#!/usr/bin/env python
# -*- coding: UTF-8 -*-
__author__ = 'Julio Tentor <jtentor@fi.unju.edu.ar>'


import numpy


class Queue(object):
    def __init__(self, capacity = 10):
        self.__capacity = capacity
        self.__data = numpy.empty(self.__capacity, numpy.object)
        self.__head = 0
        self.__tail = 0
        self.__count = 0


    def __len__(self):
        return self.__count


    def __next__(self, pos):
        pos += 1
        return 0 if (pos >= self.__capacity) else pos


    def append(self, x):
        if self.__count >= self.__capacity:
            raise ValueError("ERROR La cola está llena...")
        self.__data[self.__tail] = x
        self.__tail = self.__next__(self.__tail)
        self.__count += 1


    def popleft(self):
        if self.__count <= 0:
            raise ValueError("ERROR La cola está vacía...")
        result = self.__data[self.__head]
        self.__head = self.__next__(self.__head)
        self.__count -= 1
        return result


if __name__ == "__main__":
    pass