"""Python implementation of a priorityq."""

from src.binheap import Binheap

class PriorityQ(object):

"""

Priority Q data structure.

Following methods are supported.

Insert(value, [priority]): inserts a value into the queue.

Takes an optional argument for that value's priority.

pop(): removes the most important item from the queue

and returns its value.

peek(): returns the most important item without removing it from the queue.

"""

def __init__(self):

"""Initialize priorityq."""

self._container = Binheap()

def insert(self, val, priority=0):

"""Insert a val into the queue with an argument for the priority."""

self._container.push((priority, val))

def pop(self):

"""Remove the most important item from the queue."""

to_return = self._container.container[1][1]

if not to_return:

raise(IndexError, 'Can\'t pop from an empty queue.')

self._container.pop()

return to_return

def peek(self):

"""Return the most important item without removing it."""

try:

return self._container.container[1][1]

except IndexError:

return None