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queue.py
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executable file
·67 lines (48 loc) · 1.42 KB
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#!/usr/bin/env python
# -*- coding:utf-8 -*-
__author__ = 'MFC'
__time__ = '2020/6/19 22:55'
"""
9.队列
https://www.bilibili.com/video/BV1ZE411P7ov?p=9
FIFO 先进先出
利用之前写的单链表来实现
用工具实现变更后自动执行单元测试
when-changed -r -v -1 -s ./ 'pytest -s queue.py'
"""
from .linked_list import LinkedList # 利用之前写的linked_list
# 用Linked List实现Queue （用链表实现队列）
class FullError(Exception):
pass
class EmptyError(Exception):
pass
class Queue:
def __init__(self, maxsize=None):
self.maxsize = maxsize
self._item_linked_list = LinkedList()
def __len__(self):
return len(self._item_linked_list)
def push(self, value):
if self.maxsize is not None and len(self) >= self.maxsize:
raise FullError('queue full')
return self._item_linked_list.append(value)
def pop(self):
if len(self) <= 0:
raise EmptyError('queue empty')
return self._item_linked_list.popleft()
# 编写测试代码
def test_queue():
q = Queue()
q.push(0)
q.push(1)
q.push(2)
assert len(q) == 3
assert q.pop() == 0
assert q.pop() == 1
assert q.pop() == 2
assert len(q) == 0
import pytest
with pytest.raises(EmptyError) as excinfo:
q.pop() # raise EmptyError
assert 'queue empty' == str(excinfo.value)
assert 'empty' in str(excinfo.value)