Doesn’t distinguish PathExpr from PrimaryExpr

[simonjwright]

(quoting from XSLT Programmer’s Reference, Michael Kay, Wrox Press, 2000 page 387):

//section/para[1] returns all para elements that are the first para child of a section parent.
(//section/para)[1]returns the first element in the document that is a para child of a section parent.

XIA treats the first case as the second, and finds the second case syntactically incorrect.

[simonjwright]

I think the heart of the problem is that XIA’s grammar starts at Location_Path rather than at Expr: the specification says in the Introduction that

The primary syntactic construct in XPath is the expression. An expression matches the production Expr.

This may be a major change ...

[simonjwright]

I think the heart of the problem is that XIA’s grammar starts at Location_Path rather than at Expr: the specification says in the Introduction that

The primary syntactic construct in XPath is the expression. An expression matches the production Expr.

This may be a major change ...

Actually, to my huge surprise, I can simply change the %start LocationPath in the grammar to %start Expr! so the syntax problem is easily fixed. That leaves moving the point at which a Predicate is applied much earlier, to the result of applying the Step’s location path to the individual input context node rather than to the union of applying the location path to all the input context nodes.

The XPath 1.0 spec is so much shorter than the Ada LRM; but I suppose it shouldn’t be a surprise that there are deeply serious implications of apparently innocuous phrasings!

[simonjwright]

Fixed in release 1.3.0.