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+{-
+Copyright (C) 2006-2015 John MacFarlane <jgm@berkeley.edu>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+-}
+{- |
+ Module : Text.Pandoc.Error
+ Copyright : Copyright (C) 2006-2015 John MacFarlane
+ License : GNU GPL, version 2 or above
+
+ Maintainer : John MacFarlane <jgm@berkeley.edu>
+ Stability : alpha
+ Portability : portable
+
+This module provides a standard way to deal with possible errors encounted
+during parsing.
+
+-}
+module Text.Pandoc.Error (PandocError(..), handleError) where
+
+import Text.Parsec.Error
+import Text.Parsec.Pos hiding (Line)
+import Text.Pandoc.Compat.Except
+
+type Input = String
+
+data PandocError = -- | Generic parse failure
+ ParseFailure String
+ -- | Error thrown by a Parsec parser
+ | ParsecError Input ParseError
+ deriving (Show)
+
+
+instance Error PandocError where
+ strMsg = ParseFailure
+
+
+-- | An unsafe method to handle `PandocError`s.
+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) ' ' ++
+ "^"
+