[feature] Allow automatically selecting FixIt action by pattern

[filipelbc]

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Why this change is necessary and useful

Currently, it is difficult to automate application of some fixits, because it requires manual input to select a fixit.

For instance, suppose I want to frequently "organize imports" or "replace var by the type name" (in Java). I know the action is available, but I still need to wait for the list to show up and then select the option...

This PR adds support for selecting a FixIt based on a regex pattern provided when running the command:

:YcmCompleter FixIt <some-pattern>

Eg:

:YcmCompleter FixIt Change\ type

If this change makes sense, let me know, and I can try to also update the docs for it.

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This change is 

[puremourning]

Hmm
Thanks

I feel like this is better implemented in the server than the client. Ie the second argument to fix it can be used to filter the results server side.

I’m also unsure if regex is ideal. Any reason not to use an exact match?

Reviewable status: 0 of 2 LGTMs obtained

[codecov]

Codecov Report

Merging #4083 (4da74f4) into master (2d1de48) will increase coverage by 0.02%.
The diff coverage is 100.00%.

Additional details and impacted files

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##           master    #4083      +/-   ##
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+ Coverage   86.46%   86.49%   +0.02%     
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  Files          33       33              
  Lines        4337     4346       +9     
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+ Hits         3750     3759       +9     
  Misses        587      587              

[filipelbc]

@puremourning

I feel like this is better implemented in the server than the client. Ie the second argument to fix it can be used to filter the results server side.

Makes sense. I could try submitting a patch on the server side if you would give me some pointers as where the changes would need to be.

I’m also unsure if regex is ideal. Any reason not to use an exact match?

Matching exactly "the entire" text is not feasible because it varies. For instance, if I want to replace var by the specific type, I'd need to know the type ahead of time (for the match) and then there would be no point in running the command in the first place.

Matching exactly "a part of" the text would work as far as my current use-case goes, which is quite limited. Using a regex makes it more flexible, but I can't say for sure it is "necessary".

Also, I don't know if there are other fields besides text that might be better suited for the matching.

[puremourning]

if you would give me some pointers as where the changes would need to be.

we'd probably do this in ycmd/completers/language_server/language_server_completer.py in GetCodeActions. The arguments to the command are passed in the request_data object.