Issue 26: Added detection of bracket and pipe blocks.

[andycraig]

Closes #26

If no editor text is selected, r.runSelection will check around the line on which the cursor lies and send to the R console the chunk of code necessary to make a complete code line (by matching brackets and following pipes and other operators).

Some examples of code chunks it will send to the console:

1. Multi-lined bracketed expressions:

a = list(x = 1,
         y = 2,
         z = 3)

a[1
    ]

2. Lines joined by pipes and other operators:

library(magrittr) # For %>%
library(ggplot2)

1 + 1 %>%
    print()

ggplot(aes(speed, dist), data = cars) +
    geom_point()

3. Combinations thereof:

library(magrittr) # For %>%

list(x = 1,
        y = 2,
        z = 3) %>%
    print()

If the algorithm encounters unmatched brackets, it just sends the current line.

Behaviour differs from that of RStudio in some cases. Roughly, vscode-R will send the smallest valid block of code, whereas RStudio sends the largest () or [] expression within the smallest {}. Here is an example:

(                     # 1. RStudio and vscode-R send lines 1-9
    {                 # 2. RStudio and vscode-R send lines 2-8
        (             # 3. RStudio and vscode-R send lines 3-7
            (         # 4. RStudio sends lines 3-7; vscode-R sends lines 4-6 
                1     # 5. RStudio sends lines 3-7; vscode-R sends line 5
            )         # 6. RStudio sends lines 3-7; vscode-R sends lines 4-6
        )             # 7. RStudio and vscode-R send lines 3-7
    }                 # 8. RStudio sends lines 1-9; vscode-R sends lines 2-8
)                     # 9. RStudio and vscode-R send lines 1-9

The algorithm would ideally ignore brackets in strings, but I haven't implemented that feature. If it proves to be a problem in practice then it could be dealt with in a separate issue/PR.

[Ikuyadeu]

@andycraig , Thank you awesome Pull Request!
I think this change can be merged.
@Ladvien , how do you think this?

[Ladvien]

@Ikuyadeu, it looks great! Much better than what I had. Sadly, I’ve not had a chance to run it. But if it works, I say merge it.

Thanks @andycraig

[Ikuyadeu]

@Ladvien Thank you for your review!
I'll merge and check this tonight.
And, if it does not have some problems, publish as the new version!

[Ikuyadeu]

@andycraig OK, now little fixed for maintainability, and published as the v0.6.1!
Thank you for your good fix!

[andycraig]

@Ikuyadeu Thank you for your readability/maintainability fixes, I like them and I learnt a couple of things from them.

@Ikuyadeu @Ladvien Thank you both very much! I love this extension and I'm happy to be able to make a contribution.