pcre, bifs, drivers and ports

[Mats Cronqvist]

Ernie Makris wrote:
> Hello Erlangers,
> 
> One thing I wanted to start a discussion on is getting pcre style
> regexps in erlang. The question
> I pose to the list is: What would be the best way to integrate the pcre
> library into erlang.
> The possible approaches I've seen so far are:
> - create a linked in driver
> - create a port program
> - create new bifs (I'd really like this)

   a bif is the way to go, imo.

> My obvious concerns are:
> - How stable is the C pcre library for long running servers
> - Stability implies:
>     - Memory leaks
>     - SIGSEGVs
> 
> I would love the library calls in erlang to be bifs. Are there any
> external examples, aside from just looking at the source that
> demonstrate how to cleanly add a new bif?

   two weeks ago me and a colleague implemented two new bifs; re:grep/2 and 
re:compile/1.

   documentation is a bit scarce;

re:compile([RegExp]) -> [RegExpC]
re:grep(Str,[RegExp]) -> [MatchItem]
RegExp = string()
RegExpC = term()
MatchItem = no_match | {int(Beg),int(End),[string(SubMatch)]} | 
{error,{string(ErrorStr),int(ErrorChar)}}

   we have not yet observed any problems with stability.

   OTP has indicated that they will not introduce any bif that does not execute 
in bound time, or yields. i believe this can be met by limiting the length of 
the string and the regexp.

   if there is interest, we can probably make the code available.

   mats