Source code for bidict._frozenordered

# Copyright 2009-2022 Joshua Bronson. All Rights Reserved.
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#← Prev: _orderedbase.py  Current: _frozenordered.py  Next: _orderedbidict.py →
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"""Provide :class:`FrozenOrderedBidict`, an immutable, hashable, ordered bidict."""

import typing as _t

from ._frozenbidict import frozenbidict
from ._orderedbase import OrderedBidictBase
from ._typing import KT, VT, KeysView


class FrozenOrderedBidict(OrderedBidictBase[KT, VT]):
    """Hashable, immutable, ordered bidict type.

    Like a hashable :class:`bidict.OrderedBidict`
    without the mutating APIs, or like a
    reversible :class:`bidict.frozenbidict` even on Python < 3.8.
    (All bidicts are order-preserving when never mutated, so frozenbidict is
    already order-preserving, but only on Python 3.8+, where dicts are
    reversible, are all bidicts (including frozenbidict) also reversible.)

    If you are using Python 3.8+, frozenbidict gives you everything that
    FrozenOrderedBidict gives you, but with less space overhead.
    """

    __hash__ = frozenbidict.__hash__

    if _t.TYPE_CHECKING:
        @property
        def inverse(self) -> 'FrozenOrderedBidict[VT, KT]': ...

    # Delegate to backing dicts for more efficient implementations of keys() and values().
    # Possible with FrozenOrderedBidict but not OrderedBidict since FrozenOrderedBidict
    # is immutable, i.e. these can't get out of sync after initialization due to mutation.
[docs] def keys(self) -> KeysView[KT]: """A set-like object providing a view on the contained keys. See :meth:`bidict.BidictBase.keys` for more info. """ return self._fwdm._fwdm.keys() # type: ignore[return-value]
[docs] def values(self) -> KeysView[VT]: """A set-like object providing a view on the contained values. See :meth:`bidict.BidictBase.values` for more info. """ return self._invm._fwdm.keys() # type: ignore[return-value]
# Can't delegate for items() because values in _fwdm and _invm are nodes. # On Python 3.8+, delegate to backing dicts for a more efficient implementation # of __iter__ and __reversed__ (both of which call this _iter() method): if hasattr(dict, '__reversed__'): def _iter(self, *, reverse: bool = False) -> _t.Iterator[KT]: itfn = reversed if reverse else iter return itfn(self._fwdm._fwdm) # type: ignore [operator,no-any-return] else: # On Python < 3.8, just optimize __iter__:
[docs] def _iter(self, *, reverse: bool = False) -> _t.Iterator[KT]: if not reverse: return iter(self._fwdm._fwdm) return super()._iter(reverse=True)
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