Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!husc6!cmcl2!rna!amms4!hjg
From: hjg@amms4.UUCP (Harry Gross)
Newsgroups: comp.os.minix
Subject: Re: A full, V7-Compatible expr(1)
Message-ID: <600@amms4.UUCP>
Date: 25 Jul 89 19:50:10 GMT
References: <13618@ea.ecn.purdue.edu> <2898@yunexus.UUCP>
Reply-To: hjg@amms4.UUCP (Harry Gross)
Organization: Eagle Clothes, Inc., New York, NY
Lines: 38

In article <2898@yunexus.UUCP> oz@yunexus.UUCP (Ozan Yigit) writes:
>In article <13618@ea.ecn.purdue.edu> housel@en.ecn.purdue.edu (Peter S. Housel) writes:
>>	The regular expression code is my own, as it was not possible
>>to use any of the commonly available regular expression matching
>>libraries.  (expr(1) uses the ed(1) regexp syntax, while the libraries
>>implement extensions or improvements.
>
>Hmmm ? My implementation of bsd-clone regexp (pd) library would have saved
>you a lot of time, as its "extensions" are but minor, and it would have
>been trivial to zap them (5 minutes). Rest behaves as expected... Ah welll...

Oddly enough, I just started to work on this problem myself.  I wanted to run
the Configure script that comes with 'patch', and got bitten by the lack of
the ':' operator in the MINIX version of 'expr'.  A slightly closer look
revealed that MINIX 'expr' doesn't handle any strings at all.

I decided that I would try my hand at fixing it.  Most of the modificatons
appear to be fairly minor (with the exception of R.E. analysis :-) and I have
completed much of it already.  Since MINIX is supposed to be a V7 look-alike
(sorta :-) I plan to extract the V7 'ed' definition of a R.E. and incorporate
that into my version of 'expr' (as per V7 'expr' and 'ed' documentation).

If someone has posted diffs for 'expr' already (or a replacement for it), please
let me know (by email, preferably), and I will keep my work to myself (unless
there is a great demand to see it :-).  If I haven't heard from anyone by the
time I finish, I will post my diffs to the net.

By the way, yes I do have a copy of (some - not all) of the V7 documentation, as
that was the first UNIX system I used (back in 1977, at Duke University, right
around the time Tom Truscott was inventing this thing we call Usenet :-).  This
documentation is what I am using as a guidepost to how things should behave.

Cheers,
-- 
		Harry Gross				 |  reserved for
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