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> as everything is a node, one can match a node like this :
> node()
I assume we're talking about XPath path expressions here, not XSLT match
patterns: so it might be better to use the verb "select" rather than
"match".
Yes, node() is short for child::node(), it selects any node on the child
axis.
> which works well in the axis that are walking through the tree
> what about other axis ?
> @node()
> namespace::node()
> which would give the same as (respectively) :
> @*
> namespace::*
Correct.
> and above all what about :
> @comment()
> @text()
> @p-i(target)
> namespace::comment()
> namespace::text()
> namespace::p-i(target)
> which are all empty if they are legal
>
> but are they legal ?
Yes, they are legal in XPath 1.0. They all select an empty set of nodes. In
XPath 2.0, with static typing, they have a static type of empty-sequence(),
which is a type error that can be reported at compile time if the processor
chooses to do static type checking.
>
> here are the last ones :
> /@*
> /namespace::*
>
Again these are legal, and select nothing. The same applies to, for example,
@*/@*
>
>
> Will you be hurted if someone (like me) was writting
> something like this :
> $foo/@bar/@oof
>
If your data conforms to the XPath data model, then this will select
nothing. If you want to design a language similar to XPath that works on a
different data model, for example one in which attributes can have
attributes, then you are free to do so (but please don't call it XPath).
Michael Kay
http://www.saxonica.com/
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