Re: Tree sitter question / problem

[Theodor Thornhill <theo@thornhill.no>]

Hi there, Perry

Perry Smith <pedz@easesoftware.com> writes:

> As a result of not knowing what I’m doing, this took me a half a day to figure this out.  And I fear it is going to be hard for me to explain things.  Feel free to ask me questions.
>
> I’m working on ruby-ts-mode and it is patterned mostly after c-ts-mode because I want the versatility.
>
> I have this bit of code and it is the content of the comment that is the topic of the email:
>
> ;; doc/keywords.rdoc in the Ruby git repository considers these to be
> ;; reserved keywords.  If these keywords are added to the list, it
> ;; causes the font-lock to stop working.
> ;;
> ;; "__ENCODING__" "__FILE__" "__LINE__" "false" "self" "super" "true"
> ;;
> ;; "nil" (which does not exhibit this issue) is also considered a
> ;; keyword but I removed it and added it as a constant.
> ;;
> (defun ruby-ts-mode--keywords (language)
>   "Ruby keywords for tree-sitter font-locking.
> Currently LANGUAGE is ignored but shoule be set to `ruby'."
>   (let ((common-keywords
>          '("BEGIN" "END" "alias" "and" "begin" "break" "case" "class"
>            "def" "defined?" "do" "else" "elsif" "end" "ensure" "for"
>            "if" "in" "module" "next" "not" "or" "redo" "rescue"
>            "retry" "return" "then" "undef" "unless" "until" "when"
>            "while" "yield")))
>     common-keywords))
>

If you try (treesit-query-validate 'ruby (ruby-ts-mode--keywords 'ruby))
you should get a validation error and some help.  My guess is that
'false' and 'true' are nodes in their own right, such as (true) (false).

...

Yeah, you need to use the nodes separately [0].

> I also have this in my ruby-ts-mode--font-lock-settings:
>
>    :language language
>    :feature 'keyword
>    `([,@(ruby-ts-mode--keywords language)] @font-lock-keyword-face)
>
> (I understand this is just two snippets of a more complex set up but I’m hoping that c-ts-mode can be reviewed for more context if needed.)
>
> The Ruby parser I got from git@github.com:casouri/tree-sitter-module.git and followed the instructions.
>
> As the comment states, if I add “false” into the list of keywords,
> then **none** of the keywords get highlighted.  I can understand that
> “false” doesn’t get highlighted for some reason but having the entire
> query stop working seems like it might be a bug or at least a weakness
> that should be addressed.

That may be, but this is for major mode authors, so it is likely we can
live with these difficulties, IMO.

>
> If I turn on treesit-inspect-mode and put the cursor on top of false
> in a Ruby file, it says only (false) instead of something like (while
> “while”) that other keyword nodes that do not exhibit this problem
> show and I’m jumping to the conclusion that that is part of the
> problem.

This is because it is a node, and not a keyword.


[0]: https://github.com/tree-sitter/tree-sitter-ruby/blob/master/grammar.js#L533-L541