In processing text, I'm trying to convert dates of the form "January 1, 1999" or "January 1999", but I'm having trouble using captured groups. For example, I have tried to convert the dates to the form "1999-Jan" using the following:
For some reason the substring() invocation doesn't work, and I have found that to be true if I call any other function, including my kti:month-from-name() function.

I'm also confused about why I need quotes around the $3 and $4.

Ian

The reason for this is that what the replace function is actually performing is this:


<xsl:value-of select="replace(., '(January|February|March|April|May|June|July|Augus t|September|October|November|December)\s+(\d{1,2}, \s*)?(\d{4})(\D|$)', '$3-$1$4'), 'i')"/>

i.e. substring('$1', 1, 3) = '$1'
the substition is done after substring has been performed.

/- Sam Judson : Wrox Technical Editor -/

As with any function call, the arguments to replace() are simple XPath expressions and they are evaluated independently, without any special treatment given them because they appear in a replace() call. So substring('$1', 1, 3) evaluates to '$1', just as it would anywhere, and substring($1, 1, 3) is a syntax error, just as it would be anywhere.

Try doing this with xsl:analyze-string. That will allow you to use

substring(regex-group(1), 1, 3)

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Thanks Sam and Michael!

I get it now, at least when I think about it, but I'm sure I'm going to make the same mistake again :).

As you suggested Michael, I happily got it working using <analyze-string/>.

Thanks again,
Ian