Add initial support for --color

ShellCheck/Checker.hs

@@ -48,6 +48,7 @@ checkScript sys spec = do
     results <- checkScript (csScript spec)
     return CheckResult {
         crFilename = csFilename spec,
+        crColorOption = csColorOption spec,
         crComments = results
     }
   where

ShellCheck/Formatter/TTY.hs

@@ -46,11 +46,11 @@ colorForLevel level =
         otherwise -> 0 -- none
 
 outputError file error = do
-    color <- getColorFunc
-    hPutStrLn stderr $ color "error" $ file ++ ": " ++ error
+    color <- getColorFunc $ ColorAuto -- FIXME: should respect --color
+    hPutStrLn stderr $ color "error ZZZ" $ file ++ ": " ++ error
 
 outputResult result contents = do
-    color <- getColorFunc
+    color <- getColorFunc $ crColorOption result
     let comments = crComments result
     let fileLines = lines contents
     let lineCount = fromIntegral $ length fileLines
@@ -75,10 +75,15 @@ cuteIndent comment =
 
 code code = "SC" ++ show code
 
-getColorFunc = do
+getColorFunc colorOption = do
     term <- hIsTerminalDevice stdout
     let windows = "mingw" `isPrefixOf` os
-    return $ if term && not windows then colorComment else const id
+    let isUsableTty = term && not windows
+    let useColor = case colorOption of
+                       ColorAlways -> True
+                       ColorNever -> False
+                       ColorAuto -> isUsableTty
+    return $ if useColor then colorComment else const id
   where
     colorComment level comment =
         ansi (colorForLevel level) ++ comment ++ clear

ShellCheck/Interface.hs

@@ -34,21 +34,30 @@ data CheckSpec = CheckSpec {
     csFilename :: String,
     csScript :: String,
     csExcludedWarnings :: [Integer],
+    csColorOption :: ColorOptions,
     csShellTypeOverride :: Maybe Shell
 } deriving (Show, Eq)
 
 data CheckResult = CheckResult {
     crFilename :: String,
-    crComments :: [PositionedComment]
+    crComments :: [PositionedComment],
+    crColorOption :: ColorOptions
 } deriving (Show, Eq)
 
 emptyCheckSpec = CheckSpec {
     csFilename = "",
     csScript = "",
     csExcludedWarnings = [],
-    csShellTypeOverride = Nothing
+    csShellTypeOverride = Nothing,
+    csColorOption = ColorAuto
 }
 
+data ColorOptions =
+    ColorAuto
+    | ColorAlways
+    | ColorNever
+  deriving (Ord, Eq, Show)
+
 -- Parser input and output
 data ParseSpec = ParseSpec {
     psFilename :: String,