add go to definition

[andycraig]

Closes #34

This PR adds Go to Definition functionality.

@Tutuchan added the infrastructure and code to go to definitions of functions in packages; I added code to go to definitions in local files.

The following rules are used:

1. Go to definition on a function with a pkg:: qualifier will look for that function first in package pkg and then in local files;
2. Go to definition on a function without a pkg:: qualifier will look for that function first in local files and then in loaded packages.

Note that the language server only becomes aware of functions in local files as those files are registered via didOpen etc. A future feature that registers, e.g., all files in the current project would make Go to Definition more useful.

@Tutuchan I have rebased your commits and my commit onto master.

Running the unit tests using devtools::test() requires that the package already be installed (not just with devtools::load_all()). Otherwise, the unit tests hang. This seems to be the case with master too, though.

[minkir014]

Do you know why the last commit failed????

[minkir014]

And does these packages go to definitions for all packages that are installed??? I mean if I have code like that library(shiny) and I put the mouse over shiny and clicked go to definition. Would it go to definition for that??????

[andycraig]

Hi @minkir014, the checks failed for two reasons:

1. The documentation didn't quite meet CRAN requirements, and
2. Some unit tests were failing because the language server takes a bit longer to run in Travis CI and I had it requesting data before the data was ready.

Happily, both those issues seem to be resolved now.

For packages, there isn't really a 'definition' to go to. So in the library(shiny) example it wouldn't do anything. But, if you clicked on runExample in shiny::runExample it would go to the definition for runExample.

[Tutuchan]

@andycraig this is great work, thank you.

A future feature that registers, e.g., all files in the current project would make Go to Definition more useful.

Yes, this would be great!

Running the unit tests using devtools::test() requires that the package already be installed (not just with devtools::load_all()). Otherwise, the unit tests hang. This seems to be the case with master too, though.

Yes, I don't know why it behaves that way but I noticed the same behavior.

[randy3k]

@andycraig excellent work. I will take a look as soon as possible. @Tutuchan feels free too give any comments.

[minkir014]

Note that the language server only becomes aware of functions in local files as those files are registered via didOpen etc. A future feature that registers, e.g., all files in the current project would make Go to Definition more useful.

Do you mean that go to definition won't work until the files are opened for local purpose???

[andycraig]

@randy3k @Tutuchan Thanks both! @Tutuchan Your code was very clear and easy to continue on with :)

[andycraig]

@minkir014 For functions in local files (not packages), that’s correct. This is the same for other features like Code Completion and Hover.

[kforner]

Yes, I don't know why it behaves that way but I noticed the same behavior.

It happened to me. I think this is because the R process run by https://github.com/REditorSupport/languageserver/blob/master/R/languageclient.R#L18 does not find the package, since it is not installed. But there is not any error check at this point.
I propose to add a sleep, then a check that the process is still alive, otherwise raise an execption with the error stream content.
In the my docker pull request, I work-around it by first installing the package.

[andycraig]

Hi @kforner, thanks for looking at this. I created a separate issue for it (#39).

[randy3k]

I don’t think I will have time review it in details in the near future. After a quick skim, I guess we could merge it first and evaluate.

[andycraig]

@randy3k Sounds good. If you have comments in the future, let me know and I'll be happy to make fixes etc. as required 👍