From f61d1bfa8a36e2f50fcfa7efc7612317d79da2a1 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Sat, 7 May 2016 22:45:25 +0200
Subject: Parse line input to argument list

---
 src/Command.hs | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

(limited to 'src/Command.hs')

diff --git a/src/Command.hs b/src/Command.hs
index fd21087..49dc966 100644
--- a/src/Command.hs
+++ b/src/Command.hs
@@ -5,6 +5,8 @@ module Command
        , parseCmd
        ) where
 
+import Data.Char (isSpace)
+
 import Types
 
 data Cmd = PerformAlt Alteration
@@ -12,6 +14,43 @@ data Cmd = PerformAlt Alteration
          | Step
          | UnknownCommand String
          | ParseError String
+         | Empty
 
 parseCmd :: SequenceM m => String -> m Cmd
-parseCmd input = return $ UnknownCommand input
+parseCmd = parseCmd' . split
+  where
+    split :: String -> [String]
+    split = reverse . split' [] "" Nothing Nothing
+    split' :: [String] -> String -> Maybe Char -> Maybe Char -> String -> [String]
+    split' ws w q e "" = trimStart $ (prepend q . append e $ reverse w):ws
+      where
+        prepend (Just c) = (c : )
+        prepend _ = id
+        append (Just c) = (++ [c])
+        append _ = id
+        trimStart ("":ws) = ws
+        trimStart ws = ws
+    split' ws w q e (c:cs)
+      | null w
+      , Nothing <- q
+      , Nothing <- e
+      , isQuote c           = split' ws w (Just c) Nothing cs -- Start quoted word at unescaped quote
+      | Nothing <- e
+      , (Just q') <- q
+      , c == q'             = split' (reverse w : ws) "" Nothing Nothing cs -- Close quoted word at unescaped quote of same type
+      | null w
+      , isSpace c
+      , Nothing <- e
+      , Nothing <- q        = split' ws w Nothing Nothing cs -- Ignore leading unescaped spaces if not within quotes
+      | isSpace c
+      , Nothing <- e
+      , Nothing <- q        = split' (reverse w : ws) "" Nothing Nothing cs -- Close unquoted word at unescaped space
+      | Nothing <- e
+      , isEscape c          = split' ws w q (Just c) cs -- Set escaped flag at unescaped escape char
+      | otherwise           = split' ws (c : w) q Nothing cs -- Append to word
+    isQuote q = q `elem` ['"', '\'']
+    isEscape e = e == '\\'
+
+parseCmd' :: SequenceM m => [String] -> m Cmd
+parseCmd' [] = return Empty
+parseCmd' (cmd:args) = return $ UnknownCommand (show $ cmd:args) -- DEBUG
-- 
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