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bug#36444: [PATCH] Improved regexp-opt KEEP-ORDER check
From: |
Mattias Engdegård |
Subject: |
bug#36444: [PATCH] Improved regexp-opt KEEP-ORDER check |
Date: |
Thu, 4 Jul 2019 13:52:31 +0200 |
3 juli 2019 kl. 21.29 skrev Noam Postavsky <npostavs@gmail.com>:
>
> You don't actually need this save-match-data, right? Because there is
> already one at the top level of the function (which I'm also not sure is
> really needed, but probably best not to touch that).
Thank you! I don't know how I missed the existing save-match-data. Removed.
> IMO, a dolist + catch & throw would be a bit more readable; it took me
> some puzzling to realize that the early exit was the "non-optimized"
> case.
>
> (and keep-order
> (let* ((case-fold-search nil)
> (alts (mapconcat #'regexp-quote strings "\\|")))
> (and (catch 'has-prefix
> (dolist (s strings)
> (unless (and (string-match alts s)
> (= (match-end 0) (length s)))
> (throw 'has-prefix s))))
> (concat (or open "\\(?:") alts "\\)"))))
Not too fond of that either, really; catch/throw somehow seems more heavyweight
than warranted by the situation.
Initially I used cl-every, but ran into the usual bootstrap problems.
Here are two alternatives:
(1) Same as before, but with a comment about what tripped you up:
> (and (let ((s strings))
> (while (and s
> (string-match alts (car s))
> (= (match-end 0) (length (car s))))
> (setq s (cdr s)))
> ;; If we exited early, we found evidence that
> ;; regexp-opt-group cannot be used.
> s)
> (concat (or open "\\(?:") alts "\\)")))))
(2) Using cl-loop:
> (and (not (cl-loop
> for s in strings
> always (and (string-match alts s)
> (= (match-end 0) (length s)))))
> (concat (or open "\\(?:") alts "\\)")))))