source: geniuswebcore/geniusweb/PriorityQueue.py@ 100

Last change on this file since 100 was 100, checked in by ruud, 19 months ago

python installs also wheel to avoid error messages

File size: 1.9 KB
Line 
1from heapq import heappush, heappop
2from queue import Queue
3from typing import TypeVar, Generic, Callable, List, Set
4
5
6T=TypeVar("T")
7class Wrap(Generic[T]):
8 '''
9 Wrapper that has __lt__.
10 We wrap objects that possibly don't implement __lt__
11 in the queue in this to avoid
12 heapq crashing on a call to __lt__
13 '''
14 def __init__(self, obj:T, lessthanfunction):
15 '''
16 @param obj the object to be wrapped.
17 @param lessthanfunction a function that
18 when called with another object,
19 returns true iff other object is < this.
20 '''
21 self._obj=obj
22 self._lessthanfunction = lessthanfunction
23 def get(self) -> T:
24 return self._obj
25 def __repr__(self):
26 return str(self._obj)
27 def __lt__(self, other):
28 return self._lessthanfunction(self.get(), other.get())
29
30class PriorityQueue(Queue, Generic[T]):
31 '''Variant of Queue that retrieves open entries in priority order (lowest first).
32 This differs from queue.PriorityQueue as it allows custom comparator function.
33 Another difference is that entries are
34 '''
35
36 def __init__(self, lessthanfunction:Callable[[T,T], bool]):
37 '''
38 @param lessthanfunction a function with arguments (this, other)
39 that is used to sort the queue.
40 If queue should have the "smallest" item at head,
41 this function should return true iff other object is < this.
42 '''
43 super().__init__()
44 self._queue:List[Wrap[T]] = []
45 self._lessthanfunction=lessthanfunction
46
47 def _qsize(self)->int:
48 return len(self._queue)
49
50 def _put(self, item:T):
51 heappush(self._queue, Wrap(item, self._lessthanfunction))
52
53 def _get(self)->T:
54 return heappop(self._queue).get()
55
56 def __repr__(self)->str:
57 return str(self._queue)
58
59 def __iter__(self):
60 return iter([w.get() for w in self._queue])
61
62
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