Re: [PATCH] Interpret :/<pattern> as a regular expression

From: Jeff King <peff@peff.net>
Date: Jun 13, 2007, 20:00 UTC
Message-ID: <20070613200011.GA17360@coredump.intra.peff.net>
In-Reply-To: <Pine.LNX.4.64.0706131953370.4059@racer.site>

On Wed, Jun 13, 2007 at 07:54:59PM +0100, Johannes Schindelin wrote:

> :-) Since you seem comfortable with regular expressions, maybe you can 
> help me: I am looking for a pattern which matches _any_ character, and one 
> which matches only non-newlines, both with and without REG_NEWLINE. Hmm?

Without REG_NEWLINE, any character is just '.', but I think you are stuck with '[^ ]' for non-newlines, since POSIX makes no provisions for quoting the newline (I just skimmed through POSIX chapter 9, and I didn't see anything useful).

With REG_NEWLINE, non-newlines is of course '.'. Matching both is tricky without using extended regular expressions (where you could just do '.| '). In fact, I have been playing with it for a few minutes and I can't seem to find a good way, since you really want to represent '.' _inside_ a bracketed alternation sequence. But I don't think there's a character class for "everything".

I think this would be much easier with pcre, but ISTR some opposition to that a few months back.

So that's probably not very helpful to you, but at least you have confirmation from one other person that the answer isn't totally obvious. :)

-Peff