Hi Sivan, On 12/11/11 10:39 AM, "ext Sivan Greenberg" <si...@omniqueue.com> wrote:
>Hi Lars! > >On Sat, Dec 10, 2011 at 11:32 PM, <lars.kn...@nokia.com> wrote: >> there were quite a few discussions and requests over the last months to >> add Json support as part of QtCore, and maybe integrating one of the >> existing parsers. > >There were also discussions and even a couple of bug report about >adding "native" (a'la making Json first class citizen) support to QML >as well (I guess this means adding it to the QDeclerativeContext >engine?) , in favor of having one implementation that'd be standard >and fast - https://bugreports.qt.nokia.com/browse/QTBUG-12117 . That might make sense, but would need some further discussion on how to best do it. I have some ideas, but need to validate this with the QML and V8 experts :) > >> >> I was however never really happy with them. Mainly because they all >>parse >> into a QVariant(Map), and don't offer any real API to create and modify >> Json. In addition, I believed that it was possible to create a faster >> parser, and wanted to have a binary representation for the parsed Json. >> >I wonder if the QML implementation in the bug report would suffer from >the same (or perhaps worse?) performance issues? If it uses qjson behind the scenes it'll be a lot slower than it has to be (see my post a few minutes ago). > >> So I sat down over the last weeks and implemented hacked on something on >> my own. You can see the current state in our first playground project >>that >> Sergio created for me yesterday. You can clone it from >> >>ssh://usern...@codereview.qt-project.org:29418/playground/qtbinaryjson.gi >>t >> > >So, could be bind this to have an QML "native" JSON implementation and >handling? Perhaps also to tie it in to have a JsonModel just as the >XmlListModel uses XML? It's possible. The main question will be how to inject it into QML without converting the data. > >> Things look rather promising, and I consider the code to be mostly >>feature >> complete. There's work to be done on the API, and documentation is still >> completely missing, but most of the other pieces are there. >> >/me keen to find a spare weekend to check this out. > >> What I have right now: >> >> * A binary representation of Json, that can be simply mmap'ed from a >>file, >> or copied around. This gives us an extremely cheap way to load and save >> Json objects in binary form. > >Would this enable us to store complete binary chunks (files, network >dumps etc..) as BSON allows? I have some use cases for this if this is >possible. You can simply dump the whole Json object to a file and reread it from there at basically zero cost. > >> >> The binary representation is optimized for fast reading. The binary >>format >> is relatively compact and stores the whole object in one blob. > >Is this a standard binary format of JSON, or something of your own devise? It's something I wrote. I wanted it to be something that you can simply mmap from a file and use without ever having to parse anything to make saving and restoring of json objects as cheap as possible. The problem with bson is that it's a streaming format that still requires parsing and as such was unsuitable for some of the use cases I have. > >> There's a bit of work still required to finish it, but I would like to >> start the discussion about including it into QtCore anyways. I'd also be >> happy about any feedback. > >Many thanks for this! You're welcome :) Cheers, Lars _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
