Re: Back references inside character classes

On 02/01/2011 17:01, Paul J. Lucas wrote:
> The W3C test K2-MatchesFunc-11:
>
> 	matches("abcd", "(asd)[\1]")
>
> tests that an XQuery implementation should raise the FORX0002 error for a back reference inside a character class.  However, after reading:
>
> * XQuery and XPath Functions and Operators, section 7.6.1
> * XML Schema Part 2, appendix F
>
> I can't find where any specification explicitly forbids it.  Can somebody point me to the section of a specification that does?  Thanks.
>
It's stated twice in section 7.6.1 
(http://www.w3.org/TR/xpath-functions/#regex-syntax):

(a) "Back-references are allowed outside a character class expression."

(b) Note: Within a character class expression, \ followed by a digit is 
invalid. Some other regular expression languages interpret this as an 
octal character reference.

Michael Kay
Saxonica

Received on Sunday, 2 January 2011 19:57:03 UTC