Queue 的简单实现

queue.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# This is a Queue implementing in list.


class Queue():
    def __init__(self):
        self._content = list()

    def __len__(self):
        return len(self._content)

    def _is_empty(self):
        return len(self) == 0

    def __str__(self):
        return str(self._content)

    def enqueue(self, element):
        self._content.append(element)

    def dequeue(self):
        assert not self._is_empty()
        self._content = self._content[1:]


# The following shows how to use class Queue
if __name__ == "__main__":
    queue_demo = Queue()
    for i in range(5):
        queue_demo.enqueue(i ** 4)
    print "Original queue is:", queue_demo

    print "Enter your choice:\n\
            1: enqueue a element;\n\
            2: dequeue a element:\n\
            3: print the queue;\n\
            EOF: exit the program."

    choice = "3"
    while(choice != EOFError):
        try:
            choice = raw_input("->")
            if choice == "1":
                queue_demo.enqueue(raw_input("Enter the element: "))
                print "After enqueue: ", queue_demo
            elif choice == "2":
                queue_demo.dequeue()
                print "After dequeue: ", queue_demo
            elif choice == "3":
                print queue_demo
            else:
                print "Wrong input!"
                continue

        except EOFError:
            print "Exit......"
            break