Make indentation configurable via --tabsize; closes #210

elm-format.cabal

@@ -60,6 +60,7 @@ library
         AST.V0_16
         AST.Variable
         Box
+        Defaults
         Elm.Utils
         ElmFormat.Cli
         ElmFormat.Parse

parser/src/Reporting/Report.hs

@@ -15,6 +15,7 @@ import System.IO (hPutStr, stderr)
 
 import qualified Reporting.Region as R
 
+import Defaults
 
 data Report = Report
     { _title :: String
@@ -106,7 +107,7 @@ ansi tipe =
 messageBar :: Renderer m -> String -> String -> m ()
 messageBar renderer tag location =
   let
-    usedSpace = 4 + length tag + 1 + length location
+    usedSpace = defaultTabSize + length tag + 1 + length location
   in
     header renderer $
       "-- " ++ tag ++ " "

src/Box.hs

@@ -16,7 +16,7 @@ import qualified Data.Text as T
 A line is ALWAYS just one line.
 
 Space is self-explanatory,
-  Tab aligns to the nearest multiple of 4 spaces,
+  Tab aligns to the nearest multiple of Config._tabsize spaces,
   Text brings any string into the data structure,
   Row joins more of these elements onto one line.
 -}
@@ -183,10 +183,10 @@ xyz
 myPrefix abcde
          xyz
 -}
-prefix :: Line -> Box -> Box
-prefix pref =
+prefix :: Int -> Line -> Box -> Box
+prefix tabSize pref =
     let
-        prefixLength = lineLength 0 pref
+        prefixLength = lineLength tabSize 0 pref
         paddingSpaces = replicate prefixLength space
         padLineWithSpaces l = row [ row paddingSpaces, l ]
         addPrefixToLine l = row [ pref, l ]
@@ -205,57 +205,52 @@ addSuffix suffix b =
                 |> andThen [ line $ row [ last ls, suffix ] ]
 
 
-renderLine :: Int -> Line -> T.Text
-renderLine startColumn line' =
+renderLine :: Int -> Int -> Line -> T.Text
+renderLine tabSize startColumn line' =
     case line' of
         Text text ->
             text
         Space ->
             T.singleton ' '
         Tab ->
-            T.pack $ replicate (tabLength startColumn) ' '
+            T.pack $ replicate (tabLength tabSize startColumn) ' '
         Row lines' ->
-            renderRow startColumn lines'
+            renderRow tabSize startColumn lines'
 
 
-render :: Box -> T.Text
-render box' =
+render :: Int -> Box -> T.Text
+render tabSize box' =
     case box' of
         SingleLine line' ->
-            T.snoc (renderLine 0 line') '\n'
+            T.snoc (renderLine tabSize 0 line') '\n'
         Stack l1 l2 rest ->
-            T.unlines $ map (renderLine 0) (l1 : l2 : rest)
+            T.unlines $ map (renderLine tabSize 0) (l1 : l2 : rest)
         MustBreak line' ->
-            T.snoc (renderLine 0 line') '\n'
+            T.snoc (renderLine tabSize 0 line') '\n'
 
 
-lineLength :: Int -> Line -> Int
-lineLength startColumn line' =
+lineLength :: Int -> Int -> Line -> Int
+lineLength tabSize startColumn line' =
    startColumn +
       case line' of
          Text string -> T.length string
          Space -> 1
-         Tab -> tabLength startColumn
-         Row lines' -> rowLength startColumn lines'
+         Tab -> tabLength tabSize startColumn
+         Row lines' -> rowLength tabSize startColumn lines'
 
 
 initRow :: Int -> (T.Text, Int)
 initRow startColumn =
   (T.empty, startColumn)
 
 
-spacesInTab :: Int
-spacesInTab =
-  4
+spacesToNextTab :: Int -> Int -> Int
+spacesToNextTab tabSize startColumn =
+  startColumn `mod` tabSize
 
-
-spacesToNextTab :: Int -> Int
-spacesToNextTab startColumn =
-  startColumn `mod` spacesInTab
-
-tabLength :: Int -> Int
-tabLength startColumn =
-  spacesInTab - (spacesToNextTab startColumn)
+tabLength :: Int -> Int -> Int
+tabLength tabSize startColumn =
+  tabSize - (spacesToNextTab tabSize startColumn)
 
 {-
 What happens here is we take a row and start building its contents
@@ -282,31 +277,32 @@ The (T.Text, Int) type here means the (string, column) from the table above.
 Then we just need to do one final modification to get from endColumn to resultLength,
   which is what we are after in the function `rowLength`.
 -}
-renderRow' :: Int -> [Line] -> (T.Text, Int)
-renderRow' startColumn lines' =
+renderRow' :: Int -> Int -> [Line] -> (T.Text, Int)
+renderRow' tabSize startColumn lines' =
   (result, resultLength)
   where
-    (result, endColumn) = foldl addLine (initRow startColumn) lines'
+    addLine' = addLine tabSize
+    (result, endColumn) = foldl addLine' (initRow startColumn) lines'
     resultLength = endColumn - startColumn
 
 {-
 A step function for renderRow'.
 
-addLine (" ",1) Tab == ("    ",4)
+addLine ... (" ",1) Tab == ... ("    ",Flags.Config._tabsize)
 -}
-addLine :: (T.Text, Int) -> Line -> (T.Text, Int)
-addLine (string, startColumn') line' =
+addLine :: Int -> (T.Text, Int) -> Line -> (T.Text, Int)
+addLine tabSize (string, startColumn') line' =
   (newString, newStartColumn)
   where
-    newString = T.append string $ renderLine startColumn' line'
-    newStartColumn = lineLength startColumn' line'
+    newString = T.append string $ renderLine tabSize startColumn' line'
+    newStartColumn = lineLength tabSize startColumn' line'
 
 -- Extract the final string from renderRow'
-renderRow :: Int -> [Line] -> T.Text
-renderRow startColumn lines' =
-  fst $ renderRow' startColumn lines'
+renderRow :: Int -> Int -> [Line] -> T.Text
+renderRow tabSize startColumn lines' =
+  fst $ renderRow' tabSize startColumn lines'
 
 -- Extract the final length from renderRow'
-rowLength :: Int -> [Line] -> Int
-rowLength startColumn lines' =
-  snd $ renderRow' startColumn lines'
+rowLength :: Int -> Int -> [Line] -> Int
+rowLength tabSize startColumn lines' =
+  snd $ renderRow' tabSize startColumn lines'

src/Defaults.hs

@@ -0,0 +1,9 @@
+{-# OPTIONS_GHC -Wall #-}
+module Defaults where
+
+
+-- Configurable indentation
+--
+-- See: https://github.com/avh4/elm-format/issues/210
+defaultTabSize :: Int
+defaultTabSize = 4

src/ElmFormat.hs

@@ -37,17 +37,18 @@ import qualified Reporting.Result as Result
 writeResult
     :: Operation f =>
     ElmVersion
+    -> Int
     -> Destination
     -> FilePath
     -> Text.Text
     -> Result.Result () Syntax.Error AST.Module.Module
     -> Free f (Maybe Bool)
-writeResult elmVersion destination inputFile inputText result =
+writeResult elmVersion tabSize destination inputFile inputText result =
     case result of
         Result.Result _ (Result.Ok modu) ->
             let
                 renderedText =
-                    Render.render elmVersion modu
+                    Render.render elmVersion tabSize modu
                 rendered =
                     renderedText
                         |> Text.encodeUtf8
@@ -82,17 +83,17 @@ writeResult elmVersion destination inputFile inputText result =
             >> return (Just False)
 
 
-processTextInput :: Operation f => ElmVersion -> Destination -> FilePath -> Text.Text -> Free f (Maybe Bool)
-processTextInput elmVersion destination inputFile inputText =
+processTextInput :: Operation f => ElmVersion -> Int -> Destination -> FilePath -> Text.Text -> Free f (Maybe Bool)
+processTextInput elmVersion tabSize destination inputFile inputText =
     Parse.parse inputText
-        |> writeResult elmVersion destination inputFile inputText
+        |> writeResult elmVersion tabSize destination inputFile inputText
 
 
-processFileInput :: Operation f => ElmVersion -> FilePath -> Destination -> Free f (Maybe Bool)
-processFileInput elmVersion inputFile destination =
+processFileInput :: Operation f => ElmVersion -> Int -> FilePath -> Destination -> Free f (Maybe Bool)
+processFileInput elmVersion tabSize inputFile destination =
     do
         inputText <- Operation.deprecatedIO $ fmap Text.decodeUtf8 $ ByteString.readFile inputFile
-        processTextInput elmVersion destination inputFile inputText
+        processTextInput elmVersion tabSize destination inputFile inputText
 
 
 resolveFile :: FileStore f => FilePath -> Free f (Either InputFileMessage [FilePath])
@@ -147,8 +148,8 @@ resolveFiles inputFiles =
                 return $ Right $ concat files
 
 
-handleFilesInput :: Operation f => ElmVersion -> [FilePath] -> Maybe FilePath -> Bool -> Bool -> Free f (Maybe Bool)
-handleFilesInput elmVersion inputFiles outputFile autoYes validateOnly =
+handleFilesInput :: Operation f => ElmVersion -> Int -> [FilePath] -> Maybe FilePath -> Bool -> Bool -> Free f (Maybe Bool)
+handleFilesInput elmVersion tabSize inputFiles outputFile autoYes validateOnly =
     do
         elmFiles <- resolveFiles inputFiles
 
@@ -169,7 +170,7 @@ handleFilesInput elmVersion inputFiles outputFile autoYes validateOnly =
                         do
                             let destination = if validateOnly then ValidateOnly else ToFile realOutputFile'
                             onInfo $ ProcessingFiles [inputFile]
-                            processFileInput elmVersion inputFile destination
+                            processFileInput elmVersion tabSize inputFile destination
 
             Right elmFiles -> do
                 when (isJust outputFile)
@@ -195,7 +196,7 @@ handleFilesInput elmVersion inputFiles outputFile autoYes validateOnly =
                         in
                             do
                                 onInfo $ ProcessingFiles elmFiles
-                                validationResults <- mapM (\file -> processFileInput elmVersion file (dst file)) elmFiles
+                                validationResults <- mapM (\file -> processFileInput elmVersion tabSize file (dst file)) elmFiles
                                 return $ foldl merge Nothing validationResults
                     else
                         return Nothing
@@ -257,8 +258,8 @@ determineWhatToDoFromConfig config =
         determineWhatToDo source destination
 
 
-validate :: Operation f => ElmVersion -> Source -> Free f Bool
-validate elmVersion source =
+validate :: Operation f => ElmVersion -> Int -> Source -> Free f Bool
+validate elmVersion tabSize source =
     do
         result <-
             case source of
@@ -268,10 +269,10 @@ validate elmVersion source =
 
                         Lazy.toStrict input
                             |> Text.decodeUtf8
-                            |> processTextInput elmVersion ValidateOnly "<STDIN>"
+                            |> processTextInput elmVersion tabSize ValidateOnly "<STDIN>"
 
                 FromFiles first rest ->
-                    handleFilesInput elmVersion (first:rest) Nothing True True
+                    handleFilesInput elmVersion tabSize (first:rest) Nothing True True
 
         case result of
             Nothing ->
@@ -320,6 +321,7 @@ main defaultVersion =
     do
         config <- Flags.parse defaultVersion elmFormatVersion experimental
         let autoYes = Flags._yes config
+        let tabSize = Flags._tabSize config
         let elmVersionResult = determineVersion (Flags._elmVersion config) (Flags._upgrade config)
 
         case (elmVersionResult, determineWhatToDoFromConfig config) of
@@ -336,13 +338,13 @@ main defaultVersion =
             (Right elmVersion, Right (Validate source)) ->
                 do
                     isSuccess <-
-                        validate elmVersion source
+                        validate elmVersion tabSize source
                             |> Execute.run (Execute.forMachine elmVersion)
                     exit isSuccess
 
             (Right elmVersion, Right (FormatInPlace first rest)) ->
                 do
-                    result <- foldFree Execute.forHuman $ handleFilesInput elmVersion (first:rest) Nothing autoYes False
+                    result <- foldFree Execute.forHuman $ handleFilesInput elmVersion tabSize (first:rest) Nothing autoYes False
                     case result of
                         Just False ->
                             exitFailure
@@ -352,7 +354,7 @@ main defaultVersion =
 
             (Right elmVersion, Right (FormatToFile input output)) ->
                 do
-                    result <- foldFree Execute.forHuman $ handleFilesInput elmVersion [input] (Just output) autoYes False
+                    result <- foldFree Execute.forHuman $ handleFilesInput elmVersion tabSize [input] (Just output) autoYes False
                     case result of
                         Just False ->
                             exitFailure
@@ -367,7 +369,7 @@ main defaultVersion =
                     result <-
                         Lazy.toStrict input
                             |> Text.decodeUtf8
-                            |> processTextInput elmVersion UpdateInPlace "<STDIN>"
+                            |> processTextInput elmVersion tabSize UpdateInPlace "<STDIN>"
                             |> foldFree Execute.forHuman
                     case result of
                         Just False ->
@@ -383,7 +385,7 @@ main defaultVersion =
                     result <-
                         Lazy.toStrict input
                             |> Text.decodeUtf8
-                            |> processTextInput elmVersion (ToFile output) "<STDIN>"
+                            |> processTextInput elmVersion tabSize (ToFile output) "<STDIN>"
                             |> foldFree Execute.forHuman
                     case result of
                         Just False ->