ripper_event_viewer.rb

require 'ripper'

class RipperEventViewer < Ripper::SexpBuilderPP
  (Ripper::PARSER_EVENTS + Ripper::SCANNER_EVENTS).each do |ev|
    eval <<~RUBY
      def on_#{ev}(*args)
        super.tap do
          puts "#{'*'*50} on_#{ev}"
          pp(*args)
        end
      end
    RUBY
  end
end

RipperEventViewer.parse ARGF.read