Source code for bidict._frozenbidict

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# Copyright 2009-2021 Joshua Bronson. All Rights Reserved.
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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__ = ()

    # 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]': ...

[docs] 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 return self._hash # type: ignore
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