- From: Kay, Michael <Michael.Kay@softwareag.com>
- Date: Mon, 2 Sep 2002 13:58:09 +0200
- To: "Ed.Willink" <Ed.Willink@uk.thalesgroup.com>, "'public-qt-comments@w3.org'" <public-qt-comments@w3.org>
> The Aug 16 Xpath 2.0 WD is much improved on the 30-Apr WD. > > There are however problems. > > instance of attribute > --------------------- > > A problem arises when an instnace of is followed by any of > > the or/and/for/quantified/if precedence operators > > since there is then an ambiguity between > > {... instance of attribute operator} ... > > and > > {... instance of attribute} operator ... > > Perhaps some <> annotations should specify a resolution for > the above, presumably as the normal left maximisation, since > parentheses can be used to force termination between > attribute and operator. > > However the ambiguity is unplesasant, and could be better > resolved with parentheses in the grammar: instance of (SequenceType). I'm personally inclined to agree with you. The ambiguity can be resolved by some kind of backtracking, but it's not nice. I think a number of people are uneasy about various aspects of the SequenceType production, and this is something we need to take another look at. > > AtomicType > ---------- > > The grammar for ItemType is trivially impossible since > AtomicType is a QName and so covers node and comment etc > which are distinct ItemType's. > I guess we're assuming some kind of "first match" resolution here. We need to be more explicit about the assumptions. > > Lexical states > -------------- > I'll leave these comments to be addressed by people who understand the parsing technology better than I do. Michael Kay Software AG
Received on Monday, 2 September 2002 07:58:25 UTC