XPath grammar

I just tried to create the BNF grammar of the streamable XPath subset as
specified during the F2F meeting. Please review carefully, since I'm not
convinced I got it right, and especially since I was rather restrictive
on what I allowed to be used within the predicates. I think there would
be several spots where additional operators or functions might be
useful, but I didn't see the grammar getting easier, hence decided to
cut them off anyway.

Also, I decided to do two separate grammars, one for IncludedXPath and
one for ExcludedXPath. The problem of merging both into one grammar is
that this would require most of the tokens to be relabeled to
"IncludedXPathFoo" and "ExcludedXPathFoo", which I already found
annoying for the "FinalStepFoo" and "NonFinalStepFoo" tokens.

After all, I'm not happy with that solution either, since the only
difference between IncludedXPath and ExcludedXPath grammar is the
"attribute" AxisName being allowed in the latter only. Hence, we have
three options here:

a) merge Included and Excluded into one grammar
b) leave as is
c) simplify the grammar even more, stating the intended differences
between Included and Excluded, or non-final step and final step,
respectively, as textual comments for each definition (as done in the
spec document by now).

However, this should close my Action-687, Action-688, and Action-690 for
now.

best regards

Meiko

-- 
Dipl.-Inf. Meiko Jensen
Chair for Network and Data Security 
Horst Görtz Institute for IT-Security 
Ruhr University Bochum, Germany
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