Help with Fontification

Help with Fontification

[Reza Nikoopour]

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Hello All,

I'm working on refactoring terraform mode and I've stumbled across
a fontification issue I cannot figure out how to solve.

[image: image.png]

A resource can be broken down into the three parts:
The keyword "resource", the resource type (green in the image), and the
resource
name (pink in the image).

The resource name and type are string literals so I
used the override flag for the regex when setting font-lock-defaults:
(defvar terraform-font-lock-keywords
  ;; other code
  (,terraform--block-builtins-with-type-and-name--type-highlight-regexp 2
'terraform--resource-type t)
  (,terraform--block-builtins-with-type-and-name--name-highlight-regexp 3
'terraform--resource-name t)))

(define-derived-mode terraform-mode prog-mode "Terraform"
  ;; other code
  (setq font-lock-defaults '((terraform-font-lock-keywords))))

However, this is causing the issue above where the search based
highlighting is
overriding the comment highlighting.

Is there a way to only have search based fontification only override
strings but
keep comments unaltered?

Cheers,
Reza

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Re: Help with Fontification

[Stefan Monnier]

> The resource name and type are string literals so I
> used the override flag for the regex when setting font-lock-defaults:
> (defvar terraform-font-lock-keywords
>   ;; other code
>   (,terraform--block-builtins-with-type-and-name--type-highlight-regexp
>    2 'terraform--resource-type t)
>   (,terraform--block-builtins-with-type-and-name--name-highlight-regexp
>    3 'terraform--resource-name t)))
[...]
> Is there a way to only have search based fontification only override
> strings but keep comments unaltered?

Yes: the "face" part of the specs above are actually arbitrary ELisp
expressions, so you can do things like:

    (defvar terraform-font-lock-keywords
      ;; other code
      (,terraform--block-builtins-with-type-and-name--type-highlight-regexp
       2 (unless (nth 4 (syntax-ppss)) 'terraform--resource-type) t)
      (,terraform--block-builtins-with-type-and-name--name-highlight-regexp
       3 (unless (nth 4 (syntax-ppss)) 'terraform--resource-name) t)))

Another option is to replace the regexps by functions (which internally
can use the same regexps, of course) and have those functions check (nth
4 (syntax-ppss)) to see if the match is inside a comment (and skip to
the next match if so),


        Stefan