rton_cli.rb

#!/usr/bin/env ruby

require "rton"
include Automaton

pda = Automaton.setup(:pda) do
  initial_state :q0 do
    transition ['a', EMPTY], [:q0, 'A']
    transition ['b', 'A'],   [:q1, EMPTY]
  end

  state :q1 do
    transition ['b', 'A'],   [:q1, EMPTY]
  end

  final_states :q0, :q1
end

loop do
  print "Input: "
  input = gets
  break if input.nil?
  input = input.chomp.strip.split("") # simple tokenization

  if pda.recognize?(input)
    puts "The input was recognized by the automaton"
  else
    puts "The input was rejected by the automaton"
  end
end

# $ ruby rton_cli.rb 
# Input: aabb
# The input was recognized by the automaton
# Input: aaaabbbb
# The input was recognized by the automaton
# Input: abb
# The input was rejected by the automaton