gistfile1

cursor = 0

a     = (1..5).to_a
b     = []
stack = []

while true
  if cursor < a.size
    b << a[cursor]
    stack << cursor
    cursor += 1

    p b
  else
    if stack.empty?
      break
    end
    b.pop
    cursor = stack.pop
    cursor += 1
  end
end