From: "Andreas Röhler" <andreas.roehler@easy-emacs.de>
To: npostavs@gmail.com
Cc: 35708@debbugs.gnu.org
Subject: bug#35708: [27.0.50]: thingatpt.el, thing-at-point-looking-at redundant
Date: Wed, 15 May 2019 08:59:19 +0200 [thread overview]
Message-ID: <6bf2ad95-5a41-cbf1-c5ea-07dc06d0f9a1@easy-emacs.de> (raw)
In-Reply-To: <85tvdxw1dc.fsf@gmail.com>
Am 14.05.19 um 16:34 schrieb npostavs@gmail.com:
> Andreas Röhler <andreas.roehler@easy-emacs.de> writes:
>
>>> Hmm, current thing-at-point-looking-at might be slow with large
>>> buffers. The slightly modified test should reveal it:
>>>
>>> (ert-deftest thing-at-point-looking-at-2 ()
>>> (with-temp-buffer
>>> (insert "1abcd 222abcd")
>>> (dotimes (_ 99999) (insert " asdf "))
>>> (goto-char (point-min))
>>> (search-forward "2ab")
>>> (should (thing-at-point-looking-at "2abcd"))
> Yes, in this case, since the loop over looking-at only needs to iterate
> twice, so it will be faster. But what about when there is no match?
> E.g.,
>
> (with-temp-buffer
> (dotimes (_ 99999) (insert " asdf "))
> (goto-char (point-max))
> (list :ar-regexp-atpt (benchmark-run (ar-regexp-atpt "foo"))
> :thing-at-point-looking-at (benchmark-run (thing-at-point-looking-at "foo"))))
>
>> Another fix, as a bug showed up when testing (ar-regexp-atpt "[a-z]+"):
>>
>> (defun ar-regexp-atpt (regexp)
>> "Return t if REGEXP matches at or before point, nil otherwise.
>>
>> Changes match-data"
>> (save-excursion
>> (if (looking-at regexp)
>> (while
>> (and (not (bobp))
>> (or (progn (backward-char) (looking-at regexp))
>> (forward-char 1))))
>> (while (not (or (bobp) (backward-char) (looking-at regexp))))
>> (ar-regexp-atpt regexp))
> What's this recursive call for? It triggers (error "Lisp nesting
> exceeds ‘max-lisp-eval-depth’") in the benchmark above.
>
>> (looking-at regexp)))
The recursive call needed a guard: (unless (bobp)
It is called after function went backward while not looking-at matches,
Now the result for the 99999 is
(:ar-regexp-atpt (0.774574453 0 0.0) :thing-at-point-looking-at
(0.000798669 0 0.0))
The fixed form:
(defun ar-regexp-atpt (regexp)
"Return t if REGEXP matches at or before point, nil otherwise.
Changes match-data"
(save-excursion
(if (looking-at regexp)
(while
(and (not (bobp))
(or (progn (backward-char) (looking-at regexp))
(forward-char 1))))
(while (not (or (bobp) (backward-char) (looking-at regexp))))
(unless (bobp) (ar-regexp-atpt regexp)))
(looking-at regexp)))
next prev parent reply other threads:[~2019-05-15 6:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-13 7:19 bug#35708: [27.0.50]: thingatpt.el, thing-at-point-looking-at redundant Andreas Röhler
2019-05-13 12:41 ` Noam Postavsky
2019-05-13 18:31 ` Andreas Röhler
2019-05-13 19:25 ` npostavs
2019-05-14 10:02 ` Andreas Röhler
2019-05-14 10:49 ` Andreas Röhler
2019-05-14 14:34 ` npostavs
2019-05-15 6:59 ` Andreas Röhler [this message]
2019-05-15 10:11 ` Andreas Röhler
2019-05-20 17:17 ` Noam Postavsky
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