toy robot on a table created by mike1011 - https://repl.it/Iafm/11

toy robot on a table.rb

##DIRECTION
class A
  def initialize(sym, dx, dy, left, right)
    @name, @dx, @dy, @left, @right = sym.to_s, dx, dy, left, right
  end

  def to_s
    @name
  end

  def left
    A.const_get(@left)
  end

  def right
    A.const_get(@right)
  end

  def advance(x, y)
    [x + @dx, y + @dy]
  end

  @all = [
    [:EAST,  +1,  0],
    [:NORTH,  0, +1],
    [:WEST,  -1,  0],
    [:SOUTH,  0, -1],
  ]
  @all.each_with_index do |(sym, dx, dy), i|
    self.const_set(sym,
                   A.new(sym, dx, dy, @all[(i + 1) % @all.size].first,
                                              @all[(i - 1) % @all.size].first))
  end
  class << self
    def [](name)
      A.const_get(name) if A.const_defined?(name)
    end
  end  

end

class Invalid < Exception ; end
  
# Mixin for toy
##COMMANDS
module B
  def place(x, y, face)
    validate(x = (x.to_i if /\A\d+\Z/.match(x)),
             y = (y.to_i if /\A\d+\Z/.match(y)),
             face = A[face.upcase])
    @x, @y, @face = x, y, face
  end

  def move
    raise Invalid.new unless @face
    new_x, new_y = @face.advance(@x, @y)
    validate(new_x, new_y, @face)
    @x, @y = new_x, new_y
  end

  def left
    raise Invalid.new unless @face
    @face = @face.left
  end

  def right
    raise Invalid.new unless @face
    @face = @face.right
  end

  def report
    raise Invalid.new unless @face
    puts "Current position===> POSITION X:#{@x}, POSITION Y:#{@y}, FACING:#{@face} ======"
  end
end

##FOR TOY ROBOT
class C
  include B

  def initialize(board_size=5, output=STDOUT)
    @board_size = board_size
    @output = output
  end

  def execute(cmd)
    cmd = cmd.strip.downcase
    op, args = cmd.split(/\s+/, 2)
    args = args.split(/\s*,\s*/) if args
    raise Invalid.new unless B.public_method_defined?(op)
    begin
      send(op, *args)
    rescue ArgumentError
      raise Invalid.new
    end
  end

  def execute_script(io)
    io.each_line do |line|
      begin
        execute(line)
      rescue Invalid
        #puts "(Ignored invalid)"
      end
    end
  end

  private
  def validate(x, y, f)
    raise Invalid.new unless x && y && f
    raise Invalid.new unless (0..@board_size) === x
    raise Invalid.new unless (0..@board_size) === y
  end
end

C.new.execute_script(ARGF)

TRY THE ABOVE CODE HERE - https://repl.it/Iafm/16

EXAMPLE -

REPORT
Current position===> POSITION X:0, POSITION Y:0, FACING:NORTH ======
PLACE 0,4,EAST
MOVE
LEFT
MOVE
REPORT
Current position===> POSITION X:1, POSITION Y:5, FACING:NORTH ======