feat(syntax)!: reimplement the syntax highlighter

[Jint-lzxy]

Initially proposed in ayamir/nvimdots#676 (comment). The goal of this PR is also described there :)

This PR updated copious highlight groups and added support for LSP Semantic Tokens. The following is a list of modified hl groups with reasons for such modifications. The hl groups marked as NS indicate I'm still on the fence about whether these changes should be implemented:

• LNK(group): Links to group
• NEW(col): [For undefined highlight groups] New color col
• IFP(parent, child): Inherited from the parent class. child, classified under parent, should have a similar color to the parent class.
• R(before, after): Replace before with after
• [+/-] B/I/U: Bold, Italics, Underline
• FNC: Follow Naming Convention
• NS: Not Sure

NS	hl group	operation	reason
	Search	bg: R(darkened sky, surface1) fg: R(text, pink) style: +B	Selected a color similar to CurSearch to avoid confusion (things could get worse when using many highlights with different responsibilities). Added B for differentiation.
	IncSearch	bg: R(darkened sky, pink) fg: R(mantle, surface1)	Invert of Search
	Identifier	fg: R(flamingo, text)	Following @variable. It is widely used, so should have a trivial color.
	@variable	LNK(Identifier)	FNC: Any variable name
	Label	fg: R(sapphire, rosewater)	IFP(Statement, Label) (The reason for not using the same color as the parent class is b/c they still have subtle semantic differences)
●	Keyword	fg: R(mauve, red?)	Classified as any other keyword, so it should have a different color than the parent class. I haven't figured out whether to use red or maroon yet. (Should avoid having the same color as @variable.builtin)
	Exception	fg: NEW(peach)	Inherited from @exception
	Include	fg: R(mauve, teal)	To have a similar color to Included (which links to String).
●	Macro	LNK(Constant?)	Although both vim/nvim link it to Define by default, macros are still constants, aren't they?
●	StorageClass	LNK(Keyword?)	Although it is classified under Type, AFAIK many syntax highlighters tend to label that as Keyword (also by definition): C++ Standard - §5.11 [lex.key]
●	Structure	LNK(Keyword?)	ditto. Structure itself is not a valid type.
	Delimiter	fg: NEW(teal)	The definition for hl-group Delimiter has changed: "delimiters (e.g. ; / . / ,)". Therefore, a suitable color was chosen for it.
●	@function.macro	LNK(Constant?)	I tend to link it to Constant for the same reason as Macro. But I'm not sure if it looks good in every language.
	@parameter	fg: R(maroon, rosewater)	rosewater is more suitable for the elements under this classification.
	@keyword.operator	LNK(Operator)	FNC: new keyword operator
	@keyword.return	fg: R(maroon, pink)	N/A
	@variable.builtin	style: +styles.properties	Add styles.properties to indicate builtin types (same hereinafter)
●	@constant.builtin	fg: R(peach, lavender?)	Sometimes builtin constants are not just constants literally, so it was given another color for differentiation. For example, in C++ nullptr is a prvalue of type std::nullptr_t.
	@parameter	fg: R(maroon, pink)	Replaced by a softer color.
●	@type.qualifier	LNK(Constant?)	FNC: Type qualifiers should be keywords.
	@field @property	fg: R(lavender, rosewater)	Same as Identifier. Assigned a trivial color.
●	Diagnostics···Hint	fg: R(teal, rosewater)	IMO "Hints" shouldn't be that eye-catching. It almost matches the color of DiagnosticsInfo.

[sgoudham]

Hiya there 👋
Thanks for submitting the PR and putting a lot of thought into it!

We actually merged in our code editor style guide a while ago to try and normalise the colours within all Catppuccin editors. While we can't expect every editor to follow the guideline set, we aim for it to be detailed enough for editors to implement well.

I would encourage you to submit a PR against the main repository against that table as there are definitely improvements that can be made (e.g. we were having discussions on our discord about trying to standardise the search highlights) instead of just neovim as it will be more transparent for everyone to comment on before merging in improvements to all the editors

Hope that's okay! @Jint-lzxy

[rewhile]

@class @struct @enum @enumMember @event @interface @modifier @regexp @typeParameter @decorator

Yes, these highlights were removed in favor of lsp rule-based semantic in neovim/neovim@1cc23e1

[Jint-lzxy]

Hi @sgoudham Sorry for the delay! I did notice the style guide last year, but at that time it was still a WIP. Glad to hear that it has been updated recently 👍

I would encourage you to submit a PR against the main repository against that table as there are definitely improvements that can be made.

OK no probs - I will sort out a list of possible highlight categories based on :h group-name, :h treesitter-highlight-groups, and Language Server Protocol Specification and open a PR against the main repository that applies to generic code editors (including reasons for such changes like this PR), where we can continue our discussion 😃

[ayamir]

Any progress for it?

[Jint-lzxy]

Any progress for it?

Sorry for my discontinued availability. I've created a PR at catppuccin/catppuccin#2109 😃

[rewhile]

I don't think @keyword.operator should be linked to Operator

Before

After

[Jint-lzxy]

I don't think @keyword.operator should be linked to Operator

My original motivation was to "differentiate @keyword.operator (i.e. operators that are English words) from other elements" - which mainly emphasizes the operator part:

Before
After

Otherwise, these nodes may have colors similar to many other elements (under the newly proposed style guide): like "Tags", "Reserved Constants", "Specials", etc. Thus implicitly(?) indicating that they have similar "intrinsics". (My intention was to prevent unrelated nodes from having similar colors)

But indeed this is not a perfect solution, especially when considering function-style operators: The relatively bright color C.sky can make a single element stand out, thus would be useful on isolated nodes, but when the element comes with a pre- (or suf-)fix of different color(s), this time the overly bright color can make the node look peculiar. Maybe we can make a special rule for this?

[Jint-lzxy]

I'm going to close this PR and open a new one that follows the updated standard captures (working on this right now lmao), bc nvim-treesitter/nvim-treesitter#5895 (and #630) have already been merged, and I kinda messed up the commit history 🙈