I am trying to create a Regex for Imenu indexing for my CSS modes but I'm having trouble getting it exactly right as I'm no regular expression guru. Here's a snippet of LESS CSS I'm using (regexp-builder) to test against:

@font-face {
  font-family: 'sorts_mill_goudyregular';
  src: url('/webfonts/GoudyStM-webfont.eot');
  font-weight: normal;
  font-style: normal;

body {
  margin: 0;
  padding: 0;

#foo {
  color: blue;

.CheltenhamBT-BoldHeadline {
  font-family: CheltenhamBT-BoldHeadline;
  font-weight: normal;
  font-style: normal;

.ClarendonText-Bold {
  font-family: ClarendonText-Bold;
  font-weight: normal;
  font-style: normal;
  .bold {
    font-weight: bold;

Given this, I would like the menu to contain the following entries:

  • @font-face
  • body
  • #foo
  • h1, h2, h3, .CheltenhamBT-BoldHeadline
  • .ClarendonText-Bold

Note, I'm not interested in the nested .bold declaration.

I've tried a few approaches and have it mainly working, but I'm having trouble accounting for the occasional ,\n. Here's my current regex:


Can anyone help me out?

  • Wouldn't something like "^[^{]+{" work? (It probably will, if you always put the open curly brace on the same line with selector, but if you will ever decide to move it to the next line, then, I'm afraid, regexp won't do it at all).
    – wvxvw
    Mar 18, 2015 at 16:36

1 Answer 1


You don't have to create a one-liner. The following list of definitions should create an imenu items:

(setq less-imenu-generic-expression
      '((nil "\\(^@font-face\\)" 1)
        (nil "\\(^body\\)" 1)
        (nil "\\(^#foo\\)" 1)
        (nil "\\(^h[123]\\)" 1)
        (nil "\\(^\.CheltenhamBT-BoldHeadline\\)" 1)
        (nil "\\(^.ClarendonText-Bold\\)" 1)))
(add-hook 'css-mode-hook 
          (lambda ()
            (setq imenu-generic-expression less-imenu-generic-expression)))

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