Remove default syntax highlighting

[mikelu92]

Hi,

I'm trying to figure out how to remove highlighting for variables. For context, In the go language, I just want to have the variable declarations highlighted. Anytime a variable is used though I want it to not be highlighted. In the current highlighting code it highlights all variables (identifiers). Is there a way to remove the highlighting on identifiers?

I've figured out how to isolate just declarations as follows:

(tree-sitter-hl-add-patterns 'go                                         
  [(short_var_declaration left: (expression_list (identifier) @variable))
   (var_declaration (var_spec name: (identifier) @variable))])

but I don't know what capture name (if any) to use for just the (identifier) highlighting. Any tips?

[ubolonton]

We don't have a mechanism to selectively remove a specific highlighting pattern yet.

There are 2 things you can do at the moment:

1. Copy the query pattern file returned by (tree-sitter-langs--hl-query-path 'go). Modify it to suit your need. Then advise the function tree-sitter-langs--hl-query-path to return that file instead. For example:

(define-advice tree-sitter-langs--hl-query-path (:before-until (lang-symbol) override-default-patterns)
  (pcase lang-symbol
    ('go "/path/to/your/modified/highlights.scm")))

Not highlighting all identifiers as @variable is actually consistent with tree-sitter-langs's styles. The Go patterns should be modified to do so. A pull request is welcome.

2. Add new patterns that override the default patterns. For example:

;; tree-sitter-hl.el doesn't have this face, but it probably should.
(defface tree-sitter-hl-face:nil
  '((default :inherit default))
  ""
  :group 'tree-sitter-hl-faces)

(tree-sitter-hl-add-patterns 'go
  [(short_var_declaration left: (expression_list (identifier) @variable))
   (var_declaration (var_spec name: (identifier) @variable))
   ;; This is prioritized over the default from highlights.scm.
   (identifier) @nil])

[mikelu92]

hey @ubolonton I think some time after you posted this something was update that your define-advice snippet no longer works. Whever I open up a go file I get the following error:

tree-sitter-after-on-hook: (wrong-number-of-arguments ((t) (lang-symbol) (if (eq lang-symbol 'go) (let nil "/my/modified/highlights/go-highlights.scm"))) 2)

Could you advise on why this is happening now? Sorry I'm not that versed in elisp

[mikelu92]

nvm figured it out, just needed to change it to the following:

(define-advice tree-sitter-langs--hl-query-path (:before-until (lang-symbol &optional mode) override-default-patterns)
  (pcase lang-symbol
    ('go "/path/to/your/modified/highlights.scm")))

because that function was changed in the following commit

[mikelu92]

@ubolonton thanks for the response! Is there something that documents tree-sitter-langs styles? In case I want to make a pr for go to match it completely

[ubolonton]

There is no documentation on that yet. The rule of thumb is following the docstrings of the faces defined in tree-sitter-hl.el.

Some notable conventions are:

• Definitions and uses should be differentiated. Examples:
  • @function vs. @function.call.
  • @method vs. @method.call.
  • @type.parameter vs. @type.argument.
  • @variable vs. none: variable uses should not be highlighted.
• Special faces should have high priority (placed earlier in the pattern list): @function.macro, @type.builtin, @variable.special.
• "Contextual" patterns should have low priority (placed at the end). Example: string interpolation.

Note that the package tree-sitter-langs provides its own highlighting patterns. This page lists languages whose highlighting patterns have been substantially modified compared to upstreams'. You can use them as examples.