src/CommandLine.hs

   1 {-# LANGUAGE DeriveDataTypeable #-}
   2
   3 module CommandLine
   4 where
   5
   6 import System.Console.CmdArgs
   7 import System.Console.CmdArgs.Explicit (process)
   8 import System.Environment (getArgs, withArgs)
   9 import System.Exit (ExitCode(..), exitWith)
  10 import System.IO (hPutStrLn, stderr)
  11
  12 -- Get the version from Cabal.
  13 import Paths_email_validator (version)
  14 import Data.Version (showVersion)
  15
  16 import ExitCodes
  17
  18 -- We optionally accept input/output files to use instead of
  19 -- stdin/stdout.
  20 data Args = Args { input_file :: Maybe FilePath,
  21                    output_file :: Maybe FilePath }
  22   deriving   (Show, Data, Typeable)
  23
  24 description :: String
  25 description = "Perform naive validation of email addresses."
  26
  27 program_name :: String
  28 program_name = "email-validator"
  29
  30 my_summary :: String
  31 my_summary = program_name ++ "-" ++ (showVersion version)
  32
  33 input_file_help :: String
  34 input_file_help =
  35   "Path to the input file (default: stdin), one email address per line"
  36
  37 output_file_help :: String
  38 output_file_help =
  39   "Path to the output file (default: stdout)"
  40
  41 arg_spec :: Mode (CmdArgs Args)
  42 arg_spec =
  43   cmdArgsMode $
  44     Args { input_file  = def &= typFile &= help input_file_help,
  45            output_file = def &= typFile &= help output_file_help }
  46       &= program program_name
  47       &= summary my_summary
  48       &= details [description]
  49
  50 show_help :: IO (CmdArgs Args)
  51 show_help = withArgs ["--help"] parse_args
  52
  53
  54
  55 parse_args :: IO (CmdArgs Args)
  56 parse_args = do
  57   x <- getArgs
  58   let y = process arg_spec x
  59   case y of
  60     Right result -> return result
  61     Left err -> do
  62       hPutStrLn stderr err
  63       exitWith (ExitFailure exit_args_parse_failed)
  64
  65
  66 -- | Really get the command-line arguments. This calls 'parse_args'
  67 --   first to replace the default "wrong number of arguments" error,
  68 --   and then runs 'cmdArgsApply' on the result to do what the
  69 --   'cmdArgs' function usually does.
  70 apply_args :: IO Args
  71 apply_args =
  72   parse_args >>= cmdArgsApply