Re: [pcre-dev] Calling pcre_dfa_exec on expressions with bac…

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Author: Zoltán Herczeg
Date:  
To: Bogdan Harjoc, pcre-dev
Subject: Re: [pcre-dev] Calling pcre_dfa_exec on expressions with backreferences
Hi,

do you know that PCRE now has an sljit based JIT compiler? Machine code runs much faster than the normal pcre_exec and there is no such restrictions such as with the DFA engine.

Regards,
Zoltan

Bogdan Harjoc <harjoc@???> írta:
>Snort uses PCRE to filter traffic through about 3200 regexes, about 300 of>

which contain backreferences and possessive quantifiers. The rest of them>
(2900) could run faster through the alternative DFA algorithm.>
>

But since pcre_dfa_exec doesn't return an error when given a pcre object>
than uses these two unsupported features, callers have to search for them>
in the expression to decide which algorithm can be applied.>
>

What would be best ? A flag (PCRE_DFA_ONLY) so pcre_compile returns an>
error if pcre_dfa_exec would not be suitable, a pcre_is_dfa(pcre *) or an>
error code from pcre_dfa_exec ?>
>

Or is there already a way to determine which algorithm to use, other than>
reading pcrematching(3) ?>
>

Thanks!>
Bogdan Harjoc>
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