[xsl] regex and tab-delimited text

[Terry Ofner <tofner@xxxxxxxxxxx>]

Forgive me if this topic has already been discussed. My query has to  
do with the lack of the \t construct in regular expressions.

I will preface my remarks by saying that I am used to using the grep  
patters in BBEdit on a Mac. As a matter of course, I regularly use \t  
to select or insert a tab character. In the various places I looked,  
(XSLT 2.0: Programmer's Reference, and google searches), I could find  
no examples for parsing tab-delimited text files. I finally decided  
to replace \s with the escape sequence for the tab (	). When I  
edited my stylesheet I made an error. I left the <<\>> in, creating  
this escape sequence: \&#09;

<xsl:analyze-string select="$in" regex="\&#09;A&#09;(.*)&#10;">

Saxon8 produced this error message:

 XTDE1140: Error in regular expression:  
net.sf.saxon.trans.DynamicError: Error at character
  1 in regular expression "\\tA\t(.*)\n": invalid escape sequence

I removed the offending <<\>> and the transformation worked as  
advertised.

My question has to do with the fact that \t does not seem to work in  
the stylesheet, but Saxon uses \t to report the error. I understand  
that the regular expressions used by XSLT 2.0 are dictated by XPath  
2.0, so perhaps this is out of Saxon's hands. I was just wondering  
why the construct is not available.

Terry