Introduce denotations, buttonize links in emacs

Styled elements now can be denoted, so that the emacs interface can
buttonize links, while it is still easy to ignore the semantics and
just render those elements.

The emacs interface is more mouse- and TAB-friendly now.

1 files changed, 31 insertions, 4 deletions

diff --git a/Pancake/Printing.hs b/Pancake/Printing.hs
index a385751..2e0aee5 100644
--- a/Pancake/Printing.hs
+++ b/Pancake/Printing.hs
@@ -25,12 +25,13 @@ propertize :: Terminal -> Styled -> TermOutput
 propertize _ (Plain s) = termText s
 propertize t (Fg clr s) = maybe id (\f -> f clr)
   (getCapability t withForegroundColor) $ propertize t s
-propertize t (Pancake.Rendering.Bold s) =
+propertize t (Bold s) =
   maybe id id (getCapability t withBold) $ propertize t s
-propertize t (Pancake.Rendering.Emph s) =
+propertize t (Emph s) =
   maybe id id (getCapability t withStandout) $ propertize t s
-propertize t (Pancake.Rendering.Underline s) =
+propertize t (Underline s) =
   maybe id id (getCapability t withUnderline) $ propertize t s
+propertize t (Denote _ s) = propertize t s
 
 -- | Prints rendered lines.
 showLines :: MonadIO m => [StyledLine] -> m ()
@@ -57,7 +58,7 @@ showSexps uri ro =
   -- abandoned, and the task is simple enough to do it here
   putSexpLn [ "render"
             , list $ "lines" :
-              map (list . pure . concat . intersperse " " . map showSexp)
+              map (list . pure . concat . intersperse " " . map showSexp . mergeStyled)
               (rLines ro)
             , list $ "identifiers"
               : map (\(i, l) -> list [encodeStr i, show l]) (rIdentifiers ro)
@@ -76,3 +77,29 @@ showSexps uri ro =
     showSexp (Bold s) = list ["style", "bold", showSexp s]
     showSexp (Underline s) = list ["style", "underline", showSexp s]
     showSexp (Emph s) = list ["style", "italic", showSexp s]
+    showSexp (Denote d s) = list [ "denotation"
+                                 , showDenotation d
+                                 , showSexp s]
+    showDenotation :: Denotation -> String
+    showDenotation (Link u) = list ["link", ".", encodeStr $ show u]
+    showDenotation (Math m) = list ["math", ".", encodeStr m]
+
+mergeStyled :: [Styled] -> [Styled]
+mergeStyled = foldr mergeStyled' []
+  where
+    mergeStyled' :: Styled -> [Styled] -> [Styled]
+    mergeStyled' s [] = [s]
+    mergeStyled' s (s':rest) = maybe (s:s':rest) (: rest) (tryMerge s s')
+
+tryMerge :: Styled -> Styled -> Maybe Styled
+tryMerge (Plain s) (Plain s') = pure $ Plain $ s ++ s'
+tryMerge (Fg clr s) (Fg clr' s')
+  | clr == clr' = Fg clr <$> tryMerge s s'
+  | otherwise = mzero
+tryMerge (Bold s) (Bold s') = Bold <$> tryMerge s s'
+tryMerge (Underline s) (Underline s') = Underline <$> tryMerge s s'
+tryMerge (Emph s) (Emph s') = Emph <$> tryMerge s s'
+tryMerge (Denote d s) (Denote d' s')
+  | d == d' = Denote d <$> tryMerge s s'
+  | otherwise = mzero
+tryMerge _ _ = mzero