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
  53 -- | The Args type represents the possible command-line options. The
  54 --   duplication here seems necessary; CmdArgs' magic requires us to
  55 --   define some things explicitly.
  56 --
  57 --   The application currently has six modes (if this number is wrong,
  58 --   it means I forgot to update the comment!), all of which take the
  59 --   same options and arguments.
  60 --
  61 data Args =
  62   Regexed { barriers :: Bool } |
  63   Reduced { barriers :: Bool } |
  64   Duped { barriers :: Bool } |
  65   Diffed { barriers :: Bool } |
  66   Listed { barriers :: Bool }
  67   deriving (Data, Show)
  68
  69 -- | Description of the 'Regexed' mode.
  70 regexed_description :: String
  71 regexed_description =
  72   "Compute a regular expression matching the input CIDRs."
  73
  74 -- | Description of the 'Reduced' mode.
  75 reduced_description :: String
  76 reduced_description =
  77   "Combine any redundant/adjacent CIDR blocks into one."
  78
  79 -- | Description of the 'Duped' mode.
  80 duped_description :: String
  81 duped_description = "Display what would be removed by 'reduced'."
  82
  83 -- | Description of the 'Diffed' mode.
  84 diffed_description :: String
  85 diffed_description =
  86   "Display both additions and deletions in a diff-like format."
  87
  88 -- | Description of the 'Listed' mode.
  89 listed_description :: String
  90 listed_description =
  91   "Enumerate the IP addresses contained within the input CIDRs."
  92
  93 -- | We use explicit annotation here because if we use the magic
  94 --   annotation, we have to duplicate the same argument definitions six
  95 --   times.
  96 --
  97 arg_spec :: Annotate Ann
  98 arg_spec =
  99   modes_ [regexed += auto, reduced, duped, diffed, listed]
 100     += program program_name
 101     += summary my_summary
 102     += helpArg [explicit,
 103                 name "help",
 104                 name "h",
 105                 groupname "Common flags"]
 106     += versionArg [explicit,
 107                    name "version",
 108                    name "v",
 109                    groupname "Common flags"]
 110   where
 111     make_mode :: (Bool -> Args) -> String -> (Annotate Ann)
 112     make_mode ctor desc =
 113       record (ctor def) [ barriers := def
 114                             += groupname "Common flags"
 115                             += help barriers_help ]
 116                         += details ["  " ++ desc]
 117
 118     regexed  = make_mode Regexed regexed_description
 119     reduced  = make_mode Reduced reduced_description
 120     duped    = make_mode Duped duped_description
 121     diffed   = make_mode Diffed diffed_description
 122     listed   = make_mode Listed listed_description
 123
 124 -- | This is the public interface; i.e. what main() should use to get
 125 --   the command-line arguments.
 126 get_args :: IO Args
 127 get_args = cmdArgs_ arg_spec