ArrayQueue.py

import numpy as np
from Interfaces import Queue


class ArrayQueue(Queue):
    def __init__(self):
        self.n = 0
        self.j = 0
        self.a = self.new_array(1)

    def new_array(self, n: int) -> np.array:
        return np.zeros(n, object)

    def resize(self):
        '''
            Resize the array
        '''
        b = self.new_array(max(1, 2*self.n))
        for k in range(self.n):
            b[k] = self.a[(self.j + k) % len(self.a)]
        self.a = b
        self.j = 0

    def add(self, x: object):
        '''
            shift all j > i one position to the right
            and add element x in position i
        '''
        if len(self.a) == self.n:
            self.resize()
        self.a[(self.j + self.n) % len(self.a)] = x
        self.n += 1
        return True

    def remove(self) -> object:
        '''
            remove the first element in the queue
        '''

        if self.n <= 0:
            raise IndexError
        x = self.a[self.j]
        self.a[self.j] = 0
        self.j = (self.j + 1) % len(self.a)
        self.n -= 1
        if len(self.a) > 3*self.n:
            self.resize()
        return x

    def size(self):
        return self.n

    def __str__(self):
        s = "["
        for i in range(0, self.n):
            s += "%r" % self.a[(i + self.j) % len(self.a)]
            if i < self.n - 1:
                s += ","
        return s + "]"

    def __iter__(self):
        self.iterator = 0
        return self

    def __next__(self):
        if self.iterator < self.n:
            x = self.a[self.iterator]
            self.iterator += 1
        else:
            raise StopIteration()
        return x