Add config file parsing.

[dead/lwn-epub.git] / src / CommandLine.hs

diff --git a/src/CommandLine.hs b/src/CommandLine.hs
index d9be034d5f5ec5734a753ede3d791458be0c28fd..455f7fd7a9416f0e417829ae9f6cad1020670c41 100644 (file)
--- a/src/CommandLine.hs
+++ b/src/CommandLine.hs
@@ -1,6 +1,10 @@
 {-# LANGUAGE DeriveDataTypeable #-}
 
-module CommandLine (Args(..), apply_args)
+module CommandLine (
+  Args(..),
+  apply_args,
+  program_name,
+  show_help)
 where
 
 -- Get the version from Cabal.
@@ -17,9 +21,12 @@ import System.Console.CmdArgs (
   argPos,
   cmdArgsApply,
   cmdArgsMode,
+  def,
   details,
+  help,
   program,
   typ,
+  typFile,
   summary
   )
 
@@ -33,7 +40,8 @@ import ExitCodes
 
 
 data Args =
-  Args { article :: String }
+  Args { output :: FilePath,
+         article :: String }
   deriving   (Show, Data, Typeable)
 
 
@@ -47,9 +55,15 @@ lwn_epub_summary :: String
 lwn_epub_summary =
   program_name ++ "-" ++ (showVersion version)
 
+output_help :: String
+output_help = "Output file, defaults to stdout"
+
 arg_spec :: Mode (CmdArgs Args)
 arg_spec = cmdArgsMode $
-             Args { article = "" &= argPos 0 &= typ "ARTICLE" }
+             Args {
+               output = def  &= typFile &= help output_help,
+               article = def &= argPos 0 &= typ "ARTICLE"
+             }
              &= program program_name
              &= summary lwn_epub_summary
              &= details [description]
@@ -60,6 +74,10 @@ is_missing_arg_error :: String -> Bool
 is_missing_arg_error s =
   startswith "Requires at least" s
 
+
+show_help :: IO (CmdArgs Args)
+show_help = withArgs ["--help"] parse_args
+
 parse_args :: IO (CmdArgs Args)
 parse_args = do
   x <- getArgs
@@ -68,14 +86,17 @@ parse_args = do
       Right result -> return result
       Left err ->
         if (is_missing_arg_error err) then
-          withArgs ["--help"] parse_args
+          -- Disregard the error message, show help instead.
+          show_help
         else do
           hPutStrLn stderr err
           exitWith (ExitFailure exit_args_parse_failed)
 
-        -- Disregard the error message, show help instead.
 
+-- | Really get the command-line arguments. This calls 'parse_args'
+--   first to replace the default "wrong number of arguments" error,
+--   and then runs 'cmdArgsApply' on the result to do what the
+--   'cmdArgs' function usually does.
 apply_args :: IO Args
-apply_args = do
-  x <- parse_args
-  cmdArgsApply x
+apply_args =
+  parse_args >>= cmdArgsApply