From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21724 invoked by alias); 4 Jul 2013 07:51:33 -0000 Mailing-List: contact glibc-bugs-regex-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-regex-owner@sourceware.org Received: (qmail 21687 invoked by uid 55); 4 Jul 2013 07:51:29 -0000 From: "bugdal at aerifal dot cx" To: glibc-bugs-regex@sourceware.org Subject: [Bug regex/52] Repeated and nested subexpressions (reproducible in most other engines) Date: Thu, 04 Jul 2013 07:51:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: regex X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: minor X-Bugzilla-Who: bugdal at aerifal dot cx X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: gotom at debian dot or.jp X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2013-07/txt/msg00007.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=52 --- Comment #14 from Rich Felker --- On Thu, Jul 04, 2013 at 07:42:51AM +0000, bonzini at gnu dot org wrote: > Unices. Also, even though it is not POSIX RE, Perl regular expressions have > the same behavior. Perl RE's are so different from POSIX that I would not consider them in this discussion. > Thanks for mentioning musl's matcher, I'll check it out. The upstream source we got it from, TRE, is where the magic came from. The author has some good documentation on how it works. > Matching backreferences at a decent speed _and_ obeying the POSIX > leftmost/longest rules is very hard to do. Currently the speed is somewhat less than glibc, but not horrible by any means. A large part of the cost is probably mbtowc. I'm planning to eventually adapt it to compile the UTF-8 RE directly to a byte-based state machine with actual character identity decoding only when matching against character classes, but it's low priority right now. -- You are receiving this mail because: You are on the CC list for the bug.