From 9358b1cdd5f13e6638030446880f731785ca38f1 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <git@lukegb.com>
Date: Thu, 2 Jul 2020 23:02:43 +0100
Subject: [PATCH 3/6] Syntax highlight rules.pl

---
 .../diff/gr-syntax-layer/gr-syntax-layer.ts         | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.ts b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.ts
index 0c3bb40ce4..ace253da30 100644
--- a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.ts
+++ b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.ts
@@ -109,6 +109,10 @@ const LANGUAGE_MAP = new Map<string, string>([
 ]);
 const ASYNC_DELAY = 10;
 
+const FILENAME_OVERRIDES = new Map<string, string>([
+  ['rules.pl', 'prolog'],
+]);
+
 const CLASS_SAFELIST = new Set<string>([
   'gr-diff gr-syntax gr-syntax-attr',
   'gr-diff gr-syntax gr-syntax-attribute',
@@ -258,10 +262,17 @@ export class GrSyntaxLayer
     }
   }
 
+  _basename(filename: string): string {
+    const pieces = filename.split(/\//);
+    return pieces[pieces.length-1];
+  }
+
   _getLanguage(metaInfo: DiffFileMetaInfo) {
     // The Gerrit API provides only content-type, but for other users of
     // gr-diff it may be more convenient to specify the language directly.
-    return metaInfo.language ?? LANGUAGE_MAP.get(metaInfo.content_type);
+    return metaInfo.language ?? 
+        FILENAME_OVERRIDES.get(this._basename(metaInfo.name)) ??
+        LANGUAGE_MAP.get(metaInfo.content_type);
   }
 
   /**
-- 
2.29.2