Muse reader: add underline support in Emacs Muse mode

src/Text/Pandoc/Readers/Muse.hs

@@ -57,7 +57,7 @@ import Text.Pandoc.Logging
 import Text.Pandoc.Options
 import Text.Pandoc.Parsing
 import Text.Pandoc.Readers.HTML (htmlTag)
-import Text.Pandoc.Shared (crFilter)
+import Text.Pandoc.Shared (crFilter, underlineSpan)
 
 -- | Read Muse from an input string and return a Pandoc document.
 readMuse :: PandocMonad m
@@ -577,6 +577,7 @@ inlineList = [ endline
              , strongTag
              , emph
              , emphTag
+             , underlined
              , superscriptTag
              , subscriptTag
              , strikeoutTag
@@ -666,6 +667,11 @@ strong = fmap B.strong <$> emphasisBetween (string "**")
 emph :: PandocMonad m => MuseParser m (F Inlines)
 emph = fmap B.emph <$> emphasisBetween (char '*')
 
+underlined :: PandocMonad m => MuseParser m (F Inlines)
+underlined = do
+  guardDisabled Ext_amuse -- Supported only by Emacs Muse
+  fmap underlineSpan <$> emphasisBetween (char '_')
+
 emphTag :: PandocMonad m => MuseParser m (F Inlines)
 emphTag = inlineTag B.emph "em"
 

test/Tests/Readers/Muse.hs

@@ -10,6 +10,7 @@ import Tests.Helpers
 import Text.Pandoc
 import Text.Pandoc.Arbitrary ()
 import Text.Pandoc.Builder
+import Text.Pandoc.Shared (underlineSpan)
 -- import Text.Pandoc.Walk (walk)
 
 amuse :: Text -> Pandoc
@@ -83,6 +84,9 @@ tests =
           "***strength***" =?>
           para (strong . emph $ "strength")
 
+      , test emacsMuse "Underline"
+        ("_Underline_" =?> para (underlineSpan "Underline"))
+
       , "Superscript tag" =: "<sup>Superscript</sup>" =?> para (superscript "Superscript")
 
       , "Subscript tag" =: "<sub>Subscript</sub>" =?> para (subscript "Subscript")