Re: Regular expression libraries

["Clément Pit--Claudel" <clement.pit@gmail.com>]

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On 2016-12-16 10:42, Lars Ingebrigtsen wrote:
> Clément Pit--Claudel <clement.pit@gmail.com> writes:
> 
>> Wait, now I'm confused.  The master branch of glibc *does* include the following in regex.h:
>>
>> extern int __re_search_2
>>   (struct re_pattern_buffer *buffer, const char *string1,
>>    int length1, const char *string2, int length2,
>>    int start, int range, struct re_registers *regs, int stop);
>>
>> … but the implementation just allocates a large buffer and concatenates both strings?
> 
> Yes.  If I remember correctly, a glibc developer popped up here a couple
> of years ago announcing that they were going to do that change (thereby
> making __re_search_2 incredibly slow, but retained for compatibility).

I see, thanks.  This code seems a bit beyond my abilities to easily extend :/
Eli started listing things that we would need from an external library before we could move to it.  AFAICT, there is:

* Support for searching a gap buffer (essentially two strings).
* Support for Emacs' internal utf-8 based encoding
* Support for Emacs' regexp syntax (though we could imagine writing a translator)
* Support for Emacs' syntax properties, and Emacs-specific extensions like matching the position of the point, etc.

An I missing anything else? Which ones of these things does gnulib already have?

Thanks!
Clément.


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