Hi Hans-Juergen,
Am 23.11.2012 06:59, schrieb Hans-Juergen Rennau:
are there already any plans for implementing the XQuery 3.0 feature "window clause in FLWOR expressions"?
I actually implemented them (and the other missing features of General FLWOR Expressions) in the `stack-frames` branch [1] some time ago, but the code unfortunately bit-rotted quite a bit while I wrote my bachelor thesis. I'm currently in the process of integrating the changes back into `master` [2].
It seems to me so interesting as it allows the creation and evaluation of "self describing item streams", that is, streams of XDM items with interspersed control items which define and annotate sub units (windows) of the stream total, thus effectively translate the stream of items into a stream of larger units, in analogy to XML tags which translate a stream of characters into a stream of information items...
Yes, they are quite powerful and I regularly miss them when writing XQuery. If you want to play around with them, you can download an older snapshot of the `stack-frames` branch from my Dropbox [3]. Just keep in mind that it's still based on BaseX 7.2.1 and probably not quite bug-free yet.
Hope that helps, Leo
[1] https://github.com/BaseXdb/basex/tree/stack-frames [2] https://github.com/BaseXdb/basex/issues/572 [3] https://dl.dropbox.com/u/22915638/basex-7.2.1-stack-frames.jar