Better ToggleComments support for Comment and Doc

[huacnlee]

Check for existing issues

• Completed

Describe the feature

We have line_comments in language config.toml.

For example the Rust:

name = "Rust"
grammar = "rust"
path_suffixes = ["rs"]
line_comments = ["// ", "/// ", "//! "]
autoclose_before = ";:.,=}])>"
brackets = [
    { start = "{", end = "}", close = true, newline = true },
    { start = "[", end = "]", close = true, newline = true },
    { start = "(", end = ")", close = true, newline = true },
    { start = "<", end = ">", close = false, newline = true, not_in = ["string", "comment"] },
    { start = "\"", end = "\"", close = true, newline = false, not_in = ["string"] },
    { start = "/*", end = " */", close = true, newline = false, not_in = ["string", "comment"] },
]
collapsed_placeholder = " /* ... */ "

But by my test, the Toggle Comments command just work for the first item in line_comments.

If applicable, add mockups / screenshots to help present your vision of the feature

As shown in the screen recording, if ToggleComments can correctly handle Rust's /// and //!, it will be more convenient for us to write documents.

For example, many times we need to write a large section of Rust code example. So we many write the code first, and then add /// prefix to them. If the ToggleComments can handle that, we can just select the all new addition code and run ToggleComments to add the prefix.

[osiewicz]

Yeah, back in #6713 we've ommited Toggle comments support and additional entries in line_comments array are there mostly for comment continuations. I'll tackle Toggle comments support though.

[osiewicz]

Oh, now I get why we didn't add support for Toggle Comments there; how do you decide which comment flavour to add? Like:

For example, many times we need to write a large section of Rust code example. So we many write the code first, and then add /// prefix to them. If the ToggleComments can handle that, we can just select the all new addition code and run ToggleComments to add the prefix.

How would you decide that we should insert /// as a comment prefix and not // or //!?

[huacnlee]

What if we check what type of prefix is the nearest Comment before or after the current line. Then use the same prefix with matching one of the line_comments?

I am not sure if this can be done.

Even that, with the Uncomment case, we can that to remove the right prefix by matching the line_comments.