Add spread to syntax highlighting

[texastoland]

Fixes #173.

Generated tokens for:

def cmd [--flag (-f) ...rest] {
  [ ...$rest ]
  { ...$rest }
  all --flag -f ...$rest
}
cmd --flag -f ...$rest
^cmd --flag -f ...$rest

• def cmd [
  • ...
    1. keyword.control.nushell
    2. meta.function.parameters.nushell
    3. source.nushell
  • rest
    1. variable.parameter.nushell
    2. meta.function.parameters.nushell
    3. source.nushell
• ] {
  • [
    • ...
      1. keyword.control.nushell
      2. meta.table.nushell
      3. meta.function.body.nushell
      4. source.nushell
    • $rest
      1. variable.other.nushell
      2. meta.table.nushell
      3. meta.function.body.nushell
      4. source.nushell
  • ]
  • {
    • ...
      1. keyword.control.nushell
      2. meta.expression.braced.nushell
      3. meta.function.body.nushell
      4. source.nushell
    • $rest
      1. variable.other.nushell
      2. meta.expression.braced.nushell
      3. meta.function.body.nushell
      4. source.nushell
  • }
  • all - keyword.other.builtin.nushell
    • ...
      1. keyword.control.nushell
      2. meta.command.nushell
      3. meta.function.body.nushell
      4. source.nushell
    • $rest
      1. variable.other.nushell
      2. meta.command.nushell
      3. meta.function.body.nushell
      4. source.nushell
• cmd - entity.name.type.external.nushell
  • ...
    1. keyword.control.nushell
    2. meta.command.nushell
    3. source.nushell
  • $rest
    1. variable.other.nushell
    2. meta.command.nushell
    3. source.nushell
• ^ - keyword.operator.nushell
  • cmd ...$rest - same as above

[fdncred]

The only thing that I'm not quite sure about is having ...$rest as a custom command parameter instead of ...rest. They resolve to two different things.

...rest is all variable.parameter.nushell
where
...$rest is ... = keyword.control.nushell, $ = meta.function.parameter.nushell, and rest = variable.parameter.nushell

It may be ok like this, it just gives me pause.

[texastoland]

...rest is all variable.parameter.nushell

@fdncred Fixed. Copied from Discord whether to highlight flags too:

def cmd [ --flag ] {}
#         ^^ highlighted?
cmd --flag
#   ^^ here too

[fdncred]

My answer from Disord was I think yes to both since -- and flag mean something different than --flag. Thanks for working on this stuff.

[texastoland]

Ready again. I wasn't happy with my first pass but I discovered an expression that wasn't working before and fixed it. I didn't update the scope list (above) with flag tokens but can if it helps review! LGTM

[fdncred]

I think it looks good now. Thanks!