PrismScanner: Contextual parsing for Rails

[davidwessman]

• Adding a scanner based on Prism.
• It supports
  • before_action in controllers
  • translations in nested method calls
  • model_name.human
  • human_attribute_name

Note to reviewers

The scanner could replace all our calls to the parser gem today and could in the future also replace our matchers.
The harder part is to make it extendable, should we allow the end user to implement their own Prism::Visitor that would support some new use case?

I left the email subjects and ViewComponent for a smaller future PR, but I think this is a nice base to start testing it out on some real apps and evaluate if this is something we want to move towards.

---

TODO

• Handle comments
• Add magic comment to skip parsing file
• Handle all arguments to translation method
• Handle Rails-model calls
• Handle more before_actions, or warn that they cannot be processed

Future features

• Handle email subjects
• Handle ViewComponent translations
• Handle default argument

[glebm]

We already have a Ruby parser dependency, consider reusing it rather than adding another one.

[davidwessman]

We already have a Ruby parser dependency, consider reusing it rather than adding another one.

Prism is a standard ruby gem and is included by default from Ruby 3.3 and can be installed from Ruby 3.0.
I think we should investigate moving away from parser towards it.

I will do this experiment in Prism and then I can rewrite it to use the old parser.

When parsing controllers I would like to return a key or a fallback, e.g. if there is a relative key in a method name I would like the key with either the method name included or with just the controller namespace.

class EventsController < ApplicationController
  def show
    t(".relative")
  end
end

Then I would like it to first check for events.show.relative, but if that does not exist, fallback to events.relative.
Do you have any idea where to start with adding such behaviour?

[glebm]

I don't mind dropping support for older rubies, but does Prism support JRuby?
If so, switching to Prism throughout might be a good idea

Then I would like it to first check for events.show.relative, but if that does not exist, fallback to events.relative.

Absolute keys are resolved by calling absolute_key:

i18n-tasks/lib/i18n/tasks/scanners/relative_keys.rb

Lines 7 to 12 in 2a9a9e0

	# @param key [String] relative i18n key (starts with a .)
	# @param path [String] path to the file containing the key
	# @param roots [Array<String>] paths to relative roots
	# @param calling_method [#call, Symbol, String, false, nil]
	# @return [String] absolute version of the key
	def absolute_key(key, path, roots: config[:relative_roots],

Sounds like the code calling absolute_key would need to have access to the data:

i18n-tasks/lib/i18n/tasks/data.rb

Lines 11 to 13 in 2a9a9e0

	# I18n data provider
	# @see I18n::Tasks::Data::FileSystem
	def data

[glebm]

Looks like Prism on JRuby is still a work-in-progress: http://blog.jruby.org/2024/02/jruby-prism-parser

[jaredmoody]

+1 for Prism! The speed gains rubocop is getting from using it are 👀

[davidwessman]

Looks like Prism on JRuby is still a work-in-progress: http://blog.jruby.org/2024/02/jruby-prism-parser

I think this means that JRuby are working on replacing their parser with Prism, for their compilation.
Prism can still handle all syntax that JRuby supports and can run in JRuby, so for our use-case it would be okay.

[davidwessman]

Maybe we would like some different way to return a pluralized translation, e.g. that it would just return activerecord.models.event with some pluralized setting and then this can be included in the tree.

[glebm]

Yeah, I think that would be necessary to support pluralized keys properly.
Can be done in a follow-up PR

[davidwessman]

@glebm Now I feel like I am ready for a review of this as a beta-feature.

I am sorry for a large PR, please let me know if you have any suggestions for making it smaller and more reviewable.