SoC Update: Week 10: GXml

[Richard Schwarting <aquarichy gmail com>]

Hello list!  Thank you to those who read these e-mails.  I hope they are of some interest!

This past week has been spent doing

• Desktop Summit preparations!  This actually consumed most of my Friday, even, and while it's not strictly part of GSoC, I am hoping attending the Desktop Summit will benefit GXml. :)
• Polishing code, including the Document class and DocumentFragment.  DocumentFragment through libxml2 didn't behave exactly as I had hoped, so I had to add more local logic in GXml.  I've tried to keep the amount of local logic to a minimum, but that has sometimes involved rewriting chunks of code or redesigning a few things, which can take more time than just writing the DOM Level 1Core's functionality myself.
• NodeList support.  NodeList is iterable and supports methods from GLib.List, but does not subclass GLib.List, since depending on the usage, it is sometimes backed by libxml2's nodes' linked list.  One of my favourite features that I worked on this past week which took a little bit of planning and prototyping was having a live NodeList for get_elements_by_tag_name ().  By "live", we mean that if you obtain a NodeList of descendant elements from element A with tag name B, if you later add a new descendant to A with the tag name B, it should be present in the earlier-obtained NodeList.  This now involves each element maintaining a list of such NodeLists that have been requested at that element, and addition and removal of nodes to an element now notify its ancestors which check whether they're watching a NodeList for the new/old element's tag name.  If so, they update the NodeList.  Despite being happy to have implemented it, as its an API I used in other DOM implementations, I'm considering disabling this functionality by default, because I can imagine it being expensive when you're not actually using get_elements_by_tag_name () but have many insertions or deletions to do via the DOM, and letting users enable it at the Document level.  Or enabled by default with an option to disable.  We'll see.
• Namespace support investigation.  Support for namespaces exists in DOM Level 2 Core, but I believe it would require too much work beyond the scope of this GSoC right now to implement all the namespace-related changes from DOM Level 2 Core.  I looked at libgdata to try to understand just where and for what it required namespace support, so perhaps I can implement a subset now at the Document level, and worry about it at the Element and Attr level later.  That's going to be a focus of this week, as well as polishing the libgdata patch so I can give it to Philip Withnall for comments.

I'll be making my way from Guelph, Ontario to Berlin, Germany over part 
of  Wednesday and Thursday this week, so my next update might be longer 
or shorter depending on how well I can work on planes and trains!

Cheerio!
   Richard Schwarting