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module Text.Pandoc.Error (PandocError(..), handleError,hush, mapLeft) where
import Text.Parsec.Error
import Text.Parsec.Pos hiding (Line)
import Text.Pandoc.Compat.Except
type Input = String
data PandocError = ParseFailure String
| ParsecError Input ParseError
deriving (Show)
instance Error PandocError where
strMsg = ParseFailure
mapLeft :: (a -> b) -> Either a c -> Either b c
mapLeft f (Left x) = Left (f x)
mapLeft _ (Right x) = Right x
hush :: Either a b -> Maybe b
hush (Left _) = Nothing
hush (Right x) = Just x
handleError :: Either PandocError a -> a
handleError (Right r) = r
handleError (Left err) =
case err of
ParseFailure string -> error string
ParsecError input err' ->
let errPos = errorPos err'
errLine = sourceLine errPos
errColumn = sourceColumn errPos
theline = (lines input ++ [""]) !! (errLine - 1)
in error $ "\nError at " ++ show err' ++ "\n" ++
theline ++ "\n" ++ replicate (errColumn - 1) ' ' ++
"^"
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