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