Date: 07 Jul 1999 21:31:10 +0200 From: Dag-Erling Smorgrav <des@flood.ping.uio.no> To: Jamie Howard <howardjp@wam.umd.edu> Cc: Archie Cobbs <archie@whistle.com>, freebsd-hackers@FreeBSD.ORG, tech-userlevel@netbsd.org, tech@openbsd.org Subject: Re: Repalcement for grep(1) Message-ID: <xzpzp18s1dt.fsf@flood.ping.uio.no> In-Reply-To: Jamie Howard's message of "Sun, 4 Jul 1999 21:32:22 -0400 (EDT)" References: <Pine.GSO.4.10.9907042126350.23842-100000@rac9.wam.umd.edu>
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Jamie Howard <howardjp@wam.umd.edu> writes: > On Sun, 4 Jul 1999, Archie Cobbs wrote: > > There are two special cases- of bracket expressions: the > > bracket expressions `[[:<:]]' and `[[:>:]]' match the null > > string at the beginning and end of a word respectively. > > Perhaps this will help with -w? > Yes, I received a patch from Simon Burge which implements this. It also > beats using [^A-Za-z] and [A-Za-z$] as I was and GNU grep does. No, because there are scripts out there (e.g. ports/Mk/bsd.port.mk) which rely on this behaviour. I suggest you explore the magic of the nmatch and pmatch arguments to regexec() :) Specifically, the pattern matched a word if: ((pmatch[0].rm_so == 0 || !isalpha(line[pmatch[0].rm_so-1])) && (pmatch[0].rm_eo == len || !isalpha(line[pmatch[0].rm_eo]))) This is off the top of my head, from reading the man page: you'll have to try it out to see if it works. You might want to replace isalpha with something less restrictive, such as isalnum(), or: #define isword(x) (isalnum(x) || (x) == '_') (judging from empirical observation, the latter corresponds to what GNU grep does) As for full-line matches (-x), simply check that (pmatch[0].rm_so == 0 && pmatch[0].rm_eo == len) This should save you from playing games with back-references. (both code snippets assume that line points to a line of text from the input and that len is the length of that line minus the newline) DES -- Dag-Erling Smorgrav - des@flood.ping.uio.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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