Remove trailing whitespaces from the end of lines

src/Text/Pretty/Simple.hs

@@ -382,14 +382,14 @@ pHPrintStringNoColor = pHPrintStringOpt NoCheckColorTty defaultOutputOptionsNoCo
 -- | Like 'pShow', but without color.
 --
 -- >>> pShowNoColor [ Nothing, Just (1, "hello") ]
--- "[ Nothing\n, Just \n    ( 1\n    , \"hello\" \n    ) \n] "
+-- "[ Nothing\n, Just\n    ( 1\n    , \"hello\"\n    )\n]"
 pShowNoColor :: Show a => a -> Text
 pShowNoColor = pShowOpt defaultOutputOptionsNoColor
 
 -- | LIke 'pString', but without color.
 --
 -- >>> pStringNoColor $ show [1, 2, 3]
--- "[ 1\n, 2\n, 3\n] "
+-- "[ 1\n, 2\n, 3\n]"
 pStringNoColor :: String -> Text
 pStringNoColor = pStringOpt defaultOutputOptionsNoColor
 

src/Text/Pretty/Simple/Internal/OutputPrinter.hs

@@ -28,13 +28,13 @@ import Control.Applicative
 
 import Control.Monad.IO.Class (MonadIO, liftIO)
 import Control.Monad.Reader (MonadReader(ask, reader), runReader)
-import Data.Char (isPrint, ord)
+import Data.Char (isPrint, isSpace, ord)
 import Numeric (showHex)
 import Data.Foldable (fold)
 import Data.Text.Lazy (Text)
 import Data.Text.Lazy.Builder (Builder, fromString, toLazyText)
 import Data.Typeable (Typeable)
-import Data.List (intercalate)
+import Data.List (dropWhileEnd, intercalate)
 import Data.Maybe (fromMaybe)
 import Text.Read (readMaybe)
 import GHC.Generics (Generic)
@@ -297,7 +297,8 @@ sequenceFold = fmap fold . sequence
 -- An sample of an optimization is 'removeStartingNewLine' which just removes a
 -- newline if it is the first item in an 'Output' list.
 modificationsOutputList :: [Output] -> [Output]
-modificationsOutputList = shrinkWhitespaceInOthers . compressOthers . removeStartingNewLine
+modificationsOutputList =
+  removeTrailingSpacesInOtherBeforeNewLine . shrinkWhitespaceInOthers . compressOthers . removeStartingNewLine
 
 -- | Remove a 'OutputNewLine' if it is the first item in the 'Output' list.
 --
@@ -307,6 +308,22 @@ removeStartingNewLine :: [Output] -> [Output]
 removeStartingNewLine ((Output _ OutputNewLine) : t) = t
 removeStartingNewLine outputs = outputs
 
+-- | Remove trailing spaces from the end of a 'OutputOther' token if it is
+-- followed by a 'OutputNewLine', or if it is the final 'Output' in the list.
+-- This function assumes that there is a single 'OutputOther' before any
+-- 'OutputNewLine' (and before the end of the list), so it must be run after
+-- running 'compressOthers'.
+--
+-- >>> removeTrailingSpacesInOtherBeforeNewLine [Output 2 (OutputOther "foo  "), Output 4 OutputNewLine]
+-- [Output {outputNestLevel = NestLevel {unNestLevel = 2}, outputOutputType = OutputOther "foo"},Output {outputNestLevel = NestLevel {unNestLevel = 4}, outputOutputType = OutputNewLine}]
+removeTrailingSpacesInOtherBeforeNewLine :: [Output] -> [Output]
+removeTrailingSpacesInOtherBeforeNewLine [] = []
+removeTrailingSpacesInOtherBeforeNewLine (Output nest (OutputOther string):[]) =
+  (Output nest (OutputOther $ dropWhileEnd isSpace string)):[]
+removeTrailingSpacesInOtherBeforeNewLine (Output nest (OutputOther string):nl@(Output _ OutputNewLine):t) =
+  (Output nest (OutputOther $ dropWhileEnd isSpace string)):nl:removeTrailingSpacesInOtherBeforeNewLine t
+removeTrailingSpacesInOtherBeforeNewLine (h:t) = h : removeTrailingSpacesInOtherBeforeNewLine t
+
 -- | If there are two subsequent 'OutputOther' tokens, combine them into just
 -- one 'OutputOther'.
 --