-- |A simple feed generator: Error handling
--
--  Copyright (c) 2006 Manuel M T Chakravarty
--
--  License: <http://www.gnu.org/licenses/gpl.html>
--
--- Description ---------------------------------------------------------------
--
--  Language: Haskell 98
--

module Error (

  -- * Error formatting
  elementErrStr, 

  -- * Program termination
  abortWith, abortWithIO, exitSuccess

) where

-- hierachical libraries
import System.Environment (
  getProgName)
import System.Exit (
  ExitCode(..), exitWith, exitFailure)


-- Produce an error message for a given source, line range, and custom error
-- message.
--
elementErrStr :: String -> (Int, Int) -> String -> String
elementErrStr sname (start, end) err =
  sname ++ ":" ++ show start ++ "-" ++ show end ++": " ++ err

-- Terminate with a set of errors (in pure code).
--
abortWith :: [String] -> a
abortWith = error . ("FATAL ERROR" ++) . concat . map ('\n':)

-- Terminate with a set of errors (in IO code).
--
abortWithIO :: [String] -> IO a
abortWithIO errs =
  do
    name <- getProgName
    putStrLn $ name ++ ": FATAL ERROR"
    putStr (unlines errs)
    exitFailure

-- Terminate sucessfully.
--
exitSuccess :: IO a
exitSuccess = exitWith ExitSuccess