require 'ripper'
module Req
  module_function
  def libs(code)
    Ripper.lex(code).
      map {|pos, event, value| [event, value] }.
      select {|event, value| event == :on_const or event == :on_op && value == '::' }.
      map {|event, value| value }.
      unshift(nil).
      each_cons(2).inject([]) {|memo, (before, e)| before == '::' || e == '::' ?  memo : memo << e } -
      Object.constants.map(&:to_s)
  end

  def format(libs)
    libs.map {|l| "require '#{l.downcase}'" }.join "\n"
  end
end

code = <<EOF
Nokogiri::HTML('<b>hello Twitter</b>')
p Time.now
EOF

include Req
puts format libs code