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module Derive.Derivation(wantDerive, performDerive, writeDerive) where
import System.IO
import System.IO.Unsafe
import Language.Haskell
import Control.Arrow
import Control.Monad
import Data.List
import Derive.Utils
import Derive.Flags
import Data.Derive.Internal.Derivation
import qualified Data.Map as Map
---------------------------------------------------------------------
-- WHAT DO YOU WANT TO DERIVE
wantDerive :: [Flag] -> Module -> Module -> [Type]
wantDerive flag real mine = nub $ map fromTyParens $ wantDeriveFlag flag decls ++ wantDeriveAnnotation real mine
where decls = filter isDataDecl $ moduleDecls mine
wantDeriveFlag :: [Flag] -> [DataDecl] -> [Type]
wantDeriveFlag flags decls = [TyApp (tyCon x) d | Derive xs <- flags, x <- xs, d <- declst]
where declst = [tyApps (tyCon $ dataDeclName d) (map tyVar $ dataDeclVars d) | d <- decls]
wantDeriveAnnotation :: Module -> Module -> [Type]
wantDeriveAnnotation real mine = moduleDerives mine \\ moduleDerives real
moduleDerives :: Module -> [Type]
moduleDerives = concatMap f . moduleDecls
where
f (DataDecl _ _ _ name vars _ deriv) = g name vars deriv
f (GDataDecl _ _ _ name vars _ _ deriv) = g name vars deriv
f (DerivDecl _ _ name args) = [TyCon name `tyApps` args]
f _ = []
g name vars deriv = [TyCon a `tyApps` (b:bs) | (a,bs) <- deriv]
where b = TyCon (UnQual name) `tyApps` map (tyVar . prettyPrint) vars
---------------------------------------------------------------------
-- ACTUALLY DERIVE IT
performDerive :: [Derivation] -> Module -> [Type] -> [String]
performDerive derivations modu = concatMap ((:) "" . f)
where
grab = getDecl modu
g = getDerivation derivations
f ty = case d ty grab (moduleName modu, grab typ1Name) of
Left x -> unsafePerformIO $ let res = msg x in hPutStrLn stderr res >> return ["-- " ++ res]
Right x -> concatMap (lines . prettyPrint) x
where
d = derivationOp $ g clsName
(cls,typ1:_) = fromTyApps ty
clsName = prettyPrint cls
typ1Name = tyRoot typ1
msg x = "Deriving " ++ prettyPrint ty ++ ": " ++ x
getDecl :: Module -> (String -> Decl)
getDecl modu = \name -> Map.findWithDefault (error $ "Can't find data type definition for: " ++ name) name mp
where
mp = Map.fromList $ concatMap f $ moduleDecls modu
f x@(DataDecl _ _ _ name _ _ _) = [(prettyPrint name, x)]
f x@(GDataDecl _ _ _ name _ _ _ _) = [(prettyPrint name, x)]
f x@(TypeDecl _ name _ _) = [(prettyPrint name, x)]
f _ = []
getDerivation :: [Derivation] -> String -> Derivation
getDerivation derivations = \name -> Map.findWithDefault (error $ "Don't know how to derive type class: " ++ name) name mp
where
mp = Map.fromList $ map (derivationName &&& id) derivations
---------------------------------------------------------------------
-- WRITE IT BACK
writeDerive :: FilePath -> ModuleName -> [Flag] -> [String] -> IO ()
writeDerive file modu flags xs = do
-- force the output first, ensure that we don't crash half way through
() <- length (concat xs) `seq` return ()
let append = Append `elem` flags
let output = [x | Output x <- flags]
let ans = take 1 ["module " ++ x ++ " where" | Modu x <- reverse flags] ++
["import " ++ if null i then prettyPrint modu else i | Import i <- flags] ++
xs
when append $ do
src <- readFile' file
writeGenerated file ans
forM output $ \o -> writeFile o $ unlines ans
when (not append && null output) $ putStr $ unlines ans
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