"""
 priorityqueue.py

 >>> from priorityqueue import PriorityQueue
 
 >>> pq = PriorityQueue()
 >>> pq.push(15)
 >>> pq.push(10)
 >>> pq.push(12)
 >>> pq.pop()
 10
 >>> pq.pop()
 12
 >>> pq.pop()
 15
 
 >>> pq2 = PriorityQueue([2, 15, 7, 4])
 >>> [x+1 for x in pq2]
 [3, 5, 8, 16]
 >>> len(pq2)
 4
 >>> str(pq2)
 '[2, 4, 7, 15]'
 >>> pq2[0]
 2
 >>> pq2[0] = 9

 An object wrapper around Python's heapq package
 (see http://docs.python.org/library/heapq.html).
 I just didn't like their API.

 Jim M | MIT License | Feb 21 2012
"""

from heapq import heapify, heappush, heappop
from doctest import testmod

class PriorityQueue(object):
    def __init__(self, queue=[]):
        self.heap = queue
        heapify(self.heap)
    def push(self, item):
        heappush(self.heap, item)
    def pop(self):
        return heappop(self.heap)
    def __str__(self):
        return str(self.heap)
    def __len__(self):
        return len(self.heap)
    def __getitem__(self, key):
        return self.heap[key]
    def __setitem__(self, key, value):
        self.heap[key] = value
    def __iter__(self):
        self.popped = []
        heapify(self.popped)
        return self
    def next(self):
        if len(self)==0:
            self.heap = self.popped
            self.popped = None
            raise StopIteration
        else:
            x = self.pop()
            heappush(self.popped, x)
            return x

if __name__ == "__main__":
    testmod()