W3C home > Mailing lists > Public > w3c-ietf-xmldsig@w3.org > January to March 2002

RE: XPath errors in specifications

From: John Boyer <JBoyer@PureEdge.com>
Date: Thu, 7 Mar 2002 09:51:52 -0800
Message-ID: <7874BFCCD289A645B5CE3935769F0B5232840F@tigger.PureEdge.com>
To: "TAMURA Kent" <kent@trl.ibm.co.jp>, <w3c-ietf-xmldsig@w3.org>


Hi Kent,

Perhaps you are using an implementation that is not functioning
properly.  Your general complaint is that the following is illegal:

'(' Expr ')' '[' PredicateExpr ']'

The parse sequence below illustrates the legality of this XPath
expression.  Note that the XPath language is rooted by BNF rule #14.
For each transformation, the notation -nn-> means that BNF rule nn was
used to get from the left hand side to the right hand side.

Expr 
-14-> OrExpr 
-21-> AndExpr 
-22-> EqualityExpr 
-23-> RelationalExpr 
-24-> AdditiveExpr 
-25-> MultiplicativeExpr 
-26-> UnaryExpr 
-27-> UnionExpr 
-18-> PathExpr 
-19-> FilterExpr 
-20-> FilterExpr Predicate 
-20-> PrimaryExpr Predicate 
-15-> '(' Expr ')' Predicate 
-08-> '(' Expr ')' '[' PredicateExpr ']'

From here it is easy to see that Expr can expand to //. | //@* |
//namespace::* and that PredicateExpr can expand to things like
not(self::comment()).

Regards,
John Boyer. Ph.D.
Senior Product Architect
PureEdge Solutions Inc.

-----Original Message-----
From: TAMURA Kent [mailto:kent@trl.ibm.co.jp]
Sent: Wednesday, March 06, 2002 8:18 PM
To: w3c-ietf-xmldsig@w3.org
Subject: XPath errors in specifications


The following XPath expressions are invalid according to XPath
1.0.  We can not add a predicate to '('...')'.

REC-xml-c14n-20010315:
2.1	(//. | //@* | //namespace::*)[not(self::comment())]
3.7	(//. | //@* | //namespace::*) 
[ 
   self::ietf:e1 or (parent::ietf:e1 and not(self::text() or self::e2)) 
   or 
   count(id("E3")|ancestor-or-self::node()) =
count(ancestor-or-self::node()) 
] 

CR-xml-exc-c14n-20020212:
2.1	(//. | //@* | //namespace::*)[ancestor-or-self::n1:elem1]
2.2	(//. | //@* | //namespace::*)[ancestor-or-self::n1:elem2]


In general,
	(//. | //@* | //namespace::*)[expr]
must be
	(//.[expr] | //@*[expr] | //namespace::*[expr])

-- 
TAMURA Kent @ Tokyo Research Laboratory, IBM
Received on Thursday, 7 March 2002 12:52:25 GMT

This archive was generated by hypermail 2.2.0 + w3c-0.29 : Thursday, 13 January 2005 12:10:14 GMT