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