A PriorityQueue or MinHeap implementation. Items with the smallest cost are popped first. Object orientated interface for `heapq` (Python standard library).

priority_queue.py

import heapq

class PriorityQueue:
    """
    A PriorityQueue or MinHeap implementation.
    Items with the smallest cost are popped first.
    """

    def __init__(self):
        self.h = []
        self.idx = -1

    def push(self, cost, item):
        self.idx += 1
        heapq.heappush(self.h, (cost, self.idx, item))

    def pop(self):
        cost, _, item = heapq.heappop(self.h)
        return cost, item

    def peek(self):
        return self[0]

    def __getitem__(self, i):
        cost, _, item = self.h[i]
        return cost, item

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