# C/C++ 로 배우는 자료구조론 연습문제 7.24

class CircularQueue

  def initialize(size)
    @memory = []
    @front = 0
    @rear = 0

    @queue_size = size
  end

  def is_empty
    return @front == @rear
  end

  def is_full
    return ((@rear + 1) % @queue_size) == @front
  end

  def enqueue(data)
    return nil if is_full

    @rear = (@rear + 1) % @queue_size
    @memory[@rear] = data
  end

  def dequeue
    return nil if is_empty
    
    @front = (@front + 1) % @queue_size
    return @memory[@front]
  end
end

class Stack

  def initialize(size)
    @top = -1

    @memory = []
    @stack_size = size
  end

  def is_full
    return @top >= (@stack_size - 1)
  end

  def is_empty
    return @top == -1
  end

  def push(data)
    return nil if is_full

    @top += 1

    @memory[@top] = data
  end

  def pop
    return nil if is_empty

    data = @memory[@top]

    @top -= 1

    return data
  end

end

def stack_to_queue(stack)
  temp_stack = Stack.new 5
  
  until stack.is_empty
    temp_stack.push stack.pop
  end
  
  queue = CircularQueue.new 6
  
  until temp_stack.is_empty
    queue.enqueue temp_stack.pop
  end
  
  return queue
end

stack = Stack.new 5
stack.push "A"
stack.push "B"
stack.push "C"
stack.push "D"
stack.push "E"
queue = stack_to_queue stack
until queue.is_empty
  puts queue.dequeue
end

puts stack.is_empty

A
B
C
D
E
true