Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > comp.lang.python > #45885

Re: Utility to locate errors in regular expressions

Path csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!news.stack.nl!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path <jeanpierreda@gmail.com>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.029
X-Spam-Evidence '*H*': 0.94; '*S*': 0.00; 'parser': 0.07; 'cc:addr :python-list': 0.11; 'python': 0.11; '24,': 0.16; 'appreciated!': 0.16; 'exists?': 0.16; 'expressions,': 0.16; 'failure.': 0.16; 'subject:expressions': 0.16; 'subject:regular': 0.16; 'wrote:': 0.18; 'module': 0.19; 'cc:addr:python.org': 0.22; '(or': 0.24; 'cc:2**0': 0.24; 'cc:no real name:2**0': 0.24; 'task': 0.26; 'header:In-Reply-To:1': 0.27; 'idea': 0.28; 'am,': 0.29; 'possibility': 0.29; 'message-id:@mail.gmail.com': 0.30; 'branches': 0.31; 'operators': 0.31; 'regular': 0.32; 'fri,': 0.33; 'advice': 0.35; 'received:209.85': 0.35; 'received:209.85.220': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'possible': 0.36; 'similar': 0.36; 'received:209': 0.37; 'depends': 0.38; 'skip:u 10': 0.60; 'first': 0.61; 'different': 0.65; 'regexp': 0.84; 'step,': 0.84; 'from.': 0.93; '2013': 0.98
DKIM-Signature v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=WHUftlDNR8wssXfLWDQRya4v1gZWFLWsPhPbdiv5+FM=; b=L8b4c1E2hodCWbLG/Pgw6rMc/hJcusVzJTBrEJOS/I5Une/Es1jmHo3FfFvSjtkBPJ +nBSEmonDmDqiX90H7nAUDILuTiFjuIwP2NwFTkjBKKkxjK5DCd8alaGas5hAc+pwSN1 pM8sc5M6kI8PdiFwEc25x+MNnq2vyt1+4/dX8mkuc2ywooNvbnasYEDiJubO+hhkOvOS 0WTO8Mct2Yi1sp8i6LSglvGOvLIQnsmsp6Q3HV04pJEccm5LRen3VlFmf3lnbsJtsYQn Jqmu+sWqOaowjoUJDOB+SbccEP1HrpOsR5P2SuSCRbtY+QnGn7eIhSSDl8USQoqtITR8 4qLA==
X-Received by 10.52.158.225 with SMTP id wx1mr7193663vdb.121.1369401262158; Fri, 24 May 2013 06:14:22 -0700 (PDT)
MIME-Version 1.0
In-Reply-To <knno5h$t9f$1@ger.gmane.org>
References <knno5h$t9f$1@ger.gmane.org>
From Devin Jeanpierre <jeanpierreda@gmail.com>
Date Fri, 24 May 2013 09:13:41 -0400
Subject Re: Utility to locate errors in regular expressions
To Malte Forkel <malte.forkel@berlin.de>
Content-Type text/plain; charset=UTF-8
Cc python-list@python.org
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.15
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.2065.1369401265.3114.python-list@python.org> (permalink)
Lines 16
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1369401265 news.xs4all.nl 15909 [2001:888:2000:d::a6]:34685
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:45885

Show key headers only | View raw


On Fri, May 24, 2013 at 8:58 AM, Malte Forkel <malte.forkel@berlin.de> wrote:
> As a first step, I am looking for a parser for Python regular
> expressions, or a Python regex grammar to create a parser from.

the sre_parse module is undocumented, but very usable.

> But may be my idea is flawed? Or a similar (or better) tools already
> exists? Any advice will be highly appreciated!

I think your task is made problematic by the possibility that no
single part of the regexp causes a match failure. What causes failure
depends on what branches are chosen with the |, *, +, ?, etc.
operators -- it might be a different character/subexpression for each
branch. And then there's exponentially many possible branches.

-- Devin

Back to comp.lang.python | Previous | NextNext in thread | Find similar | Unroll thread


Thread

Re: Utility to locate errors in regular expressions Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-05-24 09:13 -0400
  Re: Utility to locate errors in regular expressions Roy Smith <roy@panix.com> - 2013-05-24 09:40 -0400

csiph-web