- From: Philippe Michiels <philippe.michiels@ua.ac.be>
- Date: Tue, 15 Jul 2003 16:36:13 +0200
- To: www-ql@w3.org
- Cc: jan.hidders@ua.ac.be
Hi,
There seems to be some curiosity in the normalization of the double slash
operator in XPath expressions (XQuery 1.0 and XPath 2.0 formal semantics
draft), which is normalized as follows:
["//" RelativePathExpr]Expr ==
[fn:root( self::node() ) "/" descendant-or-self::node() "/"
RelativePathExpr]Expr
Without any predicates, these expressions, indeed return the expected result.
However, when an index is applied after the // operator, for instance:
//a[2],
a problem arises. Now, this path expression is (in a first step) normalized
into
/descendant-or-self::node()/child::a[2]
(selects all second a-children of the descendant nodes),
which is something totally different than
/descendant::a[2]
(selects the second a-descendant)
which is the behavior I would expect. Off course, someone who knows the
normalization rules understands why the two expressions yield different
results, but is this really what the designers of XPath had in mind?
-- Philippe
-----------------------------------------
Philippe Michiels
ADReM Research Group -- dept. WisInf
Universiteit Antwerpen
Middelheimlaan 1
2020 Antwerpen
tel: 32 (3) 218 0880
http://win-www.ruca.ua.ac.be/u/michiels
-----------------------------------------
Received on Tuesday, 15 July 2003 10:37:42 UTC