From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Drew Adams <drew.adams@oracle.com>
Cc: "help-gnu-emacs@gnu.org" <help-gnu-emacs@gnu.org>
Subject: Re: [External] : Re: Performance of `re-search-backward' vs `re-search-forward'
Date: Mon, 12 Apr 2021 17:03:19 -0400 [thread overview]
Message-ID: <jwv7dl7b4lb.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <SA2PR10MB4474587E68403400BF0EBE10F3709@SA2PR10MB4474.namprd10.prod.outlook.com> (Drew Adams's message of "Mon, 12 Apr 2021 20:40:36 +0000")
>> So both basically move character by character and check if the regex
>> matches there (more or less)?
> They don't move character by character.
> They use the Boyer-Moore search algorithm.
> https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string-search_algorithm
While this is true in the special case where your regexp only matches
a constant string (i.e. you could have used the non-re
`search-(for|back)ward` instead), it's a rare exception. In the vast
majority of cases it does move character by character.
Stefan
next prev parent reply other threads:[~2021-04-12 21:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 5:38 Performance of `re-search-backward' vs `re-search-forward' Marcin Borkowski
2021-04-12 15:13 ` Stefan Monnier
2021-04-12 19:39 ` Marcin Borkowski
2021-04-12 20:40 ` [External] : " Drew Adams
2021-04-12 21:03 ` Stefan Monnier [this message]
2021-04-12 20:59 ` Stefan Monnier
2021-04-13 6:07 ` Marcin Borkowski
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