Re: [htdig3-dev] Regex


Gilles Detillieux (grdetil@scrc.umanitoba.ca)
Wed, 5 May 1999 12:36:41 -0500 (CDT)


According to Geoff Hutchison:
> >so that may change the user's expectations. Also, economy of syntax
> >is more important in a search dialog than in a configuration file.
> >My feeling is that for the regex fuzzy algorithm, an anchored match by
> >default may make more sense. For an unanchored match, you can add ".*"
> >before or after the pattern.
>
> I'd still like to see if we can figure out a nice way to allow searches for
> those of us who can't remember how to do POSIX-style regex. People have
> asked for searches like "gdbm*" or "ho?se" and can be done with regexp.
> Should we just divide these into "naive" and "full" regexp? (I admit to
> falling into the former category.) If so, what do we allow in naive regex?
> Do we just say that a '?' really means '.?' and a '*' really means '.*'?

These are the translations you'd need for naive -> full regex:
        Naive Full
         ? .
         * .*
         \x \x
         . \.

and possibly escaping a few other special characters with "\". But,
characters within brackets should go through as-is, because I think we
want the same handling of bracketed character classes in the naive and
full parsing.

> Finally we'll need some pretty significant changes to htsearch's use of
> punctuation to get this to work properly. Remember that valid_punctuation
> by default includes a few regex control characters. :-(

Yes, this is something to consider. It also occurred to me that using
parentheses to introduce a regex in htsearch may conflict with boolean
expressions. Maybe in this context, something like /regex/ would make
more sense? Just a thought.

-- 
Gilles R. Detillieux              E-mail: <grdetil@scrc.umanitoba.ca>
Spinal Cord Research Centre       WWW:    http://www.scrc.umanitoba.ca/~grdetil
Dept. Physiology, U. of Manitoba  Phone:  (204)789-3766
Winnipeg, MB  R3E 3J7  (Canada)   Fax:    (204)789-3930
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