Ripper for syntax

ripper_again_yalls.rb

require 'ripper'

Ripper::SexpBuilder.instance_methods.grep(/error/i) # => [:on_alias_error, :on_assign_error, :on_class_name_error, :on_param_error, :on_parse_error]

class DemoBuilder < Ripper::SexpBuilder
  instance_methods.each do |meth_name|
    next unless meth_name =~ /^on_/
    super_meth = instance_method meth_name
    define_method meth_name do |*args|
      super_meth.bind(self).call(*args).tap do |result|
        puts "#{meth_name}(#{args.map(&:inspect).join(', ')})".ljust(50) << " #> #{result.inspect}"
      end
    end
  end
end

src = %(+)
DemoBuilder.new(src).parse
# >> on_op("+")                                         #> [:@op, "+", [1, 0]]
# >> on_parse_error("syntax error, unexpected $end")    #> [:parse_error, "syntax error, unexpected $end"]