src/CommandLine.hs

   1 {-# LANGUAGE DeriveDataTypeable #-}
   2
   3 -- | The CommandLine module handles parsing of the command-line
   4 --   options.  It should more or less be a black box, providing Main
   5 --   with only the information it requires.
   6 --
   7 --   Which is why we're allowed all of this unsafe voodoo.
   8 --
   9 module CommandLine (
  10   Args(..),
  11   get_args
  12 )
  13 where
  14
  15 import System.Console.CmdArgs (
  16   Ann,
  17   Annotate( (:=) ),
  18   Data,
  19   Typeable,
  20   (+=),
  21   auto,
  22   cmdArgs_,
  23   def,
  24   details,
  25   explicit,
  26   groupname,
  27   help,
  28   helpArg,
  29   modes_,
  30   name,
  31   program,
  32   record,
  33   summary,
  34   versionArg )
  35
  36 -- Get the version from Cabal.
  37 import Paths_hath (version)
  38 import Data.Version (showVersion)
  39
  40 -- | The name of our program.
  41 program_name :: String
  42 program_name = "hath"
  43
  44 -- | A brief summary; displays the program name and version.
  45 my_summary :: String
  46 my_summary = program_name ++ "-" ++ (showVersion version)
  47
  48 barriers_help :: String
  49 barriers_help =
  50   "(regexed mode) place barriers in front/back of the regex " ++
  51   "to prevent e.g. '127.0.0.1' from matching '127.0.0.100'"
  52
  53
  54 -- | The Args type represents the possible command-line options. The
  55 --   duplication here seems necessary; CmdArgs' magic requires us to
  56 --   define some things explicitly.
  57 --
  58 --   The application currently has six modes (if this number is wrong,
  59 --   it means I forgot to update the comment!), all of which take the
  60 --   same options and arguments.
  61 --
  62 data Args =
  63   Regexed { barriers :: Bool } |
  64   Reduced { barriers :: Bool } |
  65   Duped { barriers :: Bool } |
  66   Diffed { barriers :: Bool } |
  67   Listed { barriers :: Bool }
  68   deriving (Data, Show, Typeable)
  69
  70 -- | Description of the 'Regexed' mode.
  71 regexed_description :: String
  72 regexed_description =
  73   "Compute a regular expression matching the input CIDRs."
  74
  75 -- | Description of the 'Reduced' mode.
  76 reduced_description :: String
  77 reduced_description =
  78   "Combine any redundant/adjacent CIDR blocks into one."
  79
  80 -- | Description of the 'Duped' mode.
  81 duped_description :: String
  82 duped_description = "Display what would be removed by 'reduced'."
  83
  84 -- | Description of the 'Diffed' mode.
  85 diffed_description :: String
  86 diffed_description =
  87   "Display both additions and deletions in a diff-like format."
  88
  89 -- | Description of the 'Listed' mode.
  90 listed_description :: String
  91 listed_description =
  92   "Enumerate the IP addresses contained within the input CIDRs."
  93
  94 -- | We use explicit annotation here because if we use the magic
  95 --   annotation, we have to duplicate the same argument definitions six
  96 --   times.
  97 --
  98 arg_spec :: Annotate Ann
  99 arg_spec =
 100   modes_ [regexed += auto, reduced, duped, diffed, listed]
 101     += program program_name
 102     += summary my_summary
 103     += helpArg [explicit,
 104                 name "help",
 105                 name "h",
 106                 groupname "Common flags"]
 107     += versionArg [explicit,
 108                    name "version",
 109                    name "v",
 110                    groupname "Common flags"]
 111   where
 112     make_mode :: (Bool -> Args) -> String -> (Annotate Ann)
 113     make_mode ctor desc =
 114       record (ctor def) [ barriers := def
 115                             += groupname "Common flags"
 116                             += help barriers_help ]
 117                         += details ["  " ++ desc]
 118
 119     regexed  = make_mode Regexed regexed_description
 120     reduced  = make_mode Reduced reduced_description
 121     duped    = make_mode Duped duped_description
 122     diffed   = make_mode Diffed diffed_description
 123     listed   = make_mode Listed listed_description
 124
 125 -- | This is the public interface; i.e. what main() should use to get
 126 --   the command-line arguments.
 127 get_args :: IO Args
 128 get_args = cmdArgs_ arg_spec