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   (+=),
  20   auto,
  21   cmdArgs_,
  22   def,
  23   details,
  24   explicit,
  25   groupname,
  26   help,
  27   helpArg,
  28   modes_,
  29   name,
  30   program,
  31   record,
  32   summary,
  33   versionArg )
  34
  35 -- Get the version from Cabal.
  36 import Paths_hath (version)
  37 import Data.Version (showVersion)
  38
  39 -- | The name of our program.
  40 program_name :: String
  41 program_name = "hath"
  42
  43 -- | A brief summary; displays the program name and version.
  44 my_summary :: String
  45 my_summary = program_name ++ "-" ++ (showVersion version)
  46
  47 barriers_help :: String
  48 barriers_help =
  49   "(regexed mode) place barriers in front/back of the regex " ++
  50   "to prevent e.g. '127.0.0.1' from matching '127.0.0.100'"
  51
  52 normalize_help :: String
  53 normalize_help =
  54   "(reduced mode) normalize the output CIDRS, replacing any " ++
  55   "masked bits by zeros; e.g. '127.0.0.1/8' -> '127.0.0.0/8'"
  56
  57
  58 -- | The Args type represents the possible command-line options. The
  59 --   duplication here seems necessary; CmdArgs' magic requires us to
  60 --   define some things explicitly.
  61 --
  62 --   The application currently has five modes (if this number is wrong,
  63 --   it means I forgot to update the comment!), all of which take the
  64 --   same options and arguments.
  65 --
  66 data Args =
  67   Regexed { barriers :: Bool, normalize :: Bool } |
  68   Reduced { barriers :: Bool, normalize :: Bool } |
  69   Duped { barriers :: Bool, normalize :: Bool } |
  70   Diffed { barriers :: Bool, normalize :: Bool } |
  71   Listed { barriers :: Bool, normalize :: Bool }
  72   deriving (Data, Show)
  73
  74 -- | Description of the 'Regexed' mode.
  75 regexed_description :: String
  76 regexed_description =
  77   "Compute a regular expression matching the input CIDRs."
  78
  79 -- | Description of the 'Reduced' mode.
  80 reduced_description :: String
  81 reduced_description =
  82   "Combine any redundant/adjacent CIDR blocks into one."
  83
  84 -- | Description of the 'Duped' mode.
  85 duped_description :: String
  86 duped_description = "Display what would be removed by 'reduced'."
  87
  88 -- | Description of the 'Diffed' mode.
  89 diffed_description :: String
  90 diffed_description =
  91   "Display both additions and deletions in a diff-like format."
  92
  93 -- | Description of the 'Listed' mode.
  94 listed_description :: String
  95 listed_description =
  96   "Enumerate the IP addresses contained within the input CIDRs."
  97
  98 -- | We use explicit annotation here because if we use the magic
  99 --   annotation, we have to duplicate the same argument definitions six
 100 --   times.
 101 --
 102 arg_spec :: Annotate Ann
 103 arg_spec =
 104   modes_ [regexed += auto, reduced, duped, diffed, listed]
 105     += program program_name
 106     += summary my_summary
 107     += helpArg [explicit,
 108                 name "help",
 109                 name "h",
 110                 groupname "Common flags"]
 111     += versionArg [explicit,
 112                    name "version",
 113                    name "v",
 114                    groupname "Common flags"]
 115   where
 116     make_mode :: (Bool -> Bool -> Args) -> String -> (Annotate Ann)
 117     make_mode ctor desc =
 118       record (ctor def def)
 119                [ barriers := def
 120                    += groupname "Common flags"
 121                    += help barriers_help,
 122                  normalize := def
 123                    += groupname "Common flags"
 124                    += help normalize_help ]
 125                += details ["  " ++ desc]
 126
 127     regexed  = make_mode Regexed regexed_description
 128     reduced  = make_mode Reduced reduced_description
 129     duped    = make_mode Duped duped_description
 130     diffed   = make_mode Diffed diffed_description
 131     listed   = make_mode Listed listed_description
 132
 133 -- | This is the public interface; i.e. what main() should use to get
 134 --   the command-line arguments.
 135 get_args :: IO Args
 136 get_args = cmdArgs_ arg_spec