Muse: add RTL support

Closes #5551

2 files changed, 21 insertions, 5 deletions

diff --git a/src/Text/Pandoc/Readers/Muse.hs b/src/Text/Pandoc/Readers/Muse.hs
index 568287929..ca7c94245 100644
--- a/src/Text/Pandoc/Readers/Muse.hs
+++ b/src/Text/Pandoc/Readers/Muse.hs
@@ -746,6 +746,8 @@ inline' = whitespace
       <|> strikeoutTag
       <|> verbatimTag
       <|> classTag
+      <|> inlineRtl
+      <|> inlineLtr
       <|> nbsp
       <|> linkOrImage
       <|> code
@@ -863,6 +865,16 @@ classTag = do
   classes <- maybe [] words . lookup "name" <$> openTag "class"
   fmap (B.spanWith ("", classes, [])) . mconcat <$> manyTill inline (closeTag "class")
 
+-- | Parse @\<\<\<RTL>>>@ text.
+inlineRtl :: PandocMonad m => MuseParser m (F Inlines)
+inlineRtl = try $
+  fmap (B.spanWith ("", [], [("dir", "rtl")])) . mconcat <$ string "<<<" <*> manyTill inline (string ">>>")
+
+-- | Parse @\<\<\<LTR>>>@ text.
+inlineLtr :: PandocMonad m => MuseParser m (F Inlines)
+inlineLtr = try $
+  fmap (B.spanWith ("", [], [("dir", "ltr")])) . mconcat <$ string ">>>" <*> manyTill inline (string "<<<")
+
 -- | Parse "~~" as nonbreaking space.
 nbsp :: PandocMonad m => MuseParser m (F Inlines)
 nbsp = try $ pure (B.str "\160") <$ string "~~"
diff --git a/src/Text/Pandoc/Writers/Muse.hs b/src/Text/Pandoc/Writers/Muse.hs
index c03fd0c1a..ec03d6292 100644
--- a/src/Text/Pandoc/Writers/Muse.hs
+++ b/src/Text/Pandoc/Writers/Muse.hs
@@ -377,6 +377,7 @@ shouldEscapeString s = do
            "::" `isInfixOf` s ||
            "~~" `isInfixOf` s ||
            "[[" `isInfixOf` s ||
+           ">>>" `isInfixOf` s ||
            ("]" `isInfixOf` s && insideLink) ||
            containsNotes '[' ']' s ||
            containsNotes '{' '}' s
@@ -412,7 +413,7 @@ removeKeyValues :: Inline -> Inline
 removeKeyValues (Code (i, cls, _) xs) = Code (i, cls, []) xs
 -- Do not remove attributes from Link
 -- Do not remove attributes, such as "width", from Image
-removeKeyValues (Span (i, cls, _) xs) = Span (i, cls, []) xs
+-- Do not remove attributes, such as "dir", from Span
 removeKeyValues x                     = x
 
 normalizeInlineList :: [Inline] -> [Inline]
@@ -682,14 +683,17 @@ inlineToMuse (Note contents) = do
   n <- gets stNoteNum
   let ref = show $ n + length notes
   return $ "[" <> text ref <> "]"
-inlineToMuse (Span (anchor,names,_) inlines) = do
+inlineToMuse (Span (anchor,names,kvs) inlines) = do
   contents <- inlineListToMuse inlines
+  let (contents', hasDir) = case lookup "dir" kvs of
+                              Just "rtl" -> ("<<<" <> contents <> ">>>", True)
+                              Just "ltr" -> (">>>" <> contents <> "<<<", True)
+                              _ -> (contents, False)
   let anchorDoc = if null anchor
                      then mempty
                      else text ('#':anchor) <> space
   modify $ \st -> st { stUseTags = False }
   return $ anchorDoc <> (if null inlines && not (null anchor)
                          then mempty
-                         else (if null names
-                               then "<class>"
-                               else "<class name=\"" <> text (head names) <> "\">") <> contents <> "</class>")
+                         else (if null names then (if hasDir then contents' else "<class>" <> contents' <> "</class>")
+                               else "<class name=\"" <> text (head names) <> "\">" <> contents' <> "</class>"))