Hi Roger,
see below:
Costello, Roger L. wrote:
Hi Folks,
Is there a complete list of processor-specific capabilities in XPath
2.0?
See the W3C spec pages, there's a full list.
Here's the list that I currently have:
1. Evaluating the range expression in an XPath "some" expression is
processor-specific.
Example: Consider this <prices> element, which is comprised of a list
of values:
<prices>40.99 19.00 N/A 23.80</prices>
And this "some" expression:
some $i in data(prices) satisfies ...
An XPath processor may:
- evaluate the list values left-to-right
- evaluate the list values right-to-left
- stop at the first list value where the satisfies expression yields a
true value
- evaluate all list values
That doesn't make the result different, that's just (possibly) about
optimization and implementation. And that's different between each and
every xpath processor.
btw, you forgot to mention: "evaluate to true immediately when it is not
a list of values and the single value is not empty or the empty list".
Furthermore, the processor may optimize the whole expression away when
it seems fit and not loop at all. For instance, when schema-aware is on
and the values you are evaluating appears to be declared as a list of
positive integers, which will always return true. Etc. But again, that
won't change the outcome, of course.
2. Evaluating the range expression in an XPath "every" expression is
processor-specific.
Example: Consider this <prices> element, which is comprised of a list
of values:
<prices>40.99 19.00 N/A 23.80</prices>
And this "every" expression:
every $i in data(prices) satisfies ...
An XPath processor may:
- evaluate the list values left-to-right
- evaluate the list values right-to-left
- stop at the first list value where the satisfies expression yields a
false value
- evaluate all list values
same as above. There's nothing processor specific here. When the spec
says something about processor specific-ness (i.e., how to resolve a URI
in a doc() function) then different processors will act differently and
then it's something to worry about. This isn't.
3. A processor that is not schema-aware will not support these
functions:
- schema-element()
- element()
- attribute()
Now you have something, this is largely different, but now you are
talking of XSLT and not of XPath, I believe. On the spec pages there's a
list of all processor specific features that's of the implementor's
discretion to choose his/her implementation and functionality.
Cheers,
-- Abel Braaksma
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