From: Michael Orlitzky <michael@orlitzky.com>
Date: Wed, 29 May 2013 19:21:30 +0000 (-0400)
Subject: Add command-line processing.
X-Git-Tag: 0.0.2~12
X-Git-Url: http://gitweb.michael.orlitzky.com/?p=email-validator.git;a=commitdiff_plain;h=a6d2e7470f17b44c0e8fe31c1268488a6788631f

Add command-line processing.
---

diff --git a/src/CommandLine.hs b/src/CommandLine.hs
new file mode 100644
index 0000000..1088f2a
--- /dev/null
+++ b/src/CommandLine.hs
@@ -0,0 +1,72 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+
+module CommandLine
+where
+
+import System.Console.CmdArgs
+import System.Console.CmdArgs.Explicit (process)
+import System.Environment (getArgs, withArgs)
+import System.Exit (ExitCode(..), exitWith)
+import System.IO (hPutStrLn, stderr)
+
+-- Get the version from Cabal.
+import Paths_email_validator (version)
+import Data.Version (showVersion)
+
+import ExitCodes
+
+-- We optionally accept input/output files to use instead of
+-- stdin/stdout.
+data Args = Args { input_file :: Maybe FilePath,
+                   output_file :: Maybe FilePath }
+  deriving   (Show, Data, Typeable)
+
+description :: String
+description = "Perform naive validation of email addresses."
+
+program_name :: String
+program_name = "email-validator"
+
+my_summary :: String
+my_summary = program_name ++ "-" ++ (showVersion version)
+
+input_file_help :: String
+input_file_help =
+  "Path to the input file (default: stdin), one email address per line"
+
+output_file_help :: String
+output_file_help =
+  "Path to the output file (default: stdout)"
+
+arg_spec :: Mode (CmdArgs Args)
+arg_spec =
+  cmdArgsMode $
+    Args { input_file  = def &= typFile &= help input_file_help,
+           output_file = def &= typFile &= help output_file_help }
+      &= program program_name
+      &= summary my_summary
+      &= details [description]
+
+show_help :: IO (CmdArgs Args)
+show_help = withArgs ["--help"] parse_args
+
+
+
+parse_args :: IO (CmdArgs Args)
+parse_args = do
+  x <- getArgs
+  let y = process arg_spec x
+  case y of
+    Right result -> return result
+    Left err -> do
+      hPutStrLn stderr err
+      exitWith (ExitFailure exit_args_parse_failed)
+
+
+-- | 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 =
+  parse_args >>= cmdArgsApply
diff --git a/src/ExitCodes.hs b/src/ExitCodes.hs
new file mode 100644
index 0000000..a48980f
--- /dev/null
+++ b/src/ExitCodes.hs
@@ -0,0 +1,12 @@
+-- | All exit codes that the program can return (excepting
+--   ExitSuccess). There's only one, since the program will try and
+--   fail forever upon errors.
+module ExitCodes
+where
+
+-- |Indicates that the command-line arguments could not be parsed.
+exit_args_parse_failed :: Int
+exit_args_parse_failed = 1
+
+exit_input_file_doesnt_exist :: Int
+exit_input_file_doesnt_exist = 2
diff --git a/src/Main.hs b/src/Main.hs
index bd3cc45..f38a7db 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,9 +1,11 @@
 {-# LANGUAGE DoAndIfThenElse #-}
+{-# LANGUAGE RecordWildCards #-}
 
 module Main
 where
 
 import Control.Concurrent.ParallelIO.Global (parallel, stopGlobalPool)
+import Control.Monad (when)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.UTF8 as BSU
 import Network.DNS (
@@ -14,9 +16,21 @@ import Network.DNS (
   makeResolvSeed,
   withResolver)
 import Network.DNS.Lookup (lookupMX)
-import System.IO (hGetContents, hFlush, hPutStrLn, stdin, stdout)
+import System.Directory (doesFileExist)
+import System.Exit (exitWith, ExitCode(..))
+import System.IO (
+  Handle,
+  IOMode( WriteMode ),
+  hClose,
+  hFlush,
+  openFile,
+  stdin,
+  stdout)
 import Text.Regex.PCRE.Light (compile, match, utf8)
 
+import CommandLine (Args(..), apply_args)
+import ExitCodes (exit_input_file_doesnt_exist)
+
 type Address = BSU.ByteString
 
 -- | Resolver parameters. We increase the default timeout from 3 to 5
@@ -96,19 +110,40 @@ validate resolver address = do
   else do
     return (address, False)
 
+
+append_handle_with_newline :: Handle -> BS.ByteString -> IO ()
+append_handle_with_newline h bs = do
+  BS.hPutStr h bs
+  BS.hPutStr h newline
+  where
+    newline = BSU.fromString "\n"
+
+
 main :: IO ()
 main = do
-  input <- hGetContents stdin
+  Args{..} <- apply_args
+
+  input <- case input_file of
+             Nothing   -> BS.hGetContents stdin
+             Just path -> do
+               is_file <- doesFileExist path
+               when (not is_file) $ do
+                 exitWith (ExitFailure exit_input_file_doesnt_exist)
+               BS.readFile path
 
-  let addresses = BSU.lines $ BSU.fromString input
+  output_handle <- case output_file of
+                     Nothing -> return stdout
+                     Just path -> openFile path WriteMode
+
+  let addresses = BSU.lines input
   let nonempty_addresses = filter (not . BS.null) addresses
 
   rs <- makeResolvSeed resolv_conf
   withResolver rs $ \resolver -> do
     let actions = map (validate resolver) nonempty_addresses
     results <- parallel actions
+    stopGlobalPool
     let good_pairs = filter snd results
-    mapM_ ((hPutStrLn stdout) . BSU.toString . fst) good_pairs
-
-  stopGlobalPool
-  hFlush stdout
+    mapM_ ((append_handle_with_newline output_handle) . fst) good_pairs
+    hFlush output_handle
+    hClose output_handle