hledger/hledger-lib/Hledger/Utils/UTF8IOCompat.hs

{-# LANGUAGE CPP #-}
{- |

UTF-8 aware string IO functions that will work across multiple platforms
and GHC versions. Includes code from Text.Pandoc.UTF8 ((C) 2010 John
MacFarlane).

Example usage:

 import Prelude hiding (readFile,writeFile,appendFile,getContents,putStr,putStrLn)
 import UTF8IOCompat   (readFile,writeFile,appendFile,getContents,putStr,putStrLn)
 import UTF8IOCompat   (SystemString,fromSystemString,toSystemString,error',userError')

2013/4/10 update: we now trust that current GHC versions & platforms
do the right thing, so this file is a no-op and on its way to being removed.
Not carefully tested.

2019/10/20 update: all packages have base>=4.9 which corresponds to GHC v8.0.1
and higher. Tear this file apart!

-}
-- TODO obsolete ?

module Hledger.Utils.UTF8IOCompat (
  readFile,
  writeFile,
  appendFile,
  getContents,
  hGetContents,
  putStr,
  putStrLn,
  hPutStr,
  hPutStrLn,
  --
  error',
  userError',
  usageError,
)
where

-- import Control.Monad (liftM)
-- import qualified Data.ByteString.Lazy as B
-- import qualified Data.ByteString.Lazy.Char8 as B8
-- import qualified Data.ByteString.Lazy.UTF8 as U8 (toString, fromString)
import Prelude hiding (readFile, writeFile, appendFile, getContents, putStr, putStrLn)
import System.IO -- (Handle)

-- bom :: B.ByteString
-- bom = B.pack [0xEF, 0xBB, 0xBF]

-- stripBOM :: B.ByteString -> B.ByteString
-- stripBOM s | bom `B.isPrefixOf` s = B.drop 3 s
-- stripBOM s = s

-- readFile :: FilePath -> IO String
-- readFile = liftM (U8.toString . stripBOM) . B.readFile

-- writeFile :: FilePath -> String -> IO ()
-- writeFile f = B.writeFile f . U8.fromString

-- appendFile :: FilePath -> String -> IO ()
-- appendFile f = B.appendFile f . U8.fromString

-- getContents :: IO String
-- getContents = liftM (U8.toString . stripBOM) B.getContents

-- hGetContents :: Handle -> IO String
-- hGetContents h = liftM (U8.toString . stripBOM) (B.hGetContents h)

-- putStr :: String -> IO ()
-- putStr = bs_putStr . U8.fromString

-- putStrLn :: String -> IO ()
-- putStrLn = bs_putStrLn . U8.fromString

-- hPutStr :: Handle -> String -> IO ()
-- hPutStr h = bs_hPutStr h . U8.fromString

-- hPutStrLn :: Handle -> String -> IO ()
-- hPutStrLn h = bs_hPutStrLn h . U8.fromString

-- -- span GHC versions including 6.12.3 - 7.4.1:
-- bs_putStr         = B8.putStr
-- bs_putStrLn       = B8.putStrLn
-- bs_hPutStr        = B8.hPut
-- bs_hPutStrLn h bs = B8.hPut h bs >> B8.hPut h (B.singleton 0x0a)

-- | A SystemString-aware version of error.
error' :: String -> a
error' =
#if __GLASGOW_HASKELL__ < 800
-- (easier than if base < 4.9)
  error
#else
  errorWithoutStackTrace
#endif

-- | A SystemString-aware version of userError.
userError' :: String -> IOError
userError' = userError

-- | A SystemString-aware version of error that adds a usage hint.
usageError :: String -> a
usageError = error' . (++ " (use -h to see usage)")