Fix highlighting of deleted lines in diffs.

1 files changed, 24 insertions, 0 deletions

diff --git a/config/initializers/rouge_diff_lexer.rb b/config/initializers/rouge_diff_lexer.rb
new file mode 100644
index 00000000000..fdb2d7b748e
--- /dev/null
+++ b/config/initializers/rouge_diff_lexer.rb
@@ -0,0 +1,24 @@
+# Here until https://github.com/jneen/rouge/pull/297 is merged into Rouge and the gem is updated in GitLab.
+module Rouge
+  module Lexers
+    class Diff
+      def self.analyze_text(text)
+        return 1   if text.start_with?('Index: ')
+        return 1   if text.start_with?('diff ')
+        return 0.9 if text.start_with?('--- ')
+      end
+
+      state :root do
+        rule(/^ .*\n/, Text)
+        rule(/^---\n/, Text)
+        rule(/^\+.*\n/, Generic::Inserted)
+        rule(/^-+.*\n/, Generic::Deleted)
+        rule(/^!.*\n/, Generic::Strong)
+        rule(/^@.*\n/, Generic::Subheading)
+        rule(/^([Ii]ndex|diff).*\n/, Generic::Heading)
+        rule(/^=.*\n/, Generic::Heading)
+        rule(/.*\n/, Text)
+      end
+    end
+  end
+end