Support multiple consecutive reader comments (#_#_a b)

[sulami]

Modified the default regexps and the heuristic to find the end of the region to
comment out.

Previously Emacs would treat the second #_ as the commented form, and then
highlight the following two forms as usual. Now it (mostly) matches what Clojure
actually evaluates. Things get weird when you start mixing #_ and forms, but
this fixes the most common use cases, like key-value-pairs.

Tagging #404/#528 for visibility

Note: I couldn't get the tests to work locally, so I'd be grateful if someone wants to add a test case for the above.

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Thanks!

[bbatsov]

Note: I couldn't get the tests to work locally, so I'd be grateful if someone wants to add a test case for the above.

What's the problem you had with the tests? Make test works fine for me.

[sulami]

Note: I couldn't get the tests to work locally, so I'd be grateful if someone wants to add a test case for the above.

What's the problem you had with the tests? Make test works fine for me.

make: *** No rule to make target `/Users/sulami/.emacs.d/straight/repos/clojure-mode/.cask/26.3/elpa', needed by `test'.  Stop.

[bbatsov]

What happens when you do emacs --version in a terminal?

Perhaps you can run make elpa before make test and this will work?

[sulami]

Emacs 26.3 (+ licensing info)

make elpa && make test worked fine (and passed), thanks! I'll have a look if I can craft a test for my change.

[sulami]

Okay, I've added some tests. It font-locks the second pair in #_#_ to comment if there's nothing following, which isn't strictly true in the "what the clojure reader sees" sense, but it's no like #_ by itself is valid anything anyway.

[yuhan0]

Hi, just as a point of comparison, I had my own implementation of this feature roughly as follows, which uses a "stack" in the search function to determine the discarded range instead of regex.

(defun clojure--search-comment-macro-internal (limit)
  "Search for a comment forward stopping at LIMIT."
  (when (search-forward-regexp clojure-comment-regexp limit t)
    (let* ((md (match-data))
           (start (match-beginning 1))
           (state (syntax-ppss start))
           (skip 1))
      ;; inside string or comment?
      (if (or (nth 3 state)
              (nth 4 state))
          (clojure--search-comment-macro-internal limit)
        (goto-char start)
        (save-match-data
          (while (< 0 skip)
            (if (looking-at clojure-comment-regexp)
                (progn (goto-char (match-beginning 1))
                       (incf skip))
              (clojure-forward-logical-sexp 1)
              (skip-chars-forward " \n")
              (decf skip))))
        ;; Data for (match-end 1).
        (setf (elt md 2) (elt md 0))
        (setf (elt md 3) (point))
        (set-match-data md)
        t))))

The (dubious) advantage of this is that it works when you have interleaving forms , better emulating how the clojure reader works.

However It might be much slower than this implementation which is good for 99.9% of use cases (not sure how font-lock performance could be benchmarked)

[bbatsov]

(not sure how font-lock performance could be benchmarked)

I guess you can just generate a huge Clojure buffer, start the Emacs profiler and see how much time will be spend in font-locking with both approaches.

[bbatsov]

@sulami Thanks for tackling this! Sorry about the slow turnaround.