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priority_queue.py
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priority_queue.py
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"""Implements a priority queue for LPA*"""
import heapq
class Queue():
"""Binomial heap augmented with hashtable.
Note: This can be copy.deepcopy'd correctly."""
def __init__(self):
self._U = []
self._set = set([])
def insert(self, item):
heapq.heappush(self._U, item)
self._set.add(item)
def top(self):
if len(self._U) > 0:
return self._U[0]
else:
return None
def topKey(self):
t = self.top()
if type(t) == tuple:
return t
else:
if t is None:
return (float("inf"), float("inf"))
else:
return t.k
def pop(self):
item = heapq.heappop(self._U)
self._set.remove(item)
return item
def remove(self, item):
self._set.remove(item)
self._U.remove(item)
heapq.heapify(self._U)
def __contains__(self, key):
return key in self._set
def __len__(self):
return len(self._U)
def printQueue(self):
for u in self._U:
print u
def __str__(self):
toReturn = "note: this destroys the queue\n\n"
while len(self._U) > 0:
u = self.pop()
toReturn += "%s\n" % (str(u),)
return toReturn