{- Expands template haskell splices - - You should probably just use http://hackage.haskell.org/package/zeroth - instead. I wish I had known about it before writing this. - - First, the code must be built with a ghc that supports TH, - and the splices dumped to a log. For example: - cabal build --ghc-options=-ddump-splices 2>&1 | tee log - - Along with the log, a headers file may also be provided, containing - additional imports needed by the template haskell code. - - This program will parse the log, and expand all splices therein, - writing files to the specified destdir (which can be "." to modify - the source tree directly). They can then be built a second - time, with a ghc that does not support TH. - - Note that template haskell code may refer to symbols that are not - exported by the library that defines the TH code. In this case, - the library has to be modifed to export those symbols. - - There can also be other problems with the generated code; it may - need modifications to compile. - - - Copyright 2013 Joey Hess - - Licensed under the GNU GPL version 3 or higher. -} module Main where import Text.Parsec import Text.Parsec.String import Control.Applicative ((<$>)) import Data.Either import Data.List hiding (find) import Data.String.Utils import Data.Char import System.Environment import System.FilePath import System.Directory import System.IO import Control.Monad import Prelude hiding (log) import Utility.Monad import Utility.Misc import Utility.Exception import Utility.Path import Utility.FileSystemEncoding data Coord = Coord { coordLine :: Int , coordColumn :: Int } deriving (Read, Show) offsetCoord :: Coord -> Coord -> Coord offsetCoord a b = Coord (coordLine a - coordLine b) (coordColumn a - coordColumn b) data SpliceType = SpliceExpression | SpliceDeclaration deriving (Read, Show, Eq) data Splice = Splice { splicedFile :: FilePath , spliceStart :: Coord , spliceEnd :: Coord , splicedExpression :: String , splicedCode :: String , spliceType :: SpliceType } deriving (Read, Show) isExpressionSplice :: Splice -> Bool isExpressionSplice s = spliceType s == SpliceExpression number :: Parser Int number = read <$> many1 digit {- A pair of Coords is written in one of three ways: - "95:21-73", "1:1", or "(92,25)-(94,2)" -} coordsParser :: Parser (Coord, Coord) coordsParser = (try singleline <|> try weird <|> multiline) "Coords" where singleline = do line <- number void $ char ':' startcol <- number void $ char '-' endcol <- number return $ (Coord line startcol, Coord line endcol) weird = do line <- number void $ char ':' col <- number return $ (Coord line col, Coord line col) multiline = do start <- fromparens void $ char '-' end <- fromparens return $ (start, end) fromparens = between (char '(') (char ')') $ do line <- number void $ char ',' col <- number return $ Coord line col indent :: Parser String indent = many1 $ char ' ' restOfLine :: Parser String restOfLine = newline `after` many (noneOf "\n") indentedLine :: Parser String indentedLine = indent >> restOfLine spliceParser :: Parser Splice spliceParser = do file <- many1 (noneOf ":\n") void $ char ':' (start, end) <- coordsParser void $ string ": Splicing " splicetype <- tosplicetype <$> (string "expression" <|> string "declarations") void newline getthline <- expressionextractor expression <- unlines <$> many1 getthline void indent void $ string "======>" void newline getcodeline <- expressionextractor realcoords <- try (Right <$> getrealcoords file) <|> (Left <$> getcodeline) codelines <- many getcodeline return $ case realcoords of Left firstcodeline -> Splice file start end expression (unlines $ firstcodeline:codelines) splicetype Right (realstart, realend) -> Splice file realstart realend expression (unlines codelines) splicetype where tosplicetype "declarations" = SpliceDeclaration tosplicetype "expression" = SpliceExpression tosplicetype s = error $ "unknown splice type: " ++ s {- All lines of the indented expression start with the same - indent, which is stripped. Any other indentation is preserved. -} expressionextractor = do i <- lookAhead indent return $ try $ do void $ string i restOfLine {- When splicing declarations, GHC will output a splice - at 1:1, and then inside the splice code block, - the first line will give the actual coordinates of the - line that was spliced. -} getrealcoords file = do void indent void $ string file void $ char ':' char '\n' `after` coordsParser {- Extracts the splices, ignoring the rest of the compiler output. -} splicesExtractor :: Parser [Splice] splicesExtractor = rights <$> many extract where extract = try (Right <$> spliceParser) <|> (Left <$> compilerJunkLine) compilerJunkLine = restOfLine {- Modifies the source file, expanding the splices, which all must - have the same splicedFile. Writes the new file to the destdir. - - Each splice's Coords refer to the original position in the file, - and not to its position after any previous splices may have inserted - or removed lines. - - To deal with this complication, the file is broken into logical lines - (which can contain any String, including a multiline or empty string). - Each splice is assumed to be on its own block of lines; two - splices on the same line is not currently supported. - This means that a splice can modify the logical lines within its block - as it likes, without interfering with the Coords of other splices. - - As well as expanding splices, this can add a block of imports to the - file. These are put right before the first line in the file that - starts with "import " -} applySplices :: FilePath -> Maybe String -> [Splice] -> IO () applySplices _ _ [] = noop applySplices destdir imports splices@(first:_) = do let f = splicedFile first let dest = (destdir f) lls <- map (++ "\n") . lines <$> readFileStrictAnyEncoding f createDirectoryIfMissing True (parentDir dest) let newcontent = concat $ addimports $ expand lls splices oldcontent <- catchMaybeIO $ readFileStrictAnyEncoding dest when (oldcontent /= Just newcontent) $ do putStrLn $ "splicing " ++ f withFile dest WriteMode $ \h -> do fileEncoding h hPutStr h newcontent hClose h where expand lls [] = lls expand lls (s:rest) | isExpressionSplice s = expand (expandExpressionSplice s lls) rest | otherwise = expand (expandDeclarationSplice s lls) rest addimports lls = case imports of Nothing -> lls Just v -> let (start, end) = break ("import " `isPrefixOf`) lls in if null end then start else concat [ start , [v] , end ] {- Declaration splices are expanded to replace their whole line. -} expandDeclarationSplice :: Splice -> [String] -> [String] expandDeclarationSplice s lls = concat [before, [splice], end] where cs = spliceStart s ce = spliceEnd s (before, rest) = splitAt (coordLine cs - 1) lls (_oldlines, end) = splitAt (1 + coordLine (offsetCoord ce cs)) rest splice = mangleCode $ splicedCode s {- Expression splices are expanded within their line. -} expandExpressionSplice :: Splice -> [String] -> [String] expandExpressionSplice sp lls = concat [before, spliced:padding, end] where cs = spliceStart sp ce = spliceEnd sp (before, rest) = splitAt (coordLine cs - 1) lls (oldlines, end) = splitAt (1 + coordLine (offsetCoord ce cs)) rest (splicestart, padding, spliceend) = case map expandtabs oldlines of ss:r | null r -> (ss, [], ss) | otherwise -> (ss, take (length r) (repeat []), last r) _ -> ([], [], []) spliced = concat [ joinsplice $ deqqstart $ take (coordColumn cs - 1) splicestart , addindent (findindent splicestart) (mangleCode $ splicedCode sp) , deqqend $ drop (coordColumn ce) spliceend ] {- coordinates assume tabs are expanded to 8 spaces -} expandtabs = replace "\t" (take 8 $ repeat ' ') {- splicing leaves $() quasiquote behind; remove it -} deqqstart s = case reverse s of ('(':'$':restq) -> reverse restq _ -> s deqqend (')':s) = s deqqend s = s {- Prepare the code that comes just before the splice so - the splice will combine with it appropriately. -} joinsplice s -- all indentation? Skip it, we'll use the splice's indentation | all isSpace s = "" -- function definition needs no preparation -- ie: foo = $(splice) | "=" `isSuffixOf` s' = s -- nor does lambda definition or case expression | "->" `isSuffixOf` s' = s -- nor does a let .. in declaration | "in" `isSuffixOf` s' = s -- already have a $ to set off the splice -- ie: foo $ $(splice) | "$" `isSuffixOf` s' = s -- need to add a $ to set off the splice -- ie: bar $(splice) | otherwise = s ++ " $ " where s' = filter (not . isSpace) s findindent = length . takeWhile isSpace addindent n = unlines . map (i ++) . lines where i = take n $ repeat ' ' {- Tweaks code output by GHC in splices to actually build. Yipes. -} mangleCode :: String -> String mangleCode = flip_colon . remove_unnecessary_type_signatures . lambdaparenhack . lambdaparens . declaration_parens . case_layout . case_layout_multiline . yesod_url_render_hack . text_builder_hack . nested_instances . boxed_fileembed . collapse_multiline_strings . remove_package_version . emptylambda where {- Lambdas are often output without parens around them. - This breaks when the lambda is immediately applied to a - parameter. - - For example: - - renderRoute (StaticR sub_a1nUH) - = \ (a_a1nUI, b_a1nUJ) - -> (((pack "static") : a_a1nUI), - b_a1nUJ) - (renderRoute sub_a1nUH) - - There are sometimes many lines of lambda code that need to be - parenthesised. Approach: find the "->" and scan down the - column to the first non-whitespace. This is assumed - to be the expression after the lambda. - - Runs recursively on the body of the lambda, to handle nested - lambdas. -} lambdaparens = parsecAndReplace $ do -- skip lambdas inside tuples or parens prefix <- noneOf "(, \n" preindent <- many1 $ oneOf " \n" void $ string "\\ " lambdaparams <- restofline continuedlambdaparams <- many $ try $ do indent1 <- many1 $ char ' ' p <- satisfy isLetter aram <- many $ satisfy isAlphaNum <|> oneOf "_" void newline return $ indent1 ++ p:aram ++ "\n" indent1 <- many1 $ char ' ' void $ string "-> " firstline <- restofline lambdalines <- many $ try $ do void $ string indent1 void $ char ' ' l <- restofline return $ indent1 ++ " " ++ l return $ concat [ prefix:preindent , "(\\ " ++ lambdaparams ++ "\n" , concat continuedlambdaparams , indent1 ++ "-> " , lambdaparens $ intercalate "\n" (firstline:lambdalines) , ")\n" ] {- Hack to add missing parens in a specific case in yesod - static route code. - - StaticR - yesod_dispatch_env_a4iDV - (\ p_a4iE2 r_a4iE3 - -> r_a4iE3 - {Network.Wai.pathInfo = p_a4iE2} - xrest_a4iDT req_a4iDW)) } - - Need to add another paren around the lambda, and close it - before its parameters. lambdaparens misses this one because - there is already one paren present. - - Note that the { } may be on the same line, or wrapped to next. - - FIXME: This is a hack. lambdaparens could just always add a - layer of parens even when a lambda seems to be in parent. -} lambdaparenhack = parsecAndReplace $ do indent1 <- many1 $ char ' ' staticr <- string "StaticR" void newline void $ string indent1 yesod_dispatch_env <- restofline void $ string indent1 lambdaprefix <- string "(\\ " l1 <- restofline void $ string indent1 lambdaarrow <- string " ->" l2 <- restofline l3 <- if '{' `elem` l2 && '}' `elem` l2 then return "" else do void $ string indent1 restofline return $ unlines [ indent1 ++ staticr , indent1 ++ yesod_dispatch_env , indent1 ++ "(" ++ lambdaprefix ++ l1 , indent1 ++ lambdaarrow ++ l2 ++ l3 ++ ")" ] restofline = manyTill (noneOf "\n") newline {- For some reason, GHC sometimes doesn't like the multiline - strings it creates. It seems to get hung up on \{ at the - start of a new line sometimes, wanting it to not be escaped. - - To work around what is likely a GHC bug, just collapse - multiline strings. -} collapse_multiline_strings = parsecAndReplace $ do void $ string "\\\n" void $ many1 $ oneOf " \t" void $ string "\\" return "\\n" {- GHC outputs splices using explicit braces rather than layout. - For a case expression, it does something weird: - - case foo of { - xxx -> blah - yyy -> blah }; - - This is not legal Haskell; the statements in the case must be - separated by ';' - - To fix, we could just put a semicolon at the start of every line - containing " -> " ... Except that lambdas also contain that. - But we can get around that: GHC outputs lambas like this: - - \ foo - -> bar - - Or like this: - - \ foo -> bar - - So, we can put the semicolon at the start of every line - containing " -> " unless there's a "\ " first, or it's - all whitespace up until it. -} case_layout = parsecAndReplace $ do void newline indent1 <- many1 $ char ' ' prefix <- manyTill (noneOf "\n") (try (string "-> ")) if length prefix > 10 then unexpected "too long a prefix" else if "\\ " `isInfixOf` prefix then unexpected "lambda expression" else if null prefix then unexpected "second line of lambda" else return $ "\n" ++ indent1 ++ "; " ++ prefix ++ " -> " {- Sometimes cases themselves span multiple lines: - - Nothing - -> foo - - -- This is not yet handled! - ComplexConstructor var var - var var - -> foo -} case_layout_multiline = parsecAndReplace $ do void newline indent1 <- many1 $ char ' ' firstline <- restofline void $ string indent1 indent2 <- many1 $ char ' ' void $ string "-> " if "\\ " `isInfixOf` firstline then unexpected "lambda expression" else return $ "\n" ++ indent1 ++ "; " ++ firstline ++ "\n" ++ indent1 ++ indent2 ++ "-> " {- (foo, \ -> bar) is not valid haskell, GHC. - Change to (foo, bar) - - (Does this ever happen outside a tuple? Only saw - it inside them.. -} emptylambda = replace ", \\ -> " ", " {- GHC may output this: - - instance RenderRoute WebApp where - data instance Route WebApp - ^^^^^^^^ - The marked word should not be there. - - FIXME: This is a yesod-specific hack, it should look for the - outer instance. -} nested_instances = replace " data instance Route" " data Route" {- GHC does not properly parenthesise generated data type - declarations. -} declaration_parens = replace "StaticR Route Static" "StaticR (Route Static)" {- A type signature is sometimes given for an entire lambda, - which is not properly parenthesized or laid out. This is a - hack to remove one specific case where this happens and the - signature is easily inferred, so is just removed. -} remove_unnecessary_type_signatures = parsecAndReplace $ do void $ string " ::" void newline void $ many1 $ char ' ' void $ string "Text.Css.Block Text.Css.Resolved" void newline return "" {- GHC may add full package and version qualifications for - symbols from unimported modules. We don't want these. - - Examples: - "blaze-html-0.4.3.1:Text.Blaze.Internal.preEscapedText" - "ghc-prim:GHC.Types.:" -} remove_package_version = parsecAndReplace $ mangleSymbol <$> qualifiedSymbol mangleSymbol "GHC.Types." = "" mangleSymbol "GHC.Tuple." = "" mangleSymbol s = s qualifiedSymbol :: Parser String qualifiedSymbol = do s <- hstoken void $ char ':' if length s < 5 then unexpected "too short to be a namespace" else do t <- hstoken case t of (c:r) | isUpper c && "." `isInfixOf` r -> return t _ -> unexpected "not a module qualified symbol" hstoken :: Parser String hstoken = do t <- satisfy isLetter oken <- many $ satisfy isAlphaNum <|> oneOf "-.'" return $ t:oken {- This works when it's "GHC.Types.:", but we strip - that above, so have to fix up after it here. - The ; is added by case_layout. -} flip_colon = replace "; : _ " "; _ : " {- Embedded files use unsafe packing, which is problimatic - for several reasons, including that GHC sometimes omits trailing - newlines in the file content, which leads to the wrong byte - count. Also, GHC sometimes outputs unicode characters, which - are not legal in unboxed strings. - - Avoid problems by converting: - GHC.IO.unsafePerformIO - (Data.ByteString.Unsafe.unsafePackAddressLen - lllll - "blabblah"#)), - to: - Data.ByteString.Char8.pack "blabblah"), - - Note that the string is often multiline. This only works if - collapse_multiline_strings has run first. -} boxed_fileembed :: String -> String boxed_fileembed = parsecAndReplace $ do i <- indent void $ string "GHC.IO.unsafePerformIO" void newline void indent void $ string "(Data.ByteString.Unsafe.unsafePackAddressLen" void newline void indent void number void newline void indent void $ char '"' s <- restOfLine let s' = take (length s - 5) s if "\"#))," `isSuffixOf` s then return (i ++ "Data.ByteString.Char8.pack \"" ++ s' ++ "\"),\n") else fail "not an unboxed string" {- This works around a problem in the expanded template haskell for Yesod - type-safe url rendering. - - It generates code like this: - - (toHtml - (\ u_a2ehE -> urender_a2ehD u_a2ehE [] - (CloseAlert aid))))); - - Where urender_a2ehD is the function returned by getUrlRenderParams. - But, that function that only takes 2 params, not 3. - And toHtml doesn't take a parameter at all! - - So, this modifes the code, to look like this: - - (toHtml - (flip urender_a2ehD [] - (CloseAlert aid))))); - - FIXME: Investigate and fix this properly. -} yesod_url_render_hack :: String -> String yesod_url_render_hack = parsecAndReplace $ do void $ string "(toHtml" void whitespace void $ string "(\\" void whitespace wtf <- hstoken void whitespace void $ string "->" void whitespace renderer <- hstoken void whitespace void $ string wtf void whitespace return $ "(toHtml (flip " ++ renderer ++ " " where whitespace :: Parser String whitespace = many $ oneOf " \t\r\n" hstoken :: Parser String hstoken = many1 $ satisfy isAlphaNum <|> oneOf "_" {- Use exported symbol. -} text_builder_hack :: String -> String text_builder_hack = replace "Data.Text.Lazy.Builder.Internal.fromText" "Data.Text.Lazy.Builder.fromText" {- Given a Parser that finds strings it wants to modify, - and returns the modified string, does a mass - find and replace throughout the input string. - Rather slow, but crazy powerful. -} parsecAndReplace :: Parser String -> String -> String parsecAndReplace p s = case parse find "" s of Left _e -> s Right l -> concatMap (either return id) l where find :: Parser [Either Char String] find = many $ try (Right <$> p) <|> (Left <$> anyChar) main :: IO () main = go =<< getArgs where go (destdir:log:header:[]) = run destdir log (Just header) go (destdir:log:[]) = run destdir log Nothing go _ = error "usage: EvilSplicer destdir logfile [headerfile]" run destdir log mheader = do r <- parseFromFile splicesExtractor log case r of Left e -> error $ show e Right splices -> do let groups = groupBy (\a b -> splicedFile a == splicedFile b) splices imports <- maybe (return Nothing) (catchMaybeIO . readFile) mheader mapM_ (applySplices destdir imports) groups