controller.rb

def sass_literals(file_path)
  engine = Sass::Engine.for_file(file_path, {})
  environment = Sass::Environment.new
  
  keyvals = []
  
  engine.to_tree.children.each do |node|
    next unless node.kind_of? Sass::Tree::VariableNode
    if node.expr.kind_of? Sass::Script::Tree::Literal
      value = node.expr.perform(environment)
      keyvals.push [node.name, value.to_s]
    end
  end
  
  return keyvals
end