RDFa support

[nvdk]

Thanks for building this library! Would you be interested in adding RDFa support to rio and what's the best way we can help out with that?

[Tpt]

Hi! Thank you so much! I would love to get RDFa support. A streaming parser would be amazing but a DOM-based approach is imho fine too if you prefer.

On where to implement it, I am not sure. I am currently in the process of merging the Rio libraries into the main oxigraph/oxigraph repository in order to reuse all Oxigraph tooling (the oxrdf library instead of rio_api::model, way better test suites support...). I just finished a rewrite of the Turtle parser with that should allow async I/O support and I still need to port the RDF/XML parser.

If you want to do the implementation work yourself, I can write a draft MR to Oxigraph that setups a crate for RDFa parsing with interface stubs and does the needed piping to run the RDFa testsuite and then you can do the actual implementation work. But if you prefer, feel free to start working in your own repository and we can the work to upstream it.

On which XML/HTML parser to use, I am not sure. The RDF/XML parser uses quick-xml but it does not support HTML. A possible library for that is html5ever but it's sad to have to manage two different parsers with very different APIs.

[nbittich]

Although at a very early stage, I've built a poc for an rdfa processor (https://github.com/nbittich/graph-rdfa-processor).
Can be tested here (wasm build): https://nbittich.github.io/graph-rdfa-processor/

It uses Scraper, I've mainly targeted html 5 so it might not work well in other format.

If I can help, please let me know.

[Tpt]

@nbittich Sorry for the slow answer. Thank you! It's amazing! Your parser has quite a lot of dependencies so I am not sure to make Oxigraph depend on it by default but I have added a link to it to Oxigraph documentation: oxigraph/oxigraph#763