{-# LANGUAGE DeriveDataTypeable, DeriveGeneric #-} {- Copyright (C) 2006-2016 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) 2006-2016 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 GHC.Generics (Generic) import Data.Generics (Typeable) import Control.Exception (Exception) type Input = String data PandocError = -- | Generic parse failure ParseFailure String -- | Error thrown by a Parsec parser | ParsecError Input ParseError deriving (Show, Typeable, Generic) instance Exception PandocError -- | 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 ls = lines input ++ [""] errorInFile = if length ls > errLine - 1 then concat ["\n", (ls !! (errLine - 1)) ,"\n", replicate (errColumn - 1) ' ' ,"^"] else "" in error $ "\nError at " ++ show err' ++ errorInFile