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Bug 2732 - Non-capturing subexpressions
Summary: Non-capturing subexpressions
Status: CLOSED WONTFIX
Alias: None
Product: XPath / XQuery / XSLT
Classification: Unclassified
Component: Functions and Operators 1.0 (show other bugs)
Version: Candidate Recommendation
Hardware: PC Windows XP
: P2 normal
Target Milestone: ---
Assignee: Ashok Malhotra
QA Contact: Mailing list for public feedback on specs from XSL and XML Query WGs
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2006-01-20 16:22 UTC by Ashok Malhotra
Modified: 2007-02-25 23:27 UTC (History)
1 user (show)

See Also:


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Description Ashok Malhotra 2006-01-20 16:22:24 UTC
Opened: 2006-01-15 19:30

http://www.w3.org/TR/2005/CR-xpath-functions-20051103/ extends the semantics
of the regular expressions defined in XML Schema 1.0 to allow for capture
buffers; I would like to re-use regular expressions as de- fined in the
candidate recommendation in a DTLL-like format, but an imporant requirement is
automatic assignment of names for the captured substrings based on the index
number of the parenthesized sub-expression as defined in the technical report.

This is not feasible however with the current syntax as it does not allow
non-capturing sub-expressions, so I would have to further extend the format
which makes sharing of regular expressions and regex engines difficult. In fact,
in order to re-use regular expressions as found on many web sites and programs,
and as produced by many tools, one would first have to re-write them to fit into
this model.

I thus think the regular expression syntax should further be extended to allow
for non-capturing sub-expressions using a syntax like (?:...) as is available in
most other regular expression formats.

regards,
--
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de Weinh.
Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Comment 1 Liam R E Quin 2006-02-01 21:05:24 UTC
Thank you for your comment.  The joint XSL and Query Working Groups agreed that
yes, this could be useful, and it will be considered for a later version.

We are not easily able to add new features at this stage.

Liam (pp. XQuery + XSL Working Groups)
Comment 2 Bj 2006-03-04 23:29:00 UTC
Is comment #1 supposed to formally address this issue? I never heard of this 
response and found it only by accident. Is there publicly archived evidence 
that the Working Groups actually sent the response to me? In that case I would 
appreciate a pointer so I can figure out what's wrong with my mail setup.

The response is not acceptable to me, I did not ask whether the Working Group 
could easily make this change, but that it makes this change. As I pointed out, 
my implementation experience is that the current design is not suitable for a 
number of important use cases, and it is not clear to me that it would be 
reasonable to assume that making this change would invalidate an individuals 
review or implementation experience. Therefore, the Working Group would need to 
come up with a more technically sound response for me to withdraw the issue.
Comment 3 Michael Kay 2006-03-05 00:28:39 UTC
We normally work on the basis that if we add a comment to a bugzilla entry,
Bugzilla automatically notifies the originator that the comment has been added.

I think Liam might have been assuming you were more familiar with W3C processes
than appears to be the case. During Candidate Recommendation phase, requests for
new features and facilities stand almost no chance of acceptance in that round
of the spec, unless you can demonstrate convincing evidence that the language is
unusable or unimplementable without the change being made. Although your request
is a perfectly reasonable suggestion for useful added functionality, it clearly
doesn't fall into that category.

Michael Kay
(personal response)
Comment 4 Andrew Eisenberg 2006-03-07 17:28:20 UTC
(In reply to comment #2)
> Is comment #1 supposed to formally address this issue? I never heard of this 
> response and found it only by accident. Is there publicly archived evidence 
> that the Working Groups actually sent the response to me? In that case I would 
> appreciate a pointer so I can figure out what's wrong with my mail setup.

Apologies. This bugzilla entry was made on your behalf, but Ashok missed adding you to the cc list. I have done so, so you should be apprised of any further discussion of this issue.
Comment 5 Ashok Malhotra 2006-03-08 13:55:24 UTC
The joint WGs discussed your request on the March 7 telcon.
It was pointed out that you had not made this request on earlier
versions of the documents.  Also, it requests new functionality that
is not germane to the languages we are standardizing.

If you wish, we can consider the requested functionality for the
next version of these languages.

Please let us know if this is satisfactory.
Comment 6 Jim Melton 2007-02-25 23:27:53 UTC
Closing bug because commenter has not objected to the resolution posted and more than two weeks have passed.