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Meaning of /descendant-or-self::node()

From: John Boyer <jboyer@PureEdge.com>
Date: Wed, 24 May 2000 15:55:10 -0700
To: "XML DSig" <w3c-ietf-xmldsig@w3.org>
Cc: <jjc@jclark.com>, <Steven_DeRose@Brown.edu>
I was just reading through the XPath spec for the umpteenth time when I
realized that although the node() function matches any time of node, it can
only match any type of node available on the given axis.  Furthermore, the
descendant and descendant-or-self axes of XPath exclude attribute and
namespace nodes (for some completely unfathomable reason).

Although the whole idea of having special axes for namespaces and attributes
is flawed and unnecessary (rather than simply leaving them as children of
the element and letting the fact that they have a *TYPE* of namespace or
attribute carry the information), we have to live with the recommendation.
Therefore, in places where I have in the past used the subexpression
"/descendant-or-self::node()" to mean ALL of the nodes in the parse tree
INCLUDING namespace and attribute nodes, it is necessary to substitute the
following subexpression: (//. | //@* | //namespace::*)

The union operator | combines the results of the three sets.  The first
subexpression (//.) is the abbreviated syntax for obtaining the root
document node and all of its descendants (which unfortunately includes only
elements, text nodes, processing instructions and comments).  The second
subexpression obtains all of the attributes in the entire parse tree, and
the third obtains all of the namespace nodes in the entire parse tree. The
union of the three sets contains all of the nodes in the parse tree.

Do you think there is any possibility that this might get fixed at some
point in the future?   It seems terribly tedious to have to go through such
hoops to simply say "give me a set containing all nodes in the whole parse
tree".  If not, I suppose we can be content that at least there is *some*
way to indicate what we want.

John Boyer
Software Development Manager
PureEdge Solutions Inc. (formerly UWI.Com)
Creating Binding E-Commerce
Received on Wednesday, 24 May 2000 18:55:23 UTC

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