My first state machine! Hooray!

strip

STATE_CHOPPING_FRONT = 0
#STATE_ITERATING_END = 1
STATE_CHOPPING_END = 2
STATE_FINISHED = 3

def strip(array)
  state = STATE_CHOPPING_FRONT
  loop do
    if state == STATE_CHOPPING_FRONT then
      if array[0].white_space?
        array.delete_at(0) # array.shift
      else
        state = STATE_CHOPPING_END
      end
    elsif state == STATE_CHOPPING_END then
      if array.last.white_space?
        array.delete_at(array.length - 1) # array.pop
      else
        state = STATE_FINISHED
      end
    elsif state == STATE_FINISHED
      break
    end
  end
  array
end

class String
  def white_space?
    self == " " || self == "\t" || self == "\r" || self == "\n"
  end
end

p strip(" foo   ".split(''))
p strip(" foo   b".split(''))
p strip("b foo   ".split(''))
p strip("foo".split(''))
p strip("f oo".split(''))
p strip("\tfoo   \n".split(''))