63 lines
1.5 KiB
Python
63 lines
1.5 KiB
Python
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import collections
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import threading
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import typing
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from collections.abc import Iterable, Iterator, MutableMapping
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from .func import locked
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__all__ = ['LRU']
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K = typing.TypeVar('K')
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V = typing.TypeVar('V')
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class LRU(MutableMapping[K, V], typing.Generic[K, V]):
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"""
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Implementation of a length-limited O(1) LRU map.
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Original Copyright 2003 Josiah Carlson, later rebuilt on OrderedDict and added typing.
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"""
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def __init__(self, count: int, pairs: Iterable[tuple[K, V]] = ()):
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self._lock = threading.RLock()
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self.count = max(count, 1)
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self.d: collections.OrderedDict[K, V] = collections.OrderedDict()
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for key, value in pairs:
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self[key] = value
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@locked
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def __contains__(self, obj: K) -> bool:
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return obj in self.d
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@locked
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def __getitem__(self, obj: K) -> V:
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a = self.d[obj]
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self.d.move_to_end(obj, last=False)
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return a
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@locked
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def __setitem__(self, obj: K, val: V):
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self.d[obj] = val
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self.d.move_to_end(obj, last=False)
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while len(self.d) > self.count:
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self.d.popitem(last=True)
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@locked
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def __delitem__(self, obj: K):
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del self.d[obj]
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@locked
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def __len__(self) -> int:
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return len(self.d)
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@locked
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def __iter__(self) -> Iterator[K]:
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return iter(self.d)
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@locked
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def pop(self, key: K) -> V:
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return self.d.pop(key)
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@locked
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def clear(self):
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self.d.clear()
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