From 4d1402a1a7d87767267d48a77998e4fb13395b31 Mon Sep 17 00:00:00 2001
From: Pavan Rikhi <pavan.rikhi@gmail.com>
Date: Sat, 17 Mar 2018 22:48:24 -0400
Subject: Split Modules into Library & Executable Structure

Move the Main module to a new `app` directory. All other modules have
been nested under the `Xmobar` name. Lots of module headers & imports
were updated.
---
 src/Xmobar/Environment.hs | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 src/Xmobar/Environment.hs

(limited to 'src/Xmobar/Environment.hs')

diff --git a/src/Xmobar/Environment.hs b/src/Xmobar/Environment.hs
new file mode 100644
index 0000000..8a9223a
--- /dev/null
+++ b/src/Xmobar/Environment.hs
@@ -0,0 +1,49 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  XMobar.Environment
+-- Copyright   :  (c) William Song
+-- License     :  BSD-style (see LICENSE)
+--
+-- Maintainer  :  Will Song <incertia@incertia.net>
+-- Stability   :  stable
+-- Portability :  portable
+--
+-- A function to expand environment variables in strings
+--
+-----------------------------------------------------------------------------
+module Xmobar.Environment(expandEnv) where
+
+import Control.Applicative  ((<$>))
+import Data.Maybe           (fromMaybe)
+import System.Environment   (lookupEnv)
+
+expandEnv :: String -> IO String
+expandEnv "" = return ""
+expandEnv (c:s) = case c of
+  '$'       -> do
+    envVar <- fromMaybe "" <$> lookupEnv e
+    remainder <- expandEnv s'
+    return $ envVar ++ remainder
+    where (e, s') = getVar s
+          getVar "" = ("", "")
+          getVar ('{':s'') = (takeUntil "}" s'', drop 1 . dropUntil "}" $ s'')
+          getVar s'' = (takeUntil filterstr s'', dropUntil filterstr s'')
+          filterstr = ",./? \t;:\"'~`!@#$%^&*()<>-+=\\|"
+          takeUntil f = takeWhile (not . flip elem f)
+          dropUntil f = dropWhile (not . flip elem f)
+
+  '\\' -> case s == "" of
+    True  -> return "\\"
+    False -> do
+      remainder <- expandEnv $ drop 1 s
+      return $ escString s ++ remainder
+      where escString s' = let (cc:_) = s' in
+              case cc of
+                't' -> "\t"
+                'n' -> "\n"
+                '$' -> "$"
+                _   -> [cc]
+
+  _    -> do
+    remainder <- expandEnv s
+    return $ c : remainder
-- 
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