Source code for bidict._orderedbidict

# Copyright 2009-2022 Joshua Bronson. All Rights Reserved.
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"""Provide :class:`OrderedBidict`."""

import typing as _t

from ._mut import MutableBidict
from ._orderedbase import OrderedBidictBase
from ._typing import KT, VT


class OrderedBidict(OrderedBidictBase[KT, VT], MutableBidict[KT, VT]):
    """Mutable bidict type that maintains items in insertion order."""

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

[docs] def clear(self) -> None: """Remove all items.""" self._fwdm.clear() self._invm.clear() self._sntl.nxt = self._sntl.prv = self._sntl
[docs] def popitem(self, last: bool = True) -> _t.Tuple[KT, VT]: """*x.popitem() → (k, v)* Remove and return the most recently added item as a (key, value) pair if *last* is True, else the least recently added item. :raises KeyError: if *x* is empty. """ if not self: raise KeyError('mapping is empty') itfn: _t.Callable = reversed if last else iter # type: ignore [assignment] it = itfn(self) key = next(it) val = self._pop(key) return key, val
[docs] def move_to_end(self, key: KT, last: bool = True) -> None: """Move an existing key to the beginning or end of this ordered bidict. The item is moved to the end if *last* is True, else to the beginning. :raises KeyError: if the key does not exist """ node = self._fwdm[key] node.prv.nxt = node.nxt node.nxt.prv = node.prv sntl = self._sntl if last: lastnode = sntl.prv node.prv = lastnode node.nxt = sntl sntl.prv = lastnode.nxt = node else: firstnode = sntl.nxt node.prv = sntl node.nxt = firstnode sntl.nxt = firstnode.prv = node
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