Re: [xml-dev] Nasty XPath expressions

From
bob mcwhirter <>
To
Kelvin Yeow <>
Date
2001-12-13T13:49:50Z
ID
<>
Thread
Re: [xml-dev] Nasty XPath expressions
On Thu, 13 Dec 2001, Kelvin Yeow wrote:

> I wonder what XPath expressions would cause an "XPath processor" to sweat?
> Any "XPath processor" developer out there?

Howdy, I'm Bob, one of the developers of Jaxen (http://jaxen.org/), a
'universal' XPath engine for Java.

The biggest issue we've had (it's Today's Big Issue) is regarding 
document-ordering when using a union expression.

	$foo/bar | $cheese/melty

XPath says that nodes should be returned in 'document order', which
becomes a non-trivial in the case of some expressions involving
the union operator.  One developer has a solution, but it is of
O(tree-size) complexity.  Do that against a 30mb document, and
suddenly XPath isn't nearly as attractive.

Long/complex xpaths, or xpaths involving '//' and such aren't really
that hairy.

	-bob