NetNews Usenet Archive 1992 #26/NN_1992_26.iso/spool/comp/lang/perl/6904

Text File | 1992-11-09 | 1.9 KB | 41 lines

Newsgroups: comp.lang.perl
Path: sparky!uunet!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!ux1.cso.uiuc.edu!news.cso.uiuc.edu!chappell
From: [e-mail] (Glenn Chappell)
Subject: Partial RegExp's
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Reply-To: [e-mail] (Glenn Chappell)
Organization: Math Dept., University of Illinois at Urbana/Champaign
Date: Mon, 9 Nov 1992 15:11:20 GMT
Lines: 29

Here's a question I've been pondering for a few weeks:

Inherent in the design of Perl seems to be the idea that you always have
enough space in memory for the entirety of any file you'd ever want to
work on. But what if you don't? How does one do wonderful things like
"split" and various pattern matches & such on files that are just too big?

Well, if there's already a standard, ok-I'll-spell-it-all-out-for-a-
neophyte-like-you-but-next-time-read-the-book-okay answer to this
question, I'd like to hear it. If, not, an idea:

Of course, the way you deal with huge files is to read them in chunks.
The problem with that is that you miss a pattern match that starts on
one chunk and ends on another.

Currently, the result of an attempt at a pattern match gives one of two
responses: "Got a match" or "Didn't get a match". What if there were a
way to tell the pattern matcher that some patterns may extend off the
end of the currently available text, and we gave the matcher the ability
to give two other reponses: "Got a partial match, and if you give me
more data, I may get a match" and "Got a match, which may turn into a
bigger match if you give me more data". The matcher would also return
the place at which the partial match began.

Now, from what I know of pattern matching, it seems to me that this would
be an easy modification to do. The question, then, is whether it would
be worthwhile. So, does anyone think so? Or is it just me?

                Glenn Chappell  <><