On Nov 17, 2009, at 1:27 PM, Thomas Mortagne wrote:
> Hi,
>
> Among other things the goal is to be able to directly do
>
> parser -> renderer
>
> instead of
>
> parser -> XDOM -> renderer
>
> Thing is all our parsers (including Doxia and WikiModel parsers) are
> streaming based. So For example we generate a XDOM from events in
> theses so instead of converting WikiModel events and generate XDOM all
> in once we would convert WikiModel events to XWiki events (i.e.
> org.xwiki.rendering.listener.Listener) and generate the XDOM from
> XWiki events.
>
> Here are some use cases for this new feature:
> * xml parser read events and need to generate a XDOM from them so
> it would be nicer to have a common XDOMGeneratorListener to generate
> XDOM from Listener instead of having one in xml parser another in
> WikiModel, Doxia...
> * when we convert from one syntax to another we don't execute
> transformations so it would be better to have streaming conversion
> support for this
> * when we save XHTML content coming form WYSIWYG we don't execute
> any macro so it would be better to use streaming parser here too
> * some rendering tests are executed without transformations, could
> be better to execute them in pure streaming
> * streaming renders are not really usable without streaming
> parsers, parser->render is way more common use case than someone
> calling renderer events by hand
> * could be useful in wiki importers too where we don't execute
> macros
> * It's generally more consistent anyway to have streaming parser
> since we have streaming renderer
All these use cases are valid. I just wanted to mention that even
though they're real they won't help us since we're using non-streaming
parsers to view page content so even if we can import/save/etc using a
streaming parser, we'll still need to be able to have it all in memory
for viewing the page. In term of performance at execution time I doubt
it's going to make any change (for ex when saving from the wysiwyg).
Thus for now I don't see a real use case for us inside XWiki. I can
see some use cases when the rendering module is used outside of XWiki
(provided there's no need for macros).
All that said, I agree it's good to have it.
> Like for renderers I propose to have two different parsers components
> interfaces for the block parser and the stream parser.
>
> Basically all this means introducing:
>
> public interface StreamParser
> {
> /**
> * @return the wiki syntax the parser is implementing
> */
> Syntax getSyntax();
>
> /**
> * @param source the content to parse
> * @param listener receive event for each element
> * @throws ParseException if the source cannot be read or an
> unexpected error happens during the parsing. Parsers
> * should be written to not generate any error as much
> as possible.
> */
> void parse(Reader source, Listener listener) throws ParseException;
> }
>
> (and internally refactor most of the parsers to use a common Listener
> events based XDOMGeneratorListener).
>
> Here is my +1
+1
Thanks
-Vincent
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