[xml] contains() argument treated like XPath expression

[Larry Siden <lsiden-public comcast net>]

I looked in the code for the "contains(string)" function the other day 
and noticed that its argument is handed off to another routine that 
parses it as if it were an XPath expression.  Since contains() is used 
for string searches, wouldn't it be better to parse its argument as a 
regular expression?  I haven't taken the time to research it, but I'll 
bet there's a number of open source regular-expression libraries that 
can parse and search for the expression.  At the very least, I would 
expect the argument to be treated as a literal string with special 
character sequences, like '\n', recognized so that it is possible to 
search for an end-of-line, for example.  If anyone is interested in 
this, and Daniel V. grants his blessing, I will volunteer to look into 
doing it, because this feature might have helped me on one of my projects.

-Larry Siden