Regex engines

[Mo]

Andrew Kuchling wrote:
> 
> [Posted only to c.l.tcl and comp.lang.python; comp.lang.perl doesn't exist.]
> 
> Paul Duffin <pduffin at hursley.ibm.com> writes:
> > front end to a C++ program. Note that is Tcl, not Tk. And someone posted
> > don't use Tcl, use Python because it has a Tk binding and "Tcl is crap".
> 
> Ummm... If you mean the thread "C++ and Tcl", that person was writing
> about Perl, not Python.
> 
> > I would love to see (and this is not my idea) all of our communities
> > working together to produce really simple building blocks which can be
> > used by all of us. e.g.
> >       Regular expression engine.
> 
> Unfortunately all the regex engines seem inextricably tied in to their
> respective languages.
> 
> * Python 1.5 uses a hacked version of PCRE, which is a very
> good library, but it doesn't handle Unicode, though its author has said
> he's thinking about adding UTF-8 support.  I think PHP and some Scheme
> interpreters also have bindings for PCRE.
> 
> * Python 1.6 will use a new regex engine called SRE to handle both
> 8-bit and UTF-16 strings; the compiler is still written in Python at
> this point, though the engine itself is in C.
> 
> * Perl 5's regex engine is unreadable code, and disentangling it from
> the rest of Perl seems impossible.
> 
> * Tcl uses a Unicode-aware engine written by Henry Spencer, but it's
> not available as a standalone library.  At the Ottawa Linux conference
> last July I asked about releasing it, but have seen no sign of it
> almost a year later.
> 
> * Ruby seems to use a modified version of one of the GNU regex
> libraries; I can't tell if it's GNU rx or regex.
> 
> Unifying this situation seems impossible; maybe when SRE's compiler is
> translated to C, or if Spencer's library is released in a standalone
> version...


Did you know that there is a standalone version of henry's regexp
engine ported to Java? It is included in the Jacl interp (Tcl in Java),
but it is just a package, so you should be able to use it anywhere.
In fact, it is just two file Regexp.java and Regsub.java. You should
check it out.

Mo DeJong
Red Hat Inc