Provide completion for session symbols

[renkun-ken]

What problem did you solve?

Closes #164
Closes #170

This PR provides

• Completion of session symbols, showing symbol str in documentation. The latest languageserver already supports workspace completion (global variables in code), scope completion (local variables in scope). This PR adds session completion as a new kind of completion.
• Completion of elements in list-like objects (list, environment, S4 objects). As for R6 object, they are basically environments so that they are covered too.
• Completion of symbols in brackets [], mainly for subsetting and extracting using "col", or accessing elements with dynamic scoping in brackets (usage of data.table).

(If you have)Screenshot

Session symbol completion

Completion for elements in list-like objects

Completion for brackets

Quoted symbol:

Element completion for dynamic scoping in data.table:

[hongyuanjia]

Comments below were original posted in REditorSupport/languageserver#75. @renkun-ken requested to also post them here which are more relavent to this PR.

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Neither current vscode-R release and @renkun-ken's cutting-edge version can do the completion for my use case.

Here is a reproducible example.

library(eplusr)
path_idf <- system.file("extdata/1ZoneUncontrolled.idf", package = "eplusr")
idf <- read_idf(path_idf, use_idd("auto"))
#> IDD v8.8.0 has not been parsed before.
#> Try to locate `Energy+.idd` in EnergyPlus v8.8.0 installation folder 'C:/EnergyPlusV8-8-0'.
#> IDD file found: 'C:\EnergyPlusV8-8-0\Energy+.idd'.
#> Start parsing...
#> Parsing completed.

class(idf)
#> [1] "Idf" "R6" 

names(idf)
#>  [1] ".__enclos_env__"     "clone"               "print"              
#>  [4] "run"                 "save"                "is_unsaved"         
#>  [7] "to_table"            "string"              "to_string"          
#> [10] "is_valid"            "validate"            "replace_value"      
#> [13] "search_value"        "del_object"          "ins_object"         
#> [16] "set_object"          "add_object"          "dup_object"         
#> [19] "paste"               "update"              "load"               
#> [22] "insert"              "rename"              "del"                
#> [25] "set"                 "add"                 "dup"                
#> [28] "search_object"       "object_in_class"     "objects_in_relation"
#> [31] "object_relation"     "objects_in_group"    "objects_in_class"   
#> [34] "objects"             "object_unique"       "object"             
#> [37] "object_num"          "is_valid_name"       "is_valid_id"        
#> [40] "object_name"         "object_id"           "definition"         
#> [43] "is_valid_class"      "is_valid_group"      "class_name"         
#> [46] "group_name"          "path"                "version"            
#> [49] "initialize"

^{Created on 2020-01-01 by the reprex package (v0.3.0)}

In vscode, when I type idf$, nothing from the names pops up.

Please note that idf object contains active bindings. Not sure if this may influence the auto-completion.

[renkun-ken]

Would you mind check is.list(idf) and is.environment(idf) and take a look at ${workspaceFolder}/.vscode/vscode-R/{pid}/globalenv.json and can you see idf has these names in this file?

I tried with environemnts with active bindings but everything looks normal here.

[hongyuanjia]

It's embarrassing but I noticed that I did not attach the R session. Because R session created from vscode did not respect my .Rprofile under ~/Documents (Windows default). After I attach the session (by manually run the command in vscode-R README), I can confirm the auto-completion works as expected.

Sorry for the bother.

[hongyuanjia]

@renkun-ken I can confirm that is.list(idf) returns FALSE and is.environment(idf) returns TRUE. And below is the contents of file globalenv.json which indeed contains all the names of idf object.

{"path_idf":{"class":["character"],"type":"character","length":1,"str":"chr \"C:/Users/hongy/R/eplusr/extdata/1ZoneUncontrolled.idf\""},"idf":{"class":["Idf","R6"],"type":"environment","length":49,"str":"-- EnergPlus Input Data File ---------------------------------------------------","names":[".__enclos_env__","clone","print","run","save","is_unsaved","to_table","string","to_string","is_valid","validate","replace_value","search_value","del_object","ins_object","set_object","add_object","dup_object","paste","update","load","insert","rename","del","set","add","dup","search_object","object_in_class","objects_in_relation","object_relation","objects_in_group","objects_in_class","objects","object_unique","object","object_num","is_valid_name","is_valid_id","object_name","object_id","definition","is_valid_class","is_valid_group","class_name","group_name","path","version","initialize"]}}

Thanks for your great work!

Wish this feature can be implemented into the language server, because I mainly use Vim with the language server for my R work. Anyway, thanks to you and other contributors, vscode-R indeed becomes a rich-featured R IDE now.

[renkun-ken]

@hongyuanjia, Thanks for your testing. As we discussed at REditorSupport/languageserver#75, languageserver is designed to only perform static analysis, i.e., no active R session is assumed. Session-related features are editor-specific at the moment. Maintainers of R support in other editors could implement such features using similar methods (we use a file-based method in vscode) or come up with better methods, or similar with RStudio methods (socket-based method), but anyway it is editor-specific.

[renkun-ken]

@Ikuyadeu @andycraig This PR is a LGTM. Please take a look.

[andycraig]

This looks amazing and I will try to review it this weekend.

[andycraig]

I have tested this on Windows and all the features work. I haven't reviewed the code carefully but I think it is fine to merge. It is a great addition!