Add support for ABAP CDS

[FreHu]

Already tried in #4592, but the repo had issues with the license and build. Submitting again with a new repo (and color). The grammar is exactly the same, but the repo does not contain the incompatibly licensed snippets.

As previously discussed, I'm only including one of the extensions for popularity reasons. Hopefully this will improve in the future.

Description

Hi! This PR adds support for the ABAP CDS language, which is used for defining what is basically database views on steroids. It goes hand in hand with the ABAP language, which is already recognized.

The language is not widely used outside of the SAP ecosystem, but even the public github contains a number of repositories now. Many more can be found on github enterprise servers.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3Aasddls+define+view
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      https://github.com/hardyp/AbapToTheFuture03/tree/master/src/zmonsters_p02_transactional/zmonsters_c07_database
    • Sample license(s): MIT
  • I have included a syntax highlighting grammar: here
  • I have updated the heuristics to distinguish my language from others using the same extension.
    • I believe asddls is a rare enough extension to prevent any conflicts.

Notes

• To simplify legal matters, I would like to note that though I am a SAP employee, I am making this request as my own person in my spare time and not on behalf of SAP.

[pchaigno]

I've downloaded the 804 files associated to this extension using Harvester and found 104 repositories by 51 users. This is clearly low given our requirements. The extension is also unlikely to conflict with another one. I'll leave the final decision to @lildude.

The pull request looks good to me otherwise.

[lildude]

I've downloaded the 804 files associated to this extension using Harvester and found 104 repositories by 51 users. This is clearly low given our requirements.

Yeah, unfortunately still too low. Popularity for inclusion is based on GitHub.com stats as that's the only thing we can measure. It's probably best to add this to #4219 and monitor the growth.

[FreHu]

Alright I guess. I'll try to motivate people to host more of their code on github, but unfortunately, most devs within my reach simply can't make their code public.

This is purely philosophical rambling from my side as I'm aware you currently don't have a better metric to judge popularity by, but:

I'm taking the "build it and they'll come" approach, but in this case, they need to come before I can build it, which is a bit of a conundrum. SAP is used by major companies which can be very resistant to change and have yet to adopt proper versioning and open source practices, but somehow expect perfect tooling to be available before they move a finger. As github is almost the de facto standard place for sharing code, lack of support there can thwart adoption of the language (and the practices).

Anyway, I'm sure this will resolve itself over time, I'd just like to make that time shorter.

[dellagustin]

Please keep in mind the github enterprise use case.
ABAP code is not often made open source, but I bet there are a number of companies already hosting their ABAP code on their enterprise instances.

@FreHu , I can also see people using the extensions .cds (80 code results) and hdbcds (727 code results), does it make sense to extend your PR to also cover these two extensions?

[FreHu]

No, because .cds and .hdbcds are a different language - CAP CDS. This request adds ABAP CDS.

Why we name languages so similarly we can't tell them apart is beyond me.

Also the usage has to be per extension, not in total.

[pchaigno]

Closing in favor of #4219. We'll monitor the popularity of the extension there.

[lildude]

Good news, popularity of the .asddls extension is now sufficient for inclusion so I'm re-opening this PR.