(feature request) Heredoc Slim support (or a way to add custom heredoc syntaxes)

[rafasoares]

Environment

• vscode-ruby version: 0.16.0
• Ruby version: 2.5.0
• VS Code version: 1.20.1
• Operating System: macOS High Sierra 10.13.3

Expected behavior

Color Slim heredocs syntax the same way it works with HTML

Actual behavior

Slim heredocs are colored as strings

Steps to reproduce the problem

Additional Notes

Perhaps the best approach would be to allow a setting for custom heredoc matching. Something like:

"ruby.heredoc.customSyntaxes": {
  "SLIM": "slim",
  "MATCHER": "vscode-syntax-key"
}

[wingrunr21]

Hmm, I will look into this.

This also raises a larger question as to whether we should be directly supporting HAML or Slim or leaving that to other extensions.

[rafasoares]

That's why I suggested the customization options. Simply set a matcher and the syntax key. The highlighting itself would be handled by VS Code or the appropriate extension.

I'm pretty sure this is how it works already (looking at

vscode-ruby/syntaxes/ruby.cson.json

Line 1558 in 72ae6af

"comment": "Heredoc with embedded html",

), but with a fixed list of syntaxes, thus adding another one for Slim would be a lot easier. Unless I missed something and you include syntax rules for things like SQL, GraphQL, CSS and XML in the vscode-ruby extension, of course.

[wingrunr21]

Except the syntax is loaded at extension load time and I've not yet found a way to modify the syntax via runtime configuration options

[rafasoares]

I see. Is there no way to reload the extension upon changes in ruby.* settings?

PS: This is why I thought just adding a "Heredoc with embedded Slim" syntax would be easier.

[wingrunr21]

Reloading the extension wouldn't do anything. VSCode loads the grammar based on the stuff in package.json and uses that for syntax highlighting.

I also don't want to be doing one-off edits to the grammar just to support specific uses cases. For instance, there's nothing that requires you to use <<-SLIM as the heredoc delimiter. How would we support slim detection via <<-TEMPLATE? Allowing VSCode to properly detect embedded languages and apply the appropriate syntax is a better option here (similar to what we do with ERB here). The problem with this approach is that it's basically going to require an entry for every language you can embed in a Heredoc.