I'm trying to implement css modules for haml. I've added a processor for the attributes to archive that: https://github.com/sebastiandeutsch/haml/blob/feature/process_attributes_and_values/lib/haml/compiler.rb#L417. See implementation of the processor below. Now I have the problem that I need to set the context for the processor within a file on…

actual.html

<div class="test__container___1qISr">
  Hello World!
  <div class="test__container___1qISr">
    Test
  </div>
</div>

css_classes.json

{
  "stylesheets/application.css": {
    "container": [
      "application__container___1q3ub"
    ]
  },
  "stylesheets/index.css": {
    "container": [
      "index__container___Az6C0"
    ]
  },
  "stylesheets/test.css": {
    "container": [
      "test__container___1qISr"
    ]
  }
}

css_modules_processor.rb

class CssModulesProcessor
  def call(attr, value, options)
    puts "********** CssModulesProcessor ************** called"
    puts options.inspect
    puts options[:css_module_context]
    puts options.filename
    puts "********** /CssModulesProcessor ************* called"

    file = File.read(File.join(Rails.root, 'webpack', 'dist', 'css_classes.json'))
    css_modules = JSON.parse(file)

    if attr == 'class'
      if css_modules[options[:css_module_context]].present?
        value = css_modules[options[:css_module_context]][value] if css_modules[options[:css_module_context]].key?(value)
      end
    end

    return attr, value
  end
end

Haml::Template.options[:attr_processor] = CssModulesProcessor.new
Haml::Template.options[:css_module_context] = "stylesheets/application.css"

expected.html

<div class="index__container___Az6C0">
  Hello World!
  <div class="test__container___1qISr">
    Test
  </div>
</div>

index.html.haml

- Haml::Template.options[:css_module_context] = "stylesheets/index.css"
.container
  Hello World!
  - Haml::Template.options[:css_module_context] = "stylesheets/test.css"
  .container
    Test