bazarr/libs/bidict/_frozenbidict.py

61 lines
2.5 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2009-2021 Joshua Bronson. All Rights Reserved.
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#==============================================================================
# * Welcome to the bidict source code *
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"""Provide :class:`frozenbidict`, an immutable, hashable bidirectional mapping type."""
import typing as _t
from ._delegating import _DelegatingBidict
from ._typing import KT, VT
class frozenbidict(_DelegatingBidict[KT, VT]):
"""Immutable, hashable bidict type."""
__slots__ = ('_hash',)
_hash: int
# Work around lack of support for higher-kinded types in mypy.
# Ref: https://github.com/python/typing/issues/548#issuecomment-621571821
# Remove this and similar type stubs from other classes if support is ever added.
if _t.TYPE_CHECKING:
@property
def inverse(self) -> 'frozenbidict[VT, KT]': ...
def __hash__(self) -> int:
"""The hash of this bidict as determined by its items."""
if getattr(self, '_hash', None) is None:
self._hash = _t.ItemsView(self)._hash() # type: ignore [attr-defined]
return self._hash
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