Fix case class/object highlighting

[Hydrotoast]

Hi maintainers,

Problem. The case keyword is assigned the scope keyword.control.flow.scala in the declarations case class and case object. This seems incorrect. See the image below.

Proposal. After investigating, I discovered that the corresponding pattern did not account for whitespace between the case keyword and the class/object keywords. To fix this, we propose two changes in this PR:

• matched potential whitespace between case and class/object declarations and
• extracted an independent pattern for the trait declarations because they cannot be preceded by a case keyword.

The image below shows the result after these changes have been applied.

[olafurpg]

Thank you for this contribution @Hydrotoast ! I agree that the current syntax highlighting for case class and case object is not good, and your screenshot looks much better 👍 Nice job tracking down the necessary changes in the syntax definition!

LGTM 👍 wdyt @nicolasstucki ?

[nicolasstucki]

What happens with match/case? Does this also affect that colouring.

[nicolasstucki]

Also how do other class modifiers look? Such as private, protected, ...

[Hydrotoast]

Thanks for looking at the PR, @olafurpg and @nicolasstucki !

@nicolasstucki As requested, I have attached a screenshot with

• several variations of class/object-level modifiers and
• a match-case control flow expression nested within a case class.

Note 1. In the screenshots, the color theme is "Dark +", which is provided by default. Generally, I think the colors may be misleading. For example, if we had a color scheme that assigned both scopes keyword.control.flow.scala and keyword.declaration.scala to the same color, then this issue may have been overlooked!

From the original code, it seemed clear that the case in case class was intended to be assigned the scope keyword.declaration.scala rather than keyword.control.flow.scala.

Note 2 (Out of scope). I am familiar with developing VS Code plugins or TextMate grammars: is there a generally accepted way to test changes to the TextMate grammars? I think automated tests may help prevent potentially undesirable syntax highlighting.

[nicolasstucki]

Thank @Hydrotoast