[pcre-dev] [Bug 1916] Advanced data processing for an altern…

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Old-Topics: [pcre-dev] [Bug 1916] New: Advanced data processing for an alternation with a lot of key words
Subject: [pcre-dev] [Bug 1916] Advanced data processing for an alternation with a lot of key words
https://bugs.exim.org/show_bug.cgi?id=1916

--- Comment #13 from Philip Hazel <ph10@???> ---
(In reply to Markus Elfring from comment #12)
> (In reply to Philip Hazel from comment #11)
>
> I would appreciate a bit more background information.
> http://vcs.pcre.org/pcre2/code/trunk/HACKING?revision=606&view=markup#l618
>
> * To which data structures are non-capturing brackets mapped after
> compilation by the current regular expression engine?



$ ./pcre2test -b
PCRE2 version 10.23-RC1 2016-08-01
re> /(?:abc|def|ghi)/

------------------------------------------------------------------
  0  33 Bra
  3   9 Bra
  6     abc
 12   9 Alt
 15     def
 21   9 Alt
 24     ghi
 30  27 Ket
 33  33 Ket
 36     End
------------------------------------------------------------------

data>


> * Can their evaluation be optimised any further for my use case?


I doubt it. As I said before, a generalized regex engine is a very inefficient
way of searching for lots of fixed strings. It would probably be faster just
doing something simple such as sorting your strings into alphabetical order and
then generating a 1-level or 2-level index.

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