{-# OPTIONS -cpp #-}

------------------------------------------------------------------------
-- Program for converting .hsc files to .hs files, by converting the
-- file into a C program which is run to generate the Haskell source.
-- Certain items known only to the C compiler can then be used in
-- the Haskell module; for example #defined constants, byte offsets
-- within structures, etc.
--
-- See the documentation in the Users' Guide for more details.

import Control.Monad		( MonadPlus(..), liftM, liftM2, when )
import Data.Char		( isAlpha, isAlphaNum, isSpace, isDigit,
				  toUpper, intToDigit, ord )
import Data.List		( intersperse, isSuffixOf )
import System.Cmd		( system, rawSystem )
import System.Console.GetOpt
import System.Directory		( removeFile, doesFileExist )
import System.Environment	( getProgName, getArgs )
import System.Exit		( ExitCode(..), exitWith )
import System.IO		( hPutStr, hPutStrLn, stderr )

#if __GLASGOW_HASKELL__ >= 604 || defined(__NHC__) || defined(__HUGS__)
import System.Directory		( findExecutable )
#else
import System.Directory		( getPermissions, executable )
import System.Environment	( getEnv )
import Control.Monad		( foldM )
#endif

#if __GLASGOW_HASKELL__ >= 604
import System.Process           ( runProcess, waitForProcess )
import System.IO                ( openFile, IOMode(..), hClose )
#define HAVE_runProcess
#endif

#if ! BUILD_NHC
import Paths_hsc2hs		( getDataFileName, version )
import Data.Version		( showVersion )
#else
import System.Directory		( getCurrentDirectory )
getDataFileName s = do here <- getCurrentDirectory
                       return (here++"/"++s)
version = "0.67" -- TODO!!!
showVersion = id
#endif

#ifdef __GLASGOW_HASKELL__
default_compiler = "ghc"
#else
default_compiler = "gcc"
#endif

#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 604)
findExecutable :: String -> IO (Maybe FilePath)
findExecutable cmd =
  let dir = dirname cmd
  in case dir of
    "" -> do -- search the shell environment PATH variable for candidates
             val <- getEnv "PATH"
             let psep = pathSep val
                 dirs = splitPath psep "" val
             foldM (\a dir-> testFile a (dir++'/':cmd)) Nothing dirs
    _  -> do testFile Nothing cmd
  where
    splitPath :: Char -> String -> String -> [String]
    splitPath sep acc []                 = [reverse acc]
    splitPath sep acc (c:path) | c==sep  = reverse acc : splitPath sep "" path
    splitPath sep acc (c:path)           = splitPath sep (c:acc) path

    pathSep s = if length (filter (==';') s) >0 then ';' else ':'

    testFile :: Maybe String -> String -> IO (Maybe String)
    testFile gotit@(Just _) path = return gotit
    testFile Nothing path = do
        ok <- doesFileExist path
        if ok then perms path else return Nothing

    perms file = do
        p <- getPermissions file
        return (if executable p then Just file else Nothing)

    dirname  = reverse . safetail . dropWhile (not.(`elem`"\\/")) . reverse
      where safetail [] = []
            safetail (_:x) = x
#endif

versionString :: String
versionString = "hsc2hs version " ++ showVersion version ++ "\n"

data Flag
    = Help
    | Version
    | Template  String
    | Compiler  String
    | Linker    String
    | CompFlag  String
    | LinkFlag  String
    | NoCompile
    | Include   String
    | Define    String (Maybe String)
    | Output    String
    | Verbose

template_flag :: Flag -> Bool
template_flag (Template _) = True
template_flag _		   = False

include :: String -> Flag
include s@('\"':_) = Include s
include s@('<' :_) = Include s
include s          = Include ("\""++s++"\"")

define :: String -> Flag
define s = case break (== '=') s of
    (name, [])      -> Define name Nothing
    (name, _:value) -> Define name (Just value)

options :: [OptDescr Flag]
options = [
    Option ['o'] ["output"]     (ReqArg Output     "FILE")
        "name of main output file",
    Option ['t'] ["template"]   (ReqArg Template   "FILE")
        "template file",
    Option ['c'] ["cc"]         (ReqArg Compiler   "PROG")
        "C compiler to use",
    Option ['l'] ["ld"]         (ReqArg Linker     "PROG")
        "linker to use",
    Option ['C'] ["cflag"]      (ReqArg CompFlag   "FLAG")
        "flag to pass to the C compiler",
    Option ['I'] []             (ReqArg (CompFlag . ("-I"++)) "DIR")
        "passed to the C compiler",
    Option ['L'] ["lflag"]      (ReqArg LinkFlag   "FLAG")
        "flag to pass to the linker",
    Option ['i'] ["include"]    (ReqArg include    "FILE")
        "as if placed in the source",
    Option ['D'] ["define"]     (ReqArg define "NAME[=VALUE]")
        "as if placed in the source",
    Option []    ["no-compile"] (NoArg  NoCompile)
        "stop after writing *_hsc_make.c",
    Option ['v'] ["verbose"]    (NoArg  Verbose)
        "dump commands to stderr",
    Option ['?'] ["help"]       (NoArg  Help)
        "display this help and exit",
    Option ['V'] ["version"]    (NoArg  Version)
        "output version information and exit" ]

main :: IO ()
main = do
    prog <- getProgramName
    let header = "Usage: "++prog++" [OPTIONS] INPUT.hsc [...]\n"
    args <- getArgs
    let (flags, files, errs) = getOpt Permute options args

	-- If there is no Template flag explicitly specified,
	-- use the file placed by the Cabal installation.
    flags_w_tpl <-
	if any template_flag flags then
	    return flags
	  else do
	    templ <- getDataFileName "template-hsc.h"
	    return (Template templ : flags)
    case (files, errs) of
        (_, _)
            | any isHelp    flags_w_tpl -> bye (usageInfo header options)
            | any isVersion flags_w_tpl -> bye versionString
            where
            isHelp    Help    = True; isHelp    _ = False
            isVersion Version = True; isVersion _ = False
        ((_:_), []) -> mapM_ (processFile flags_w_tpl) files
        (_,     _ ) -> die (concat errs ++ usageInfo header options)

getProgramName :: IO String
getProgramName = liftM (`withoutSuffix` "-bin") getProgName
   where str `withoutSuffix` suff
            | suff `isSuffixOf` str = take (length str - length suff) str
            | otherwise             = str

bye :: String -> IO a
bye s = putStr s >> exitWith ExitSuccess

die :: String -> IO a
die s = hPutStr stderr s >> exitWith (ExitFailure 1)

processFile :: [Flag] -> String -> IO ()
processFile flags name
  = do let file_name = dosifyPath name
       s <- readFile file_name
       case parser of
    	   Parser p -> case p (SourcePos file_name 1) s of
    	       Success _ _ _ toks -> output flags file_name toks
    	       Failure (SourcePos name' line) msg ->
    		   die (name'++":"++show line++": "++msg++"\n")

------------------------------------------------------------------------
-- A deterministic parser which remembers the text which has been parsed.

newtype Parser a = Parser (SourcePos -> String -> ParseResult a)

data ParseResult a = Success !SourcePos String String a
                   | Failure !SourcePos String

data SourcePos = SourcePos String !Int

updatePos :: SourcePos -> Char -> SourcePos
updatePos pos@(SourcePos name line) ch = case ch of
    '\n' -> SourcePos name (line + 1)
    _    -> pos

instance Monad Parser where
    return a = Parser $ \pos s -> Success pos [] s a
    Parser m >>= k =
        Parser $ \pos s -> case m pos s of
            Success pos' out1 s' a -> case k a of
                Parser k' -> case k' pos' s' of
                    Success pos'' out2 imp'' b ->
                        Success pos'' (out1++out2) imp'' b
                    Failure pos'' msg -> Failure pos'' msg
            Failure pos' msg -> Failure pos' msg
    fail msg = Parser $ \pos _ -> Failure pos msg

instance MonadPlus Parser where
    mzero                     = fail "mzero"
    Parser m `mplus` Parser n =
        Parser $ \pos s -> case m pos s of
            success@(Success _ _ _ _) -> success
            Failure _ _               -> n pos s

getPos :: Parser SourcePos
getPos = Parser $ \pos s -> Success pos [] s pos

setPos :: SourcePos -> Parser ()
setPos pos = Parser $ \_ s -> Success pos [] s ()

message :: Parser a -> String -> Parser a
Parser m `message` msg =
    Parser $ \pos s -> case m pos s of
        success@(Success _ _ _ _) -> success
        Failure pos' _            -> Failure pos' msg

catchOutput_ :: Parser a -> Parser String
catchOutput_ (Parser m) =
    Parser $ \pos s -> case m pos s of
        Success pos' out s' _ -> Success pos' [] s' out
        Failure pos' msg      -> Failure pos' msg

fakeOutput :: Parser a -> String -> Parser a
Parser m `fakeOutput` out =
    Parser $ \pos s -> case m pos s of
        Success pos' _ s' a -> Success pos' out s' a
        Failure pos' msg    -> Failure pos' msg

lookAhead :: Parser String
lookAhead = Parser $ \pos s -> Success pos [] s s

satisfy :: (Char -> Bool) -> Parser Char
satisfy p =
    Parser $ \pos s -> case s of
        c:cs | p c -> Success (updatePos pos c) [c] cs c
        _          -> Failure pos "Bad character"

char_ :: Char -> Parser ()
char_ c = do
    satisfy (== c) `message` (show c++" expected")
    return ()

anyChar_ :: Parser ()
anyChar_ = do
    satisfy (const True) `message` "Unexpected end of file"
    return ()

any2Chars_ :: Parser ()
any2Chars_ = anyChar_ >> anyChar_

many :: Parser a -> Parser [a]
many p = many1 p `mplus` return []

many1 :: Parser a -> Parser [a]
many1 p = liftM2 (:) p (many p)

many_ :: Parser a -> Parser ()
many_ p = many1_ p `mplus` return ()

many1_ :: Parser a -> Parser ()
many1_ p = p >> many_ p

manySatisfy, manySatisfy1 :: (Char -> Bool) -> Parser String
manySatisfy  = many  . satisfy
manySatisfy1 = many1 . satisfy

manySatisfy_, manySatisfy1_ :: (Char -> Bool) -> Parser ()
manySatisfy_  = many_  . satisfy
manySatisfy1_ = many1_ . satisfy

------------------------------------------------------------------------
-- Parser of hsc syntax.

data Token
    = Text    SourcePos String
    | Special SourcePos String String

parser :: Parser [Token]
parser = do
    pos <- getPos
    t <- catchOutput_ text
    s <- lookAhead
    rest <- case s of
        []  -> return []
        _:_ -> liftM2 (:) (special `fakeOutput` []) parser
    return (if null t then rest else Text pos t : rest)

text :: Parser ()
text = do
    s <- lookAhead
    case s of
        []        -> return ()
        c:_ | isAlpha c || c == '_' -> do
            anyChar_
            manySatisfy_ (\c' -> isAlphaNum c' || c' == '_' || c' == '\'')
            text
        c:_ | isHsSymbol c -> do
            symb <- catchOutput_ (manySatisfy_ isHsSymbol)
            case symb of
                "#" -> return ()
                '-':'-':symb' | all (== '-') symb' -> do
                    return () `fakeOutput` symb
                    manySatisfy_ (/= '\n')
                    text
                _ -> do
                    return () `fakeOutput` unescapeHashes symb
                    text
        '\"':_    -> do anyChar_; hsString '\"'; text
        '\'':_    -> do anyChar_; hsString '\''; text
        '{':'-':_ -> do any2Chars_; linePragma `mplus` hsComment; text
        _:_       -> do anyChar_; text

hsString :: Char -> Parser ()
hsString quote = do
    s <- lookAhead
    case s of
        []               -> return ()
        c:_ | c == quote -> anyChar_
        '\\':c:_
            | isSpace c  -> do
                anyChar_
                manySatisfy_ isSpace
                char_ '\\' `mplus` return ()
                hsString quote
            | otherwise  -> do any2Chars_; hsString quote
        _:_              -> do anyChar_; hsString quote

hsComment :: Parser ()
hsComment = do
    s <- lookAhead
    case s of
        []        -> return ()
        '-':'}':_ -> any2Chars_
        '{':'-':_ -> do any2Chars_; hsComment; hsComment
        _:_       -> do anyChar_; hsComment

linePragma :: Parser ()
linePragma = do
    char_ '#'
    manySatisfy_ isSpace
    satisfy (\c -> c == 'L' || c == 'l')
    satisfy (\c -> c == 'I' || c == 'i')
    satisfy (\c -> c == 'N' || c == 'n')
    satisfy (\c -> c == 'E' || c == 'e')
    manySatisfy1_ isSpace
    line <- liftM read $ manySatisfy1 isDigit
    manySatisfy1_ isSpace
    char_ '\"'
    name <- manySatisfy (/= '\"')
    char_ '\"'
    manySatisfy_ isSpace
    char_ '#'
    char_ '-'
    char_ '}'
    setPos (SourcePos name (line - 1))

isHsSymbol :: Char -> Bool
isHsSymbol '!' = True; isHsSymbol '#' = True; isHsSymbol '$'  = True
isHsSymbol '%' = True; isHsSymbol '&' = True; isHsSymbol '*'  = True
isHsSymbol '+' = True; isHsSymbol '.' = True; isHsSymbol '/'  = True
isHsSymbol '<' = True; isHsSymbol '=' = True; isHsSymbol '>'  = True
isHsSymbol '?' = True; isHsSymbol '@' = True; isHsSymbol '\\' = True
isHsSymbol '^' = True; isHsSymbol '|' = True; isHsSymbol '-'  = True
isHsSymbol '~' = True
isHsSymbol _   = False

unescapeHashes :: String -> String
unescapeHashes []          = []
unescapeHashes ('#':'#':s) = '#' : unescapeHashes s
unescapeHashes (c:s)       = c   : unescapeHashes s

lookAheadC :: Parser String
lookAheadC = liftM joinLines lookAhead
    where
    joinLines []            = []
    joinLines ('\\':'\n':s) = joinLines s
    joinLines (c:s)         = c : joinLines s

satisfyC :: (Char -> Bool) -> Parser Char
satisfyC p = do
    s <- lookAhead
    case s of
        '\\':'\n':_ -> do any2Chars_ `fakeOutput` []; satisfyC p
        _           -> satisfy p

charC_ :: Char -> Parser ()
charC_ c = do
    satisfyC (== c) `message` (show c++" expected")
    return ()

anyCharC_ :: Parser ()
anyCharC_ = do
    satisfyC (const True) `message` "Unexpected end of file"
    return ()

any2CharsC_ :: Parser ()
any2CharsC_ = anyCharC_ >> anyCharC_

manySatisfyC :: (Char -> Bool) -> Parser String
manySatisfyC = many . satisfyC

manySatisfyC_ :: (Char -> Bool) -> Parser ()
manySatisfyC_ = many_ . satisfyC

special :: Parser Token
special = do
    manySatisfyC_ (\c -> isSpace c && c /= '\n')
    s <- lookAheadC
    case s of
        '{':_ -> do
            anyCharC_
            manySatisfyC_ isSpace
            sp <- keyArg (== '\n')
            charC_ '}'
            return sp
        _ -> keyArg (const False)

keyArg :: (Char -> Bool) -> Parser Token
keyArg eol = do
    pos <- getPos
    key <- keyword `message` "hsc keyword or '{' expected"
    manySatisfyC_ (\c' -> isSpace c' && c' /= '\n' || eol c')
    arg <- catchOutput_ (argument eol)
    return (Special pos key arg)

keyword :: Parser String
keyword = do
    c  <- satisfyC (\c' -> isAlpha c' || c' == '_')
    cs <- manySatisfyC (\c' -> isAlphaNum c' || c' == '_')
    return (c:cs)

argument :: (Char -> Bool) -> Parser ()
argument eol = do
    s <- lookAheadC
    case s of
        []          -> return ()
        c:_ | eol c -> do anyCharC_;               argument eol
        '\n':_      -> return ()
        '\"':_      -> do anyCharC_; cString '\"'; argument eol
        '\'':_      -> do anyCharC_; cString '\''; argument eol
        '(':_       -> do anyCharC_; nested ')';   argument eol
        ')':_       -> return ()
        '/':'*':_   -> do any2CharsC_; cComment;   argument eol
        '/':'/':_   -> do
            any2CharsC_; manySatisfyC_ (/= '\n');  argument eol
        '[':_       -> do anyCharC_; nested ']';   argument eol
        ']':_       -> return ()
        '{':_       -> do anyCharC_; nested '}';   argument eol
        '}':_       -> return ()
        _:_         -> do anyCharC_;               argument eol

nested :: Char -> Parser ()
nested c = do argument (== '\n'); charC_ c

cComment :: Parser ()
cComment = do
    s <- lookAheadC
    case s of
        []        -> return ()
        '*':'/':_ -> do any2CharsC_
        _:_       -> do anyCharC_; cComment

cString :: Char -> Parser ()
cString quote = do
    s <- lookAheadC
    case s of
        []               -> return ()
        c:_ | c == quote -> anyCharC_
        '\\':_:_         -> do any2CharsC_; cString quote
        _:_              -> do anyCharC_; cString quote

------------------------------------------------------------------------
-- Write the output files.

splitName :: String -> (String, String)
splitName name =
    case break (== '/') name of
        (file, [])       -> ([], file)
        (dir,  sep:rest) -> (dir++sep:restDir, restFile)
            where
            (restDir, restFile) = splitName rest

splitExt :: String -> (String, String)
splitExt name =
    case break (== '.') name of
        (base, [])         -> (base, [])
        (base, sepRest@(sep:rest))
            | null restExt -> (base,               sepRest)
            | otherwise    -> (base++sep:restBase, restExt)
            where
            (restBase, restExt) = splitExt rest

output :: [Flag] -> String -> [Token] -> IO ()
output flags name toks = do

    (outName, outDir, outBase) <- case [f | Output f <- flags] of
        [] -> if not (null ext) && last ext == 'c'
                 then return (dir++base++init ext,  dir, base)
                 else
                    if ext == ".hs"
                       then return (dir++base++"_out.hs", dir, base)
                       else return (dir++base++".hs",     dir, base)
              where
               (dir,  file) = splitName name
               (base, ext)  = splitExt  file
        [f] -> let
            (dir,  file) = splitName f
            (base, _)    = splitExt file
            in return (f, dir, base)
        _ -> onlyOne "output file"

    let cProgName    = outDir++outBase++"_hsc_make.c"
        oProgName    = outDir++outBase++"_hsc_make.o"
        progName     = outDir++outBase++"_hsc_make"
#if defined(mingw32_HOST_OS) || defined(__CYGWIN32__)
-- This is a real hack, but the quoting mechanism used for calling the C preprocesseor
-- via GHC has changed a few times, so this seems to be the only way...  :-P * * *
                          ++ ".exe"
#endif
	outHFile     = outBase++"_hsc.h"
        outHName     = outDir++outHFile
        outCName     = outDir++outBase++"_hsc.c"

	beVerbose    = any (\ x -> case x of { Verbose -> True; _ -> False}) flags

    let execProgName
            | null outDir = dosifyPath ("./" ++ progName)
            | otherwise   = progName

    let specials = [(pos, key, arg) | Special pos key arg <- toks]

    let needsC = any (\(_, key, _) -> key == "def") specials
        needsH = needsC

    let includeGuard = map fixChar outHName
            where
            fixChar c | isAlphaNum c = toUpper c
                      | otherwise    = '_'

    compiler <- case [c | Compiler c <- flags] of
        []  -> do
	    mb_path <- findExecutable default_compiler
	    case mb_path of
		Nothing -> die ("Can't find "++default_compiler++"\n")
		Just path -> return path
        [c] -> return c
        _   -> onlyOne "compiler"

    linker <- case [l | Linker l <- flags] of
        []  -> return compiler
        [l] -> return l
        _   -> onlyOne "linker"

    writeFile cProgName $
        concatMap outFlagHeaderCProg flags++
        concatMap outHeaderCProg specials++
        "\nint main (int argc, char *argv [])\n{\n"++
        outHeaderHs flags (if needsH then Just outHName else Nothing) specials++
        outHsLine (SourcePos name 0)++
        concatMap outTokenHs toks++
        "    return 0;\n}\n"

    -- NOTE: hbc compiles "[() | NoCompile <- flags]" into wrong code,
    -- so we use something slightly more complicated.   :-P
    when (any (\x -> case x of NoCompile -> True; _ -> False) flags) $
       exitWith ExitSuccess

    rawSystemL ("compiling " ++ cProgName) beVerbose compiler
	(  ["-c"]
        ++ [f | CompFlag f <- flags]
        ++ [cProgName]
        ++ ["-o", oProgName]
	)
    removeFile cProgName

    rawSystemL ("linking " ++ oProgName) beVerbose linker
        (  [f | LinkFlag f <- flags]
        ++ [oProgName]
        ++ ["-o", progName]
	)
    removeFile oProgName

    rawSystemWithStdOutL ("running " ++ execProgName) beVerbose execProgName [] outName
    removeFile progName

    when needsH $ writeFile outHName $
        "#ifndef "++includeGuard++"\n" ++
        "#define "++includeGuard++"\n" ++
        "#if __GLASGOW_HASKELL__ && __GLASGOW_HASKELL__ < 409\n" ++
        "#include <Rts.h>\n" ++
        "#endif\n" ++
        "#include <HsFFI.h>\n" ++
        "#if __NHC__\n" ++
        "#undef HsChar\n" ++
        "#define HsChar int\n" ++
        "#endif\n" ++
        concatMap outFlagH flags++
        concatMap outTokenH specials++
        "#endif\n"

    when needsC $ writeFile outCName $
        "#include \""++outHFile++"\"\n"++
        concatMap outTokenC specials
	-- NB. outHFile not outHName; works better when processed
	-- by gcc or mkdependC.

rawSystemL :: String -> Bool -> FilePath -> [String] -> IO ()
rawSystemL action flg prog args = do
  let cmdLine = prog++" "++unwords args
  when flg $ hPutStrLn stderr ("Executing: " ++ cmdLine)
#ifndef HAVE_rawSystem
  exitStatus <- system cmdLine
#else
  exitStatus <- rawSystem prog args
#endif
  case exitStatus of
    ExitFailure _ -> die $ action ++ " failed\ncommand was: " ++ cmdLine ++ "\n"
    _             -> return ()

rawSystemWithStdOutL :: String -> Bool -> FilePath -> [String] -> FilePath -> IO ()
rawSystemWithStdOutL action flg prog args outFile = do
  let cmdLine = prog++" "++unwords args++" >"++outFile
  when flg (hPutStrLn stderr ("Executing: " ++ cmdLine))
#ifndef HAVE_runProcess
  exitStatus <- system cmdLine
#else
  hOut <- openFile outFile WriteMode
  process <- runProcess prog args Nothing Nothing Nothing (Just hOut) Nothing
  exitStatus <- waitForProcess process
  hClose hOut
#endif
  case exitStatus of
    ExitFailure _ -> die $ action ++ " failed\ncommand was: " ++ cmdLine ++ "\n"
    _             -> return ()

onlyOne :: String -> IO a
onlyOne what = die ("Only one "++what++" may be specified\n")

outFlagHeaderCProg :: Flag -> String
outFlagHeaderCProg (Template t)          = "#include \""++t++"\"\n"
outFlagHeaderCProg (Include  f)          = "#include "++f++"\n"
outFlagHeaderCProg (Define   n Nothing)  = "#define "++n++" 1\n"
outFlagHeaderCProg (Define   n (Just v)) = "#define "++n++" "++v++"\n"
outFlagHeaderCProg _                     = ""

outHeaderCProg :: (SourcePos, String, String) -> String
outHeaderCProg (pos, key, arg) = case key of
    "include"           -> outCLine pos++"#include "++arg++"\n"
    "define"            -> outCLine pos++"#define "++arg++"\n"
    "undef"             -> outCLine pos++"#undef "++arg++"\n"
    "def"               -> case arg of
        's':'t':'r':'u':'c':'t':' ':_ -> outCLine pos++arg++"\n"
        't':'y':'p':'e':'d':'e':'f':' ':_ -> outCLine pos++arg++"\n"
        _ -> ""
    _ | conditional key -> outCLine pos++"#"++key++" "++arg++"\n"
    "let"               -> case break (== '=') arg of
        (_,      "")     -> ""
        (header, _:body) -> case break isSpace header of
            (name, args) ->
                outCLine pos++
                "#define hsc_"++name++"("++dropWhile isSpace args++") " ++
                "printf ("++joinLines body++");\n"
    _ -> ""
   where
    joinLines = concat . intersperse " \\\n" . lines

outHeaderHs :: [Flag] -> Maybe String -> [(SourcePos, String, String)] -> String
outHeaderHs flags inH toks =
    "#if " ++
    "__GLASGOW_HASKELL__ && __GLASGOW_HASKELL__ < 409\n" ++
    "    printf (\"{-# OPTIONS -optc-D" ++
    "__GLASGOW_HASKELL__=%d #-}\\n\", " ++
    "__GLASGOW_HASKELL__);\n" ++
    "#endif\n"++
    case inH of
        Nothing -> concatMap outFlag flags++concatMap outSpecial toks
        Just f  -> outInclude ("\""++f++"\"")
    where
    outFlag (Include f)          = outInclude f
    outFlag (Define  n Nothing)  = outOption ("-optc-D"++n)
    outFlag (Define  n (Just v)) = outOption ("-optc-D"++n++"="++v)
    outFlag _                    = ""
    outSpecial (pos, key, arg) = case key of
        "include"                  -> outInclude arg
        "define" | goodForOptD arg -> outOption ("-optc-D"++toOptD arg)
                 | otherwise       -> ""
        _ | conditional key        -> outCLine pos++"#"++key++" "++arg++"\n"
        _                          -> ""
    goodForOptD arg = case arg of
        ""              -> True
        c:_ | isSpace c -> True
        '(':_           -> False
        _:s             -> goodForOptD s
    toOptD arg = case break isSpace arg of
        (name, "")      -> name
        (name, _:value) -> name++'=':dropWhile isSpace value
    outOption s =
	"#if __GLASGOW_HASKELL__ && __GLASGOW_HASKELL__ < 603\n" ++
	"    printf (\"{-# OPTIONS %s #-}\\n\", \""++
                  showCString s++"\");\n"++
	"#else\n"++
	"    printf (\"{-# OPTIONS_GHC %s #-}\\n\", \""++
                  showCString s++"\");\n"++
	"#endif\n"
    outInclude s =
	"#if __GLASGOW_HASKELL__ && __GLASGOW_HASKELL__ < 603\n" ++
	"    printf (\"{-# OPTIONS -#include %s #-}\\n\", \""++
                  showCString s++"\");\n"++
	"#else\n"++
	"    printf (\"{-# INCLUDE %s #-}\\n\", \""++
                  showCString s++"\");\n"++
	"#endif\n"

outTokenHs :: Token -> String
outTokenHs (Text pos txt) =
    case break (== '\n') txt of
        (allTxt, [])       -> outText allTxt
        (first, _:rest) ->
            outText (first++"\n")++
            outHsLine pos++
            outText rest
    where
    outText s = "    fputs (\""++showCString s++"\", stdout);\n"
outTokenHs (Special pos key arg) =
    case key of
        "include"           -> ""
        "define"            -> ""
        "undef"             -> ""
        "def"               -> ""
        _ | conditional key -> outCLine pos++"#"++key++" "++arg++"\n"
        "let"               -> ""
        "enum"              -> outCLine pos++outEnum arg
        _                   -> outCLine pos++"    hsc_"++key++" ("++arg++");\n"

outEnum :: String -> String
outEnum arg =
    case break (== ',') arg of
        (_, [])        -> ""
        (t, _:afterT) -> case break (== ',') afterT of
            (f, afterF) -> let
                enums []    = ""
                enums (_:s) = case break (== ',') s of
                    (enum, rest) -> let
                        this = case break (== '=') $ dropWhile isSpace enum of
                            (name, []) ->
                                "    hsc_enum ("++t++", "++f++", " ++
                                "hsc_haskellize (\""++name++"\"), "++
                                name++");\n"
                            (hsName, _:cName) ->
                                "    hsc_enum ("++t++", "++f++", " ++
                                "printf (\"%s\", \""++hsName++"\"), "++
                                cName++");\n"
                        in this++enums rest
                in enums afterF

outFlagH :: Flag -> String
outFlagH (Include  f)          = "#include "++f++"\n"
outFlagH (Define   n Nothing)  = "#define "++n++" 1\n"
outFlagH (Define   n (Just v)) = "#define "++n++" "++v++"\n"
outFlagH _                     = ""

outTokenH :: (SourcePos, String, String) -> String
outTokenH (pos, key, arg) =
    case key of
        "include" -> outCLine pos++"#include "++arg++"\n"
        "define"  -> outCLine pos++"#define " ++arg++"\n"
        "undef"   -> outCLine pos++"#undef "  ++arg++"\n"
        "def"     -> outCLine pos++case arg of
            's':'t':'r':'u':'c':'t':' ':_ -> arg++"\n"
            't':'y':'p':'e':'d':'e':'f':' ':_ -> arg++"\n"
            'i':'n':'l':'i':'n':'e':' ':_ ->
                "#ifdef __GNUC__\n" ++
                "extern\n" ++
                "#endif\n"++
                arg++"\n"
            _ -> "extern "++header++";\n"
          where header = takeWhile (\c -> c /= '{' && c /= '=') arg
        _ | conditional key -> outCLine pos++"#"++key++" "++arg++"\n"
        _ -> ""

outTokenC :: (SourcePos, String, String) -> String
outTokenC (pos, key, arg) =
    case key of
        "def" -> case arg of
            's':'t':'r':'u':'c':'t':' ':_ -> ""
            't':'y':'p':'e':'d':'e':'f':' ':_ -> ""
            'i':'n':'l':'i':'n':'e':' ':arg' ->
		case span (\c -> c /= '{' && c /= '=') arg' of
		(header, body) ->
		    outCLine pos++
		    "#ifndef __GNUC__\n" ++
		    "extern inline\n" ++
		    "#endif\n"++
		    header++
		    "\n#ifndef __GNUC__\n" ++
		    ";\n" ++
		    "#else\n"++
		    body++
		    "\n#endif\n"
            _ -> outCLine pos++arg++"\n"
        _ | conditional key -> outCLine pos++"#"++key++" "++arg++"\n"
        _ -> ""

conditional :: String -> Bool
conditional "if"      = True
conditional "ifdef"   = True
conditional "ifndef"  = True
conditional "elif"    = True
conditional "else"    = True
conditional "endif"   = True
conditional "error"   = True
conditional "warning" = True
conditional _         = False

outCLine :: SourcePos -> String
outCLine (SourcePos name line) =
    "#line "++show line++" \""++showCString (snd (splitName name))++"\"\n"

outHsLine :: SourcePos -> String
outHsLine (SourcePos name line) =
    "    hsc_line ("++show (line + 1)++", \""++
    showCString name++"\");\n"

showCString :: String -> String
showCString = concatMap showCChar
    where
    showCChar '\"' = "\\\""
    showCChar '\'' = "\\\'"
    showCChar '?'  = "\\?"
    showCChar '\\' = "\\\\"
    showCChar c | c >= ' ' && c <= '~' = [c]
    showCChar '\a' = "\\a"
    showCChar '\b' = "\\b"
    showCChar '\f' = "\\f"
    showCChar '\n' = "\\n\"\n           \""
    showCChar '\r' = "\\r"
    showCChar '\t' = "\\t"
    showCChar '\v' = "\\v"
    showCChar c    = ['\\',
                      intToDigit (ord c `quot` 64),
                      intToDigit (ord c `quot` 8 `mod` 8),
                      intToDigit (ord c          `mod` 8)]

-----------------------------------------
-- Modified version from ghc/compiler/SysTools
-- Convert paths foo/baz to foo\baz on Windows

subst :: Char -> Char -> String -> String
#if defined(mingw32_HOST_OS) || defined(__CYGWIN32__)
subst a b = map (\x -> if x == a then b else x)
#else
subst _ _ = id
#endif

dosifyPath :: String -> String
dosifyPath = subst '/' '\\'