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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XPath and XPattern (was Re: More on tamingSAX)
 Alan Gutierrez wrote: >* Jeff Rafter <lists@j...> [2004-12-27 14:40]: > > >>>> Say the test was /foo/bar/[baz2="test"]/baz1 >>>> >>>> <foo> >>>> <bar> >>>> <baz1/> >>>> <baz2>test</baz2> >>>> <baz3/> >>>> </bar> >>>> </foo> >>>> >>>> If your schema stated that the children were (baz1,baz2,baz3) >>>> wouldn't you have enough information to know to surrender when >>>> you reached baz3? >>>> >>>> > > > >>Unfortunately that solution doesn't win much against the DOM or other >>tree based models. >> >> > > It does if your predicate can fail early. > > > >>For example if your schema asserted (as you say) that the content >>model of bar be (baz1, baz2, baz3) and that baz2="test" always-- >>then you could "surrender" at the point of baz1 by starting with >>the assumption of validity. If the document turns out to not be >>valid you could raise some special error that says essentially-- >>hey we assumed this was valid and it isn't so we don't know if we >>reported the right thing or not. >> >> > > Or, to simply the implementation, a valid document could be a > requirement, which is what I was imagining. > > Ah. The pipelining approach. Perfectly sensible. Luckily most schema languages support validation via streaming API (Schematron is a bit of a problem, unless its query sublanguages are themselves restricted to our XPattern), so we don't run into the awkward problem that we have to tree up a document earlier in the pipeline for validation. But I'd say for a first pass at XPattern we leave out Schema aids and maybe they could be a subject of a later "level", as long as one could work in ecumenical schema language support. -- Uche Ogbuji Fourthought, Inc. http://uche.ogbuji.net http://4Suite.org http://fourthought.com Use CSS to display XML - http://www.ibm.com/developerworks/edu/x-dw-x-xmlcss-i.html Full XML Indexes with Gnosis - http://www.xml.com/pub/a/2004/12/08/py-xml.html Be humble, not imperial (in design) - http://www.adtmag.com/article.asp?id=10286 UBL 1.0 - http://www-106.ibm.com/developerworks/xml/library/x-think28.html Use Universal Feed Parser to tame RSS - http://www.ibm.com/developerworks/xml/library/x-tipufp.html Default and error handling in XSLT lookup tables - http://www.ibm.com/developerworks/xml/library/x-tiplook.html A survey of XML standards - http://www-106.ibm.com/developerworks/xml/library/x-stand4/ The State of Python-XML in 2004 - http://www.xml.com/pub/a/2004/10/13/py-xml.html 
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