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#35708
[27.0.50]: thingatpt.el, thing-at-point-looking-at redundant
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Am 15.05.19 um 08:59 schrieb Andreas Röhler:
>
> Am 14.05.19 um 16:34 schrieb npostavs <at> gmail.com:
>> Andreas Röhler <andreas.roehler <at> 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:
>
>
Make sure match pos includes cursor pos:
(defun ar-regexp-atpt (regexp)
"Return t if REGEXP matches at or before point, nil otherwise.
Changes match-data"
(save-excursion
(let ((orig (point)))
(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)))
(and
(looking-at regexp)
(<= (match-beginning 0) orig)
(>= (match-end 0) orig)))))
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This bug report was last modified 5 years and 362 days ago.
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