{-# Language ScopedTypeVariables, PatternGuards, CPP #-}
module HsImport.Parse
( parseFile
) where
import qualified Data.Text.IO as TIO
import qualified Data.Text as T
import Data.Maybe (fromMaybe)
import Data.List (isPrefixOf)
import qualified Language.Haskell.Exts as HS
import Control.Exception (catch, SomeException)
#if __GLASGOW_HASKELL__ < 710
import Control.Applicative ((<$>))
#endif
type Error = String
type HsParseResult = HS.ParseResult (HS.Module HS.SrcSpanInfo)
parseFile :: FilePath -> IO (Either Error HsParseResult)
parseFile file = do
srcFile <- unlines. replaceCPPByComment . lines . T.unpack <$> TIO.readFile file
catch (do let result = parseFileContents srcFile
case result of
HS.ParseOk _ -> return $ Right result
HS.ParseFailed srcLoc _ -> do
srcResult <- parseInvalidSource (lines srcFile) (HS.srcLine srcLoc)
return $ Right $ fromMaybe result srcResult)
(\(e :: SomeException) -> do
let srcLines = lines srcFile
srcResult <- parseInvalidSource srcLines (length srcLines)
return $ maybe (Left $ show e) Right srcResult)
where
replaceCPPByComment = map $ \line ->
if "#" `isPrefixOf` line
then "-- fake hsimport comment"
else line
parseInvalidSource :: [String] -> Int -> IO (Maybe HsParseResult)
parseInvalidSource srcLines firstInvalidLine = do
parseInvalidSource' 1 firstInvalidLine Nothing 0
where
parseInvalidSource' :: Int -> Int -> Maybe (Int, HsParseResult) -> Int -> IO (Maybe HsParseResult)
parseInvalidSource' lastValidLine currLastLine maxParseOk iteration
| null srcLines || lastValidLine >= currLastLine
= return Nothing
| iteration >= 10
= return (snd <$> maxParseOk)
| otherwise = do
catch (case parseFileContents source of
result@(HS.ParseOk _)
| nextLine == currLastLine ->
return $ Just result
| otherwise ->
parseInvalidSource' nextLine currLastLine (maxParseOk' result) iteration'
HS.ParseFailed srcLoc _
| HS.srcLine srcLoc == firstInvalidLine ->
parseInvalidSource' lastValidLine nextLine maxParseOk iteration'
| otherwise ->
parseInvalidSource' nextLine currLastLine maxParseOk iteration')
(\(_ :: SomeException) -> parseInvalidSource' lastValidLine nextLine maxParseOk iteration')
where
source = unlines $ take nextLine srcLines
nextLine = lastValidLine + (floor ((realToFrac (currLastLine - lastValidLine) / 2) :: Double) :: Int)
iteration' = iteration + 1
maxParseOk' nextResult =
case maxParseOk of
Just (maxLine, _)
| nextLine > maxLine -> Just (nextLine, nextResult)
| otherwise -> maxParseOk
_ -> Just (nextLine, nextResult)
parseFileContents :: String -> HsParseResult
parseFileContents = HS.parseFileContentsWithMode parseMode
where
parseMode = HS.defaultParseMode { HS.fixities = Just [] }