ++ "\n" +++ y) [mkInst f xx | (f,xx) <- rules]
where
ec = elemCat cat
baseVars = mkVars (baseSize (cat,rules))
mkInst f xx = let xx' = mkVars (length xx) in "gf " ++
(if length xx == 0 then gId f else prParenth (gId f +++ foldr1 (+++) xx')) +++
"=" +++ mkRHS f xx'
mkVars n = ["x" ++ show i | i <- [1..n]]
mkRHS f vars = "appqc \"" ++ m ++ "\" \"" ++ f ++ "\"" +++
"[" ++ prTList ", " ["gf" +++ x | x <- vars] ++ "]"
----fInstance m ("Cn",_) = "" ---
fInstance m (cat,[]) = ""
fInstance m (cat,rules) =
"instance Fg" +++ gId cat +++ "where" ++++
" fg t =" ++++
" case termForm t of" ++++
foldr1 (\x y -> x ++ "\n" ++ y) [mkInst f xx | (f,xx) <- rules] ++++
" _ -> error (\"no" +++ cat ++ " \" ++ prt t)"
where
mkInst f xx =
" Ok ([], Q (IC \"" ++ m ++ "\") (IC \"" ++ f ++ "\")," ++
"[" ++ prTList "," xx' ++ "])" +++
"->" +++ mkRHS f xx'
where xx' = ["x" ++ show i | (_,i) <- zip xx [1..]]
mkRHS f vars
| isListCat (cat,rules) =
if "Base" `isPrefixOf` f then
gId cat +++ "[" ++ prTList ", " [ "fg" +++ x | x <- vars ] ++ "]"
else
let (i,t) = (init vars,last vars)
in "let" +++ gId cat +++ "xs = fg " ++ t +++ "in" +++
gId cat +++ prParenth (prTList ":" (["fg"+++v | v <- i] ++ ["xs"]))
| otherwise =
gId f +++
prTList " " [prParenth ("fg" +++ x) | x <- vars]
composInstance :: (String,HSkeleton) -> String
composInstance (_,skel) = unlines $
["instance Compos Tree where",
" compos f t = case t of"]
++ map (" "++) (concatMap prComposCat skel
++ if not allRecursive then ["_ -> pure t"] else [])
where
prComposCat c@(cat, fs)
| isListCat c = [gId cat +++ "xs" +++ "->"
+++ "pure" +++ gId cat +++ "<*> traverse f" +++ "xs"]
| otherwise = concatMap (prComposFun cat) fs
prComposFun :: OIdent -> (OIdent,[OIdent]) -> [String]
prComposFun cat c@(fun,args)
| any isTreeType args = [gId fun +++ unwords vars +++ "->" +++ rhs]
| otherwise = []
where vars = ["x" ++ show n | n <- [1..length args]]
rhs = "pure" +++ gId fun +++ unwords (zipWith prRec vars args)
where prRec var typ
| not (isTreeType typ) = "<*>" +++ "pure" +++ var
| otherwise = "<*>" +++ "f" +++ var
allRecursive = and [any isTreeType args | (_,fs) <- skel, (_,args) <- fs]
isTreeType cat = cat `elem` (map fst skel ++ builtin)
isList cat = case filter ((==cat) . fst) skel of
[] -> error $ "Unknown cat " ++ show cat
x:_ -> isListCat x
builtin = ["GString", "GInt", "GFloat"]
showInstanceGADT :: (String,HSkeleton) -> String
showInstanceGADT (_,skel) = unlines $
["instance Show (Tree c) where",
" showsPrec n t = case t of"]
++ map (" "++) (concatMap prShowCat skel)
++ [" where opar n = if n > 0 then showChar '(' else id",
" cpar n = if n > 0 then showChar ')' else id"]
where
prShowCat c@(cat, fs)
| isListCat c = [gId cat +++ "xs" +++ "->" +++ "showList" +++ "xs"]
| otherwise = map (prShowFun cat) fs
prShowFun :: OIdent -> (OIdent,[OIdent]) -> String
prShowFun cat (fun,args)
| null vars = gId fun +++ "->" +++ "showString" +++ show fun
| otherwise = gId fun +++ unwords vars +++ "->"
+++ "opar n . showString" +++ show fun
+++ unwords [". showChar ' ' . showsPrec 1 " ++ x | x <- vars]
+++ ". cpar n"
where vars = ["x" ++ show n | n <- [1..length args]]
hSkeleton :: GFC.CanonGrammar -> (String,HSkeleton)
hSkeleton gr = (name,collectR rules [(c,[]) | c <- cats]) where
collectR rr hh =
case rr of
(fun,typ):rs -> case catSkeleton typ of
Ok (cats,cat) ->
collectR rs (updateSkeleton (symid (snd cat)) hh (fun,
map (symid . snd) cats))
_ -> collectR rs hh
_ -> hh
cats = [symid cat | (cat,GFC.AbsCat _ _) <- defs]
rules = [(symid fun, typ) | (fun,GFC.AbsFun typ _) <- defs]
defs = concat [tree2list (jments m) | im@(_,ModMod m) <- modules gr, isModAbs m]
name = ifNull "UnknownModule" (symid . last) [n | (n,ModMod m) <- modules gr, isModAbs m]
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
|
