Add json1 format that ignores tabs

The new json1 format works just like json except that it treats tabs as
single characters instead of 8-character tabstops.

The main use case is to allow editors to pass -fjson1 so that they can
consume the json output in a character-oriented way without breaking
backwards compatibility.

Also addresses #1048.

CHANGELOG.md

@@ -7,6 +7,7 @@
                    Enable with `-o` flags or `enable=name` directives
 - Source paths: Use `-P dir1:dir2` or a `source-path=dir1` directive
                 to specify search paths for sourced files.
+- json1 format like --format=json but treats tabs as single characters
 - SC2249: Warn about `case` with missing default case (verbose)
 - SC2248: Warn about unquoted variables without special chars (verbose)
 - SC2247: Warn about $"(cmd)" and $"{var}"

shellcheck.1.md

@@ -153,7 +153,7 @@ not warn at all, as `ksh` supports decimals in arithmetic contexts.
 
 :   Json is a popular serialization format that is more suitable for web
     applications. ShellCheck's json is compact and contains only the bare
-    minimum.
+    minimum.  Tabs are 8 characters.
 
         [
           {
@@ -167,6 +167,11 @@ not warn at all, as `ksh` supports decimals in arithmetic contexts.
           ...
         ]
 
+**json1**
+
+:   This is the same as shellcheck's json format, but tabs are treated as
+    single characters instead of 8-character tabstops.
+
 *quiet*
 
 :   Suppress all normal output. Exit with zero if no issues are found,

shellcheck.hs

@@ -141,7 +141,8 @@ formats :: FormatterOptions -> Map.Map String (IO Formatter)
 formats options = Map.fromList [
     ("checkstyle", ShellCheck.Formatter.CheckStyle.format),
     ("gcc",  ShellCheck.Formatter.GCC.format),
-    ("json", ShellCheck.Formatter.JSON.format),
+    ("json", ShellCheck.Formatter.JSON.format False),  -- JSON with 8-char tabs
+    ("json1", ShellCheck.Formatter.JSON.format True), -- JSON with 1-char tabs
     ("tty",  ShellCheck.Formatter.TTY.format options),
     ("quiet",  ShellCheck.Formatter.Quiet.format options)
     ]

src/ShellCheck/Formatter/Format.hs

@@ -22,6 +22,7 @@ module ShellCheck.Formatter.Format where
 import ShellCheck.Data
 import ShellCheck.Interface
 import ShellCheck.Fixer
+import Control.Monad
 import Data.Array
 
 -- A formatter that carries along an arbitrary piece of data
@@ -54,5 +55,10 @@ makeNonVirtual comments contents =
   where
     list = lines contents
     arr = listArray (1, length list) list
-    fix c = removeTabStops c arr
+    untabbedFix f = newFix {
+      fixReplacements = map (\r -> removeTabStops r arr) (fixReplacements f)
+    }
+    fix c = (removeTabStops c arr) {
+      pcFix = liftM untabbedFix (pcFix c)
+    }
 

src/ShellCheck/Formatter/JSON.hs

@@ -30,11 +30,12 @@ import GHC.Exts
 import System.IO
 import qualified Data.ByteString.Lazy.Char8 as BL
 
-format = do
+format :: Bool -> IO Formatter
+format removeTabs = do
     ref <- newIORef []
     return Formatter {
         header = return (),
-        onResult = collectResult ref,
+        onResult = collectResult removeTabs ref,
         onFailure = outputError,
         footer = finish ref
     }
@@ -96,8 +97,20 @@ instance ToJSON Fix where
         ]
 
 outputError file msg = hPutStrLn stderr $ file ++ ": " ++ msg
-collectResult ref result _ =
+
-    modifyIORef ref (\x -> crComments result ++ x)
+collectResult removeTabs ref cr sys = mapM_ f groups
+  where
+    comments = crComments cr
+    groups = groupWith sourceFile comments
+    f :: [PositionedComment] -> IO ()
+    f group = do
+        let filename = sourceFile (head group)
+        result <- siReadFile sys filename
+        let contents = either (const "") id result
+        let comments' = if removeTabs
+                        then makeNonVirtual comments contents
+                        else comments
+        modifyIORef ref (\x -> comments' ++ x)
 
 finish ref = do
     list <- readIORef ref