[DFDL-WG] Clarification needed: regular expressions - does '.' match newlines by default?
Suman Kalia
kalia at ca.ibm.com
Wed Nov 14 12:59:29 EST 2012
I came across this issue couple of weeks ago.. the regular expression
syntax used in XML Schema is strict than what is supported in Java regular
expression. DFDL regular expression syntax and restrictions should match
XML schema specification..
Here is an example for which APAR has been opened and we will supplying
fix in WMB toolkit to make regular expression comply to the XML Schema
spec...
The following line causes the XML schema compiler to fail -
<xsd:pattern value="([a-zA-Z0-9 ]|\-|\.|_|\(|\)|\\|\/|.&|\')*"/>
Here the customer has escaped forward slash and single quote characters.
Instead of \/ it should be / and instead of \' it should be '
Following is accepted by XML Schema compiler..
<xsd:pattern value="([a-zA-Z0-9 ]|\-|\.|_|\(|\)|\\|/|.&|')*"/>
Suman Kalia
IBM Canada Lab
WMB Toolkit Architect and Development Lead
Tel: 905-413-3923 T/L 313-3923
Email: kalia at ca.ibm.com
For info on Message broker
http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.html
From: Mike Beckerle <mbeckerle.dfdl at gmail.com>
To: Tim Kimber <KIMBERT at uk.ibm.com>,
Cc: dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org
Date: 11/14/2012 12:46 PM
Subject: Re: [DFDL-WG] Clarification needed: regular expressions -
does '.' match newlines by default?
Sent by: dfdl-wg-bounces at ogf.org
I agree with Tim's opinion, but add that this is *NOT* the default
behavior of the java regex library we're using in Daffodil currently. One
must prefix all regex's by (?s) I believe to achieve the non-default
line-ending behavior.
On Wed, Nov 14, 2012 at 11:15 AM, Tim Kimber <KIMBERT at uk.ibm.com> wrote:
I would vote for this feature to be switched off by default in DFDL
processors. It is mainly useful when dealing with lines of text, but DFDL
formats are not always lines of text.
So to be 100% clear, I think the '.' wildcard should match all characters,
including line endings.
regards,
Tim Kimber, DFDL Team,
Hursley, UK
Internet: kimbert at uk.ibm.com
Tel. 01962-816742
Internal tel. 37246742
From: Mike Beckerle <mbeckerle.dfdl at gmail.com>
To: dfdl-wg at ogf.org,
Date: 14/11/2012 12:53
Subject: [DFDL-WG] Clarification needed: regular expressions - does
'.' match newlines by default?
Sent by: dfdl-wg-bounces at ogf.org
A key behavior distinction in regular expressions is whether the '.'
wildcard matches line endings or not.
Regular expression libraries can be configured, usually by some sort of
expression modifier, either way so that the '.' will not match a line
ending or so that it will.
Question is, how is it configured by default in DFDL regular expressions?
This is part of the overall issue of tightening up regular expressions as
part of DFDL. I.e., what exactly is the regex dialect, and how is it
configured by default.
...mike
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Mike Beckerle | OGF DFDL WG Co-Chair
Tel: 781-330-0412
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