Add support for R packages (CRAN)

[stefanbuck]

In OctoLinker/OctoLinker#1037 @edavidaja offered help to get OctoLinker work with R.

R packages are hosted by Comprehensive R Archive Network (CRAN). A web version of each package manifest is available at the link: https://cran.r-project.org/package={package} (e.g. https://cran.r-project.org/package=flextable)

Packages with web pages list them in the URL field of the DESCRIPTION file; however, not all packages have a webpage. There is a GitHub Mirror of CRAN packages at https://github.com/cran, which has the source code, including the manifest, for any package on CRAN.

First we need to figure out wether or not CRAN has an endpoint that returns a JSON document so we can leverage our universal config which makes adding new registry support super easy.

So, does CRAN have such an endpoint @edavidaja ?

[edavidaja]

Nope, CRAN does not return a JSON response, just raw HTML.

[stefanbuck]

https://www.r-pkg.org is using CouchDB and I wonder if this is a service we can / should rely on.

[edavidaja]

That would work: the GitHub cran mirror I mentioned before is generated by the same source, and the maintainers are well known r community members.

[stefanbuck]

Ahh I see, that should simplify things a lot. I'm on my phone right now so hard to do proper research on this, but looks like URLs set in the URL field are separated by comma https://crandb.r-pkg.org/usethis. The current implementation does not support such a custom format.

I think it makes sense to split the work between you and me. I can look into the API side of things later this week. Once I'm back home tonight, I'll point you to the steps required to make the browser extension side happen.