Markdown writer: use different width fences for nested divs.

Outer divs have longer fences. This aids clarity for the reader,
making it easier to see where the div ends. It also makes the
output compatible with some other implementations, e.g.
micromark, which require different-width fences for nesting.

Closes #9450.

1 files changed, 11 insertions, 2 deletions

diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 6338a90cd..941557e0e 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -401,9 +401,12 @@ blockToMarkdown' opts (Div attrs@(_,classes,_) bs)
                   let attrsToMd = if variant == Commonmark
                                   then attrsToMarkdown opts
                                   else classOrAttrsToMarkdown opts
-                  in nowrap (literal ":::" <+> attrsToMd attrs) $$
+                      divNesting = computeDivNestingLevel bs
+                      numcolons = 3 + divNesting
+                      colons = literal $ T.replicate numcolons ":"
+                  in nowrap (colons <+> attrsToMd attrs) $$
                      chomp contents $$
-                     literal ":::" <> blankline
+                     colons <> blankline
              | isEnabled Ext_native_divs opts ||
                (isEnabled Ext_raw_html opts &&
                 (variant == Commonmark ||
@@ -895,3 +898,9 @@ removeBlankLinesInHTML = T.pack . go False . T.unpack
         go !afternewline (!c:cs)
           | isSpace c = c : go afternewline cs
           | otherwise = c : go False cs
+
+computeDivNestingLevel :: [Block] -> Int
+computeDivNestingLevel = foldr go 0
+ where
+   go (Div _ bls') n = max (n + 1) (foldr go (n + 1) bls')
+   go _ n = n