LibMarkdown: Better support for code fences

- Support tildes.
- Support different lengths of fence.
- Begrudgingly keep support for serenities one markdown extension.

1 files changed, 16 insertions, 10 deletions

diff --git a/Userland/Libraries/LibMarkdown/CodeBlock.cpp b/Userland/Libraries/LibMarkdown/CodeBlock.cpp
index 53e8e420f5..a59a15a2aa 100644
--- a/Userland/Libraries/LibMarkdown/CodeBlock.cpp
+++ b/Userland/Libraries/LibMarkdown/CodeBlock.cpp
@@ -75,9 +75,8 @@ RecursionDecision CodeBlock::walk(Visitor& visitor) const
     return RecursionDecision::Continue;
 }
 
-static Regex<ECMA262> style_spec_re("\\s*([\\*_]*)\\s*([^\\*_\\s]*).*");
-
-static constexpr auto tick_tick_tick = "```";
+static Regex<ECMA262> open_fence_re("^ {0,3}(([\\`\\~])\\2{2,})\\s*([\\*_]*)\\s*([^\\*_\\s]*).*$");
+static Regex<ECMA262> close_fence_re("^ {0,3}(([\\`\\~])\\2{2,})\\s*$");
 
 static Optional<int> line_block_prefix(StringView const& line)
 {
@@ -111,7 +110,7 @@ OwnPtr<CodeBlock> CodeBlock::parse(LineIterator& lines)
         return {};
 
     StringView line = *lines;
-    if (line.starts_with(tick_tick_tick))
+    if (open_fence_re.match(line).success)
         return parse_backticks(lines);
 
     if (line_block_prefix(line).has_value())
@@ -135,10 +134,11 @@ OwnPtr<CodeBlock> CodeBlock::parse_backticks(LineIterator& lines)
     // The code block will be made bold,
     // and if possible syntax-highlighted
     // as appropriate for a shell script.
-    StringView style_spec = line.substring_view(3, line.length() - 3);
-    auto matches = style_spec_re.match(style_spec);
-    auto style = matches.capture_group_matches[0][0].view.string_view();
-    auto language = matches.capture_group_matches[0][1].view.string_view();
+
+    auto matches = open_fence_re.match(line).capture_group_matches[0];
+    auto fence = matches[0].view.string_view();
+    auto style = matches[2].view.string_view();
+    auto language = matches[3].view.string_view();
 
     ++lines;
 
@@ -150,8 +150,14 @@ OwnPtr<CodeBlock> CodeBlock::parse_backticks(LineIterator& lines)
             break;
         line = *lines;
         ++lines;
-        if (line == tick_tick_tick)
-            break;
+
+        auto close_match = close_fence_re.match(line);
+        if (close_match.success) {
+            auto close_fence = close_match.capture_group_matches[0][0].view.string_view();
+            if (close_fence[0] == fence[0] && close_fence.length() >= fence.length())
+                break;
+        }
+
         if (!first)
             builder.append('\n');
         builder.append(line);