Python uses list to implement a non-marginal priority queue (based on class, including iterator)

Python uses list to implement a non-marginal priority queue (based on class, including iterator)

#!/usr/bin/python # -*- coding: utf-8 -*-'''Created on 2015-2-4@author: beyondzhou@name: test_listpriorityqueue.py'''def test_listpriorityqueue():        # import pyListQueue    from myqueue import ListPriorityQueue        print '#Init a queue named smith using enqueue'    smith = ListPriorityQueue()    smith.enqueue('purple', 5)    smith.enqueue('black', 1)    smith.enqueue('orange', 3)    smith.enqueue('white', 0)    smith.enqueue('green', 1)    smith.enqueue('yellow', 5)            print '#output smith queue'    for element in smith:        print element               print '#dequeue one item'    smith.dequeue()        print '#output smith after dequeue'    for element in smith:        print element             print '#dequeue another item'    smith.dequeue()        print '#output smith after dequeue another item'    for element in smith:        print element             print '#get the length of queue'    print 'the lenght of queue is ', len(smith)        print '#check wheter the queue is empty'    if smith.isEmpty():        print 'stack is empty!'    else:        print 'stack is not empty!'            print '#dequeue all items'    while not smith.isEmpty():        smith.dequeue()        print '#check wheter the queue is empty after dequeue all items'    if smith.isEmpty():        print 'stack is empty!'    else:        print 'stack is not empty!'    if __name__ == __main__:    test_listpriorityqueue()

# Implementation of the unbounded Priority Queue ADT using a Python list# with new items appended to the endclass ListPriorityQueue:    # Create an empty unbounded priority queue    def __init__(self):        self._qList = list()    # Returns True if the queue is empty    def isEmpty(self):        return len(self) == 0    # Returns the number of items in the queue    def __len__(self):        return len(self._qList)    # Adds the given item to the queue    def enqueue(self, item, priority):        # Create a new instance of the storage class and append it to the list        entry = _ListPriorityQEntry(item, priority)        self._qList.append(entry)    # Removes and returns the first item in the queue    def dequeue(self):        assert not self.isEmpty(), Cannot dequeue from an empty queue.                # Find the entry with the highest priority        highest = self._qList[0].priority        index = 0        for i in range(self.__len__()):            # See if the ith entry contains a higher priority (smaller integer).            if self._qList[i].priority < highest:                highest = self._qList[i].priority                index = i                        # Remove the entry with the highest priority and return the item        entry = self._qList.pop(index)                    return entry.item    # Returns the array queue's iterator for traversing the elements    def __iter__(self):        return _ListPriorityQueueIterator(self._qList)# Private storage class for associating queue items with their priorityclass _ListPriorityQEntry(object):    def __init__(self, item, priority):        self.item = item        self.priority = priority# Implementation of iterclass _ListPriorityQueueIterator:    def __init__(self, theList):        self._setItems = theList        self._curItem = 0    def __iter__(self):        return self    def next(self):        if self._curItem < len(self._setItems):            item = self._setItems[self._curItem]            self._curItem += 1            return item.item, item.priority        else:            raise StopIteration

#Init a queue named smith using enqueue#output smith queue('purple', 5)('black', 1)('orange', 3)('white', 0)('green', 1)('yellow', 5)#dequeue one item#output smith after dequeue('purple', 5)('black', 1)('orange', 3)('green', 1)('yellow', 5)www.bkjia.com#dequeue another item#output smith after dequeue another item('purple', 5)('orange', 3)('green', 1)('yellow', 5)#get the length of queuethe lenght of queue is  4#check wheter the queue is emptystack is not empty!#dequeue all items#check wheter the queue is empty after dequeue all itemsstack is empty!