Today I checked in my first XQuery parser stuff, with some hack on System.Xml.Query.XQueryCommand (in System.Data.SqlXml.dll). DISCLAIMER: It won't do anything other than parse ;-) I tried all the query examples contained in XQuery Use Cases, though it is still incomplete. Besides "fn:empty" function call, only 3 examples fail (The reason why fn:empty fails is like what this message appeals - empty() and empty(item) are still? ambiguous to my parser). I put those extracted examples here.
The next stage is to design static context model from current abstract syntax tree. And it will be concurrently done with kinda XPathItemIterator design. Other new XML 2.0 API might be implemented when I want to run away from XQuery I want to use them in XQuery implementation and/or I want to fill missing bits, as I have done in this month.
BTW, recently W3C published the updated working draft of XML Schema component designator. If you know XQuery, you will notice that the spec targets exactly as the same one as the terminal named SchemaContextLoc in XQuery 1.0. To me, it looks like the near future version of XQuery 1.x will replace that SchemaContextLoc part and XQuery 1.0 might soon get obsolete like http://www.w3.org/TR/WD-xsl in a few years (unless that Component Designator spec gets discarded).
Of course, that does not mean "it is no worth learning XQuery after publication of 1.0 spec". XQuery might be one of the most useful XML processing language. It just means that "some" schema-related part of XQuery would become obsolete. It is also true to XPath 2.0 and thus XSLT 2.0.
One possibility is that the component designator spec work soon gets W3C recommendation status, and XQuery 1.0 uses that spec. That would be nice, but early implementation of XQuery will be still unstable then.
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