(lisp-font-lock-keywords-2): Do \\) only in strings, because (eq ... ?\\) is fairly frequent.

1 files changed, 9 insertions, 3 deletions

diff --git a/lisp/font-lock.el b/lisp/font-lock.el
index ee1fc1a515e..ba42412d8da 100644
--- a/lisp/font-lock.el
+++ b/lisp/font-lock.el
@@ -2053,9 +2053,15 @@ This function could be MATCHER in a MATCH-ANCHORED `font-lock-keywords' item."
        ("\\<:\\sw+\\>" 0 font-lock-builtin-face)
        ;; ELisp and CLisp `&' keywords as types.
        ("\\&\\sw+\\>" . font-lock-type-face)
-       ;; Make regexp grouping constructs bold, so they stand out.
-       ("\\([\\][\\]\\)\\([(|)]\\)\\(\\?:\\)?"
-        (1 font-lock-comment-face prepend)
+       ;; Make regexp grouping constructs bold, so they stand out, but only in strings.
+       ((lambda (bound)
+          (if (re-search-forward "\\([\\][\\]\\)\\([(|)]\\)\\(\\?:\\)?" bound)
+               (let ((face (get-text-property (1- (point)) 'face)))
+                 (if (listp face)
+                     (memq 'font-lock-string-face face)
+                   (eq 'font-lock-string-face face)))))
+        (1 font-lock-comment-face prepend) ; Should we introduce a lowlight face for this?
+                                        ; Ideally that would retain the color, dimmed 50%.
         (2 'bold prepend)
         (3 font-lock-type-face prepend t))
        ;; Underline innermost grouping, so that you can more easily see what belongs together.